<%BANNER%>

Strength, Modulus of Elasticity, Shrinkage and Creep of Concrete

Permanent Link: http://ufdc.ufl.edu/UFE0021579/00001

Material Information

Title: Strength, Modulus of Elasticity, Shrinkage and Creep of Concrete
Physical Description: 1 online resource (217 p.)
Language: english
Creator: Liu, Yanjun
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2007

Subjects

Subjects / Keywords: aggregate, creep, gauge, modulus, prediction, regression, shrinkage, strength
Civil and Coastal Engineering -- Dissertations, Academic -- UF
Genre: Civil Engineering thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: In the application of prestressed concrete, there are concerns on severe prestress loss caused mainly by elastic shortening, shrinkage and creep of concrete, which will result in the extreme reduction of the design capacity of prestressed concrete structure, or even the premature structure failure. Hence, the values of elastic modulus, ultimate shrinkage strain, and ultimate creep coefficient of concrete have to be estimated reasonably and accurately at the production stage in order to avoid loss of structural capacity, or even unexpected structural failure caused by prestress loss. At present, the modulus of elasticity, shrinkage and creep properties of concrete that are used in structural design are either based on the arbitrary available literature or based on the limited research of the locally available materials. Thus, there is a great need for a comprehensive testing and evaluation of locally available concrete mixes to determine their mechanical and physical properties so that correct values for these properties can be used in structural design. Also, there is a great need to design a simple, effective, practical and reliable creep apparatus to carry this massive investigation on creep behavior of concrete out. In this study, a creep test apparatus was designed, and twenty four creep apparatus were constructed for use in performing creep tests. The creep apparatus was evaluated to be working satisfactorily. An effective creep testing procedure was developed and documented. Also, a gauge point position guide was designed for installing gauge point on the cylindrical mold and it was proved to be an effective tool in preparation of specimens for creep tests. In addition, an alignment frame was designed and it was proved to be a very useful tool to ensure that the specimens can be set up in the creep apparatus vertically. In this study, 14 concrete mixtures were evaluated, and replicate batches for ten of these mixes were also produced and evaluated. Three types of coarse aggregate, fly ash and ground blast-furnace slag were incorporated in the mix designs in this study. Concrete specimens were fabricated and tested for their compressive strength, splitting tensile strength, elastic modulus, shrinkage and creep. This study has generated valuable data and determined general trends on the compressive strength, splitting tensile strength, elastic modulus, drying shrinkage strains and creep coefficient of structural concretes investigated in this study. Most importantly, the inter-relationships among compressive strength, elastic modulus and shrinkage and creep properties of concrete were found through regression analysis. These relationships make the predictions of shrinkage and creep possible with the information from compressive strength and elastic modulus.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Yanjun Liu.
Thesis: Thesis (Ph.D.)--University of Florida, 2007.
Local: Adviser: Tia, Mang.
Local: Co-adviser: Roque, Reynaldo.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2007
System ID: UFE0021579:00001

Permanent Link: http://ufdc.ufl.edu/UFE0021579/00001

Material Information

Title: Strength, Modulus of Elasticity, Shrinkage and Creep of Concrete
Physical Description: 1 online resource (217 p.)
Language: english
Creator: Liu, Yanjun
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2007

Subjects

Subjects / Keywords: aggregate, creep, gauge, modulus, prediction, regression, shrinkage, strength
Civil and Coastal Engineering -- Dissertations, Academic -- UF
Genre: Civil Engineering thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: In the application of prestressed concrete, there are concerns on severe prestress loss caused mainly by elastic shortening, shrinkage and creep of concrete, which will result in the extreme reduction of the design capacity of prestressed concrete structure, or even the premature structure failure. Hence, the values of elastic modulus, ultimate shrinkage strain, and ultimate creep coefficient of concrete have to be estimated reasonably and accurately at the production stage in order to avoid loss of structural capacity, or even unexpected structural failure caused by prestress loss. At present, the modulus of elasticity, shrinkage and creep properties of concrete that are used in structural design are either based on the arbitrary available literature or based on the limited research of the locally available materials. Thus, there is a great need for a comprehensive testing and evaluation of locally available concrete mixes to determine their mechanical and physical properties so that correct values for these properties can be used in structural design. Also, there is a great need to design a simple, effective, practical and reliable creep apparatus to carry this massive investigation on creep behavior of concrete out. In this study, a creep test apparatus was designed, and twenty four creep apparatus were constructed for use in performing creep tests. The creep apparatus was evaluated to be working satisfactorily. An effective creep testing procedure was developed and documented. Also, a gauge point position guide was designed for installing gauge point on the cylindrical mold and it was proved to be an effective tool in preparation of specimens for creep tests. In addition, an alignment frame was designed and it was proved to be a very useful tool to ensure that the specimens can be set up in the creep apparatus vertically. In this study, 14 concrete mixtures were evaluated, and replicate batches for ten of these mixes were also produced and evaluated. Three types of coarse aggregate, fly ash and ground blast-furnace slag were incorporated in the mix designs in this study. Concrete specimens were fabricated and tested for their compressive strength, splitting tensile strength, elastic modulus, shrinkage and creep. This study has generated valuable data and determined general trends on the compressive strength, splitting tensile strength, elastic modulus, drying shrinkage strains and creep coefficient of structural concretes investigated in this study. Most importantly, the inter-relationships among compressive strength, elastic modulus and shrinkage and creep properties of concrete were found through regression analysis. These relationships make the predictions of shrinkage and creep possible with the information from compressive strength and elastic modulus.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Yanjun Liu.
Thesis: Thesis (Ph.D.)--University of Florida, 2007.
Local: Adviser: Tia, Mang.
Local: Co-adviser: Roque, Reynaldo.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2007
System ID: UFE0021579:00001


This item has the following downloads:


Full Text
xml version 1.0 encoding UTF-8
REPORT xmlns http:www.fcla.edudlsmddaitss xmlns:xsi http:www.w3.org2001XMLSchema-instance xsi:schemaLocation http:www.fcla.edudlsmddaitssdaitssReport.xsd
INGEST IEID E20101118_AAAAAI INGEST_TIME 2010-11-18T07:29:31Z PACKAGE UFE0021579_00001
AGREEMENT_INFO ACCOUNT UF PROJECT UFDC
FILES
FILE SIZE 52616 DFID F20101118_AAAFRI ORIGIN DEPOSITOR PATH liu_y_Page_166.pro GLOBAL false PRESERVATION BIT MESSAGE_DIGEST ALGORITHM MD5
ab30f5bf9b47ff23b27c365b5552c64c
SHA-1
cac1db99bddc91f6b1f6f0ec11f94089e4f031c4
35175 F20101118_AAAFQU liu_y_Page_152.pro
9a74bea365d3623ee19e14c51ba5bdfe
82131a836111619eb1f3ce104212197173755da9
102304 F20101118_AAAEOG liu_y_Page_059.jpg
dbfbbfad6aa152063389f396b7e5a35b
ae60ad5d9a7febd78f4a2c4a43ba59ea7fee9631
73686 F20101118_AAAENS liu_y_Page_045.jpg
650a89a1599a10ed321a918e0b856068
aaa1f96a6f482020a13e81cf0b0253e9d5cf9db2
11384 F20101118_AAAFRJ liu_y_Page_167.pro
aa5d31936517ff2cd0bf4adc2ea6d001
27fc68f7fecef89c85dd6792fa9b18dbc256e3d9
33730 F20101118_AAAFQV liu_y_Page_153.pro
00a30516a6694df8c740fb26cdf52547
d4c680bb379e6d8dd0a2b9baf29832664156507d
38245 F20101118_AAAEOH liu_y_Page_060.jpg
617807406ff8002120b04c68beef5328
1c7878db7a3b79f6fbde11b94df7ac81cf4efff1
69356 F20101118_AAAENT liu_y_Page_046.jpg
83cc3b06ba8584b46c4bcdb721034a3a
072bd5153374845e8a9dcfea72dd216617e76708
30778 F20101118_AAAFRK liu_y_Page_168.pro
6a199a0216f3a908693ce46b5b0c3a8b
514902cd172af29ba1f7a2243fe0a9cea2827409
48250 F20101118_AAAEOI liu_y_Page_061.jpg
e8e88d4b686d00b00514da8844da6966
f0a0293154762d653e181e35866b739abfeb6f3c
35183 F20101118_AAAFRL liu_y_Page_169.pro
7b37299c68708d06c2718c3a6d0e5efc
d8f93ba4c6ad22cf4fc021a8bb04050ee71e3607
19982 F20101118_AAAFQW liu_y_Page_154.pro
eed28a8b24d3df88a1c99a6baf21a2b6
38c890ecc42bfbf1c7c7f0b009c64670ba9c63f2
31152 F20101118_AAAEOJ liu_y_Page_062.jpg
38699b0681ad0e5471e2be5893aca57b
4e5a946dea41f7e1cf6f8427081aa73878195084
64225 F20101118_AAAENU liu_y_Page_047.jpg
c7d6f9f3294b2b056cc5f014d5eb3e46
4480dbed8dbec9134478112681a4f4491495e8cd
37145 F20101118_AAAFSA liu_y_Page_184.pro
766ac7d9b1215cf769bedef753e92b0f
e143287fa0671f150aa12fa59d7049b9f1a32813
32840 F20101118_AAAFRM liu_y_Page_170.pro
6726c27f0511e388ce55e888e981aecd
06e78e2399d6f9ad453ccdb2d614740434e60d37
40509 F20101118_AAAFQX liu_y_Page_155.pro
3a07780536a5ec0ba224c0b23bbcb9c5
3ada94926894d169af463b1be3df1a8ed1108d14
31682 F20101118_AAAEOK liu_y_Page_063.jpg
8f9723bcc249b4953b24f878d7a7af4d
d921c0137709262812acf98cb980bb59eaac03aa
83015 F20101118_AAAENV liu_y_Page_048.jpg
80b40d64963793f016733c37af7d12d8
e9b37b98c5761d07959f17084ca1529208623e3e
59789 F20101118_AAAFSB liu_y_Page_185.pro
99bd3f0219fa5e23b479951e105b0ca6
32c1d0b7ec00e3991177b72cac10cce2709022c3
32774 F20101118_AAAFRN liu_y_Page_171.pro
cfb6beb6ba919db493c51f82c25735f9
5a9e493d3685c4a7d4f8448008afebf8fd832339
51748 F20101118_AAAFQY liu_y_Page_156.pro
b5c8b2edc4ec473d6c52af805fd7996e
f4bcda0f78a0a11273ee79723cd64176f0520406
64781 F20101118_AAAEOL liu_y_Page_064.jpg
1c75940e766ca08a66c1a2129e63ff3f
660adcc4154da928fa6438ab93d2b83f7cd9c8bd
78108 F20101118_AAAENW liu_y_Page_049.jpg
b37eac7e525dd0870bd14f01a41a8d13
69390b07751fe34999b4d074abbbcfae7ab00e9a
18670 F20101118_AAAFSC liu_y_Page_186.pro
51ba8e0587acfd0a16d78ac1209a5fae
7de4eb7ffc3706ea1178e115823b0cc43cdf6f36
34927 F20101118_AAAFRO liu_y_Page_172.pro
867f150543dd7bc7d5820e16e28e7aee
7faf74dfb9ab41cc3510d8c23a03b93bc5065451
29551 F20101118_AAAFQZ liu_y_Page_157.pro
b422892135b5cf4afc58febc5ab3440a
dc4fa893941fc2eef8d24f6359e58b39833fd5c9
64564 F20101118_AAAEPA liu_y_Page_079.jpg
91ec9e7dc7443f71b8bb2659329e7c75
d795299155f8cd5209b9a042e5cc553015c3c652
78222 F20101118_AAAEOM liu_y_Page_065.jpg
90fb96215beff87f686ed92e0170caa6
a8e74852099106629cdd11053bfa9b9de725731f
83834 F20101118_AAAENX liu_y_Page_050.jpg
1a4cbd1cd4d96e557fe6e16a50ef2078
f24e3e704be91487a93b886ca3239c4feef3df14
51236 F20101118_AAAFSD liu_y_Page_187.pro
4436ca18af5c997ee005fa553254b879
a99a91c8e507a6fd817fe2dcb689a0e015a20dac
42980 F20101118_AAAFRP liu_y_Page_173.pro
c38d28ff837afda31010f2a9cadd5845
a3e220f18be0868074f87a3affd3cf04a35ad97c
65948 F20101118_AAAEPB liu_y_Page_080.jpg
fb0a4931f7f4596e66953a91efdbfed2
a092ac5624d4d3a90822913bc0f2987b53d87dcf
81596 F20101118_AAAEON liu_y_Page_066.jpg
c34b727eebb45903a7ce4f513a425003
123aaa0f4e3c1d06ac5fc4d43ba1addd894d07a6
85826 F20101118_AAAENY liu_y_Page_051.jpg
45b198252f8c6609ba17cbf7b1727117
28501befe07377e503f0e8c0ab80cbe8fb6593a4
42243 F20101118_AAAFSE liu_y_Page_188.pro
249ed319763d0b882c3d62be50df4588
f48effb9021da24fb5401fa3afee0c19d9c5b61c
61623 F20101118_AAAFRQ liu_y_Page_174.pro
c0652165c2f7a9ce2f1c00c3f77234d2
b2e7fcc725b51291b8cc2325a5afc85f0d1241c4
78197 F20101118_AAAEPC liu_y_Page_081.jpg
e09cc158480b1ee27aee8623deb62580
ea77d904bb62803db0fd075c5fb09f849ccb6e63
84233 F20101118_AAAEOO liu_y_Page_067.jpg
a6ef8aeb8680e4444b385fc6bf2bc153
487a5d108561aa7f1af41ff44b7cbc2dabc09b00
49696 F20101118_AAAENZ liu_y_Page_052.jpg
420d6b27c5d09e21fc515686a3146cce
338a1e02c7409c72241122b1e6fb733dd534f38a
63845 F20101118_AAAFSF liu_y_Page_189.pro
c43f0be6b210a5dd4176710f414706d3
60ada8f97ccd0f44c9f985ca30aa4613107c055b
25993 F20101118_AAAFRR liu_y_Page_175.pro
fa6b4dcb0142e171e8e7632a79d39782
02cd40588bdf199a11cc3c8647e13afb4c4e8054
26971 F20101118_AAAEPD liu_y_Page_082.jpg
0c484a676095933f206c2c8405d379bf
9c5082a183cee01ed5b24b34ebcd7f14aac53c59
73116 F20101118_AAAEOP liu_y_Page_068.jpg
620c8fb8936950aeae44fce0a7b71c63
89f9dc9726de57a8310c2cdf004f56a0edb742d2
60749 F20101118_AAAFSG liu_y_Page_190.pro
e46cc94f50202b4229db57143102dce2
537cb5bc97b155fc4beabfa5e1b5c8594dfef37e
29738 F20101118_AAAFRS liu_y_Page_176.pro
39d5936bfed6f4ae9d1539cae351c3db
bba9fe84a5bcae8e9e13d7c771b3fca5d18a147f
60947 F20101118_AAAEOQ liu_y_Page_069.jpg
729b15af7c283a75de48c7d7721c853f
4fdc5311508f20b8d9e3ec033fa3b90a219e537d
36542 F20101118_AAAEPE liu_y_Page_083.jpg
e4ca18d56a51d9c028d0d037e06b848d
a9629d22f4082a898d5b476a956bdd6ced1ff044
43861 F20101118_AAAFSH liu_y_Page_191.pro
c231c028de3d073e9dba582335c82de3
1584cfc6941abecad0a703e2fa0e4c3ccdf82c96
34810 F20101118_AAAFRT liu_y_Page_177.pro
c85879e1830a2591ceca919b2e4d0c1e
39ec3f16cb00fe8f0edf8ef849e2cdd32bf07fa7
56643 F20101118_AAAEOR liu_y_Page_070.jpg
78ca66a4e6ff15b068f1572199666653
2327a7414fb05abd7eec00ef3946fc0a76b61064
90050 F20101118_AAAEPF liu_y_Page_084.jpg
c8d2922c5de7fc4950ecd5fc63b337cc
dfde7550b741db122c291e4c6735e1227bf79e4d
1417 F20101118_AAAFSI liu_y_Page_192.pro
0f4e538fabf58730a128ee47ad0b6fad
05438c571056822f8b5748e637d323185f8989f9
36441 F20101118_AAAFRU liu_y_Page_178.pro
05f4ce09127ebadf2867f3f6cb2a04ba
1519aed834e0fe9cc384fb492643f82d564d58e2
77735 F20101118_AAAEOS liu_y_Page_071.jpg
8fb96ec1cd200d7d444883970c359527
7756d66da01209c163673c28efdab6a7e370b6c0
92244 F20101118_AAAEPG liu_y_Page_085.jpg
02defff1d4f152249226f4531002d9f1
480f93d0ceff113259e1b8775aa6150bae32b177
34271 F20101118_AAAFSJ liu_y_Page_193.pro
14f10d65412c3992122815685de5c9f1
5c45b9afc9488ea6597bb984ac357e40830c169a
31948 F20101118_AAAFRV liu_y_Page_179.pro
faf4163f98101e9b9a9dfce259b117cc
8b48458bbc2e60e4066a326443b0ad367bc43ab9
64559 F20101118_AAAEOT liu_y_Page_072.jpg
4930f828c1edd5b6c93a497d4d252538
039aa9bd100e8a3b448876cb6801b58d7de8c6fd
51341 F20101118_AAAEPH liu_y_Page_086.jpg
c65eef3d54933c816b80cdaab1bf6a5e
4d5f9041dff0bad5b6935cb63a3eacaad595cdb1
32163 F20101118_AAAFSK liu_y_Page_194.pro
28f4e67abb3c9159f8a22242bd203c84
cde45c5177be9480da4b6c30326273feef0fdaa8
30958 F20101118_AAAFRW liu_y_Page_180.pro
5c9465e5fcc1d55eb5e3111581b7d73b
bc3652b55de78225e66f8935df46cbbb9b4b42d2
58244 F20101118_AAAEOU liu_y_Page_073.jpg
064542e5ee7463f760b2e52ff78f4cab
bc5e500268cb9fb591c1b6883f9b594298a80424
48343 F20101118_AAAEPI liu_y_Page_087.jpg
920442cc17c1e04a7389d7c82e80e887
b5eebf13ac6a648c78b36e62340100bf6d91fad8
39342 F20101118_AAAFSL liu_y_Page_195.pro
482485ee5af4d6213ae52ea34f069c07
8857faa79ac8d8dae6437160ba1482120ccb9ef7
77120 F20101118_AAAEPJ liu_y_Page_088.jpg
126e4e11e7ec13f9f5bd318ee72b214b
42aa32e3adf9290d4c510961fb747a3f8f30e68f
45242 F20101118_AAAFTA liu_y_Page_210.pro
c37aaabb99c7c6998b07d784771e97d2
d6c56ec446da2425c30c7160a5795ff37446657e
33478 F20101118_AAAFSM liu_y_Page_196.pro
ab2efb9d06e02493ed8d7e76ed4bcd9c
ce45d153d05c53ba3c4d91cc8f383bedce757085
23435 F20101118_AAAFRX liu_y_Page_181.pro
73b42c8dacb14aee48ac053ea995b5d6
c1098d5ce73daea2d6412436bac4555b10891696
12002 F20101118_AAAEOV liu_y_Page_074.jpg
5e3238453518d38ca7a01c2bf27df272
51f57769752ba0b549e7a6a77c2c372571ca30dd
89185 F20101118_AAAEPK liu_y_Page_089.jpg
00eea2a5bd5a85247328a226a7bc11ab
049a671208bc8d78230cc82310945c80e538d97d
63649 F20101118_AAAFTB liu_y_Page_211.pro
c8e1fdf61b64de8fc2049a688a774ac4
86e03580c38bf23d4386d4d7b5731219449f1141
39347 F20101118_AAAFSN liu_y_Page_197.pro
0acdcd6171476ad3a7e71d6c6857e230
a96fddfaf4d7d95ba90d2169abfbdff7101ccbc0
29273 F20101118_AAAFRY liu_y_Page_182.pro
4c69b1c2704faa5b199301ec143e9763
53771aca515413e3c7e7b450f5391ad6e8a051df
81058 F20101118_AAAEOW liu_y_Page_075.jpg
59173a3360c201a8288fd86f192ac214
ad77060d234a1b76630fcbfc2127fe10171aa6b3
54752 F20101118_AAAEPL liu_y_Page_090.jpg
cafb3b7b6820787ff297397d942fb194
a0e1a5a17c7e8fad786d6214d8884229102f42ae
62897 F20101118_AAAFTC liu_y_Page_212.pro
1aec2b90df4745772a14caa8cc99977a
fcd05ea94e0496b88c0e866c233fd07f8b826754
1833 F20101118_AAAFSO liu_y_Page_198.pro
cc107e858059401999fd99d9d2d94659
b9fdca0faa704b49f14fce43a79f15f0d914922d
29910 F20101118_AAAFRZ liu_y_Page_183.pro
18d6fdf2dd8af346528f76f6b93376e6
de7254cd24ac2f78c902ce3fe689222b9e6f95a2
58782 F20101118_AAAEOX liu_y_Page_076.jpg
0d58028cc509beb883cbcb6610ce53b2
c201c44e4d4c7403b8acfbf17359eceadde0e9f0
36273 F20101118_AAAEQA liu_y_Page_105.jpg
adac0bab068dd3dae46af12a8f2dae6d
cadb47dba0d54defc8062d36c3989bbf93e5dcf5
62373 F20101118_AAAEPM liu_y_Page_091.jpg
a181407f5ed4cab6b2e57cb7a66f6f9a
05f35d930770c59bae03f0a1cf58e58bd826c414
68402 F20101118_AAAFTD liu_y_Page_213.pro
74938190baba828a672aa389337ed608
74cee358c9d39b88fa11963a1453758d7887d86f
48061 F20101118_AAAFSP liu_y_Page_199.pro
fd47b65905b0d43bcd3d6816759ac5b0
4597482387581514fae125b8e33c7942766a87e1
61373 F20101118_AAAEOY liu_y_Page_077.jpg
ba62e9f70baf29cdcc9a4002ecdbbce9
3afbfaa535a37d06bdf1d021e81b139f071012db
56014 F20101118_AAAEQB liu_y_Page_106.jpg
a62f96796dba65c601ef2b73b18f3875
ee3c11a86ec9875fac0c5d64beb2a1c90257d06f
59772 F20101118_AAAEPN liu_y_Page_092.jpg
713214175d01df1c2d325e2243c3c927
65016f8f9213e5703a3b2575b9c34395a840babe
61536 F20101118_AAAFTE liu_y_Page_214.pro
192249f72199c74bec445d4326f33aa5
9ecb569b173518ba48efca7c7b0ec6d28c1f8b6d
43876 F20101118_AAAFSQ liu_y_Page_200.pro
ae3b1502ca540b1a3530566221e17982
efa979c0d4c98eabb0e3e19bdb1386537dc80a15
68772 F20101118_AAAEOZ liu_y_Page_078.jpg
f80c4bb50b553d0e3e59e5f0d73b586b
aa49989e2a18acbd43fa28bc86c37ddf3b5d3cf8
30140 F20101118_AAAEQC liu_y_Page_107.jpg
4614f45e2b5d0097821dfda29ccc0b8e
d9b40dfe3ce1865f734223e66c3dc9bc01df7969
50301 F20101118_AAAEPO liu_y_Page_093.jpg
13d2078b6db827d8eda93f2fe4162ffe
d9c54d5e666842221e2c7389134d7d48af838dfa
69947 F20101118_AAAFTF liu_y_Page_215.pro
31a8b7e55f2c55afb070c7cfc4bef37e
3a35f9d7bc6773c97216bb0c751027bda56a6bb2
43898 F20101118_AAAFSR liu_y_Page_201.pro
b2c71af9ead298b8df0590be3490d68d
9ba4348e54c43391be72895c94afeb403de00976
49716 F20101118_AAAEQD liu_y_Page_108.jpg
2036edf80add5fa73596556e60bb84c7
dd15b148dc0959fd0d79d89bf8e3d5493718c49d
87637 F20101118_AAAEPP liu_y_Page_094.jpg
7c884eb492bbd56bb06f0b0c69f1ddd3
1a1cc1728dd0780b7f9a3db77d8b58264cf1d96a
52404 F20101118_AAAFTG liu_y_Page_216.pro
37967a8ec8e354eef65e61146f6b486b
edfe8ee1540c8f2d9672585a6a93ef3641a466ec
44328 F20101118_AAAFSS liu_y_Page_202.pro
e0de28c793a3ccccd798f4fa1013ce7b
3e6c26f2d1f639eca05f02ce3a40c3656ddc4219
20846 F20101118_AAAEQE liu_y_Page_109.jpg
56da6ce8e4db65e100f4d90e779413bb
e70d412201cc3e6925f909807278b60386afd24d
47103 F20101118_AAAEPQ liu_y_Page_095.jpg
83b2e5b69cadfef9a68e15c0bf515a45
1732de63f0b8a59fb4e4df403223e6b891d8afcd
23091 F20101118_AAAFTH liu_y_Page_217.pro
6e18a590b2c1bd1bdea61402311148b4
721e413a3f6eb94caf489272c847af6fbcdd391f
46460 F20101118_AAAFST liu_y_Page_203.pro
c054ab24b5dfb43bfa538011894548d3
0475af71bb670c6730d48984ff84503c01a6b89b
68939 F20101118_AAAEQF liu_y_Page_110.jpg
2911705342844431520cde29a6ff1f16
070579b4bc0ec62c69c9251ef18b347cdc2dcf14
32776 F20101118_AAAEPR liu_y_Page_096.jpg
0378d4bf1f7faca0aca295703111ef75
03aa2eeeed7fe847156e9bcabd5bea4e6ecbdaff
429 F20101118_AAAFTI liu_y_Page_001.txt
a17066ca04e8e6ecab47e4f3305700df
16ca9b0f47d41c9ddfc6fbb0dba23908cf6b3a6b
46482 F20101118_AAAFSU liu_y_Page_204.pro
093de2b1e77a254db73264fdf0cf6851
8aea5cecf05b24782c947d2ae615342348f86d05
71422 F20101118_AAAEQG liu_y_Page_111.jpg
f863fbf40965bae19611c3fedb419825
93bd24a4879d4b3bde9edd13e1937b5ed1b08c0a
59244 F20101118_AAAEPS liu_y_Page_097.jpg
5b74ae8f7a307e4868958f2b81fea75c
06b65484a08814e8f94a519c59455150270706d8
88 F20101118_AAAFTJ liu_y_Page_002.txt
241332093d85af4ce4c244d1517cdb82
8671f928bcd9ae1405b6a265d1ec74667602419c
46066 F20101118_AAAFSV liu_y_Page_205.pro
7af8eb2659c6a34eb4462f66474e85f8
3de1dfe87caf84358946fbaecc0a282af79f6729
87817 F20101118_AAAEQH liu_y_Page_112.jpg
6159c940425e810eb8ded4611396aade
7979ab1da1245c0971f2f76d22a295e14a0d1388
73292 F20101118_AAAEPT liu_y_Page_098.jpg
a4bed0e88b4f2d8b483928b9aa288573
a2e24e4bcac829078c78b925d4ce34dfea82cfb2
340 F20101118_AAAFTK liu_y_Page_003.txt
55333b276c2ecdffc3891e3f3a8dcf77
c837d9311ff696f1599492d2b4239c6e8c9933b5
46313 F20101118_AAAFSW liu_y_Page_206.pro
afab31a72c6894dec187c332663636cf
b48fc23dc102765401913349a0a9ff7e202254d2
49106 F20101118_AAAEQI liu_y_Page_113.jpg
a660f1a89e85c69fb1ca77b5e10e3c6b
3cb90b9041f4ef30b3ab8ab46e289d9cbe4077f2
72352 F20101118_AAAEPU liu_y_Page_099.jpg
b5de14231d7b5670b88c8f9be4256f60
1dffff922f06eac2b6d8a90b74a1416463b2e11a
2048 F20101118_AAAFTL liu_y_Page_004.txt
3b9c22f65af17f92ee289bbeb8d123d0
a80c42550ca81a8309ac6ceb01a6073bc4e89207
46621 F20101118_AAAFSX liu_y_Page_207.pro
c2a69c6a12778e660804e928e4752373
0ff4e6a9e5f76011810357caeca91ae01ee48a15
73701 F20101118_AAAEQJ liu_y_Page_114.jpg
7d7aed4e177df338bbfae8cad750b149
bc59b96bacfe349dffb861d54ad0bdf5548ffea2
72482 F20101118_AAAEPV liu_y_Page_100.jpg
1d678419a8835eda0c1b8bf700b20570
1f4fa7d2a09f433802dceb4199eaac923760c3cc
2158 F20101118_AAAFUA liu_y_Page_019.txt
41d3919a6fc1cd44cbade040dce8c19c
d8b6477e03d6816dd17ce67b20dc5755d7e498d0
4056 F20101118_AAAFTM liu_y_Page_005.txt
c3fe1d12acca47141c8169fb30d918f3
943ed9796c785b2ac58a61f5b0cb07e7a510924f
27501 F20101118_AAAEQK liu_y_Page_115.jpg
e6f30f7c9fafbd6eb204b28c2c09659b
949e7b47fe475d2195f51a91ceb76ae2c541d8a2
2313 F20101118_AAAFUB liu_y_Page_020.txt
8985749eaa0fa06c11c326d0357b70f2
20114fc5cbdc6c74e1fefda5a13c8de62878f3ab
4809 F20101118_AAAFTN liu_y_Page_006.txt
0a331424e14a8483744289d29ce09354
4194a86b1032d53de7ad96238203c41659fa6418
44534 F20101118_AAAFSY liu_y_Page_208.pro
d73ddbca3954a703a05471a8439bf435
a421d3eb4b89e07970460801431515b618e30542
88271 F20101118_AAAEQL liu_y_Page_116.jpg
806529335851db6004f1ac266caf0e7a
a07452b0c0e223cb2e7e882cf39ba730738170c6
65415 F20101118_AAAEPW liu_y_Page_101.jpg
91492b06bc3c3aa607ad0a9290bec83d
a55f9c7de1751af99131c7797c433792f2222c4a
1561 F20101118_AAAFUC liu_y_Page_021.txt
abf3f0a15cf945ab5b4e3134be325871
8d42a2f81b8cd5af33f7d95127a5d0f150a9ff7d
4686 F20101118_AAAFTO liu_y_Page_007.txt
8dc3996dc4be6c508e82f5da31ae5a8f
6f26b4b874923df698dd8677618175dab07bdaaa
45227 F20101118_AAAFSZ liu_y_Page_209.pro
db459a2342795b15ed756b37e8f79a4c
a6916b0f929504d23e64b09d27e2bc72196dbd66
60203 F20101118_AAAERA liu_y_Page_131.jpg
1ce3f47b86b8c721273bc29a7131c74a
fa5a15a5c2b21068172dc6725910671f730adeb2
76118 F20101118_AAAEQM liu_y_Page_117.jpg
34657cb65d6552fb3cce828c02824ef0
14b2971a1c488a15f8dcb0f5d38b599e609a1df8
69949 F20101118_AAAEPX liu_y_Page_102.jpg
2d1c8b5b140ba6591c16c5c83e27dd13
d0d05c959189db2f1f385c2b8681f33afc362ed2
1976 F20101118_AAAFUD liu_y_Page_022.txt
16cf5e202a24decd47519de1d8433da8
074be6e9a86d0fe75f49e974cb84d955eab597c9
1599 F20101118_AAAFTP liu_y_Page_008.txt
7e5daa5e027ba38b906b1bc6264540e1
a706105a158d183acdd0b61e90a5d240efc024f9
78700 F20101118_AAAERB liu_y_Page_132.jpg
abc3be583229d546cfdb6e6a62067c42
155253d703aa79f8af4ff0d7a001125191b2ade9
79258 F20101118_AAAEQN liu_y_Page_118.jpg
94bda056a93f9eb351aa09ff5174f84a
0a2afd85c6c12a5fefa8e9373bebdf57faef8cac
78451 F20101118_AAAEPY liu_y_Page_103.jpg
b794033e743bfdec3ccb1f590b9eee01
0074dfa536083eeeba5741eb59664812ba17ab79
2208 F20101118_AAAFUE liu_y_Page_023.txt
4e3a6939da1d44b7de98ba3a53b8d7ca
fc22a73a94951b2eb997173b6914f91e5fc28277
2723 F20101118_AAAFTQ liu_y_Page_009.txt
1894a4f4fd400c4cbb7f0e4d3b5027cc
008d0ad124d1598898afb9fafaef1cd02cc0456a
79487 F20101118_AAAERC liu_y_Page_133.jpg
dcce139fb9d36ed8b6771cc20dcb9e4f
16e984562ec9016dff465f449a8d9c8b6aa04389
66384 F20101118_AAAEQO liu_y_Page_119.jpg
67300448dcb325d54f8bf966e8a4519b
7f1d0974b4b8bce473f6d3a7e9ea95e96247d04e
83196 F20101118_AAAEPZ liu_y_Page_104.jpg
963bb24312cdf49a93e255c6e95210c0
14dc6a285306ad584fef5e22689b37b6d3c0152c
1519 F20101118_AAAGAA liu_y_Page_175.txt
ed73b26e553a27ebfbaa133a09e51e02
7ad3666fc0c9ab33b277213bee4b6216ce06aeae
2085 F20101118_AAAFUF liu_y_Page_024.txt
bd2c5c5f33b219d557ee1187d9081cdd
ec3089d28dbd9782bb6bbe1a5e6a848aff3a8922
1923 F20101118_AAAFTR liu_y_Page_010.txt
0b1c67cf838b822378f776226b43d304
88560b3455bb1faf4689372c2a6b3215a6fc30ad
62418 F20101118_AAAERD liu_y_Page_134.jpg
6c8305bcfddd5773eb25743f55471577
ceed421b15564817bec54989e7dba9748da2ac43
78975 F20101118_AAAEQP liu_y_Page_120.jpg
ee0350e4c016baf71a59eef04b7f4bb7
a5a54a6d45440f8aa3e188778256cd2e8c21741d
1567 F20101118_AAAGAB liu_y_Page_176.txt
3240d6a761316ab0cdb7e23af107bb0d
54950e586fc878697b1344792aed4cf06be2c395
1985 F20101118_AAAFUG liu_y_Page_025.txt
ee65d530a8507376693d4a22850a2fad
a9058599f569ed497e37403ab1d9f3043437acb5
2682 F20101118_AAAFTS liu_y_Page_011.txt
854a893d68e9d2887938f564611cb29b
b8ea29e8efb5b055742286edcd5eca0ca764d9b2
52119 F20101118_AAAERE liu_y_Page_135.jpg
0718c2b84f9085c9600889cfbff242e1
249d8614c653f5e293f3e55b03973a9096808b7e
78996 F20101118_AAAEQQ liu_y_Page_121.jpg
1f33ddddb2f53496d534c658cd002ab7
8422a7b9386cc26215752725b882ad00d2f31a2a
1651 F20101118_AAAGAC liu_y_Page_177.txt
aae7f6f8584bd35466a1fcc94c807af9
7d2c417b5617b2a4618cd2642728180edb2b3775
1708 F20101118_AAAFUH liu_y_Page_026.txt
2cd1a249b0ad2a3c8a2b24bed40fbcba
c5073b2e953e2a4fef18558651ffb67edebd8f18
2707 F20101118_AAAFTT liu_y_Page_012.txt
72a08e1a09b94da154bb1e3061e44e98
452b3012a184bb6786f652f93e6f986c3ad702af
59732 F20101118_AAAERF liu_y_Page_136.jpg
8a9391564fa507f8cf9092680d095765
257ef27f4a37b2ad700cab829b8d8dd82e9113cc
55738 F20101118_AAAEQR liu_y_Page_122.jpg
212202b703335bbacb93a1a721cb018f
5781a0fdd6d5e08a1b22ed8bf62bf4d661c447c2
1910 F20101118_AAAGAD liu_y_Page_178.txt
26d9e5bc4533f261a2b5396e6755de45
4f163dec4749381ccb2e39637f281f480f2c6265
2117 F20101118_AAAFUI liu_y_Page_027.txt
71a8e870fbfddcba3ed96d127c53563c
ec9ef102e7611ef69a788eeb24069d19346c96be
2842 F20101118_AAAFTU liu_y_Page_013.txt
539b724fe170bc11efb60753ccc3b4a7
8f8d284558165d41d5ff60f7b3c36075d76f40b5
83633 F20101118_AAAERG liu_y_Page_137.jpg
c4f991642be35b9dd1076dfb6ac95dd4
ef73502d8aacde3bfaffbcbae22f4c28793355ec
47644 F20101118_AAAEQS liu_y_Page_123.jpg
a6bd1a15d1fe0bb17e130c00d99c4b26
bd74ab1e9de5d7cd9f646d4999695e791780f6fb
1594 F20101118_AAAGAE liu_y_Page_179.txt
74e629abe5d82ff712567c7b00a24424
3fe49ab1f99b39aba85bb4e071ed30507521cae7
1580 F20101118_AAAFUJ liu_y_Page_028.txt
77d668e14d65b318dc40497562fb710e
c7d829cf3e25d8b703621d35dd274d5df88038a2
2966 F20101118_AAAFTV liu_y_Page_014.txt
1089a7d11b0b9d4e8570d786c26c65c4
47a04a0ba6b6922e5093cf7b4f93f4802da807c1
56161 F20101118_AAAERH liu_y_Page_138.jpg
2e429e0449e1cb976468566a6ca1f78a
702e2b4bf8d805968078beb679f28109a950bbd3
49645 F20101118_AAAEQT liu_y_Page_124.jpg
5c04a22a3e000cb6c564c1195898ec6d
d570de439e04b5c2a9a1b2889be30e00b94f0ad1
1992 F20101118_AAAFUK liu_y_Page_029.txt
ebb120ea1662d0e8cbb30a9ded5bebad
1799cc723ecd58abe383644c376ea1cd4cfad9da
655 F20101118_AAAFTW liu_y_Page_015.txt
dea2675195d31dbfb236b95acd943eb4
ad5453e41f94e69f88c3f81d13635544625a24e8
56391 F20101118_AAAERI liu_y_Page_139.jpg
6f8cfad492fb663efe09ad48676f4621
28ae0ee2d7cdee1a4e8f69e5aa75f6adf056d6d5
68287 F20101118_AAAEQU liu_y_Page_125.jpg
3ba07be23be8d498d5605e10a8ea27f5
1c5e2aece6051ba2fb90e92536ea2b8a5712dc19
1693 F20101118_AAAGAF liu_y_Page_180.txt
72d2eea9e2259202dc8c1892f92b01ef
c5b3f1647d353c4f78d070959a46a15725a205fb
2175 F20101118_AAAFUL liu_y_Page_030.txt
03a0389f1282a1a38827a63542048613
0cc04a6a74443d65d1d646481b7227e95af2bf32
2031 F20101118_AAAFTX liu_y_Page_016.txt
08283358b2a421edfa936b019fdfbc83
fb3ab8fd5ac410542e48424b2f54971d46ce4b7b
58680 F20101118_AAAERJ liu_y_Page_140.jpg
20f95350b4919a88e308c89e8b1bfd54
6db5f508711c4531bcad6723879dedab5efe8248
82454 F20101118_AAAEQV liu_y_Page_126.jpg
82beaf54184afc21e1a65ec3092cf6dc
7e1dd5147bf14ed4e560b192f5166a447fb58d51
1206 F20101118_AAAGAG liu_y_Page_181.txt
c77d7343f2970d76b6f81fe4f9182fdb
aae8678f0f9cc9765149736b05b47f23b74caf19
2112 F20101118_AAAFVA liu_y_Page_045.txt
4ec1aaa5a8251d6669bd436577edfbb0
8c89cd7db1ff333723b520116e948c4fd177c484
2135 F20101118_AAAFUM liu_y_Page_031.txt
8a198bcc8356511a33389db862449351
ea74c2a6a185f051f01b2e51a9492b8a242d3e93
1457 F20101118_AAAFTY liu_y_Page_017.txt
56c6144d7c79b4be47b8dbff831e6550
0639feb74bf7249a176be75dec87061c66f4c35c
60542 F20101118_AAAERK liu_y_Page_141.jpg
95e266ddb2305f6171526aba3491db77
3ca7433df26780ed43081973036b6e2d81555592
62434 F20101118_AAAEQW liu_y_Page_127.jpg
b14d072f41c6c7ae119aabcb37b71ffc
1c2f2efe1647771db3faa5719225d2b5d181c587
1677 F20101118_AAAGAH liu_y_Page_182.txt
5b56aa5a7ebcef2178b89c80b23b1d86
4dfbd9c23c7fcc4ea63584823cb7c85a5d30417b
1762 F20101118_AAAFVB liu_y_Page_046.txt
50975505e66ed0311db26a34274852b9
c93e7b4e297438de2ad71496ce80e5661372010f
1673 F20101118_AAAFUN liu_y_Page_032.txt
9bb2bd36ecc77837b40316fca28a11cf
c1e97d98a72d873b1736b043d8127f141b33f7c3
59985 F20101118_AAAERL liu_y_Page_142.jpg
e0aff2315048e5087578f82f59131ae0
121252eb558c90396d63958676b4e1f2a3e17b73
1366 F20101118_AAAGAI liu_y_Page_183.txt
8249ef924ea1f680f8e2c00fdd4d2b39
157939ec7d58625f73467b751777d97ec056c0c5
1817 F20101118_AAAFVC liu_y_Page_047.txt
36b4d8b356232ad6f55e9f2611176efc
8aef2766aa098cbff5a48e7434a2a22184a9cfdf
1191 F20101118_AAAFUO liu_y_Page_033.txt
5903f35839e7d3e5a36995e74b1cdbcd
8d5ebf441894804eb3d67f5dbcaf7de8666dd7ee
2165 F20101118_AAAFTZ liu_y_Page_018.txt
86f01f9e2657884bb5d33234f288611b
e23b6b11084a7a791ae4c2cec9af0145873560bd
57707 F20101118_AAAERM liu_y_Page_143.jpg
ef5e1c665c277f653edb41acd11f22c8
a2d40c092c04cda4d854ad33a4170e0960c43ec4
82638 F20101118_AAAEQX liu_y_Page_128.jpg
9686bec66d4d70827d16f30eca3f980a
0b9bbb004cd27f8662d20337e60019f0ded8a63b
42877 F20101118_AAAESA liu_y_Page_158.jpg
1a587896496297c3d101e8fbcabca01f
a9588a1074056e8cc7fb3788ba0a4b26430bd810
1763 F20101118_AAAGAJ liu_y_Page_184.txt
3cc547011dfd36e250eaf777d1c207c4
f38eb9d38fe8a4a129a20939c6a06fc8e325b75b
2092 F20101118_AAAFVD liu_y_Page_048.txt
691530abe835019233cd4d28544c33a3
bba30a82f26dc5cc8f332f7c7c35ed5d37bac173
1602 F20101118_AAAFUP liu_y_Page_034.txt
8f0b315ab6426f60e61fabb1ad060306
50bbdd7908ca5369cda748973d69d70af8d6ca4f
58095 F20101118_AAAERN liu_y_Page_144.jpg
ee6a900d447196b9eda56ca9027dd28f
15cb003f89ff3ea475c30db1c51ffb3f37a006ef
74604 F20101118_AAAEQY liu_y_Page_129.jpg
afd56b114b81e9f91af846806b9a7a13
4e90eb1f33d838ca3ecf02d469ca07c748bcf3fd
54815 F20101118_AAAESB liu_y_Page_159.jpg
8ef17ef7f601fab25211b819dc3e990c
2b02840a0c0a60f9c00bdcef06c27135bbcc59f8
2562 F20101118_AAAGAK liu_y_Page_185.txt
3e039989b437739fbdded1da9dc00a9b
cae4fcfe1f9de6416b1f86f2387d8b8395e35ae3
1947 F20101118_AAAFVE liu_y_Page_049.txt
7c1b51b6d043c4a0f04bdd7040b8aaa4
a95b02c471d5589ab41c9e0be6906dc1199b933f
2174 F20101118_AAAFUQ liu_y_Page_035.txt
1a5e1d1c5238549a2c86339c985bf561
b82a66e7f3c7e64e880b133814707fd90d077e5e
92237 F20101118_AAAERO liu_y_Page_146.jpg
5ec13111b41882dccd1530b55bfa40cd
7acc51faca3f68eeda950937e5a1df85adf0b44f
55844 F20101118_AAAEQZ liu_y_Page_130.jpg
4672e726b372627dcaf3791208614cf8
b5caff7b03bfeeec911e4d8808d3c234d8e36bf2
45744 F20101118_AAAESC liu_y_Page_160.jpg
91650f02f8df7260eaaac02f2056c313
3a61a43967ec3936d0a46d941c336c7641b481cf
2051 F20101118_AAAGBA liu_y_Page_201.txt
bd56b14713b3e2a3a3dc4a45f262e793
9961b9ead92d5214776cd2cfa8f709c25e6c7748
808 F20101118_AAAGAL liu_y_Page_186.txt
35e751fcd2467a0c96a3a3b56a0bea92
8bbb5f75a9b7238705b2f153e1a270674b3a5070
2114 F20101118_AAAFVF liu_y_Page_050.txt
1aa7c4ec30062ec538db7af14dd8ae03
4f00313cf3b9d55832c82dbc1a2ef0d403ab49ed
1719 F20101118_AAAFUR liu_y_Page_036.txt
245ccb884e8d78b8d9e02ddb1ff8d453
cc2e72b44fc377a29575739f22750bd478a3eb7e
76765 F20101118_AAAERP liu_y_Page_147.jpg
bc98609140f0dd78d3fa81c0f4353756
88725e339de8217e49e5e54406f9aba7e0ccf577
44713 F20101118_AAAESD liu_y_Page_161.jpg
b2139a3dc6c016c3cf890ea3b5b5459b
eab57e87a06672df99d16804c263458bdadd254c
2045 F20101118_AAAGBB liu_y_Page_202.txt
42f556e6ec669a93c3934cba530f0585
fe5a9c87e37bbd2d2e8e9339fb409b20ec073ff3
2243 F20101118_AAAGAM liu_y_Page_187.txt
1976d7d907607e334833872a41e8a195
d9eca69230d1ba8aa522e60159413f882d450772
2167 F20101118_AAAFVG liu_y_Page_051.txt
627205c8e7e861a6f27ad863e1bcfb5b
b7900fae9bff1adb65d988b5062698874bc86042
2116 F20101118_AAAFUS liu_y_Page_037.txt
53b7ada5da8f4058526ce46b89c0b2db
da7e958bc237cf1e83380abf9289b5e977b67452
79188 F20101118_AAAERQ liu_y_Page_148.jpg
962cfe17378d10414f5b5f5136f3d857
831ae5e9d0388fd1cf93520df8f0d43b230863f1
82698 F20101118_AAAESE liu_y_Page_162.jpg
5f1ab32d532fa3dbb488c3961246279a
fa0c0acf0348a1fe804afdc7260395d8e1aa6e69
2177 F20101118_AAAGBC liu_y_Page_203.txt
bb6b962e5424e19b67008c24fb3d9893
c7e07c39d294a93b4e9478a09d694a87ea6ce32b
1995 F20101118_AAAGAN liu_y_Page_188.txt
3c9080ce7923a679c07abe70d278afe6
d5fbb5af9627a756af0c45a33a876427e7ec5167
1378 F20101118_AAAFVH liu_y_Page_052.txt
9699b43a4bf909e03086c0154260ef01
2ccef4e73afe2f9334070fb15e82af2b534388a5
2221 F20101118_AAAFUT liu_y_Page_038.txt
77f6c9ba283c17e7ce8e3e018091f3e7
cd5594326a7b65d677483ffa5d9350b7c2d25a9d
67637 F20101118_AAAERR liu_y_Page_149.jpg
45b953a7438b60cfb0c1db30c4621c51
3f693b6cbc81e4e1e972e7b6af42822074c27dd7
65676 F20101118_AAAESF liu_y_Page_163.jpg
011db2336c6017271e4e7c3c3ba19c7a
f0c8cbedfa8c000ca6ae1e9d034defa9576a4fa9
F20101118_AAAGBD liu_y_Page_204.txt
526716bc90db98ef266a6fdfb6cb426b
cdcffee6851da13dfaa6c95adc6ecb8a97e413a4
2716 F20101118_AAAGAO liu_y_Page_189.txt
d81c4d01cc2d15b2818f87902ac5d810
086f3cf970d21a76aa95490c236df67bf352e4a2
969 F20101118_AAAFVI liu_y_Page_053.txt
337a760452fefd4d3242586e43cff3bb
17277f8465b94b59b9eaee16855b57f38737442f
1967 F20101118_AAAFUU liu_y_Page_039.txt
02507a74daa5cfdf7f351e9d36f736a5
2fe30cc08dfbac8abf7f2e43a87236cc0b39842f
83014 F20101118_AAAERS liu_y_Page_150.jpg
80804037874ba180ec8aca6a941c6eaf
31ba4efd4706ef6b3b53a80dc6442265aa7a90ef
78296 F20101118_AAAESG liu_y_Page_164.jpg
72d3f294181580401b87c0174cc8b6e3
671c295fa49fb1678f93fb73b72dfee93088ff6d
2148 F20101118_AAAGBE liu_y_Page_205.txt
23c24437548dcec5964b52c57492a5f8
a4f23181ef1d36cabb16bf1e2d22f1ebdee1b778
2495 F20101118_AAAGAP liu_y_Page_190.txt
2da585edd3b90a181d72b5d585c63204
b5c434060d7541053c772d9e03b005ee450cd35d
778 F20101118_AAAFVJ liu_y_Page_054.txt
a44bb72226941dc28e81a8afe6e3cdc8
2898048da1b95c7f2dc2f2fe27cea522f093df27
2071 F20101118_AAAFUV liu_y_Page_040.txt
1ea3a88e07b1616c8f7c7c396d8aca70
1429373f32cb90fe899b8c4dcb0cb7cd053ef490
67895 F20101118_AAAERT liu_y_Page_151.jpg
1a9beb69fd8e3127f73517d91c8618a6
1267a837bd33b8cc9c5931b64cb9508545e7d34d
56035 F20101118_AAAESH liu_y_Page_165.jpg
834cfcd49d0406c2403d98b5ed037316
340e30c8c64542b26cd3f21be3ff0e10a5dcb23a
2077 F20101118_AAAGBF liu_y_Page_206.txt
ec395594e1540228d65bc23d5e983e99
e28aa47d6db864c0fad4a5ed820bef8d2a3056c3
1863 F20101118_AAAGAQ liu_y_Page_191.txt
cbfcf7a28639d2d2b4494c956b03abdc
ec201439ea908c8253e95615fdfa92111e4959be
1662 F20101118_AAAFVK liu_y_Page_055.txt
cb0c260caaaf399710aef758a899d9a0
435e11a9ad2aaa30c5d147daa1ec8a5f10ec4ff0
2219 F20101118_AAAFUW liu_y_Page_041.txt
bf64ea295534ba2f4c3f3845e572e5f0
7023e8acae31ca82c5ddab3935ac18d1ae7d2fa6
86627 F20101118_AAAERU liu_y_Page_152.jpg
e6ee72cdbb0b08e4e96e5241dfff6dd1
6abe5c0794fd6d4b87e06d9eac3980ecb5985f77
74301 F20101118_AAAESI liu_y_Page_166.jpg
983de298455523f1f0e2919d51c7ca6b
7b54e16085cffe74c9331b39dd00509378527994
74 F20101118_AAAGAR liu_y_Page_192.txt
1475ad54af47b401ba84398ebb2ad5c7
6e11a6ac4da22199efef72aad68a8a8b5621f34f
67 F20101118_AAAFVL liu_y_Page_056.txt
1f9ef9586ee62a04fef208acdc3436f3
66ccdc5b3db50e89303083c117adc4656deab69f
1940 F20101118_AAAFUX liu_y_Page_042.txt
a9b972c2dbf7b5fbd143351f38fffcdc
434580209e85ebf637323eb1c7f8bf82a38a12ed
59525 F20101118_AAAERV liu_y_Page_153.jpg
3aaeb832d0fa62006ad6d8cc612d1cc2
2966d9f0335017d280c7d9471bf48a9d79ca58a2
34594 F20101118_AAAESJ liu_y_Page_167.jpg
2894653d48345c0ea14c05c137490a95
7d418d660a7433c3c6a63eb69cea67c0aece6c3e
2090 F20101118_AAAGBG liu_y_Page_207.txt
cff663e85baecb01ace922bb356c4592
99041b21652ae3d446a8d472c99a6860d5411381
1589 F20101118_AAAGAS liu_y_Page_193.txt
028672b18c68e4a5745702605b4b6910
fb792e6c400b4dc816c6714b60084329dd238409
1954 F20101118_AAAFWA liu_y_Page_071.txt
5baaaf68c8cdccb815d7b12a1f3b7ad0
4b8c9bd8f337489b09b3a8638c06ef30659486f2
2028 F20101118_AAAFVM liu_y_Page_057.txt
1b5fe38da5b13c4e96db096e58b8c0c2
879461dcab339c4a53128f0f36da570df63a6ce7
1086 F20101118_AAAFUY liu_y_Page_043.txt
f12be33ccfc18aa8df8a1b9e2d03fdf5
c04bea15d951adb75ce707f23ef11d9decb8f713
41087 F20101118_AAAERW liu_y_Page_154.jpg
cb7542748109b6e762081445ef556a98
732842de718900a11a7d2b31b0e11261f27eafda
57223 F20101118_AAAESK liu_y_Page_168.jpg
d9696deca585be256ba862e550a7915f
743c07b7b58e36a4eba5b0ae051155c32fe531c8
2036 F20101118_AAAGBH liu_y_Page_208.txt
f458af415994ea787d3339c1088ad5ef
0a83ed8c259bcb878164f334c34b2ebeacdf1da3
1890 F20101118_AAAGAT liu_y_Page_194.txt
2785d1eb402ff38708aef2ff1630c80f
65b5dce578c06e387174c11da0a2eba50c843e7a
1217 F20101118_AAAFWB liu_y_Page_072.txt
c8f53006a3e1523dcf888d0400d87712
0a8a215f7d7b8b76dfcafafcd829e0811393ba6d
2078 F20101118_AAAFVN liu_y_Page_058.txt
5c600c9c8ae77e2a643dbe066cc96479
8058b327040cecb498758b0470953e154fc5a491
1588 F20101118_AAAFUZ liu_y_Page_044.txt
c7696d2b9a98da586b61b8aa422c6652
fd06205593240b06f1bdef64cce28b2aefd7a3f3
68456 F20101118_AAAERX liu_y_Page_155.jpg
4e0aa833b15af6bbb25a6877831a7881
86923755d6d36ceeb8f04f98ca79eec91c4c854a
58568 F20101118_AAAESL liu_y_Page_169.jpg
f9ce3315c432a777d21e3b54d63e14bf
e469d767055cef4858bedaa576e151e5199b24f8
2087 F20101118_AAAGBI liu_y_Page_209.txt
14c7c1a2a927221b699f89a9c6f99194
87c7fedcfe7d7e86f734b55d38cb6a2540cb89de
1926 F20101118_AAAGAU liu_y_Page_195.txt
084ad5ec61195034b3bfc36641748cec
93e4eb8e4009898469022a709ce9e0e35c509bd4
1253 F20101118_AAAFWC liu_y_Page_073.txt
48e6c0c737367a9e029b6b8f46784e9e
9b4e6d97562be4525960ae0241fccee6c8f033ba
2742 F20101118_AAAFVO liu_y_Page_059.txt
d354a115ba42d000dec176226a5b33fb
bb787c827a02393dc504c38a35d8ac6aaa734862
63358 F20101118_AAAETA liu_y_Page_184.jpg
cd4657fbce10487c46d41802cbd06ac1
b38e3a1f8d09c9c4493052acdbd4a610934fa2f2
60979 F20101118_AAAESM liu_y_Page_170.jpg
ac5e757878a538085d7a599998a926ab
6450cb472c9c5e6302ba16402fb39940843e41d3
2088 F20101118_AAAGBJ liu_y_Page_210.txt
ea00e7c21276361877f701a0ca4d40dd
8157917d9282d9022e23a9ef6c468fd4c75d5081
1832 F20101118_AAAGAV liu_y_Page_196.txt
2bb17e8fb0772cde7317117dc89f4940
82193a38b4ed91e2b15cd262de9cfbb4410bf576
106 F20101118_AAAFWD liu_y_Page_074.txt
124cdfc1ee1005b4cb33e6c65a311248
3f7607b8f60f6aef830482ba7ce7d8089d7c69ad
2410 F20101118_AAAFVP liu_y_Page_060.txt
c1631e9b2b85e605cb5b92df74d9bd79
0b41a1350a09b0b32d1b9dea097df3bffe71903b
79074 F20101118_AAAERY liu_y_Page_156.jpg
e29d38f15ff4907b0c54f22734628242
032f8d44edace0de1eb50cec276b604b43b5e64b
89397 F20101118_AAAETB liu_y_Page_185.jpg
135b2adc479d0f8d97172131b040f63b
5821ab3ba2a6adfd131fad04dd09bc044d2e04dd
76471 F20101118_AAAESN liu_y_Page_171.jpg
9510bf1e793c29feacf024dcc7875ee0
3d74ef6709f9d27b395db975acf072524f8bcb0f
2569 F20101118_AAAGBK liu_y_Page_211.txt
06f299e33a62e147e60770580d406c87
bdc87d361d6e3093367a8b5329e0ec3578dd49b5
2183 F20101118_AAAGAW liu_y_Page_197.txt
8a1f54608d61feeb667219c1bf64a90c
baa6c1181711b6c6d01d387cd602fbffd3567fb2
2101 F20101118_AAAFWE liu_y_Page_075.txt
67cfe24430d718f5ae80692fa2483fc0
303188f265135f3a830a09ee020845423fd464f4
1948 F20101118_AAAFVQ liu_y_Page_061.txt
fba9c33eb677e2cb946ca0a57ba704fe
172429000b09fa7bec97a66d6df7534ba7a37a20
51568 F20101118_AAAERZ liu_y_Page_157.jpg
23eedb7d9e352e954c6b6a10a38ff8f8
b9cdd7bbf9f72b6ae1a655ade58cc8959abfaa72
33238 F20101118_AAAETC liu_y_Page_186.jpg
249cb17b03981a626bc06039863d14dc
1ad9ac902e5815c2088fefd565024b768748284c
60878 F20101118_AAAESO liu_y_Page_172.jpg
65c04f596c8ab7ef5448b6b3c7031704
cf320b1f20c92c63f42d233a848ab413162d647a
11842 F20101118_AAAGCA liu_y_Page_008.QC.jpg
9d9cfd614ce4ec46fbc98848c95adc02
4be011117be1ebd225043f1340a35b73602e27ca
2549 F20101118_AAAGBL liu_y_Page_212.txt
6af3e7f99f272edefce4d40b5201d8a2
2791455858c62a32e6c91b13f5311e48d4afb7be
95 F20101118_AAAGAX liu_y_Page_198.txt
b86a82cd42c2a9290d6e2631f2a33789
584a1d2a9f7af0e8fa294850ac75b5201cec2383
1480 F20101118_AAAFWF liu_y_Page_076.txt
3478af702f4f824acc14612b024f2d85
4660768374f4eba2a64778241acf2e000fbe9c48
745 F20101118_AAAFVR liu_y_Page_062.txt
e3bbb5210bd149eb1c5387edaa7cc228
c14f47d8fc959038ae5261fa75410c45845e5b92
80098 F20101118_AAAETD liu_y_Page_187.jpg
0fb16b780cd3bc6efc7740117d0343a2
d491ab338890db49ab4f725d2845a9fb0605660f
65279 F20101118_AAAESP liu_y_Page_173.jpg
8cc9cf214a8dd8a68140493858274322
2dae9757c41e9db4de302e55cf345839ffda24ce
24239 F20101118_AAAGCB liu_y_Page_009.QC.jpg
9736451cafd7a368974a59585f94c18d
925a1298bf7e37ecc9ccafb188cc8d450211e3af
2747 F20101118_AAAGBM liu_y_Page_213.txt
c034b6c955d06ab4d548b52bc9bc1d71
3bbe78f751125c7854a5dfc9051f80d8350bb9ae
2199 F20101118_AAAGAY liu_y_Page_199.txt
25ddfa224c70a81e61c33bbe4655452a
2030f5429e700d784d3fc0c0f680521f69ea6157
419 F20101118_AAAFWG liu_y_Page_077.txt
1c1362d0c5dd8d59c4fcca0f5d1a1ec4
bcd287eebe93d079fc6a55a820ea93cafcfc20e5
408 F20101118_AAAFVS liu_y_Page_063.txt
3c343e7219554109d5bd1c0d5858a710
f337f94a423e7bb66d8a66ce4e92261447fedb34
67936 F20101118_AAAETE liu_y_Page_188.jpg
c160bdc6d939733f086e95063e556a25
628b6b13e08c28ca855d5c7f0b5db1b8195b5878
85563 F20101118_AAAESQ liu_y_Page_174.jpg
c68cb80e3db9a5c10a5530343036cda4
dc9a95db3c181618b3e0d1695aee9aa2b93e7d1d
17134 F20101118_AAAGCC liu_y_Page_010.QC.jpg
4fb911b676f3fe6b69ee91e792b27cbd
0ff2841942e9a936e29680887991c27f9819405d
2482 F20101118_AAAGBN liu_y_Page_214.txt
cd3d9f35eb7a9b29df3271534b90df71
072f55f5c158cbbfb8696011e2f063803f70cc9f
2128 F20101118_AAAGAZ liu_y_Page_200.txt
1950904a637de230779d709efc708644
1c406078da4dd4ef4e1c67a6da127d6618e84043
1528 F20101118_AAAFWH liu_y_Page_078.txt
e54420381e0af7de044bdbb630aa50bf
060347025c4200d86cf904b3ec939cb05de5ec72
1491 F20101118_AAAFVT liu_y_Page_064.txt
22527b4b35aef3b26fcbb1ae9859a1d6
758b6bf0b11a7796bfa2fcb3462fa7fa07b15d22
96793 F20101118_AAAETF liu_y_Page_189.jpg
159d473889fc28ed615256783c845275
c72a4d2121f00dd7b3533f2ca2ba37aa794bd666
39634 F20101118_AAAESR liu_y_Page_175.jpg
6ffb581ff08b104d78bcab7fa6784f56
d2910d83ab529f0803c1c5e3390d85ec3c1b5cc6
22604 F20101118_AAAGCD liu_y_Page_011.QC.jpg
7deca1e70d1c1c31bd14a24d865edc64
3c62333bc413eee2699520dc2a276835dbf23c19
2825 F20101118_AAAGBO liu_y_Page_215.txt
46cbf201145af12fd68d169d728242c2
dc715466aa94ee6eb7d59774dcdf4d7f12f9cbb5
1769 F20101118_AAAFWI liu_y_Page_079.txt
9738345d159fd4896b6055117b2f1b5d
550c1e5fa7b628f59d360958ef8e2c615d8ab6f0
2109 F20101118_AAAFVU liu_y_Page_065.txt
cef1af4c3f439e4efe4c36e30f093fc3
f3e803d05c051341d60b1f53ca8d83cef1916296
89559 F20101118_AAAETG liu_y_Page_190.jpg
8d8ea6cca37e77c7aa9d03c42ffa151d
ba641feed4753920db0e6f374696ad8927e41aae
46626 F20101118_AAAESS liu_y_Page_176.jpg
31f4a3eeb774588e7d635224719a2da3
24b79a659c18fb9da85461ce918a617dccd95531
28649 F20101118_AAAGCE liu_y_Page_012.QC.jpg
e1960d1ba60d13b365fb518b511aa096
c8b708474822b0deb2972ac05c84fdfe0510435e
2141 F20101118_AAAGBP liu_y_Page_216.txt
4412f853c54a395f378c6f848b209cf3
c7e49c1d9dfd5b9a544593d3e908434d71b9feb7
1871 F20101118_AAAFWJ liu_y_Page_080.txt
929bcda39c354cbb498b826cf3a6f037
bd8b2329a71e41d8c5b6a2b55d7d748524df4bbf
2215 F20101118_AAAFVV liu_y_Page_066.txt
0524416ba9d52e7cefda4a1e2107ad3e
70610c1efd523e93f96144a444b9e0abd9747ce0
69908 F20101118_AAAETH liu_y_Page_191.jpg
47a34edda7d5e9048b149c2d0f0348d3
6aee0454f31e3742ee224ebf56bb8b5564c7e0ef
58101 F20101118_AAAEST liu_y_Page_177.jpg
b8fefdc513c2f04d8cfb9f82250536fd
d8436ee645d282d506fb7691062888c331c1e57b
27070 F20101118_AAAGCF liu_y_Page_013.QC.jpg
cabb3d2f982e37f7e0ed9cd09700f7d0
34b933be7398efbb0f6521a21fda90cc23f1800a
956 F20101118_AAAGBQ liu_y_Page_217.txt
1375754ee8c8c4c0d76f77d6466c28bb
916e6a01a9aeaa47876a7444c784c9286edc6a70
2039 F20101118_AAAFWK liu_y_Page_081.txt
eb4b81e3030dbf9887201cb5873c5a17
5852cad968f7ed3f009d7d35abd96f2c1734dfda
2449 F20101118_AAAFVW liu_y_Page_067.txt
309c8d24bc42828ba1191a2033d0358f
2489958c099fd0cecf52cbbf9ad3566af0154d08
11877 F20101118_AAAETI liu_y_Page_192.jpg
a003ed0567e6081e5c457caa36ecd662
243b14a8f761f3b63ebc2223f7d724996621b311
54839 F20101118_AAAESU liu_y_Page_178.jpg
2694fa6dbc7b752e87f792bb21058293
b24690817fbc521a218b7995c98965cb15a0e04a
26582 F20101118_AAAGCG liu_y_Page_014.QC.jpg
dfab97b6d1940238d7b3f787a8ee7561
574cbfb588bb639aa2680690148b0d7e26cca716
2289 F20101118_AAAGBR liu_y_Page_001thm.jpg
1d9a730575462117557863c447ca246b
4cfa53ea4cdc799d89a49a9fc74be9db215db7f8
178 F20101118_AAAFWL liu_y_Page_082.txt
727bc8d9caec5c22235a66b4acb3bed1
2f6323890bd39a13d7f01db87a9393749e2b8a31
2053 F20101118_AAAFVX liu_y_Page_068.txt
647fbd23c880d851fddcc591f5728699
c39d8f7573e167f8ebca92213032b1114b2be20e
38228 F20101118_AAAETJ liu_y_Page_193.jpg
15e4de51c0f53973d2f03c0a81f9077b
a5950a88b87fdac31f45ee82d3b08c5760571899
54069 F20101118_AAAESV liu_y_Page_179.jpg
037a4aaaa8dd2f054eb4dd086b9336c6
a70879b26be7109a717b1458851efc7b32d98ae4
1345592 F20101118_AAAGBS liu_y.pdf
e29af2d9c2f3cbd6c4133ae70637cc1d
c633c9fa65aa3b101e32a014d0c7d4652c5e7a90
F20101118_AAAFXA liu_y_Page_097.txt
6780efdbbc8a7f43a9b71bcba964468a
6019fbbeb11ae32a721f27bc0984d7951fb20a52
164 F20101118_AAAFWM liu_y_Page_083.txt
4982dfcd83b05c8f9381035919f3c536
1e52808a17d4da668503fee1972a77f3df8d6456
1326 F20101118_AAAFVY liu_y_Page_069.txt
b5b8773dab31b7b9cc2617201bca9fd6
c8dd6f09898f10ccf690f3a8930b63eb87250abe
30734 F20101118_AAAETK liu_y_Page_194.jpg
045daa8622347c7e60c3271fb434b2c8
a7a012dd590671de4c4b19bc10f2e6ab089f7177
54980 F20101118_AAAESW liu_y_Page_180.jpg
c9d248a6a3a0ed5e3b6ec1c04dd32b9d
21d74a0849f02107f3018d101a0a178e3ef536ad
8067 F20101118_AAAGCH liu_y_Page_015.QC.jpg
4b49426750332a700694d55d8420e937
6a0fa4cb212d5829f701f1b8a1ff87037a62e6aa
3793408 F20101118_AAAGBT liu_y.doc.doc
6596c9772ceec9b2a7fa5446b74eca5f
b62ee826f71678de098f546362ee3b9ffd67b5d6
1785 F20101118_AAAFXB liu_y_Page_098.txt
fa69595cde2b1db1425d0847e77c035c
68490c7f8f8542cd0aced1be07ffd08dea18682f
2315 F20101118_AAAFWN liu_y_Page_084.txt
7699d5b71c595deccb7310c32af1e31f
f305fd9f0dceddff7b8d204929536db879be4f5a
1507 F20101118_AAAFVZ liu_y_Page_070.txt
7c64fdf54ef3fcf4298aa4c61321885e
e1b5111a3043cae237d66a30cc7d5bf008bd909f
41130 F20101118_AAAETL liu_y_Page_195.jpg
144d7d97ff690e3b0bfefa2e37fcef36
67c843dad82550f21af4bcaf8061324abd293d81
44582 F20101118_AAAESX liu_y_Page_181.jpg
3d63efe9305dd6ce9e1bdeac78cb4477
180a764b0bbd9a24a1dfd5ac3e5eb4aba66453d1
22899 F20101118_AAAGCI liu_y_Page_016.QC.jpg
a2c95ee2e26d1f1681ec7b223c435415
83d1bcc96e12e14d70fd452d34cee72cc851ef8a
3179 F20101118_AAAGBU liu_y_Page_002.QC.jpg
eec7df24fa065ee0a897c59a53a5c872
4ecfe6143a2a1d712301cd92942ae0b231e675d7
250 F20101118_AAAFXC liu_y_Page_099.txt
dab4094460db56c079b63cb26851b14f
e3a9eb5f0df46eb78d4c496505f46e98767e25f3
2516 F20101118_AAAFWO liu_y_Page_085.txt
695b7fa471d7c52dc75a580f6a7bcb7d
9254e488c896c9fad66babd6328db18ccf2c3c21
56675 F20101118_AAAEUA liu_y_Page_210.jpg
b8c176119adca2a4ca598b05cecc0d3c
4ad63daa6630ed5bf0c06c6a08aee855a64c3312
31547 F20101118_AAAETM liu_y_Page_196.jpg
26911d17706813da4e8dcf5ddaa1dd78
e9a04fa2bead727a557f85aa0a5d514d1f88706e
47468 F20101118_AAAESY liu_y_Page_182.jpg
82476c98ee8be0919202c50e397ae103
4f7400a323f5423276222745a096280876e1257d
19754 F20101118_AAAGCJ liu_y_Page_017.QC.jpg
ecc77b1aae6c68c5b1860ffc875f6ece
1778b38ce765ed304a899fa11c05a866b236fb41
18 F20101118_AAAGBV processing.instr
b0f16c7251434559ae1e7aaec7471ff3
f4cf08ba70239ae1eeff611d72b24a1744c1db7f
249 F20101118_AAAFXD liu_y_Page_100.txt
bca3b822e3d7475876ce6aa398aa9bf9
19f532eefb26ee82440579fa4e1e3c726855b8ba
681 F20101118_AAAFWP liu_y_Page_086.txt
9f87ec6ec6422906cc0fde32e1b86c10
fb6490e7c359ecf7e3c3d1533f2d8315e059fbae
35772 F20101118_AAAETN liu_y_Page_197.jpg
8630aa94984206245b580b630693c3d6
3894b9ee1fc531a8ebe6b01868d1294f4eb5d27f
100249 F20101118_AAAEUB liu_y_Page_211.jpg
99ea63bee754f28b1335fccea74c8a4e
3725b961a23c4f992ed824c67beefae01ada966d
26057 F20101118_AAAGCK liu_y_Page_018.QC.jpg
2b6967f5308ce9b4d101d8b3ddbe3122
c5fc51e749d72ce0d91bb1548694c0f19a6a5493
5696 F20101118_AAAGBW liu_y_Page_003.QC.jpg
bba82f86bb725ae4310e611a578e42c5
21dc4a7d0b1a9e2936b8c5b9e28a1736b3ebe709
1740 F20101118_AAAFXE liu_y_Page_101.txt
846a8ba469c17f8a2ea30991d6541fa7
c06b6e686f2235da25c0a634b463b800c06cb8af
434 F20101118_AAAFWQ liu_y_Page_087.txt
6cf3ac875181ed78847eec1b3842b585
bbb28fe611d77120633c5c646c5c918e546214c3
12851 F20101118_AAAETO liu_y_Page_198.jpg
461e1392f5f12fca8cb33c244144d606
a37579f50ff81d5b81a2c319af4265b6090a6340
48281 F20101118_AAAESZ liu_y_Page_183.jpg
7d2475b3dcfacb9505eb45360c6d8a23
679904606feff4bfa248603d9fcfcb45dfde30f8
102882 F20101118_AAAEUC liu_y_Page_212.jpg
c98e1868fea7d8085fb8fa88b0c7c19d
0aae96f8d1a846b63b24fe7b837f5d8c89f29100
7190 F20101118_AAAGDA liu_y_Page_027thm.jpg
4ced4e4ac15215ce2be26cf5f4960e81
859971429687f0e00a4bf075a5365fa36dbb1425
26384 F20101118_AAAGCL liu_y_Page_019.QC.jpg
c6be245a82e8da6e0fbac9c87f8c19f9
5f2b4123a175d7a269bc3663383d020fadade4be
6199 F20101118_AAAGBX liu_y_Page_005thm.jpg
2541482d323024a21af25f981e198414
57e0730b1f87039086d37ce057d734cc645e3c29
1885 F20101118_AAAFXF liu_y_Page_102.txt
25f40c6a70baa7ada70a100314fce512
b6e7ce161342e279e6ccf28679d446e623178fea
1216 F20101118_AAAFWR liu_y_Page_088.txt
28fd6b23acd4c3d83bdf563d7b4abd1d
561844999cdc53ff32f09e6d982aecc37201c130
58291 F20101118_AAAETP liu_y_Page_199.jpg
678ad2bb8fcadd9618507538af1c3bbb
b290f81cc021e6c776c0d65c2d4fa98fa20745f8
110283 F20101118_AAAEUD liu_y_Page_213.jpg
a721c1938cbb92614f7873b690f9ba62
9a626fb379ce0f93859033d953ce672d96a1a277
20167 F20101118_AAAGDB liu_y_Page_028.QC.jpg
2b2238db0bfb6629d93b7d6b8c92ef27
4c532323285c3e2c58625be215a40d3827aa8bea
6743 F20101118_AAAGCM liu_y_Page_020thm.jpg
a94dcd948ef778b7142375ccac5ea395
9c26266d2e820f724166b96116fed6257b2a4211
26854 F20101118_AAAGBY liu_y_Page_006.QC.jpg
bdca78e3853ab9d625d175b37b588f47
84c2b177432d54979bedaf41214f8c060891a348
2093 F20101118_AAAFXG liu_y_Page_103.txt
795d92bf494d35984e6a6c4b0f197d39
f7371e73bdeb8c6b30a6aab0307fe77c95c1aff3
2256 F20101118_AAAFWS liu_y_Page_089.txt
a89d101048ed0a406d98f8b58d2f5c25
1548b5f951037aadf7fdec1280ee75fcb3a75727
56128 F20101118_AAAETQ liu_y_Page_200.jpg
d6369dfd9945fcb3df6201b56c98b59b
b0aab245a6ed35fdfd4cddad38c985bac8aeda66
99563 F20101118_AAAEUE liu_y_Page_214.jpg
865485f78080649d08dae0a99efec9d5
f25bd15a1d3622add6f43952c0963261247e50ea
5747 F20101118_AAAGDC liu_y_Page_028thm.jpg
309ee3a1335e9dd2ba93e5d0d8bc5bd7
de8b733b788fdfcc335334230abd15584721e981
17358 F20101118_AAAGCN liu_y_Page_021.QC.jpg
e5c03a100524bf5a47c769c41b85f1e8
3178cfb4091aec46a0dbbe04affb3f94e4e45b88
30474 F20101118_AAAGBZ liu_y_Page_007.QC.jpg
6ade8937dc1e2747384efaa5c2baa9ef
1677b0e790581f37fe8d1ac86ba332d8fd5dc2de
2094 F20101118_AAAFXH liu_y_Page_104.txt
ac318756bc92814260c149a6c9ee6216
30a00c1b57aefb386975ec4f058c12559797a92d
584 F20101118_AAAFWT liu_y_Page_090.txt
de6189c958bd675359f7195fd3aa54b2
12c73ee80417c5f12adade534fd2e741cbde6ea1
54580 F20101118_AAAETR liu_y_Page_201.jpg
e1a6a975e3077897730978cd761fb209
e4a45cac7fe6e299932068b4c789d8bba1da7034
1051961 F20101118_AAAFAA liu_y_Page_149.jp2
00e9793351db5b0c1163895c2c0a606b
771f017f012e72ae02353c3dc0de0843b51ffd98
107541 F20101118_AAAEUF liu_y_Page_215.jpg
762422defd80fef2f332865d9fc43e6a
6cdd06d8688b7d89f21504a4ddba7dfb7361fc07
25168 F20101118_AAAGDD liu_y_Page_029.QC.jpg
976498954a5626911208c428fabd9476
9076a36fd983f3d861dbaa98cd4e1496132da612
4812 F20101118_AAAGCO liu_y_Page_021thm.jpg
0a45141c7faff13f930547ccf9737eb2
ec452d34bd9de3d020a0e5c8bdf9e8a5f895237c
935 F20101118_AAAFXI liu_y_Page_105.txt
041daccfd818a2853b99e303153b174a
12717667d2caaaf0600001111983299addd572c4
1675 F20101118_AAAFWU liu_y_Page_091.txt
80c0252de030530eca0587fa311fdef5
18ccf3fd025a9bda99fc80268158639364b82afb
54825 F20101118_AAAETS liu_y_Page_202.jpg
a61661f1bb58c43c6ce2df3a18098f7c
396e1047041b2a7d33943874fad2ff3fae5516d0
1051978 F20101118_AAAFAB liu_y_Page_150.jp2
7b0a208cf34cf8efc5e9479a5dee728b
fc6c59b4f7901962c895dcbabe7883596d81589f
84088 F20101118_AAAEUG liu_y_Page_216.jpg
f56f16253f58b312ea7ddc35368c69e5
682d217193978233180263b23c67444fc6403412
7054 F20101118_AAAGDE liu_y_Page_029thm.jpg
1d2e21e4a9aeedcf1c98b13cfe2d1e89
da088eb787ec95b6dd0bb77b1364964f7ac7117a
23693 F20101118_AAAGCP liu_y_Page_022.QC.jpg
1c84e70d092151150b8d77cd452a3b13
96e2ac5adec768fd03ea8c54a74486fca3125256
2938 F20101118_AAAFXJ liu_y_Page_106.txt
9eea04b723054654600ac05f41855e14
454bde263522634e32817173e4560af2454374f7
1653 F20101118_AAAFWV liu_y_Page_092.txt
b87df8d5ee2be51c7f72db987bccae24
9f8ff84ca6b2f9e23ca5aaea7610109ea35deb35
57067 F20101118_AAAETT liu_y_Page_203.jpg
085405ac805b82cfef61bbf0f4755478
fd2f6347ae4b1a36aaef404f70b34fe85091f95d
1051986 F20101118_AAAFAC liu_y_Page_151.jp2
2f7daaa849caee828221d3af71b92f6f
f69d85052b1947b026e109661a46278bd1bc2a97
42987 F20101118_AAAEUH liu_y_Page_217.jpg
2a36ec0c2abb329a2b2ddee733f2787a
67c0c11249a157bba2b9178248a43b8635c12480
27658 F20101118_AAAGDF liu_y_Page_030.QC.jpg
04ae747b86ecee4c73aa5a3354e3cafe
c1f6159bd6d4b61787fe707e97d04b6bb40740f0
6633 F20101118_AAAGCQ liu_y_Page_022thm.jpg
c032c5096c1270cb017509b9f20423f8
fbd66f0e4963ccf5727f1c14716cbb55bc5c574e
1056 F20101118_AAAFXK liu_y_Page_107.txt
1f38607489c0630a0d51d958e75b9057
a43d1fbb9826838ff3c638071f87e85129a7a367
1158 F20101118_AAAFWW liu_y_Page_093.txt
c770a9af6e28820948588fa5b3832d78
f80c84bc3418bd30f9235762de43bb62484d1cee
56850 F20101118_AAAETU liu_y_Page_204.jpg
4a4dda44acac488a04cc3dd03431262b
22522f90cb9642bc71057fa872344093adc4a5dc
1051935 F20101118_AAAFAD liu_y_Page_152.jp2
2f0a6a9f7dd82934d87f7d5e2d2a28cc
cf5f5b3ded4487ddd977bd5d44cee5566c091311
6451 F20101118_AAAEUI liu_y_Page_003a.jpg
a46ddb986f23eb2facced9975b9a75f3
e561b3cf07a45e6338f2902d330785fa2dd9ea28
7421 F20101118_AAAGDG liu_y_Page_030thm.jpg
7b690757db9ffceef152313bc1914ce1
f9566cf54dad7d87c66498900a7fb3662195de66
27733 F20101118_AAAGCR liu_y_Page_023.QC.jpg
39bb77faa8c86e0920a2ce030884aaf6
4a249a24412c7a642c16d0bcae9302f420895536
981 F20101118_AAAFXL liu_y_Page_108.txt
df5bbfb915665d789cd0cdcc8d14a4ad
8f71a81e6748f5d2d352e730eae2f58f40e677b6
2849 F20101118_AAAFWX liu_y_Page_094.txt
95c8f3639377eb0626bc00312cecc315
7665d77e55bced352568fb564c481823f65abf44
56333 F20101118_AAAETV liu_y_Page_205.jpg
b206a61cf10e9c5d2c0207d1e4f375e7
9bf58a11aa8dc244d732f6f5d1b6b58c807403e4
886977 F20101118_AAAFAE liu_y_Page_153.jp2
6b77258a32947b16936e99f31d0f2975
00b4170afb39cc8225c71b496a22b90ed6e57193
228978 F20101118_AAAEUJ liu_y_Page_001.jp2
ec47555db6b470e0f52b33e289f3cbad
b9370c627f7fd03e0df687ef7eebdc03e06b287b
27463 F20101118_AAAGDH liu_y_Page_031.QC.jpg
402fc35f4e9278db36d9f6cb3efc9391
b2a925054b42d99f7125f7ab0f42099a4baca10a
7416 F20101118_AAAGCS liu_y_Page_023thm.jpg
880dd2752452a4f8afa914d3ddcfff78
103a20b66c577102eb55b38d5f037dd031e90f34
F20101118_AAAFYA liu_y_Page_123.txt
0fad086fccdee5710f13283fcb6f44fe
bb637f10c6427b1ac447fbc6d5f9fc51ea108b43
382 F20101118_AAAFXM liu_y_Page_109.txt
44306bbbab0a69d06a70eb1433aff4b5
a20b6d5e2a7aea57511238f37575bba9c63eea62
1033 F20101118_AAAFWY liu_y_Page_095.txt
1757635e9ccfc26d4b5773034b5a9567
2a5927687d6da0d9459834bb1cc6dcd3e59a5cee
56245 F20101118_AAAETW liu_y_Page_206.jpg
6a9ae887ded8781e740d06cf6e04291d
8be76374b5a104086a7335984812fb0327190443
677130 F20101118_AAAFAF liu_y_Page_154.jp2
9a0c9403ea1528ffd40a12739fae7dda
74291ecc3eb89f1c2885c810ba52b5a4c3bb6fb0
21489 F20101118_AAAEUK liu_y_Page_002.jp2
84807a1995a628960bad77e8cfeb7b04
acf91d3789ee92986a25102d7adc57d49d31a1b6
25687 F20101118_AAAGCT liu_y_Page_024.QC.jpg
3bea5761b588158f18b9ef4300084275
0f246d56c081f35d1835648b01da7111c3889bc8
3010 F20101118_AAAFYB liu_y_Page_124.txt
c757fcd3f4af3930b86e54b8a0151e3d
5dc604180e42e929a2ba79ba775d55ac39203156
F20101118_AAAFXN liu_y_Page_110.txt
565ef69c46f879ddd6bdbb1e279615e2
b94ab7419cb5aff27e1fe7223e892403141da352
862 F20101118_AAAFWZ liu_y_Page_096.txt
6bf1c91f8a4b7e67ecc0e850dad27d5e
446c33c4c8ab66658e596c2f5babc1ca6fceb87a
56251 F20101118_AAAETX liu_y_Page_207.jpg
6f1ffa1e4605edfc4ffbf8c29928341d
c135555aae7e4d85f600df7157129530a58a8998
170069 F20101118_AAAEUL liu_y_Page_003.jp2
c0334b7493a012a5eca4703815eafbc8
252ed65fa95f5c386d6312a0fb35223347e2858e
7342 F20101118_AAAGDI liu_y_Page_031thm.jpg
7bc6f3f7ab104c54e324044d6221e30d
022ba2c889567eddce23ecf482122d7d5278a798
7020 F20101118_AAAGCU liu_y_Page_024thm.jpg
e3575164520a03af5111b872d55bf4dc
0f253f8a76c68b153bd2e0871fe8a3ea9d24f024
2054 F20101118_AAAFYC liu_y_Page_125.txt
ae624e255b4262b0443d842379e666dc
027cc9dcbcc76a165191722b61f3fe7474cb62a0
F20101118_AAAFXO liu_y_Page_111.txt
a9abd63f34c20440ce6379fb9c1082f3
0c578760d46beb380597cac43e5181e751084272
54233 F20101118_AAAETY liu_y_Page_208.jpg
87edfeedff24aad128347d2551c924da
cf4f69b11077fa3e4635756581df1e6fc9673024
971802 F20101118_AAAFAG liu_y_Page_155.jp2
e54698894ecd3e05d51db898c6131764
fd1a91e601864a466d538d3bc5e9067bf24ed65b
1051895 F20101118_AAAEVA liu_y_Page_018.jp2
c1650a007cd8839666fb4a92140315aa
60fa6be134e35dc94eb250daab0565640e6cf6f3
F20101118_AAAEUM liu_y_Page_004.jp2
7765ffb553119607a03aef37a041a4eb
a543b31ce12f7c36025e81b16764198fe8bd8ded
19379 F20101118_AAAGDJ liu_y_Page_032.QC.jpg
bd656730e8ca574024290b188eeecdc7
044d60f8e18446b7ff783216b73c316f53b4f62d
24309 F20101118_AAAGCV liu_y_Page_025.QC.jpg
71cceb106ed2bd87bc229d950521d628
d247aca36a6ab5c139409e1e90d0f586a61871a0
F20101118_AAAFYD liu_y_Page_126.txt
297a8db9328f97a9bfd1673baf0139c6
ef20245ee204392006f921d9c91bdd2f47f6b686
2225 F20101118_AAAFXP liu_y_Page_112.txt
3b1eba06d72d5904d6ce5bd22f654f34
457474de344074d213b9a2cd94634f9ba4bc7e53
56587 F20101118_AAAETZ liu_y_Page_209.jpg
afb9bb6462b50437f11ac33278539441
c16ddb38c42dfd64a0aa7ab58b1fc6f8af7a0023
1051984 F20101118_AAAFAH liu_y_Page_156.jp2
6bba92f53aec9269b6ffa21aeeccfe1b
100c9bb7ff61ca76ba4e93cd087b8fd975a5dd61
1051948 F20101118_AAAEVB liu_y_Page_019.jp2
4021ee9eab413c1e0eecf8ff0db4360f
cb053a12259eb1dd100169cda4e8c2046a3a2e80
F20101118_AAAEUN liu_y_Page_005.jp2
432bb66ec9e0faf8006223a406b319a4
7f852249f48f6b031813832be23418d7f6c18ce4
5680 F20101118_AAAGDK liu_y_Page_032thm.jpg
27f48929bbcdc52783bb518a9e343998
2fc9219e474349e2267000d3999b9701616953e7
6818 F20101118_AAAGCW liu_y_Page_025thm.jpg
1d49bea12ef578e0c9b46922e450e00a
ef9910b565a1135a79dfad88b6c798e5cf7285c4
3121 F20101118_AAAFYE liu_y_Page_127.txt
f9e307443ba445d530676b20f289577b
19ee8e0ac8276135b590ebccb7e94b5d13aeb880
1331 F20101118_AAAFXQ liu_y_Page_113.txt
4c3b74ffe25bcfa2f3c1947808cf53d3
88254aedf5d41a89d5f488b8514ad6576d12adbc
676755 F20101118_AAAFAI liu_y_Page_157.jp2
31d49090b974642701e913e1088e9a27
ada29236887e978f3764005d570f7ea81e7c98e3
1051839 F20101118_AAAEVC liu_y_Page_020.jp2
a2faea8e1fdd579bc69a13a07e22ca45
7df31f4d04927cea3ca5dfd05b9e9967daa0e2b6
1051955 F20101118_AAAEUO liu_y_Page_006.jp2
18006786dd6146b802c296ae4ce6899e
e208b22fd4b2ae8e57db6cdd2bc47a4ff97d7a91
7174 F20101118_AAAGEA liu_y_Page_040thm.jpg
19b30805100973a7aa783ed7a1bffa14
b9f1ab77988d556814a04f726dc11aa7df8253b9
12698 F20101118_AAAGDL liu_y_Page_033.QC.jpg
af73d4ef9b0ffe05bf0a1800283f6b1b
18374f8b8806c060ed22168adc842acece1f221e
20609 F20101118_AAAGCX liu_y_Page_026.QC.jpg
8f43eefe27ca1d95613e7a8cdd6d48a3
c18dd0d5843f7707cf370b90a231e4b67f6d893b
2043 F20101118_AAAFYF liu_y_Page_128.txt
721c15b028d9183308d8aab7d8898920
68199f15d9b4843e254131cff01f5d7f60ed0d67
2274 F20101118_AAAFXR liu_y_Page_114.txt
4b4078cc2bea0b1048ec83edd27567e6
1434da9e5e0b120fe3e1add01cc24e8031ae4f09
530007 F20101118_AAAFAJ liu_y_Page_158.jp2
dde9ff8feb847e50caf6b75d88a027fe
1c293f79d8b9bbde394105e1b9e8264b48b4ea9f
809754 F20101118_AAAEVD liu_y_Page_021.jp2
9fdb8c867d44e5bbec3267a6c3adff3a
92acd07a321fcd083411ab36e3bee15f69d5e91c
1051975 F20101118_AAAEUP liu_y_Page_007.jp2
9e66f20e50e35ecde75702117db69601
965e7a2533bb824b8441339b01ff57dbb9b2ff5b
28137 F20101118_AAAGEB liu_y_Page_041.QC.jpg
3600436fc991233ea1f3f79f889f41cc
d78b571510d011461fc1b4924f641a9fabad6834
4152 F20101118_AAAGDM liu_y_Page_033thm.jpg
6e2d9c87f0548e9e20ba4e58ea934809
ed7bc24613279a1c484ad78ceb75f082cc60f16c
5880 F20101118_AAAGCY liu_y_Page_026thm.jpg
d3d23439410e096157074a3ff8b9a775
c6cd95fc16c0ac34c9dde1c8d760d48467fd3a22
1565 F20101118_AAAFYG liu_y_Page_129.txt
2f054dad2e2a64d2de72e8f3573819ec
ec287309d53433d102e730f134e20c1be5ad4173
551 F20101118_AAAFXS liu_y_Page_115.txt
dfe285af84e4a7dda5ea10254b7c750c
4f0a445a034d81b62d9df5c4acd694d23d95c73e
667223 F20101118_AAAFAK liu_y_Page_159.jp2
de66a5e7c2f994a0aa85ab0601763fa1
4bf234aef5065dd13763a7d1be952f51294e691c
1038058 F20101118_AAAEVE liu_y_Page_022.jp2
c1935f095351ebf06e197c032a30d97f
6922b34f55c9ed5b2a3a91e3b1cd9329bb7c27a1
1051970 F20101118_AAAEUQ liu_y_Page_008.jp2
4f9c664cb2192e935b00e1d04885188d
711319493a3c6c9a70ed2a3975f9a310b266af95
7339 F20101118_AAAGEC liu_y_Page_041thm.jpg
da09a19e9552cc2335de7de52dcf08a3
4eef87466aae2aedcdf24ba6e3917aa6ad37aeb4
19333 F20101118_AAAGDN liu_y_Page_034.QC.jpg
fad21858a78794cff5256b43a1d14de7
3cadb043022d537f872f5f91722433a83413224d
25754 F20101118_AAAGCZ liu_y_Page_027.QC.jpg
2866498b741106ec8fbca4fdc143dae9
7faa36c8e7549c11d19df22a503018a2e335a497
1572 F20101118_AAAFYH liu_y_Page_130.txt
e1131b25f035d8efd2348ffda30ef52e
8bb85812fa72713eebd913284e1cdcd9c52ad350
2688 F20101118_AAAFXT liu_y_Page_116.txt
78ee26fe08a83decc2c52c27c99c068d
086ec9eff5f9576fac93c5b70e80820e5d3a13b1
512703 F20101118_AAAFAL liu_y_Page_160.jp2
a16b1499179b60fcce9b5b861577c617
a355e90985e3f16f8abe7cc22b614f390ecf9d26
F20101118_AAAEVF liu_y_Page_023.jp2
b2cee6b57f6b6c97b3894e9e7c66d209
fc7e74db0958ffeb90fb8b13a2c075d3a812bd17
F20101118_AAAEUR liu_y_Page_009.jp2
d19483d280942a2a60e648fcfd94ea09
4ef3228ab7bb473bfca24bb420b4f699df26030f
55399 F20101118_AAAFBA liu_y_Page_175.jp2
b15ae41421fbb3b07286b6d670f77a8b
45ac97e5cceeea470342ee0b777117d70a2c2136
24595 F20101118_AAAGED liu_y_Page_042.QC.jpg
02c110c18aaeab131b60673a0b6c3769
450e0ba3194961a8c72a16667c6909fdfd022bcf
5900 F20101118_AAAGDO liu_y_Page_034thm.jpg
3a9cfa52f9dbba19906eb39754b006da
1efe968cf7b30bbc8d20c12fb6bf07210fc945f0
1767 F20101118_AAAFYI liu_y_Page_131.txt
292d83e9579f1bbb49c192cef4af5dee
708ffa9a83ba55a11ac43bb64d9e12bfaedf6f8f
1473 F20101118_AAAFXU liu_y_Page_117.txt
5ef324cf3d677549a261fc92e65b5c65
ad1aca19ba3a26c19091ff0a2c47e7f54fb07734
533475 F20101118_AAAFAM liu_y_Page_161.jp2
b8c9c5c03f1bbe68ab33659e1f2606d3
d9c01bc27492c4888edf06728f9d95ed73472e37
1051971 F20101118_AAAEVG liu_y_Page_024.jp2
a8aff075472412f3e0643294b58e1648
a33a709492b206b4237a3f9ae74e46f91c827b26
F20101118_AAAEUS liu_y_Page_010.jp2
e9af7fb7bdeacca6a5cfd28ed7dbeaa4
c8096afc21861bf573a90f34da33913a05e77ace
588711 F20101118_AAAFBB liu_y_Page_176.jp2
0dd842ee3a973c465cb1a441e3a6629d
d89ef888cc3cbb37dcdfc04ec17ffa8d5b283dd3
6733 F20101118_AAAGEE liu_y_Page_042thm.jpg
4184e0a2cebca52afcb77500ddc9c1c3
306b45f11da3a3ab13e3136c5b48e1d542d3e76e
27228 F20101118_AAAGDP liu_y_Page_035.QC.jpg
687310cd4199c7d6aa917b7193fd4284
72a5718efecdc8c5749c31f3cfaed5b53303a9ec
1876 F20101118_AAAFYJ liu_y_Page_132.txt
3de8fb9c84bec2f356f0fe9481c9a7a0
9118f7a61d24dcf782e0eb83d54fbbde12b2672e
555 F20101118_AAAFXV liu_y_Page_118.txt
58feed37e091d25c356141c46fdd5af4
618551aeebf724de9dc71fa8d3733381b34b2d99
1051934 F20101118_AAAFAN liu_y_Page_162.jp2
f7a7017b8622658eb52f22933f270f20
a36df4925158a9ac2fdf525b1150f7642cbd8443
1051980 F20101118_AAAEVH liu_y_Page_025.jp2
355230bda0f5872626491174d569f28c
af7df03840bb3a31dae1bd1fe24930068f3c7943
F20101118_AAAEUT liu_y_Page_011.jp2
e4df2f835b76c8f3c6d1554c171dcc96
b332106ee38ccac00dc8eaa8e0c31fb9a6432bfb
806917 F20101118_AAAFBC liu_y_Page_177.jp2
f5837cd9f9f9f2e39c9973be195058ff
1b10cbb7d6eeca0329f622f6afe66859950580e3
13059 F20101118_AAAGEF liu_y_Page_043.QC.jpg
3c24caf56a4275143900fd3c378f34ab
4e0d9deb1f2dff863810be01396a342ada69b045
7476 F20101118_AAAGDQ liu_y_Page_035thm.jpg
6a1a11a1422e239db82d586f4d0f789e
b4eac834a8b269e3adc0692203e488f7ceeb4c9e
2069 F20101118_AAAFYK liu_y_Page_133.txt
e0dfd40260a6914dfb0c6dea81fb01f1
54672720ff230bb92b62cbc8e189813c6860e8f4
1154 F20101118_AAAFXW liu_y_Page_119.txt
290a7fef1126fd8f23dfae1ea86df5bc
4770a1a6878a1900aab979db3886fe45222f081a
1051952 F20101118_AAAFAO liu_y_Page_163.jp2
a9ae939ff1f695197df7ecec8c7f7cd9
56d9cd0c2ee5d890451e0c8df2407a8f4ab69795
87023 F20101118_AAAEVI liu_y_Page_026.jp2
efadf2d57428acf57365a2e33f505f3b
d5f6ae1d04357c9b8302c4f3269af35f74c9bfaf
1051937 F20101118_AAAEUU liu_y_Page_012.jp2
58e466bfb5724e63dc7922070ee26848
5628da7600f95b593d6059dffcc7a41131edcd4a
694726 F20101118_AAAFBD liu_y_Page_178.jp2
2a123d2facf4ad9a6deff96b4ee1c55d
7383cb2fc2c373359eed57414b6e1ac67bab96cf
3966 F20101118_AAAGEG liu_y_Page_043thm.jpg
9335bc5f79d6f20dbc90aedac8af63d7
797a4bb2a0fb8b80fbc075bc78e4a5e654217534
23808 F20101118_AAAGDR liu_y_Page_036.QC.jpg
9448cb8387af8bd2cd0988bf38a966d4
7990281336a6b3ce0c1d14fefc2ca818b3b9e77d
2305 F20101118_AAAFYL liu_y_Page_134.txt
5e2f81ad5d24da442ef16876d38d5969
3e0e62db0c5122fe620257f9d30635771f3a0be6
2020 F20101118_AAAFXX liu_y_Page_120.txt
7882786bd870fc27883e0957171d4ac6
e517794ecaa16f9524ff0878720685dfa50ecd92
F20101118_AAAFAP liu_y_Page_164.jp2
5c45fbeefeef00d0b4f5e34b6c982ddf
389a538e36945f23588d727cbf63377815e45b63
1051922 F20101118_AAAEVJ liu_y_Page_027.jp2
e1021311faf35b7c52a13b3dd173f5df
59160a13cbb925ad3a48448e460da9378b871f09
F20101118_AAAEUV liu_y_Page_013.jp2
dd298d881cd047991800b67bd9919c5d
5e2977c6b1ac20851f87505de679329322339b1f
728508 F20101118_AAAFBE liu_y_Page_179.jp2
dff7d8199feb923556981545ac33eb04
d6bdc6e94235b434856a2f2ac894e6c2499b43ea
17100 F20101118_AAAGEH liu_y_Page_044.QC.jpg
806e840511902e7b5dd5be24ff45ecf4
7d177995d5f2b69204d29d6d739d2fbb920eaedb
6615 F20101118_AAAGDS liu_y_Page_036thm.jpg
178508166e6252004f5d8de82018e396
128964f64e2256a2b88700ab3c101cb4500fd7ee
F20101118_AAAFZA liu_y_Page_149.txt
d9ffa7c6d70a2565c3a38e55fc2e1d17
4a4e117f87899f02b5cbe389439d24d3f1ff3bae
1808 F20101118_AAAFYM liu_y_Page_135.txt
a743e1e6ffab537775476ccddb32c495
f5b2dfe4a2485c7d0e26289ace95c68111340af6
2160 F20101118_AAAFXY liu_y_Page_121.txt
f71aa9b0bf316fbcd3fbef0977822464
806b94dd8ea5d31b059fc55661c40e8d5e1c2a5d
752723 F20101118_AAAFAQ liu_y_Page_165.jp2
bf122d7e5bf7d6e9e2b1d94118f172ce
607a9bf977d6c49e9255cd9b2f697c9689c3b786
84341 F20101118_AAAEVK liu_y_Page_028.jp2
ff4936baa1f8820d837ddb7f379b01b7
0c8875c7b2951cc38f653474d6641793255a16ae
1051982 F20101118_AAAEUW liu_y_Page_014.jp2
52d9bc28c1277d3665d870be4d5888a4
e0c449756f25fc524e2eb867512e216ec9078f2a
683799 F20101118_AAAFBF liu_y_Page_180.jp2
52bc5ab6e1f85fe3e884f340812d04ef
cad56ecc47b53e4bb69444783761fa7dbab59cf8
5185 F20101118_AAAGEI liu_y_Page_044thm.jpg
33d58fe0c7290a0c95462a7011a4f735
2b773d523f58352441d8b1541a01fe71c4f5744b
26663 F20101118_AAAGDT liu_y_Page_037.QC.jpg
5c32a83af3d4a28aaf8aa077a92c0695
db96fff2ad3f38d2ea6ae2fafa1c3547beed6bb1
2021 F20101118_AAAFZB liu_y_Page_150.txt
7f8e9a20d2688e6d67e68080a4a85499
2a5702f319629c0d77f7b65fd0135dc4298f2c53
1724 F20101118_AAAFYN liu_y_Page_136.txt
ed8194a367d6af1d6a9fe6eda13b9776
f9964ebb92d93f3bfba8690af9320d55f1102747
1584 F20101118_AAAFXZ liu_y_Page_122.txt
0278a0c875c4a2346a735e71b76fa46f
6ae241166429dc9c5efb81a7ba6e85bbf58b8ba5
F20101118_AAAFAR liu_y_Page_166.jp2
c70bd88ecbca77f12adcea8c94eaeee4
1c954b08a25d5ca35f595383b5aef91ddded5640
F20101118_AAAEVL liu_y_Page_029.jp2
2399347760b23142e9c6f17128064ecd
5fe2ab96ba583b21ec5db59bd3767277a31fe46b
612952 F20101118_AAAEUX liu_y_Page_015.jp2
94e8f2a41c2435560d0bb502d1793fa5
dfe67fa1428b3c03d32c2e481174e6abc49f4747
551225 F20101118_AAAFBG liu_y_Page_181.jp2
6f0efbc3dae29ea89a66b8d5c8a1bf2c
3e9602a496f850f88f299835951cfcd8511d6430
7142 F20101118_AAAGDU liu_y_Page_037thm.jpg
7102d91351789666d3049636b321cb97
b260c2a9e23184d1243f72ca75625e4a6bc7e24c
2244 F20101118_AAAFZC liu_y_Page_151.txt
620136470d68f57c04951b97965d5396
56b95e5aa4706318d0512056245682b247876477
2246 F20101118_AAAFYO liu_y_Page_137.txt
c3af722a82441dad56fdf64c1168943d
fa81a3672a8afc362f0d15ac7deda4b6eb59d7ae
703275 F20101118_AAAEWA liu_y_Page_044.jp2
12370619786f9de1817dd6963fc7e07b
4729795a89f58a193d3b66de4d8a7aecdc23f535
346166 F20101118_AAAFAS liu_y_Page_167.jp2
06061f1b12e1a57c1975a384f46dccd4
fe30c06ff245699fdc68e2aecac38edbe4b76a62
1051899 F20101118_AAAEVM liu_y_Page_030.jp2
69e2972fe607ea7643b2b8809703a596
d19da057d3f5063b27359bf6b784756dd2f66267
1039509 F20101118_AAAEUY liu_y_Page_016.jp2
844d9e1b2d558fc0db4a90246c4a9be5
0ca485aa9d033c0bdab2a5d3d417673073ff96cb
22954 F20101118_AAAGEJ liu_y_Page_045.QC.jpg
ed7bf6bd23230755f4a74d8e154a3419
211013e2977d87cac9611886a8a67317f6f57e33
27960 F20101118_AAAGDV liu_y_Page_038.QC.jpg
417e95ca2948a8c94feb4a1b20ed3a9a
faa9238f8c9c3543b5cd30fa0f8400f0b7bf9cec
F20101118_AAAFZD liu_y_Page_152.txt
74b8778ad3840c2c59499490b5f4634c
390750392410768bb896789ceb6f42efe4a1cf5e
1666 F20101118_AAAFYP liu_y_Page_138.txt
3502373c9fc7dbbae52c5b381795cbac
a5e9b63dff1d3e61f2771458f196aeaff72cd3d3
1003618 F20101118_AAAEWB liu_y_Page_045.jp2
69d49e72ec8e24662d7850b3f705b6c6
82a89adb12c26bf7f5532e62e5d5e9cf995017ca
729424 F20101118_AAAFAT liu_y_Page_168.jp2
634e8bffdfbf825b56fa4dbe19255ef6
fae6496dd57a16357e6b645ae16f64e997920e76
1051969 F20101118_AAAEVN liu_y_Page_031.jp2
1f3c0daf527c162cf88141a578f9132f
5f310a2798e926c42b1be2059adf2c30b09f3971
828017 F20101118_AAAEUZ liu_y_Page_017.jp2
1258b0c0d53dda391a70c7243932a69d
56da70ea60eb928e39eefa09f7fa3a0b6aa79bee
575487 F20101118_AAAFBH liu_y_Page_182.jp2
134c6a35f225f5154364cb5b64de977d
c2727f23f68682a1e599b9cb7ee3b4f00a45106d
5988 F20101118_AAAGEK liu_y_Page_045thm.jpg
a8ba05bcf447832c8e7a8801f0d38e28
7aef747ebad83e8af321b62443210aa60426bcbc
7538 F20101118_AAAGDW liu_y_Page_038thm.jpg
5abb7ad87e9375a79f1c8c63064071a5
3568b021af774424363bc9634c641fdde7b7849d
1405 F20101118_AAAFZE liu_y_Page_153.txt
48fc8b7d4e48bafb016160d4c173f307
e9b4c305f0c79455f7a9285226fd280e5530b4f3
1364 F20101118_AAAFYQ liu_y_Page_139.txt
dc6ef22bdc65cc0522081942e0af5b82
a19c90f699b26683cc4d9b4a907fb34144550339
935045 F20101118_AAAEWC liu_y_Page_046.jp2
efb53f17f30373b90c557a063e1abee5
24647023ea7bcbe3ef2452034516f797ee55373a
771681 F20101118_AAAFAU liu_y_Page_169.jp2
b41ddda05eeaf290b1346b521e58e099
221fa5bbbb15e0a8cf151c1bd16ad5010a634bbb
855275 F20101118_AAAEVO liu_y_Page_032.jp2
52cf840c33277d3ea7ca0f6dd93358a8
7941717f1228d7b53ad984aa1bfab36871eadad3
619720 F20101118_AAAFBI liu_y_Page_183.jp2
3c97e3fba14ffeb9a1365cfc9d9b6d58
41508d9ff1656d220dbaac2de8037b94d828e736
4079 F20101118_AAAGFA liu_y_Page_053thm.jpg
f9185bdf7df5da2781eaa204c7ea54c3
116b68e60ca7942875a119d84736490257cc985c
22206 F20101118_AAAGEL liu_y_Page_046.QC.jpg
981618327d51603f05d824ea17ceb39e
a91d5e6aaafcdc5107f30e75355b1f03698784f9
24419 F20101118_AAAGDX liu_y_Page_039.QC.jpg
84f7765778067f21d1e5dd3b3d1bf014
bc1915fbcc0cac429d7feaaacfda3b156aefbb62
1098 F20101118_AAAFZF liu_y_Page_154.txt
f2904c010ec211e55295ac7ff23d2e5f
d707eaf21049245d116dd054745179a6d98914a3
1702 F20101118_AAAFYR liu_y_Page_140.txt
d5a281e862d4c3f8a662364e035ea549
649462cf8ad93405f4e8dd821ad7e907436ff86a
93221 F20101118_AAAEWD liu_y_Page_047.jp2
eaf1c5c39354c7fbf9af1f482aa2ce5a
6b204e59daa0335a2dae39efc209e9e295631b6b
732272 F20101118_AAAFAV liu_y_Page_170.jp2
27769878eddbe304254899bd0faace69
187c83ee402ecfc200bde30b7b042493e1eaae65
541218 F20101118_AAAEVP liu_y_Page_033.jp2
82db3ba81e60065f9906b450a64cbc98
05b731d9b8111305a2c82fd7bf6e9034273b13af
829506 F20101118_AAAFBJ liu_y_Page_184.jp2
dc4f5c525aace46d350feab6b3ecd7fb
32277d25de5320eb28bd15fcb2be6aca81d3edd8
10453 F20101118_AAAGFB liu_y_Page_054.QC.jpg
35f69cc967c4cbb3c2d2fae7f2612312
5169a02f6fd94a929744c3ec342f4110f7bc29f9
6469 F20101118_AAAGEM liu_y_Page_046thm.jpg
3ab09baa2c79dff2163262a2d3543886
31a708a5b29cfcde91a1979b0ffa340ee7694121
6922 F20101118_AAAGDY liu_y_Page_039thm.jpg
4f98896a95723da1548764a9dd6e9386
bcc5a19eb0e28ec602231b13a7a74ffc11c2a2f3
1834 F20101118_AAAFZG liu_y_Page_155.txt
fe50794d797c735a20291af15b570a58
9e9122e5aeb581262953749fb8569f87a27bf3e5
F20101118_AAAFYS liu_y_Page_141.txt
399a9b68011cc2c5ad386786b699c2ea
f26481d313008bf8e5b37a7455a291c036029bef
F20101118_AAAEWE liu_y_Page_048.jp2
50a5120eb85e2030a1178a2a16396422
f1d4fa7222fe004afd21467a7704dbffaad4335c
1051968 F20101118_AAAFAW liu_y_Page_171.jp2
b71e437bbba8cf908698be24eabdf159
ab427ea230939a0c110e280bf19412b3381a48bc
833092 F20101118_AAAEVQ liu_y_Page_034.jp2
3eb5f580ddd92399b8bd18ba5da38061
1a50f47cd54ef64515ff97794fcae62f2d1274ba
1051958 F20101118_AAAFBK liu_y_Page_185.jp2
3fa182b085f7a3fdddb25cc424e60d34
332eae6e69c3e3a9c2fb3b1fc424a35121e51bcb
3457 F20101118_AAAGFC liu_y_Page_054thm.jpg
49400cefc04a1cd2c39fddc1de1f637d
3cfdc882243a6fb206cf3811cb9824c8517d0d64
21258 F20101118_AAAGEN liu_y_Page_047.QC.jpg
26210e1d6604761286f957e3d842943b
6ddf888aa01c724afa608020b012ce14932cf578
25892 F20101118_AAAGDZ liu_y_Page_040.QC.jpg
6adacd1ed6286709feb3101e28e548a5
1b70ba0d48fa787ae8e99220c529645e64737295
F20101118_AAAFZH liu_y_Page_156.txt
3d6d40854102759bf07541a8e68efc9e
bb51a66cadb6667d2c8feb4fd86ebf8827169d01
1750 F20101118_AAAFYT liu_y_Page_142.txt
46407ed15ab257250f20edb346572968
40d128bb17da4318591b7cb04ae02dffbb37335e
1051950 F20101118_AAAEWF liu_y_Page_049.jp2
832be41acfccebce6cef928d174e6ced
83f6297ea12cc72080b6a2e2b571022f45c4990e
829018 F20101118_AAAFAX liu_y_Page_172.jp2
bcc290d5e1aa12d40fd85d0e1c6950a4
9b06edfea9d37135fd1be72a54b6889bfa16f732
F20101118_AAAEVR liu_y_Page_035.jp2
d2ae70f01d21d13448db632dc3fbde2c
d3b391e88cefb4b6200dca02873100cc15b6fb5d
1051977 F20101118_AAAFCA liu_y_Page_201.jp2
1272a6d2fab4f661131fae8ba9607a68
a06ed428203fd0ae9b9de1ba96dac4d53cc50f4c
412379 F20101118_AAAFBL liu_y_Page_186.jp2
915ec33b7d9e85e0fb6282251d40636c
54d75c966209e64ec4dd82f290bf0f8908f14a8a
16924 F20101118_AAAGFD liu_y_Page_055.QC.jpg
aa8c2ad4318d524c23c0047688094d3e
db87a0ee41ce211f3864e592aed132d2b1c1151e
6292 F20101118_AAAGEO liu_y_Page_047thm.jpg
57ebcc0a6db77e19bf9623ae70e48bd1
caaa5239937c6c49aa92f1ad601f9b8530039572
1307 F20101118_AAAFZI liu_y_Page_157.txt
7c52d8442b29184e4de4c2267ab429b2
c9cb5852f55d0e9c86f4a264c07087be0d58c216
1786 F20101118_AAAFYU liu_y_Page_143.txt
ec5ad288708b63fec7559dcb8e8ed034
32f8743471ecfea4c2e32cab0aa40e722c3a8f24
1051946 F20101118_AAAEWG liu_y_Page_050.jp2
6c234b3000394368a4ba5c20ba333595
6e374e13935a265e03b86f2f43ba632b2b7365ce
885769 F20101118_AAAFAY liu_y_Page_173.jp2
2f271279f59652344f01985fd1b60b28
f49f0756b20dfb9783d6803e1498eb5e844d29f2
1051974 F20101118_AAAEVS liu_y_Page_036.jp2
1043b7718f1a668922daf0d1d86ded82
fda0300e5d245f7a046c01be83d2b217973c024e
F20101118_AAAFCB liu_y_Page_202.jp2
3dd84de7d4764b95d5c13832f295a64b
0b4034362dc5effe40dbb80e2cb79f45b36b9e2a
1051926 F20101118_AAAFBM liu_y_Page_187.jp2
a03693cbea9a9e04f89274ba04b95b60
3ac1beafce9bd430bc2e94f007421ed6b93d2169
5651 F20101118_AAAGFE liu_y_Page_055thm.jpg
70cc9ef8415c5a48a5612afc228de831
72bb3420710042eabe0b673c96d553ac3f6b2f82
27286 F20101118_AAAGEP liu_y_Page_048.QC.jpg
e3957d8839aedfa53f5fd7a6a287348b
f725db85c614791ee0b02d63a4f37a95ac0f4195
914 F20101118_AAAFZJ liu_y_Page_158.txt
168488a6403693b70a34ca0daecdf61f
fbcbeb45ca75a15922847f09a8955159fb1554e6
1543 F20101118_AAAFYV liu_y_Page_144.txt
c774e433b57fd6f09a0c638fff9ae4df
350c7378626ee75fdb839ce8f02013c088913921
1051925 F20101118_AAAEWH liu_y_Page_051.jp2
963e516656b03e9078e6a596e69e0aec
0c9d0c3a5e6795316d6e98bcea8f06514fbf5b77
F20101118_AAAFAZ liu_y_Page_174.jp2
823b198a96d6c4481fb94abdf328f001
eddc05da9dac5b446240c5e466f7bdd257e261b9
F20101118_AAAEVT liu_y_Page_037.jp2
f6a32f0497062414ee19c9b8c2d04ddc
6a7f2fecc9afe14541b7b696ecfc6288e3105ac5
1051913 F20101118_AAAFCC liu_y_Page_203.jp2
e455d9a20e1b2c56d66e5598a06cad26
3970abf65040054781550655462910c748648a45
961245 F20101118_AAAFBN liu_y_Page_188.jp2
b66e0f03d0ba5a8df6ac4d3218fed129
7ba2c900a44643e078047830caae3af0a4423666
3489 F20101118_AAAGFF liu_y_Page_056.QC.jpg
cb005fc74e4f3c9f0d642bf896b2fe78
51a471897455bd83c133dae71f32a4224a0b8ff9
7211 F20101118_AAAGEQ liu_y_Page_048thm.jpg
e41de2b78525e41ed4345b81731c6468
6e35690c0050acb18e10bf3e6de5c1f27e217f09
1739 F20101118_AAAFZK liu_y_Page_159.txt
7aa791b1c3f35e75d3433f2c8d8cdc6b
b247b093cf81608016eabbcd5934dd4ab0780bc9
3348 F20101118_AAAFYW liu_y_Page_145.txt
45c791f93c37ac208d5e214e11fe2340
604235983aec4c5fb4f7142c3770a23dac0e90b7
666857 F20101118_AAAEWI liu_y_Page_052.jp2
b52a3b419008e2362fd021c8d005c63a
4502f6c092518b2251a600c38423083ebdd5a272
1051938 F20101118_AAAEVU liu_y_Page_038.jp2
c9692536fd36d086ab188398511cf5f0
53107053ae4b5dca07c25f52f1d6cae24a4c3a0f
F20101118_AAAFCD liu_y_Page_204.jp2
64311203dbff443003ed29e95a5eed93
a999a3b1987ee573a8d03ef2a31cbd117951f808
F20101118_AAAFBO liu_y_Page_189.jp2
0932308132832bc7802901460f0ee4f3
581ee2ee416f7e0f662fc0b7848aa540075a2816
1400 F20101118_AAAGFG liu_y_Page_056thm.jpg
ea10243e88f9e9be76ea83bfb1df36d9
3919fc8f4b5a434a1758296411217fbdd48f17b9
24389 F20101118_AAAGER liu_y_Page_049.QC.jpg
1ce54234c65889d0c923dbb5925f93a2
882eaf431a77fdcee31315d8d556f8768ec5d5bd
899 F20101118_AAAFZL liu_y_Page_160.txt
f128ad094b260ee33fb9e3784fa65d7f
89683f36d2fde06388ca67332e8241a69054897a
2673 F20101118_AAAFYX liu_y_Page_146.txt
6c3c9ff99b216ab924da9a1f821da66a
0d68c82cbe3c42e65979d66fef7311d486766bea
498473 F20101118_AAAEWJ liu_y_Page_053.jp2
9c1a3a49c09d87282ce7f9a881f96f17
c412bb4f19b3cc1a988019bb650f4daa5992c81c
F20101118_AAAEVV liu_y_Page_039.jp2
41f65dc3391929d5389224036849255c
3559e114029f5fd2b79bfbc40244352fa1b22823
1051985 F20101118_AAAFCE liu_y_Page_205.jp2
d09b7457b9da640eb367cfe46d1e124d
1b2cf6494902caea7d9d95c2a1289cd1262027e7
F20101118_AAAFBP liu_y_Page_190.jp2
6940b289d55c425dcc5333960a74eb01
eb85d52f7c27adc5659003f9b495e058784a47ad
24762 F20101118_AAAGFH liu_y_Page_057.QC.jpg
b30c2b26680813b7ced51baacb9c1fd5
d2bbd9258a77c6537d83aa2c1b66911cbd2aede8
6719 F20101118_AAAGES liu_y_Page_049thm.jpg
d0f27d08eebaf87780f6ef6053f4793a
43867677119f7f7bd152b1736efe0867e7019073
1462 F20101118_AAAFZM liu_y_Page_161.txt
5f3f5bf1161c67b2f6caf50f3e0d9690
c3cbdf3c694618b2a9e1f95ec9120e1ef8813984
2029 F20101118_AAAFYY liu_y_Page_147.txt
f1719d535eea1c876d1a84fac9033da6
6941641bd24d0b0e353a336431377c8c45c534b7
378277 F20101118_AAAEWK liu_y_Page_054.jp2
ee447548d217a95b36044ad17d59dfd3
eb0cb69c8a1f02fa8b3f97dd5afc079f69f02a3a
1051932 F20101118_AAAEVW liu_y_Page_040.jp2
49e833371e9cc190139870cdab3576e7
66d33759bf8230b4cf78e78ab0418aaa035af49e
1051976 F20101118_AAAFCF liu_y_Page_206.jp2
222a4d26e5b5f9bf13a880e2c2379f9d
e209808ddaa601ca58f7dda37352312e26937261
963062 F20101118_AAAFBQ liu_y_Page_191.jp2
62040d2f31dcc5115c4de2645891003a
a42d5eaf0185ef80b0ea922031fd2026c6d002ce
6831 F20101118_AAAGFI liu_y_Page_057thm.jpg
bac70d0096e34ba68600e59e52e85f32
bbd5bfedca7ec90211d8ae695b8cee95c116370a
26302 F20101118_AAAGET liu_y_Page_050.QC.jpg
1e9f0fd00c6afc30657a1c9fc88d9357
6888926edf1998cc6f2c55cb7db6152b70a48f3e
F20101118_AAAFZN liu_y_Page_162.txt
30d5699a4efc6919712a5fba7d85b54c
1623257b0576a675b1e22c6ed430b95710ca4086
1974 F20101118_AAAFYZ liu_y_Page_148.txt
56553ca48c717e919b961f4b5e043b9d
a05cc260bcaf237c19b6d2c444593810890e7ea8
796216 F20101118_AAAEWL liu_y_Page_055.jp2
f5ec60a9b5d487884071e55dc551e4b3
6d3f48d58a624dcb4c500477838f7dfe217b891b
1051939 F20101118_AAAEVX liu_y_Page_041.jp2
ab49a601499af82552ac52e60be28ba1
eca66ba9028ccca60a62e96a27b771517e93f2e2
1051940 F20101118_AAAFCG liu_y_Page_207.jp2
8f8cf76808f422541544adc2521a0e6e
70303ae6d226b752045b071ac14769b008ec143d
52304 F20101118_AAAFBR liu_y_Page_192.jp2
fd1c0e3b934e5b74d79cd65d13e014de
24d56bd8cef1835f03afa2e8562b678c43329e8f
23554 F20101118_AAAGFJ liu_y_Page_058.QC.jpg
b26dada16c30e2fc52d96037ab47e6af
637ad8c8ad7d9f5ffcfb9812f2cfcd99b23ec5e7
7271 F20101118_AAAGEU liu_y_Page_050thm.jpg
a3fe6ca6c946b56e7f5ab9ca0c5b297a
26c429025d7746edb6065c807ef2223085737c15
1318 F20101118_AAAFZO liu_y_Page_163.txt
da7f9e7454fa49d3dd53fe2bbc3f5292
9eff1ff9860a5d9e4e56be7810c726acf91f7ada
36707 F20101118_AAAEWM liu_y_Page_056.jp2
15dbb197ac0976002f89c919453e95b4
8182dd211ea7556d070a09dc61580cadc87d2654
1023844 F20101118_AAAEVY liu_y_Page_042.jp2
2585e6e12992d0fbab62953f520a0768
8b0e7f2d269b8c4beb7e55502e781ecc23c86b04
1051943 F20101118_AAAFCH liu_y_Page_208.jp2
ff28f3eb67dde4cb39883b8a6a4ec956
de6974e2ad1ef3a0c5a8c127c1b8d34e4b6328d9
759636 F20101118_AAAEXA liu_y_Page_070.jp2
a65b810dab12a8d7d92e2d2fb961be8f
124eeecdc19543f04a813a71d08207b2d4de026d
712668 F20101118_AAAFBS liu_y_Page_193.jp2
a62376b3bec0c950b494cc818f279dbc
a079f421a87c3e802c1f1cc661ba396a52deb85d
27118 F20101118_AAAGEV liu_y_Page_051.QC.jpg
1a103cfbfe58b491f79d73e3e985b31f
5beb76d60d05a9293c8ca8ddc31c88d4ebfbc6f3
1306 F20101118_AAAFZP liu_y_Page_164.txt
c55d8782b4163431ea321f4c832dcb34
ccf5da5646befd0b28e043f4af26a08b09985729
F20101118_AAAEWN liu_y_Page_057.jp2
544b0cb0d9f416e78deef92994d014d8
43cd067683292fded29339b68963914887f4652f
474501 F20101118_AAAEVZ liu_y_Page_043.jp2
0167f48df2f369d28b530d3903dd7732
cbd0fc5ae2c1a66ee7ef68de25c292f1d1609b40
1051973 F20101118_AAAEXB liu_y_Page_071.jp2
4f9c99fb16bfd4470813b87fa90d67cb
2466a7cdc7e433021c5f0bfb35b47d8e58f667c6
538766 F20101118_AAAFBT liu_y_Page_194.jp2
422178e95223fdadab52ba724cedcdde
696aefaec8a79efc20af2b1385cf9579d0e3a7f4
6449 F20101118_AAAGFK liu_y_Page_058thm.jpg
d1e71a6e33f9cdd54394f596addc0021
210f045ff1716a96fe5875462c601b372348273a
7460 F20101118_AAAGEW liu_y_Page_051thm.jpg
6b3c56cadddcfeb68db57e32667c39e9
936ee06692835c8df6b8474b4c05fc3460f47aee
1474 F20101118_AAAFZQ liu_y_Page_165.txt
49397f400d14e54d62acb584b9ee23fd
6f46d0095e4523166ab8c3e6101d1c572f62b932
F20101118_AAAEWO liu_y_Page_058.jp2
577023e27fb8075132ce6ebdd41e4976
b161bc87901a62bfcabd4ee3091fb6c2cdcc098b
F20101118_AAAFCI liu_y_Page_209.jp2
38cc1f8cde245b9030793c0a12894587
b0f9c1740bda78e0c9e6a5b5833a1d5cb1a769b7
F20101118_AAAEXC liu_y_Page_072.jp2
ee8042bbe15656b1b1903ffb3e122b7b
f47e64d8b92ae705ebbe1d7a34084bbfd3404c7c
745882 F20101118_AAAFBU liu_y_Page_195.jp2
b65f309956b56cf937028699bdb67e76
82355876550a8402bb29a03ba16c00a02f9d2bfb
26482 F20101118_AAAGGA liu_y_Page_067.QC.jpg
ae6db7a09107b04aa7915dddfec60921
2cffb00b46e10df4715bb512e9fbe7cdb8dd0458
27105 F20101118_AAAGFL liu_y_Page_059.QC.jpg
1f4c498199a12dedea550ded416b7ac4
9e0208a7c8e24e39b3e6082f5c053dcabaaaab06
16241 F20101118_AAAGEX liu_y_Page_052.QC.jpg
d36dd1b9d03144bff18ff1e46dba49de
bc68303dfa6f2853c8c328fb748906775142628a
2418 F20101118_AAAFZR liu_y_Page_166.txt
de175b2f2513960581b1dbbfad3491c8
7aa7348ac9d73322cc062b78ec53d33d7ca7b160
F20101118_AAAEWP liu_y_Page_059.jp2
62263472ee79645979ce6e68eee05721
7ed44c9504dea51733b319dc6c7d0052977db27f
1051861 F20101118_AAAFCJ liu_y_Page_210.jp2
dcdd290ec445603b647ab0dae47222ac
4964cf788011d0b3be40a064379c47f089e1b965
1051888 F20101118_AAAEXD liu_y_Page_073.jp2
47f0bd9554cc8ddc1b1cbafc1c11f9b3
a84f47dbce929528e281b15882e69de53b38ead8
561207 F20101118_AAAFBV liu_y_Page_196.jp2
f7b87b08694c3bbe1bf1f02fdcfd700d
64cebcce44ae91bcaf27eb4b89d5696f74f9fa3b
6950 F20101118_AAAGGB liu_y_Page_067thm.jpg
eb6939fee9ea39e9e51a91f123af5175
95978d77c78f74929254420d7f465337ebb886d4
6787 F20101118_AAAGFM liu_y_Page_059thm.jpg
3227fabcb49ca40ec63d77b1d8e1d582
f8c67b24e1871bcf09f9a644a17b943ff63d25e5
4807 F20101118_AAAGEY liu_y_Page_052thm.jpg
354282cc44d19f6d4b841fee30e0de47
af508feac445a3494264314d0d13e46a04d66b0e
667 F20101118_AAAFZS liu_y_Page_167.txt
14764fd6c5d5a110d25b215f0228211d
1dc8106cfdab00e0c75b3c18e8c1dd4d252bb3f5
727017 F20101118_AAAEWQ liu_y_Page_060.jp2
978547a2ddd71d9195ca7be57f38ff62
4e5510a1bba74c0cf28b663569241b3449014793
F20101118_AAAFCK liu_y_Page_211.jp2
54a4ea518e3003cca43d88e390b802c2
5d92de28f90eee334d974623fda777ff1fc3d30b
66485 F20101118_AAAEXE liu_y_Page_074.jp2
f274ea7bd8ee9c21b434739f7576c9de
1266f520487bc4ba8a6c082b7d8964aad620502c
591042 F20101118_AAAFBW liu_y_Page_197.jp2
0e295852d3b2c76c5d87f8c67177191f
9d3b98b9415badeb0b482f9310cd644c4910f5ec
22832 F20101118_AAAGGC liu_y_Page_068.QC.jpg
dde4561589615dd6a21c23a15bdb881f
fabc0c70d9b880e50ace514bf7462045fcac2c3f
11814 F20101118_AAAGFN liu_y_Page_060.QC.jpg
4cec382eae31eb39af03ba26dc211335
29d51596d39ca46bbe08098f2792eb6f3f7bbfc6
12873 F20101118_AAAGEZ liu_y_Page_053.QC.jpg
69e75f18279e4b26d7e36aa3d88116a3
9ff6591b87011e8a5a99629208c9ed3beda7dd57
1485 F20101118_AAAFZT liu_y_Page_168.txt
ff4a32432515d41da72607f122ccfbd4
543c4fcb2d0bb6810384c72be47a969fba9b953b
969406 F20101118_AAAEWR liu_y_Page_061.jp2
8e316948dd568ae34494eb31f01e20e7
a5126234c6651bb789f015ff1fcbe1cd379ddfae
25271604 F20101118_AAAFDA liu_y_Page_009.tif
444f4d082e3682a489b344139b40ad65
7a9f89b070e0afabc13e203e7ea189e6635455fc
1051954 F20101118_AAAFCL liu_y_Page_212.jp2
7190ca0202f4b39555fc32fa4f2b6ac4
6c60df031919b94d7e09a976ddeb613d68d36cb5
F20101118_AAAEXF liu_y_Page_075.jp2
156b992ae59f168bf064f9a7c2ef9368
d06388c511a54fbaa4efda34afa9cddb5b8139b3
64649 F20101118_AAAFBX liu_y_Page_198.jp2
47bd8366776c7a9a9d2e8ea11cbf880e
0097fd62a04f731f382d64904381ef51459f9810
6474 F20101118_AAAGGD liu_y_Page_068thm.jpg
e90c2896c364cd6e26084bd8ca98be6f
8cf3d0f2e52e5388ae518f11b05a1f1426785895
3435 F20101118_AAAGFO liu_y_Page_060thm.jpg
c793b0a85e42a1d22a5fa0b6f327489f
89182a16bb4b09c0674b2286fe3c73edac16e7e0
1695 F20101118_AAAFZU liu_y_Page_169.txt
c24ca4e9d74c04108c8591ad595f958f
325e77ea634b9c69e7dc1eeef47106acc6fbfe3b
353299 F20101118_AAAEWS liu_y_Page_062.jp2
f8ad19f43cfa5a2ef41f1f87b65183f8
1baca85fd6de094153918c37e5de060f14636148
F20101118_AAAFDB liu_y_Page_010.tif
21d7d6d41433139d617ad45be74d592e
b29ce8e794f718434563a5a436f50e5a04787835
1051967 F20101118_AAAFCM liu_y_Page_213.jp2
24ef8d877854bc592a6601df3c9e49bc
d4d1622242a3ee00eae5fb122e50c8d0d1b99224
793102 F20101118_AAAEXG liu_y_Page_076.jp2
f60e2a3644f9a49008eeaeb45fed2ffc
639c19cd8373cfd93707e3587c3658eb7f1407da
F20101118_AAAFBY liu_y_Page_199.jp2
d2657e75c23e9d55cd836514e899eedd
b4b2e41f855282162628824fd51327ce8fc2424f
19588 F20101118_AAAGGE liu_y_Page_069.QC.jpg
99043dba77c8db28557a419af857027f
05f68ca84c9d6c7500b79cca4a555dcd94194a20
14517 F20101118_AAAGFP liu_y_Page_061.QC.jpg
07c2473b5ff6a8f2bd9419fa2e7b4836
c7a8b0f9deaeb04ddde3647c14381dd65596def2
1687 F20101118_AAAFZV liu_y_Page_170.txt
c3d833ef4adbf912ab280a234d33cecd
f3b9afdae155744b74421139acc16b352ab3b3a8
332151 F20101118_AAAEWT liu_y_Page_063.jp2
690b86a81ce6e1f2aa21f4445f6e3944
2f9fb941061259dc1a14c0d311a16a958d382757
F20101118_AAAFDC liu_y_Page_011.tif
def068e3ecf3b589ecb244d3bce6ad1c
13923d78e455cea69195e406f33b694b258b9937
F20101118_AAAFCN liu_y_Page_214.jp2
8b8f4785b9e42023ebb62819dae064b6
ee7a1fc5d7947dcbfe505cce7eaaac5e5911e536
959542 F20101118_AAAEXH liu_y_Page_077.jp2
034c02fb8881fb87dbc4be73f6adec61
f657147fb53d24304478087883bf85895f018fb4
F20101118_AAAFBZ liu_y_Page_200.jp2
297e7e0f6446faa6c51d0ec2f2c6723c
ce608b88e81568205d6d6f98a05ae67073656dc4
5755 F20101118_AAAGGF liu_y_Page_069thm.jpg
55f69fa4bd00be770ac3519c94b4e630
3992a72ed5fe65818b1f7d6d569983dff0843067
4385 F20101118_AAAGFQ liu_y_Page_061thm.jpg
fadda1ed41473a22d80740667f0cf14f
ea646524301622405ab17e777a6044ad35a59a21
1503 F20101118_AAAFZW liu_y_Page_171.txt
5f61e660241161047dc671b8a49e2020
fb95a3ce850f700d5624a2b7b487f17113326d84
1038962 F20101118_AAAEWU liu_y_Page_064.jp2
4aabb801d45f28113ff72fecba19ea34
a829b6d6e20f03b65a2d8dbdcab9c1c190075db4
F20101118_AAAFDD liu_y_Page_012.tif
5db0dfca69e1df18cf5c95cc491d7357
71863081b9cf142a31be07b757e0b4773b538d08
F20101118_AAAFCO liu_y_Page_215.jp2
d8f60f02033af2f32476d5037094963d
cffdbe77e08d8c5f21d77cc9902d5a99c3dc46cd
954755 F20101118_AAAEXI liu_y_Page_078.jp2
f492e5ec0114d39661fa168e35b44bfc
bd57b99e384c361e80a5152e67e2f7d88d136989
18763 F20101118_AAAGGG liu_y_Page_070.QC.jpg
3fafd55d522f97f12a32ef5fae192851
b49aef81497442b76d620a19cfbffdc1859d3b27
10561 F20101118_AAAGFR liu_y_Page_062.QC.jpg
584d8edba9a94c51f81483a3f7923d45
4b249e5b59fc3ee0251b256212b1c5dd69759268
1683 F20101118_AAAFZX liu_y_Page_172.txt
2b38f84bf64fd8aff3b7e5e858885f74
f88b12142be8f7eae1c2b39db12e972d8ee58174
F20101118_AAAEWV liu_y_Page_065.jp2
d9c85e467b451dcc32b7a38249c1eb7c
601f5986bd776abd29c2d5ecbe405aee24e8ce49
F20101118_AAAFDE liu_y_Page_013.tif
57ee8abe71bf1f877511d1bbe37daf4a
63742bf48a4d12141685496a4a45961633a84c94
1051827 F20101118_AAAFCP liu_y_Page_216.jp2
dd324cda86e7f3c1ea4733ae6724225e
93e303a2a4d1aa7738eb302292bc8fa983cb320b
F20101118_AAAEXJ liu_y_Page_079.jp2
90723988c8e57791cdb3fa92a2eb648d
09de8b95401a4288739cbe461ae4344430ab0926
5526 F20101118_AAAGGH liu_y_Page_070thm.jpg
6e2a4ceeac9a0ba4d7634d13fb10e66c
2fe8cdd101585659c80b49c05fe10d042a5a4d48
3244 F20101118_AAAGFS liu_y_Page_062thm.jpg
9b4bbabd659dc7abf4f0798295313474
d6136b79b650b11047e6b6a0a94a8dbfd01cae59
1920 F20101118_AAAFZY liu_y_Page_173.txt
b042393c8750ead827dc2e142209429f
96b8098c8a1829ab4ebbe63a55171c8fdb1a8905
1051944 F20101118_AAAEWW liu_y_Page_066.jp2
5fa252cb765f3f38538e1add903971cf
7f2f60301b95682b5e486029e6b661675cbf36c6
F20101118_AAAFDF liu_y_Page_014.tif
ab801506d7c05d9dc07b4752d9885c91
db07acc3e8f7a7c7cc1c92991c512b519a973882
531383 F20101118_AAAFCQ liu_y_Page_217.jp2
4061bb81a577a3d282b3312d66fc3202
4d9b6216569fcf59b208763a4d0b5f8736674a9a
902102 F20101118_AAAEXK liu_y_Page_080.jp2
57a86176466a7a2ea48609b12adecd36
f436c6ffe431e440a5da61ea85031a0aa86daa15
24684 F20101118_AAAGGI liu_y_Page_071.QC.jpg
ccfdb0b72e53b4f312c848d40f4d5258
2f2aedbbed1bd9c1b8fd4d0e4999d20bf539c8a0
10968 F20101118_AAAGFT liu_y_Page_063.QC.jpg
08ba5ef896f2f1d28466eaa8ab08fe90
7e481eb3def529bb8425f1e6a4a3136043edb888
2773 F20101118_AAAFZZ liu_y_Page_174.txt
64259fb01d1899405478ea3b6ae792f7
c02b79d041a8253c1c503e3427b4db65287cf318
1051983 F20101118_AAAEWX liu_y_Page_067.jp2
729f47f2da488801bee3ae243b511f53
f87efc975f1a7e62c9f153127e05eb960bb7e40f
F20101118_AAAFDG liu_y_Page_015.tif
ab333db7bb7e69f5066ad6a4af727e39
c4f24de557dc9b173cca40d81729776b46950ca2
3552 F20101118_AAAFCR liu_y_Page_003a.jp2
17431b3cf496028b592635f7a3dd6641
608c968231b04e7e20442afe54bdb7dd9d32c2e3
F20101118_AAAEXL liu_y_Page_081.jp2
faa97f6fb8afe86aa17d29416663e6e5
0e38f42a74022cf3f370446ddb08f61a3db4bfd1
7021 F20101118_AAAGGJ liu_y_Page_071thm.jpg
5944bccc45968637b3e0d3a26a67f8cb
d430ea50ee6479f27fabb4332e791966c07f4083
3453 F20101118_AAAGFU liu_y_Page_063thm.jpg
02ca0c4c4dad6518e61623ca60079a05
523c610fadaf4abc3e2d3289b6b4ff53c2eb60ed
989332 F20101118_AAAEWY liu_y_Page_068.jp2
cdd3c631bc2b7c91a748b5f8bf2823d4
e22b86d0c7d128390dba62e7dee6b73572de6909
F20101118_AAAFDH liu_y_Page_016.tif
6daf00caa83bb4c4fd7cb16f5a6c14b5
3c91df5bbb635c63e46f487ba7dfe67f1952f405
390941 F20101118_AAAEYA liu_y_Page_096.jp2
b9babd947b9cf09f05ce9ed2f71a3c5c
e3ff1a512b39f883b6c14ed5f8ac7d4935418454
F20101118_AAAFCS liu_y_Page_001.tif
5052dce28ee6748cbd4a160dbe58131d
53a98d5114b89cc0be2c13444abf130f47b2efc6
337643 F20101118_AAAEXM liu_y_Page_082.jp2
e404c1551d8593cf7ce869cc31517ac2
c7c8c0dc3fe5e5cd58f73693892886eb95c77d56
21105 F20101118_AAAGGK liu_y_Page_072.QC.jpg
800ad0fcb01f4bcc0dafbb8003334333
3f91ecc4bb6c902266b7f1a35dd0cf7416324ecb
20403 F20101118_AAAGFV liu_y_Page_064.QC.jpg
6b6c1ab47ef597ba64e0e49ac9706820
cd16fd8e5d400edec6432a3cb0e88f7241a4a04a
902673 F20101118_AAAEWZ liu_y_Page_069.jp2
659e3edce765b758fe2ec37a518ec202
fb8395ac3a20e0096baba3b2feccb8a94edf21da
F20101118_AAAFDI liu_y_Page_017.tif
5bcfd0d10d8289c5661f6096af57fca9
30f62e9bc95bd73f3d4a005aaeafd92fe8b37af2
833717 F20101118_AAAEYB liu_y_Page_097.jp2
cb696afd8f7f3b7368113acbb6e21427
dfd646b315a8084fa33270d7824a4478e45620bf
F20101118_AAAFCT liu_y_Page_002.tif
adce1675302a99aaf235cb1363d99aa3
d4191bed304d41a8419f6ce06041a5bd3c10dea6
750348 F20101118_AAAEXN liu_y_Page_083.jp2
828b5e811d27a7038badf3b8fdfa1724
0b531e32de71550564840839e63b01824a59bbe7
5740 F20101118_AAAGFW liu_y_Page_064thm.jpg
0755d4d40ed72bb0e40aabccf8a413b5
0de80140043b71e09af3318d256c1d7a2383e48b
1016152 F20101118_AAAEYC liu_y_Page_098.jp2
f3e8714a7ef38372d14bf7ca2481a658
1510666be121f95c50983f534d4c1f9ec141e191
F20101118_AAAFCU liu_y_Page_003.tif
dbbe606d249659068564c1bf37e625d2
11158d77390c04b31d67fdc1edc59b7ae3b3ef95
F20101118_AAAEXO liu_y_Page_084.jp2
c46a8563eb3de79b68f0f6f5760b9b44
6e26793e815e1778be42ad1c1fec01dd112ca3e3
20275 F20101118_AAAGHA liu_y_Page_080.QC.jpg
5bf218e6e58656f3a71b51477a417e3d
eb134167136197c6f516d113ef2ee121ffcc7e0d
6421 F20101118_AAAGGL liu_y_Page_072thm.jpg
91e80a958d0aa4d0037e22911ba02d87
db36df544b838c7bb846a20a1efd712828ef482e
7169 F20101118_AAAGFX liu_y_Page_065thm.jpg
88e58500ca1da48f9edd4c2775153163
d035602d0d4eda8a5545d08f72e744f54920d925
F20101118_AAAFDJ liu_y_Page_018.tif
823ccbfe608840356fbf68dc762f9120
8d33c595ca1fdcfef50d0068a60087ff3899dce2
938979 F20101118_AAAEYD liu_y_Page_099.jp2
bba8a1d14d571d814535130e65a2f015
22ef8738adf57a11b92ea609ac381c04d9d35b8b
F20101118_AAAFCV liu_y_Page_004.tif
830a0ba1a845c72aec0944a48568f46b
65185c877511fd96b8d008df01e4770d003ec1c7
F20101118_AAAEXP liu_y_Page_085.jp2
e0edce54b9b4aac165e1f19df6686ee2
cfa7b0c5961344bb516fc7c09f3a02a2f0b8faca
6147 F20101118_AAAGHB liu_y_Page_080thm.jpg
305eec15c43c3ad090ee036e8749a80b
20b7ca4f1ed7d24b4feea4499c9bb4cbe2301f3d
19142 F20101118_AAAGGM liu_y_Page_073.QC.jpg
798517e9d77115bf2340f2a78f94d955
cd697666ec5b87079d1057dd36249d0c97af869f
24080 F20101118_AAAGFY liu_y_Page_066.QC.jpg
f0f80ab97b4ddf48287f6d201680b3b6
83261947c2c66100196d75d99853409b2e662187
F20101118_AAAFDK liu_y_Page_019.tif
e0821eb01de7f465e5eb048ea3a0e964
37664547ca2129b357073510cb98a84865396ac6
939246 F20101118_AAAEYE liu_y_Page_100.jp2
9d588c91899ef223492b40a52e052217
555e8c634db33844568b0665af41039a90f03b75
F20101118_AAAFCW liu_y_Page_005.tif
97a340fb4089c6de7874b87c4df413f4
322da270794e1d5e8d259ba65215439acd62462a
749453 F20101118_AAAEXQ liu_y_Page_086.jp2
30adfdd42f58588bd5cd91070d6baf4d
0fef3587f630a50292b31866d60e27d7738f528c
24457 F20101118_AAAGHC liu_y_Page_081.QC.jpg
e686724cc8d09a095102d637ccf1fa7e
dcd2ef401cf0bb19e22d2309cacc01209e5cd01d
5582 F20101118_AAAGGN liu_y_Page_073thm.jpg
a8cf1a7626cc1431e5752bb72c1941dc
70275672baca0166d2d0d497ec8d231156c87eec
6931 F20101118_AAAGFZ liu_y_Page_066thm.jpg
1a3899dfe55742ebdf13e82ce60e1233
007113fea70b3bc5f17b2e52f9a91421c5fab3ad
F20101118_AAAFDL liu_y_Page_020.tif
9563c22f2be72c76a87a95f67bbc8dcf
ce5727f5171e07e544efc828252c733d3453a994
915075 F20101118_AAAEYF liu_y_Page_101.jp2
ba514a109419a25fa3e8aae654720fb8
46f2b121d258c30ad707279046322b73d2e4cd6f
F20101118_AAAFCX liu_y_Page_006.tif
90a7b0e1c6541c9d1d9e10de71dbc9c8
315623da93eb84e06cc622e15563803e3c92f8cd
875258 F20101118_AAAEXR liu_y_Page_087.jp2
b01bec2a16d2d2fcfb0bcbf1cbf50960
8e969097c90d14ed1d2a46d3a3ab2e1f7985110b
F20101118_AAAFEA liu_y_Page_035.tif
d058f4ff6197637dde38d9e1699aab5d
27cdcd9a0419382e89244d85da06ae2c7bd19403
6744 F20101118_AAAGHD liu_y_Page_081thm.jpg
460f1960c9e8b6c0c98af8ffa537d60d
7e78c5f52ca1bbbb965507c9710c230a078cb1b5
4017 F20101118_AAAGGO liu_y_Page_074.QC.jpg
a6143043f020b1b00da6525727691f28
5aa8b241a5ad73ef6b32aa89faa41af076e4ad23
F20101118_AAAFDM liu_y_Page_021.tif
7748bf89018c501c5ced4ead681f25b0
f2c779575a0690183dea2e1567beae00d3f2e737
978952 F20101118_AAAEYG liu_y_Page_102.jp2
c4674625ef71518cfbe8d27ef3c14548
6c486b18de5eefc7e4af714d756ccc2dc54d695e
F20101118_AAAFCY liu_y_Page_007.tif
270ee1cb59fb826e009e04ad69650ba9
b15062ea3c76e202977be34d6a1e29113a329cb4
1051981 F20101118_AAAEXS liu_y_Page_088.jp2
8adacb7be5ebc7593aa6627ed45caecb
7d205dbab4ede398d14d71e955d7af055dda6b36
F20101118_AAAFEB liu_y_Page_036.tif
7fb4a11324e533b22cedad701f65b82c
e6415d949d4e1f90451455220a257cce401c142d
8869 F20101118_AAAGHE liu_y_Page_082.QC.jpg
0554204f04615a999f978f113b00cc10
6f110f9b181719073426d956f4a32ca35f34d22d
1532 F20101118_AAAGGP liu_y_Page_074thm.jpg
1c5c4905b3da1dc52e2417d7bcfaef28
ca228f9f937608d16976a91399ca76d81b888dc1
F20101118_AAAFDN liu_y_Page_022.tif
59b045b440e98e1b81c2bb6045d22102
033291b4470273d9c905819710462aa28b6df17e
F20101118_AAAEYH liu_y_Page_103.jp2
8441dd7f632bc9693a92d1c10d552783
c8f322839f4b850b8c702c31746de8b91c9c38ba
F20101118_AAAFCZ liu_y_Page_008.tif
cdf9208ac9b599d37087502c22de5097
8c83833eabea8537807d1708b9f6ff3170392af2
F20101118_AAAEXT liu_y_Page_089.jp2
4ad2aadc775c1dc2af40031bca9d2513
8b1b2a791260c05a2dd26198921669f697afaf87
F20101118_AAAFEC liu_y_Page_037.tif
1d6293a3be6e59d1e572250849406a7b
e884a2a89fcc75147fcfe7b13d040788d863537b
3088 F20101118_AAAGHF liu_y_Page_082thm.jpg
c017cddac5b1bf39d03008ce45ca3613
bc01dc46f4e0ee631efa75cea937e964c9aaa0d3
23286 F20101118_AAAGGQ liu_y_Page_075.QC.jpg
f9a2b8e9e6035b4f9b6d9c45c19fc473
cc8d78d1a4f721f326c6b4a7469f52364864d631
F20101118_AAAFDO liu_y_Page_023.tif
f0ba5acdb440b8b07f1ef4e8bf6ecc66
59429f5b163c158e5cdeb7a721e95d9a58cebc80
F20101118_AAAEYI liu_y_Page_104.jp2
10d55bc008f65cd0b0322d4c792b975b
d799cf0a9e50f03f3d48f5d8b2dc6deb79363e25
883433 F20101118_AAAEXU liu_y_Page_090.jp2
acd864b1b5002b46161734015b3bb2fa
885fdae336f0a83b0e933ca5b4dedea663dada7c
F20101118_AAAFED liu_y_Page_038.tif
8d908083e7151ababbc2ef3c63c35563
99c19a3349625564dc3df5f141bd027b6c9618e5
11245 F20101118_AAAGHG liu_y_Page_083.QC.jpg
a125159c632c6f9dc3bd7cc3c536794b
3fe63a635587087c9daa117bdf28b7f9f63ca3fe
6543 F20101118_AAAGGR liu_y_Page_075thm.jpg
cff2b397e8cfee513610da5065a20e3f
aef78d5e93ca8063b6bea559154db814cc505ad4
F20101118_AAAFDP liu_y_Page_024.tif
f6f152db6eddaa6a1a1e20c80d0d3be4
4ce8dab2b5b9968c5a45a5799e8d0da0d5a7b3d4
388129 F20101118_AAAEYJ liu_y_Page_105.jp2
db2db3b70ea10a508f60b58cac4fc907
6c626886a35b2c886ecab399c9eac5d8fdfefb6d
831281 F20101118_AAAEXV liu_y_Page_091.jp2
e6d227526fa23bf05ef42ff973e03406
7337bdd4cd0ad0004d5f6ecf932becce978d5169
F20101118_AAAFEE liu_y_Page_039.tif
86fb31e0f08c0c0af34041e0ae0a61a7
a3e650f89ddbe724e35580d0671159b892b49148
3849 F20101118_AAAGHH liu_y_Page_083thm.jpg
5a5c84eb94f395c55158d1d9d083a3cd
5875fbe0b144c0549158bc3844de7e64a1601440
18335 F20101118_AAAGGS liu_y_Page_076.QC.jpg
c9221c083d8e6904a1eee2866a2d69b1
bea246d477051e0c3bb474d7fa51389d381620f7
F20101118_AAAFDQ liu_y_Page_025.tif
7b5158438afc03e1d39c0579fdf42931
64ae13ee6bbf1fdb022a6c57b325d357d71cd26e
1042620 F20101118_AAAEYK liu_y_Page_106.jp2
f25cc37eb40c33dc28f620876add069c
65d5a0eb98c59029c0b80715ac4bc1f1553ed5a2
783092 F20101118_AAAEXW liu_y_Page_092.jp2
afb5f93d8aebf4e4f142df74b9195f9d
aa6e1fb8c3d1fa779bb6cd731917ed3381436b3e
F20101118_AAAFEF liu_y_Page_040.tif
2a585118cbd5b0617d0b6b6ebd95cfbe
d28a3307197197381c3709e4e05a5ace092912df
28860 F20101118_AAAGHI liu_y_Page_084.QC.jpg
4b00de115a9c24dbdcfe53b947da63e0
d9b9827ca2469e9d88f2f94291790a5d65d61012
F20101118_AAAGGT liu_y_Page_076thm.jpg
9f0c9d89fff09d1d6ba4534092671ecc
5f8b440621c2f716b3110d9bf5b936e46474aadf
1053954 F20101118_AAAFDR liu_y_Page_026.tif
4a62a40cd0bf5bc3d7efdb7c90488adb
312f388ef92291687d1113f16d8d2068fc943fa4
488680 F20101118_AAAEYL liu_y_Page_107.jp2
81ad4b7c4350e10a7fa16c150a197e5c
98b537587f7f6efa80d3fab5eca84b5c3e518a0f
649284 F20101118_AAAEXX liu_y_Page_093.jp2
08fe76eb24b2c12ed89689db981c9735
f6d2350c547e717b45d7807d4dab2a807ea3677d
F20101118_AAAFEG liu_y_Page_041.tif
05e5ad18aefe66a6d1b52d2c4135d6dc
2627f1d06c6e66ac3a5d86778d1f3e001f2345d0
7633 F20101118_AAAGHJ liu_y_Page_084thm.jpg
6fc473b5aedc697103ced0b9a291085b
40fc0ca03071814774094196f71b409153b95e10
16981 F20101118_AAAGGU liu_y_Page_077.QC.jpg
b25bb6558e65285d48d0f22b1c534877
1c1a2fb82dbec6be3e3ec367ecbae28f4589b6b7
F20101118_AAAFDS liu_y_Page_027.tif
35d80f2b0bbccc17539f3b45e955c971
aa4926601b7486bd86210498295699bfdf6df382
623541 F20101118_AAAEYM liu_y_Page_108.jp2
cc8222094d4151313495316b44e1bad3
82230f6f69f64d34c95a4035c0577db5fc8c7587
1051962 F20101118_AAAEXY liu_y_Page_094.jp2
5dbf0c80d457435a89a1d1b829c58d3e
0aedac2b09d26723a270051e8c548e4f17a81a30
F20101118_AAAFEH liu_y_Page_042.tif
1a8d48d66b82f0b687ad6e486fd047ab
68af3541ff042ceee4fe6103fe035dfece18f146
566444 F20101118_AAAEZA liu_y_Page_123.jp2
d0d822e4b720073f362bf2cb0c764e18
47f2442d9b125da5d566dbf647e78c82ce51b3b4
26136 F20101118_AAAGHK liu_y_Page_085.QC.jpg
ea899579eb2be649a1b442f35058447e
826f2d8ee3c5c6893767bef3e10767371e7e95da
4900 F20101118_AAAGGV liu_y_Page_077thm.jpg
d095f509417082d247f3e56654be435a
ffffc5f62d347baccc7a43addefdee864a93fc3e
F20101118_AAAFDT liu_y_Page_028.tif
737835e1a7b113b89995bfd531fd2cd9
74d8f650e237d2e087b065f4a42b39e393299381
181761 F20101118_AAAEYN liu_y_Page_109.jp2
b60d5d4c8a6a9e7217f1db0c0c17834c
3933e434c45b1662127cba9e41849ecb85fa8f3f
626779 F20101118_AAAEXZ liu_y_Page_095.jp2
97962c2a3b42b34f91d9b6cb0e5d2b0d
242289bcdf211929a33e3401f68340d102267183
F20101118_AAAFEI liu_y_Page_043.tif
5c9dcd80e9ad5571ddaa2dbd24576e72
1a1b62f74149f30aad1c4333aab2278825a7de8d
927074 F20101118_AAAEZB liu_y_Page_124.jp2
01abd888ddadb0b74b7b8c9d2f360b55
d88ab71e953ad367373d52b2746d974029a34cfb
6895 F20101118_AAAGHL liu_y_Page_085thm.jpg
139bf3105dcea64250fb9b435f583067
d898fe7837024543f5ddc2c2b5a9e202b314220f
20349 F20101118_AAAGGW liu_y_Page_078.QC.jpg
9ecade57b9809b5440c042d95b57c65f
5adb92556439b5069b7bb9218901b416645879ae
F20101118_AAAFDU liu_y_Page_029.tif
13528661dcd4f574b64151936ab79648
ae5ea83134663284e4ab9dffa704e98f7de992af
906936 F20101118_AAAEYO liu_y_Page_110.jp2
60daee8de218b7c58204b0ade62c0674
69b5c4c152975accfa5417ad2507fdcaedb062dc
F20101118_AAAFEJ liu_y_Page_044.tif
4f502be54d82b423da6d2a3303e4c61e
81058e0888ea5fbc8e627c53d24d8a7dee2266be
962349 F20101118_AAAEZC liu_y_Page_125.jp2
a2bd0c4525b42464c00dc235082a8784
dd8c72335e37dd1bd222863ad167a4d83a0ffb40
15707 F20101118_AAAGIA liu_y_Page_093.QC.jpg
108789c2421650b04a0a6d460c95b149
321471a68e2189a0b109f4e6dd63a80837928252
5942 F20101118_AAAGGX liu_y_Page_078thm.jpg
ba133145dffbd157464efb146f028928
06b887ae154f6e9f83e7f9a1367c28efe1f95c70
F20101118_AAAFDV liu_y_Page_030.tif
3fb23c37676ed2995cd3d9908895a1fd
0543a3ef154d367fce90da0fa96b257fee89f070
932451 F20101118_AAAEYP liu_y_Page_111.jp2
3cf9cceaecfcf2dc2ef87b67f9d7f7d7
8dd3e80bddfe7bde490f3b106e7cef574f823dae
F20101118_AAAEZD liu_y_Page_126.jp2
cf6fbc5f54df92ca1d0d0d88ab7ae8ec
bbf09b9418cf3c663c48dea00fe2e7f28a0ca0da
4439 F20101118_AAAGIB liu_y_Page_093thm.jpg
8b107c4ae8eaa63cdb6c33fa5a571958
01490ca79071b595f78699d06b47449f73ff265b
15370 F20101118_AAAGHM liu_y_Page_086.QC.jpg
709e92e9df2cd94ba4fc34a82642b5d7
c063fb85241d049046b99236dff9b51321d0ee2b
19784 F20101118_AAAGGY liu_y_Page_079.QC.jpg
64b3816a3d718576101b7a8f606486ad
eef65315f7b61ac647e90ce4ebc9174d8dd88782
F20101118_AAAFDW liu_y_Page_031.tif
55c33563244e8ad5dca625a89b8e562d
dafb90e67f7cc9c51b399ea901f7a35c358a9e65
660698 F20101118_AAAEYQ liu_y_Page_113.jp2
b3be5265ac4b67c5a9e78f2cda01ea6c
bda8e33ef00e5aa1f86c8ff280fb29ca9083e617
F20101118_AAAFEK liu_y_Page_045.tif
028d03c727848d8ae24bfa07e7134430
48c8652242d5baea1083607acaa7ae80fee40ec4
1051916 F20101118_AAAEZE liu_y_Page_127.jp2
1680a773098ce1c4bc112350901ab77e
5bda179f3c7b30d8156379dda26217964645dc56
26045 F20101118_AAAGIC liu_y_Page_094.QC.jpg
53769053ebc3b506c0165ff7c8edd26c
f8dcdeab49b2922c2332598ca361ecd7b8f36df8
4615 F20101118_AAAGHN liu_y_Page_086thm.jpg
0459530c9447d3ed96cb1dcec43db7df
ecb82d7bede8f61f7f97131808dc946d1835cfc9
5701 F20101118_AAAGGZ liu_y_Page_079thm.jpg
36ef07d54b779547a053679f7643efb9
204f617ada8a13b16875d7843c59cc351f168908
971636 F20101118_AAAEYR liu_y_Page_114.jp2
eb8c3447cecade2b4ca12c73374f4dad
79e2777ac45e33c5b1ecb4b47b96ab15168fc062
25265604 F20101118_AAAFFA liu_y_Page_061.tif
eef0a2cf816756e8a0b4f702301f9294
1eb306cff62b330e0a6b63e2b7e4b2a6eaff09ab
F20101118_AAAFEL liu_y_Page_046.tif
645adf0a5a770c9e56936a482221a63d
ce1ff248db83edb31a871edabdc94e28fdecdb17
1051979 F20101118_AAAEZF liu_y_Page_128.jp2
2d31a26de08853f813bf487718a09ba8
5bdf4225f8e31d3db0ac067e274db55588304973
F20101118_AAAFDX liu_y_Page_032.tif
d7973b4fa3534df5b011dd10753a8a40
ec46c201716671a2e96844129907be3984d868d6
6992 F20101118_AAAGID liu_y_Page_094thm.jpg
0bd0ba3fe6ec0c1396af61b13986ac3d
8ed8181c89e5a8ed6122102998f5ec0d43207c90
14454 F20101118_AAAGHO liu_y_Page_087.QC.jpg
6931a211909916f3dabfc394f49406c7
e728adfa543e0fb564058ce23ddf4d3a6cfbce54
286628 F20101118_AAAEYS liu_y_Page_115.jp2
7270401cdbac1bb6ce937debf682fb88
6aeb3cbc065de71276b9d864e5cee2efd22ad7eb
8423998 F20101118_AAAFFB liu_y_Page_062.tif
a4eabe5b1b0b5188cd16c9573396dcf7
dfd1758da215644383a0904164733a9e15d88327
F20101118_AAAFEM liu_y_Page_047.tif
1207cabf4339e776655a22f3c4a2e16c
8e0992b830464cbadc0ede8d18b3ba880d8b67b9
F20101118_AAAEZG liu_y_Page_129.jp2
96761c3d3dde58d7bf91649e1a5db5d3
53b585012411fb8a7b1c7505f27a3dfcdd2a69d6
F20101118_AAAFDY liu_y_Page_033.tif
390927ed96ebc3b19b57f6f7ee3d6112
58b43b7923d84266e85ff383911f92fc91fd1228
15388 F20101118_AAAGIE liu_y_Page_095.QC.jpg
fbdd1b73ab06533acb44a046983533a3
c1388bd866842a44d1c663674a1d368fd8db94e8
4440 F20101118_AAAGHP liu_y_Page_087thm.jpg
5f807e97f0daeabb9df601f91217330b
90c97e8a1d420b9fe85304247649a912079fc982
F20101118_AAAEYT liu_y_Page_116.jp2
e51d16a70b3d3621ad3ab9c5917f6f96
63280d2de0a37d3a92bc32b4ae5b9b2d9b530244
F20101118_AAAFFC liu_y_Page_063.tif
bca85147061788753f47794dc93b4845
805f7bf921a59f9e31f1a0412c746cf2e507445a
F20101118_AAAFEN liu_y_Page_048.tif
4b38b3631e9f4f2bb4a4c8ceb14d043c
c279cb3368b8676d220df636e008aa3fc8f8fb80
764742 F20101118_AAAEZH liu_y_Page_130.jp2
c1d7a8dc0916f794c04b653b019d7c98
079fc6b362f2087a0cf5dd6360e5b72a36a3c27b
F20101118_AAAFDZ liu_y_Page_034.tif
761b8cc8592fa3ef1eeb8c83089cd0bc
2fd1cd8eeede6d1f1aa9d9d586856ae00872bcc8
4390 F20101118_AAAGIF liu_y_Page_095thm.jpg
70b933b5505ddc02897b6e4c1ced518b
ec348caa080599551a935789b04dd715fa589ed1
20946 F20101118_AAAGHQ liu_y_Page_088.QC.jpg
1d11b3de8d077941e68da68317efd0db
036f201c1f89158a77e44916f9cf6b5afdf588fc
1051957 F20101118_AAAEYU liu_y_Page_117.jp2
841bed5e2d5b8e2f958c32f443e3f09e
8a96fd1dd2cc3cd9d86499cc846171aeca3db18f
F20101118_AAAFFD liu_y_Page_064.tif
992dcd45a5fb04f4f9da78f7427dea27
11b0a82f29199c7aa6f6cad6cae7d4d106a3d42c
F20101118_AAAFEO liu_y_Page_049.tif
86c7906ec3f994e5111e45315d16d0c6
278a378af0dd6e7bd5645f28af3101ac2f006772
829485 F20101118_AAAEZI liu_y_Page_131.jp2
b6a7d8158dae598bc196819e825b96ba
1395a145c2ed2ea6a9fe6c9966f4cf6ec6f5199f
11202 F20101118_AAAGIG liu_y_Page_096.QC.jpg
b19da349111f26aeccec33f94c7354ed
879cc31fd360d67043f26364efc6127f719be871
5970 F20101118_AAAGHR liu_y_Page_088thm.jpg
860b700129c65e43adacd74c0bde211a
879c4e69f6ffd9715bcb8bfad277706680d0f8e0
1029670 F20101118_AAAEYV liu_y_Page_118.jp2
9dc9d5a9d5b2f82c7853ec83ee2ad82e
6fd378587acfa941685a71566ab25942c7e7b287
F20101118_AAAFFE liu_y_Page_065.tif
020a49163502b2d030b1cd87e66a009e
ec82d2d4980194ecc8a9444e89f8f11d4a073d8a
F20101118_AAAFEP liu_y_Page_050.tif
ef838c2cc6cf757cc5cc1ad87efa0c47
e53dd5f38c82b29e63946694e5cff55993bff72e
F20101118_AAAEZJ liu_y_Page_132.jp2
493ada2ca0999567de8ca3128ee323fb
05f325c18a5c234ff0230ae658c39178e61b2f19
3323 F20101118_AAAGIH liu_y_Page_096thm.jpg
860e7e1633f35843cf1b7a2c5e23049d
d55817911402d7e465df52e32bbfb9c84be58ec7
23823 F20101118_AAAGHS liu_y_Page_089.QC.jpg
ead5af22689d7046508c444a20748efe
ccb7d3522789364bdf2779e4357868f46daacf88
863198 F20101118_AAAEYW liu_y_Page_119.jp2
460507eac6ad6ab95e879ab9ab2efbb3
82e9bf26dcd5cc05bbce18c4326faea5b5a22809
F20101118_AAAFFF liu_y_Page_066.tif
8ed30c67094f029f5b14e9abbac31142
68e6955559c14ec72ec818306a363828f0b8a002
F20101118_AAAFEQ liu_y_Page_051.tif
c45a6ca09c29acd3b18d21104bbf581c
e791899cbe0c4f110abb2f727b4dc9fd66495d36
1051966 F20101118_AAAEZK liu_y_Page_133.jp2
01ea2f8ed76c81b776058c6dc893f955
c8c53e5ec1ecf4349dbc688431521f558d952bd3
19302 F20101118_AAAGII liu_y_Page_097.QC.jpg
b1f2c6d826a801448427fa939d270f7b
e9b15ea85cf56c7f29ca1ccef3100519d78cc314
6996 F20101118_AAAGHT liu_y_Page_089thm.jpg
1b4f208654526ed673dcb2368884db28
c2ff741bc98c413a38201f4f209a8dc2ec03ebde
F20101118_AAAEYX liu_y_Page_120.jp2
3aae27c9fd5936ac5bc53b5b6782c209
93bc6e19668fc797d1f7e067d0b760c313498627
F20101118_AAAFFG liu_y_Page_067.tif
d69a7884fc9daa945924b13e367cdbc7
7422e79d0d9a1e424f64e491ac735a197b31ce25
F20101118_AAAFER liu_y_Page_052.tif
d3177b3b8d1de629160a84017bb5e2ee
c7f1eb032137eb04ac35ce1174bc75edf6f3595e
868799 F20101118_AAAEZL liu_y_Page_134.jp2
9c1b93193ec850a5b758b0a79035032e
716994b973d9f0e443f96a9b961c30c58a1be5fd
5363 F20101118_AAAGIJ liu_y_Page_097thm.jpg
df8cf80883fddf05214ca7c50420cc60
68bac8c74a9a7cb52643780785bc9dac78f9f8cb
15452 F20101118_AAAGHU liu_y_Page_090.QC.jpg
841f748041de44917129b360ad75bc40
f4b4458a52d6fd677f3b40640c11e1a384b4159b
1051842 F20101118_AAAEYY liu_y_Page_121.jp2
f3b9d057a6dba2ef63b5d26cf08b1288
f68ba61adf7a26d86b7ffab21a1da814b5c09dc9
F20101118_AAAFFH liu_y_Page_068.tif
057d019769f3fb7a7c6e8c16ed4cb165
15520ff774b9f924623a2fb76c83c8ee1887684a
F20101118_AAAFES liu_y_Page_053.tif
9f152fc56f70d627cbd77a7db1b3af58
5bdcff53bea6b76b821d39c8577e31c13f5787f0
664625 F20101118_AAAEZM liu_y_Page_135.jp2
ec1c0f701c6c7bd32826ff9b42ae42f1
f15cba667cec2a7c07166d55eab884deea3466ed
23485 F20101118_AAAGIK liu_y_Page_098.QC.jpg
fca5c0435524b77ba545f0579f5c8ffb
272a6ef8f87c90332d52e5d1217f17d8608dc189
4830 F20101118_AAAGHV liu_y_Page_090thm.jpg
d21ec265b05efbe75d0b6fa7d097528a
a5e4e2c9409da23a03c6599e960e7887a5463568
661264 F20101118_AAAEYZ liu_y_Page_122.jp2
89465d65d1143180bec9e952e4cb044d
78e09b6c45057300573c063cea4af7091f82c426
F20101118_AAAFFI liu_y_Page_069.tif
b35af91db5f480a5cdf4ee0838bbb5aa
0acb8cb6dcacd1cbe8c638ee9c9371bf5572f81e
F20101118_AAAFET liu_y_Page_054.tif
ad83a2253418b4eeb12689c73af967f7
3250da4a659f67d32c96e20d1f4be7e24e770abe
815427 F20101118_AAAEZN liu_y_Page_136.jp2
013287970d1945a0ef34240ea4b34076
163a81c581fb328acc9ad11437e20974190da898
6430 F20101118_AAAGIL liu_y_Page_098thm.jpg
cd26a1d5744c9c0fe55307fdc7aa20d9
edc04f5bcbb9fdac5b7c466a7c40e06592c3d064
18347 F20101118_AAAGHW liu_y_Page_091.QC.jpg
aab73acc25e61a4ef38df60ee818a072
a3194eb9d9b2fc38f135c69087112b4072d7f8bc
F20101118_AAAFFJ liu_y_Page_070.tif
ad50a89b30b99a44bd9e53a0976c84ed
ab29e9f44ca085aee66af897d8adab5bbeeabbdd
F20101118_AAAFEU liu_y_Page_055.tif
8bafa091e2ad4d2ff461fb79277f9148
85913a5e68334308e4748a424e21fca05335f64e
F20101118_AAAEZO liu_y_Page_137.jp2
04b67385760e908e93dfb3e6d6a68073
c6e664ed16ad6244fea42310c1e4d5031648a718
16036 F20101118_AAAGJA liu_y_Page_106.QC.jpg
505e6952dff0f620c594238895d2331b
d1a46c9f519edad9e84527257bb014bed31c5de9
20754 F20101118_AAAGIM liu_y_Page_099.QC.jpg
f74eb130f34cb4520ccf6c7cabc74ee6
bfc393019e93bd63b40c44a0da19dfd956987a9c
5604 F20101118_AAAGHX liu_y_Page_091thm.jpg
26b5df87663ec9b7214c2fa1400f6eb9
dda55817962c05cb9dfa2d5ce42c9c4e64bb01ea
F20101118_AAAFFK liu_y_Page_071.tif
8b46e74c0ade4b00b2bfe00886f0b833
f2516452dd3ec904b1a4ec7c823805fab9790780
F20101118_AAAFEV liu_y_Page_056.tif
e7047bec25d97658fc96dc20e06459e0
a9e70ec68fcbbb18694820c53e8e5b5ac46ba6ce
713555 F20101118_AAAEZP liu_y_Page_138.jp2
a2d60aa3be2c3b2904847a9a48688774
42da1fa9c655a6eaee9701599e9cc5f737cf49f9
4818 F20101118_AAAGJB liu_y_Page_106thm.jpg
9b54b9e1ee3c6ca61856f254cb3a0c79
dbde3aa9afc46ff02d2710c5cf90deec42380fe6
19775 F20101118_AAAGHY liu_y_Page_092.QC.jpg
3f574519014daa121c73b5d4969050db
60a4834e1a22453aaec222b7e3aaf3dc8b3ab4e7
F20101118_AAAFEW liu_y_Page_057.tif
3b0fa67bd220438a2ddb972996f674fd
ecd15db3c6cbc78f504b0d91ee5b3bf4a40b55b0
696286 F20101118_AAAEZQ liu_y_Page_139.jp2
d2aec1a39007735e8ef7354204429eaa
554fea955b9a5fa8b5978f34d3a1881212affc57
3054 F20101118_AAAGJC liu_y_Page_107thm.jpg
992ab059d91ac62e2fa458a09be83b1e
33b3ad48e20827e928eb1e9de14aa4e65e796135
6148 F20101118_AAAGIN liu_y_Page_099thm.jpg
9716bd6957ed8ad8cdbd8a15af51965e
c44a3273a23d63f95056c97da7fe6895685b9970
5472 F20101118_AAAGHZ liu_y_Page_092thm.jpg
4e124fe8d4b8f17c88f56428c15c27b2
e4b4b6e5c653afb13e288f92e5a2bd42ef65bbfa
F20101118_AAAFFL liu_y_Page_072.tif
8c8f9cc33ab13337a92dbfa7cd5808c8
dddc29d9156a4a1f9533639e1dd08f3315c9a74c
F20101118_AAAFEX liu_y_Page_058.tif
702bacc5b165180166b96dbbbc241954
89a20fdf8ed276055d7185029770ff006fd59d65
781218 F20101118_AAAEZR liu_y_Page_140.jp2
f04827cdbb9a3ec47fd88c5159e66752
4ab120e5ae46327c3f283679cc42c111adf58823
F20101118_AAAFGA liu_y_Page_087.tif
63cfe546180162a1494c2888906b8010
d7d64a7f4f304eea44a6695d977647501e2a807f
14859 F20101118_AAAGJD liu_y_Page_108.QC.jpg
56df968123103e8086eae94163a60b9a
15605c4a0a1f5b301bc73aa7fa14874bef19c7ba
20314 F20101118_AAAGIO liu_y_Page_100.QC.jpg
ded23e7f475bd047d17d4a3935993fc6
ed64845f6a3456b48e277b26414f778fd09eca3d
F20101118_AAAFFM liu_y_Page_073.tif
67d7d06ac1e1df62fe407ddc97cd0a11
c81fe87bf85a0ed4116e9e30a2697e88a7a45dda
F20101118_AAAFEY liu_y_Page_059.tif
be283219618fef846d9bb5d402a36861
81e4e9504a85d9c2fe0f47bdc77525b45068d27b
815689 F20101118_AAAEZS liu_y_Page_141.jp2
825b0400c3a7b8dcbcf246b8b11078dc
9bc231b3f31cc25b80a712b657c814acb17393fe
F20101118_AAAFGB liu_y_Page_088.tif
7e512e0e1064c0122f1f3ada05900db3
cd69b495eb5c89a2700a3dd322d1c1fbac749f4c
4284 F20101118_AAAGJE liu_y_Page_108thm.jpg
31e583c52f0b7f4b108e1ce4244b5e3b
8a5fad1985e92f02e6f2eed28915008508a2a068
6160 F20101118_AAAGIP liu_y_Page_100thm.jpg
70680ad65d8c339811478d096c87b110
45c2e6ecb4bcf568c5cfb10131a1a10f7c06f84f
F20101118_AAAFFN liu_y_Page_074.tif
6a1e9fc8834a5d401bcd68542687ea02
7fa8968fd9fa670a8e07700ab70f55236d25f0ac
F20101118_AAAFEZ liu_y_Page_060.tif
007aea5f55f8654add9d5aecac8ee313
b8895cc8339910356f834aed161a79809805e160
830132 F20101118_AAAEZT liu_y_Page_142.jp2
520f289e157c32464cd82df9693c2751
1e27c4ac0da6076a2f1805289e7175e7f107ef1c
F20101118_AAAFGC liu_y_Page_089.tif
c8092437f173099197e345c311d342a7
5a7c1bcf9d15462bb86bcf1dedaebc3d7052be7f
6884 F20101118_AAAGJF liu_y_Page_109.QC.jpg
5622c4b143c19ca013e740cf1769e610
53ca9ee2d7fdb6c0993b52cb06ccbb51fd5f5d00
20180 F20101118_AAAGIQ liu_y_Page_101.QC.jpg
11a52da9e1bc421ee42b4e3bee450a22
5b4f004299e7e255ee254e1c7a0a6b1de9c49114
F20101118_AAAFFO liu_y_Page_075.tif
70717e07766bc9e965586a70ace3be8d
070c251e96a4cb32e525bf3b36a51fad2348cc38
773132 F20101118_AAAEZU liu_y_Page_143.jp2
b20c3a7f0a97410caff030912d0e567c
f91d9b81b5886ebe3b64dd2a8635826cb751baeb
F20101118_AAAFGD liu_y_Page_090.tif
78251d747bfd257cd3762cfd95ce1c0b
b028737996aa85b3277734ca4088a362d3613a88
2113 F20101118_AAAGJG liu_y_Page_109thm.jpg
b8c3121539435a58b5c9193b24a2a123
fcf3bdb7a6c8f772c317dc79851e6bda81b89c34
5782 F20101118_AAAGIR liu_y_Page_101thm.jpg
7a48a478e1377cf89f8fbe7281b74689
ef39cdf7339b1efcbe959e71490f3bf990b7b55d
F20101118_AAAFFP liu_y_Page_076.tif
7b56c82ee2d7d72ed9fa4519ee5561ee
7dea54fbe8b3d7a20f1022ea6cee0a28150c86fe
765580 F20101118_AAAEZV liu_y_Page_144.jp2
bc731d9c78c5a190f752e780ec32c3f7
4e1b5de32338e2f5e282978aebb6ab99383e4bae
F20101118_AAAFGE liu_y_Page_091.tif
a9be0a8e18fbf57c366e2272de9fca16
ce9621ee7913bdf6c06a681057b7fb3663bdd92b
19486 F20101118_AAAGJH liu_y_Page_110.QC.jpg
70d2d10cbd84382e7d0d74af99f38293
427ef010aee85000fd5ed43e02488362db1aed2d
21798 F20101118_AAAGIS liu_y_Page_102.QC.jpg
738eeda7a3cade5e261479ce203fcda5
3e4d2f920c657f7c885039fdb8364142b208f30b
F20101118_AAAFFQ liu_y_Page_077.tif
2ef0986b66e93efcbca58b6fbac4528e
2c7bbd0af3fc3e744ae39bd5839cd8bd525fbc8b
1051906 F20101118_AAAEZW liu_y_Page_145.jp2
8e46a19bd5518f9070a4871037b9eaf1
8f1c9befb7c4e67cc0cea590f07fdb71fb516531
F20101118_AAAFGF liu_y_Page_092.tif
219c7b569ac9377da93d1199c924d22c
8c0421adf743c81e03aa4857bbc52c545ece0e41
6016 F20101118_AAAGJI liu_y_Page_110thm.jpg
8f440d10ff639e89e0174cdb56a5463c
fdadfd98795ca04f6556bcc1252c6aa8a5225e38
6352 F20101118_AAAGIT liu_y_Page_102thm.jpg
890af77e41c4477fa0e4c5fb461fddd9
f9fbcde808618bfa6e9bd769559070fc80c29a22
F20101118_AAAFFR liu_y_Page_078.tif
b3e2ba8f4fd97b347d5078a6516175c3
36483a5ce0a27d82fb2017ce0a34788cc51dc0d5
F20101118_AAAEZX liu_y_Page_146.jp2
d16121a161d4be087b311c108b8a8910
95fd6ec3e28a4c8ac885cf3741bbae1ca9a69971
F20101118_AAAFGG liu_y_Page_093.tif
9f59226166ba8cc64646ea1178197e57
a88c938d3012880d5b05a470d0741e3c5a7539ca
20447 F20101118_AAAGJJ liu_y_Page_111.QC.jpg
e83a8bd1201133e3b126115a0b5bbe30
275e0d2092b18045bdce2ad155792b407d7da433
25047 F20101118_AAAGIU liu_y_Page_103.QC.jpg
436c19b4ef0ee76acd60a5b4c741c0a5
48ae68f0ff48bf3c302635290973f5006c2d2259
F20101118_AAAFFS liu_y_Page_079.tif
abeab192aa32975d45e32a5b57c14324
649500518a4f6bcab00e1f8c2e0725ae81689d5d
F20101118_AAAEZY liu_y_Page_147.jp2
42d495c61a7b610383dae35499990863
3486561588072c35904e7a3144a56b422e2ff0d4
F20101118_AAAFGH liu_y_Page_094.tif
4ea7933bdae41c51a82e0722c43f2264
2c7f53d60b7cdca73635f5baffed4cb4532126dc
6216 F20101118_AAAGJK liu_y_Page_111thm.jpg
0ce1ece8a663da91b3435dd88d2ad6ee
35b96eb25fc4f4779d6590a0721f7f917e729aeb
7156 F20101118_AAAGIV liu_y_Page_103thm.jpg
ac3297fc0d0e68187157e2a3460ef288
b9962e232e6deaa46991507c0ad3b7797c603af1
F20101118_AAAFFT liu_y_Page_080.tif
40bcc2f4cf9f6e276dde2cb17219a9c0
a30a99d50261f7e6a5b0400cdcdd813401b81a3b
1051907 F20101118_AAAEZZ liu_y_Page_148.jp2
3f32cd4a625856ed2c5567dec8755c6f
d214d7fc64f92b230b6019eb22a4a4273780ca53
F20101118_AAAFGI liu_y_Page_095.tif
bc9b85f3141e6f62d75fb6aa0b345748
ec8b58d61de11fe495757b5bdea4d939297b6e2d
27748 F20101118_AAAGJL liu_y_Page_112.QC.jpg
aa491390f41725fe266f7791e2e360a5
16c060db96bd01be292d5170665fbc404cf050a4
27185 F20101118_AAAGIW liu_y_Page_104.QC.jpg
2ae9d853ff9e0daf44dd34a6e5220c30
65bac11ab0630498df6adc1364cbddc39e7088b0
F20101118_AAAFFU liu_y_Page_081.tif
cd13321ed163410ad2a9d27d55224a0c
48fae82551d32691e913f7673480f2cca6508f05
F20101118_AAAFGJ liu_y_Page_096.tif
27256ec91f5174c0ed113e104c9da270
43610ed193b45434edd135bedc20110cf4093647
5742 F20101118_AAAGKA liu_y_Page_119thm.jpg
892782a55fbb0939ef82cd12bc857f11
3c559dd619fa551346e071bb3150cb93b4130ddb
7442 F20101118_AAAGJM liu_y_Page_112thm.jpg
7498fb5af7525e6baecbd4cb970879a6
da5ebf53bc0614d0fe0d79f3a3a82365389ac9cf
7459 F20101118_AAAGIX liu_y_Page_104thm.jpg
c554ceabd863754757d4b3b3a123f25e
ad5c56a6de77ddb5586fb6268e834ec1fdd389dc
F20101118_AAAFFV liu_y_Page_082.tif
cc054b4354dd3cb991d529f7a9b49279
e876107d9f665e44238beecdbd8b1929495109a8
F20101118_AAAFGK liu_y_Page_097.tif
f70d7c945b616a8d56a0b122b00e5cf0
5cc46b572d23fdbebde82b03e7c578dd8b55ab02
25056 F20101118_AAAGKB liu_y_Page_120.QC.jpg
a8dad56b56df169405ab4d1a6b0ac038
3044f2ec933200cecde356c5203bfa688d9104e8
15881 F20101118_AAAGJN liu_y_Page_113.QC.jpg
37ef734194c3b55b1f1ea4c05dac9854
7a72a2eddece9d36ecbba81a35bbbb596ba43075
11506 F20101118_AAAGIY liu_y_Page_105.QC.jpg
ee402566d7fe151aad8fb35503a02211
a48d3ce739a765ba71a6cea0d661b607fd75ac1f
F20101118_AAAFFW liu_y_Page_083.tif
2c4783ca54c67612fe90aac77e80990d
2ddacf5da1291eb3410b3d3c99ef8142b3cc9ea5
F20101118_AAAFGL liu_y_Page_098.tif
df8bb8336153083743b3d98280d2773d
9c444c62c4fdce89ab15f75d77db829e56858820
6861 F20101118_AAAGKC liu_y_Page_120thm.jpg
ab7dd71a352a14312719f602c6d18e0b
c487929d8538df5b8609e7636626509d63f03386
3200 F20101118_AAAGIZ liu_y_Page_105thm.jpg
27fde349311bda758a81cbc656759973
552dabe61a9baf3f924b6e53153af60af6e5fadb
F20101118_AAAFFX liu_y_Page_084.tif
72d7ed6ef30832ddc294b9b93ec76884
e8a490d41674926e2953d6181550afacb1b76f49
F20101118_AAAFHA liu_y_Page_113.tif
6469610488ddde2ec3c18c8c860750fa
64f26d8eb48cf4be15a5a17e3cdf163e0f8b3dd9
22999 F20101118_AAAGKD liu_y_Page_121.QC.jpg
183a9cfa9779661a31cc6e1a6e19706a
6b143b79d2adaf3830d366142c0cb5d164923ba5
4658 F20101118_AAAGJO liu_y_Page_113thm.jpg
181acd5b6206541ab1500f0cfc25fde4
fbf9199bd7b65266ec0bf8f0e6f857c87c259d55
F20101118_AAAFFY liu_y_Page_085.tif
fdcd8812a3770630ce266bf5c52774f0
a37443e6f94b40bacb8556f1d9b80521eb76fee4
F20101118_AAAFHB liu_y_Page_114.tif
b1ccf9d04dddc5b38857cc825045dcf4
4e227a1807ae53e9637a676828c954c94faace67
F20101118_AAAFGM liu_y_Page_099.tif
020df032acdbf46b32fd4605badcefeb
97e7823954eec184c42bfad679a0b7c6b5769997
6538 F20101118_AAAGKE liu_y_Page_121thm.jpg
99095dcbeb143746c4960e92a24d3262
df370f81079f6b46c9db53a24948c19afefbf83a
23130 F20101118_AAAGJP liu_y_Page_114.QC.jpg
5832ef0fb89e3fc40a11158713c56600
d623e5e9c92ddb387ca7a9812e3f049283ba27c3
F20101118_AAAFFZ liu_y_Page_086.tif
4855b978e7f3014b5b68bad5c6b5c83c
129d69fe20b9f5add8d58045439ee69d5ebbf37c
F20101118_AAAFHC liu_y_Page_115.tif
8e3b06a34c1ec595d6754c25f9a79813
7dbaba6c9e74f384eda30e212311dc3b967945d4
F20101118_AAAFGN liu_y_Page_100.tif
6af26377e2101f155c8a3bdef141503c
42b26d200ac5682db737b2566abef7853b34f549
16756 F20101118_AAAGKF liu_y_Page_122.QC.jpg
bb3b99d8077b37fdf2ef6a5f97c721df
17bf4c8180fe705582f44ad8ce4cd817cd650b6a
6293 F20101118_AAAGJQ liu_y_Page_114thm.jpg
df21ce6c68c0c952aa19ce60e09c4d9d
c6827dcf2516a9db11d463df5e9a03b2245a952f
F20101118_AAAFHD liu_y_Page_116.tif
3b3638c2ecec2651648d392e55befed3
9f23bb7ed24df2f441056f7227e0e70b731db466
F20101118_AAAFGO liu_y_Page_101.tif
1e6d4e8aaea2cdaf336e8facd4e84cad
18fa69b8f9df418f8f3f0a8bbff45c5e5478fac5
4675 F20101118_AAAGKG liu_y_Page_122thm.jpg
9f3e9d053707e49e5da5973c01130aae
d27891219ad764a9be24c9032aee6df82cd3be6f
8498 F20101118_AAAGJR liu_y_Page_115.QC.jpg
84b626ce7d3731a0f994b7a363e0bfb8
455dc597aab85698c5b80669369e365d901f8733
F20101118_AAAFHE liu_y_Page_117.tif
4f6e4b6a5d6ca678067174ffffe6bd94
77e3eb1c65dd8dd683391a84242bc7fddc901009
F20101118_AAAFGP liu_y_Page_102.tif
f6461ec8366261f2b463f3af3e938d7a
7095c82ad757e8a4c185d25f6b63fe56cbdb17b4
14444 F20101118_AAAGKH liu_y_Page_123.QC.jpg
e9869375f44fc2bdfabc92d53f388414
81eac7f137b489e185aea61d8ea9eb6c86051aa7
2563 F20101118_AAAGJS liu_y_Page_115thm.jpg
839ffffb55aabb086e0f53b2b4be46be
42a0be1e485a14ab78ea0158e032deb99523498d
F20101118_AAAFHF liu_y_Page_118.tif
99c42b18a30cd3430c399b3194fac9cb
8ea8a02cf63dd9f3b5d85d21c695fc650b46640a
F20101118_AAAFGQ liu_y_Page_103.tif
02c279375ba7c6a9d29ac97f4a5dbde7
653fd8ddc39a11e3ee58387116d6065c77f586c9
14440 F20101118_AAAGKI liu_y_Page_124.QC.jpg
07a6877d1514410392f23075e376eb24
cc03a4cba6fd78ef26bd81906c0db805fd3f9499
26112 F20101118_AAAGJT liu_y_Page_116.QC.jpg
9175302983fe9290af59578f1b7d9123
92ef69315f00d6763de326e47fe2812846498216
F20101118_AAAFHG liu_y_Page_119.tif
e4ddc5174a7d711097ef60987977089f
c3210c70d241b9b62550e070fd7c2bfc277da581
F20101118_AAAFGR liu_y_Page_104.tif
2cb595d4a9992490d76489a05d72de3b
634b30862d840863146e2192b9e09eefedc62c46
4050 F20101118_AAAGKJ liu_y_Page_124thm.jpg
a44767a62a148a76c99d9ac8ebc057ec
bfac61ade9c65c26987f9b586afb5f08aafce01f
7276 F20101118_AAAGJU liu_y_Page_116thm.jpg
c74658b08f84d447182af0ca8c5c0b88
ba28976488399bd49ae18a027a7c94029922a323
F20101118_AAAFHH liu_y_Page_120.tif
c2a1d0f27e75fb887d96a7d87ac3b1e1
0b6f99a9f8b0ed2be75b5aa3ac40976c0b083ba1
F20101118_AAAFGS liu_y_Page_105.tif
969ff9f01e8297462d9707f42ea80ac3
3c33454c5e3d58c5ba13806d36390686abd6dc47
20019 F20101118_AAAGKK liu_y_Page_125.QC.jpg
b1198d31d3749d8c8dfd81d78a3728ae
a85a11056f8f511ce23351e37f19e9f1cd9fdf3b
23650 F20101118_AAAGJV liu_y_Page_117.QC.jpg
2b0f6109dca08e7754ac01b8ff356100
2c71c61bd2860fcf869247daf7eba5f00b39fbdf
F20101118_AAAFHI liu_y_Page_121.tif
99ece976f35ff6f728d5678a1b6a4e6b
69db7551699fc070f3e05b24cd609d2f26f08f29
F20101118_AAAFGT liu_y_Page_106.tif
0d3d0924cc7070dad76b96f72154dd16
9198f6c781560678e5a85c8012e8b5ba63b685ed
5536 F20101118_AAAGKL liu_y_Page_125thm.jpg
b854717e29b2336eb8c8d9f874bb5f00
5d79b6dee94b61b3992dfdd8e2ab6f565bb51737
6572 F20101118_AAAGJW liu_y_Page_117thm.jpg
e5de0a101639a571c0b8a75a53947be5
f9143e57e16f091ba1989defc2f2e0d8d52a3b78
F20101118_AAAFHJ liu_y_Page_122.tif
775ecb5894a854004c4beb66056dd5d5
b0598fee023b6434c9f18fc300a907fddc17e765
F20101118_AAAFGU liu_y_Page_107.tif
4f59dbebe7cbf49e4902f6c1a29158fc
efbed27f89cc7cc299525c3eb755fa2f10aefd3b
7204 F20101118_AAAGLA liu_y_Page_133thm.jpg
2d0d32c44fcf2dc5ead3a8c82a306848
1e04240e5b033362bb0495e981c70ee11a3ccdc4
25966 F20101118_AAAGKM liu_y_Page_126.QC.jpg
b4ca93cc9f511fe41f304a0cc31d2628
434fe57bba5af6685216621151bd1ec39ab2e2b0
21593 F20101118_AAAGJX liu_y_Page_118.QC.jpg
36a4b6061dfa8c4b7708217d07618516
c5a77f076234b90d24dbe405a91252ee8fecce57
F20101118_AAAFHK liu_y_Page_123.tif
01d6412c6de3f5b81965824d64a7a8aa
d68711c40470c1afefaffb17f4754717a0cabb4b
F20101118_AAAFGV liu_y_Page_108.tif
184e90c81eb7f7d8e5c3b771b8362056
95bd85b390ea371c5264d7ef9562a1dc5194f390
20673 F20101118_AAAGLB liu_y_Page_134.QC.jpg
9211ed17d4e117c8199f60be4d4d01bd
3aa7dc3a841b322803076061e07edfa2fef6198c
7161 F20101118_AAAGKN liu_y_Page_126thm.jpg
7a750035b8decd8737033484d8f134a4
027f7e3bc17442b6ceb300abbca739850e71cca5
6344 F20101118_AAAGJY liu_y_Page_118thm.jpg
631675c86aab8e57703a96427002bf2b
2566bf94ee27e5d277e32e6a1ba6e9f38a768f23
F20101118_AAAFHL liu_y_Page_124.tif
7f3db68223b2b6c37f1ec320f0f7ccb6
caed9480007b57b9f230a06fd80cf66a8716ecca
F20101118_AAAFGW liu_y_Page_109.tif
2312ea9f15a325165e9773f10ca85242
fd6eca0cf457e19d1cb20f1cc9ca7736afc696f2
5783 F20101118_AAAGLC liu_y_Page_134thm.jpg
f88905719fae21d4f515a5a30159d9f8
d896517b18703903a9cbcb51f9da3f963058efde
17068 F20101118_AAAGKO liu_y_Page_127.QC.jpg
c5b8df8224ffe30ddb0621890deec9f4
d2abd56ebfa129563ee2dee1ad19952572b76def
19724 F20101118_AAAGJZ liu_y_Page_119.QC.jpg
efa61acdc1a14319f962a09ab063e069
05fef71de061cd58f13ef46974d0955870dadcbd
F20101118_AAAFIA liu_y_Page_140.tif
37a2e5f7fa2efb1334c7754c41ab07ae
3cc311a9cddeb0e75f090c120948b238fd7a8012
F20101118_AAAFHM liu_y_Page_125.tif
f9c714e07e60daa534a427718b929655
6645883c9aac9cb99c4beaa3384097772c1ae7b1
F20101118_AAAFGX liu_y_Page_110.tif
4a283fe5567dea1381f4790dad7f5ba7
deb6ba366a8d9c365c89d5bbd684493d6b2004b8
16653 F20101118_AAAGLD liu_y_Page_135.QC.jpg
cab2d525f153479eafe324bcd2be55eb
fe030f100582b6b71c89be94b511cc6dc2c5ea45
F20101118_AAAFIB liu_y_Page_141.tif
7cecb326968254003e274bf934bbdcde
6c5cf541577c981fc4a02c21a699f963f499e399
F20101118_AAAFGY liu_y_Page_111.tif
59c67e8614fdb0f9310b1f49112dc866
3c4736417128093305b30ca212e7cbe33178fd40
5354 F20101118_AAAGLE liu_y_Page_135thm.jpg
e17afd28c1e9ae10cd020e7744168fec
f2de14036f3f3802088e7bae993b22893d27a173
4568 F20101118_AAAGKP liu_y_Page_127thm.jpg
6b55ec11ad436ec9e5423da2812cae79
7a539f2651f65a9c171b008280527d5c24faf377
F20101118_AAAFIC liu_y_Page_142.tif
a9f8315197a24e98326465a95aa8fe41
2206228591b1c58fd176e0cf856b46f014e084e3
F20101118_AAAFHN liu_y_Page_126.tif
8b68a4cde4cee02a4e82f35d2f9e1634
3a137ed21d6a28f29338cd4f53557df670f02c12
F20101118_AAAFGZ liu_y_Page_112.tif
56bbc40d59df99cacfb19f2c1078f9ef
ed7d13493f56277e357bad7e7d9ec2a8b409b49b
19194 F20101118_AAAGLF liu_y_Page_136.QC.jpg
8dc169fc604d6cf1b1840288961e7536
59478947d8cfd81ebd1b89d09af8f6a71c98726d
7063 F20101118_AAAGKQ liu_y_Page_128thm.jpg
edf853f2843d01ff04db564611a03b59
946feec6648897952eb0441b76d7cf82385c424f
F20101118_AAAFID liu_y_Page_143.tif
898948aa91b0280da4aafeff04ec29f8
0bd7e623ada22c06ed1178abbb4150e0341e9b97
F20101118_AAAFHO liu_y_Page_127.tif
16d7b24390293e722ef543fffd7712b2
e2affdf29109f9c7a16fc32397263154417a8405
5796 F20101118_AAAGLG liu_y_Page_136thm.jpg
aa0e8e68b4e5350638d8be22f35ce9b5
654eeab8f9e3db16fc58148ba62220452b6230ef
22590 F20101118_AAAGKR liu_y_Page_129.QC.jpg
505ea44c6f6f52bedbbcfd5e321ce00d
8b12c406c9566a8777d3d9d439c7bb6eaddbb8e0
F20101118_AAAFIE liu_y_Page_144.tif
18597c997b12c5fe23a1fd87b47cb0c5
2496895c8c45f1f90ca027366e5269df844a83b3
F20101118_AAAFHP liu_y_Page_128.tif
83b13f613f12c62ed65ef9ed307a88a2
1d10c177fb17b417bf2728971e6ce20356d18841
26716 F20101118_AAAGLH liu_y_Page_137.QC.jpg
3055ff37c724c3564a2223e83ec1b858
f53b500881b394d8392289d51e685709e8fd304f
5996 F20101118_AAAGKS liu_y_Page_129thm.jpg
4a37e45f48f5a254ed42365838948a6c
443854217adca31bc40980ffa8e427c044402d81
F20101118_AAAFIF liu_y_Page_145.tif
bf0d2053d5d66c6e8eb16b1dbb7a6335
c2931a8ef6db2f9c13af39bc43a12ccee94bcea7
F20101118_AAAFHQ liu_y_Page_129.tif
03a869b1cad7e29268d53976655a0e4f
660987c415c4b52dfb87d82c46c5b92923f68d3d
6708 F20101118_AAAGLI liu_y_Page_137thm.jpg
b925a909f9af31af0742626d0b96a41e
9beb9b3591bcdc45f6534ed9269abd489d6c3f0a
18034 F20101118_AAAGKT liu_y_Page_130.QC.jpg
29a460bd7ae7987e6dae0e754968f2b5
9202512e0e24e193ff6d417a14acbb78e73dce9a
F20101118_AAAFIG liu_y_Page_146.tif
cac77306c2a7d7783f0753f31cef5c2e
d0ff82b8e84add3b04af22de2fc914873d12dc41
F20101118_AAAFHR liu_y_Page_130.tif
ea920eb534615e1ce7905f9409c108ed
44fdbcfa7dd043d221af81c41e491f7a63e1f233
17395 F20101118_AAAGLJ liu_y_Page_138.QC.jpg
71c598e62a01d8c0a66f73db41d7c894
d58e553f9905c8f2af02840c682d177b7ba16714
5030 F20101118_AAAGKU liu_y_Page_130thm.jpg
2d844cf6e43a7ee05f6e5c2544bde6cd
db7d4074e48d303cbfb55daccfa5c62fb7193d1b
F20101118_AAAFIH liu_y_Page_147.tif
5c9389d8db4db09dff345465096a13fb
577d0906b5c5cf03e3281ab2bf170b304ebcc5f9
F20101118_AAAFHS liu_y_Page_131.tif
9c7282b074a0c94ea1b9476719da53b6
e8ac0c03bf03263f2ddd868a4779ea33506e2108
5307 F20101118_AAAGLK liu_y_Page_138thm.jpg
ca97e39521e7a2398d6428a0bbe7cae0
afb8c190f828c646d0b5f6d7722cac163eac9c62
19267 F20101118_AAAGKV liu_y_Page_131.QC.jpg
a3ee65e177ee037cef745ec98e8f2cb8
db475b969815ba882a11bfb6f02f9582b90a27fe
F20101118_AAAFII liu_y_Page_148.tif
48df8d444c56bd661b385e761ed1dff4
e752368bb809c365671590c443ea8ad8c53a9ec0
F20101118_AAAFHT liu_y_Page_132.tif
9e654c8eadeaf7459ec8d8d9b17496e5
36a3ae88b54d0630ea6f825f3b74c9330c9b478d
18451 F20101118_AAAGLL liu_y_Page_139.QC.jpg
09715e0114f7310ce2eaa29668554b9e
c42aa08b92be89d97fe0803aac881f59d0c379fb
5364 F20101118_AAAGKW liu_y_Page_131thm.jpg
b6fd7d047f4237d50fe8ecc33420392e
97a6ff912a7d6adc95b774d16ddd3b7c230813fa
F20101118_AAAFIJ liu_y_Page_149.tif
e9e1e9b79b29d0285845b95629d3313e
0dbc3eaef475dfcec2c6edbe9a3cb8ff3c8e7716
F20101118_AAAFHU liu_y_Page_133.tif
ac44a75bd23b5e65b1740daf576b3729
1dd7ccf2367ee2ac07635c8ac77fcad686283ead
24681 F20101118_AAAGMA liu_y_Page_147.QC.jpg
a756d4e8dcfd03edb7fe2d9df9dbe57c
ba6d9376e425ad1446af19312f72015553a72bde
5329 F20101118_AAAGLM liu_y_Page_139thm.jpg
75502b820cfb68ef684a2c0c0b412bf2
f9befe6b6645b4c5b84847ee6b7a2107b7e2497c
24197 F20101118_AAAGKX liu_y_Page_132.QC.jpg
1cee93273713d26db8ad0eb25f8f486b
4215ecf2c2070d40473a7699c556154b4ecce5eb
F20101118_AAAFIK liu_y_Page_150.tif
0f19fe944bdad9af583e95e2a0ef33b9
8f6bd764b321528a66b7b5d4cd19a07c32a59afd
F20101118_AAAFHV liu_y_Page_134.tif
da3f61d6f93d914efe83bef3a07532b3
170216b548689a2d3f000381a085a9abef119ae2
6651 F20101118_AAAGMB liu_y_Page_147thm.jpg
05a277a8f4772f4767668f0f32e3f206
8d8308842a11bbff33746bc92912a73360250610
5458 F20101118_AAAGLN liu_y_Page_140thm.jpg
cb96d5ad3a96984fe05585a0bf6d8652
b51c309014526d672212dace57a9c8b98e72532c
6661 F20101118_AAAGKY liu_y_Page_132thm.jpg
ae57f7699b44cc5a2432364c721ca7a1
6a486ea6009eb8592e18364812adf50910b7702b
F20101118_AAAFIL liu_y_Page_151.tif
b974513a153cab564aeea79d7f3e4b85
85464c6fadff0e48001dc16f0616b122f8dfd2d6
F20101118_AAAFHW liu_y_Page_136.tif
e93c1b22af3aeb2e369e64298e59e7e5
cfb7b850dd4379d46480f7932184d191baad458c
25255 F20101118_AAAGMC liu_y_Page_148.QC.jpg
c498338f257c8bffd77bc7834b03e028
939f40feacc59aea4862c183162a17726d594696
20078 F20101118_AAAGLO liu_y_Page_141.QC.jpg
e89d5cd78faef622002624ee1cca2532
f2f06af28843753b07d8d6381587396d06123a6c
25149 F20101118_AAAGKZ liu_y_Page_133.QC.jpg
c382561f2e359dc3faea6ca6b31b0edb
79aaec93e097531988485ab10990ccfe9bd4e248
F20101118_AAAFIM liu_y_Page_152.tif
942e01944dc1788410de3a008fad8f9f
ecfc36e3b36ae9d2d5393c63749cb95569bd21e7
F20101118_AAAFHX liu_y_Page_137.tif
ab4849a4030a101dcf3d8f830fb88d60
e065fcc0d1ea8b357979fb8503a0367df7904a93
F20101118_AAAFJA liu_y_Page_166.tif
9f524906c8ceabbcec69e86a71d1e9e4
e976cd7b891f6a6e4a22b7e274a99d99435c4bad
7048 F20101118_AAAGMD liu_y_Page_148thm.jpg
d03ecf4513265cb5a9fcb255f1d1d711
d48933d4ae98a668d9c2657e48087fb5d1041479
5603 F20101118_AAAGLP liu_y_Page_141thm.jpg
9e40688ab0c91c137517790632db1c8f
a15ae75313770eba6e94dd33254fdefbe9790211
F20101118_AAAFIN liu_y_Page_153.tif
7d1fd77eadd18ab028a9cc8705b0c5df
6175f413dddd5e4362991982ac58456b24c76c0b
F20101118_AAAFHY liu_y_Page_138.tif
76c42ece621e3c7734e772d660004f6f
6ae5b25d30da0f7b93fcef9507eeee7cbfac6085
F20101118_AAAFJB liu_y_Page_167.tif
dd42170c757c174f60447aadfc511b76
6ab3d431f43108bc1bb118d99b48caf945a779ff
18209 F20101118_AAAGME liu_y_Page_149.QC.jpg
601a8502ba4d1ae16cbbe0f8825404e6
07c5a21c9180af271f7c791de98ead9df3bbd7d1
F20101118_AAAFHZ liu_y_Page_139.tif
02a4e829336b0d52d7254bcef61bf7b2
517018ea2d2bec268cc9257be975f9ba8da0cf94
F20101118_AAAFJC liu_y_Page_168.tif
9e1285addf91c31118f3b851f249653d
accea13f5bf6f22a8390a98f5df4ffd4c0b49ac9
5147 F20101118_AAAGMF liu_y_Page_149thm.jpg
c1400045a5ca0d39a10c806cdf6df61c
474f2a4113dc186cecb9ea243fc82a83c805a210
19281 F20101118_AAAGLQ liu_y_Page_142.QC.jpg
0beca9e9bd4e525c9d84fd235524dd73
0aac6124c77a8d2978e0af01dead52655aa8166a
F20101118_AAAFIO liu_y_Page_154.tif
9e644edf153c48a6d779f3cb0a907b2a
4ea860a12348bf5de8b95ab9424b68f1577622d4
F20101118_AAAFJD liu_y_Page_169.tif
dd87efeb594da9dbb8146185f6cd9cbd
988110e99dd53bca0870e8f621b8dc31e283e0db
26220 F20101118_AAAGMG liu_y_Page_150.QC.jpg
339529fa8ad4b3c0ee6fa5293dc3ec40
3401a73b86c6c188917ec06920541d8b17a328aa
5509 F20101118_AAAGLR liu_y_Page_142thm.jpg
d73938682830be3ba84bcd86cf750f13
72e51d6d668b5341bf6a2625dce5049e981c4df8
F20101118_AAAFIP liu_y_Page_155.tif
863d72f8535dc88d898d52f24ea59161
53fc04bdbf81db564a114c6824deb4d412f061a6
F20101118_AAAFJE liu_y_Page_170.tif
72a77f9d2d1ec5162f239a4ac62676e0
94f5624d806305c3e6046393f9471d7c672e911f
7260 F20101118_AAAGMH liu_y_Page_150thm.jpg
6249af076e478c01821e0352a4d8b2e0
18fdfef12c05b7031259173b57f546cd51690cd2
17679 F20101118_AAAGLS liu_y_Page_143.QC.jpg
9445c5fab6af132253c39dc8cc380932
9c73c9f5a0425921e05ff770a5c73383143f789f
F20101118_AAAFIQ liu_y_Page_156.tif
b7327589f675dccb9a51995a07a020d0
fad727cb822a0a9d9c15a95961e322547ebcaf7e
F20101118_AAAFJF liu_y_Page_171.tif
640418b7a746279877eeeec750f53fcc
2fec32a0c861179fa4fa88d46d0cc986f087d708
20140 F20101118_AAAGMI liu_y_Page_151.QC.jpg
3aadeee25a027a6272bc751e862b1cb0
e861ede0cd0da4f63352f23a72bf9c7494b0f49c
5305 F20101118_AAAGLT liu_y_Page_143thm.jpg
7abdeac9092297166224ba7560cd1c41
a859e4e3bbc529a6f8fbe14613840f20e5935f2b
F20101118_AAAFIR liu_y_Page_157.tif
ba00ea4f90d2394c420be30501883c11
af92db5b14c59a8efd8271eb760c8ab95b961e55
F20101118_AAAFJG liu_y_Page_172.tif
e4be8ffeff2e54f38e7b4969d56b5905
3e519f19ef09f292f0b4af0a9f370df9765366c8
5892 F20101118_AAAGMJ liu_y_Page_151thm.jpg
677e11b9f4b45ee00e95dd8b8f49e767
15b59925c5dca216c6b86746184d01a97a1bf0a5
17727 F20101118_AAAGLU liu_y_Page_144.QC.jpg
63a5a0ddfa8411815352ac4faecb03d5
f353c471c2fecb0796c5632564d114844bec5c52
F20101118_AAAFIS liu_y_Page_158.tif
8870e4f1ba9877903976d03031497e71
664c58c842c173c36e6beb9162669f007d47b8fc
F20101118_AAAFJH liu_y_Page_173.tif
fa93958cefc57edaff3f60245852b182
479624a0e2e95111c101ab0b6a8beeb1769e5d19
25530 F20101118_AAAGMK liu_y_Page_152.QC.jpg
9580263d5975d26fb43dfa671ac74a0f
ebec52a85602d0ef6c685a12a3f3171dcaebb38e
4987 F20101118_AAAGLV liu_y_Page_144thm.jpg
ba123667ac4a224a1e1cc2ae543d6ae3
aecf30ac3c2551db6fdac5f00300f7b7207d21e6
F20101118_AAAFIT liu_y_Page_159.tif
42522b4b35407dce08f4bc22027bada8
4d11ceddbef7e8b1015f8c2660219d107496e5e0
F20101118_AAAFJI liu_y_Page_174.tif
2f4f5e793d50260e4810d5c65d3b9d48
49e4bcd67e4ea292a9d3ef5a39e22114751b1253
6626 F20101118_AAAGML liu_y_Page_152thm.jpg
f0cf0f8a77e8d5701bb46fff27bfc3f6
c4fccbaaa7cd08795d009bbb2c0f3c06a6ae0e32
28512 F20101118_AAAGLW liu_y_Page_145.QC.jpg
b77750e56971910f82ffc564f0ea2f0f
15f08cc3c4ad84d96823d89f9b4c65b3d4ca7275
F20101118_AAAFJJ liu_y_Page_175.tif
7d7d72e389826d176e8f443ff89f5cf2
e872b738dd3e18eb6546d47c12b25757b82c0822
F20101118_AAAFIU liu_y_Page_160.tif
90f185991f99e2094e777aa91c38216c
9275cb924a699c0a4f52902bd7bc0078e8de2efd
4696 F20101118_AAAGNA liu_y_Page_160thm.jpg
99dc29b37541ad00db21dba0bd8f7425
e4a65a212f9eb093ab808394854029a9359c9504
18717 F20101118_AAAGMM liu_y_Page_153.QC.jpg
3bbd150a1e36c8e15cf4007a67aa46f0
f34a794c2fbef4cab8539482b058b5c5da430516
7541 F20101118_AAAGLX liu_y_Page_145thm.jpg
ecfe700e7818894aeadea39e93bbc7dc
87a236a5e381f523474bfa61895d16a3ef804b3f
F20101118_AAAFJK liu_y_Page_176.tif
7980b6e1cb8b52759479f290b8342a35
476e031b4f53f28e601dbe41e4c5067f6016048e
F20101118_AAAFIV liu_y_Page_161.tif
bea9c9d2be52ce3f5213a27530600a40
5a0b3540b1bf607ce09c9acf30de779fbdacd011
14616 F20101118_AAAGNB liu_y_Page_161.QC.jpg
230ae87d20172f5d17d22e112426d71d
413b63a92350cb98ad578dfc9036a3f5cfac523c
5574 F20101118_AAAGMN liu_y_Page_153thm.jpg
1065b4b37940d7e12b16a7e39d9a47e8
166d84ecf65d9f07639a7b76c737dc959dd4ab9e
24888 F20101118_AAAGLY liu_y_Page_146.QC.jpg
c52d10aebe226a246e6dd8c60b98f917
a549ba39b58bdd3599fc0561ea7ce774c1aa7786
F20101118_AAAFJL liu_y_Page_177.tif
b51d16e012f21abb1db373843e4d679d
901139dca722f3c754c2e780f24bf5b2c860aa94
F20101118_AAAFIW liu_y_Page_162.tif
2eb368bcd2936303d00e6a07d61ea9bf
9245f4859ee3766d1865084b31df2822f1e4ad89
4547 F20101118_AAAGNC liu_y_Page_161thm.jpg
24f014a4a033051c5d7af95517f78085
54784398bb500624f7bd38dfb21d6c6eef775110
12004 F20101118_AAAGMO liu_y_Page_154.QC.jpg
f2c424fef4927272b11e50665044945c
56c4df83ffd08610b421e29db319888a2dfe989a
6670 F20101118_AAAGLZ liu_y_Page_146thm.jpg
5ac2a4478fb81ee95c641bd77375bd04
f66fefde513cedfafca48bd774e9b82b2887581b
F20101118_AAAFKA liu_y_Page_192.tif
868e0e01d60fb3fb3137886758950afd
841889f7a63d28cb70c5aa513e3f88ef8cebc890
F20101118_AAAFJM liu_y_Page_178.tif
3ccfa299e98d1944b6fb76327a9e37a3
e3c41d19348737f6c21bbd8c5b5ec19577735737
F20101118_AAAFIX liu_y_Page_163.tif
710d9056a25a3dbabb39fd63fbe4dc78
8acdedd18ea31e936a5dd3220c2e2cbe6d96a100
25358 F20101118_AAAGND liu_y_Page_162.QC.jpg
1ced18613344184e099d928b72f5439f
3b3ddbe9775a70e87174fb0495d41285e5bf76d3
4258 F20101118_AAAGMP liu_y_Page_154thm.jpg
b5d0b6c3cbb7fa0ab1c014b86074abfd
19dafbd3517b07c96530a0d6239223e23598a34f
F20101118_AAAFKB liu_y_Page_193.tif
f7ddb0687a7c3aad1891e96f374feda8
a385e13133b635ded0057528b5287d8f157bc6f8
F20101118_AAAFJN liu_y_Page_179.tif
9a6023fdea9e4077072b96b61989a021
f3d432f495aebea69ae95cd8d86f805c1e3c9203
F20101118_AAAFIY liu_y_Page_164.tif
2ba11de80bd42427e227d381529d4ef3
43792aa9da846aed9cc55215628a2f20d301d738
7272 F20101118_AAAGNE liu_y_Page_162thm.jpg
cff5597d9c69c9134a80d627b7494c65
6fe5c254d8ba27de8747fa96afc3de4997d86acf
20751 F20101118_AAAGMQ liu_y_Page_155.QC.jpg
f854d800256c86c27f7ffdd0975c52c0
e421471f361c6cdc4cc48fe2a2807c0a8514dcc6
F20101118_AAAFKC liu_y_Page_194.tif
587d3fb6e8b42def0bb0485426cd18e3
dff4cf904755ee3fcdae069a30fde6f2b78feeda
F20101118_AAAFJO liu_y_Page_180.tif
8e304dca6472c28e090c0c00bb3a8b5f
54ff29f469b1502ed3f3b314d35b7f02f8575b13
F20101118_AAAFIZ liu_y_Page_165.tif
bb72076078f88cc31371fcdf22eac111
cf5f160b1f057d496e9e27deae0aecb18fa4eb10
18808 F20101118_AAAGNF liu_y_Page_163.QC.jpg
295719b8bb45227c6c9ef6b76bfc4d39
340391a72c01b70f18b784d4ebf0273b4bb852ff
F20101118_AAAFKD liu_y_Page_195.tif
d11555f37ca8a470914c916a44496b77
866a38fc36c8cd0c41f0f56d35f03ebc6b3d5dae
5451 F20101118_AAAGNG liu_y_Page_163thm.jpg
e19887b498bf2b5af2fba8177e99385d
acc1efef1382afcb08b4473a55dc0bb0e5eaa67e
25444 F20101118_AAAGMR liu_y_Page_156.QC.jpg
988096a63c061e236b292328ff738fac
89ed1884dca1fd8af46e98d4fd7c17383f6d5238
F20101118_AAAFKE liu_y_Page_196.tif
de420cff3209c02ee86f81f94555bd9c
0314d5aca53c3bc91158928d80590f400d9b9933
F20101118_AAAFJP liu_y_Page_181.tif
e5fd7a4d04299748f8ddbf2801fa44fb
c0ea07f7da8471530d5355f1d6e0528d26ce40c2
23512 F20101118_AAAGNH liu_y_Page_164.QC.jpg
19a93028246a579c327cdeabf3a9bf21
5ee6373791ac50df10a65a713dfc7306eca632eb
7245 F20101118_AAAGMS liu_y_Page_156thm.jpg
a1cec49e59295b708e555971a83d912c
925302363e1ac482bbd3e3a0c413ecc100cc6e85
F20101118_AAAFKF liu_y_Page_197.tif
cfd55250eef49320054095e3a140e2b3
131456f98b63bb6db4b24cdc7e84cd684c2092ae
F20101118_AAAFJQ liu_y_Page_182.tif
510b7bc95ee03b5cd8ce30733887537a
13748697d984c3277478e0df01a0d36e72706478
6156 F20101118_AAAGNI liu_y_Page_164thm.jpg
06b968401b8c42f5ce612b6c1b2e2364
a565e4abcc48ba4367e9e8b1d827978a4e962b8a
16360 F20101118_AAAGMT liu_y_Page_157.QC.jpg
2fd7717bd687a14f5ad7f4ed8c07d9a4
a9693124d56571adc6d16bdfad7d6de20b8baa78
F20101118_AAAFKG liu_y_Page_198.tif
022ec2a89871f812cd7781556954c0d3
acd9a281196badbdd37a77b17ddc9c238c33f1a2
F20101118_AAAFJR liu_y_Page_183.tif
ff3a5908821e1f877973cb2d9deb86ad
31a9aa467401178cc1ccf7f765aaa6c61ac2aff9
18067 F20101118_AAAGNJ liu_y_Page_165.QC.jpg
c2db4ec6e45d747d2e00fa4855702e01
8306398917342591ef559131f146353c48619e42
4880 F20101118_AAAGMU liu_y_Page_157thm.jpg
e0c46bb53e78cd2890e166132e80a397
7a14983d99a9fdb8f1b7cff5765ee04971a65562
F20101118_AAAFKH liu_y_Page_199.tif
2e95b9a17d343acc159762a264875230
c12c27bbe0a4893e828ce5ea3f9f4a0cc2f461d6
F20101118_AAAFJS liu_y_Page_184.tif
edf94c83f99d44f78c12abd5c3983c25
42bc5319c2db6b0f95ee645a23c1193f16ef65b0
5025 F20101118_AAAGNK liu_y_Page_165thm.jpg
a67a131ae3afa0201f6484a3926a9cfd
c86b2572ae40e5f11817dd57984eb87d5c67506b
13175 F20101118_AAAGMV liu_y_Page_158.QC.jpg
6390e731edb96e2cb7f85d7966d9e9d6
fadbbe86fc2191b936c5d4830ba657f824f20f13
F20101118_AAAFKI liu_y_Page_200.tif
5d07fe74d0d68b63a0e9d6e1a631ce62
f6096a3fd90896033e8f1789f1b4ff7a26206740
F20101118_AAAFJT liu_y_Page_185.tif
ad6acadefc79565105c940c3dbe2a242
0941e5be187cc25db80acb355dea91d0e7c9ad0c
23584 F20101118_AAAGNL liu_y_Page_166.QC.jpg
e6bb08a2d16a1d700eba1b4d9a498d28
fea06139cbec48e9b269d9f91038ccf562680d71
4052 F20101118_AAAGMW liu_y_Page_158thm.jpg
1950186e846ea23c406a9fc4a1eca75d
886a2c2d81e98b9e0062942cd9d33e812c78f7aa
F20101118_AAAFKJ liu_y_Page_201.tif
6d20611ee61f84939a8ef26448bc83e3
1e44273d9646668b9ff1eadd66b45369cbd42eb8
F20101118_AAAFJU liu_y_Page_186.tif
b26534384257afe9ce7ad0b54080e8ce
c68d460da026129215db1c4fc511a3ad20eec1ef
5927 F20101118_AAAGOA liu_y_Page_173thm.jpg
9184061932a02b9f7f8d60693d0cc8a0
3a1c9772f73b2e578d6ef022f7a1a90405f1b389
6944 F20101118_AAAGNM liu_y_Page_166thm.jpg
f5b5d764a2ed5c2a8595766b93c378c7
56fcfa6bb68bd0adb3dac660e00debc3b17f1266
16570 F20101118_AAAGMX liu_y_Page_159.QC.jpg
940279b2ee3232bc85b27da323955156
0206a70fbe6e87209b857c0605d1348361ba391d
F20101118_AAAFKK liu_y_Page_202.tif
4db9b01461a898572f26aa6d0b41248c
3973413de50e9a136f5bb33aea9ec62437c34ecf
F20101118_AAAFJV liu_y_Page_187.tif
75424b9611974e2cd9f998931e40d592
457ae126eff63c0af35a08b3b79501cdd721004a
24985 F20101118_AAAGOB liu_y_Page_174.QC.jpg
06c7e3d0947db1a44eca7104d7f0148b
082cebca30a9564d1ee60c60574fa25d2e40aad2
11393 F20101118_AAAGNN liu_y_Page_167.QC.jpg
6fc1a705dbd88feff6dca4d38176657d
f6c015c61ed42f926ab5361ab2675734ae022492
4381 F20101118_AAAGMY liu_y_Page_159thm.jpg
f2b6875760a539d42a2217c5909365f2
a39e7f24b9e33f1dcc9d867d4c0f5375426fa9c0
F20101118_AAAFKL liu_y_Page_203.tif
0dd3f2acfc629b95a6b90f304b6b5611
7a080b6926de41ec4db8fd46e882c70fb3ba79ca
F20101118_AAAFJW liu_y_Page_188.tif
cbd0fad662b3933a566d6c3d9d21f717
a15bcb5fe2fb326e74c508221ceccb7f3d585869
6487 F20101118_AAAGOC liu_y_Page_174thm.jpg
53fc8e478bce3e1f67a25d39d9d410ea
f4a37258541045c22cdc270ebf9def94ed6201df
3830 F20101118_AAAGNO liu_y_Page_167thm.jpg
4b3f2c8c8506488bcf0c1e85ffab96ce
e8144b14b7ebc378abf368bd85a84e7cfeae5148
15077 F20101118_AAAGMZ liu_y_Page_160.QC.jpg
64d7f93aeb4fb292dd9b6b8efd3ecc90
1a433e91f175a458f03a761d343b8e571a6f770c
F20101118_AAAFKM liu_y_Page_204.tif
865fa7c2e6ec3d6b0ed34535d10d7831
4d5d19858da74fe5ae284c22a631788eed528004
F20101118_AAAFJX liu_y_Page_189.tif
793ff7eea8d183c501ce4036b2c2cfbe
c929292063209e31d597f15afc5713da512fad5a
8433504 F20101118_AAAFLA liu_y_Page_003a.tif
563a3d25f8542eb5567c703d27dc0f1b
efde7903f7035cd5df50b89251e45ec0c59960cb
13494 F20101118_AAAGOD liu_y_Page_175.QC.jpg
0203de9dbd5b4841321305ade72ef739
3915434dbcba38773ee5a8ef39bfad07839fa1cb
18439 F20101118_AAAGNP liu_y_Page_168.QC.jpg
66bd81db4c2296f0902493af5de0602b
1e89e699eb7b71856b97ac4e544977aec2c18056
F20101118_AAAFKN liu_y_Page_205.tif
680a61213392c764505ef26c1e8c400b
cb5d0a2bec90e4249e4962c8bf8c4f37f231e96c
F20101118_AAAFJY liu_y_Page_190.tif
1d3fe836df79b1e0e782cc2f5529e0af
68168e49b89d2626aa7d16c1432ddd9c3ed13626
7665 F20101118_AAAFLB liu_y_Page_001.pro
44f3bb89c06b619e5f222b9d1b661659
9f396fd6e5ff3243dfbe1880e69d8338fde2327d
4557 F20101118_AAAGOE liu_y_Page_175thm.jpg
a053ed1d699709a8ffd6a99d5a40f438
824f01ad09bdeb34c24b97f13be2dcd6185bcbff
5682 F20101118_AAAGNQ liu_y_Page_168thm.jpg
152dc8f069ae19c22a0d15c041f65688
a493ccbaf4d55a936f981390df4e38fe0b4dd07f
F20101118_AAAFKO liu_y_Page_206.tif
becb4700cc603f8656541244ca891705
258b0044aa2f5dd29ccaa9622a6cdf5dde8dbf74
F20101118_AAAFJZ liu_y_Page_191.tif
3effbd7e1037e50c156ffa4cb4487621
f8090ec57a68c9892010877cf20f3ce88e7dae21
728 F20101118_AAAFLC liu_y_Page_002.pro
80e5514358a006eef8a8f0e5edabfa22
8853df8225f60dee2533766b70fcc29848efdb9b
14162 F20101118_AAAGOF liu_y_Page_176.QC.jpg
78445624f4dcf01f01d7f2b8fc106deb
bba6bbb193f5abcb1792a52bdbcce0c84cfd2fac
18217 F20101118_AAAGNR liu_y_Page_169.QC.jpg
1197fc0e2368d0d5f8cbc9ba3a58f4f4
90ec82127815d35ffe988db9cfed067ce83c4cb6
F20101118_AAAFKP liu_y_Page_207.tif
4187728e68307f0d74df919cbb9b6a21
e522b7d131307c779fb3b7ac5e180e33b78af23a
7412 F20101118_AAAFLD liu_y_Page_003.pro
daa67c59732b7c0e17586baaa15c16e7
78926f6eb988e68122524427979c82a2efe93fae
4876 F20101118_AAAGOG liu_y_Page_176thm.jpg
fae1584bed96e80479fe70093fe966d4
aa4b0033be4cd9749860d38a0feed7fa64a61da7
50596 F20101118_AAAFLE liu_y_Page_004.pro
a3b564021be6fb0f662bdd0afacc89bf
3fd628220af58fc551a96d4d50804d14cf559345
19184 F20101118_AAAGOH liu_y_Page_177.QC.jpg
68b650d7b162d6f59ad8f11376ef1a7f
b8d06642d64908a3413c5afb1607cfedde4599f1
5533 F20101118_AAAGNS liu_y_Page_169thm.jpg
13d67ccbfed085bb953f7b37ae674f99
9d40d25abd2e22eaa6e4a25350adb2111e032a7a
F20101118_AAAFKQ liu_y_Page_208.tif
d69489b9a85a00ff15b6693c1af2f576
8a255a5c72ac4b6f895cec371febbdffff450d92
97051 F20101118_AAAFLF liu_y_Page_005.pro
4498d237b649358d5f9e9035365e37db
cdb496a543bb0722ca6bb3ce0a0d7afa18fc749d
5240 F20101118_AAAGOI liu_y_Page_177thm.jpg
8bad24c506b5045ecb0f900ad8eabf9c
99026ca1ea5064618627117085a092ce804b06cc
19209 F20101118_AAAGNT liu_y_Page_170.QC.jpg
4dde3cbdacb0066846c7a40a00d5f8c7
cb00a4295ac56074277a342bb25b3f2add92ce51
F20101118_AAAFKR liu_y_Page_209.tif
7bce5e5a71ad8046da1a197ec25ab196
45432665447bd79ae111e071879f48e6210030ac
117870 F20101118_AAAFLG liu_y_Page_006.pro
57c930fe6d333bd85017f315bf6ed4b7
9e0cdfa9cfc402aea14bdfd544739b3c1d899eac
17531 F20101118_AAAGOJ liu_y_Page_178.QC.jpg
94df357391ba006dfa6aa6e5f9ffb82c
1c20099678ce1ddd65e49b8d49b0042cae5eab6c
F20101118_AAAGNU liu_y_Page_170thm.jpg
be99b65236397fcb66a845650958db8c
a4dbc467c7f10bee09209c06eb281ca1d5b31aad
F20101118_AAAFKS liu_y_Page_210.tif
b9fc921e47d6202213ed071cd7b454ab
d0818c1c700f4b096f90560efd06bbc7364bbdc5
115755 F20101118_AAAFLH liu_y_Page_007.pro
4d558be643f0fd812357fb7f818c2e5a
8cbc750eba1f278d1320272b8854d5828437cbc4
5482 F20101118_AAAGOK liu_y_Page_178thm.jpg
8c35cc0ffd0c57791b7705c3230a9e62
9948581b4f73f93d71f6645b4b6de609c89392d9
22895 F20101118_AAAGNV liu_y_Page_171.QC.jpg
525b9dca98a48e89b27fd568f2072d12
7dc49378065a715b11e4897cd2749ae2dd144d3a
F20101118_AAAFKT liu_y_Page_211.tif
6478b42776e38cbbc7ab3b3f8717f272
5e5e6f87d4dd06a317a1579d0043cfa8982fd6dd
39918 F20101118_AAAFLI liu_y_Page_008.pro
b58c50e1ac05f68fee605c9d3927aa70
77351eaa2e43bb985f5fe20605c0475f9643d2a7
16889 F20101118_AAAGOL liu_y_Page_179.QC.jpg
43ea983eda135fedb2a430f93a31d657
596f21c5cc492fd84faa3bf17b2089a394115538
6158 F20101118_AAAGNW liu_y_Page_171thm.jpg
ad47947fa9ff84181b185dba983138bc
0a7fa5b308fa286b9224d682b089ade7fc20cf8b
F20101118_AAAFKU liu_y_Page_212.tif
6632530b6983da0b226bf69f221453fb
1185dfb79aa23e412bd8abd3f885fafe4ef350eb
68243 F20101118_AAAFLJ liu_y_Page_009.pro
a527c299a1c68a12bda8953a1c18cab7
7ef7f5695a97bd4e96b347a55fc13911fc2ade0d
3164 F20101118_AAAGPA liu_y_Page_186thm.jpg
bbc5d0ac893d2bffe7483ddaf54cc3dc
b4af1f4107aa84557dd1b4e184e73aee589051d1
5206 F20101118_AAAGOM liu_y_Page_179thm.jpg
7a1148d3f299cc1cac8646593f0acc9b
7ba33b34f81900bfe0822abe9e970d5d5f2ac424
19430 F20101118_AAAGNX liu_y_Page_172.QC.jpg
ca7158bf20529055ceea1c2b3518adf3
7cba50434af159826f5edb905359eb088e7626ff
F20101118_AAAFKV liu_y_Page_213.tif
0cdd46f5fef9d480b1769d79fd928d37
3d75a6623b3d4fdd6be7fb74d12e393f2c803c8a
48041 F20101118_AAAFLK liu_y_Page_010.pro
4536afa58377bfb48a38664cc963136a
26a76fbaa4919aa24560733d8e9c8800f4d77a2e
23026 F20101118_AAAGPB liu_y_Page_187.QC.jpg
d42aa362c31afb1d62580f91e3999c6a
04461090af9f6f0e8a302f4a9496c40a69c34be2
16863 F20101118_AAAGON liu_y_Page_180.QC.jpg
0dd6cc67b27d14ecff8dc2351caabdb6
35ead726317be1ab3541079e561f8b49ef9d28d5
5419 F20101118_AAAGNY liu_y_Page_172thm.jpg
ee22c7ad6c2663d2386a641323e87d56
5abb5b8d9f7869d31f945296c762e8a5bf114e97
F20101118_AAAFKW liu_y_Page_214.tif
d29737d4edc474bc4aec0999cd45cee7
123b497102c2da4a65e1435c108c380c83bc4294
67300 F20101118_AAAFLL liu_y_Page_011.pro
42c24a85bf6ab5b8cfda0920851a69ff
9417cdab2f95292378980194d4147952fd19f393
6489 F20101118_AAAGPC liu_y_Page_187thm.jpg
52e1c445c9132e2a46025e279556f9f2
82f40ab17236ae3a9836d1172c064da8fa73970d
5273 F20101118_AAAGOO liu_y_Page_180thm.jpg
281424fa4267401960d6e090c8be9b1f
45e1422daf8a53cc2ffabec1035513b460c5ed9c
20049 F20101118_AAAGNZ liu_y_Page_173.QC.jpg
5f0ea3f725e353aa85d9e462f99e63dd
e02737c1e518af44c01b9563d48c3fcd89a9abe7
F20101118_AAAFKX liu_y_Page_215.tif
f865c62d0a0407e2fc71e7258de41510
dedf06b59daea65c8a19ff169173c1edb03ae181
38094 F20101118_AAAFMA liu_y_Page_026.pro
327e23d2a7311d4757fd69f8b54dc759
29c43cb42166565006d554f8e86e757265bdb405
68754 F20101118_AAAFLM liu_y_Page_012.pro
b9c5fe7d3542b875b376d7255a66ca1a
3ae078a2cdc9ddfa976d87f742b0b9e4b3c3c99d
20005 F20101118_AAAGPD liu_y_Page_188.QC.jpg
16cbe8144bdd7c2f5127c4488d3b7126
6e540d1a50a010457c7a9b474ec11973d63c1297
13376 F20101118_AAAGOP liu_y_Page_181.QC.jpg
7e74273bc4c0d3a13236c0ba4ce24864
798c1804cb6f8aa8f888e1b411853704cf3627f7
F20101118_AAAFKY liu_y_Page_216.tif
582a3a4e9ae48dd36a6e4a1a07ef84c0
bd346b90db61718c25a4dd28bf421c1da57784dd
53618 F20101118_AAAFMB liu_y_Page_027.pro
212a12853b855d9a4350d1c9f1b56c18
69a591156b6aff0318685192c1f619eb217ef4c4
71516 F20101118_AAAFLN liu_y_Page_013.pro
c30be765f928c38d62a95c46604fb55d
3dc02e6d8e6006c1069d8e1db31510ad33d141bd
5513 F20101118_AAAGPE liu_y_Page_188thm.jpg
2f53824c0581ca5a5db1f607be9d0fea
cacde174c33130979b75320f27ffcb63bfc1642c
4070 F20101118_AAAGOQ liu_y_Page_181thm.jpg
d95b4047dd7c26beffefec7500d25589
baed4b8024b4dd9b307484b8bfd55558a0d58230
F20101118_AAAFKZ liu_y_Page_217.tif
72bbbb72fb05e73206a24f7cd8cc7dd6
5b449c5b62ed03fe1558bcc25f3afe78b5482821
36340 F20101118_AAAFMC liu_y_Page_028.pro
3bec7883e3eb8e2037acd20d4edfb8f1
68d94f15294b4bec8ddf441fc3ec125a5aafebd5
74661 F20101118_AAAFLO liu_y_Page_014.pro
1dd2cb6583b4e03a2cf6e4461d43eab6
ea41c6c9099ef586692d61ffa5db4b4ce7ef255b
25604 F20101118_AAAGPF liu_y_Page_189.QC.jpg
1371ba5a9c8f45e683b1a34cca06bc71
b1bced01eff9e690418c7e39a1026ffa5958a3f6
14588 F20101118_AAAGOR liu_y_Page_182.QC.jpg
88670487175751d8326c66a51b34f3ea
be00225a5ffa06cefe47bcfc64cfc2452e57d1b5
50572 F20101118_AAAFMD liu_y_Page_029.pro
a770c97f70e20738f61f16815db0d8ae
67660c5729951ff3e9fc81165243e5cffdad29fe
16195 F20101118_AAAFLP liu_y_Page_015.pro
2e750702a784d9226a1b5afa6a608196
ed60ecc20815ef2a22a3be91bc38edf989faf968
6789 F20101118_AAAGPG liu_y_Page_189thm.jpg
8bdee897f59b78bdda6fd369d04eba58
ac6a6a6db8fc3371d0da22984ccc88b830c9b024
4754 F20101118_AAAGOS liu_y_Page_182thm.jpg
d6a4b4c880a5ccb187a2464c30acb058
fcae444afb9e1ffd01fcb18276e999174cc79bc7
55272 F20101118_AAAFME liu_y_Page_030.pro
260ca111f211bfc39a8b0432f829a593
303fa2a1c94be736882157057674e272e89c0ece
46859 F20101118_AAAFLQ liu_y_Page_016.pro
cc5d3364b15d74c4aa2d9a876bae1598
bd7be72d48fbc112e0dee288b24a48107ed2ac80
25134 F20101118_AAAGPH liu_y_Page_190.QC.jpg
8271be7b2fe3f393ec520dc1b92c69f3
079f828a582e394e5348ad082a7a4b57fcf6af33
53999 F20101118_AAAFMF liu_y_Page_031.pro
45b9d871f5b8f1cc5d7374bae00d68d3
7d44c17ff29c7375001c48e5a7816cb4942e3d7b
7015 F20101118_AAAGPI liu_y_Page_190thm.jpg
2902f99222072cc6a6ad140b9144cc86
f5278394d7d78229727573b7835e892a4cea8349
15115 F20101118_AAAGOT liu_y_Page_183.QC.jpg
1d1673261e1cf280ffbd653500283605
c6d523e3791ccdcb6233f10bbe2fb530c128b0ec
38961 F20101118_AAAFMG liu_y_Page_032.pro
dfbba837a5c28591f39c92b6fca39425
0e0dfeba7ff64d7b5d1d36a9117ee923e0629b57
36624 F20101118_AAAFLR liu_y_Page_017.pro
3d35ca9d10ea3ae8c466c85159a898b1
7b381ce83a90c73a67885acba5ed971701cae068
19653 F20101118_AAAGPJ liu_y_Page_191.QC.jpg
85ce2d46f865c7bdb1934f648e2d80a2
ce0f0e9dc4feb80da9f9217468a146d0959a33c4
4786 F20101118_AAAGOU liu_y_Page_183thm.jpg
dee11f83d66c002254aada97be6b726c
891f61cd99cd1083c6cfec67bc044462faf77585
24936 F20101118_AAAFMH liu_y_Page_033.pro
1fa63c0abd018d43a18046c3c45c00ec
3d9318203c04db59638a6f816ff0573bc8d0f805
52303 F20101118_AAAFLS liu_y_Page_018.pro
4f3a4d8a831a3d3165ad88a38d806150
dd023742475a50a70d06adc0964a82f59c387330
5500 F20101118_AAAGPK liu_y_Page_191thm.jpg
a365a0cdca871e18ccf75b49058ba9fd
093bb6f61731c05f3254ab1f39bf15a93cba4c90
18992 F20101118_AAAGOV liu_y_Page_184.QC.jpg
4b44c547fb9c8e1cdbccffde7c3f70f3
44e224ca65484aaca719c346761ffec6e31a5c9f
36524 F20101118_AAAFMI liu_y_Page_034.pro
761ed7a0f24bd155eeeccd85126cc202
b43dcb0248711d7513c11e960b41c982dbcad95b
54848 F20101118_AAAFLT liu_y_Page_019.pro
b0db1b424b486487aea7f728ad2915eb
0b71e01ec8eecc178ca3dbf455a3e59596206827
3859 F20101118_AAAGPL liu_y_Page_192.QC.jpg
d88b72fc8f7669e56d8ab9982740e0b7
79d92e72f993f59dbb6bae2d444016662f2e753e
5294 F20101118_AAAGOW liu_y_Page_184thm.jpg
c67acbdc69408c8870c3c71bac494734
917c2ade5b5faebb791898f1b6fddba4f190c283
55187 F20101118_AAAFMJ liu_y_Page_035.pro
ce2fdfe99f394e9e4f1b5f0738c3e622
7146c74741ceed2c1df74b66740a12bd43f03669
53715 F20101118_AAAFLU liu_y_Page_020.pro
ca88b743434897548f30e5c5a930e238
eb239429e6031abd8fc47e69b6dd0834db16f2fc
4249 F20101118_AAAGQA liu_y_Page_199thm.jpg
f61604b1f9e848be514abba56ab67645
dfafa3e915f95ef5893f333475a077222b4514e2
1438 F20101118_AAAGPM liu_y_Page_192thm.jpg
4ddca0b11644e4d6a07a596f12118e74
ab4a0c91bee6bf9a8dd7769e8c5fcc9f144c65fb
F20101118_AAAGOX liu_y_Page_185.QC.jpg
f639b78c52255a7aca9404e5eea50049
26a80b2de8c777f009232e2cf1c04cb71710c60b
41538 F20101118_AAAFMK liu_y_Page_036.pro
d13cddb5c86e82ed55bf9af31ec5e1f3
4f768f749518c98b30236a39fbdee92e0d503a50
36791 F20101118_AAAFLV liu_y_Page_021.pro
9523396351e483faec81f35014216b74
6cc607f47b1988d4549673de572cc66c2fcf4319
15507 F20101118_AAAGQB liu_y_Page_200.QC.jpg
1ec0d1cbb79575bf5d6bd2f4c95651ec
50de1d848fa4ab37eb19cf4f5e97321a7e6f732f
11161 F20101118_AAAGPN liu_y_Page_193.QC.jpg
5f0296723694d5d9602eb98fa4bdbc2e
f8f7c8e5e01b173db8afe33c968d8fc203fc272a
6860 F20101118_AAAGOY liu_y_Page_185thm.jpg
4df9416a8b8651d20cd5a2007d168633
543673b36cbfa1ac4b726842b47e592ab27489da
53502 F20101118_AAAFML liu_y_Page_037.pro
05acaf481c60b901ce1f4c34c014f6c4
4878f30a9a6f480c93e8f03246cc79156e8d524d
46245 F20101118_AAAFLW liu_y_Page_022.pro
1d853c82492b5ff0d290a9cdfa56053c
dce471886843051589b2bb6034a534fa0e1813c9
4315 F20101118_AAAGQC liu_y_Page_200thm.jpg
09d02ccf062bd5bbe0eba95f5c8ab22c
366237239aeeab85ab4bd5f20ec1c2ada5b36518
2988 F20101118_AAAGPO liu_y_Page_193thm.jpg
745a507393bde03ce304c959d74ab474
c2bf23d6caeb1ad7189c74cea1106124cf354529
10044 F20101118_AAAGOZ liu_y_Page_186.QC.jpg
ae0231a5bcb9d3142158cbbfc0d6b831
91c05508aed65042567206bc61ba9c0d73108085
14052 F20101118_AAAFNA liu_y_Page_054.pro
3d23c172581aee4ee608a0d613ffad6b
0435139f52363f12cabf7cec490a9977ef78d9d2
56452 F20101118_AAAFMM liu_y_Page_038.pro
c525832e48913043dd015f6972eb059e
b0b757873b8e9b26b76e7fb7ba42aa97c3f32fdf
56232 F20101118_AAAFLX liu_y_Page_023.pro
59580a7619fb31c6ff79b82953812b48
040b76e8dd841a131e171c69568436de108e23ed
15167 F20101118_AAAGQD liu_y_Page_201.QC.jpg
54b1e2c7680268c1b6bb93cfcf67b95e
f23996c27495d090b7b063b9469904f82ddc8547
9146 F20101118_AAAGPP liu_y_Page_194.QC.jpg
501ca1a6b8e7c7cdbc17491a5ad5d402
39c0a270e2c198094c84b9ca6f950355e276708e
38461 F20101118_AAAFNB liu_y_Page_055.pro
d359d0ff61624264f97d330e0d5d9b17
4c6d41442f8b79750c30d57d581966c1f5dab304
49408 F20101118_AAAFMN liu_y_Page_039.pro
3d963203d58c907903ee87a7c00ff17f
e7f375524c1a33ca10bdd3c106ccca40d8436cae
52927 F20101118_AAAFLY liu_y_Page_024.pro
0dac2d5716f9ce15922f5ba9a2cda470
fcd0b1f59f5113d90da19e65107ec584c1ba1588
4074 F20101118_AAAGQE liu_y_Page_201thm.jpg
fa7635264e52dcf73ce1669adf856c92
abf99615fa7cba74ab74dacb3e3a69da869a950d
2755 F20101118_AAAGPQ liu_y_Page_194thm.jpg
1840653d877340768e3258f385c570fc
7c8c7e2b559abe8a2f1993abe83b668296339348
1404 F20101118_AAAFNC liu_y_Page_056.pro
7578674d93978fb3295322997728f3a0
cbcb9310b81b5dc10353bf361e91f7be82fa44c4
52376 F20101118_AAAFMO liu_y_Page_040.pro
40a388f3e164cd7f304a15be11b27896
a745b951cf0453c20857a593afc6987799d32744
48685 F20101118_AAAFLZ liu_y_Page_025.pro
8d6311c21cabf357938d3c0643558573
cba94ead61461812472d2f79a8f512d2317f63fe
15545 F20101118_AAAGQF liu_y_Page_202.QC.jpg
6e0a49bd19d2662fbd589c4a561b95a3
2e04a0b308024abf84e0edea93274eacb459e5c0
11952 F20101118_AAAGPR liu_y_Page_195.QC.jpg
c47902719e7e8b6164b2ba488695fe87
b2cef776d977da7e11182e8e482cf8ad5920a9c1
48069 F20101118_AAAFND liu_y_Page_057.pro
b110861395005df558b678d792b6093c
f584aff6a1611a82123feaaf33a4bd04edc2c695
56501 F20101118_AAAFMP liu_y_Page_041.pro
ac6612ee92cee85477817b0c4c5054b3
bed0d15d261eab40eaad43484ad12bc11c70d14e
4099 F20101118_AAAGQG liu_y_Page_202thm.jpg
4b22cde99530521788596f631d533b99
348d2736825f42d727667ddffeb8cdae4d0363ab
3403 F20101118_AAAGPS liu_y_Page_195thm.jpg
277c79b92e49d136204c6b129fc22bc9
871110e2314518d18a268cbca094fcf784e34fef
50936 F20101118_AAAFNE liu_y_Page_058.pro
59f1014685cc9d55b22b2c5810ca06bf
cf116963fd0e2e85930541038b8f165d6c6d1d5e
46982 F20101118_AAAFMQ liu_y_Page_042.pro
e79672deebdcf7de1e06e4914e6a516e
270b6c0fd62fea3ae818a010214649876595e5e7
15267 F20101118_AAAGQH liu_y_Page_203.QC.jpg
60ac049bf9efd72fe5c6d50e75eacf32
041d259e4b530ad08b8ec6b87015040501bb2bf3
9276 F20101118_AAAGPT liu_y_Page_196.QC.jpg
88c85584ad087aeaf3ce927aca238554
4806892ca3c7ca3755bbd7c64604fefaad63dd44
65768 F20101118_AAAFNF liu_y_Page_059.pro
3673d4361d2684362d846c53771d6ec3
0190466f6da939a721cb7eed7f2f1844d896252d
22082 F20101118_AAAFMR liu_y_Page_043.pro
14907ef2c8dac2fc017ceccb252a8c3b
6283b13ecf4da9cc7862065ba6be9e0da0d0d96c
4215 F20101118_AAAGQI liu_y_Page_203thm.jpg
c244a43c4706fd6a6746c09a1ed3e063
56ff6623af020d4e234dcad6272fc27cca7da378
40765 F20101118_AAAFNG liu_y_Page_060.pro
d560b068843dc67ba267b78359e00cd0
9fa22aa3eaf852829bfb5696d2fb638ec86ffa5e
15171 F20101118_AAAGQJ liu_y_Page_204.QC.jpg
2e6de553de6dde7738dc5ccb943b7d80
83e719eb57007bcd099a468bdc66055904df4429
2737 F20101118_AAAGPU liu_y_Page_196thm.jpg
f314ac045219f26d290086eae660c1de
a8352e924db7fc9e95395889633b0c5000d72a25
42696 F20101118_AAAFNH liu_y_Page_061.pro
dfdfd1ffbccbe8c45c34f6318464fa18
300ec6d250d95b4a8dd739087fad2a3625136de6
34328 F20101118_AAAFMS liu_y_Page_044.pro
9d200fa1f2e4c31e5734cd34bf8e9c45
95c487c6b4a97fccf3ffb066541ebab4d510acf0
4169 F20101118_AAAGQK liu_y_Page_204thm.jpg
30eef8d41acbe505c54d60722986b232
be62a710dc09df1e3f5cc87fd2542d2da194f09c
10295 F20101118_AAAGPV liu_y_Page_197.QC.jpg
2654793d171faee1b7e3b342fa858c73
03a871a0dadb48fcc0f78affe5311f6e710fb847
12630 F20101118_AAAFNI liu_y_Page_062.pro
d3f54759863726b78838e5c00cd86d09
64423a22c791f5a0c92a5776c6997eba35fe9f51
42126 F20101118_AAAFMT liu_y_Page_046.pro
fd100817f569c7871ce9bd5b17216b14
084cb52f7c4a7ff71ff6661c3037c2522edeae21
15175 F20101118_AAAGQL liu_y_Page_205.QC.jpg
9bebafff871cc85344021c2b558e3c7d
8ac48fba8adfeac157e28b568d10eb295cca7d03
3138 F20101118_AAAGPW liu_y_Page_197thm.jpg
0ce502adb7db454b3b9014296eaff3f5
2a6a51ebe2f001f349e20e0236535d2951b80ca6
F20101118_AAAFNJ liu_y_Page_063.pro
1617d24b31eb189ca10278de72e805d4
fd22f365b43f5526d6d850b2ce1804d1ca560c00
41829 F20101118_AAAFMU liu_y_Page_047.pro
7313d25515ee4641bcfd61af3988a1e4
67a97d1bfd15312d588252d5be831aef5379a461
7833 F20101118_AAAGRA liu_y_Page_212thm.jpg
cb4e610a82a7933df11c61cea8b896e9
a35ae847655e52082c3bc4da39c4f5047b5a1758
4193 F20101118_AAAGQM liu_y_Page_205thm.jpg
5d5991934a6b1bc29cf300f84037856b
83ba64f9a013c77c71b13c7972e2b03326549526
4259 F20101118_AAAGPX liu_y_Page_198.QC.jpg
3f175c9e5c4bd9b2e905bdd136bfecc4
59d7454d1706f9c6d5abf9472d3bf11a6cf78fbf
35386 F20101118_AAAFNK liu_y_Page_064.pro
edb0491509552631fe49f297b73d6179
084541dfc39ba392e8c60264b760a646b71c3144
53086 F20101118_AAAFMV liu_y_Page_048.pro
8520fe5c7e81223747ed994254f5c9d0
83622f1f642f470e9d9aa4771cd2cfbf02902a65
29607 F20101118_AAAGRB liu_y_Page_213.QC.jpg
33d2e4a3607378c813156f27d3bf2a67
87bb285bc15e059f4898eb6bd5db657a0aff55b7
15413 F20101118_AAAGQN liu_y_Page_206.QC.jpg
d3bb895fcdab45d398180e22b5db583a
14ce5f670712244b336dd7c65b2d4db7f566ad39
1522 F20101118_AAAGPY liu_y_Page_198thm.jpg
f40981e5cdcc12d5d3fb40a5381ee0c7
cb28d0b827d710a7f9d3f3a0b2770be2a7e2c682
51054 F20101118_AAAFNL liu_y_Page_065.pro
4b90cdce281e2ce6bcc872ca6173b4cd
65601f5908e6ca170133437e5fc72d194f909fe7
48709 F20101118_AAAFMW liu_y_Page_049.pro
095eb4053764ef82f1eaaf9d757667bd
1e4a75b291a5f1f44b4a68e0424c1e29b0694216
7674 F20101118_AAAGRC liu_y_Page_213thm.jpg
46afed439ed11293a82939afa516bc74
f743ca4ce114a7b813846f133d244f035218c945
4255 F20101118_AAAGQO liu_y_Page_206thm.jpg
c3eeb937f3f8f3739c42b051372381d3
3df53a7081a61981d1b6e1e3fa268055f22e671e
16325 F20101118_AAAGPZ liu_y_Page_199.QC.jpg
c269c5cc1996e0351553d0019e40c7bd
0891e5a13f47c4de073d5bcded45ea5e82e4e4c5
51950 F20101118_AAAFNM liu_y_Page_066.pro
c5a98eeda0a7d94437ca13cb1687d540
1094eaed803a7e49bbb510d8ac2c409b3580795f
53636 F20101118_AAAFMX liu_y_Page_050.pro
bf6c4d91996be15e13f992fc62240abe
aa456d1e9330cac63eb98e7a78049921ae334298
41172 F20101118_AAAFOA liu_y_Page_080.pro
805448cd525016ef82a895aa4a6b497f
f9b2e0e38da7db7cebf3e75bf465fa28635e830d
28048 F20101118_AAAGRD liu_y_Page_214.QC.jpg
f2bb90c265a8121e4a4f534b82692609
71f37154813bfc3b686c494c311bd7c05fdfb951
15354 F20101118_AAAGQP liu_y_Page_207.QC.jpg
abc6cb77465d0be4e7056d9524c3f618
9b8c120eb41fca7c888e865bf2d518c1e80d765b
53815 F20101118_AAAFNN liu_y_Page_067.pro
a9c11e11c5745eb20e2778441309d196
8bdd3deea83d61638f86340d6ccbb3b93d2ba519
55201 F20101118_AAAFMY liu_y_Page_051.pro
355c42f5ee0350adde5cecfc25e823b6
e55835d049a98075c120d06d0147639c650d2848
49257 F20101118_AAAFOB liu_y_Page_081.pro
a619cc2324bf2fde59e009aa4a24cf79
06258a6b0ebf2b717278ab0b60dd7e157e267916
7425 F20101118_AAAGRE liu_y_Page_214thm.jpg
3d240ffe1e5ee91004e720594f9ecab0
6b6e746abb83ed05d8915b306d8aedcaf98594fc
4257 F20101118_AAAGQQ liu_y_Page_207thm.jpg
04859bf3cc22b6625022d3036c8efa23
e6e85137375c959504e1af371fe6432001e414f9
46189 F20101118_AAAFNO liu_y_Page_068.pro
f2eaebf0b4ca8510a9ac46f58863fc91
10cf90f5896dd395202d7eb5fc13e89b3e0815a6
30773 F20101118_AAAFMZ liu_y_Page_052.pro
eb515586696f4623391ff366e91b11fe
bfba012ba70c31d4c2eae95ed3b4579aac080fd6
2010 F20101118_AAAFOC liu_y_Page_082.pro
06dad8e913cdc6171e940c751718aa6e
164dc3666028238c202252f1334ca7a97a5374f8
30142 F20101118_AAAGRF liu_y_Page_215.QC.jpg
ba90414ad6d30d7b65b10094c0a83c17
95211f180e6d844dc132103a9762fdfec9d8a27b
15574 F20101118_AAAGQR liu_y_Page_208.QC.jpg
19937597d67c003ecfb9c5ee94c0e224
af2e510dfc246eb8aae328b6e2f3f3f875de9239
32692 F20101118_AAAFNP liu_y_Page_069.pro
db8e563c96562e00c12cee1548226296
217a253c9ee9c0c0fec24cccdbe73c3160218e60
3089 F20101118_AAAFOD liu_y_Page_083.pro
359d21d337a35336dac6ae9b6cfed0cf
6c75e9ad4e8cb0ce742cfc0ee4afb7be2a482b42
8040 F20101118_AAAGRG liu_y_Page_215thm.jpg
fd370a139154e93e46daaca5a9c18464
acfafa44d132b51f0650a0d6e92ebfcdbccb5fc0
4172 F20101118_AAAGQS liu_y_Page_208thm.jpg
1e7a7ac78439dbc400bb486dbd9330bd
254dcc67a7129690a6e502a891df99f57381592d
33459 F20101118_AAAFNQ liu_y_Page_070.pro
f0dc87de25b1ee03e5a8ab72cd3f22d9
ec7c7d0cff286121d05e07db677aff39e426fc16
57631 F20101118_AAAFOE liu_y_Page_084.pro
d10a236a33ffccee95d6a126bd454bef
f009a62b44435b2f681e7cf6950f73c745fb7077
23631 F20101118_AAAGRH liu_y_Page_216.QC.jpg
3861cae418aa9b455a8a2b226107c3be
fcb21285158e9e1463b45db9fe8dce400f81107e
15426 F20101118_AAAGQT liu_y_Page_209.QC.jpg
401b427748a9b49c32328bcc0e9b0e06
103e86be8ea673bf68a740cc0e9100ab4ca3d735
49172 F20101118_AAAFNR liu_y_Page_071.pro
f1fe79c5f645e140f16fd47cbca65015
ce858df55f7ac21500e0f90279a5de98cee7e019
60005 F20101118_AAAFOF liu_y_Page_085.pro
1c49165503750780e7a90ee5fb9d1131
a37b4e3bcd3f6df18130a307dab8ee08f7522328
6515 F20101118_AAAGRI liu_y_Page_216thm.jpg
e6a1875d9d0b7362f03cba2c982d0430
7f32ffb27722f8f749d2de7187cdbfe4e2a14f18
4183 F20101118_AAAGQU liu_y_Page_209thm.jpg
17e9c0093d2ef55716ce73d05f9e95da
93b8598978d0c76786aa95010d5302ee9baf93e7
12144 F20101118_AAAFOG liu_y_Page_086.pro
790ca3673baace8a0508ed52ce74f455
0a97dcb997b76300580c37329546e0dc41c47f01
29839 F20101118_AAAFNS liu_y_Page_072.pro
86a23e8ae84a72ead17c838b4bd3bcf5
39095d0d6769332fc0c4490b51edb5056947927d
13604 F20101118_AAAGRJ liu_y_Page_217.QC.jpg
0ab6e7f06c974f91e092fe0f56024f35
3264579e5d0606d330e7ca933036e91116a54a83
5196 F20101118_AAAFOH liu_y_Page_087.pro
5a606d9b112269a4a316881767ce5b39
e5cd91b503924970c239861c03bd9364f82aa9c7
3856 F20101118_AAAGRK liu_y_Page_217thm.jpg
6f347dfc38a10bcbd0f3723da97d62aa
e7496c321f531f464b76add4f74ca1510701ed49
15488 F20101118_AAAGQV liu_y_Page_210.QC.jpg
b92a0480884cf7fafc31dea3a3f0a5be
02e564ad59ad4716bb5ccbf261348b705aa33046
31030 F20101118_AAAFOI liu_y_Page_088.pro
eb5796eee47b5469dd1b9eafdbeee989
44787a17113c3a1aabd569d2fde277d64d1ec1f2
27859 F20101118_AAAFNT liu_y_Page_073.pro
24cdfbc3320e433145b100f40f3b7dbc
16f3ba031c9d8b333f435d9cb31884c5dded457d
7300 F20101118_AAAGRL liu_y_Page_001.QC.jpg
e7f3310a4a504d83afc9b7a1bacd4b78
7002fd8db505ea70f18030eca7eaacbf7573e9a7
4231 F20101118_AAAGQW liu_y_Page_210thm.jpg
9535eebae9823aca7b90fd0d960e1b50
97b6d7ed2e92d0119e7d5254413520cdd4a7e78a
48091 F20101118_AAAFOJ liu_y_Page_089.pro
554d10e2f03d9de3a0435b992af04170
a275973e5951f0c799e7117e5212c967073e8ede
2598 F20101118_AAAFNU liu_y_Page_074.pro
eeb7b2bb581ffb185ed76fa139c19c42
10e05c91a3f83bae6b538f54b4a066326734a77d
7159 F20101118_AAAGSA liu_y_Page_013thm.jpg
99f99f44f11cc98bf6942daa01868dc0
6d755e83dd71ae557f913bc94ca8e202d2cb6755
1322 F20101118_AAAGRM liu_y_Page_002thm.jpg
aea15270b7b09a7e3cb96dea69b7c0d0
d444e942a77cdf912c028ca8dad5e7abd0984f54
28157 F20101118_AAAGQX liu_y_Page_211.QC.jpg
28bf042e5c097fd6774817dae39f80fc
7d0b80eee0dcd61995f0a1d6ec49d5b78d78ee04
14504 F20101118_AAAFOK liu_y_Page_090.pro
95b359d82f6642d621c8ed16eba4ce1d
59aff11bade029560981b3998c6cd96ed923b931
F20101118_AAAFNV liu_y_Page_075.pro
1aa8d53c011d9d4abf5b30ef457baa69
f21c62846375fda89eac79652bf86b8a0b340715
6817 F20101118_AAAGSB liu_y_Page_014thm.jpg
82c909b3be8a6483406ebe597994ba20
697c60981ef55941629ae3d53cde78c887370bc0
1951 F20101118_AAAGRN liu_y_Page_003thm.jpg
df22139d7e61ea136929610fa0cf4122
a05190491596a70e341710e458b6d4ffa7821b24
F20101118_AAAGQY liu_y_Page_211thm.jpg
fb9d1886a38497750cc5928d80cbb620
8766cbea32ffdbf4e8c3e62ecbdaaa807e6b2098
37208 F20101118_AAAFOL liu_y_Page_091.pro
8d93a38d44e5d92a0fa22bd3bd4e9420
be0568d90d057e1d01fde9184eaba5d8b74e2aa4
35298 F20101118_AAAFNW liu_y_Page_076.pro
c7f514f421dfe64c77e7eec7677a9a8a
073dc341b54ccceb16f4c0876a4a36b4777da677
F20101118_AAAGSC liu_y_Page_015thm.jpg
8e131488ccf6c26bdcd2216aca593269
9f513013b8bad107b58bd4eb41af868ea1c4d0b2
1938 F20101118_AAAGRO liu_y_Page_003a.QC.jpg
9932127fc5619208205a2d5537b781c4
d14e55de3de533d35c1e7d929731a7ed23bb4563
29102 F20101118_AAAGQZ liu_y_Page_212.QC.jpg
917a78707a21bfa7d5bceb7dfebcfab4
a8b1cdc153abe04b68d0857064abb04e44d6a1e4
60523 F20101118_AAAFPA liu_y_Page_106.pro
dd9363a512586b2c89c6ea191b8e11b6
6ab2eadc28ac684da2c325ad1cc78447d48af258
37595 F20101118_AAAFOM liu_y_Page_092.pro
af04252c37877549568fd34f44400975
883b3ceb04d4ed85d6b7fe85897a878a3dcea77e
5618 F20101118_AAAFNX liu_y_Page_077.pro
08e86875b40f44b1b91291cdd55d145e
bdcece0cd5ce57b6c3dd059d7ae5dd403009f9af
6823 F20101118_AAAGSD liu_y_Page_016thm.jpg
2ebc5a3320d257775697f4355b999ab2
b16b4024095bb0ded5d2f05128c368d5cf09a256
764 F20101118_AAAGRP liu_y_Page_003athm.jpg
cf03b1f5d80caf6cff087a97f6d295b6
7ec011c7c1ce1586078ec2fcb6e3510cf7166bb4
22758 F20101118_AAAFPB liu_y_Page_107.pro
c37a4a9095a332367363392ca265f999
47b3c7ba2dde7904e053e846fa3a2f518211f972
5918 F20101118_AAAELL liu_y_Page_155thm.jpg
f9bf6a0932885b42ea977eddcc281d7e
3e519c4408be769f66671853407500a2318cb50b
28727 F20101118_AAAFON liu_y_Page_093.pro
8602c5b3ead128113046abd66b533857
f85b1a44c8d8e49d4552a28edd31b5116747fc75
32182 F20101118_AAAFNY liu_y_Page_078.pro
238553043f942a5b265add073b1a42da
4187427aacf6ea3534f9414f22e7b7d184443ac3
5535 F20101118_AAAGSE liu_y_Page_017thm.jpg
931dbb70b1cfc42840eef6b895f2601d
d20da57899b394d119ee767f10856270b3a69641
25470 F20101118_AAAGRQ liu_y_Page_004.QC.jpg
ebd7c261e937690004f081e7116f978c
b9a3a7bf9d4e708d5ced10b36749abce62d45d89
23418 F20101118_AAAEMA liu_y_Page_001.jpg
edfd05b3be8cec17731d0849041a4aac
6fad76b7d2f797ca72298c5b5e5d17e8489f156e
19604 F20101118_AAAFPC liu_y_Page_108.pro
f117c7c9d21ab47b4e995ef5e41bd88d
fdf58d413c4da468e3be72db6e11246ca1c57fb3
F20101118_AAAELM liu_y_Page_112.jp2
42013e6f1c466f04cbf74a2d89aec320
872075db665bbc8d2de8b9c37f337731170a9027
58494 F20101118_AAAFOO liu_y_Page_094.pro
0271c9a4a02e9c972ab0b9103feef582
97d586036a2c140530cfc6dd9f7eb3704f29df39
31188 F20101118_AAAFNZ liu_y_Page_079.pro
cca7f5bf0aea4ee91f60879a06a81468
7b1ee313c51a160ff2893110965832453f652e58
7310 F20101118_AAAGSF liu_y_Page_019thm.jpg
f46b1e67e1a0502cb6380997bb3ef49c
837a04ea475d85d57eceb0153af1083bc42d11e6
7155 F20101118_AAAGRR liu_y_Page_004thm.jpg
a24642408496e7cc37ce39c725f5f35f
e2abb7c6a0c9841a9dae2d0d8f59867e15180566
9820 F20101118_AAAEMB liu_y_Page_002.jpg
f8aca872cb2634133865b0d696abb76c
ac47faedaf85c5afd1ef2c53840aec1b09868b73
6118 F20101118_AAAFPD liu_y_Page_109.pro
fb63fa4a4219db3327c44804fd495f33
cda1ced9352e4e1061cf579c66fe98111c5a1091
21746 F20101118_AAAELN liu_y_Page_053.pro
c8f6e94fdf112605af5d4eeca9134d7f
9b5236bc9563a647ad179cfac3df9dc99502c31d
24934 F20101118_AAAFOP liu_y_Page_095.pro
79a6404cb4ee1b9e418fc96ed281e81f
a80d1d4b2b83025a11e4ef1850dd2d68bb9d84e3
25117 F20101118_AAAGSG liu_y_Page_020.QC.jpg
a76cdbd7e2e2b35381e3a1d83b038613
9039d596a06f7f28e857b3acf7d3dee9b22e0ed4
25631 F20101118_AAAGRS liu_y_Page_005.QC.jpg
0c546c3069b11243d3fb3a5f0315189e
0a69b26e69effabce346bd1a1c60db27198bbc50
19459 F20101118_AAAEMC liu_y_Page_003.jpg
a35d0facc771d7e53416db367ce260bb
be09921e6776639e0a57bc2449fd01f1627ee086
5198 F20101118_AAAFPE liu_y_Page_110.pro
341a4935a19c57b2c5aad080135d3456
4cafb9baf308332c38a6cb0ab3ae66299bc0c416
6968 F20101118_AAAELO liu_y_Page_018thm.jpg
9e4183b582ebbf0e858751aa88436389
dc8765882164768057725c768d833db31e93ae5b
14670 F20101118_AAAFOQ liu_y_Page_096.pro
7cf9a2db09fe652eb317c2f101175f04
4cd3942ab6fa2e954466c6e6f1de8ea83197c43f
246674 F20101118_AAAGSH UFE0021579_00001.mets FULL
1ff3a6216e2791a22aa385bde137d3e8
343fb56dab84be870e3bff71bb16932fd0b086e3
6604 F20101118_AAAGRT liu_y_Page_006thm.jpg
7fb995dedc919b3fb11664da41accace
9f747c3d6abbb33f85596c9bf947e1f0ad61e488
80779 F20101118_AAAEMD liu_y_Page_004.jpg
1b7ce703d9b93e1b6d26dc3ba56b73cf
ab774d812196093cee6df98081fe68a2f95c7a40
F20101118_AAAFPF liu_y_Page_111.pro
50829ae5d9bb37de384fa9c42b415722
db07515bd3e5248835ae64af0dbc2fcc2bce5030
97472 F20101118_AAAELP liu_y_Page_145.jpg
20887847b1efed24d61580444c7db3b8
d599d1c6ebda5c433b73c9039ed5ab732c47b29e
34193 F20101118_AAAFOR liu_y_Page_097.pro
a1e09e8a014600b7df66d036358a5fbe
94ce25597f61b399521fad21fe97a895c80fc814
7405 F20101118_AAAGRU liu_y_Page_007thm.jpg
70621638baf805c128669badf8396064
96f45e4a8ca63c7f3456935ce3b57a92515c4c16
100764 F20101118_AAAEME liu_y_Page_005.jpg
b4b110944e62350a19c14c3b787b207c
510c1d0c8fc65c8c19786f79a791041a38209c3a
56716 F20101118_AAAFPG liu_y_Page_112.pro
74a1f871dc5550def801ed3a6dcfb01e
a5536f05f8836469f29a7038598f67baa0f00b91
4574 F20101118_AAAELQ liu_y_Page_123thm.jpg
1724fe249563e253873f869f021da0ea
a24d509a190ed4718de29b696ee0322480ff3a22
44507 F20101118_AAAFOS liu_y_Page_098.pro
ed41c053572f8d9fc96cda71090efe9a
471e1284da195398ce74784afb2cc2499ee3aca6
3366 F20101118_AAAGRV liu_y_Page_008thm.jpg
6d4e2d7c52af0870bde12edc6412ba66
240cc6a11cfc90520b26f6934c794487accc720a
108686 F20101118_AAAEMF liu_y_Page_006.jpg
e967ef80b7b15860a1c3b90c56575d97
a31217b7f31db8c1af6f6142227b4141fc99d94b
26966 F20101118_AAAFPH liu_y_Page_113.pro
2e21a0ea9aea23a0f5eaf26c2cdf5821
e5a9b4cf2392ad884f16e31e3ab76827488f814e
18765 F20101118_AAAELR liu_y_Page_140.QC.jpg
d08dad36a7c7e58048554fa48fa9e643
1b1854664a16eb4424a19ac1ea9fd28ce2ed4cf9
5224 F20101118_AAAFOT liu_y_Page_099.pro
d8ff85609b39cecdd61312a4f120609a
0d5a3f52f7fa447e6a1fe53366dddba4a09f79ce
129073 F20101118_AAAEMG liu_y_Page_007.jpg
08ebff4cbaff82e46d623498b2830713
f56799bb611d28355cf45e48b0a5763553e00897
46088 F20101118_AAAFPI liu_y_Page_114.pro
3daad3d3599108539b6986b863301f42
84228de0695b6037dc28c44e4b48a281ec3c2818
6108 F20101118_AAAGRW liu_y_Page_009thm.jpg
324370a1e73da5f00210bc6ed13afb91
4f0b6255b4b28107f45a89d0288ac426486bc382
44625 F20101118_AAAEMH liu_y_Page_008.jpg
8c737571f2d4d943348b579e12d4e7fd
2a5184a3d5164f4afe689cae4bbe4e8e185ae872
9696 F20101118_AAAFPJ liu_y_Page_115.pro
c10a345f3579c82ba60617b1199087ba
b1d7165f433e86b543b0888c802d141604c9270d
F20101118_AAAELS liu_y_Page_135.tif
1ff868e4217938d3ab5238c40c4b5f91
52e4dc9d74a41eaf328a87a8a830d9f47674893e
F20101118_AAAFOU liu_y_Page_100.pro
3021b741cd8cb046d5e1da64bb502052
b73bb7a26916e2085976c99000af5e15bc7ff38e
4783 F20101118_AAAGRX liu_y_Page_010thm.jpg
580525d4dd24c60f913f080f2aec444b
06b3685d71ce3650ea436e480f97d0d355e831df
83964 F20101118_AAAEMI liu_y_Page_009.jpg
807fd6c084e8dc42dd2e7701de76e7c3
c6a22d804b78a3b0c46002d34f4aaac82f4b773e
59955 F20101118_AAAFPK liu_y_Page_116.pro
5466b7954add912bfaf4585fb5bcefa4
9e3ad807fe1881abb6130e2c4bac2f2d7ae51011
25613 F20101118_AAAELT liu_y_Page_065.QC.jpg
de5255e0d6d411bd414f4f45d2ece229
4b719548477d330fac44787134388161b46627d8
38061 F20101118_AAAFOV liu_y_Page_101.pro
834079524889d8faa7fe4d0ed05d1006
14c6670e70a85e3f156c0de90769b08fcf842e79
5692 F20101118_AAAGRY liu_y_Page_011thm.jpg
e79a16af4894ea6df110fa08b8e74354
1b87ee9e6544ac3c16f8c20177234a0f211942df
58746 F20101118_AAAEMJ liu_y_Page_010.jpg
08fe0b16509d827b6743f2f0b213acbc
2fdb238b95f00003901c039ab33b3a5b37c5029d
32788 F20101118_AAAFPL liu_y_Page_117.pro
0ba21ff992478b4e466b0ff7f25552d7
f3f0d363aa4ce8f9d8715bcee5950dcb92a76135
9158 F20101118_AAAELU liu_y_Page_107.QC.jpg
f8ec7fd7cb92748353704803f563351b
a96795a1c8ea7b56a0cc96827816e8395efb0943
45255 F20101118_AAAFOW liu_y_Page_102.pro
d31015b2e481f68acff85dde0cac9a5d
b511fd8294dcf16bfa4fc5d551a2c1d71d81653b
7343 F20101118_AAAGRZ liu_y_Page_012thm.jpg
a796221a82639dcbde9e043779caed16
1fa1de39e46af2a21c866aef50d80a587288d499
42418 F20101118_AAAFQA liu_y_Page_132.pro
a8e5f4fd530c8b539320b48958930f31
24d7bf893f39cda70e9cc2de137d70b91c6a9894
76530 F20101118_AAAEMK liu_y_Page_011.jpg
dc4aec47b06323af879bcdb84204f6af
de620b71320d4b5c9c97035709e2cabb291ee795
12017 F20101118_AAAFPM liu_y_Page_118.pro
7f03c117dc677ad029b372436b6bd0b9
1924984d2042318a9aaf826c6893caae2613f81b
27232 F20101118_AAAELV liu_y_Page_128.QC.jpg
0073f94bff9e102fd306ed32a2012966
694eb97704aca95da39fb09c8449464ccaebe2dd
49314 F20101118_AAAFOX liu_y_Page_103.pro
6f306ad63fec24ba9d46ba12b8db078b
86d3b1a867e21d2a69537aee5f86208b19229240
51029 F20101118_AAAFQB liu_y_Page_133.pro
de18cae649cde16dc6f3884112587729
d17f6bd2a906bd6bc53708fcfe0fb37c8d07aba5
96074 F20101118_AAAEML liu_y_Page_012.jpg
2013fa4450b1e9e00f060840fe91f0ae
52c6ed12e944013e78676762ce251c5687b23dad
24181 F20101118_AAAFPN liu_y_Page_119.pro
5497f26ad82bac958fce5d74b239f286
15d5a4867500f4f479f66c2e75aa0f47e0da5de9
47567 F20101118_AAAELW liu_y_Page_045.pro
f8d16b3d48168b54212b2cd416168ab1
0ccce38f09536de3732baf5c99954f9505443876
52426 F20101118_AAAFOY liu_y_Page_104.pro
639d0cf922ebc412f520e6879ea04ebd
c84d3c964f0cb01c1b4e6a986a008468f3c1484e
40240 F20101118_AAAFQC liu_y_Page_134.pro
65f807c682d390f71d060e5827368940
5aea1051e1057260e8f622f2497934f459880829
93147 F20101118_AAAEMM liu_y_Page_013.jpg
23c4431e599ed91d506270bc6cd14795
d16b8a917660ae33c255f1f92503f8b97fff1b7e
49886 F20101118_AAAFPO liu_y_Page_120.pro
dc20fd3e2e4fb54c7b993f4d12445f99
d6cc0fcc24c1d7e20ee4ef1a42f3244b61f0e28b
319629 F20101118_AAAELX UFE0021579_00001.xml
2bbe6e1e84d7629c4140289407f9fca6
81de150d51975eae80ffcea9a93712f1f7645055
19546 F20101118_AAAFOZ liu_y_Page_105.pro
f9a14257a89f6314a28397efff0ec0f8
37cdd4c795a6410dfbe8968591dbb1d52889a9c7
81228 F20101118_AAAENA liu_y_Page_027.jpg
ba3f9df3424abfe0d3d216a20f697a9a
d05bcf694dd93ff01c810a5e5670bc3d95d5f676
30948 F20101118_AAAFQD liu_y_Page_135.pro
62d747324f82761f4cb61bc76fd3631e
ff78a9d2666a42d54b1f7d65eb62b1567cb9f141
92284 F20101118_AAAEMN liu_y_Page_014.jpg
96d2c5cefc6ac9808a004e4e114d8d9d
114fb3e0b64f34d05715300968c94c35d0f198d6
51225 F20101118_AAAFPP liu_y_Page_121.pro
ee98d2ca21165d8fc9ac5b989c298c24
e7910d22eb8e36b8d0843ca698323c5b632a4c2f
58189 F20101118_AAAENB liu_y_Page_028.jpg
037b150aa2eb2ed712c29f94148385c2
96a23a38ec7a7a5fa7e81bec93355aa93344f593
38994 F20101118_AAAFQE liu_y_Page_136.pro
3196892c03b0c272f9aa7514b756cb35
9f525e781dc5a7cd8c6aeba46894067c77f2e20c
27335 F20101118_AAAEMO liu_y_Page_015.jpg
4c49d211ab528f85b5d49592b658c0fc
72b457f0f14517d333e352e61f4b14882168c38a
31039 F20101118_AAAFPQ liu_y_Page_122.pro
8f74b0408fd7f346a891fe2fa13b8c61
04f90f3b50c4225419d472749273ea121ab2bd40
79674 F20101118_AAAENC liu_y_Page_029.jpg
1bed702386d99c76172dc8990c382237
7426179873905102f91027f32eb1a3bbce6357c6
51280 F20101118_AAAFQF liu_y_Page_137.pro
dd040169e6e3e5941994b8c633ffbc35
146ae50c0553a06a37326f37e189461e5fc5bed5
18741 F20101118_AAAFPR liu_y_Page_123.pro
b4a1e64b26a3f5101b003471f0d21104
791f3caff9829564961cce82e64f14f4d220f5c3
75586 F20101118_AAAEMP liu_y_Page_016.jpg
551363a8b73a141a08159be842e80efa
3b8f29cda4b8494156a3326aff14f8074c1e723f
87286 F20101118_AAAEND liu_y_Page_030.jpg
c9f567d2e139130869c218bae2391c34
c53016790f59b319a9a2f908528c9c34ea78f00d
34149 F20101118_AAAFQG liu_y_Page_138.pro
1ffaf9fdda3f0497fd8069ef9148dbdd
ce242b97202e0e138e402573cbeb1dd098ee5e60
54795 F20101118_AAAFPS liu_y_Page_124.pro
fc781e15a265a5da6663097650631d7a
c42cb102cf9ccc699a2a408dea9a878cdb333c24
61159 F20101118_AAAEMQ liu_y_Page_017.jpg
5894e0edac14fb7631e7301d5791f7da
40b186d8b7139301049d1873128c9a9080215916
84672 F20101118_AAAENE liu_y_Page_031.jpg
b0d9c7850efb1beee8b43f49e46650db
c43346b504d586916fa88df4dd67bbaee54ba602
29016 F20101118_AAAFQH liu_y_Page_139.pro
0cd0499d75b4d1360619b7ad21ad6671
3d056999afaf56e2d9dbb0dcaf6625261d7883c9
43034 F20101118_AAAFPT liu_y_Page_125.pro
1a26ea040fc7d8c92b684e99cc283c98
484ee4f57918d61198aa526e154bded149b56ebc
82274 F20101118_AAAEMR liu_y_Page_018.jpg
58ecc51c2dd2078c59b9d479c723bc72
81993c52d7af0abae465bc85f1d13a721f9866df
63910 F20101118_AAAENF liu_y_Page_032.jpg
6394229e5e0c2e036151d623aa529bfa
9363bd9aeae29e953d04f9fe840258be2da53fa2
37798 F20101118_AAAFQI liu_y_Page_140.pro
15eb7993604edea7ade4d8cac08f4ca3
89822a32d1305ce8298d92a7c1900fd82e1f20ae
50627 F20101118_AAAFPU liu_y_Page_126.pro
9d00df425d097a37437b1788d5f12783
be0df2de8a3515dc5d59c2363947a2d8069220ad
84464 F20101118_AAAEMS liu_y_Page_019.jpg
fcbb80d8e95dab54ee1aa0ab28d79540
83c803defafe24918d83c2524f0143c671bf4051
42661 F20101118_AAAENG liu_y_Page_033.jpg
38550383a473d2df528ee9a53fed6f72
a232288b584f6fbb99143a8e35f0fc2b6f262ba7
39080 F20101118_AAAFQJ liu_y_Page_141.pro
17290f6e8af016550621aa8ee8c552d2
192f4cbe7c32564c90b265e37f79cb661754eb5e
62984 F20101118_AAAENH liu_y_Page_034.jpg
d60abcfb948722d20ce39d5163802e78
3d91522cd5e7435d78d6e9a8cffb3e16e6873020
40415 F20101118_AAAFQK liu_y_Page_142.pro
9077822fae93535f39ae855e79bc1e6e
87cd2fff151dd0930f1c2356f03e798336f3fd99
67591 F20101118_AAAFPV liu_y_Page_127.pro
7c29ba2261ecc1fa2ad155a049b5ec42
970f88eedc3ea9768d85ce55909c0fbf58be8240
83308 F20101118_AAAEMT liu_y_Page_020.jpg
b746174ab57e0340f6b4091a8275d873
316b6210d0c64da6cb9f8f792b65a05dff888e25
84761 F20101118_AAAENI liu_y_Page_035.jpg
846d26196bd2ebf891d750fcb4d6e942
1a1e4051fda32b108f494a16db622a01bab5c7d7
37701 F20101118_AAAFQL liu_y_Page_143.pro
7d4f2b97e806dcbc43f866ebf25ecdfd
132a3274789d396edb3230f905733e104250cba9
51812 F20101118_AAAFPW liu_y_Page_128.pro
78eba99d1836750bc232fcd7eda5247d
beaa4936f6bd3b752e819e0ea34dd268dd958f96
57744 F20101118_AAAEMU liu_y_Page_021.jpg
5097f80de39725b5839892074a6f2862
3fbbd8fabd3141d2fe50b85a20d73f80641e9100
77282 F20101118_AAAENJ liu_y_Page_036.jpg
ce04e26eb945eadf6421099fc21531db
885e5257a5a48b6b2ebb6f2c52a4b1f81e44f627
19766 F20101118_AAAFRA liu_y_Page_158.pro
054ecdfdb7a21f8b10a60b58e61eb973
7622e4c12bea038bb2a7dc5feeedfaf1b419b16d
34621 F20101118_AAAFQM liu_y_Page_144.pro
7963c2d52ae3ad085fedc1dde7245c62
cda5d14de14b225ee1aa4d1393f7c542cd41177e
35451 F20101118_AAAFPX liu_y_Page_129.pro
5e7d6de54dd0f802bd93fbc1c06f56cf
de3f3a641ddcb7763740dc241ce6c0fc0b9c9268
75606 F20101118_AAAEMV liu_y_Page_022.jpg
64744d4f2e1f40a5b643c3d1f027531a
605ac0553da99ab4074770b733c2861f27a2d116
84173 F20101118_AAAENK liu_y_Page_037.jpg
ba1acef7b05fa05dc7f19bb092743d66
9b249e41f960a45989a6671d2b60c5b070985e2c
32908 F20101118_AAAFRB liu_y_Page_159.pro
0f5e6700a0e4bf9a68b0539d2be1c398
cbc415e69046cea4e254553041b4f611e6a8b63b
70881 F20101118_AAAFQN liu_y_Page_145.pro
bc00bf7b2c9002b5cffa70b4b851b05a
fc50db4ee173d94cdb9d355d6451f063506668d5
34599 F20101118_AAAFPY liu_y_Page_130.pro
6cdd6cca605a9acbb7bd7051421c6b57
f7d3203a21cbdfbb54d96fa5db0e611a58e2261f
87682 F20101118_AAAEMW liu_y_Page_023.jpg
14eb9be69b39bb6f9ca5ce3a938ef760
03d94df01e0bc39c9de63d266c59e1eff637b182
87539 F20101118_AAAENL liu_y_Page_038.jpg
f5944a1e13884754c4c5f1f7817d390c
1b31bad148e6b79ee83ad1d17328fc29602c5c71
17837 F20101118_AAAFRC liu_y_Page_160.pro
261e1b46d566744da0cee1eb44a23d48
cc4ee960562433ba17c7de363a82ff8316f3e09c
62291 F20101118_AAAFQO liu_y_Page_146.pro
26a6472f41f5d5687d75ce6f366da3b4
64738840604ff9eb3fc4eeca571e96656cc91a7a
37659 F20101118_AAAFPZ liu_y_Page_131.pro
7127975a049716dc13b5e2a7c7df0cd6
0aa14dfef702b1548ce467d3384dde2931364e24
82960 F20101118_AAAEMX liu_y_Page_024.jpg
8420e461a7d2059854f92b928c11019d
0b34384e706420a1ebae9bdceb8da3356fd59c31
40819 F20101118_AAAEOA liu_y_Page_053.jpg
8255a1daa8fb9301442212c3d18c18af
bc90412a41fc63adb20ae2f6740e410bc31f8458
79045 F20101118_AAAENM liu_y_Page_039.jpg
6834a3e9a9c5a2a5e56ee05957ae83f7
12bbd6f1fba7c5938a270c32aa8a615446da2470
21809 F20101118_AAAFRD liu_y_Page_161.pro
25b15e67e8543b83c3ba1a92ad957158
b11cee200d850052c2da036b5fb86bd663efa43c
48125 F20101118_AAAFQP liu_y_Page_147.pro
d605f8872fbe7be2fa923056b974e376
81aa000e80be1d990f921aa3fb77721f4f66ba3c
78008 F20101118_AAAEMY liu_y_Page_025.jpg
a8ee5c2b177eae07a08a6544a88af851
1a18bb6046886ba531f1d01902e32ad10bc9ad6c
31889 F20101118_AAAEOB liu_y_Page_054.jpg
fc7b75c9fb6689e3abf35eb65b3e6fb3
a4bb4ba617f13426c6f1a067926ce627b4b2a157
80495 F20101118_AAAENN liu_y_Page_040.jpg
e923772af5290b88dab1aa9fce3a0184
464c8d652ee7ba11ac410a77b15c1d62afca3dc2
52791 F20101118_AAAFRE liu_y_Page_162.pro
fa3a809c9c27454b31a2a6f4dc239ce9
7dfc013b6999177305b35059cfaa314d81620e6f
49964 F20101118_AAAFQQ liu_y_Page_148.pro
4fdf9f8b8a63c33983ab373f0ba817b0
5c0388ebbf66fa63d340f4585302562b46f0f2a2
60335 F20101118_AAAEMZ liu_y_Page_026.jpg
e7a23e8125859351610c950a4c276f3a
75809c7754ba7880078e735a92c7cfebd0267066
60391 F20101118_AAAEOC liu_y_Page_055.jpg
866e4c531b7f0b99026814136a4fee3c
f713888aeb536e918029b06e9b88dafb14800569
88832 F20101118_AAAENO liu_y_Page_041.jpg
53ec6b691d0062e238cd39fae0ee45ab
7570252419a35b76d0d8da4b5a4c45e6d22b1a1f
19964 F20101118_AAAFRF liu_y_Page_163.pro
44101c49e2ff5834f29a915c112a6a0d
7efe99b78ebfa1dfb471f057c1a592161c471761
18725 F20101118_AAAFQR liu_y_Page_149.pro
3be8451a34d1c86e3cfd948fdba15d15
5ebaba695e74c7014794eaf07870f949bbc5af29
10798 F20101118_AAAEOD liu_y_Page_056.jpg
a68321dc0db8b94c08dbb3512876179c
542ff11f6fca5782dcffee5a3a91125e55fae2fc
74405 F20101118_AAAENP liu_y_Page_042.jpg
c484c1bf461513829ef3662ff3db9bbf
aeacc0476e52834afbe019bb98eae34402abdcfe
31564 F20101118_AAAFRG liu_y_Page_164.pro
2e731422f81c4802d3687f232e3af5a9
644f3a9eb9f4d90622f78be78a49a2939d8387bc
51087 F20101118_AAAFQS liu_y_Page_150.pro
9853085a75e17a7b1d7cb8159bebe9c7
e823aad96cb6d799bece753a9e18ef9fa7f2325a
78422 F20101118_AAAEOE liu_y_Page_057.jpg
9562374c4cb359a9a537adfff778b579
78f86cfb6af1a3b013dced4080cc32864a3995e4
39420 F20101118_AAAENQ liu_y_Page_043.jpg
b939fe83b93a558294bb7ed38fc99a19
a83ff02066a8c2bbd4346ab70eda2c7010bbdda4
34395 F20101118_AAAFRH liu_y_Page_165.pro
0420a55662618d0ca75c15655fa3b6e4
2e514f1252e3e0ca456f317848d80ab99759e521
40937 F20101118_AAAFQT liu_y_Page_151.pro
dbea3b84013e1559dfe060294cde27e9
9f497ac42e7210f946887d17e92ab468b17bc7db
80408 F20101118_AAAEOF liu_y_Page_058.jpg
9f12965bbfff3b3fbef2a7824ba9ac55
f44bce5d6a6855f650be2f55254456031309de69
54019 F20101118_AAAENR liu_y_Page_044.jpg
fb9f34654f7ac212fdd05e5ff1267cbe
f3ccbf8b3c0acd7816b81a4e511f63fe87ad77de







STRENGTH, MODULUS OF ELASTICITY, SHRINKAGE AND CREEP OF CONCRETE


By

YANJUN LIU


















A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA

2007



































2007 Yanjun Liu

































To my Mom and Dad, Ren Shuzhen and Liu Yuchun, for everything they have done and are
doing for their child, my daughter for her understanding and consideration for 6-year-long life
without dad's company, and my brother and sisters for their great support and encouragement.









ACKNOWLEDGMENTS

It is my immense pleasure in thanking the persons and organizations that helped me over

years to bring my PhD dissertation to the final form.

Firstly, great appreciation goes to the chairman, Dr. Mang Tia, and cochairman, Dr.

Reynaldo Roque for sincere encouragement and patient guidance. You are the beacons guiding

me throughout my tough trek of pursuing PhD. Without your help, this dissertation can not be

completed. Please let me regard you as loyal friends and great mentors.

Secondly, great appreciation goes to the members of my supervisory committee, Dr. N.D.

Cristescu and Dr. Larry.C.Muszynski, for your great enlightenment and keen research assistance.

Thirdly, graceful acknowledgement extends to Florida Department of Transportation

(FDOT) for providing the financial support, testing equipment, materials that made this research

possible. The Florida Department of Transportation personnel Messrs. Michael Bergin, Richard

Delorenzo, Joseph Fitzgerald, and Craig Roberts are appreciated for their help with the entire

process of fabricating test samples.

Fourthly, I like to thank all my colleagues in the materials section of Civil & Coastal

Engineering Department. Danny Brown, Chuck Broward, Nard Hubert and George A. Lopp are

acknowledged for their assistance in this study.

In addition, special thanks are given to the Florida Rock Industries Company for donating

slag, Boral Materials Company for donating fly ash, and W. R. Grace & Co for donating

chemical admixtures, and Carolina Stalite Company for donating lightweight aggregate. Without

your sincere help, this study could not be completed on time.

At last, my sincere thanks go to my parents for their persistent encouragement and

unconditional love, which motivated me to complete my study. I believe the fulfillment of my

study will bring you joy, which is the only thing you need from your child.









TABLE OF CONTENTS

page

A CK N O W LED G M EN TS ................................................................. ........... ............. 5

L IS T O F T A B L E S .........................................................................................10

LIST OF FIGURES .................................. .. .. .... .... .......... ....... 12

A B S T R A C T ............ ................... ............................................................ 17

CHAPTER

1 INTRODUCTION ............... ................. ........... .............................. 19

1.1 Background and Research Needs .................................. .....................................19
1.2 H y p oth esis ................................................................2 1
1.3 Objectives of Study.................. ...................................21

2 L ITE R A TU R E R E V IE W ........................................................................ ... ......................23

2 .1 Introdu action ............................................................................................2 3
2.2 Strength of C concrete ................. .... ................ .................... .... .. ........ ............ 23
2.2.1 Significance of Studying Strength of Concrete.....................................................23
2.2.2 Effect of Coarse Aggregate on Strength of Concrete...........................................24
2.2.3 Prediction of Strength of Concrete ................................ ................................. 26
2.3 Elastic M odulus of C concrete ...................................... .. ......................... ...............27
2.3.1 Definition and Determination of Elastic Modulus of Concrete..............................27
2.3.2 Significance of Studying Elastic Modulus of Concrete ......................................28
2.3.3 Effect of Coarse Aggregate on Elastic Modulus of Concrete .............................29
2.3.4 Models for Predicting Elastic Modulus of Concrete ...........................................32
2.4 Shrinkage Behavior of Concrete ...................................................................... 35
2.4.1 Origin of Shrinkage of Concrete ....................................... ......................... 35
2.4.2 Significance of Studying Shrinkage of Concrete ................................................36
2.4.3 Effect of Raw Materials on Shrinkage of Concrete...............................................37
2.4.3.1 Effect of aggregate content on shrinkage behavior of concrete .................37
2.4.3.2 Effects of coarse aggregate type on concrete shrinkage.............................39
2.4.3.3 Effects of size and shape of coarse aggregate on concrete shrinkage ..........40
2.4.3.4 Effect of other factors on shrinkage behaviors of concrete........................41
2.4.4 M odels to Predict Concrete Shrinkage...................................... ..................42
2.4.4.1 CEB-FIP Model for shrinkage strain prediction ............................. 43
2.4.4.2 Prediction model recommended by ACI-209 Report [1992] .....................45
2.5 Creep of Concrete ................. .. ...... ...... .......... ...... ............. ..........46
2.5.1 Rheology of Materials and Definition of Creep of Concrete .............................46
2.5.2 Significance of Studying Creep Behavior of Concrete .......................................48
2.5.3 Effect of Aggregate on Creep of Hardened Concrete ................. ... ............ 49
2.5.4 Prediction Models and Their Limitations of Concrete Creep .............................51









2.5.4.1 C .E .B -F.I.P M odel C ode ........................................ ......................... 53
2.5.4.2 M odel of A CI 209 ...... ................................... ......... ...............55

3 MATERIALS AND EXPERIMENTAL PROGRAMS ............... ............................... 58

3 .1 In tro d u ctio n ................................................................................................................. 5 8
3.2 C concrete M fixtures E evaluated ........................................ .............................................58
3.2.1 M ix Proportion of Concrete...................................................... ................... 58
3.2.2 M ix Ingredients .......................................... ............. .... ....... 59
3.3 Fabrication of C concrete Specim ens...................................................................... .. .... 60
3.3.1 The Procedure to M ix Concrete ........................................ ........................ 60
3.3.2 The Procedure to Fabricate Specim ens ...................................... ............... 66
3.4 Curing Conditions for Concrete Specim ens ........................................ .....................66
3 .5 T ests on F resh C oncrete.......................................................................... ....................67
3.6 Tests on Hardened Concrete ....................................................................... 69
3.6.1 C om pressive Strength Test................. .. ....................... ............... ... 69
3.6.2 Splitting Tensile Strength Test (or Brazilian Test)......................................... 70
3.6.3 Elastic M odulus Test ........................... .................................... ............... 72
3.6.4 Shrinkage Test ......... ......... ...... .................. .. ..... ...... .. ............ 73

4 CREEP TEST APPARATUS DESIGN AND TESTING PROCEDURE .............................76

4 .1 In tro d u ctio n ................................................................................................................. 7 6
4.2 Creep Test Apparatus ....................................... ........ .......... .. ...... .... 76
4.2.1 Design Requirements of Creep Test Apparatus ............................................. 76
4.2.2 D esign of Creep A pparatus .................................................... .......................... 77
4.2.2.1 The determination of the maximum capacity of the creep Apparatus .........77
4.2.2.2 The design of springs ............................................................................77
4.2.2.3 Design of header plate ...... .......................... ..........79
4.2.2.4 Determination of the size of steel rod .............. ..................... ................81
4.2.2.5 Stress relaxation due to the deflection of header plate and creep of
co n create .................. ...................................... ............................. 8 1
4.3 Design of Gage-Point Positioning Guide ........................................ ...... ............... 82
4.4 D design of A lignm ent Fram e ........................................................... ............. ..82
4 .5 M echanical Strain G auge......................................................................... ...................85
4.6 O their D details on C reep A pparatus........................................................................ ...... 85
4 .7 C reep T testing P rocedure............................... ............................................ .................. 86
4.8 Summary on the Performance of the Creep Apparatus ..............................................93

5 ANALYSIS OF STRENGTH TEST RESULTS....................... ...... ...............95

5 .1 Introdu action ....................... ...... ............................................ ................. 9 5
5.2 Results and Analysis of Compressive Strength Tests.......................... ...............95
5.2.1 Effects of Water to Cement Ratio and Water Content on Compressive
Strength ....................................... ........... ..... .. ..................... ............ 95
5.2.2 Effects of Aggregate Types on Compressive Strength .........................................98
5.2.3 Effects of Fly Ash and Slag on Compressive Strength of Concrete.....................102









5.2.4 Prediction of Compressive Strength Development ................... ............... 103
5.3 Analysis of Splitting Tensile Strength Test Results ........................................ ............105
5.3.1 Effects of Water to Cement Ratio on Splitting Tensile Strength .........................105
5.3.2 Effects of Coarse Aggregate Type on Splitting Tensile Strength ......................105
5.3.3 Effects of Fly Ash and Slag on Splitting Tensile Strength of Concrete.............13
5.4 Relationship between Compressive Strength and Splitting Tensile Strength ..............114
5.5 Analysis of Elastic M odulus Test Results ................................. ..... ............... 117
5.6 Relationship between Compressive Strength and Elastic Modulus .............................120
5.7 Sum m ary of F findings ........................................................................... ....................122

6 ANALYSIS OF SHRINKAGE TEST RESULTS .................................... ............... 127

6 .1 In tro d u ctio n ................................ ............................................................................... 12 7
6.2 Results and Analysis of Shrinkage Tests.............. ........ ... .. ...............127
6.2.1 Effects of Curing Conditions on Shrinkage Behavior of Concrete .......... ......127
6.2.2 Effects of Mineral Additives on Shrinkage Behavior ............... ...................129
6.2.3 Effects of Water Content on Shrinkage Behavior .................... ... .............130
6.2.4 Effects of Aggregate Types on Shrinkage Behavior................... ...................131
6.2.5 Relationship between Compressive Strength and Shrinkage Strain...................133
6.2.6 Relationship between Elastic Modulus and Shrinkage Strain.............................135
6.3 Evaluation on Shrinkage Prediction M models ...................................... ............... 137
6.3.1 ACI-209 m odel ............. .. ........ ... ... ................. ..... ......... 137
6.3.2 CEB -FIP M odel ......... .. .......................... ........ ..... .... .......... ............ 138
6.4 Prediction of Ultimate Shrinkage Strain................................... ...............140
6.4.1 Least Square Method of Curve-fitting...... ................. ............141
6.4.2 Evaluation Methods on the Goodness of Fit ............. ...... ...............142
6.4.3 Predicted R results ........ ...... .............................. ...... .. ........ .... 145
6.5 Sum m ary of F findings ........................................................................... ....................146

7 ANALYSIS OF CREEP TEST RESULTS ........................................ ...................... 148

7.1 Introduction ........... ....................... ......... .......................148
7.2 Analysis of Creep Test Results.................................................................. ............... 148
7.2.1 Effects of Curing Conditions on Creep Behavior of Concrete..........................148
7.2.2 Effects of Loading Condition on Creep Behavior of Concrete............................ 151
7.2.3 Effects of Aggregate Types on Creep Behavior of Concrete .............................153
7.2.5 Effects of Water to Cement Ratio and Air Content on Creep Strain..................156
7.2.6 Relationship between Compressive Strength and Creep Strain .........................157
7.3 Creep Coefficient............................. ...... .......... ...... ...... .......... 163
7.3.1 Effects of Loading Conditions on Creep Coefficient ................ ................163
7.3.2 Effects of Curing Conditions on Creep Coefficient ............................................163
7.3.3 Effects of Water Content on Creep Coefficient .................................. ..............165
7.3.4 Effects of Compressive Strength at Loading Age on Creep Coefficient............166
7.3.5 Relationship between Elastic Modulus at Loading Age and Creep Coefficient..169
7.3.6 Effects of Coarse Aggregate Type on Creep Coefficient................................171
7.4 C reep M odulu s......................................................... ...................................... .... 172
7.5 Prediction of U ltim ate Creep Strain ........................................ .......................... 174









7.6 Evaluation on Creep Prediction M odels................................ ................................. 175
7.7 Sum m ary of F findings ........................................................................... ....................186

8 CONCLUSIONS AND RECOMMENDATIONS .................................... ............... 188

8.1 D design of C reep A pparatu s............................................................................................. 188
8.2 F findings from T his Study ............................................................... .......................188
8.2.1 Strength and Elastic M odulus............... .. ...................... ............... ....188
8.2.2 Shrinkage Characteristics of Concretes Investigated ........................................190
8.2.3 Creep Characteristics of Concretes Investigated...............................................191
8.3 R ecom m endations...... .......... .................................... .. ............ .. ........... 192

APPENDIX

A MEASUREMENTS FROM STRENGTH TESTS................................... .....................193

B MEASURED AND CALCULATED RESULTS FROM CREEP TESTS .......................... 199

L IST O F R E F E R E N C E S .................................................................................. .....................2 12

B IO G R A PH IC A L SK E T C H ............................................................................. ....................2 18









LIST OF TABLES


Table page

3-1 Mix proportions of the 14 concrete mixtures involved in this study .............................61

3-2 Physical properties of Type I cem ent....................................................... .............. 62

3-3 Chem ical ingredients of Type I cem ent...................................... .................. ......... 62

3-4 Physical and chemical properties of fly ash.......................... .............................. 62

3-5 Physical and chem ical properties of slag................................................ ........ ....... 62

3-6 Physical properties of fine aggregate........................................................... ............... 62

3-7 Physical properties of coarse aggregates ........................................ ....................... 62

3-8 The testing programs on fresh concrete.............................. ............................... 67

3-9 P properties of fresh concrete ...................................................................... ................ .....68

3-10 The testing program on hardened concrete.......................... ............................... 69

5-1 Compressive strength of the concrete mixtures evaluated.........................................95

5-2 Comparison of the accuracy between ACI equation and Modified ACI Equation.......... 106

5-3 Regression analysis on the prediction of compressive strength of concrete....................107

5-4 Values of the constants,a, 3 and c/l and the time ratio ....... ...................................108

5-5 Splitting tensile strengths of the concrete mixtures evaluated .............. ... ...............109

5-6 Regression analysis for relating compressive strength to splitting tensile strength......... 115

5-7 Elastic module of the concrete mixtures evaluated..................................... ................. 117

5-8 Regression analysis using the expression recommended by ACI 318-89 .......................123

5-9 Regression analysis on ACI 318-95 equation with forcing it through origin point.........123

5-10 Regression analysis using the expression recommended by ACI 318-95 .....................125

6-1 Shrinkage strains of the concrete mixtures evaluated at various curing ages ................128

6-2 Regression analysis on relationship of compressive strength to shrinkage strain ..........135

6-3 Regression analysis on relationship of elastic modulus to shrinkage strain.................... 136









6-4 Correction factors for the ACI 209 model on shrinkage prediction .............................138

6-5 R egression analy sis results ...................................................................... ..................146

7-1 Regression analysis on relationship between compressive strength and creep strain .....160

7-2 Regression analysis on relationship of compressive strength to creep coefficient ..........167

7-3 Regression analysis on relationship of elastic modulus to creep coefficient...................171

7-4 Regression analysis on relation of creep coefficient to fE/E ................... ............... 171

7-5 The predicted ultimate creep strain and creep coefficient ........................................175

7-6 Regression analysis on relation of creep coefficient to fE/E ................... ............... 182

7-7 Correction factors for the ACI 209 model ............................................ ............... 185

A-1 Results of compressive strength tests ....... ...............................................................194

A-2 Normalized compressive strength development characteristics of the concrete
m fixtures evaluated .......................................... ............................. ....195

A -3 Results of splitting tensile strength tests................................................... ......... ...... 196

A-4 Normalized Splitting tensile strength development characteristics of the concrete
m fixtures evaluated .......................................... ................... .. ...... .... 197

A-5 Results of elastic m odulus tests ......................................................................... 198

B-l M measured and calculated results from creep tests ....................................... .................200









LIST OF FIGURES


Figure page

2-1 Representation of the stress-strain relation for concrete...................... ..................27

2-2 Stress-strain relations for cement paste, aggregate and concrete.................. ............29

2-3 Effect of coarse aggregate content on the shrinkage of concrete.................. ............37

2-4 Creep diagram of concrete m material ....................................................... ............... 47

2-5 Strain-time plot of concrete under a sustained load and after release of load ...................48

3-1 Gradation of fine aggregate (Godenhead sand) ................. ............................63

3-2 Gradation of coarse aggregate (Miami Oolite limestone)..........................................63

3-3 Gradation of coarse aggregate (Georgia granite)........................................64

3-4 Gradation of lightweight aggregate (Stalite)................................................................... 64

3-5 C om pulsive P an M ixer ............................................................................ ....................65

3-6 Typical failure model of concrete cylinder in compression test................... ..............70

3-7 Loading configuration for splitting tensile test...... ....................... ............71

3-8 MTS system for elastic modulus and compressive strength test .......................................73

3-9 Cylindrical specimen with gage point installed...... ....................... ...........74

4-1 Creep test apparatus ........... .. .................................... ....................... 78

4-2 Boundary conditions used for finite element analysis...................................................79

4-3 M esh plot of H leader plate analysis.......... ................. ........................ ............... 80

4-4 Contour plot of deflection of header plate............................... ...................80

4-5 Design of Gage-point positioning guide.................................................. ............... 83

4-6 Gauge position guide ............................................ ........................ 84

4-7 Plastic cylindrical mold inside gauge position guide............................................. 84

4-8 Schematic of Alignment Frame Design............... ........... .......................87

4-9 M mechanical gauge ..................................... .. ... ... .. .................. 88









4-10 Positioning springs on the bottom plate....................................... .......................... 88

4-12 Concrete cylinder with both end surfaces ground.................................. ............... 89

4-13 How to center the specimens into creep frame ...................................... ............... 90

4-14 How to center the hydraulic jack cylinder............................ ...... .................91

4-15 Leveling the plate on the top of load cell.......................... ..................... ............ 91

5-1 Effect of water to cementitious materials ratio on compressive strength at 28 days.........96

5-2 Effect of water to cementitious materials on compressive strength at 91 days .................97

5-3 Effect of water content on compressive strength at 28 days ................ ......... ..........97

5-4 Effect of water content on compressive strength at 91 days..............................................98

5-5 Effect of coarse aggregate type on compressive strengths of Mix-2F and Mix-2GF......100

5-6 Effect of coarse aggregate type on compressive strength of Mix-3F and Mix-3GF .......100

5-7 Effect of coarse aggregate type on compressive strength of Mix-5S and Mix-5GS .......101

5-8 Effect of coarse aggregate type on compressive strength of Mix-7S and Mix-7GS .......101

5-9 Effect of fly ash and slag on compressive strength of concrete ............... ...............102

5-10 Effect of water to cement ratio on splitting tensile strength at 28 days........................... 109

5-11 Effect of water to cement ratio on splitting tensile strength at 91 days ...........................110

5-12 Effect of aggregate type on splitting tensile strength of Mix-2F and Mix-2GF ..............111

5-13 Effect of aggregate type on splitting tensile strength of Mix-3F and Mix-3GF ..............111

5-14 Effect of aggregate type on splitting tensile strength of Mix-5S and Mix-5GS ..............112

5-15 Effect of aggregate type on splitting tensile strength of Mix-7S and Mix-7GS ..............112

5-16 Effect of fly ash and slag on splitting tensile strength of concrete ..................................114

5-17 Relationship between compressive strength and splitting tensile strength ......................116

5-18 Effect of coarse aggregate type on modulus of elasticity of Mix-2F and Mix-2GF........ 118

5-19 Effect of coarse aggregate type on modulus of elasticity of Mix-3F and Mix-3GF........119

5-20 Effect of coarse aggregate type on modulus of elasticity of Mix-5S and Mix-5GS........ 119









5-21 Effect of coarse aggregate type on modulus of elasticity of Mix-7S and Mix-7GS........120

5-22 Relationship between compressive strength and elastic modulus based on ACI Code...124

5-23 Plot of elastic modulus against w 1f' for all curing conditions............... .................124

6-1 Effect of curing condition on shrinkage strain of concrete mixtures at 91 days............130

6-2 Effect of water content on shrinkage strain at 91 days............. ....................................131

6-3 Effect of water to cementitious materials ratio on shrinkage strain at 91 days .............132

6-4 Effect of coarse aggregate type on shrinkage behavior of concrete .............................133

6-5 Relationship between compressive strength and shrinkage strain at 91 days................135

6-6 Relationship between shrinkage strain at 91 days and modulus of elasticity ................36

6-7 Comparison between the shrinkage strain at 91 days and the shrinkage strain
calculated by ACI 209 model and C.E.B-F.I.P model...............................................140

6-8 Comparison among the ultimate shrinkage strains from curve-fitting, CEB-FIP
m odel and A C I 209 m odel ......................................................................... ................ 14 5

7-1 Effect of curing condition on creep of concrete loaded at 40% of compressive
strength ................... ......................................................................... 150

7-2 Effect of curing condition on creep of concrete loaded at 50% of compressive
strength ................... ......................................................................... 150

7-3 Effect of stress level on creep of concrete moist-cured for 7 days...............................152

7-4 Effect of stress level on creep of concrete moist-cured for 14 days..............................153

7-5 Effect of aggregate type on creep behavior of Mix-2F....... ......................................154

7-6 Effect of aggregate type on creep behavior of Mix-3F ..............................................155

7-7 Effect of aggregate type on creep behavior of Mix-5S ............. .... ...............155

7-8 Effect of aggregate type on creep behavior of Mix-7S............. .... ...............156

7-9 Effect of water to cementitious materials ratio and air content on creep of concrete
moist-cured for 7 days and loaded at 40% of compressive strength..............................158

7-10 Effect of water to cementitious materials ratio and air content on creep of concrete
moist-cured for 7 days and loaded at 50% of compressive strength..............................159









7-11 Effect of water to cementitious materials ratio and air content on creep of concrete
moist-cured for 14 days and loaded at 40% of compressive strength..............................159

7-12 Effect of water to cementitious materials ratio and air content on creep of concrete
moist-cured for 14 days and loaded at 50% of compressive strength ..............................160

7-13 Relationship between compressive strength and creep strain of concrete moist-cured
fo r 7 d ay s ...................................................................................... 16 1

7-14 Relationship between compressive strength and creep strain of concrete moist-cured
fo r 14 d ay s .................................................................................... 16 1

7-15 Relationship between compressive strength and creep strain of concrete under all
cu ring con edition s............................. ...................................................... ............... 162

7-16 Relationship of compressive strength to instantaneous strain measured in creep test.....162

7-17 Effect of stress level on creep coefficient of concrete moist-cured for 7 days..............164

7-18 Effect of stress level on creep coefficient of concrete moist-cured for 14 days............164

7-19 Effect of curing condition on creep coefficient of concrete .................................. 165

7-20 Effect of water content on creep coefficient at 91 days............................166

7-21 Relationship between compressive strength and creep coefficient for specimens
loaded at 14 day s ........................................................................ 16 8

7-22 Relationship between compressive strength and creep coefficient for specimens
loaded at 2 8 day s ........................................................................ 169

7-23 Relationship between compressive strength at loading age and corresponding creep
coefficient at 91 days ................................ .... .......................... 169

7-24 Effect of Elastic modulus at loading age on creep coefficient at 91 days .................... 170

7-25 Relationship between creep coefficient at 91 days and fo/E ....................... ...............171

7-26 Effect of coarse aggregate type on creep coefficient at 91 days................................... 172

7-27 Typical decay curve of creep modulus with time .......................................................173

7-28 B ehaviors of a B urgers M odel ............................................................................ ... 176

7-29 Evaluation on creep prediction m odels....................................... ......................... 178

7-30 Comparison on the effectiveness of C.E.B-F.I.P model and ACI model ......................180









7-31 Comparison between the creep strain at 91 days from experimental data and the
predicted creep strain using CEB-FIP model..................................... ......... ............... 181

7-32 Relationship between creep strain and mechanical properties at loading age...............82

7-33 Comparison between the ultimate creep strain calculated by C.E.B-F.I.P model and
that by curve-fitting ....... .......................................................................... ...... ... .... 183

7-34 Evaluation on ACI-209 model and C.E.B-F.I.P model ......................................... 185









Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

STRENGTH, MODULUS OF ELASTICITY, SHRINKAGE AND CREEP OF CONCRETE

By

Yanjun Liu

December 2007

Chair: Mang Tia
Cochair: Renaldo Roque
Major: Civil Engineering

In the application of prestressed concrete, there are concerns on severe prestress loss

caused mainly by elastic shortening, shrinkage and creep of concrete, which will result in the

extreme reduction of the design capacity of prestressed concrete structure, or even the premature

structure failure. Hence, the values of elastic modulus, ultimate shrinkage strain, and ultimate

creep coefficient of concrete have to be estimated reasonably and accurately at the production

stage in order to avoid loss of structural capacity, or even unexpected structural failure caused by

prestress loss.

At present, the modulus of elasticity, shrinkage and creep properties of concrete that are

used in structural design are either based on the arbitrary available literature or based on the

limited research of the locally available materials. Thus, there is a great need for a

comprehensive testing and evaluation of locally available concrete mixes to determine their

mechanical and physical properties so that correct values for these properties can be used in

structural design. Also, there is a great need to design a simple, effective, practical and reliable

creep apparatus to carry this massive investigation on creep behavior of concrete out.

In this study, a creep test apparatus was designed, and twenty four creep apparatus were

constructed for use in performing creep tests. The creep apparatus was evaluated to be working









satisfactorily. An effective creep testing procedure was developed and documented. Also, a

gauge point position guide was designed for installing gauge point on the cylindrical mold and it

was proved to be an effective tool in preparation of specimens for creep tests. In addition, an

alignment frame was designed and it was proved to be a very useful tool to ensure that the

specimens can be set up in the creep apparatus vertically.

In this study, 14 concrete mixtures were evaluated, and replicate batches for ten of these

mixes were also produced and evaluated. Three types of coarse aggregate, fly ash and ground

blast-furnace slag were incorporated in the mix designs in this study. Concrete specimens were

fabricated and tested for their compressive strength, splitting tensile strength, elastic modulus,

shrinkage and creep. This study has generated valuable data and determined general trends on

the compressive strength, splitting tensile strength, elastic modulus, drying shrinkage strains and

creep coefficient of structural concretes investigated in this study. Most importantly, the inter-

relationships among compressive strength, elastic modulus and shrinkage and creep properties of

concrete were found through regression analysis. These relationships make the predictions of

shrinkage and creep possible with the information from compressive strength and elastic

modulus.









CHAPTER 1
INTRODUCTION

1.1 Background and Research Needs

Prestressed concrete structures, such as prestressed girder for long-span bridge, prestressed

shell concrete structure for the storage of water or gas, nuclear reactor vessels and offshore oil

drilling platforms so on, are widely used in the U.S as well as other countries in the world. This

is attributed mainly to the advantages of prestressed concrete structure, which include)

eliminating or considerably reducing the net tensile stresses caused by load, 2) increasing the

capacity of the structure, and 3) decreasing the self-weight of concrete members. Also,

prestressed concrete element is slimmer than reinforced concrete and more pleasing aesthetically.

In the application of prestressed concrete, there are concerns on severe prestress loss

caused mainly by elastic shortening, shrinkage and creep of concrete. Consequently, the design

capacity of prestressed concrete structure will be extremely reduced, or even the structure will

fail prematurely. Hence, the values of elastic modulus, ultimate shrinkage strain, and ultimate

creep coefficient of concrete have to be estimated reasonably and accurately at the production

stage in order to avoid loss of structural capacity, or even unexpected structural failure caused by

prestress loss.

For the sake of avoiding unexpected prestress loss, the strict requirements on shrinkage

and creep properties of the concrete used for prestressed concrete structures have been specified

by ACI Code as well as other Specifications. For example, the "AASHTO LRFD Bridge

Construction Specifications-2001 Interim Revisions" [AASHTO, 2001] specifies that, for the

design of continuous prestressed concrete I-girder superstructures, the ultimate creep coefficient

should be 2.0 and the ultimate shrinkage strain will take the value of 0.0004, in accordance with

the recommendation of ACI 209. The Specification also states that, when specific data are not









available, estimates of shrinkage and creep may be made using the provisions of CEB-FIP model

or ACI 209 model.

The creep behavior of concrete has been the focus of engineer's attention and may still be

the engineer's concentration for decades to come because of the volatility of the creep property

of concrete. Over the years, many attempts have been tried to develop the general constitutive

equation for the description of time-dependent behavior of concrete. However, most of them are

empirical in nature and are limited to the scopes of the experiments. There are great uncertainties

in extrapolation to later times and to the conditions not covered in the laboratory. AASHTO

LRFD Specifications state the following: "without results from tests on the specific concretes or

prior experience with the materials, the use of the creep and shrinkage values referenced in these

Specifications can not be expected to yield results with errors less than +50%."

The values of the modulus of elasticity, ultimate shrinkage strain and ultimate creep

coefficient of concrete, which are used in structural design in Florida, are either based on the

arbitrary available literature or based on the limited research of the locally available material.

Particularly, since very limited creep testing has been performed on Florida concretes, the

knowledge of creep characteristics of Florida concrete is still a blind page. More importantly,

the susceptibility of the elastic modulus, shrinkage and creep of concrete to the variation of

concrete mix ingredients, such as particular aggregates in Florida, water content and mineral

additives so on, puts more uncertainties in using these values.

There is a great need for a comprehensive testing and evaluation of locally available

concrete mixes to determine these mechanical and physical properties of Florida normal-weight

as well as lightweight concretes, especially for the concretes used in pre-stressed concrete

structure, so that correct values for these properties can be used in structural design. In addition,









there is also an immediate need to determine the most effective and practical laboratory test

setups and procedures for obtaining the modulus of elasticity, creep and shrinkage properties of

structural concretes used in Florida. This research study was carried out to meet these needs of

the FDOT.

1.2 Hypothesis

* Creep is related other mechanical properties of concrete, especially strength and elastic
modulus. Thus, it is possible to estimate or predict its creep behavior based on the
knowledge of its other mechanical properties.

* Shrinkage of concrete is related to its water content and other mechanical properties,
specially strength and elastic modulus. Thus, it is possible to estimate shrinkage behavior
from its water content and other mechanical properties.

* Ultimate creep coefficient of concrete may exceed a value of 2.0, which is usually assumed
to be the maximum value in structure design. Thus, creep testing on the specific concrete is
needed to obtain reliable value of its ultimate creep coefficient.

1.3 Objectives of Study

This research has the following major objectives:

* To design and recommend an effective and reliable laboratory testing set-up and procedure
for performing creep tests on concrete.

* To evaluate the effects of aggregate, mineral additives and water to cementitious materials
ratio on strength, elastic modulus, shrinkage and creep behavior of concrete.

* To determine the strength, elastic modulus, shrinkage and creep behavior of the typical
concretes used in Florida.

* To determine the relationship among compressive strength, splitting tensile strength and
modulus of elasticity of concretes made with typical Florida aggregate.

* To develop prediction equations or models for estimation of shrinkage and creep
characteristics of typical Florida concretes.

1.4 Scope of Study
The scope of this research covered the following major tasks:

* To review the literature about previous and current study on elastic modulus, shrinkage
and creep of concrete.









* To design, construct and evaluate the effectiveness of creep test set-up and procedures.

* To perform a comprehensive laboratory study on the physical and mechanical properties
of typical Class II, IV, V and VI concrete mixtures made with normal weight aggregate
and lightweight aggregate, including compressive strength, indirect tensile strength,
modulus of elasticity, creep and shrinkage behavior. A total of 14 different concrete mixes
was evaluated, and ten of them were replicated.

* To analyze the experimental data, and to determine the relationships among different
properties, and to develop prediction equations for estimation of shrinkage and creep
behaviors of concrete.

1.5 Research Approach
Objectives of this study are realized by the following research approaches:

* Conduct laboratory testing programs to determine the various properties of concrete.
ASTM standard test methods were used for compressive strength test, splitting tensile test,
elastic modulus test and shrinkage test. A creep test set-up was designed, evaluated and
refined to be used for this purpose.

* Perform statistical analysis to determine relationships and trends among the fundamental
properties of the concretes evaluated in this study.

* Evaluate existing prediction models for creep and shrinkage and develop improved models
for estimation of shrinkage and creep behaviors of concrete.









CHAPTER 2
LITERATURE REVIEW

2.1 Introduction

The following content presents a literature review on the susceptibility of strength, elastic

modulus, shrinkage and creep properties of concrete to various factors, and on the existing

models for predicting the strength, elastic modulus, and shrinkage and creep properties of

concrete.

2.2 Strength of Concrete

2.2.1 Significance of Studying Strength of Concrete

Strength is commonly considered as the most valuable property of concrete, and it gives an

overall picture of the quality of concrete because of its direct relation to the micro-structure of

the hydrated cement paste. Moreover, the strength of concrete is almost invariably a vital

element of structural design and is specified for compliance purpose. Also, knowing strength

development characteristic of concrete is very critical in decision-making about when to remove

formworks, when to continue next construction step, or when to open structure to service.

Apparently, the economic analyzer will be very pleased for knowing the aforementioned

information to optimize project budget.

Over the past decades, with the broad development and application of new concrete

technique characterized by high strength concrete and high performance concrete, durable

concrete structure and complex structural design become realizable. For example, high-rise

building enables humankind to make full use of limit living space on this planet plausible; and

long-span bridge are more pleasing aesthetically, cost-effective and resource-saving.

However, even though a large amount of information has been accumulated about concrete

strength design, engineers are still fore from knowing well the strength properties of concrete. To









design a concrete mixture with preassigned properties is still an engineer's dream. The causes are

attributed to the volatility of concrete strength induced by the variation of raw materials and their

proportions. Thus, the properties of concrete materials are still worthy of study.

2.2.2 Effect of Coarse Aggregate on Strength of Concrete

The investigation on the effect of raw materials and their proportions on strength

development has been the focus of many engineers' effort.

For example, Aitcin and Mehta [Aitcin, P-C and Mehta, P. K, 1990] studied the effect of

coarse aggregate characteristics on mechanical properties of high strength concrete. The

experiment was carried out using four coarse aggregate types available in Northern California

and similar mix proportions. The results showed that using diabase and limestone aggregates

produced concretes with significantly higher strength and elastic modulus than those using

granite and river gravel. They concluded that the mineralogical differences in the aggregate types

were responsible for this behavior.

Sarkar and Aitcin [Sarkar, S. L and Aitcin, P-C, 1990] carried out research on the

importance of petrological, petrographical and mineralogical characteristics of aggregate in very

high strength concrete. They pointed out that aggregate intrinsic strength, particularly that of

coarse aggregates, receives scant attention from concrete technologists and researchers as long as

the w/c ratio falls within the 0.50-to-0.70 range, primarily due to the fact that the cement-

aggregate bond or the hydrated cement paste fails long before aggregates do. This, however,

does not hold true for very high-strength concretes, with very low w/c ratios of 0.20 to 0.30.

Compressive strength testing of very high-strength concrete has indicated that aggregates can

assume the weaker role, exhibited in the form of transgranular fractures on the surface of failure,

as has already been observed in some lightweight concretes. The authors have carried out

detailed petrological, petrographical and mineralogical characterization of twelve different









coarse aggregates that have performed with variable success in very high-strength concrete in

Canada and the United States. Suitability for such an application has been linked to a special set

oflithological characteristics: the minerals must be strong, unaltered, and fine grained. Intra- and

intergranular fissures partially decomposed coarse-grained minerals, and the presence of

cleavages and lamination planes tend to weaken the aggregate, and therefore the ultimate

strength of the concrete.

Ezeldin and Aitcin [Ezeldin, A. S. and Aitcin, P-C, 1991] studied the effect of four coarse

aggregates with different characteristics on the compressive strength, flexural strength, and

flexural strength/compressive strength ratio of normal- and high-strength concretes. The study

investigated the possibility of obtaining a relatively high flexural strength/compressive strength

ratio at high compressive strength by using different aggregate types.

The study by Alexander and Addis [Alexander, M. G. and Addis, B. J., 1992] showed that

aggregates play an important role in governing mechanical properties of high strength concrete.

Generally, andesite and dolomite aggregates give superior results. Tests were also done on

"artificial" interfaces between paste and these two rock types in order to characterize the

interfacial bond properties. Results show that andesite achieves higher interfacial fracture energy

values than dolomite, which helps to confirm the macroscopic engineering properties measured

on concretes.

Giaccio, Rocco, Violini, Zappitelli, and Zerbino [Giaccio, G. et al, 1992] pointed out that

concrete is a heterogeneous material whose properties depend on the properties of its component

phases and the interactions between them. They studied the effects of granitic, basaltic, and

calcareous aggregates on the mechanical properties of high strength concrete, including

compressive strength, flexural strength, modulus of elasticity and stress-strain behavior of









concrete. The results indicated that the effect of coarse aggregate characteristics on the

mechanical properties of high-strength concretes is substantial.

The impact of aggregate strength on concrete compressive strength was evaluated by

Lindgard, and Smeplass [Lindgard, J. and Smeplass, S, 1993] as well. The significance of the

aggregate strength has been compared with the effect of the cement type and the use of silica

fume. According to the obtained results, the impact of the aggregate strength on the strength of

high strength concrete is limited, compared with the impact of the binder type, while the

differences in elastic modulus between the different aggregate types is fully reflected in the

concrete elastic modulus. This contradiction is explained by a hypothesis based on stress

concentrations due to the difference in rigidity between the binder and the aggregates.

2.2.3 Prediction of Strength of Concrete

If there is no specific testing data available, it is a good alternative to have an equation

reliable to give an effective prediction on the strength of concrete at desired age. An accurate

approximation to the strength of concrete at specific ages is of great importance to know in order

to decide on when to remove formwork, when to continue next construction step, and when to

open the structure into service.

In analyzing the characteristics of development of compressive strength with time, an

empirical equation has been provided by ACI 209R Code as follows:

f() = f (2-1)
c a+(t -t c28
Where a in days and / are constants, f28 is compressive strength of concrete at 28 days,

and t in days is the age of concrete. For the tests using 6"x 12" cylinder, type I cement and moist

curing condition, two constants, a and /, are equal to 4.0 and 0.85 respectively.









Because of substantial effect of coarse aggregate type on the properties of concrete, and

because of no such mineral additives as fly ash and slag involved, which have substantial effects

on the development of concrete strength, when the aforementioned formula was developed,

caution should be taken when it is used. If possible, further investigation should be carried out to

calibrate the above equation.

2.3 Elastic Modulus of Concrete

2.3.1 Definition and Determination of Elastic Modulus of Concrete

The modulus of elasticity or "Young's Modulus", a very important mechanical property

reflecting the capability of concrete to deform elastically, is defined as the slope of the stress-

strain curve within the proportional limit of a material.




Initial tangent Tangent__
modulus 7



Loading V/-
Loadi Unloading
Secant
modulus




Strain


Figure 2-1 Representation of the stress-strain relation for concrete

For a concrete material, usually, the most commonly used value in structure design is the

secant modulus, which is defined as the slope of the straight line drawn from the origin of axes to

the stress-strain curve at some percentage of the ultimate strength. Since no portion of the stress-

strain curve is a straight line, the usual method of determining the modulus of elasticity is to

measure the tangent modulus, which is defined as the slope of the tangent to the stress-strain









curve at some percentage of the ultimate strength of the concrete as determined by compression

tests on 6"x 12" cylinders. Figure 2-1 illustrates the stress-strain plot of a concrete as it is loaded

and unloaded. From this figure, we can see that the secant modulus is almost identical to the

tangent modulus obtained at some lower percentage of the ultimate strength.

2.3.2 Significance of Studying Elastic Modulus of Concrete

Concrete, as a building material, is utilized in the elastic range. Thus, it is very important

to know the relationship between stress and strain for a given concrete before it can be used for

buildings, bridges, pavement and so forth. The relationship between stress and strain for a

concrete material can be characterized by its elastic modulus, which is the property of concrete

materials.

For reinforced concrete structures, the knowledge of the elastic property of a specific

concrete will not only make the deformation of the concrete members well-controlled, but also

decrease the extra stress transfer to other concrete elements, which can cause the concrete to

crack or fail prematurely.

For prestressed concrete structures, elastic shortening is blamed for causing prestress loss.

The prestress loss, on one hand, will decrease the capacity of a concrete structure, and even lead

to unexpected collapse of the structure; and on the another hand, it will results in the increased

volume of tendon for satisfying the design requirement because of over-estimation on elastic

shortening, which can result in possible waste of materials and increased cost.

In addition, in order to make full use of the compressive strength potential, the structures

using high-strength concrete tend to be slimmer and require a higher elastic modulus to maintain

its stiffness. Therefore, the knowledge of the elastic modulus of high strength concrete is very

important in avoiding excessive deformation, providing satisfactory serviceability, and achieving

the most cost-effective designs.










At last, for concrete pavement, high elastic modulus concrete is not desirable because it

increases the pavement cracking probability. Thus, high strength but low modulus concrete is

preferable. As to how to obtain the concrete material with the properties desired, one way to

approach this goal is to change the properties of individual concrete components and their

proportions. And most importantly, the significant effects of different types of coarse aggregate

on elastic modulus of concrete have to be investigated.

2.3.3 Effect of Coarse Aggregate on Elastic Modulus of Concrete



50
50 Aggregate
40

Concrete
U 30

20 Cement paste


10



0 1000 2000 3000

Strain -10-6


Figure 2-2 Stress-strain relations for cement paste, aggregate and concrete

Since concrete is a multiphase material, modulus of elasticity is very susceptible to the

variation of coarse aggregate content and coarse aggregate type. In a study by Stock, Hannant

and Williams [Stock et al, 1979], it was reported that for concretes with a fixed w/c of 0.5, as the

volume of coarse aggregate varied from 20 to 60 %, the compressive strength of concrete

remained almost same. This result is very consistent with the 'W/C law' established by Duff

Abrams in 1919. That is to say, for a given mix proportion, the compressive strength of concrete









will be determined by its water to cement ratio. This is especially true for normal concrete with

compressive strength less than 60MPa. However, the elastic modulus of the concrete was

substantially influenced by the changes in its coarse aggregate content. As shown in Figure 2-2

[A.M.Neville, 1996], we can see that the elastic modulus of concrete is remarkably different

from that of hardened cement paste. Also, Neville [A.M.Neville, 1996] pointed out that, for a

concrete of a given strength, because normal weight aggregate has a higher elastic modulus than

hydrated cement paste, a higher aggregate content results in a higher modulus of elasticity of the

concrete.

In a study by Persson [Persson, 2001], it was reported that the elastic modulus of self-

compacting concrete was the same as that for normal concrete as long as their compressive

strengths were the same. However, in the study by Schlumpf [Schlumpf, 2004], the elastic

modulus of self-compacting concrete was reported to be 20% lower than that of a normal

concrete with similar strength. In addition, the findings from the study by Chi [Chi, 2003] also

indicated that the aggregate fraction in concrete had a considerable effect on the elastic modulus

of concrete.

Coarse aggregate type is another very important factor affecting the elastic modulus of

hardened concrete. Different types of aggregate can have quite distinct effects on elastic

modulus. Even different coarse aggregates of the same type but from different locations can

have substantially different properties. The reported findings by Zhou, Lydon and Barr [Zhou et

al, 1995] show that the coarse aggregate type has a considerable influence on the elastic modulus

of concrete. In their study, the effects of expanded clay, sintered fly ash, limestone, gravel, glass

and steel aggregate on the elastic modulus of concrete were investigated. In addition, the study









by Shideler [Shideler, 1957] on concrete mixtures using gravel and expanded clay as aggregate

also indicate the same conclusion as reported by Zhou, Lydon and Barr [Zhou et al, 1995].

In 1990, Aitcin and Mehta [P. C. Aitcin and P. K. Mehta, 1990] also investigated the effect

of coarse aggregate characteristics on mechanical properties of high strength concrete. In their

study, the influence of four coarse-aggregate types available in Northern California on the

compressive strength and elastic behavior of a very high strength concrete mixture was studied

using identical materials and similar mix proportions. The results indicated that the diabase and

limestone aggregates were found to produce concretes with significantly higher strength and

elastic modulus than did the granite and river gravel. The mineralogical differences in the

aggregate types are considered to be responsible for this behavior.

The study by Alexander [Mark G. Alexander, 1996] on the influence of 23 different

aggregate types on the properties of hardened concrete showed that aggregates exert a profound

and important influence on the elastic property of concrete.

In 1998, Cetin and Carrasquillo [Aykut Cetin and Ramon L. Carrasquillo, 1998] carried

out an investigation on the effects of four coarse aggregate types locally available in central

Texas on the mechanical properties of high-performance concrete. Test results showed that the

mineralogical characteristics of coarse aggregate as well as the aggregate shape, surface texture,

and hardness appeared to be responsible for the differences in the performance of high

performance concretes. Also, it was observed that it appeared that there was no one single

equation for high-performance concrete mixtures with different coarse aggregates that coulc

estimate the elastic modulus with sufficient accuracy as in the case of normal strength concretes.

Wu, Chen amd Yao [Wu K.-R, Chen B, Yao W, Zhang D, 2001] carried out a study on the

effects of the coarse aggregate type, including crushed quartzite, crushed granite, limestone, and









marble coarse aggregate, on the compressive strength, splitting tensile strength, fracture energy,

characteristic length, and elastic modulus of concrete. The results indicated that the stiffness of

concrete depends on the type of aggregate, especially for high-strength concrete.

Beshr and Maslehuddin [Beshr H et al, 2003], Rashid, Mansur and Paramasivam [M. A.

Rashid et al, 2002]; Huo, Al-Omaishi and Tadros [Xiaoming Sharon Huo et al, 2001] reported

that different types of coarse aggregate have pronounced effects on elastic modulus of concrete.

2.3.4 Models for Predicting Elastic Modulus of Concrete

As mentioned in the literature about the factors affecting elastic modulus of concrete, for a

given type of aggregate, although the modulus of elasticity of concrete will increase with the

strength of concrete, the factors that affect the modulus of elasticity of concrete do not always

have a corresponding effect on the strength of concrete. Thus, there is no universal equation that

can be possibly applied to relate compressive strength to elastic modulus of concrete. Thus, the

models, both ACI model and CEB-FIP model, may need to be modified in order to be applied to

a structure to achieve full function and serviceability in its entire life span. The above hypothesis

can be easily confirmed by an extensive testing program to investigate the effects of coarse

aggregate types on elastic modulus of concrete.

The study by Shih, Lee, and Chang [Shih, T. S. et al, 1989] suggested that Young's

modulus of high-strength concrete has a somewhat higher value than that of normal-strength

concrete. Pauw's equation for modulus of elasticity of concrete, which is based on experimental

normal-strength concrete, needs to be reexamined.

Baalbaki, Benmokrane, Chaallal, and Aitcin, [Baalbaki, W., 1991] studied the influence of

different types of crushed rocks on elastic properties of high performance concrete. Testing

results pointed to the important role played by coarse aggregates through the elastic properties of









the parent rock. They also recommended that the present formulas relating the prediction of

elastic modulus of concrete recommended by some codes should be reviewed.

Nilsen and Aitcin [Nilsen, A. U. and Aitcin, P-C., 1992] investigated the properties of high

strength concrete containing lightweight, normal weight and heavyweight aggregates. In this

study, a comparison of the values of elastic modulus determined experimentally with those

calculated according to the formula recommended by the ACI Building Code, the British

Standard Code, and the Norwegian Standard Code, showed that all codes overestimated the

elastic modulus of high-strength heavyweight concrete.

In the following section, the formula used to predict the elastic modulus of concrete by

Florida LRFD Guidelines, ACI model, and CEB-FIP model are given.

* Model recommended by Florida LRFD Guidelines [2002]

According to this guideline, in the absence of more precise data, the modulus of elasticity

for concretes with unit weights between 0.090 and 0.155 kcf, can be estimated from the

following formula:


E =a-.w .f- (2-2)
C C C (2
Where

E,- Elastic modulus in ksi.

wc -Unit weight of concrete (kcf).

fc -Compressive strength of concrete (ksi).

a -Constant, a = 33000 is recommended by Florida LRFD Guidelines.

p -constant, / = 1.5 is recommended by Florida LRFD Guidelines.

* Prediction equations recommended by ACI 209









The prediction equations recommended by ACI for estimating the elastic modulus of

concrete are given as follows:

Ec = A (2-3)
Where

Ec -Elastic modulus (psi)

f -Compressive strength of concrete (psi)

A -constant, A = 57000 is recommended by ACI 318.

The following equation recommended by ACI 318-89 (revised 1992) for structural

calculation is applicable to normal weight concrete:


E = ac +/ (2-4)
Where

Ec -Elastic modulus (GPa)

f/ -Compressive strength of concrete (MPa)

a -constant, a = 3.32 is recommended by ACI 318.

p -constant, / = 6.9 is recommended by ACI 318.

The next equation given by ACI 363R-92 is applicable for predicting elastic modulus of

concretes with compressive strength up to 83 MPa (12000 psi)

Ec = 3.65 (2-5)
Where

Ec -Elastic modulus (GPa)

f -Compressive strength of concrete (MPa)

CEB-FIP Model (1990)









CEB-FIP Model (COMITE EURO-INTERNATIONAL DU BETON) Code (1990) also

offers the following model for prediction of time-dependent modulus of elasticity. The equation

is given as follows:


0.5 0.5
28
E (t)= exp s. 1 -E (2-6)


Where

s- A coefficient depending on the type of cement; s = 0.20 for rapid hardening high

strength cements, 0.25 for normal and rapid hardening cements, and 0.38 for slow hardening

cements.

t Age of concrete (days).

ti-1 day

Eci Modulus of elasticity of concrete at age of 28 days.

2.4 Shrinkage Behavior of Concrete

2.4.1 Origin of Shrinkage of Concrete

According to the mechanisms of concrete shrinkage, shrinkage of concrete consists of

plastic shrinkage, autogenous shrinkage (a process known as self-desiccation), drying shrinkage,

and carbonation shrinkage.

Autogenous shrinkage is the consequence of withdrawal of water from the capillary pores

by the anhydrous cement particles. Most of the autogenous shrinkage will take place at the early

age of hydration of cement. However, for concrete mixtures with a very low W/C ratio, this

procedure may last longer if moisture is available from ambient environment.

Plastic shrinkage and drying shrinkage are caused by withdrawal of water from concrete

under the condition of humidity gradient between the interior of concrete and air. Plastic









shrinkage may lead to the interconnection among capillary pores, the main factor contributing to

cracking of concrete at early age as well as increasing permeability of concrete.

Carbonation shrinkage is caused by carbonation of calcium hydroxide in the concrete.

Thus, carbonation shrinkage normally takes place on the surface of concrete elements. But, if

there are penetrated cracks in concrete, carbonation shrinkage may take place in the interior of

concrete. Carbonation of concrete will decrease the PH-value inside concrete so that

reinforcement can be easily corroded.

2.4.2 Significance of Studying Shrinkage of Concrete

Shrinkage of concrete, one of the main factors in determination of the endurance of

concrete structure, is a very important property of concrete to be evaluated. Excessive shrinkage

is blamed for leading concrete to crack, even fail. At the early age of concrete, low early strength

can not resist the stresses induced by drying shrinkage so that shrinkage-induced cracking can

subsequently lead to premature failure of the concrete structure. Cracks in concrete increase the

permeability of concrete and control the corrosion initiation time and corrosion rate of steel

reinforcement in the concrete structure. Shrinkage-induced cracks become a severe problem for

marine concrete structures or concrete structures close to the coastal region. The penetration of

aggressive ions through cracks into the interior of concrete is a very critical factor in causing the

corrosion of steel reinforcement. For prestressed concrete elements, not only does the shrinkage-

induced cracking speed up the corrosion of reinforcement, shrinkage deformation, which

accounts for up to 15% of total prestress loss, is also one of the main factors contributing to

prestress loss.

The shrinkage behavior of concrete is great affected by coarse aggregate content, coarse

aggregate type, cementitious material content and water content. For instance, an increase in

volume of aggregate in concrete will usually lead to a decrease in cement content, which would









lead to reduced shrinkage for the concrete. However, a reduction in cement content does not

necessarily cause a reduction in the strength of the concrete. Thus, through optimizing mix

proportion of concrete mixture, it is possible to design a concrete with low cement content and

low shrinkage without sacrifice of strength.

2.4.3 Effect of Raw Materials on Shrinkage of Concrete

2.4.3.1 Effect of aggregate content on shrinkage behavior of concrete

The contribution of coarse aggregate to decreased shrinkage of concrete is attributed to the

decrease of cement paste volume in the concrete mix. In 1956, Pichett [G.Pichett, 1956]

reported that the shrinkage ratio increases significantly as the aggregate content decreases. The

possible reason to explain the effects of coarse aggregate content on shrinkage strain of concrete

is shown in Figure 2-3. For the lean concrete mixture with a high coarse aggregate content, the

coarse aggregate particles will have point-to-point contacts or even face-to-face contacts with

each other. So a concrete with such a stiff aggregate skeleton will be very effective in resisting

stresses caused by cement paste shrinkage because aggregate particles cannot be pushed more

closely under the action of interior stress cause by shrinkage. Thus, shrinkage strain is

dramatically reduced. But, for rich concrete, the situation is otherwise.




CA
.. . . ............... ........................::::::








a. Lean concrete b. Rich concrete


Figure 2-3 Effect of coarse aggregate content on the shrinkage of concrete









Similarly, in 1960, Hermite [R.L'Hermite, 1960] carried out a study of the effects of

cement content on shrinkage behavior of concrete. The tests were performed at a curing

temperature of 68F, 50% relative humidity and wind velocity of 2.25 mph. The results indicated

that, at the early age of concrete, the shrinkage strain of the concrete with a cement content of

850 lb/yd3 (typical cement content for flowable concrete) is almost three times higher than that

of concrete mixtures with a cement content of 340 lb/yd3.

Leming [Leming, M. L, 1990] investigated the mechanical properties of high strength

concrete with different raw materials. These materials represent those used in structures built

under North Carolina Department of Transportation control. The data from shrinkage tests

showed that shrinkage strain of concrete varies significantly depending on the specific raw

materials used and the strength levels attained.

Research was carried out by Alfes [Alfes, 1992] on how shrinkage was affected by the

aggregate content, the aggregate modulus of elasticity, and the silica fume content. The

experiment was conducted using W/C ratio in the range of 0.25 to 0.3 with 20% silica fume by

weight of cement and varying amount and type of aggregates (basalt, LD-slag, and iron

granulate), and compressive strength of concretes at 28-day age were in the range of 102 to 182

MPa (14,600 to 26,000 psi). The test results showed that there is a direct and linear relationship

between the shrinkage value and the modulus of elasticity of the concrete.

In 1993, Zia et al. [Zia et al, 1993c, 1993d, 1993e] evaluated the shrinkage behavior of

VES, HES, VHS concretes with different aggregates (crushed granite, marine marl, rounded

gravel, and dense limestone). Shrinkage measurements were made for three to nine months in

different cases. The observed behavior followed the general trend of conventional concrete

except for the two cases of VES concrete using special blended cement (Pyrament) with marine









marl and rounded gravel as aggregates. In these two cases, the specimens exhibited an expansion

of approximately 140 microstrains, rather than shrinkage for the entire period of 90 days. The

expansion was attributed to the lack of evaporable water in the concrete because of its very low

W/C (0.17 for marine marl, and 0.22 for rounded gravel).

2.4.3.2 Effects of coarse aggregate type on concrete shrinkage

The skeleton of coarse aggregate in a concrete can restrain the shrinkage of the cement

matrix. The extend that the coarse aggregate skeleton can resist the stress caused by shrinkage-

induced stress from cement matrix depends on how stiff the coarse aggregate is. That is to say,

the elastic modulus of the aggregate determines the extent of restraining action to the shrinkage

of concrete. For example, the shrinkage of a concrete made with a steel aggregate will be lower

than the one made with a normal aggregate. Similarly, the shrinkage of a concrete made with

expanded shale aggregate will be higher than the one made with a normal aggregate.

The above hypothesis was verified by the many studies performed in the past decades. In

1958, Troxell, Raphael and Davis [Troxell et al, 1958] performed tests to study the effects of

coarse aggregate of different types on shrinkage behavior of concrete. The tests were carried out

on the concrete mixtures with a fixed mix proportion. The results showed that there is a

considerable variation in the shrinkage strain of the resulting concrete batched with coarse

aggregate of different types. They made a conclusion that this phenomenon is due very likely to

the difference in modulus of elasticity among aggregates of different types. Generally speaking,

the elastic property of aggregate determines the degree of restraint to the cement matrix.

Reichard [Reichard, 1964] agreed that the coarse aggregate has significant effect on

shrinkage behavior of concrete. A normal natural aggregate is usually not subject to shrinkage.

However, there exist rocks that can shrink up to the same magnitude as the shrinkage of concrete

made with non-shrinking aggregate.









2.4.3.3 Effects of size and shape of coarse aggregate on concrete shrinkage

Aggregate size and shape also affect the shrinkage of hardened concrete. The experimental

study conducted by Collins [Collins, 1989] on shrinkage of five high-strength concrete mixtures

with varied paste content, aggregate size showed that shrinkage deformations were somewhat

less for concrete mixtures with lower paste contents and larger aggregate size.

A study by Bisschop, Pel, and Van Mier [Bisschop et al, 2000] indicated that the total

length and the depth of micro-cracking caused by shrinkage of concrete will increase with larger

aggregate size. McQueen, Rapol, Flynn [Roy D. McQueen et al, 2002] performed laboratory

shrinkage tests in accordance with ASTM C 157 on a matrix of 16 concrete mixes to evaluate the

effects coarse aggregate size on shrinkage of concrete. The tests were conducted on mixes with

ASTM C 33, No.57 (38-mm maximum aggregate size) and No. 467 (64-mm maximum

aggregate size) coarse aggregates. The results of the laboratory shrinkage tests revealed that the

maximum size of the coarse aggregate (No.57 or 467) did not influence the shrinkage.

A study on evaluation of high performance concrete pavement carried out by Ozyildirim

[Ozyildirim, C, 2000] showed that concrete using smaller coarse aggregate commonly exhibits

greater shrinkage and increases potential for slab cracking because of increased paste

requirements. Larger maximum coarse aggregate sizes, on the other hand, require less paste, less

cementitious material, and less water, thereby resulting in reduced shrinkage; they also provide

increased mechanical interlock at joints and cracks.

Thus, there is still some controversy about how coarse aggregate size will affect the

shrinkage behavior of concrete. Test data from the specific concrete are necessary to control

concrete quality.









2.4.3.4 Effect of other factors on shrinkage behaviors of concrete

Shrinkage behavior of concrete is affected not only by coarse aggregate, but also by other

factors, such as water content, specimen size, ambient conditions, admixtures as well as mineral

additives.

Water content is the most important factor influencing shrinkage behavior of concrete.

Normally, the higher the W/C ratio is, the higher the shrinkage. This occurs due to two

interrelated effects. As W/C increases, paste strength and stiffness decrease; and as water content

increases, shrinkage potential increases.

The specimen size affects the diffusion rate of free water from the interior to exterior of

concrete. Thus, both the rate and the total magnitude of shrinkage decrease with an increase in

the volume of the concrete member because, for larger members, more time is needed for

shrinkage effects to reach the interior regions. For instance, the study by Hindy et al. [Hindy et

al, 1994] showed that dry shrinkage of small specimens measured by the conventional laboratory

test was found to over-estimate shrinkage of the concrete in the real structure.

Ambient conditions, such as relative humidity and temperature, greatly affect the

magnitude of shrinkage. They are blamed for affecting shrinkage behavior because they create

the relative humidity gradient and relative temperature gradient between the interior and exterior

of concrete, which is driving force to concrete shrinkage. The higher the relative humidity, the

lower the rate of shrinkage is. The lower the temperature gradient, the lower the shrinkage rate

is. Thus, the investigation conducted on shrinkage behavior of concrete has to simulate the real

environmental conditions in order not to overestimate shrinkage strain. For example, Aitcin et al.

[Aitcin et al, 1990] reported that the surface shrinkage strains under the field condition were

considerably lower than those measured under the laboratory conditions.









Mineral additive effect on shrinkage behavior varies according to the type of mineral

additive. Any material which substantially changes the pore structure of the paste will affect the

shrinkage characteristics of the concrete. In general, as pore refinement is enhanced, shrinkage is

increased. Pozzolans typically increase the drying shrinkage, due to several factors. With

adequate curing, pozzolans generally increase pore refinement. Use of a pozzolan results in an

increase in the relative paste volume due to the following two mechanisms: 1) In practice, slowly

reacting pozzolans (such as Class F fly ash) are frequently added to replace cement by weight

rather than by volume according to conventional concrete mix design method. This will increase

paste volume since pozzolans have a lower specific gravity than Portland cement. 2)

Additionally, since pozzolans such as fly ash and slag do not contribute significantly to early

strength, concrete containing pozzolans generally has a lower stiffness at earlier ages as well,

making them more susceptible to increased shrinkage under standard testing conditions.

2.4.4 Models to Predict Concrete Shrinkage

Misprediction of shrinkage usually does not cause structural collapse, but puts the structure

out of service, i.e. the structure does not live as long as the projected life span. The widespread

occurrence of such lack of long-term serviceability inflicts a tremendous economic damage on

many nations. The direct signs of damage that put a structure out of service are typically cracks,

which may cause major fractures.

Even though the mechanisms of shrinkage, such as micromechanics mechanism and

diffusion mechanism, have been studied extensively, their correlations with macroscopic

behaviors have been intuitive and non-quantitative. As pointed out by Bazant and Carol [Bazant

et al, 1993], such studies generally have not borne much fruit. Since the uncertainty in the

prediction of shrinkage behavior with the variations of concrete compositions and random

environmental conditions is enormous, the models established at present relies on purely









empirical relations without micromechanics models involved. In addition, substantial effort has

been paid in stochastic phenomena and probabilistic models, but similar to the preceding topic,

nothing is being introduced into practice.

At present, the empirical formula given by the ACI Committee 209 [1993] is widely used

to predict shrinkage strain. But, it should be noted that ACI 209 equation could well be in error

unless broad corrections are applied, for instance, to correct for curing and size effect, and to

account for humidity and composition effects. As pointed out by Hindy et al. [Hindy et al, 1994],

the ACI 209 predictive equation was found to be valid for the high performance concretes only if

new values for the parameters were introduced.

Thus, owing to many uncertainties in current models, it is very necessary to perform tests

on the specific concrete mixtures designed using local available materials to guarantee the safety

of structures. Then, based on the accumulated data, constitutive parameters characterizing the

shrinkage behaviors of concretes designed based on local available materials can be obtained.

In the following sections, the shrinkage prediction models offered by CEB-FIP model code

(1990) and ACI-209 (1992) are reviewed briefly.

2.4.4.1 CEB-FIP Model for shrinkage strain prediction

In this model, the effects of cement type, ambient relative humidity, compressive strength

of concrete, and size effect of specimen on shrinkage strain of concrete are taken into

consideration. The total shrinkage strain may be estimated by the following equation:

E [t, t =_ -E t t- t (2-7)
cs s csO s s)
Where

E, (t, t,) -Time dependent total shrinkage strain

E ,o -Notational shrinkage coefficient









/8, (t ts)-Coefficient to describe the development of shrinkage with time

Eco can be estimated by the following equation:


E == 160+10sc 9- cm x10-6 .-RH (2-8)
csO sc f RH

Where sc, -A coefficient which depends on the type of cement: sL, = 4 for slowly

hardening cements; 5 for normal or rapid hardening cements; 8 for rapid hardening high

strength cements.

fc, -The mean compressive strength of concrete at the age of 28 days.

fcmo=1 MPa

/RH = -1.55,sRH for 40% < RH < 99% ;

/RH = 0.25 for RH > 99%

Where


Ps = 1-r (2-9)
sRH RH
RH The relative humidity of the ambient environment (%).

RH0 -100%

s, (t ts) can be estimated by the following equation:

0.5
(t ts)

s t ts )= -tl2 (2-10)

350. +
hWh te
Where








2A
h = 2A The notational size of member (in mm), where A, is the cross-sectional area
u

(mm2) and u is the perimeter (mm) of the member in contact with the atmosphere.

ho-100 mm

ti -1 day

2.4.4.2 Prediction model recommended by ACI-209 Report [1992]

The concrete shrinkage prediction model recommended by ACI-209 (1992) is shown by

the following equation:

S) t (2-11)
( sh )t 35 +t ( sh )u (2-11)
Where

(Esh ) Time dependent shrinkage strain

(sh )u Ultimate shrinkage strain

t Time in days

If there is no available shrinkage data from the concrete to be evaluated, the ultimate

shrinkage strain, (Esh ) can be assumed to be the following:

sh) = 780 x10-6 xh (2-12)
where

Ysh a product of all the applicable correction factors for the testing conditions other than

the standard condition; Ysh = 1 under standard testing condition.

Ysh is obtained by multiplying the ultimate shrinkage strain under the standard condition by

the appropriate correction factors as described in the following:

Correction factors for the effect of initial moist curing. The correction factor is equal to 1.0
for concrete cylinders moist-cured for 7 days, and 0.93 for that moist-cured for 14 days.









* Correction factor for the effect of ambient relative humidity. The following formulas are
given for use in obtaining the correction factor for shrinkage test performed under the
condition of ambient relative humidity greater than 40%.

=1.40 0.0102A, for 40 < A < 80 (2-13)
y, =3.00 0.030A, for 80 < A < 100 (2-14)
where
y, Correction factor for the effect of relative humidity
k Relative humidity

* Correction factor for the effects of specimen size. The correction factor in consideration of
the specimen size effect (y,) is given by the following equation:


yV =1.2exp(-0.12 -) (2-15)
s
where
ys Correction factor for the effects of specimen size
v
-- Volume-surface area ratio of the specimen in inches
s

* Correction factor for concrete composition. Various equations for calculating the
correction factors for the effects of the slump of the fresh concrete, aggregate content,
cement content and air content of the concrete have also been given in this model.

2.5 Creep of Concrete

2.5.1 Rheology of Materials and Definition of Creep of Concrete

The philosophical origin of rheology is owed to Heraclitus. As exemplified in his famous

aphorism "Panta Rhei" ("Panta Rei"): Everything flows and nothing stands still.

Inspired by this expression, rheology, the term was coined by Eugene Bingham, a

professor at Lehigh University, in 1920, and was defined as the study of the deformation and

flow of matter under the influence of an applied stress. One of the tasks of rheology is to

empirically establish the relationships between deformations and stresses by adequate

measurements. Such relationships are then amenable to mathematical treatment by the

established methods of continuum mechanics.










The theological phenomenon of concrete materials, also termed as creep, is one of very

important theological properties of concrete. Since creep behavior of concrete is characterized by

time-dependence, it generates substantial effects on the structural stability during its service life.

Thus, it is of great importance to know the creep behavior of specific concrete before it can be

used for structure design.


Ct
Ct


I I Tertiary creep

Steady-state creep
Transient creep


Time

Figure 2-4 Creep diagram of concrete material

Creep of concrete can be defined as the time-dependent deformation of concrete materials

under a sustained stress. As shown in Figure 2-4, load-induced creep consists of three stages,

namely primary or transient creep stage, steady-state creep or secondary creep stage and tertiary

creep stage. The primary or transient creep is characterized by a monotonic decrease in the rate

of creep. The feature of secondary or steady-state creep is that material will show constant creep

rate. At last, in tertiary creep stage, creep rate will increase till material fails.

Figure 2-5 shows a plot of strain versus time for a concrete that was loaded for some time

and then unloaded. The permanent strain that remains after the load has been released is called

the creep strain. For concrete materials, creep strain consists of two main components. The first

component is the true or basic creep, which occurs under the conditions of no moisture

movement to or from the ambient medium. This is the case for concrete element functioning as









underground foundation, or inside water. The second component is the drying creep, which

takes place while concrete is subjected in ambient conditions. Normally, the creep strain that is

considered in structural design is the sum of basic creep strain and drying creep strain.

Due to the difficulty to differentiate delayed elastic strain from creep strain and the

convenience to build a numerical model to simulate time-creep strain curve with the delayed

elastic deformation included, the total creep strain would usually include both the delayed elastic

deformation and permanent creep deformation. Also, the above mentioned approach is usually

taken since the delayed elastic strain is usually very small compared with the total creep strain.

The creep behavior of concrete materials plays a great role in the stability of concrete

structures. Also, the creep behavior of concrete is subjected to the severe volatility caused by the

variation of raw materials for concrete mixtures and their proportions. Therefore, over the past

decades, the study on creep of concrete has been one of engineers' focuses.





Instantaneous recovery


Delayed elas ic recovery



Elastic strain Perman t creep

Time since application of load


Figure 2-5 Strain-time plot of concrete under a sustained load and after release of load

2.5.2 Significance of Studying Creep Behavior of Concrete

Creep in concrete can have both positive as well as negative effects on the performance of

concrete structures. On the positive side, creep can relieve stress concentrations induced by









shrinkage, temperature changes, or the movement of supports. For example, in indeterminate

beam with two fixed ends, creep deformation will be very helpful in reducing tensile stress

caused by shrinkage and temperature variation.

On the other hand, in some concrete structures, creep can do harm to the safety of the

structures. For instance, creep deformation can lead to an excessive deflection of structural

members, creep buckling or other serviceability problems especially in high-rise building,

eccentrically loaded columns and long bridges. In mass concrete, creep may be a cause of

cracking when a restrained concrete mass undergoes a cycle of temperature change due to the

development of heat of hydration and subsequent cooling. For prestressed concrete structures,

such as composite bridges, pre-stressed shells, or continuous girders, the desirable creep of

concrete would be as low as possible. Heavily pre-stressed members and long members are

particularly susceptible to large volume changes. If a pre-stressed member is restrained in

position prior to the majority of the volume change has taken place, the pre-stressed members

will exert excessive forces on its connections and supporting structures that could cause a

structural failure. Also, another very important issue caused by creep deformation is prestress

loss, accounting for more than 25% of total prestress loss.

2.5.3 Effect of Aggregate on Creep of Hardened Concrete

Aggregates play an important role in creep of concrete. Coarse aggregate reduces creep

deformation by reducing the cement paste content and restraining the cement paste against

contraction. Generally, concretes made with an aggregate that is hard and dense and have low

absorption and high modulus of elasticity are desirable when low creep strain is needed.

The study by Troxell, Raphael, and Davis [Troxell et al, 1958] indicated that the creep

strains of the concrete mixtures with different types of aggregate will behave differently. The









highest creep value is obtained from the concrete made with sandstone aggregate, and the lowest

creep value is obtained from the concrete made with limestone.

Rusch et al [Rusch, 1963] found an even greater difference between the creep strains of

concretes made with different aggregates. After 18 months under the load at a relative humidity

of 65%, the maximum creep strain of the concrete made with sandstone was five times higher

than the minimum creep strain of the concrete made with basalt.

Alexander, Bruere and Ivanusec studied the influence of 23 aggregate types on creep

deformation of concrete [Alexander et al, 1980]. Creep tests were conducted in a controlled

environment at 23 C and 60 % relative humidity. Creep tests were conducted for six months

after a 28-day water cured period in lime-saturated water to allow for minimal effects of

hydration. Strains were measured using longitudinal gages on two opposite faces of the prism

with a gage length of 100 mm (4 in). The conclusion shows that aggregates with a lower

absorption will produce concrete with a lower creep deformation. It was further determined that

the aggregate with a high elastic modulus will produce low creep values.

Collins [Collins, 1989] examined the creep property of high strength concrete. Creep tests

were conducted according to ASTM C 512. The results demonstrated that a concrete with a

larger aggregate size and lower paste content would provide a lower creep strain.

Creep tests done by Hua [Hua, 1995] on pure hardened cement pastes and on a reference

concrete (made with the same paste) also show that creep is reduced by the presence of

aggregate.

In addition, the conclusion on the effect of coarse aggregate content on creep of concrete is

also confirmed by the tests on lightweight aggregate concrete. The study by Gesoglu, Ozturan









and Guneyisi [GesoAlu et al, 2004] showed that concretes containing higher lightweight coarse

aggregate content had a lower creep strain at all W/C.

2.5.4 Prediction Models and Their Limitations of Concrete Creep

With the exception of creep buckling, overestimation or underestimation of creep usually

does not lead to structural collapse, but merely shortens the structural service life. But,

misprediction of creep could put tremendous economic loss.

Thus, accurate prediction of the ultimate creep strain of concrete is of great importance. In

order to obtain an accurate prediction, the following mechanisms possibly resulting in creep of

concrete have been studied, including micromechanics mechanism, diffusion phenomenon,

thermodynamics mechanism, and other mechanism coupled with damage and fracture.

Micromechanics mechanism in creep behavior has been studied extensively through the

study of the microstructure of cement and concrete for decades. However, the macroscopic

constitutive relations based on the intuitively and non-quantitatively observed phenomenon or

postulated on the microstructure or even molecular level generally are not promising. The

uncertainty in the prediction of long-term creep associated with the variations of concrete

composition is enormous, actually much larger than any uncertainty except that due to the

randomness of environment. Thus, even though the attempts at the mathematical

micromechanical modeling of some phenomena have already begun, there is sill quite a distance

to make them practical.

Diffusion phenomenon can be considered another very important mechanism for creep

behavior of concrete because creep of concrete is always associated with the moisture and heat

transport between the interior concrete and outside environment. Therefore, in concrete

structures exposed to the environment or subjected to variable temperatures, there is no hope of

obtaining realistic stresses without actually solving the associated problems of moisture and heat









transport, at least in an approximate manner. It has been shown that creep and shrinkage analysis

based on diffusion analysis of a box girder bridge segment yields enormous stresses which are

routinely neglected in practice.

The models based on statistics have been studied extensively. Although the statistical

variability of concrete creep under controlled laboratory conditions is quite small, very large

statistical fluctuations are caused by the environment as well as the uncertainties in the effect of

concrete composition. In most practical situations, sophisticated deterministic mathematical

analysis makes in fact little sense, because the uncertainties of stochastic origin are much larger

than the errors of simple effective modulus solutions compared with sophisticated deterministic

analytical solutions of differential or integral equations.

Due to complex influences coming from raw materials and ambient environment, the

common problem with the current models is that they are only feasible to be used for the creep

prediction of similar concretes, which means concretes from the same geographical region. The

concretes used in the Florida region are generally quite similar and, instead of repeating

measurements for each new major structure, one can greatly improve predictions on the basis of

previously obtained data for a similar concrete from the same region. Equally important will be

application of the existing fundamental research results in practice. Since each of these models is

applicable under specific conditions for a certain class of materials, the proper utilization of these

models depends essentially on the practical experience of the researcher. The accumulation of

this experience is the purpose of most experimental works on creep. This is due mainly to the

fact that 1) more than one microscope mechanism are involved in inducing creep of concrete,

and 2) some empirical models only can be used for certain types of concretes without the

variation of concrete components, proportions and applied environmental conditions. If the









empirical model obtained from the concretes used in a given region is applied to predict creep

strain of the concretes in another region, the results could be very scary.

Over the years, many equations have been developed for the description of steady-state and

transient creep. But, most of them are either too complicated theoretically to bring them into

practical use, or have an empirical character and were determined on the basis of a fit to the

experiments, which cause great uncertainties in the extrapolation to long time intervals and to

conditions not covered in the laboratory.

In the following sections, two creep prediction models, namely CEB-FIP model and ACI

209 model will be reviewed.

2.5.4.1 C.E.B-F.I.P Model Code

In this model, the creep strain can be predicted by the following equation:

c (to)
Ecr (t, t) = 0 28(t t0) (2-16)
cl
Where

cr (t, t,) Creep strain at time t

ca (to) -Applied stress

2, (t, to) Creep coefficient

Ec Modulus of elasticity at the age of 28 days

The modulus of elasticity can be estimated by the following equation:


4 f k+Af
E =ca *10 c4.( C3
cW E rfe
cmo
Where


(2-17)









fck Characteristic strength of concrete (in MPa); Af = 8MPa; fm = 10MPa;

aE = 2.15x 104MPa

The creep coefficient 28(t, t) can be calculated as follows:


28 (t, tO) = O 8c (t- tO)
Where

-0 -Notational creep coefficient.

p Coefficient to describe the development of creep with time after loading

t Age of concrete in days

to Age of concrete when loaded in days

The notational creep coefficient can be estimated as follows:

0 = RH- "(fcm) f(to)
1-RH/RH0
ORH= + 10/
0.46. (hI/h)ll3
5.3
fl(fc) !=~fcm fcmo


O.l+(to0 /tl02

Where

fc, = fck+ Af ,

h Notational size of the member (in mm)= 2A /u .

Ac Cross-sectional area (in mm2)

u Perimeter of the member in contact with the atmosphere (in mm)

ho 100 mm.

RH Relative humidity of the ambient environment (in %).


(2-18)


















(2-19)









RHO 100%

t, 1 day.


(tt -t)/t1
p8(t to) = +(- t-t










(t- to)06


(2-20)


28(tt ) (to). 0.6 (2-21)
10 + (t t0
Where

28 (t, to) Creep coefficient at time t

& (to) Ultimate creep coefficient

to Time of loading

The ultimate creep coefficient can be expressed as:

oo (t0) = c"o (2-22)
The constant & = 2.35 is recommended. The correction factors yT consist of the following

terms:

Yc = la YRH Yat *s *Yp Ya (2-23)
Where









y)a Correction factor for loading age. For loading ages later than 7 days and moist cured

concrete, yo = 1.25 (to) 0118 For loading ages later than 1-3 days and steam cured

concrete, yo = 1.13 (t 0)Y 094


YRH Correction factor ambient relative humidity. For ambient relative humidity greater

than 40%, y, = 1.27 0.0067 RH (RH is the ambient relative humidity in %)

y, Correction factor for slump of fresh concrete. y, = 0.82 + 0.00264 S, (S, in mm)

Yp Correction factor for fine to total aggregate ratio. y/ = 0.88 + 0.0024 pa (P is fine

to total aggregate ratio)

ya Correction factor for air content. yT = 0.46 + 0.09 aa (aa is air content)

Yt, Correction factor for thickness of member. When the average thickness or volume to

surface ratio of a structural member differs from 150 mm or 38 mm, respectively, two

methods are offered for estimating the factor of member size y,:

S Average-thickness method

For an average thickness of a member smaller than 150 mm, the factors are given by ACI-
209 Report. For an average thickness of a member larger than 150 mm and up to about 300
to 380 mm, the correction factor for thickness is given as:

Ya, = 1.14 0.00092 ha During the first year after loading

ya, = 1.10 0.00067 h For ultimate values

Where

ha = Average thickness of a member in mm.

S Volume-surface ratio method

2 -013 213 (2-24)
2T -I +1.13 e (2-24)
3










Where

v

s = Volume to surface ratio in mm.









CHAPTER 3
MATERIALS AND EXPERIMENTAL PROGRAMS

3.1 Introduction

This chapter describes the mix proportions and ingredients of typical concrete mixtures

used in this research, the method of preparation of the concrete mixtures, fabrication procedure

of the test specimens and routine ASTM testing methods and procedures used in this study.

3.2 Concrete Mixtures Evaluated

3.2.1 Mix Proportion of Concrete

The concrete mixtures were randomly selected from typical Class II, IV, V and VI

concretes made with normal-weight and lightweight aggregates. They are representative concrete

mixes broadly used in Florida. The range of designed compressive strength of concretes varied

from 4,000 to 11,000 psi at the age of 28 days. Class F fly ash and ground blast-furnace slag

were used as additives in these mixes. Water reducing and air entraining admixtures were used

throughout all the mixtures.

Water to cementitious materials ratio for all the mixtures was determined according to the

design strength of specified concrete. Workability of fresh concrete in terms of slump value, was

controlled by the dosage of water reducer, super plasticizer and air entraining agents. Since

strength of concrete is very sensitive to the variation of air content and water content, to meet

target slump value, the dosage of water reducer and superplasticizer were adjusted rather than the

dosage of air entraining agent and water. In addition, another reason to add air entraining agent

to concrete is to improve durability of concrete.

A total of 14 different concrete mixtures were evaluated. The detailed mix proportions for

the fourteen mixtures are presented in Table 3-1. Miami Oolite limestone was used as a coarse

aggregate for Mix-iF, 2F, 3F, 4F, 5S, 6S, 7S, and 8S. Stalite lightweight aggregate was used for









Mix-9LF and Mix-O1LS. Mix-2GF, Mix-3GF, Mix-5GS and Mix-7GS had identical mix

proportion to the Mix-2F, Mix-3F, Mix-5S and Mix-7S with the exception that the coarse

aggregate was replaced by a granite aggregate by volume. Fly ash was used in Mixes 1F, 2F, 3F,

4F, 9LF, 2GF and 3GF, and slag was used in Mixes 5S, 6S, 7S, 8S, 10LS, 5GS and 7GS. Mixes

1F, 2F, 3F, 4F, 5S, 6S, 7S, 8S, 9LF and 10LS were replicated.

3.2.2 Mix Ingredients

The mix ingredients used in producing the concrete mixtures are described as follows:

* Water

Potable water was used as mixing water for production of the concrete mixtures. The water
temperature was around 64F.

* Cement

Type-I Portland cement from CEMEX Company was used. The physical and chemical
properties of the cement as provided by Florida State Materials Office are shown in Table
3-2 and Table 3-3.

* Fly ash

The fly ash used in this study was provided by Boral Company. Its physical and chemical
properties as provided by Florida State Materials Office are presented in Table 3-4.

* Slag

The slag used in this study was provided by Lafarge Company. Its physical and chemical
properties as provided by Florida State Materials Office are shown in Table 3-5.

* Fine aggregate

The fine aggregate used was silica sand from Goldhead of Florida. The physical properties
of the fine aggregate as determined by Florida State Materials Office are shown in Table 3-
6. The gradation of the fine aggregate is shown in Figure 3-1. The fine aggregate was
oven-dried before it was mixed with the other mix ingredients in the production of the
concrete mixtures.

* Air-entraining admixture

The air-entraining admixture used was Darex AEA from W.R. Grace & Co. Darex AEA is
a liquid admixture for use as an air-entraining agent, providing freeze thaw durability. It
contains a catalyst for more rapid and complete hydration of Portland cement. As it imparts









workability into the mix, Darex AEA is particularly effective with slag, lightweight, or
manufactured aggregates which tend to produce harsh concrete.

* Coarse aggregates

Three different types of coarse aggregates were used in this study. The first one is a normal
weight Miami Oolite limestone. The second one is Georgia granite aggregate. The third
one is called 'Stalite', a lightweight aggregate from South Carolina. The physical
properties of these three coarse aggregates are displayed in Table 3-7. The gradation of the
Miami Oolite is shown in Figure 3-2; the gradation of the Georgia granite aggregate is
plotted in Figure 3-3; and the gradation of Stalite aggregate is presented in Figure 3-4. In
order to have a good control on the moisture content of coarse aggregates, the coarse
aggregates were soaked in water for at least 48 hours and then drained off the free water on
the surface of aggregate before they were mixed with the other mix ingredients in the
production of the concrete mixtures.

* Water-reducing admixture

The water-reducing admixture used included WRDA60, WRDA64, and ADVA120 from
W.R.Grace & Co. WRDA 60 is a polymer based aqueous solution of complex organic
compounds producing a concrete with lower water content (typically 8-10% reduction),
improved workability and higher strengths. It can be used in ready mix, job site and
concrete paver plants for normal and lightweight concrete. It also can be used in block,
precast and prestress work. In addition, it offers significant advantages over single
component water reducers and performs especially well in warm and hot weather climates
to maintain slump and workability in high ambient temperatures. WRDA 64 is a polymer
based aqueous solution of complex organic compounds producing a concrete with lower
water content (typically 8-10% reduction), greater plasticity and higher strength. Except
significant advantages like WRDA 60, WRDA 64 performs especially well in concrete
containing fly ash and other pozzolans. ADVA 120, a superplasticizer, is a polymer based
liquid organic compounds increasing plasticity of concrete.


3.3 Fabrication of Concrete Specimens

3.3.1 The Procedure to Mix Concrete

The concrete mixtures investigated in this study were produced in the laboratory using a

compulsive pan mixer with capacity of 17 cubic feet, as shown in Figure 3-5. For each mixture,

thirteen (13) cubic feet of fresh concrete was produced to fabricate sixty (60) 6"x 12" cylindrical

specimens.












Table 3-1 Mix proportions of the 14 concrete mixtures used in this study

Coarse Agg. No. of Mix W/C Cement (lbs/yd3) Fly ash (lbs/yd3) Slag
(lbs/yd3)


Mix-1F* 0.24 800


Mix-2F*

Mix-3F*

Mix-4F*


0.33 656

0.41 494

0.37 600


---

---

---


400

380

461
306
---

423
---
---

400
461


Mix-5S* 0.33 400


Mix-6S* 0.36

Mix-7S* 0.41
Mix-8S* 0.44
Mix-9LF* 0.31
Stalite lightweight M 9L*
Mix-10LS* 0.39

Mix-2GF 0.33
Mix-3GF 0.41
Georgia Granite 41
Mix-5GS 0.33
Mix-7GS 0.41
Note: AE-air entraining admixture;


197 ---
306 ---

602 150

282 ---

656 144
494 123
400 ---
197 ---
* Mixtures were replicated.


Water FA CA
3? 3. 3 ? ?


Admixture


I


Miami Oolite


(OIs/yed) (lbs/yr) (lbs/ydr) AE WRDA/ADVA
(WRDA60)-300Z
236.0 931 1679 7.5 OZ (WRDA60)-300Z
(ADVA120)-600Z

265.6 905 1740 12.0 OZ (WRDA6
-30OZ
254.0 1175 1747 0.5 OZ (WRDA60)-33.40Z

278.0 1000 1774 2.0 OZ (WRDA60)
-560Z
(WRDA60)-240Z
262.0 1062 1750 6.0 OZ (WDA60)-240Z
(ADVA120)-480Z
270.0 1049 1736 1.9 OZ (ADVA120)
-380Z
267.0 1121 1750 4.6 OZ (WRDA60)-32.90Z
269.0 1206 1710 3.1 OZ (WRDA60)-30.60Z
235.3 952 1239 9.6 OZ (WRDA64)
-300Z
275.0 853 1300 8.8 OZ (WRDA64)-31.70Z

265.6 909 1981 12.0 OZ (WRDA60)
-300Z
254.0 1176 2027 0.5 OZ (WRDA60)-33.40Z
262.0 1066 2045 6.0 OZ (WRDA60)-240Z
267.0 1125 2045 4.6 OZ (WRDA60)-482.90Z
267.0 1125 2045 4.6 OZ (WRDA60)-32.90Z


I









Table 3-2 Physical properties of Type I cement
Loss on Ignition Insoluble Setting Time Fineness Compressive Strength Compressive Strength
(%) Residue (%) (min) (m2/kg) at 3 days (psi) at days (psi)
1.5% 0.48% 125/205 402.00 2400 psi 2930 psi


Table 3-3 Chemical ingredients of Type I cement
Ingredients Si02 A1203 CaO SO3 Na20-K20 MgO Fe203 C3A C3S C2S C4AF+C2F
(%) 20.3% 4.8% 63.9% 3.1% 0.51% 2.0% 3.3% 7% 59% 13.8% 15.8%

Table 3-4 Physical and chemical properties of fly ash
SO3 Oxide of Si, Fe, Fineness (%) Strength(7d) Strength (28d) Loss on Ignition % of Water
(%) Al (%) (ASTM C430) (ASTM C109) (ASTM C109) (%) (%) (ASTM C311) (ASTM C-618)
0.3 84 32 N/A 78 4.3 102


Table 3-5 Physical and chemical properties of slag
SO3 Oxide of Si, Fineness (%) Strength (7d) (%) Strength (28d) Loss on Ignition % of water
(%) Fe, Al (ASTM C430) (ASTM C109) (ASTM C109) (%) (%) (ASTM C311) (ASTM C-618)
1.7% N/A 4 92% 129 N/A N/A


Table 3-6 Physical properties of fine aggregate
Fineness Modulus SSD Specific Gravity Apparent Specific Gravity Bulk Specific Gravity Absorption
2.30 2.644 2.664 2.631 0.5%


Table 3-7 Physical properties of coarse aggregates
Aggregate SSD Specific Gravity Apparent Specific Gravity Bulk Specific Gravity Absorption


Miami Oolite
Stalite
Georgia Granite


2.431
1.55
2.82


2.541 2.360


2.85


2.80


3.03%
6.60%
0.58%











100 -

90 9

80

70o



w \
60



40 -



20

10 ------------
0

#4 #8 #16 #30 #50 #100 #200
Size of Sieve


Figure 3-1 Gradation of fine aggregate (Godenhead sand)


100

90 -

8 0 -----_--------------------
80

S 70

60

.I1 50------^----------
0
c50

a 5 40

c 30 -
I.. 20 ---------

20

10

0
1.5" 1" 0.5" 4# 8# 200#
Size of Sieve


Figure 3-2 Gradation of coarse aggregate (Miami Oolite limestone)
































1.5" 1" 0.5" 4# 8# 200#
Size of Sieve


Figure 3-3 Gradation of coarse aggregate (Georgia granite)


1.5" 1" 0.5" 4# 8# 200#
Size of Sieve


Figure 3-4 Gradation of lightweight aggregate (Stalite)



























Figure 3-5 Compulsive Pan Mixer

The procedures to fabricate cylindrical specimens were given as follows:

* According to mix proportion design, measure out the coarse aggregate, fine aggregate,
cement, mineral admixtures, water, high range water reducer, air entraining agent.

* Place coarse aggregate and fine aggregate into the pan mixer to mix for about 30 seconds.

* Place two thirds of the water together with the air-entraining admixture into the mixer and
mix for 1 minute.

* Place cement, mineral additives, such as slag or fly ash, as well as certain amount of high-
range water reducer into the pan mixer and mix for 3 minutes, followed by a 2-minute rest,
then, followed by a 3- minute mixing.

* Perform a slump test (according to ASTM C143) to determine whether or not the target
slump has been reached.

* If the target slump is not satisfied, add some more water-reducing admixture instead of
water to adjust slump of fresh concrete. In doing so, we can assure the design strength of
concrete will not be affected by adding extra water into concrete, which will change the
water to cementitious material ratio.

* Re-mix the fresh concrete for two more minutes. Then, perform another slump test to
check if the target slump has been reached. Repeat this procedure until the target slump is
achieved.









3.3.2 The Procedure to Fabricate Specimens

After the mixing procedure is completed, place the fresh concrete into 6"x 12" plastic

cylinder molds. Then two different procedures will be taken to consolidate the fresh concrete

inside plastic cylinder molds.

The first one is that, if the slump of the fresh concrete is less than 7 inches, fill each

cylinder mold to one third of its height, and place the mold on a vibrating table for 45 seconds.

Then fill the mold to another one third of its height, and place the mold on the vibrating table for

45 seconds. Then fill the mold fully, and place the mold on the vibrating table for 45 seconds. In

addition, for the mixtures without any slump value, the vibrating time to consolidate concrete

should be increased, or the vibrating intensity should be adjusted.

The second one is that, if the slump is more than 7 inches, fill each cylinder mold in three

layers, and rod each layers manually 25 times, as specified in ASTM C31.

In doing so, we can assure that the mixtures with low slump value can be well-compacted,

while the mixtures with very high slump value will not be segregated due to over-consolidation.

After consolidation, finish the surface of each concrete specimen with a trowel, and cover

the top of the cylinder with a plastic lid to keep moisture from evaporating. Then, allow the

concrete to be cured in the cylinder molds for 24 hours before demolding. But, for concretes

with very low compressive strength after 24 hours, allow another 24 hours of curing in the mold

before demolding.

At last, set the demolded concrete specimens in the standard moist curing room for the

specified curing time until testing.

3.4 Curing Conditions for Concrete Specimens

The concrete specimens for compressive strength test, split tensile strength test, and elastic

modulus test were cured in standard moist room until the age to be tested. Two different curing

66









conditions were applied to the concrete specimens of Mix-IF to Mix-O1LS for shrinkage and

creep tests. The first condition is to cure the concrete specimens for 7 days in the moist room and

followed by room condition for another 7 days. The second one is to cure the concrete

specimens for 14 days in the moist room and followed by room condition for another 14 days.

But, only one curing condition was applied to Mix-2GF, Mix-3GF, Mix-5GS and Mix-7GS,

i.e.14 days in moisture room, and then in room condition for another 14 days.

3.5 Tests on Fresh Concrete

In order to obtain concrete mixtures with uniform quality, ASTM standard tests, as shown

in Table 3-8, on fresh concrete were performed and described in detail as follows:

Table 3-8 The testing programs on fresh concrete
Test Slump Air Content Unit Weight Setting Time Temperature
ASTM ASTM ASTM ASTM ASTM
Test Standard
C143 C 173 C138 C403/C 403M C 1064

* Slump test

Slump test was performed in accordance with ASTM C143 standard. The slump value was
used to evaluate the consistency of fresh concrete.

* Air content test

Air content test was carried out in accordance with ASTM C 173 standard. The volumetric
method was employed for this test.

* Unit weight test

The procedures of ASTM C138 standard was followed in running the unit weight test.
This test was carried out to verify the density of concrete mixtures for quality control.

* Setting time test

ASTM C403/C 403M standard was followed to perform the setting time test. The mortar
specimen for the setting time test was obtained by wet-sieving the selected portion of fresh
concrete through a 4.75mm sieve. The proctor penetration probe was employed for
running this test. In this test, the initial setting time is determined when the penetration
resistance equals 500 psi, and the final setting time is determined when the penetration
resistance reaches 4000 psi.











* Temperature test

Temperature of the fresh concrete was determined in accordance with ASTM C 1064
standard. This test was used to ensure that the temperature of the fresh concrete was
within the normal range, and that there was no unexpected condition in the fresh concrete.
A digital thermometer was used to monitor the temperature of concrete.

The properties of the fresh concrete for each of the ten mixtures are presented in Table 3-9.

As can be seen from Table 3-9, the slump values of all the concrete mixtures fell in the range of

target slump value other than Mix-2F. The replicated Mix-2F had a slump value higher than the

target value. Also, the air contents of all the concretes were in the range of designed target value

other than Mix-2F and Mix-5S, which had air content slightly higher than the maximum target

value.

Table 3-9 Properties of fresh concrete


Mix-7GS 2.25


Target
slump


1.5-4.5


Air Target
Air Air
Content C ent
Content
(o) (%)

1.50
5 1.0-5.0
/1.25"
7.30
2.4-5.6
/4.50*
1.60
1.0-6.0
/2.50*
1.30
0.0-4.0
/2.00*
6.80
80 1.0-5.0
/3.75*
3.40
1.0-5.0
/2.25*
5.50

5.30
1.0-6.0
/3.75*
5.20
3.0-6.0
/3.00*
5.50
55 1.0-6.0
/5.25*
7.40 2.4-5.6
1.50 1.0-6.0
5.50 1.0-5.0
3.80 1.0-6.0


Unit
Weight
(lbs/yd3)

143.1
/145.5*
133.4
/137.7*
145.7
/143.9*
142.6
/143.8*
136.9
/141.6*
143.4
/141.4*
138.8
/138.0*
138.9
/140.4*
116.9
/117.78
111.6
/109.3*
144.9
150.1
145.8
147.3


Setting Time


Initial

7h0min

2h 50min

4h 55min






3h 10min






5h 35min

7h 45min


Final

8h 50min

4h 35min

7h 15min






4h 55min






7h 20min

10h Omin


Mixture
Temperature
(F)

80/81*

79/73*

79/76*

74/74*

81/78*

79/81*

77/79*

80/76*

79/80*

77/78*

78
79
76
74


* From first phase study


Mix
Number


Mix-IF

Mix-2F

Mix-3F

Mix-4F

Mix-5S

Mix-6S

Mix-7S

Mix8S

Mix-9LF

Mix-O1LS

Mix-2GF
Mix-3 GF
Mix-5GS


Slump
(in)

7.75
/9.75*
7.50
/4.25*
1.50
/2.00*
3.00
/3.00*
7.25
/9.00*
3.50
/5.50*
4.00
/5.75*
2.75
/3.00*
3.75
/2.50*
3.50
/2.75*
4.50
2.50
6.50









3.6 Tests on Hardened Concrete

Routine ASTM standard tests on the hardened concrete specimens are given in Table 3-10.

Table 3-10 The testing program on hardened concrete
Compressive Splitting Tensile Elastic
Test Shnnkage Creep
Strength Strength Modulus Shrinkage Creep
Test ASTM ASTM ASTM Described in Described in
Standard C 39 C 496 C 469 this chapter this chapter

3.6.1 Compressive Strength Test

Compressive strength test were performed on all the concrete mixtures investigated in this

study. Through the compressive strength test, the strength development characteristics of the

concretes typically used in Florida can be obtained. Furthermore, the results from compressive

strength tests can be used to calibrate the prediction equation given by ACI 209R Code so that a

reliable prediction equation can be obtained.

The test procedure of ASTM C 39 standard was followed for compressive strength test.

For each concrete mixture, three replicate 6"x 12" cylindrical specimens were tested for their

compressive strength at the age of 3, 7, 14, 28, 56, and 91 days, with a total of 18 specimens

tested. Before testing, both ends of concrete cylinders were ground in order to support the load

uniformly. The loading rate was controlled at 1000 lbf per second. Two typical failure modes in

the compression test are (1) column failure, and (2) shear failure. These two failure modes are

shown in Figure 3-6.

The compressive strength of the test specimen is calculated by dividing the maximum load

attained from the test by the cross-sectional area of the specimen, as shown by the following

equation:

p. 4p (3-1)

i -rr e-D2
Where









f is ultimate compressive strength of cylinder in psi;


p, -is ultimate compressive axial load applied to cylinder in lbs;

D is diameter of cylinder specimen in inch.

The average value of compressive strength from three cylinders will be taken as the

compressive strength of the concrete.


















Figure 3-6 Typical failure modes of concrete cylinders in compression test

3.6.2 Splitting Tensile Strength Test (or Brazilian Test)

Splitting tensile strength test is simple to perform than other tensile tests, such as flexural

strength test and direct tensile test. The strength determined from splitting tensile test is believed

to be close to the direct tensile strength of concrete. In this study, the testing procedure of ASTM

C 496 standard was followed in running the splitting tensile strength test. A 6"x 12" cylindrical

specimen, which is identical to that used for compressive strength test, with four lines drawn on

the sides of specimen to mark the edges of the loaded plane to help align the test specimen before

the load was applied, is placed with its axial horizontally between the platens of a testing

machine. Figure 3-7 shows the loading configuration for this test. As shown in Figure 3-7, two









strips of plywood as packing material, 3mm thick and 25mm wide, are interposed between the

cylinder and the platens so that the force applied to the cylinder can be uniformly distributed.

Then, the load will be applied and increased until failure by indirect tension in the form of

splitting along vertical diameter takes place.

61-__u Plywood

12"



ttttttttttttttt t

Figure 3-7 Loading configuration for splitting tensile test

The splitting tensile strength of a cylinder specimen can be calculated by the following

equation:

2p.
T. = (3-2)
1 /. D
Where

T splitting tensile strength of cylinder in psi;

p, -maximum applied load to break cylinder in lbf.

/ -length of cylinder in inch;

D diameter of cylinder in inch.

The splitting tensile strength of concrete will take the average value of splitting tensile

strengths of three cylinders.

Due to the sensitivity and susceptibility of the splitting tensile strength to the effects of

internal flaws, such as voids, the results of some splitting tensile strength tests may be unusually

low and may need to be discarded. For this reason, five extra concrete cylinders were prepared

for use in repeating this test if needed.









At last, the same curing conditions as those for the compressive strength test were used for

the splitting tensile strength test. Three replicate specimens were tested at each of the curing

times, which were 3, 7, 14, 28, 56, and 91 days. A total of 18 specimens per concrete mixture

were tested for splitting tensile strength.

3.6.3 Elastic Modulus Test

The testing procedure of ASTM C 469 standard was followed to determine the elastic

modulus of the concrete specimens. In this method, the chord modulus of elasticity of concrete

cylinders is determined when a compressive load is applied on a concrete cylinder in the

longitudinal direction.

A strain gage will be attached on the concrete cylinder to measure the deformation of the

concrete cylinder during a compression test. The load and deformation data were recorded by

means of a computer data acquisition system. A MTS machine, as shown in Figure 3-8, controls

the loading rate by controlling displacement automatically.

Prior to the test for modulus of elasticity, one of the three concrete cylinders was broken

first to determine the compressive strength of concrete in accordance with ASTM C39 standard.

Then, 40% of ultimate compressive strength of concrete specimen was applied on the other two

concrete cylinders to perform the elastic modulus test. The cylinders for the modulus of

elasticity test were loaded and unloaded three times. Then, the data from the first load cycle

were disregarded. The average value from the last two load cycles was recorded as the elastic

modulus of the concrete. Since the elastic modulus of concrete will vary with the age of concrete,

the elastic modules of concrete at the ages of 3, 7, 14, 28, 56, and 91 days were evaluated.

Throughout the test, the ambient temperature and relative humidity were maintained at 73 F and

100%, respectively.





























Figure 3-8 MTS system for elastic modulus and compressive strength test

3.6.4 Shrinkage Test

For the concrete mixtures with either Miami Oolite limestone aggregate or Stalite

lightweight aggregate, six 6"x 12" concrete cylinders were made to evaluate their shrinkage

behavior under two distinct curing conditions. Three cylinders were cured for 7 days in a moist

room, and then followed by a room condition curing for another 7 days. Another three cylinders

were cured for 14 days in a moist room, and then cured for another 14 days in room condition.

For concrete mixtures with Georgia granite aggregate, their shrinkage behaviors were

investigated under just one curing condition, i.e. moist curing for 14 days, followed by curing in

room condition for 14 days.

Three pairs of gauge points, which were spaced 10 inches apart, were placed on each of

concrete cylinder. A gauge-point guide was used to position the gauge points on the plastic

cylinder mold before the concrete was cast. Figure 3-9 shows a picture of the concrete with the

gauge points attached on them after the molds have been removed.




























Figure 3-9 Cylindrical specimen with gage points installed

A digital mechanical gauge was used to measure the change in the distance between the

gage points as the concrete cylinder shrinks. The digital mechanical gauge has a resolution of

0.0001 in.

Three sets of measurements were taken from each specimen. A total of nine sets of

measurements were taken from the three replicate specimens for each concrete mixture.

Measurements were taken every day in the first two weeks, and then once a week up to

three months. The initial distance between the gauge points was measured immediately after

required curing time was fulfilled. Then, the shrinkage test was run under the condition of the

temperature of 73 F and 50% relative humidity. The shrinkage strain was taken as the average

of the nine readings from the three replicate cylinders, and can be expressed as follows:

1 9 (1. -1
E = 1- (3-3)
sh 9 1/
=1 0

Where

1, -Measured distance between ith pair of gage points


I i- IC~ur -rl It; -~L~ -









10 -Original distance between ith pair of gage points measured immediately after demoded.









CHAPTER 4
CREEP TEST APPARATUS DESIGN AND TESTING PROCEDURE

4.1 Introduction

This chapter describes the design of the creep test apparatus, and its auxiliary tools, which

include a gage-point positioning guide for positioning gage points on a creep test specimen, and

an alignment frame for aligning the specimens in a vertical direction. The creep testing

procedures are also described in detail in this chapter.

4.2 Creep Test Apparatus

4.2.1 Design Requirements of Creep Test Apparatus

In order to carry out the creep test program, a simple creep test apparatus was designed to

satisfy the following design requirements:

* Creep test apparatus should be capable of applying and maintaining the required load on
specimen, despite of any change in the dimension of the specimen.

* The bearing surfaces of the header plates shall not depart from a plane by more than 0.001
inch to insure even pressure distribution on the concrete test specimens.

* Several specimens can be stacked for simultaneous loading so that more measurements can
be made, and the reliability of test results will be increased by taking average of all the
measurements.

* The height between two header plates shall not exceed 70 inches. If the height between
two header plates is over 70 inches, the apparatus will not be easily operated manually.
Also, if the total height of the stacked test specimens is very high, the specimens may
buckle easily under load.

* The applied load should be controlled so that it will vary by less than 2% of the target
applied load.

* Means shall be provided to make sure that concrete specimens are centered properly and
vertical.

The designed creep test apparatus, which is spring supported system, is shown in Figure 4-

1. The detailed design of creep apparatus used in this study is presented as follows.









4.2.2 Design of Creep Apparatus

4.2.2.1 The determination of the maximum capacity of the creep Apparatus

In this study, the maximum design capacity of creep apparatus was determined according

to the maximum compressive strength (10 ksi) of concrete mixtures commonly used in Florida.

Creep test was run under the loading condition of 50% of compressive strength of concrete on

6"x 12" cylindrical concrete specimens. Thus, the maximum load applied to the creep frame can

be computed as:

Pmax = 0.5 x 10000 x tr x 32 = 1413001bf

If a 4"x 8" cylindrical concrete specimen is used, the creep test can be run on the concrete

with compressive strength as high as 22 ksi.

4.2.2.2 The design of springs

The spring constant of the larger spring (k,) was selected as 9822 lbf/in, while the spring

constant of the smaller spring (k2) was selected as 3314 lbf/in. The maximum travel distance

(A) for both springs is 1.625 in. If nine sets of springs are used, the maximum load (Pspnng ) that

the springs can hold can be calculated to be:

Psrng =9x(k +k)xA = 1.92x105lbf>Pmax- --OK

Thus, the spring capacity is ok.

It is of importance to mention that the design maximum travel distance of spring can not be

more than the maximum travel capacity of the springs in order to maintain the load on specimen

constant, and keep the frame stable.
















Load Cell


Hydraulic
Jack

Circular
Steel
Plate

01.125in'
Gauge


Concrete 1
Cylinder




Circular
Steel

Springs







01.25in














Figure 4-1 Creep test apparatus


t'l


- "


tc


4o
00

* S


18in


N










4.2.2.3 Design of header plate


I II

--'------ ..'-- .-- -- -----







I -: -- --------- -



,II :I!
.. . . : -'- _Z o e ...... ... ..


6i 6in I
II, I 1 .25in






Figure 4-2 Boundary conditions used for finite element analysis

In order to apply load uniformly to the test specimens, the deflection of header plate should

not deviate too much for a plane surface when the specimens are loaded. The required thickness

of the header plates was determined using a finite element analysis. The steel plate was modeled

as an isotropic elastic material with an elastic modulus of 29,000 ksi and Poisson's ratio of 0.30,

which are typical properties of steel. The plate was modeled as fixed from rotation about the x, y

and z axis along the four boundary lines along the four holes on the steel plate as shown in

Figure 4-2.

The loading zone was modeled as a circular area identical to the cross sectional area of a 6-

inch diameter concrete cylinder. The maximum load used in the analysis had a pressure of 5000

psi, which is 50% of the maximum compressive strength of concrete investigated in this study.

























Figure 4-3 Finite element mesh used in the header plate analysis

A TIME 1.0DO DISP HAG 4619. Z
A DISPLACEMEN7
D TIME 1.000
I 0 o.oo
O.CO39M
NI .
A- 0.002P9
0.0003



MAXIMUM
MNIMUM




Figure 4-4 Contour plot of deflection of header plate

The finite element mesh used in the analysis consisted of triangle elements and rectangular

elements as shown in Figure 4-3. The header plate with a thickness of 1.5 inches was analyzed.

The deflection contour plot is shown in Figure 4-4. As we can see from Figure 4-4, the deflection

from center of header plate to the position 3 inches away from center changes from 0.00408 to

0.0033 inch. In other words, if the test specimens are loaded to a maximum pressure of 5,000

psi, the deflection of steel plate will differ by less than 0.00078 inch, which is less than 0.001

inch. Thus, a header steel plate with a thickness of 1.5 inches was determined to be adequate

and selected for use.


A 1IME 1.0~ DISP HAG 4698. Z
D
I
NI
A









4.2.2.4 Determination of the size of steel rod

When the concrete specimens are loaded in the creep frame, each of the four steel rods will

carry one quarter of total load. The steel rods are 1.125 in. in diameter and are made of high-

strength alloy steel with yield strength of 105,000 psi. If the concrete specimens are loaded up to

the maximum capacity of the creep apparatus of 141,300 lbf, the maximum stress in the steel

rods would be equal to:

141300
= 35556psi
4.0.56252 2-

This maximum possible stress in the steel rods is less than half of the yield strength of the

steel rod, which is 105,000 psi. Thus, the selected steel rod meets the design requirements.

4.2.2.5 Stress relaxation due to the deflection of header plate and creep of concrete

When the full capacity of creep frame is used, the total stress released due to the plate

deflection can be approximated as follows:

Prelaxed = Adeflecton x kol = 0.0041 x 13136 x9 = 485pounds

Where Adeflecton is the maximum deflection of header plate, and kpng is the elastic

constant of spring.

While according to the design requirement, the allowable load relaxation is

141300 x 0.02 = 2826pounds

In addition, since partial load will be relaxed due to the creep of concrete, the applied load

to the concrete specimen should be adjusted in order to keep the load the same as the initially

applied one. To have an error of less than 2,826 lbf in the applied load, the following inequality

has to be satisfied:

36 cr. ktota + 4851bf < 28261bf

Solving the above inequality, we obtain that









s,, < 0.0006

This means that the applied load should be adjusted at every 0.0006 increment of creep

strain. Otherwise, the load relaxed would be more than 2826 lbf, the allowable maximum load

relaxation.

4.3 Design of Gage-Point Positioning Guide

Three pairs of gage points with a gage distance of 10 inches are to be placed in each test

concrete specimen. A gage-point positioning guide, as shown in Figure 4-5, was designed for

use in positioning the gauge-points on the plastic cylinder mold. By inserting a 6"x 12" cylinder

mold into gage-point position guide and tightening the six screws on the guide, the precise

locations for the three pairs of gage points, with a gage distance of 10 inches, can be marked

conveniently on the mold. Three lines of gage points are uniformly distributed with 120 angle

along the periphery of specimen. The use of the gage positioning guide is of great importance

because the maximum travel distance of mechanical strain gage is 0.4 in. The mechanical strain

gage can not be used to measure a distance of more than 10.4 inches. Thus it is very important

that the two gage points be place at an exact distance of 10 inches from one another. Figure 4-6

shows a picture of the gauge-position guide. Figure 4-7 shows a picture with a plastic cylinder

inside the gauge-position guide.

4.4 Design of Alignment Frame

An alignment frame was designed and constructed to be used to align the concrete

specimens in a vertical direction when they are placed in the test frame. Figure 4-8 shows the

design of the alignment frame. The alignment frame consists of one piece of angle steel and one

piece of channel steel with three pieces of 0.5"x2"x 10" steel plates welded on them respectively.

They are connected together by using 6 steel rods. The use of the alignment frame is described

in creep testing procedure.













D 6.05"


o


















Figure 4-5 Design of Gage-point positioning guide





























Figure 4-6 Gauge position guide


Figure 4-7 Plastic cylindrical mold inside gauge position guide


I









4.5 Mechanical Strain Gauge

A mechanical strain gauge, as shown in Figure 4-9, was used to measure the distance

change between two gauge points. The instrument frame is made of aluminum alloy and has five

master settings of 2", 4", 6", 8", and 10" that are easily set for gauging. The digital indicator has

a minimum graduation of 0.0001". In this study, the master setting of 10" was selected so that the

mechanical strain gage is suitable for the measurement of longitudinal strain to the nearest 10

millionths. In addition, the effective range of displacement measurement is 0.3".

4.6 Other Details on Creep Apparatus

For each test frame, three 6"x 12" cylindrical specimens are placed on top of one another

and tested under the same load. The load is applied by means of an electronic hydraulic jack

(with a maximum capacity of 200,000 lbs) and monitored by a load cell with a digital readout

indicating the load applied. The load cell has a capacity of 200 kips, and the minimum readable

digit of 10 pounds. When the desired load is reached, the nuts on the threaded rods is tightened

so that they are snugly pressing against the plate underneath the hydraulic jack so as to hold the

plate in that position, and thus holding the applied load. After the nuts are positioned properly to

hold the applied load, the jack and the load cell can be removed from the test frame and used to

load another test frame. The springs at the bottom of the creep frame help to maintain the balance

of creep frame as well as a constant load on the specimens despite any change in its length, as the

concrete specimens creep under load. Up to 9 sets of springs can be used in this test frame.

Figure 4-10 shows the positions of the springs in the test frame. Each set of springs consists of a

smaller spring sitting inside a larger spring. In addition, the springs should be manufactured so

that both ends of spring should be flatted, and nine sets of springs should have the same height,

and positioned symmetrically to keep load distribution evenly. In doing so, there is no spherical

bearing device needed to guarantee the load to be evenly transferred to the specimens.









As the concrete specimens are loaded in the creep frame, the rectangular steel plates, which

are at the top and bottom of the test specimens, are deflected slightly. To keep the loading

surfaces flat and the test specimens vertical when the load is applied, two 1-inch thick circular

steel plates with a diameter of 6 inches are placed on the top and bottom of the stack of concrete

test specimens, as shown in Figure 4-1. Both surfaces of the circular plate should be polished to

avoid of any uneven pressure on the concrete cylinder.

4.7 Creep Testing Procedure

1. Install gauge points on plastic cylindrical molds using the Gauge Position Guide. Each
creep test specimen contains three pairs of gage points installed on concrete cylinder
using Gauge position guide, which are placed 10 inches apart from each other.

2. Place the fresh concrete in the plastic cylinder molds. Place the fresh concrete into plastic
cylinder in three layers. Consolidate each layer with 45 seconds of vibration on a
vibrating table. After consolidation, the top surface of concrete should be finished gently.
This is a very important detail in making specimen to avoid cracking around gauge insert
as shown in Figure 4-11. If too much pressure is applied to finish the surface, gauge
inserts may be pushed downward because the plastic cylinder is not very stiff and can not
keep the gauge inserts from being pushed downward. Once pressure is released, the
gauge insert will return to its original position, while concrete can not because plastic
deformation can not be recovered. Thus, some space between gauge insert and concrete
will be created and it will affect the measurement.

3. Demold the concrete specimens after 24 hours of curing. Place the specimens in a moist
room to cure for the required time.

4. Grind both end surfaces of each concrete cylinder. Both end surfaces of specimen should
be ground in order to make them even, as shown in Figure 4-12.

5. Cap both ends of each cylinder using sulfur mortar to make end surfaces smooth and
even.

6. Using the alignment frame designed for this study to stack the three replicate specimens
vertically on top of one another.

7. Put two circular plates on top of concrete cylinder as well as at the bottom of concrete
cylinders.


















0.5in







- - - - - -
----- ---
. C)


F ~ ---- ---------------I
r - 3 - -. . !


II I
i II




:4 10.OOin
i I r


4 0.5in


- '0.5in


I I
I I
I I
I I
I I
I I
I I


1.5M


Figure 4-8 Schematic of alignment frame design






87


0
O
o*


0T


0T


:1 75jn
II I


__iljlllllllg~jg~jg~gj~


_- DO.5in
? --- ---------------


lllllllllllllllII I rTT TT TT TI II






















re, r Me hac gag





Figure 4-9 Mechanical gauge


Inside Outside

Large
02.94i 05.50in






Small -
spring









6in

12in


Figure 4-10 Positioning springs on the bottom plate












| | | Pressure applied while finishing


Gauge
Insert


Space
Created


Figure 4-11 Cracking around gauge insert


Figure 4-12 Concrete cylinder with both end surfaces ground


8. Adjust the creep frame and concrete specimens to make sure the specimens are centered
and vertical. The creep frame can be adjusted through moving the header plate back and
forth with the nuts on the top of the plate. As shown in Figure 4-13, the centers of header
plate and the plate on the top of springs are marked. On each plate is also marked a 3-
inch diameter with 8 mark points along the boundary of the circle. If the concrete column
consisting of three cylinders is placed so that it lines up with the circles on the header and
the bottom plates, then the concrete cylinders are centered and vertical.

9. After the concrete specimens are centered, turn the nuts supporting the header plate
downward at least 1.65 in. away from the bottom of header plate to avoid the header plate
contacting with the nuts once load is applied. Then, tighten the four nuts on the top of
header plate slightly to hold the centered concrete specimens.










Header Plate


Mark .
Point 1.65in



Circular
Plate




(D-6in


Figure 4-13 How to center the specimens into creep frame


10. Set up a hydraulic jack and load cell in the creep frame, and check the position of
hydraulic jack to make sure that it is co-axial with concrete specimens in order to avoid
loading the concrete specimens eccentrically. As shown in Figure 4-14, in order to make
the hydraulic jack co-axial with concrete specimens, the center of the header plate has
also been marked on the top side. A circle with diameter identical to the diameter of jack
cylinder has also been drawn on top of the header plate, with 4 marks hammered along
the boundary of the circle

11. As shown in Figure 4-15, check the plate on the top of load cell to make sure that the
plate is level. Then, tighten slightly the four steel nuts holding the top plate.


12. Preload the frame up to 500 lbf to properly seat the concrete test specimens in the creep
frame.

13. Take the initial measurements, which are the initial distance between two gauge points.

14. Apply the load through the electronic hydraulic jack up to the target load. It is strongly
recommended to use electronic hydraulic jack because of several advantages in using
electronic hydraulic jack. Firstly, by using electronic hydraulic jack, the load can be
applied to the loading frame continuously. Secondly, since the electronic hydraulic jack
can apply load on the cylinder within 1 minute, the instantaneous measurements can be
taken within seconds immediately after the loading procedure was completed. Thus, the
instantaneous measurement taken in this way is very close to the true elastic deformation.
Thirdly, in using the electronic hydraulic jack, the dynamic effect, which can cause the








cylinders to break easily, can be avoided. In addition, less effort is needed to load frame
in comparison with using manual hydraulic jack, which takes hundreds of pushes to reach
the desired load level.


Jack
Cylinder


Mark
Point


Figure 4-14 How to center the hydraulic jack cylinder


Jack
Cylinder


Load cell


Figure 4-15 Leveling the plate on the top of load cell
15. Immediately after the target load is reached, tighten the four nuts on the top of the header
plate to hold the load on the specimens.


r\ff 1 0









16. Take instantaneous measurements using the digital mechanical gage immediately after
loading. Then take the measurements in 1 hour, 3 hours and 6 hours. Then every day in
the first two weeks, and then once a week until 91 days, and then once a month if tests
were kept going.

17. Adjust load at every 0.0008 increment of creep strain to keep the load loss due to creep
relaxation less than 2% of total load applied at the beginning.

It deserves to emphasize again that it is important to take the first set of readings as quickly

as possible in order to obtain a more accurate instantaneous deformation of the concrete.

Otherwise, substantial early creep deformation may have taken place before the initial readings

can be taken. The first set of readings can be taken within 3 minutes.

The creep strain was calculated by subtracting the shrinkage strain from the total strain as

follows:


9 1 / 1 -1I
ET T


S 0(i) 0(i)

Where

Ec Creep strain of concrete

cE The sum of creep strain and shrinkage strain

Es Shrinkage strain of concrete

I The measurement taken from the ith pair of gage points for creep test

IT The initial length of the ith pair of gage points for creep test


Is The measurement taken from the ith pair of gage points for shrinkage test

Is The initial length of the ith pair of gage points for shrinkage test

i -No. of pair of gage points from 1 to 9









The creep coefficient, which is used in concrete structure design, is calculated by taking

the ratio of creep strain of the concrete at the testing age to elastic strain of concrete at the same

curing age. It can be expressed as follows:

sC
C C (4-2)
cr


Where

C, Creep coefficient

Ec Creep strain of concrete

EE Elastic strain of concrete

Creep modulus, Ec, is computed dividing the applied stress by the total strain without

including shrinkage strain, as shown by Equation 4-3.


E (4-3)
c E +

4.8 Summary on the Performance of the Creep Apparatus

The creep apparatus designed in this study is capable of applying and maintaining the

required load on the test specimens. Three specimens can be stacked for simultaneous loading.

The unevenness of the deflection of bearing surface of the header plates is less than 0.001 in. and

the pressure distribution on the concrete specimens varies by less than 0.026%, or 1.5 psi. Load

can be applied to a precision of 10 lbs, as a load cell with resolution of 10 lbs is used control the

applied load. The mechanical gauge used is able to measure longitudinal strain to a precision of

0.00001. Strains are measured on three gage lines spaced uniformly around the periphery of the

specimen. An electronic hydraulic pump system is used to apply load to the creep frame. This









enables the loading process to be done in seconds, and instantaneous strains can measured from

creep test within a short time after loading.

The gauge point position guide, which has been designed to position gauge points on a

plastic cylindrical mold, is a very effective and important auxiliary tool in preparation of test

specimens. It enables the placement of gauge points at accurate locations on the test specimen so

that the maximum travel distance of mechanical gauge will not be exceeded and measurement

error can be reduced.

The alignment frame, which has been designed to align concrete specimens vertically in

the creep frame, makes the job of stacking three concrete specimens together for testing possible.

Experimental results indicate that creep apparatus designed in this study is effective,

reliable and practical. It can be used to run creep test on concrete with a maximum compressive

strength up to 10,000 psi if 6"x 12" cylinder specimens are used. If 4"x8" cylinder specimens are

used, the maximum compressive strength of the concrete can be as high as 22,000 psi.










CHAPTER 5
ANALYSIS OF STRENGTH TEST RESULTS

5.1 Introduction

This chapter presents the results from compressive strength, splitting tensile strength and

elastic modulus tests on the 14 concretes mixes evaluated in this study. The effects of various

factors on strength are discussed. The prediction equations establishing inter-relationship

between compressive strength and splitting tensile strength are given. The prediction equations

relating compressive strength to elastic modulus are also presented.

5.2 Results and Analysis of Compressive Strength Tests

The average compressive strengths at various curing times of the fourteen concrete mixes

evaluated are presented in Table 5-1. The individual compressive strength values are shown in

Table A-i in Appendix A.

Table 5-1 Compressive strength of the concrete mixtures evaluated (psi)
Age of Testing (days)
Mix Number W/C Fly ash Slag Age of T g
3 7 14 28 56 91
Mix-IF 0.24 20% 8077 8572 8993 9536 10771 11267
Mix-2F 0.33 20% 4077 4658 6028 6506 6838 7607
Mix-3F 0.41 20% 5289 6470 7567 8241 8449 9426
Mix-4F 0.37 20% 5712 6919 7114 7236 8996 9271
Mix-5S 0.33 50% 5554 7235 8248 8832 9139 9456
Mix-6S 0.36 50% 6375 7699 8587 9111 9529 9661
Mix-7S 0.41 70% 4324 5374 5927 6392 6794 6917
Mix-8S 0.44 50% 4795 6114 6939 7525 8119 8208
Mix-9LF 0.31 20% 3039 3941 5136 5929 6690 6961
Mix-O1LS 0.39 60% 1467 2191 2937 3744 4312 4727
Mix-2GF 0.33 20% 3885 4952 5807 6469 6952 7201
Mix-3GF 0.41 20% 3818 5151 6137 7262 7782 8041
Mix-5GS 0.33 50% 2961 4692 5692 7008 7854 8105
Mix-7GS 0.41 70% 2267 4303 5222 6612 6741 7233


5.2.1 Effects of Water to Cement Ratio and Water Content on Compressive Strength

In engineering practice, the strength of concrete at a given age and cured in water at a

prescribed temperature is assumed to depend on primarily on water to cementitious materials

ratio and the degree of compaction. In this study, for the eight selected concrete mixtures using










Miami Oolite limestone aggregate, the effects of water to cementitious materials ratio on

compressive strength at ages of 28 days and 91 days are shown in Figure 5-1 and Figure 5-2

respectively. The graph of compressive strength versus water to cementitious materials ratio is

approximately in the shape of a hyperbola. Compressive strength tends to decrease as water to

cementitious materials ratio increases.

Water content is another important factor influencing the strength of concrete because the

higher the water content, the more porous the hardened concrete tends to be. As shown in Figure

5-3 and Figure 5-4, compressive strength of concrete decreases dramatically as water content

increases.


16000

14000

12000

10000

8000

6000

4000

2000


0 0.1 0.2 0.3 0.4
Water to Cementitious Materials Ratio


0.5 0.6


Figure 5-1 Effects of water to cementitious materials ratio on compressive strength at 28 days












16000


14000


12000


10000


8000


6000


4000


2000


0


0 0.1 0.2 0.3 0.4
Water to Cementitious Materials Ratio


0.5 0.6


Figure 5-2 Effects of water to cementitious materials on compressive strength at 91 days


16000


14000


12000


10000


8000


6000


4000


2000


0


220 230 240 250 260 270

Water Content (Ibs/yard3)


Figure 5-3 Effects of water content on compressive strength at 28 days


O


O
0 o

O
^^o

0 8 ^


280 290


o


0 0 0

0 a
00


i i i i i i












16000


14000


12000


0 10000


S8000


. 6000


E 4000


2000


0


220 230 240 250 260 270 280 290
Water Content (Ibs/yard3)



Figure 5-4 Effects of water content on compressive strength at 91 days

5.2.2 Effects of Aggregate Types on Compressive Strength

The influence of coarse aggregate type on compressive strengths of four concrete mixtures


is shown in Figures 5-5 through 5-8. Figure 5-5 shows the compressive strength development


with time for Mix-2F and Mix-2GF containing 20 % fly ash. Both concrete mixtures have


identical mix proportions other than the different types of aggregate. Miami Oolite limestone


aggregate was used for Mix-2F, and Georgia granite aggregate was used for Mix-2GF. It can be


seen that the compressive strength of Mix-2F is comparable to that of Mix-2GF at various curing


ages. For Mix-5S and Mix-5GS, the different aggregate types gave considerable impact to the


compressive strength. As can be seen from Figure 5-6, Mix-5GS using Georgia granite aggregate


had very much lower compressive strength than Mix-5S using Miami Oolite limestone aggregate


at various ages. The same phenomenon can also be observed from Mix-3F and Mix-3GF, as


shown in Figure 5-7, and Mix-7S and Mix-7GS, as depicted in Figure 5-8.


O

O
O
O O
o
o
o









According to the concrete mixtures investigated in this study, the concrete mixtures using

Miami Oolite limestone as coarse aggregate developed higher compressive strength than those

using Georgia granite as coarse aggregate.

The cause can be attributed probably to the shape of aggregate, surface characteristic and

other physical properties such as water absorption. Most of aggregate particles of Georgia granite

have elongated and flaky shape, which is not desirable to be used for high strength concrete

because flaky particles tend to be oriented in one plane, with bleeding water and air voids

forming underneath. Thus, the interfacial transition zone between aggregate and hardened mortar

may be weaker causing the compressive strength of concrete to be lower. Most of the aggregate

particles of Miami Oolite limestone have spherical shape, which is preferred for durable concrete

mix because the spherical aggregate particles have lower surface to volume ratio, and they will

pack better in a mortar matrix.

The surface texture of Georgia granite aggregate is very dense and smooth, which may

have a disadvantage in developing tight interlock between aggregate and mortar matrix. Miami

Oolite limestone has a very rough texture and appreciable voids on the surface, and thus strong

interlock can be formed since the cement slurry can penetrate into those voids.

The water inside limestone aggregate can migrate outward as cement hydration proceeds

since the relative humidity gradient will be generated between internal aggregate and mortar.

This water may possibly provide the water needed for hydration of the cement as moisture is lost

through evaporation to the environment.

































Figure 5-5 Effects of coarse aggregate type on compressive strengths of Mix-2F and Mix-2GF


Figure 5-6 Effects of coarse aggregate type on compressive strength of Mix-3F and Mix-3GF

































Figure 5-7 Effects of coarse aggregate type on compressive strength of Mix-5S and Mix-5GS


Figure 5-8 Effects of coarse aggregate type on compressive strength of Mix-7S and Mix-7GS










5.2.3 Effects of Fly Ash and Slag on Compressive Strength of Concrete

Fly ash and slag are used mandatorily in Florida mainly for concrete durability purpose.

The investigation on their effects on the development of compressive strength of concrete

mixture is of great importance because of significance of their use in concrete. In this study, fly

ash was as a cement substitute in an amount of 20% of total cementitious materials by mass, and

slag was in an amount of 50%-70% of total cementitious materials by mass. The strength

development characteristics of fly ash concrete and slag concrete with time were normalized as

the ratio of compressive strength at various curing ages to the compressive strength at 91 days

and the normalized values are presented in Table A-2 in Appendix A.

The strength development characteristics of two typical fly ash concretes and two slag

concretes are illustrated in Figure 5-9. As can be seen from Figure 5-9, the fly ash concretes had

significant strength gain from 28 days to 91 days, while the slag concretes had already achieved

more than 90% of their 91-day strength at 28 days.





c 0.95 "





o_ 0.85
'- //





SMx-1F-Fly ash-W/C=0 24

7 0.80 _- -Mx-6S-Slag-W/C=0 36
o --X- Mlx-5S-Slag-W/C=0 33
0)

S0.75


0.70
0 20 40 60 80 100
Ages (days)


Figure 5-9 Effects of fly ash and slag on compressive strength of concrete









5.2.4 Prediction of Compressive Strength Development

Knowledge of the strength-time relation is of great importance when a structure is put into

service, i.e. subjected to full loading condition and for long time duration. The gain in strength

after 28 days can be taken into consideration in design. In some other cases, for instance, in

precast or prestressed concrete, or when early removal of formwork is required, the strength at

early ages needs to be known.

According to ACI 209R-5, a general equation for predicting compressive strength at a

given age has the following form:

fco= a+j -t c28 (5-1)

Where a in days and / are constants, f28 is compressive strength of concrete at 28 days,

and t in days is the age of concrete.

Equation 5-1 can be transformed into


fc(t) = fu (5-2)
Sa/3+t cu
Where ac/l is the age of concrete in days at which one half of the ultimate compressive

strength of concrete, fc is reached. For the tests using 6xl2in cylinders, type I cement and

moist curing condition, two constants, the average values of a and f, are equal to 4.0 and 0.85

respectively. The ranges of a and / in Equation 5-1 and 5-2 for the normal weight, sand

lightweight, and all lightweight concretes (using both moist curing and steam curing, and type I

and III cement) given by Branson, D.E.; Meyers, B.L.; and Kripanarayanan, K.M[Branson, D.E

et al. 1973] are: a=0.05 to 9.25, and / =0.67 to 0.98. They were obtained from the tests on 88

6xl2in concrete cylinders and cited by ACI 209 COMMITTEE REPORT in 1996. As mentioned

in ACI 209R-4, the values of a and / are not applicable to the concretes containing pozzolanic









materials, such as fly ash and slag. Furthermore, ACI 209R-4 indicates that the use of normal

weight, sand lightweight, or all lightweight aggregate does not appear to affect a and /

significantly.

In this study, regression analysis using the form of ACI 209R-5 equation (as shown in

Equation 5-1) was performed on the results of compressive strength tests on the 432 concrete

cylinders from this study to determine the a and / values for each mix. Table 5-2 shows the a

and /values for all the mixes from this analysis. The detailed results of this analysis are

presented in Table 5-3. Table 5-4 presents the average a and / values of the different concrete

f'(t) f'(t)
mixes as grouped by aggregate type. Table 5-4 also shows the time ratios ( and f at
f"28 f-

different during times for these different groups of concrete mix in comparison with the

corresponding values as predicted by the ACI-209R equation.

As can be seen from Table 5-2, there is substantial difference between a and / values

among the different mixes. For the concrete mixtures using Miami Oolite limestone coarse

aggregate, the value of a varies from 1.1 to 2.6, and its average value of 1.89 is significantly

lower than 4.0 recommended by the ACI-209 code; and the value of 3 is in the range of 0.82 to

0.93, and its average value of 0.90 is slightly higher than 0.85 given by the ACI code. This

means that the concrete mixes using Miami Oolite limestone aggregate and fly ash and slag tend

to develop strength faster than the concrete mixtures as predicted by the ACI-209R equation.

For the concrete mixtures using Georgia granite aggregate, the value of a varies from 2.6

to 5.3, and its average value of 4.12 is close to 4.0 recommended by the ACI code; and the value

of P is in the range of 0.82 to 0.89, and its average value of 0.86 is agreeable with 0.85 given by









the ACI code. Thus, this indicates that the concrete mixtures using Georgia granite aggregate had

similar strength development as predicted by the ACI equation.

For the concrete mixtures using the Stalite lightweight aggregate, the average value of ac is

5.5 and the average value of 3 is equal to 0.78. This indicates that coarse aggregate type can have

significant effects on the strength development process.

5.3 Analysis of Splitting Tensile Strength Test Results

The average splitting tensile strengths at various curing times of the fourteen concrete

mixes evaluated are displayed in Table 5-5. The individual splitting tensile strength values are

shown in Table A-3 in Appendix A.

5.3.1 Effects of Water to Cement Ratio on Splitting Tensile Strength

Water to cementitious materials ratio has a significant effect not only on compressive

strength, but also on splitting tensile strength.

Figure 5-10 and Figure 5-11 show the effect of water to cementitious materials ratio on

splitting tensile strength of concrete at 28 days and at 91 days respectively. They indicate that

splitting tensile strength decreases as water to cementitious materials ratio increases.

5.3.2 Effects of Coarse Aggregate Type on Splitting Tensile Strength

The effect of coarse aggregate types on splitting tensile strength of concrete was evaluated

on four concrete mixtures. Mix-2F, Mix-3F, Mix-5S, and Mix-7S have Miami Oolite limestone

as coarse aggregate, and Mix-2GF, Mix-3GF, Mix-5GS, and Mix-7GS have Georgia granite as

coarse aggregate. Mix-2F and Mix-2GF, Mix-3F and Mix-3GF, Mix-5S and Mix-5GS, and Mix-

7S and Mix-7GS have identical mix proportions with the exception that a different coarse

aggregate of the same volume was used. As shown in Figures 5-12 through 5-15, the effects of

coarse aggregate types on splitting tensile strength of concrete are quite significant. In

comparison with Mix-2F, Mix-3F, Mix-5S and Mix-7S, the four mixtures using Georgia granite











Table 5-2 Results of regression analysis for prediction of compressive strength development
using ACI 209 equation


a
by ACI

1.10
2.67
2.25
1.57
2.04
1.57
1.79
2.15 4
4.20
6.74
2.64
3.51
4.99
5.35


Square root of Absolute
S p sum of squares by
by ACI
b A Modified ACI Equation
0.90 673
0.89 371
0.90 343
0.83 676
0.92 67
0.94 125
0.92 275
0.91 0.85 150
0.82 230
0.74 131
0.89 180
0.88 197
0.82 160
0.86 269


Square root of Absolute
sum of squares by ACI
Equation
1904
541
792
1571
886
1214
1698
726
261
385
445
257
311
547


Mix

M-1F
M-2F
M-3F
M-4F
M-5S
M-6S
M-7S
M-8S
M-9LF
M-10LS
M-2GF
M-3GF
M-5GS
M-7GS










Table 5-3 Results of regression analysis on the prediction of compressive strength development using ACI 209 equation


Results i M-1F M-2F M-3F M-4F M-5S M-6S M-7S

a 1.098 2.673 2.252 1.573 2.039 1.574 1.792
P 0.9017 0.8886 0.9043 0.8261 0.9231 0.9363 0.9213
a(SE) 0.3482 0.4901 0.3071 0.4732 0.05387 0.08311 0.1261
P3(SE) 0.03574 0.0344 0.02365 0.04108 0.004384 0.007592 0.01085
0.2026 to 1.413 to 1.463 to 0.3568 to 1.901 to 1.361 to 1.468 to
a (95%CI) 1.993 3.933 3.042 2.790 2.178 1.788 2.116
0.8098 to 0.8002 to 0.8435 to 0.7205 to 0.9118 to 0.9168 to 0.8934 to
p (95%CI) 0.9935 0.9770 0.9651 0.9317 0.9344 0.9558 0.9492
DOF 5 5 5 5 5 5 5
R2 0.9736 0.9801 0.9902 0.9625 0.9997 0.9989 0.9978
ASS 2266000 769806 589302 2168000 22420 73904 75810
Sy.x 673.3 392.4 343.3 658.4 66.96 121.6 123.1
Points Analyzed 7 7 7 7 7 7 7



Table 5-3 Continued
Six Mix-2GF Mix-3GF Mix-5GS Mix-7GS
M esuts M-8S M-9LF M-10LS Mix-2GF Mix-3GF Mix-5GS Mix-7GS
Results


ca 2.152
P 0.9054
a(SE) 0.1427
P (SE) 0.01122
1.786 to
a (95%CI) 2.519
0.8765 to
p (95%CI) 0.9343
01.9343
DOF 5
R2 0.9978
ASS 112202
Sy.x 149.8
Points Analyzed 7


4.203
0.8239
0.4144
0.02191
3.138 to
5.268
0.7675 to
0.8802
5
0.9927
263786
229.7
7


6.744
0.74
0.5222
0.01987
5.402 to
8.087
0.6889 to
0.7911
5
0.9949
85405
130.7
7


2.635
0.8916
0.2175
0.0154
2.076 to
3.194
0.8520 to
0.9312
5
0.996
151718
174.2
7


3.512
0.8777
0.2677
0.01618
2.824 to
4.200
0.8361 to
0.9193
5
0.996
193402
196.7
7


4.993
0.815
0.2823
0.01346
4.267 to
5.718
0.7804 to
0.8496
5
0.9975
128354
160.2
7


5.345
0.8554
0.4698
0.02215
4.137 to
6.552
0.7984 to
0.9123
5
0.9941
251535
224.3
7










Table 5-4 Values of the constants,a,
Time Type of Cement
Ratio Curing Type


P and c/1 and the time ratios from Equation 5-1 and 5-2
Aggregate a, 3 and Concrete ages (days)
type ca/ 3 7 14


Ultimate
28 56 91 in time


ACI 209R-4

Miami Oolite
Limestone

Granite


Stalite

ACI 209R-4
Miami Oolite
Granite
Stalite


a=4.00
3=0.85
a=1.89
P=0.90
a=4.12
P=0.86
a=5.50
3=0.78
c/P=4.71
c/P=2.10
c/P=4.79
c/p=7.05


0.46 0.70 0.88 1.00 1.08 1.12 1.18

0.65 0.85 0.97 1.00 1.07 1.09 1.11


0.45 0.69 0.87 1.00 1.07 1.10 1.16


0.38 0.64 0.85 1.00 1.14 1.19 1.28


0.39
0.59
0.39
0.29


0.60
0.77
0.59
0.50


0.75
0.87
0.75
0.67


0.86
0.93
0.85
0.80


0.92
0.96
0.95
0.89


0.95
0.98
0.95
0.93


1.00
1.00
1.00
1.00


Moist
cured


f (t)
fc28


f(t)


Moist
cured














Table 5-5 Splitting tensile strengths of the concrete mixtures evaluated (psi)


W/C Fly ash

0.24 20%
0.33 20%
0.41 20%
0.37 20%


Mix
Number
Mix-IF
Mix-2F
Mix-3F
Mix-4F
Mix-5S
Mix-6S
Mix-7S
Mix-8S
Mix-9LF
Mix-10LS
Mix-2GF
Mix-3 GF
Mix-5GS
Mix-7GS


20%

20%
20%


Slag


Age of Testing (days)


3
592
408
513
457
50% 442
50% 570
70% 426
50% 372
350
60% 212
352
382
50% 282
70% 245


1200



1000

U)





600
-D



U)
C
2 400



-) 200
Cl) 200


0 !
0.1 0.2 0.3 0.4 0.5 0.6
Water to cementitious Materials Ratio



Figure 5-10 Effects of water to cement ratio on splitting tensile strength at 28 days


0.33
0.36
0.41
0.44
0.31
0.39
0.33
0.41
0.33
0.41


0 0












1200



1000



800



600



400



200



0


0.1 0.2 0.3 0.4 0.5 0.6
Water to Cementitious Materials Ratio



Figure 5-11 Effects of water to cement ratio on splitting tensile strength at 91 days


O
0 0o
0
0 6

































Figure 5-12 Effects of aggregate type on splitting tensile strength of Mix-2F and Mix-2GF


Figure 5-13 Effects of aggregate type on splitting tensile strength of Mix-3F and Mix-3GF

































Figure 5-14 Effects of aggregate type on splitting tensile strength of Mix-5S and Mix-5GS


Figure 5-15 Effects of aggregate type on splitting tensile strength of Mix-7S and Mix-7GS









aggregate have significant lower splitting tensile strength. For example, Mix-3F has an average

splitting tensile strength of 731 psi at 91 days, while the splitting tensile strength of the

corresponding Mix-3GF is 624 psi. At 91 days, the splitting tensile strength of Mix-5S is 738 psi,

which is 16.8% higher than that of the corresponding Mix-5GS.

5.3.3 Effects of Fly Ash and Slag on Splitting Tensile Strength of Concrete

Fly ash and slag have significant effect on splitting tensile strength. In order to see the

effects of fly ash and slag on splitting tensile strength, the strength development characteristics

of splitting tensile strength was normalized as the ratio of splitting tensile strength at various

curing ages to the splitting tensile strength at 91 days and the normalized values are listed in

Table A-4 in Appendix A. As can be seen from Table A-4, the splitting tensile strengths of fly

ash concrete mixtures increase slowly in 28 days after demolding, and the 28-day splitting tensile

strength is around 85% of splitting tensile strength at 91 days, while the splitting tensile strength

of slag concrete increased very rapidly in 28 days after demolding, up to 94% of splitting tensile

strength at 91 days.

For example, the splitting tensile strength of Mix-2F at 91 days is 659 psi, increasing 21.6

percent in comparison with that at 28 days. Mix-3F has a splitting tensile strength of 73 psi at 91

days, increasing 17.1 percent in comparison with that at 28 days. But, for the concrete mixtures

with slag and limestone coarse aggregate, there is no appreciable increase in splitting tensile

strength after 28 days curing. For example, Mix-5S, Mix-6S, Mix-7S, and Mix-8S increase in

splitting tensile strength by less than 10% at 91 days as compared with that at 28 days. For the

concrete mixtures with Georgia granite aggregate, substantial increase in splitting tensile strength

after 28 days also happened to the mixtures with fly ash, while no significant increase was found

in concrete mixtures with slag. For two lightweight aggregate concrete mixtures, similar situation

can be observed as well.










The development characteristics of two typical fly ash concretes and two slag concretes

with time are shown in Figure 5-16.


1.00


S0.95
0o

- 0.90
cn

S0.85


0.80
Q.
c-

o 0.75


0.70


Time (days)


Figure 5-16 Effects of fly ash and slag on splitting tensile strength of concrete

5.4 Relationship between Compressive Strength and Splitting Tensile Strength

The compressive strengths of the concretes (as tabulated in Table A-1) were plotted against

the corresponding splitting tensile strengths (as tabulated in Table A-2) for all curing conditions

in Figure 5-17. Regression analyses to establish empirical relationship between compressive

strength and splitting tensile strengths were performed using the following equations:


fct = A (5-3)


S=( (5-4)
where


f = splitting tensile strength (psi)


f = compressive strength (psi)


Mix-5SS-Slag-W/C=O 33
Mix-6-S-Slag-W/C=O 36
--x- Mix-2F-Fly ash-W/C=0 33
I I --m- Mix-4F-Fly ash-W/C= 37t









A, B = coefficients

The ACI Code 318 uses Equation 5-3 for estimation of splitting tensile strength of

lightweight concrete, where the coefficient A is equal to 6.7 [ACI, 1983]. The investigation by

Carino and Lew [Carino et al, 1982] determined that the coefficient A was approximately 6.49.

They suggested that Equation 5-4 was better than Equation 5-3 in the estimation of splitting

tensile strength from compressive strength. The coefficient B was determined to be 0.73 in their

investigation.

The results of the regression analyses are summarized in Table 5-4. The coefficient A

(6.91) is slightly higher than both the values suggested by ACI (6.7) and the value by Carino and

Lew (6.49). The coefficient B (0.7185) is slightly lower than that suggested by Carino and Lew

(0.73). These two regression equations are also plotted on Figure 5-17. As can be seen from

Figure 5-17, Carino and Lew model gives a better fit to the experimental data than the ACI

model, while ACI Building Code 318-92 tends to overestimate splitting tensile strength at low

compressive strength and underestimate splitting tensile strength at high compressive strength

because the power exponent of the equation is too low.

Table 5-6 Regression analysis for relating compressive strength to splitting tensile strength
Square root of Square root of
absolute sum absolute sum
Equation Curing Coefficient Standard s o
Equation A or B Error of squares by of squares by
condition A or B Error
modified original
equation equation
ACI
= A.Moist
f =Aoit 6.91 0.76 60 62.3
st curing
A = 6.7
Carino and Lew
Moist
SMoist 0.72 0.015 45 75.7
st curing
B = 0.73












1000
Measurement
900 C arino and Lew model
-ACI code
800




400- --- ---- --- ^ ^ --
700

0)
600

0 500

400

S300

200 _

100

0
0 2000 4000 6000 8000 10000 12000 14000
Compressive Strength (psi)


Figure 5-17 Relationship between compressive strength and splitting tensile strength










5.5 Analysis of Elastic Modulus Test Results

The average elastic modulus values at various curing ages of the fourteen concrete mixes

evaluated are displayed in Table 5-7. The individual elastic modulus values are shown in Table

A-3 in Appendix A.

Table 5-7 Elastic module of the concrete mixtures evaluated (x 106 psi)
Mix W/C Fly ash Slag Age of Testing (days)
Number 3 7 14 28 56 91
Mix-1F 0.24 20% 4.74 4.93 5.23 5.40 5.54 5.58
Mix-2F 0.33 20% 3.43 3.77 4.08 4.31 4.43 4.67
Mix-3F 0.41 20% 4.40 4.85 5.05 5.14 5.28 5.70
Mix-4F 0.37 20% 4.49 4.61 4.88 5.01 5.15 5.29
Mix-5S 0.33 50% 4.11 4.66 4.88 5.09 5.23 5.23
Mix-6S 0.36 50% 4.27 4.92 5.18 5.45 5.62 5.66
Mix-7S 0.41 70% 3.90 4.30 4.52 4.60 4.73 4.76
Mix-8S 0.44 50% 3.96 4.39 4.84 5.00 5.13 5.16
Mix-9LF 0.31 20% 2.76 2.92 3.13 3.27 3.40 3.50
Mix-O1LS 0.39 60% 1.75 1.88 2.36 2.69 3.01 3.04
Mix-2GF 0.33 20% 3.80 4.22 4.61 4.96 5.06 5.19
Mix-3GF 0.41 20% 4.15 4.62 5.52 5.61 5.93 5.96
Mix-5GS 0.33 50% 3.15 3.82 4.65 5.17 5.37 5.56
Mix-7GS 0.41 70% 2.69 3.38 4.10 5.25 5.60 5.73

As can be seen from Table 5-7, for the normal weight aggregate concretes investigated in

this study, the elastic modulus of concrete varies from 4.50x106 to 6.00x106 psi. For the

lightweight aggregate concrete, the modulus of elasticity varies from 3.00x106psi to 3.70x106

psi.

As shown in Figures 5-18 through 5-21, two different normal weight coarse aggregates

give considerable influence on the elastic modulus of concrete. With other mixture components

constant in volume, the concrete mixtures with Georgia granite aggregate have higher elastic

modulus than those with Miami Oolite limestone aggregate. For example, Mix-7GS has an

elastic modulus of 5.73x106 psi at 91 days, 20.4% higher than 4.76x106 psi, which is the value of

elastic modulus of Mix-7S at 91 days. Mix-7S has a compressive strength at 91 days slightly

higher than that of Mix-7GS. Also, we can see from the comparison between Mix-2F and Mix-










2GF, Mix-3F and Mix-3GF, and Mix-5S and Mix-5GS that Mix-2F, Mix-3F and Mix-5S have a

lower elastic modulus than the corresponding Mix-2GF, Mix-3GF and Mix-5GS, respectively.

The compressive strengths of Mix-2F, Mix-3F and Mix-5S are higher than those of the

corresponding Mix-2GF, Mix-3GF and Mix-5GS, respectively, at various curing ages.

It is interesting to note that high strength but low elastic modulus concrete can be obtained

through using lightweight aggregate. For example, Mix-9LF, lightweight aggregate concrete, has

similar compressive strength and splitting tensile strength to Mix-7S, with Miami Oolite

limestone aggregate, while the elastic modulus of Mix-9LF at 91 days is only about 3.50x106 psi,

which is about 36% lower than that of Mix-7S. Thus, to achieve high strength but low elastic

modulus concrete mixture, which is desirable for concrete pavement, a lightweight aggregate

may be used.








O 4 00E +06





2.00E+06-


1.00E+06 .,,,


0.00E+00-
0 3 7 14 28
ULimestone 0 3.43E+06 3.77E+06 4.08E+06 4.31E+
OGranite 0 3.80E+06 4.22E+06 4.61E+06 4E+
Curing Age o



Figure 5-18 Effects of coarse aggregate type on modulus of elasticity of Mix-2F and Mix-2GF


































I I,'E ,'




0 ,1:'E

t Ln-.: i .:.r,
`Gr n,.i


:4 :" 1 56


i:, 4 4i:,E :,i 4 ,:,'E ,:,i ". L'E. E ii M14E U06
S a 1"SE-,: ,1 4 62E S S+ S 2E -',O 5. 61E+06
Cuir.rg Age dljaS


5 28E+


Figure 5-19 Effects of coarse aggregate type on modulus of elasticity of Mix-3F and Mix-3GF


Figure 5-20 Effects of coarse aggregate type on modulus of elasticity of Mix-5S and Mix-5GS
















4.00E +06











0 3 7 14 28 56
Limestone 0 3.90E+06 4.30E+06 4.52E+06 460E+06 473E+
OGranite 0 2.69E+06 3.38E+06 4.10E+06 525E+065
Curing Age


Figure 5-21 Effects of coarse aggregate type on modulus of elasticity of Mix-7S and Mix-7GS

5.6 Relationship between Compressive Strength and Elastic Modulus

The elastic modulus of concrete is affected by the modulus of elasticity of the aggregate

and by the volumetric proportion of aggregate in the concrete. Thus, there is no surprise that

there is no agreement on the precise form of the relationship between compressive strength and

elastic modulus.

In this study, modification was made on the expression recommended by ACI 318-89,

given as follows:


E = a (5-5)
In the equation ac is a parameter to be determined through curve-fitting regression analysis. Its

value recommended by ACI is 57000.









The regression analysis was carried out on the expression recommended by ACI 318-95,

given as follows, to fit the experimental data. In this formula, the unit weight of concrete was

also used.

E =A w15- (5-6)
Where E is elastic modulus in psi; f/ is compressive strength in psi; w is unit weight of concrete

in pcf; and A is coefficient to be determined through regression analysis. The recommended

value by ACI 318-95 is 33.0.

The compressive strengths of fourteen concrete mixtures were plotted against elastic

modules at corresponding curing ages, as shown in Figure 5-22. It indicates that coarse aggregate

type has significant effects on the elastic modulus of concrete. The results from regression

analysis were presented in Table 5-8. And the modified ACI 209 equation was plotted in Figure

5-22 together with the experimental measurements.

It can be seen that the determined values of coefficient ac for the concrete mixtures with

three different types of aggregate are fairly far away from the ACI suggested value of 57000.

Regression analysis was performed using ACI 318-95 equation, which was required to go

through the origin. The analyzed results are presented in Table 5-9. It can be seen from Table 5-

9 that the coefficient A (33.64) obtained from regression analysis is nearly identical to the

coefficient (33.0) given by ACI code. However, the errors from the regression equation which is

required to go though the origin are higher than those from that regression equation that is not

required to go through the origin, as seen from Table 5-9.

In addition, the results of regression analysis for different curing conditions using ACI

318-95 formulas are presented in Table 5-10. The elastic modulus of concrete at all curing

conditions is plotted against w15" in Figure 5-23. As can be seen from Table 5-10, curing









time appears to have a significant effect on the coefficient of the regression equations. The

regression coefficients obtained from the samples moist-cured for 28 days are higher than those

obtained from other curing times. Thus, the prediction will be conservative if the regression

coefficients are obtained from the samples moist-cured for 28 days.

For the concretes investigated in this study, the following modified ACI 318-95 equation

can be used for prediction of elastic modulus:


E=30.16-wl.5 f +484200 (5-7)


Where E is elastic modulus in psi; c is compressive strength in psi; w is unit weight of concrete
in pcf

5.7 Summary of Findings

This chapter presents the testing results from the strength tests in this study. The major

findings are given as follows:

(1) Splitting tensile strengths of the concrete mixtures using granite aggregate were
significantly lower than those using Miami Oolite limestone aggregate. This is due
probably to the poor bonding condition between hardened cement paste and granite
aggregate.

(2) Compressive strengths of concretes with granite aggregate were comparable to or lower
than those of concretes with Miami Oolite limestone aggregate.

(3) The concrete with granite aggregate had higher elastic modulus than that with Miami
Oolite limestone aggregate, while the lightweight aggregate concretes had lower elastic
modulus than the normal weight concretes.

(4) Fly ash concretes develop compressive strength and splitting tensile strength at a slower
rate than the slag concretes. Fly ash concrete shows significant strength gain after 28
days, while this was not seen from the slag concrete mixtures.

(5) The ACI 209 Equation for prediction on compressive strength ( f (t)) at various curing
age from compressive strength at 28 days (f2 (t)), which is given as follows, was
modified to give better strength prediction for the various mixtures.









Table 5-8 Results of regression analysis for prediction of elastic modulus using the equation
recommended by ACI 318-89

Results A t granite lightweight Limestone
a (Best-fit values) 62721 43777 55949
Standard Error of ca 870.6 692.3 309.1
95% confidence intervals for
a 60920 to 64523 42253 to 45301 55327 to 56572
Degrees of Freedom 23 11 47
R2 0.8712 0.922 0.8758
Absolute Sum of Squares 2.478E+12 2.693E+11 1.619E+12
Sy.x 328220 156461 185594
Number of points Analyzed 24 12 48


Table 5-9 Results of regression analysis for prediction of elastic modulus using ACI 318-95
equation
With equation going through the Without forcing the equation to go
Best-fit values origin through the origin
Slope 33.64 0.2671 30.18 1.169
Y-intercept when X=0.0 0.0000 484200 + 159900
X-intercept when Y=0.0 0.0000 -16040
I/slope 0.02973 0.03313
95% Confidence Intervals
Slope 33.10 to 34.17 27.85 to 32.51
Sy.x 335100 319700












8.00E+06 -_
o Georgia granite
7.00E+06 Stalite lightweight
A Miami Oolite limestone

6.00E+06 j A"


5.00E+06 A--
:0 A A
A&
S4.00E+06

-/ ,
5 3.00E+06 -
0

2.00E+06 '--


1.00E+06 /--


0.00E+00
0 2000 4000 6000 8000 10000 12000 14000
Compressive Strength (psi)


Figure 5-22 Relationship between compressive strength and elastic modulus based on ACI Code


7.00E+06


6.00E+06 -


5.00E+06


4.00E+06
0 *
S*
3.00E+06 -
0
2.00E+06


1.00E+06


0.OOE+00 -
0 40000 80000 120000 160000 200000
W15f 05



Figure 5-23 Plot of elastic modulus against w15"* for all curing conditions


124











Table 5-10 Results of regression analysis for prediction of elastic modulus using the ACI 318-95 equation for different curing
conditions

Overall 3-day 7-day 14-day 28-day 56-day 91-day

Slope 30.18 + 1.169 26.24 + 3.857 27.76 + 3.763 29.17 + 3.123 30.00 + 2.217 28.78 2.965 29.38 + 2.771
484200+ 800000+ 644500+ 614000+ 581900+ 779700+ 704200+
Y-intercept when X=0.0 159900 437100 478400 424400 315800 438000 418700
X-intercept when Y=0.0 -16040 -30490 -23220 -21050 -19400 -27090 -23970
I/slope 0.03313 0.03811 0.03602 0.03428 0.03334 0.03475 0.03404
95% Confidence Intervals
27.85 to 17.84 to 19.56 to 22.37 to 25.16 to 22.32 to 23.34 to
Slope 32.51 34.64 35.96 35.98 34.83 35.24 35.41
165500 to -152400 to -397900 to -310800 to -106200 to -174800 to -208100 to
Y-intercept when X=0.0 802900 1752000 1687000 1539000 1270000 1734000 1616000
-28780 to -97520 to -85720 to -68530 to -50350 to -77450 to -69070 to
X-intercept when Y=0.0 5098 4433 11130 8673 3056 4974 5892
Goodness of Fit
r2 0.8906 0.7941 0.8194 0.8791 0.9385 0.887 0.9035
Sy.x 319700 394800 386700 310500 216700 292900 275100
Is slope significantly non-zero?
F 667.2 46.29 54.43 87.25 183.1 94.22 112.4
DFn, DFd 1.000, 82.00 1.000, 12.00 1.000, 12.00 1.000, 12.00 1.000, 12.00 1.000, 12.00 1.000, 12.00
P value < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001
Deviation from zero? Significant Significant Significant Significant Significant Significant Significant
Data
Number of X values 84 14 14 14 14 14 14
Maximum number of Y
replicates 1 1 1 1 1 1 1
Total number of values 84 14 14 14 14 14 14









I t
fc (t) = fc28
fc() 4.0+0.85,t c28

The modified equation has the following form for the concrete with different coarse
aggregates:


fc(= a .t c28

The value of a was found to vary from 1.1 to 2.6 for the concretes with Miami Oolite
limestone aggregate, from 2.6 to 5.3 for the concretes with Georgia granite aggregate,
and from 4.2 to 6.7 for lightweight aggregate concretes; the value of 3 was found to vary
from 0.82 to 0.93 for the concretes with Miami Oolite limestone aggregate, from 0.82 to
0.89 for the concrete with Georgia granite aggregate, and from 0.74 to 0.82 for
lightweight aggregate concrete in this study.

(6) The relationship between compressive strength ( f) and splitting tensile strength ( f,) is
established for the concrete mixtures investigated in this study. The Carino and Lew
model, given as follows,
S)0.73

was modified to the following equation:

t = 0.7185
fct c
Where f, and fc, are in units of psi.

(7) The relationship between compressive strength and modulus of elasticity was refined in
this study using Least Square of Curve-fitting Technique. The ACI 318-89 Equation,
which is
Ec = 57000Ff
was modified to the following equation:


Where a is equal to 55,949 for Miami Oolite limestone aggregate; 62,721 for Georgia
granite aggregate; and 43,777 for Stalite lightweight aggregate. f, and Ec are in units of
psi.

(8) For all three aggregate types investigated in this study, a modified ACI 318-95 prediction
equation was developed:
E = 30.16 w1 f + 484200
Where w is the density of concrete in pound per cubit foot. fc and Ec are in units of psi.









CHAPTER 6
ANALYSIS OF SHRINKAGE TEST RESULTS

6.1 Introduction

This chapter presents the results from shrinkage tests on the concrete mixes evaluated in

this study. The effects of various factors on shrinkage behavior of concrete were discussed.

Regression analysis was performed to establish the relationship between compressive strength at

the age when shrinkage test was started and shrinkage strain at 91 days, and the relationship

between elastic modulus and shrinkage of concrete. Empirical equations relating compressive

strength and elastic modulus to shrinkage of concrete are given. Also, the evaluation was made

on ACI 209 model and C.E.B-F.I.P model for their effectiveness in shrinkage prediction. At last,

ultimate shrinkage strain of the concretes investigated in this study was approximated using an

asymptotic equation with three unknown parameters to fit experimental data.

6.2 Results and Analysis of Shrinkage Tests

Table 6-1 presents the measured shrinkage strains at the ages up to 91 days for the fourteen

concrete mixes evaluated in this study. For Mix-IF through Mix-O1LS, one group of concrete

specimens was moist-cured for 7 days and then air-dried in the laboratory for the rest of the time;

another group of specimens were moist-cured for 14 days and then air-dried for the rest of the

time, while, for Mix-2FG through Mix-7SG, only one curing condition, i.e. 14-day moist curing

and then air-dried for the rest of time, was evaluated.

6.2.1 Effects of Curing Conditions on Shrinkage Behavior of Concrete

As can be seen from Table 6-1 as well as Figure 6-1, curing condition has substantial

effects on shrinkage behavior of concrete mixtures. For the concrete mixtures with fly ash, the

specimens moist-cured for 14 days have appreciable lower shrinkage strains than those moist

cured for 7 days. For example, the shrinkage strain of Mix-IF moist-cured for 14 days is











Table 6-1 Shrinkage strains of the concrete mixtures evaluated at various curing ages
Age of testing (days)
No. of Mix Curing condition Predicted ultimate
3 7 1 2 5 shrinkage strain


Mix-IF 7-day moist cure
Mix- 1F
14-day moist cure
Mix-2F 7-day moist cure
Mix-2F-- -- --
14-day moist cure
Mix-3F 7-day moist cure
14-day moist cure
7-day moist cure


14-day moist cure
7-day moist cure
14-day moist cure
7-day moist cure


14-day moist cure
Mix-7S 7-day moist cure
Mix-7S
14-day moist cure
Mix-8S 7-day moist cure
14-day moist cure
,. 7-day moist cure


1vh1x-LJLr

Mix-lOLS

T%.Aivu9 (TF


14-day moist cure
7-day moist cure
14-day moist cure
7-day moist cure


14-day moist cure
Mix-3GF 7-day moist cure
Mix-3GF
14-day moist cure
Mix-5GF 7-day moist cure
Mix-5GF
14-day moist cure
7-day moist cure


VI1X- / Tr


0.20E-04
0.14E-04
0.51E-04
0.31E-04
0.40E-04
0.24E-04
0.37E-04
0.31E-04
0.44E-04
0.43E-04
0.42E-04
0.33E-04
0.39E-04
0.38E-04
0.73E-04
0.50E-04
0.49E-04
0.46E-04
0.67E-04
0.38E-04

0.32E-04

0.29E-04

0.39E-04

0.43E-04


0.44E-04
0.35E-04
0.97E-04
0.69E-04
0.73E-04
0.50E-04
0.71E-04
0.53E-04
0.88E-04
0.74E-04
0.84E-04
0.71E-04
0.81E-04
0.73E-04
1.23E-04
0.98E-04
0.96E-04
0.83E-04
1.30E-04
0.90E-04

0.61E-04


0.75E-04
0.61E-04
1.54E-04
1.12E-04
1.24E-04
0.87E-04
1.18E-04
0.92E-04
1.30E-04
1.10E-04
1.23E-04
1.12E-04
1.26E-04
1.11E-04
1.61E-04
1.36E-04
1.34E-04
1.34E-04
1.98E-04
1.52E-04

1.09E-04


0.54E-04 0.84E-04


0.64E-04


1.04E-04


1.18E-04
1.00E-04
2.10E-04
1.73E-04
1.77E-04
1.37E-04
1.76E-04
1.42E-04
1.70E-04
1.49E-04
1.56E-04
1.41E-04
1.70E-04
1.48E-04
1.94E-04
1.69E-04
2.25E-04
1.84E-04
2.60E-04
2.09E-04

1.61E-04

1.23E-04

1.40E-04


1.63E-04
1.36E-04
2.61E-04
2.33E-04
2.21E-04
1.84E-04
2.33E-04
1.97E-04
2.01E-04
1.78E-04
1.83E-04
1.64E-04
2.02E-04
1.84E-04
2.28E-04
2.02E-04
2.87E-04
2.41E-04
3.20E-04
2.80E-04

2.04E-04

1.57E-04

1.68E-04


2.02E-04
1.67E-04
2.86E-04
2.58E-04
2.48E-04
2.16E-04
2.67E-04
2.31E-04
2.16E-04
1.93E-04
1.95E-04
1.76E-04
2.23E-04
2.04E-04
2.50E-04
2.30E-04
3.22E-04
2.76E-04
3.58E-04
3.17E-04

2.31E-04

1.82E-04

1.84E-04


2.66E-04
2.27E-04
3.39E-04
3.20E-04
3.03E-04
2.85E-04
3.64E-04
3.44E-04
2.46E-04
2.29E-04
2.16E-04
1.93E-04
2.55E-04
2.40E-04
2.43E-04
2.20E-04
3.95E-04
3.49E-04
4.22E-04
3.96E-04


2.83E-04

2.62E-04

2.18E-04


0.74E-04 1.00E-04 1.31E-04 1.63E-04


IVllx-4r

Mix-5S

UlYi-v;S


14-day moist cure


1.81E-04 2.19E-04









0.000167 at 91 days, which is 23.2% less than that of the same mix moist-cured for 7 days. The

shrinkage strain at 91 days is 0.000258 for Mix-2F moist-cured for 14 days, which is 10.9% less

than that of the same mix moist-cured for 7 days. Also, the shrinkage strain of Mix-3F moist-

cured for 14 days is 0.000216, which is 14.8% less than that of the same mix moist-cured for 7

days. Substantial decrease in shrinkage strain also can be seen from Mix-4F. Shrinkage strain of

7-day moist-cured specimens is 13.5% higher than that of 14-day moist-cured specimens for

Mix-4F.

For the concrete mixtures with slag, the effects of curing condition on shrinkage strain are

significant as well. For instance, the shrinkage strain ofMix-5S moist-cured for 14 days is 11.9%

less than that of the same mix moist-cured for 7 days. Also, for Mix-6S, Mix-7S and Mix-8S, the

shrinkage strains of the specimens moist-cured for 14 days are at least 10% less than those of the

same mixtures moist-cured for 7 days.

In addition, curing condition has similar effects on shrinkage strain of lightweight

aggregate concretes as that on normal weight aggregate concrete. The shrinkage strains of Mix-

9FL and Mix-1OSL moist-cured for 14 days are 16.5% and 11.6%, respectively, less than those

of the same mixtures moist-cured for 7 days.

6.2.2 Effects of Mineral Additives on Shrinkage Behavior

As can be seen from Table 6-1 as well as Figure 6-1, the results from 14 mixtures indicate

that the concrete mixtures with fly ash have higher shrinkage strains than those with slag. For

example, Mix-3F has the same water to cementitious materials ratio as Mix-7S, while the

shrinkage strain of Mix-3F moist-cured for 7 days is 0.000248, which is more than 10% higher

than that of Mix-7S moist-cured for 7 days even though the water content of Mix-3F (254 lbs per

cubit yard) is less than that of Mix-7S (267 lbs per cubit yard). For another example, Mix-2F and


129











4.00E-04
07- day moist curing
S14-day moist curing
3.50E-04

3.00E-04

5 2.50E-04

2 2.00E-04









1F 2F 3F 4F 5S 6S 7S 8S 9LF 10LS
Mixture


Figure 6-1 Effects of curing condition on shrinkage strain of concrete mixtures at 91 days

Mix-5S have identical water to cementitious ratio, while the shrinkage strain of Mix-2F moist-

cured for 7 days is 0.000286 at 91 days, or 24.5% higher than that of Mix-5S moist-cured for 7

days.

As also can be seen from the concrete mixtures with Georgia granite aggregate, Mix-2FG

and Mix-3FG have higher shrinkage strains as compared with the corresponding Mix-5SG and

Mix-7SG, respectively, even though Mix-2GF has identical water to cementitious materials ratio

as Mix-5SG, and Mix-3GF has the same water to cementitious material ratio as Mix-7GS.

6.2.3 Effects of Water Content on Shrinkage Behavior

Water content per unit volumetric concrete is an important factor influencing the

magnitude of shrinkage strain since drying shrinkage is caused by the moisture movement from

the concrete. Generally, the higher the water content, the more the free water inside concrete is

available because water can not be consumed rapidly and completely. Thus, shrinkage strain of

concrete is increased with an increase of free water content. As can be seen from Figure 6-2, the


130











shrinkage strains at 91 days increase with the increase of water content for the normal-weight

concrete mixtures evaluated in this study.


3.50E-04 -1
0 Miami Oolite limestone
3.OOE-04 Georgia granite
3.00E-04 -----


S2.50E-04


" 2.00E-04


a 1.50E-04


u 1.00E-04


5.00E-05


0.00E+00 I I
220 230 240 250 260 270 280 290
Water Content (Ibs/yard3)


Figure 6-2 Effects of water content on shrinkage strain at 91 days

Figure 6-3 shows a plot of water to cementitious materials ratio versus shrinkage strain of

concrete at 91 days. No clear trend can be observed to relate water to cementitious materials ratio

to the magnitude of shrinkage strain of concrete.

The significant role played by water content also extends to the lightweight aggregate

concretes, Mix-9FL and Mix-1OSL. As can be seen from Table 6-1, the water content of Mix-

10SL is 275 lbs per cubit yard, higher than 235 lbs for Mix-9FL. The shrinkage strain at 91 days

for Mix-10SL is much higher than that of Mix-9FL.

6.2.4 Effects of Aggregate Types on Shrinkage Behavior

In this study, two types of normal weight coarse aggregate, Miami Oolite limestone


aggregate and Georgia granite aggregate were investigated for their effects on shrinkage


0

0 o

0 0











behavior of four concrete mixtures. The experimental data from the specimens moist-cured for


14 days indicate that the concrete mixtures using Georgia granite aggregate developed


significantly less shrinkage strain at 91 days than those with Miami Oolite limestone aggregate.


For example, as can be seen from Figure 6-4, Mix-2FG, which has the same mix proportion as


Mix-2F other than the coarse aggregate replaced by Georgia granite aggregate, has a shrinkage


strain of 0.000231, which is 23.8% lower than that of Mix-2F using Miami Oolite limestone as


coarse aggregate.


2.80E-04

2.60E-04

2.40E-04

2.20E-04

2.00E-04

1.80E-04

1.60E-04

1.40E-04

1.20E-04

1.00E-04


0.20 0.25 0.30 0.35 0.40 0.45 0.50
Water to Cementitious Materials Ratio


Figure 6-3 Plot of water to cementitious materials ratio versus shrinkage strain at 91 days

The same situation can be seen from the comparison between Mix-3F and Mix-3FG, Mix-


5S and Mix-5SG, and Mix-7S and Mix-7SG. The shrinkage strain of Mix-3FG is 0.000182 at 91


days, which is 18.7% less than that of Mix-3F, which has shrinkage strain of 0.000216.


Shrinkage strains of Mix-5S and Mix-7S at 91 days are also 10% higher than those of Mix-5SG


and Mix-7SG.


o Miami Oolite limestone
o 0.33 Georgia Granite


S0.33 o 0.41
o 0.37
00.33 o 00.37 W ---
o C.44
o 0.33 o 0.41
0.33 ___ 41 o C.44
o 0.36
o C.24 o0.33o 0.36
0-C.24










For lightweight aggregate concretes, such as Mix-9LF and Mix-1OLS, their shrinkage

strains are significantly higher than the concrete mixtures using normal weight aggregate.


3.00E-04
SMiami Oolite limestone
BGeorgla granite
2.50E-04 --


2.00E-04


e 1.50E-04... --.

S1.00E-04...... ...


5.00E-05


0.00E+00
Mix-2 Mix-3 Mix-5 Mix-7
Mixture

Figure 6-4 Effects of coarse aggregate type on shrinkage behavior of concrete

6.2.5 Relationship between Compressive Strength and Shrinkage Strain

Over the past decades, the study on shrinkage behavior of concrete has been carried out

extensively. The effects of various factors, such as water to cement ratio, aggregate type,

aggregate content, mineral additives, and cement content so on, on shrinkage behavior have been

studied. However, since concrete is a complicated composite material, the effects of various

components and their proportions on shrinkage behavior are intertwisted together. Also, because

of massive introduction of chemical admixtures to concrete, such as air entraining agent and

water reducer, shrinkage behavior of concrete becomes more complex. Thus, shrinkage behavior

of concrete can not be reasonably estimated based on the simple addition of every individual

factor's function. Therefore, it is desirable to relate the shrinkage behavior of concrete to one or

more fundamental properties of concrete, for example, compressive strength, tensile strength or

elastic modulus at a particular age. In doing so, it assumes that the fundamental properties of









concrete are closely related to one another, i.e. one fundamental property can be predicted from

another. In doing so, a complicated fundamental property can be estimated by a simple

fundamental property without complicated and time-consuming experimental test involved.

In trying to find out the relationship between compressive strength and shrinkage behavior

of concrete, compressive strength at the age when shrinkage test was started was plotted against

shrinkage strain at 91 days in Figure 6-5.

As shown in Figure 6-5, it appears that there exists a very interesting relationship between

the shrinkage strains at 91 days and compressive strength regardless of which type of coarse

aggregate was used for concrete. Then, regression analysis was carried out using an exponential

function with two unknown parameters, given as Equation 6-1. The regression analysis results

are presented in Table 6-2.


esh -= -e (6-1)

In this formula, f, is compressive strength of concrete at the age of initial shrinkage test.

As can be seen from Table 6-2, best fit value ofc is 5.113x10-4; best fit value of 3 is

1.127x10-4; and correlation coefficient, R2, is 0.8226. The above equation with parameters

obtained from regression analysis was plotted in Figure 6-5 as solid line. It indicated that

shrinkage strain at 91 days can be well estimated by the compressive strength of concrete at the

age of when shrinkage test was started. Furthermore, this relationship is not affected by such

factors as aggregate type and curing age.

Therefore, even though exponential equation from regression analysis may not be a

fundamental relationship between compressive strength and shrinkage of concrete, it may be

very convenient way practically to have an accurate enough estimation on shrinkage strain just

based on the compressive strength without time-consuming shrinkage test involved.


134










Table 6-2 Results of regression analysis on relationship of compressive strength to shrinkage
strain
Absolute Sum of
Regression Best-fit Standard Error 95% Confidence 2 Sque Rot du
Results Value (SE) Interval to Error (ootS
to Error (SSE)
4.706E-04-
a 5.113E-04 2.042E-05
5.521E-04
5.521E-00.8226 2.131E-05
1.014E-04-
3 1.127E-04 5.654E-06 1.01
1.239E-04



5.00E-04 -
o Miami Oolite limestone
4.50E-04 0 Lightweight aggregate
A Georgia granite
4.00E-04

( 3.50E-04
Q
0 3.00E-04 -
r u o
2 2.50E-04 o

0 2.00E-04 -- o__o

1.50E-04
0
1.00E-04

5.00E-05

0.00E+00
0 2000 4000 6000 8000 10000 12000 14000
Compressive Strength at the Age of Initial Shrinkage Test (psi)


Figure 6-5 Relationship between compressive strength and shrinkage strain at 91 days

6.2.6 Relationship between Elastic Modulus and Shrinkage Strain

Since close relationship has been found between compressive strength and shrinkage of

concrete, and since there is direct relationship between compressive strength and elastic

modulus, elastic modulus and shrinkage should be related to each other as well.

As shown in Figure 6-6, shrinkage strains at 91 days for all the concretes investigated in

this study, including normal weight aggregate concrete and lightweight aggregate concrete, were

plotted against elastic modulus at the age of shrinkage test starts. There is no surprise that similar










relationship to compressive strength and shrinkage can be found between elastic modulus and

shrinkage. Regression analysis was performed using an exponential function with two unknown

parameters, as given in Equation 6-2, and the analyzed results are presented in Table 6-3.

-P.E,
Esh =- Ec (6-2)


In this equation, Ec is elastic modulus of concrete at the age when shrinkage test was

started.

Table 6-3 Results of regression analysis on relationship of elastic modulus to shrinkage strain
Regression Best-fit Standard Error 95% Confidence 2 (S
Results Value (SE) Interval )
5.911E-04-
U 6.595E-04 3.429E-05E-04
7.279E-04
0.8152 2.175E-05
2.045E-04-
3 2.270E-07 1.129E-08 2 E-4
2.495E-04



5.00E-04

o Miami Oolite limestone
Lightweight aggregate
4.00E-04 A Georgia granite
a) 0


3.00E-04
S* o






1.00E-04
2.00E-04
1.00 E -04 ------------



0.OOE+00
0.00E+00 2.00E+06 4.00E+06 6.00E+06 8.00E+06
Modulus of Elasticity (psi)


Figure 6-6 Relationship between shrinkage strain at 91 days and modulus of elasticity








6.3 Evaluation on Shrinkage Prediction Models

In this study, the ACI 209 model and C.E.B-F.I.P model were evaluated on their

effectiveness and accuracy in prediction of shrinkage behavior of typical concretes used in

Florida.

6.3.1 ACI-209 model

The concrete shrinkage prediction model recommended by ACI-209 (1992) is given as

follows:

( ) (6-3)
v sh t 35 +t (- sh u
Where (esh ) time dependent shrinkage strain; (esh ) ultimate shrinkage strain; and t -

time variable in days

If there is no available shrinkage data from the specific concrete mixture, the ultimate

shrinkage strain, (sh ) can be assumed to be the following:

(Esh ) = 780 x 10-6 x h (6-4)
Where Ysh a product of all the applicable correction factors for the testing conditions other

than the standard condition; Ysh = 1 under standard testing condition.

Ysh is obtained by multiplying the ultimate shrinkage strain under the standard condition by

the appropriate correction factors, such as correction factors for the effect of initial moist curing,

correction factor for the effect of ambient relative humidity, correction factor for the effects of

specimen size, correction factor for concrete composition and so on. In this study, Ysh is

calculated as follows:

7sh = 71a 7rh 7s 7a *at *p (6-5)
The correction factors applicable to the concrete mixes evaluated in this study are shown in

Table 6-4.









Table 6-4 Correction factors for the ACI 209 model on shrinkage prediction


No. of Mix

Mix-IF
Mix-2F
Mix-3F
Mix-4F
Mix-5S
Mix-6S
Mix-7S
Mix-8S
Mix-9LF
Mix-10LS
Mix-2GF
Mix-3GF
Mix-5GS
Mix-7GS


Yla
7-day
moist
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916


14-day
moist
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814


Ysh
Yrh Ys Ya Yat Yp 7-day
moist
0.77 0.85 0.57 1.00 0.88 0.30
0.77 0.83 0.87 1.00 0.88 0.45
0.77 0.83 0.69 1.00 0.88 0.36
0.77 0.83 0.64 1.00 0.88 0.33
0.77 0.84 0.80 1.00 0.88 0.42
0.77 0.83 0.66 1.00 0.88 0.34
0.77 0.84 0.96 1.00 0.88 0.50
0.77 0.83 0.80 1.00 0.88 0.41
0.77 0.83 0.73 1.00 0.88 0.38
0.77 0.83 0.93 1.00 0.88 0.48
0.77 0.83 1.13 1.00 0.88 0.58
0.77 0.83 0.60 1.00 0.88 0.31
0.77 0.84 0.96 1.00 0.88 0.50
0.77 0.83 0.80 1.00 0.88 0.41


6.3.2 CEB-FIP Model


In this model, the effects of cement type, ambient relative humidity, compressive strength

of concrete, and size effect of specimen on shrinkage strain of concrete are taken into

consideration. The total shrinkage strain may be estimated by the following equation:

E t,' t )= E t t) (6-6)
cs \ s / cs0 s J s )
Where Es(t, t ) = time dependent total shrinkage strain; Ec, = notational shrinkage

coefficient; and f, (t ts) = coefficient to describe the development of shrinkage with time.


E S can be estimated by the following equation:


(6-7)


Ecs = 160 +10,8s 9 ] x 10-6 X/JRH


where /l, a coefficient depending on the type of cement is equal to 5 for normal or rapid

hardening cements; fm = the mean compressive strength of concrete at the age of initial

shrinkage tests. f,,o is a constant, equal to 10MPa. /RH can be computed as follows:


14-day
moist
0.27
0.40
0.32
0.29
0.37
0.30
0.44
0.37
0.33
0.43
0.52
0.27
0.44
0.37









f ^3
RH = -1.55 1 -RH for 40% < RH < 99% (6-8)
R RH0

With RH equal to 75% in this study and RHO equal to 100%, then,


csO = 160+10Pf,, 9 x10-6 x 0.8959 (6-9)

p, (t t) can be estimated by the following equation:


S (tts) 0.5


8s t ) t) tl2 (6-10)
h t-t
WA t
\ \ 0} Il

Where h = 2Ac = the notational size of member (in mm), where A, is the cross-sectional
u

area (mm2) and u is the perimeter (mm) of the member circular cross section (27r) in contact

with the atmosphere. H is equal to 1.5 for 6xl2in cylinder. h0 is equal to 100 mm. t1 is equal to

1 day.

Therefore, the above equation can be simplified as follows:


P (t) = t (6-11)
s() 203.23 + t

The shrinkage strains at 91 days for all the concrete mixtures investigated in this study

were compared with the calculated results using ACI 209 model and C.E.B-F.I.P model in Figure

6-7. The hollow circle indicates the prediction by C.E.B-F.I.P model, and solid black dot

represents the prediction by ACI 209 model. As shown in Figure 6-7, C.E.B-F.I.P model gives

encouraging prediction in comparison with the experimental data, while ACI-209 model

provides extreme over-estimation.


139










5.00E-04


- 4.00E-04 __
E
'y= x
S3.00E-04



0 2.00E-04 o -


1.00E-04 *


0.OOE+00
0.00E+00 1.00E-04 2.00E-04 3.00E-04 4.00E-04 5.00E-04
Predicted Shrinkage Strain


Figure 6-7 Comparison between the shrinkage strain at 91 days and the shrinkage strain
calculated by ACI 209 model and C.E.B-F.I.P model

6.4 Prediction of Ultimate Shrinkage Strain

Shrinkage of concrete lasts for a long time with decreasing shrinkage rate. Generally, it is

assumed that concrete will shrink with time to a limiting value, called ultimate shrinkage strain,

which is a very important parameter in concrete structural design. In this study, an asymptotic

equation, given as follows, was used to fit the experimental data.



sh )= a ./ (6-12)

As can be seen from the above equation, shrinkage strain will approach its limiting value 3

as time goes to infinite value. Thus, 3 is the ultimate shrinkage strain.

Curve-fitting regression analysis was performed using Least Square Method, which is

detailed as follows:


140









6.4.1 Least Square Method of Curve-fitting

The method of least squares was used when fitting data. The model selected to relate the

response data to the predictor data with two coefficients is given as follows:


,= .,6 (6-13)
x+
Where

a P and y are two constitutive parameters to be determined from curve fitting process;

x is time variable, and

y is response variable, and it is the creep strain in this study.

The goal of the fitting process is to estimate the "true" but unknown coefficients of the

model. To obtain the coefficient estimates, the residual for the ith data point, r. defined as the


difference between the observed response value y. and the fitted response value jK and


identified as the error associated with the data is computed by

r=y-y (6-14)
Then, the summed square of residuals is given by

Sn 2 n \ (6-15)

Where

nl is the number of data points included in the fit, and

S is the sum of squares error estimate. The least squares method minimizes the summed

square of residuals, and then the optimized coefficients will be achieved.

Since the model used to fit the data is the ratio of two polynomials, it is a nonlinear

equation. Therefore Nonlinear Least Squares Method was used to do curve-fitting analysis in this

study.

In matrix form, nonlinear models are given by the formula









y = f(X,p)+ E (6-16)
Where

y is an n-by-1 vector of responses,

f is a function of 3 and X,

p is a m-by-1 vector of coefficients,

x is the n-by-m design matrix for the model, and

E is an n-by-1 vector of errors.

Unlike linear models, the coefficients are estimated using simple matrix techniques; an

iterative approach is used to estimate coefficients of nonlinear model. The fitted response value

is given by

y = f(X,b) (6-17)

and involves the calculation of the Jacobian of f(X,b), which is defined as a matrix of partial

derivatives taken with respect to the coefficients. Then, the coefficients are adjusted and

determination was made as to whether the fit improves. The direction and magnitude of the

adjustment depend on the fitting algorithm. In this study, Trust-region algorithm was used

because it can solve difficult nonlinear problems more efficiently than the other algorithms, and

it represents an improvement over the popular Levenberg-Marquardt algorithm.

Because nonlinear models can be particularly sensitive to the starting points, the initial

values of the estimates should be carefully defined to guarantee the convergence of regression

analysis.

6.4.2 Evaluation Methods on the Goodness of Fit

In this study, after fitting data with the model, the goodness of fit was evaluated by

graphical illustration, such as a visual examination of the fitted curve and residual plot, and









numerical measures, such as goodness of fit statistics confidence, standard error, and regression

correlation coefficient (R2).

In doing so, graphical illustration allows us to view the entire data set at once, and they can

easily display a wide range of relationships between the model and the data. The numerical

measures are more narrowly focused on a particular aspect of the data and often try to compress

that information into a single number.

In the following content, the methods used to evaluate the goodness of fit in this study are

described briefly.

* The sum of squares due to error (SSE)

This statistic, also called the summed square of residuals, measures the total deviation of

the response values from the fit to the response values. It is usually labeled as SSE.

S nS ( i (6-18)
SSE = Z w i y y i
i= 1
A value closer to 0 indicates a better fit.

* R-square

R-square, also called the square of the multiple correlation coefficient and the coefficient

of multiple determination, is the square of the correlation between the response values and the

predicted response values. It measures how successful the fit is in explaining the variation of the

data.

R-square is defined as the ratio of the sum of squares of the regression (labeled as SSR)

and the total sum of squares (labeled as SST), also called the sum of squares about the mean.

SSR is defined as


SSR = w- ( y)2 (6-19)
And SST is defined as
And SST is defined as










SST = SSR + SSE = w w (y, y)2 (6-20)
1i1
Then, according to the definition, R-square is expressed as

2SSR SST- SSE SSE
R =---- = = 1- (6-21)
SST SST SST
R-square can take on any value between 0 and 1, with a value closer to 1 indicating a better

fit.

* Root mean squared error (RMSE)

RMSE is also known as the fit standard error and the standard error of the regression

RMSE = s = MSE (6-22)
Where MSE is the mean square error or the residual mean square

SSE
MSE = SSE (6-23)
v
A RMSE value closer to 0 indicates a better fit.

* Confidence and Prediction Bounds

Confidence and prediction bounds define the lower and upper values of the associated

interval, and define the width of the interval, which indicates how uncertain we are about the

fitted coefficients, the predicted observation, or the predicted fit.

Confidence bounds were obtained through regression analysis for the fitted coefficients,

and prediction bounds for the fitted function. In this study, the confidence bounds are given

numerically, while the prediction bounds are displayed graphically.

In this study, the bounds are defined with a certainty of 95%.

In this study, the regression analysis was carried out using statistic analysis software,

GraphPad Prism, programmed by GraphPad Prism software Inc.


144











6.4.3 Predicted Results

The results of regression analysis using Equation 6-12 are presented in Table 6-5. The


ultimate shrinkage strains predicted for 14 concrete mixtures, which are represented the values

for p, are summarized in Table 6-5. Graphically, predicted ultimate shrinkage strain based on

experimental data was compared with the predictions made by original ACI-209 model and

C.E.B-F.I.P model in Figure 6-8. As can be seen from the graphical plots as well as Table-6-5,


the predicted ultimate shrinkage strains,3, for fourteen concrete mixtures vary from 0.0002 to


0.00041, which is considerable less than the predicted values by ACI 209 model and C.E.B-F.I.P

model.


6.00E-04

0-
S5.00E-04
i


0 4.00E-04


6 3.00E-04


' 2.00E-04
U)

E
S1.00E-04

E+00
O.OOE+00


0.OOE+0(


) 2.00E-04 4.00E-04
Calculated by C.E.B-F.I.P model and ACI model


3.00E-04


Figure 6-8 Comparison among the ultimate shrinkage strains from curve-fitting, CEB-FIP model
and ACI 209 model

As shown in Table 6-5, a has a value close to 1 for all concrete mixtures, while y-value is


significantly different between fly ash concrete and slag concrete. a has an average value of


* ACI 209 model
OC.E.B-F.I.P model





O *




/o o
0 03

o/ oo o o
------7 ----- ------










1.04, and y has an average value of 30.0. As can be seen from Table 6-5, y-value for the

specimens moist-cured for 7 days is higher than that for the specimens moist-cured for 14 days.

This is due probably to the fact that the evaporation rate of free water concrete becomes slower

at a longer curing age when the concrete is denser.

At last, based on the 14 concrete mixtures investigated in this study, the ultimate shrinkage

strain predicted through curve-fitting the three-parameter model to experimental data is less than

3.5x10-4 for normal-weight aggregate concrete, and 4.5x10-4 for lightweight aggregate concrete.



Table 6-5 Results of regression analysis for prediction of shrinkage strain using Equation 6-12
Mix a SE p SE Y SE R2 SSE
1F 0.983 0.024 2.66E-04 2.70E-06 31.18 1.804 0.9997 1.20x10-6
1.122 0.049 2.27E-04 4.31E-06 31.10 3.117 0.9992 1.67x10-6
2F 1.027 0.021 3.39E-04 1.51E-06 16.48 0.649 0.9998 1.27x10-6
1.137 0.042 3.21E-04 3.35E-06 19.13 1.515 0.9994 1.23x10-6
3F 1.011 0.022 3.03E-04 1.69E-06 20.05 0.869 0.9998 1.19x10-6
0.920 0.031 2.85E-04 3.89E-06 31.74 2.545 0.9994 1.81x10-6
4F 0.867 0.013 3.44E-04 2.74E-06 27.84 1.530 0.9999 1.10x10-6
0.855 0.032 3.24E-04 8.93E-06 32.44 3.910 0.9990 2.45x10-6
5S 0.996 0.045 2.46E-04 1.83E-06 12.52 1.005 0.9992 2.02x10-6
0.812 0.026 2.29E-04 1.86E-06 20.88 1.427 0.9994 1.50x10-6
6S 1.227 0.041 2.16E-04 0.86E-06 8.172 0.432 0.9997 1.16x10-6
1.332 0.125 1.93E-04 1.54E-06 6.511 0.761 0.9985 2.20x10-6
7S 1.196 0.028 2.55E-04 0.93E-06 11.37 0.449 0.9998 0.98x10-6
0.910 0.034 2.40E-04 2.13E-06 18.89 1.429 0.9993 1.74x10-6
8S 1.325 0.087 2.43E-04 1.82E-06 7.822 0.789 0.9989 2.42x10-6
1.232 0.089 2.20E-04 2.52E-06 11.61 1.406 0.9984 2.56x10-6
9LF 0.836 0.030 3.95E-04 3.09E-06 20.53 1.220 0.9996 2.11x10-6
1.018 0.030 3.49E-04 4.89E-06 31.49 2.756 0.9992 2.51x10-6
10LS 1.055 0.026 4.22E-04 3.30E-06 21.74 1.349 0.9983 4.42x10-6
0.851 0.066 3.96E-04 7.12E-06 21.04 2.796 0.9995 2.05x10-6
2GF 1.105 0.053 2.83E-04 3.39E-06 18.09 1.632 0.9994 2.16x10-6
3GF 0.832 0.052 2.62E-04 3.16E-06 48.32 2.263 0.9999 5.93x10-6
5GS 0.897 0.010 2.18E-04 1.96E-06 18.44 1.661 0.9988 2.35x10-6
7GS 0.668 0.045 2.19E-04 5.61E-06 31.11 5.619 0.9976 3.17x10-6

6.5 Summary of Findings

This chapter presents the results of shrinkage tests on the concrete mixtures investigated in

this study. The summary of this chapter and major findings are provided as follows:









(1) Fly ash concrete mixtures had slightly higher shrinkage strain at 91 days than slag
concretes. This is due probably to the slow hydration rate of fly ash in comparison with
that of slag. As a result of slower rate of hydration, there is more free water evaporating
from the interior concrete out, which can cause concrete to shrink more. Thus, it is
recommended that using a longer wet curing time would be helpful to reduce shrinkage
of fly ash concrete.

(2) Water content has a significant effect on drying shrinkage strain of concrete. The higher
the water content, the more the concrete tends to shrink. However, no clear trend can be
seen on the effects of water to cementitious materials ratio on shrinkage of concrete.

(3) For the four concrete mixtures with Georgia granite aggregate, shrinkage strain is slightly
lower than the four corresponding concrete mixtures with Miami Oolite limestone
aggregate. Lightweight aggregate concrete shrinks more than normal weight aggregate
concrete. This might be explained by their difference in elastic modulus. The concrete
with higher elastic modulus would have a stronger resistance to the movement caused by
shrinkage of cement paste.

(4) For the concretes tested, there appeared to be a relationship between the compressive
strength ( f) at the age when shrinkage test was started and the shrinkage strain (,h ) at
91 days as follows:

-0.0001 '
sh = 0.0005 1 e
sh
Where fi is in unit of psi.
(5) For the concretes tested, there appeared to have a relationship between elastic modulus
(Ec) at the age when shrinkage test was started and the shrinkage strain (,h ) at 91 days
as follows:

-2x107. .E
E h = 0.0007- e2x10 .E,

Where E, is in unit of psi.
(6) According to the shrinkage test results from this study, the C.E.B-F.I.P model (as shown
in Equation 6-6) appeared to give better predictions than the ACI 209 model (as shown in
Equation 6-3). Using ACI 209 model may result in over-estimation of the ultimate
shrinkage strain.

(7) For the concrete investigated in this study, the ultimate shrinkage strain ranged from
1.93 x 104 to 3.64x 104 for the concretes with Miami Oolite limestone aggregate; from
2.18x10-4 to 2.83x10-4 for the concretes with Georgia granite aggregate; and from
3.49x 104 to 4.22x 104 for the concretes with Stalite lightweight aggregate concrete.









CHAPTER 7
ANALYSIS OF CREEP TEST RESULTS

7.1 Introduction

This chapter presents the results from creep tests on the fourteen concrete mixes evaluated

in this study. The effects of various factors on creep behavior of concrete were analyzed.

Empirical equations relating creep to other fundamental properties, such as compressive strength

and elastic modulus, were established through regression analysis. Evaluation was made on

C.E.B-F.I.P model and ACI 209 model for their effectiveness and accuracy in creep prediction.

Ultimate creep strain was approximated using a three-parameter asymptotic equation to fit

experimental data, and ultimate creep coefficient was computed using ultimate creep strain

divided by instantaneous strain.

7.2 Analysis of Creep Test Results

The measured and calculated results from the creep tests on the fourteen concrete mixes

evaluated in this study were presented in Table B-1 in Appendix B. The results presented

include the total strain, shrinkage strain, creep strain, elastic strain, creep coefficient and creep

modulus at various loading ages.

7.2.1 Effects of Curing Conditions on Creep Behavior of Concrete

As shown in Figure 7-1 and Figure 7-2, the curing condition has a significant effect on the

creep behavior of such concrete mixtures as Mix-iF, Mix-2F, Mix-3F, and Mix-4F. Generally,

the concrete specimens moist-cured for 14 days had creeping strains which were less than those

moist-cured for 7 days by more than 13 percent. This observation applies to the specimens

loaded at both 40% of compressive strength and 50% of compressive strength at the two given

loading ages. Also, it is of significance to mention that, for ultra-high strength concrete, the

effect of curing condition on creep strain is extremely important. For example, the specimens









from Mix-1F moist-cured for 14 days have creep strain at 91 days over 25 percent less than those

moist-cured for 7 days. This is due probably to its high cementitious materials content, 1000 lbs

per cubit yard, and low water to cementitious ratio of 0.24. Thus, long-term moist curing

condition is needed to make cement hydration as complete as possible.

The tremendous effects of curing conditions on creep behavior also extend to the concrete

mixtures with lightweight aggregate, such as Mix-9LF and Mix-1OLS. For example, the creep

strain of Mix-9LF moist-cured for 14 days and loaded at 50% of compressive strength is

0.000749, which is 29.8% lower than that of Mix-9LF moist-cured for 7 days and loaded at the

same loading level. The creep strain of Mix-O1LS moist-cured for 14 days and loaded at 50% of

compressive strength is 0.000776, which is 47.3% lower than that of Mix-O1LS moist-cured for

7 days and loaded at 50% of its compressive strength.

However, no substantial effect of curing condition on creep strain was seen from the

concrete mixtures containing ground granulated blast-furnace slag as mineral additives. For

example, the creep strain of Mix-5S moist-cured for 14 days is nearly identical to that of Mix-5S

moist-cured for 7 days. This similar situation can also be seen from Mix-6S, Mix-7S and Mix-

8S. The cause can be attributed probably to the fact that the slag concretes nearly develop their

compressive strength fully in 14 days. That is to say, in comparison with the compressive

strength at 14 days, slag concrete mixtures have no significant increase in compressive strength

at age of 28 days. That means the specimens moist-cured for 14 days has no significant change in

microstructure in comparison with those moist-cured for 7 days. Thus, creep strains of slag

concretes obtained under two different curing conditions show no significant difference.












1.40E-03
E 7-day moist curing
0 14-day moist curing
1.20E-03


1.00E-03
-D

8.00E-04


/ 6.00E-04


o 4.00E-04 -- -- -


2.00E-04


0.00E+00
1F 2F 3F 4F 5S 6S 7S 8S 9LF 10LS
Mixture


Figure 7-1 Effects of curing condition on creep of concrete loaded at 40% of compressive
strength


1.60E-03i
O 7-day moist curing
S14-day moist curing
1.40E-03


1.20E-03


1.00E-03 -- ----- ---


8.00E-04

6.00E-04 ::


4.00E-04 ---- -------


2.00E-04 '


0.00E+00
1F 2F 3F 4F 5S 6S 7S 8S 9LF 10LS
Mixture


Figure 7-2 Effects of curing condition on creep of concrete loaded at 50% of compressive
strength









7.2.2 Effects of Loading Condition on Creep Behavior of Concrete

The effects of stress level on creep of the concretes investigated in this study are presented

in Figure 7-3 and Figure 7-4.

As shown in Figure 7-3 and Figure 7-4, the concrete specimens loaded at 50% of

compressive strength develop considerably higher creep strain than those loaded at 40% of

compressive strength at loading age, and the significant effects of stress level on creep strain can

be seen from both the normal weight aggregate concretes and lightweight aggregate concretes.

As shown in Table 7-1, for the concrete mixtures with fly ash, after 7 days moist curing the

specimens of Mix-1F loaded at 50% of compressive strength have creep strain of 0.00093, nearly

20% higher than those loaded at 40% of compressive strength. The 7-day moist-cured specimens

from Mix-2F loaded at 40% of compressive strength have creep strain at 91 days 18.5 percent

less than those loaded at 50% of compressive strength. For Mix-3F and Mix-4F, creep strain of

specimens moist-cured for 7 days and loaded at 40% of compressive strength is 31.6% and

22.7% lower than those of the same concretes moist-cured under the same condition but loaded

at 50% of compressive strength.

For the concrete mixtures with slag, creep strains of Mix-5S, Mix-6S, Mix-7S and Mix-8S

moist-cured for 7 days and loaded at 50% of compressive strength are 22.8%, 11.9%, 17.2%, and

16.3% higher than those of the same corresponding concretes cured under the same condition but

loaded at 40% of compressive strength.

Significant effects of loading conditions on creep behavior can also be observed from the

specimens moist-cured for 14 days. For the fly ash concretes, the specimens of Mix-iF, Mix-2F,

Mix-3F and Mix-4F moist-cured for 14 days and loaded at 50% of compressive strength creep

12.7%, 22.1%, 18.5% and 18.5% higher than those of the same corresponding concretes loaded














at 40% of compressive strength correspondingly. For slag concretes, the creep strains of Mix-5S,


Mix-6S, Mix-7S and Mix-8S moist-cured for 14 days and loaded at 50% of compressive strength


are 18.3%, 16.1%, 16.4% and 18.6% higher than those of the same corresponding concretes


loaded at 40% of compressive strength.


In addition, significant effect of loading condition on creep behavior can be seen from the


concrete mixtures with granite aggregate. For example, in comparison with the specimens loaded


at 40 percent of compressive strength, the creep strain of the specimens loaded at 50 percent of


compressive strength is over 23% higher.


Similar observation can also be seen from the concrete mixtures with lightweight


aggregate.


1.60E-03


1.40E-03


1.20E-03
C)

-o
S1.00E-03
O,

.s 8.00E-04


C- 6.00E-04
0

4.00E-04


2.00E-04


O.OOE+00


: - -.- .. - .. -.
1F 2F 3F ...
...i...tu..r...
::i~~iU : :R~iU :: i~~ C ... ... ... ... :: ~~iCU ::Rii ~ : :
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .





1F 2F 3F 4F 5S 6S 7S 8S 9LF 1OLS

Mixture


Figure 7-3 Effects of stress level on creep of concrete moist-cured for 7 days


E 40% of compressive strength
050% of compressive strength










1.40E-03
5 40% of compressive strength
E 50% of compressive strength
1.20E-03

1.00E-03

8.00E-04

6.00E-04

6 4.00E-04

2.00E-04

0.00E+00



Mixture


Figure 7-4 Effects of stress level on creep of concrete moist-cured for 14 days

7.2.3 Effects of Aggregate Types on Creep Behavior of Concrete

The effect of two different normal coarse aggregates on creep behavior was investigated on

four typical concrete mixtures, i.e. Mix-2F, Mix-3F, Mix-5S and Mix-7S. These mixes used a

Miami Oolite limestone as coarse aggregate. The four concrete mixtures with Georgia granite

aggregate were labeled as Mix-2GF, Mix-3GF, Mix-5GS, and Mix-7GS. The creep behavior of

these concrete mixtures was compared under the same curing conditions and loading conditions.

As shown in Figures 7-5 through 7-8, the comparison between Mix-2F and Mix-2GF, Mix-3F

and Mix-3GF, Mix-5S and Mix-5GS, and Mix-7S and Mix-7GS indicate that Mix-2GF, Mix-

3GF, Mix-5GS, and Mix-7GS creep slightly more than the corresponding Mix-2F, Mix-3F, Mix-

5S and Mix-7S for all loading conditions. This agrees with the findings from the study by G.E.

Troxell et al [G.E. Troxell et al, 1958]. He carried out the study on the effect of six different

types of aggregate on creep behavior of concrete. The results indicate that the concrete with

153











limestone aggregate has the lowest creep strain in comparison with the concretes with other types

of coarse aggregates, including quartz, granite, gravel, basalt and sandstone.

In addition, the concrete mixtures with lightweight aggregate, such as Mix-9LF and Mix-

10LS, do not creep as much as the concrete mixtures with normal weight aggregate. As can be

seen from Table 7-1, Mix-9LF and Mix-1OLF develop much less creep strain than the concrete

mixtures, such as Mix-2F, 3F, 4F, 5S, 6S, 7S, and 8S, even though the compressive strengths of

Mix-9LF and Mix-LS are considerable lower than those of concrete mixtures with normal weight

aggregate. These results agree with the conclusion made by A.M. Neville [A.M. Neville, 1996],

which stated that, as a general rule, the creep of structural quality lightweight aggregate concrete

is about the same as that of concrete made with ordinary aggregate.


1.50E-03



1.20E-03



c 9.00E-04

(U,

o 6.00E-04



3.00E-04



0.00E+00


10 20 30 40 50
Time (days)


60 70 80 90


Figure 7-5 Effects of aggregate type on creep behavior of Mix-2F


S-*-Georgia granite-40%-28-day curing
--Georgia granite-50%-28-day curing
-A-Miami Oolite limestone-40%-28-day curing
-x- Miami Oolite limestone-50%-28-day curing













1.20E-03


1.00E-03



8.00E-04



S6.00E-04



4.00E-04



2.00E-04


0.00E+00


0 10 20 30 40 50 60 70 80 90 100
Time (days)



Figure 7-6 Effects of aggregate type on creep behavior of Mix-3F


1.50E-03 I I


1.20E-03


9.OOE-04




6.OOE-04


3.OOE-04




0.OOE+00


0 10 20 30 40 50 60 70 80 90 100
Time (days)



Figure 7-7 Effects of aggregate type on creep behavior of Mix-5S


-*Georgia granite-40%-28-day curing
- Georgia granite-50%-28-day curing
SMiami Oolite Limestone-40%-28-day curing
SMiami Oolite limestone-50%-28-day curing


- Georgia granite-40%-28-day curing
-eGeorgia granite-50%-28-day moist curing
SMiami Oolite limestone-40%-28-day curing
SMiami Oolite limestone-50%-28-day curing











1.50E-03


1.20E-03



- 9.00E-04



o 6.00E-04



3.00E-04



0.00E+00


0 10 20 30 40 50 60 70 80 90 100
Time (days)


Figure 7-8 Effects of aggregate type on creep behavior of Mix-7S

7.2.5 Effects of Water to Cement Ratio and Air Content on Creep Strain

The main component of creep in concrete is from creep of the hydrated cement paste.

Creep is related to internal movement of absorbed or intracrystalline water, i.e. to internal

seepage [A.M.Neville, 1996]. Glucklich's study has shown that concrete from which all

evaporable water has been removed exhibits practically no creep [J. Glucklich, 1962]. Thus,

water to cementitious materials ratio gives a significant effect on the magnitude of creep strain.

Also, voids in the concrete play a critical role in influencing creep behavior of concrete because

internal seepage of water from the absorbed layers to voids such as capillary voids is quite

possible. A.M.Neville [A.M.Neville, 1996] stated that creep appears to be a function of the

relative amount of the unfilled space, and that the voids in the gel govern creep in concrete.

The effects of water to cementitious materials ratio and air content on creep of concrete are

illustrated in Figures 7-9 through 7-12. From these figures, it can be seen that creep of concrete

156


----- ---




-*-Georgia granite-40% loading level
S--Georgia granite-50% loading level
-Miami Oolite limestone-40% loading level
-x-Miami Oolite limestone-50% loading level









increases as water to cementitious materials ratio increases. It can also been seen from these

figures that the creep strain increases with increase of air content of fresh concrete, even though

air content of fresh concrete may not be directly related to the void content of hardened concrete.

7.2.6 Relationship between Compressive Strength and Creep Strain

It is always desirable in practice to find the relationship between compressive strength and

creep strain. If a simple relationship can be found between compressive strength and creep, it is

not necessary to consider the effect of type of cement, aggregate content and aggregate type,

water to cement ratio, air content and age on creep behavior separately. In addition, possible

accurate estimation on creep strain based on characteristic strength of concrete will make us free

from time-consuming creep test.

In Figure 7-13, compressive strength of concrete at 14 days is plotted against creep strain

at 91 days for the concretes moist-cured for 7 days and loaded at 40% and 50% of compressive

strength. In Figure 7-14, the compressive strength of concrete at 28 days is plotted against creep

strain at 91 days for the concretes moist-cured for 14 days and loaded at 40% and 50% of

compressive strength. As seen from Figure 7-13 and Figure 7-14, the creep strain decreases with

increase of compressive strength of concrete. Regression analysis was performed to determine

the relationship between compressive strength and creep strain at 91 days using following simple

linear function

Ec91 =a fc (7-1)

The results of the regression analysis are presented in Table 7-2.

As shown in Table 7-2, loading condition has a significant influence on the slope and

interception of the above linear equation, while curing age has nearly no effect on the slope and

interception. That is to say, the relationship between compressive strength and creep strain











obtained under the load at 40% of compressive strength can be expressed as one single linear


equation regardless of what curing condition was applied to the specimens. The same conclusion


also applies to concrete specimens loaded at 50% of compressive strength. The above hypothesis


is confirmed by the results of regression analysis given in Table 7-1, and also shown in Figure 7-


15.


In addition, instantaneous strains of normal-weight aggregate concrete are plotted against


compressive strength of concrete at corresponding curing ages in Figure 7-16. It indicates that


instantaneous strain measured in creep test increases with increase of compressive strength of


concrete.


1.40E-03


1.20E-03


1.00E-03


8.00E-04


6.00E-04

A tAAM" t A


'-t.UUr_-U'-t


2.OOE-04


0.OOE+00
0.20


0.25 0.30 0.35 0.40 0.45
Water to Cementitious Materials Ratio


Figure 7-9 Effects of water to cementitious materials ratio and air content on creep of concrete
moist-cured for 7 days and loaded at 40% of compressive strength


A high air content
* low air content
A


e TTa A ^
^^ ^ a


0.50












1.50E-03


1.20E-03


9.00E-04



6.00E-04


3.00E-04



0.OOE+00 -
0.20


0.25 0.30 0.35 0.40 0.45
Water to Cementitious Materials Ratio


Figure 7-10 Effects of water to cementitious materials ratio and air content on creep of concrete
moist-cured for 7 days and loaded at 50% of compressive strength


1.20E-03


1.00E-03


8.00E-04


6.00E-04


4.00E-04


2.00E-04


0.OOE+00
0.20


0.25 0.30 0.35 0.40 0.45
Water to Cementitious Materials Ratio


Figure 7-11 Effects of water to cementitious materials ratio and air content on creep of concrete
moist-cured for 14 days and loaded at 40% of compressive strength


0.50


A high air content
N low air content





a a


0.50


i i i i i











2.00E-03


1.60E-03


1.20E-03



8.00E-04


4.00E-04



0.00E+00


0.20 0.25 0.30 0.35 0.40 0.45 0.50
Water to Cementitious Materials Ratio


Figure 7-12 Effects of water to cementitious materials ratio and air content on creep of concrete
moist-cured for 14 days and loaded at 50% of compressive strength


Table 7-1 Regression analysis on relationship between compressive strength and creep strain
using Ecuation 7-1


Curing Loading
condition condition


14-day 40%


95% Confidence
c Interval
-1.19E-07~
-8.57E-08 .2E-
-5.29E-08
-1.62E-07-
-1.20E-07 E-0
-7.75E-08
-1.23E-07-
-9.27E-08 .2 0
-6.29E-08
-1.46E-07-
-1.11E-07
-7.62E-08
-1.10E-07
-8.99E-08 .94E
-6.94E-08
-1.39E-07-
-1.13E-07 E-0
-8.80E-08


95% Confidence
j3 Interval
1.54 3 1.28E-03 ~
1.54E-03
1.81E-03
1.65E-03 ~
1.98E-03
2.32E-03
1.35E-03 ~
1.59E-03 35E-03
1.84E-03
1.67E-03 ~
1.95E-03
2.24E-03
57E-03 1.41E-03
1.57E-03
1.74E-03
1.75E-03 ~
1.95E-03 2.16E-03
2.16E-03


R Syx

0.69 8.38E-05

0.72 1.08E-04

0.70 8.70E-05

0.71 1.01E-04

0.70 8.33E-05

0.71 1.03E-04


A high air content
Slow air content


Aa


7-day
moist
curing


40%

50%


moist
curing


All curing
conditions


50%

40%

50%












1.80E-03


1.50E-03
1.50E-03 -- -7-day-50%



1.20E-03



9.00E-04 -- -- --c^^, 0 n ^ --- --
3 9.00E-04



(C 6.00E-04



3.00E-04



0.00E+00
4000 5000 6000 7000 8000 9000 10000 11000 12000
Compressive Strength at loading age


Figure 7-13 Relationship between compressive strength and creep strain of concrete moist-cured
for 7 days


1.80E-03



1.50E-03



1.20E-03



. 9.00E-04


0)
S6.00E-04



3.00E-04


0.00E+00 !
5000 6000 7000 8000 9000 10000 11000 12000
Compressive Strength at loading age


Figure 7-14 Relationship between compressive strength and creep strain of concrete moist-cured
for 14 days












1.80E-03 I

o 40% loading level
S50% loading level
1.50E-03



6 1.20E-03 -- >- -



.- 9.00E-04 0
o o


S6.00E-04 o "-




3.00E-04



0.00E+00
4000 5000 6000 7000 8000 9000 10000 11000 12000
Compressive Strength (psi)



Figure 7-15 Relationship between compressive strength and creep strain of concrete under all
curing conditions


1.20E-03
S40% of compressive strength
o 50% of compressive strength
1.00E-03

F-
o

S8.00E-04 -
E 0
0 0
*| 6.00E-04 --.

IP
0
c 4.00E-04

cu

2.00E-04



0.00E+00
5000 6000 7000 8000 9000 10000 11000 12000
Compressive Strength (psi)



Figure 7-16 Relationship of compressive strength to instantaneous strain measured in creep test



162









7.3 Creep Coefficient

Creep coefficient, which is calculated by dividing creep strain by elastic strain, is a very

important parameter in prestressed concrete design. Creep coefficient is significantly affected not

only by those factors influencing creep strain, but also by the elastic property of concrete.

7.3.1 Effects of Loading Conditions on Creep Coefficient

For the specimens moist-cured for 7 days, the creep coefficients obtained from two

different stress levels are plotted in Figure 7-17 for ten concrete mixtures. It shows that two

different stress levels have nearly no effect on the creep coefficient of all the concrete mixtures.

The same observation can be seen from the specimens moist-cured for 14 days as well, as shown

in Figure 7-18.

In this study, two stress levels include 40% of compressive strength and 50% of

compressive strength. Thus, the conclusion can be arrived that the ratio of creep strain to

instantaneous strain of concretes investigated in this study is proportional to the stress applied up

to 50% of compressive strength at loading age.

7.3.2 Effects of Curing Conditions on Creep Coefficient

Curing conditions have some effects on creep coefficient. As shown in Figure 7-19, the

effects of curing conditions on creep coefficients of Mix-iF, Mix-2F, and Mix-3F are substantial.

For example, the creep coefficient of Mix-1F moist-cured for 14 days is 0.81 at 91 days, which is

35.8% lower than that of Mix-1 moist-cured for 7 days. Also, the creep coefficients of Mix-2F

and Mix-3F moist-cured for 14 days are 23.9% and 17.7% lower than those of the same

corresponding concretes moist-cured for 7 days. However, for some concrete mixtures, such as

Mix-6S, Mix-7S, Mix-8S, and Mix-4F, the effects of curing conditions on creep coefficient are

not very appreciable. For instance, the creep coefficients of Mix-6S, Mix-7S, Mix-8S and Mix-

4F moist-cured for 14 days are just about 10% lower than those of them moist-cured for 7 days.

163












The cause can be attributed to the fact that there was not too much additional strength


development from the age of 14 days to the age of 28 days for the slag concretes.


2.00
0 40% of compressive strength
1 50% of compressive strength
I Difference

1.50




1.00






















340% of compressive strength
1F 2F 3F 4F 5S 6S 7S 8S 9LF 1erence LS


















-0.50 --- -- -- -- -- -- -----.-- --::--:--
-0.50

















Mixture



Figure 7-18 Effects of stress level on creep coefficient of concrete moist-cured for 14 days
0.00



0.50















0 0.50
Mixture



Figure 7-17 Effects of stress level on creep coefficient of concrete moist-cured for 7 days


2.00








-1.50














Mixture



Figure 7-18 Effects of stress level on creep coefficient of concrete moist-cured for 14 days










The effects of curing condition on creep coefficient of lightweight aggregate concrete are

very significant. For instance, the creep coefficient of Mix-9LF moist-cured for 14 days is about

1.14, nearly 18% lower than that of Mix-9LF moist-cured for 7 days. Also, the specimens of

Mix-O1LS moist-cured for 14 days has creep coefficient of 1.13, which is over 42% lower than

1.61, creep coefficient of Mix-6 moist-cured for 7 days. Thus, apparently, longer curing time can

decrease creep coefficient tremendously for lightweight aggregate concrete.


2.00

1.80

1.60

1.40

1.20

1.00

0.80

0.60

0.40

0.20

0.00


1F 2F 3F 4F 5S 6S 7S 8S 9LF 10LS
Mixture


Figure 7-19 Effects of curing condition on creep coefficient of concrete

7.3.3 Effects of Water Content on Creep Coefficient

Since water content of fresh concrete affect significantly drying creep of concrete, they

should have considerable effects on creep coefficient as well. As can be seen from Figure 7-20,

water content of fresh concrete have significant effects on creep coefficient of concrete at 91

days. Creep coefficient at 91 days increases as water content of fresh concrete increases.











2.50


2.00
cj
-o
S1.50



C 1.00
O-
O

0.50



0.00


100 150 200 250 300 350 400
Water Content (Ibs/yard3)


Figure 7-20 Effects of water content on creep coefficient at 91 days

7.3.4 Effects of Compressive Strength at Loading Age on Creep Coefficient

As shown in Table 7-1, the higher the compressive strength of concrete is at the loading

age, the lower the creep coefficient is. For example, for the concrete mixtures with Miami Oolite

limestone aggregate, Mix-1 has the highest compressive strength, and it has the lowest creep

coefficient. Also, it is of great importance to see that the creep coefficient is not affected by the

loading conditions, i.e. the creep coefficient obtained under the loading condition of 40% of

compressive strength is identical to that obtained under the loading condition of 50% of

compressive strength.

To find out how the compressive strength of concrete at loading age is related to the creep

coefficient at 91 days, compressive strength at loading age was plotted against corresponding

creep coefficient at 91 days in Figure 7-21 and Figure 7-22, for specimens loaded at 14 days and


o Miami Oolite limestone
* Georgia granite
A Stalite lightweight aggregate




Go8


A


i i i i i


-










28 days, respectively. Then linear regression analysis using Equation 7-2 was performed, and the

analyzed results are displayed in Table 7-2.

(P, =a f, + P (7-2)

Where ypc = creep coefficient at 91 days; f, = compressive strength; ac and 3 = the slope and

interception of linear equation.

Table 7-2 Regression analysis on relationship of compressive strength to creep coefficient using
Equation 7-2
95% 95%
Curing condition a Confidence p Confidence R2 Syx
Interval Interval
-2.39E-04 ~
14-day curing -2.02E-04 -1.E-04 3.016 2.717 3.316 0.9041 0.0951
-1.64E-04
-2.43E-04 ~
28-day curing -2.06E-04 -.E-04 3.077 2.774 3.379 0.8855 0.1071
-1.69E-04
All curing conditions -2.03E-04 -1.79E-04 3.042 2.842 3.242 0.8919 0.0999
-1.79E-04

As can be seen from Table 7-2 as well as Figure 7-21 and Figure 7-22, compressive

strength of concrete at loading age is nearly linearly related to the creep coefficient at 91 days.

This situation is true for the specimens under two different curing conditions. Also, it is to be

noted that the slope and interception of the linear regression equations are nearly identical to one

another for the specimens under two different curing conditions. That is to say, once compressive

strengths of specific concrete mixtures are given, the creep coefficient can be computed using the

linear relationship between compressive strength and creep coefficient at 91 days regardless of

what curing condition was applied to the specimens.

Therefore, linear regression analysis was carried out on the experimental data obtained

from both curing conditions, and the analyzed results are plotted in Figure 7-23 and presented in

Table 7-2 as well. As can be seen from Table 7-2, the slope and interception of linear regression

equation from combined analysis are approximately equal to the average of slopes and

interceptions from separate analyses.














2.50


2.00






0.
1o50







1.00




0.50




0.00
2000 4000 6000 8000 10000 12000 14000
Compressive strength at 14 days (psi)



Figure 7-21 Relationship between compressive strength and creep coefficient for specimens
loaded at 14 days


2.50




2.00




S1.50
(Ds
0

D 1.00




0.50




0.00
400


10


6000 8000 10000 12000
Compressive Strength at 28 Days (psi)


14000


Second phase
o First phase






S






0










Figure 7-22 Relationship between compressive strength and creep coefficient for specimens
loaded at 28 days

2.50
O Limestone
S Granite
2.00


S1.50







0.50



0.00
4000 6000 8000 10000 12000 14000
Compressive Strength (psi)


Figure 7-23 Relationship between compressive strength at loading age and corresponding creep
coefficient at 91 days

7.3.5 Relationship between Elastic Modulus at Loading Age and Creep Coefficient

After realizing the close relationship between compressive strength and creep coefficient, it

is not difficult to note that because, for a given concrete, compressive strength and elastic

modulus is related, creep coefficient and elastic modulus should be related as well.

As shown in Figure 7-24, elastic modulus was plotted against creep coefficient at 91 days

for the concrete with normal-weight aggregate. A linear regression analysis was performed using

Equation 7-3.

p, = a E +p/ (7-3)

The results of the regression analysis are shown in Table 7-3. As can be seen from Figure

7-24, for the normal-weight aggregate concrete, creep coefficient at 91 days is linearly related to










the elastic modulus at the loading age, while for lightweight aggregate concrete creep coefficient

can not be related to elastic modulus using the linear equation from normal-weight aggregate

concrete. More data from creep test on lightweight aggregate concrete are needed to establish

reliable relationship between elastic modulus and creep coefficient for lightweight concrete.

In addition, creep coefficient at 91 days was plotted against the ratio of compressive

strength and elastic modulus in Figure 7-25. It indicates that creep coefficient at 91 days is

linearly related to the ratio of compressive strength to elastic modulus of concrete at loading age.

A linear regression analysis was performed to relate creep coefficient to the ratio of compressive

strength to elastic modulus by the following equation:


C = fa + (7-4)
E


The results of the regression analysis are presented in Table 7-4.


2.40
o Normal weight aggregate
20* Lightweight aggregate
2.00 N_

0 oc cP
1.60 -0--

o 0
1.20
# oo
S** 00

0.80
0 0\

0.40


0.00
2.00E+06 3.00E+06 4.00E+06 5.00E+06 6.00E+06 7.00E+06 8.00E+06
Elastic Modulus at Loading Ages (psi)


Figure 7-24 Effects of Elastic modulus at loading age on creep coefficient at 91 days











2.50


2.00
U,
o
) 1.50

Ea,

o 1.00
0
a,


0.50



0.00


0 0.0005 0.001 0.0015 0.002 0.0025 0.003


Figure 7-25 Relationship between creep coefficient at 91 days and f,/E

Table 7-3 Regression analysis on relationship of elastic modulus to creep coefficient using
Equation 7-3
95% 95% 2 S
0 R SSE
confidence interval confidence interval
-5.67E-07 3.151
-4.55E-07 3 7 3.725 0.6671 0.1742
-3.43E-07 4.299

Table 7-4 Regression analysis on relation of creep coefficient to fo/E using Equation 7-4
95% 95% R2 SSE
confidence interval confidence interval
-1609 3.010
-1132 3.485 0.7026 0.1647
-1014 3.959

7.3.6 Effects of Coarse Aggregate Type on Creep Coefficient

As can be seen from Figure 7-26, the creep coefficients of concretes made with Georgia

granite is higher than those of concretes with Miami Oolite limestone aggregate. This is due

probably to the lower elastic deformation of concretes with Georgia granite aggregate in

comparison with those with Miami Oolite limestone aggregate. Therefore, the ratio of creep










strain to elastic strain is larger for Georgia granite aggregate concrete. However, lightweight

aggregate concrete behaves in a different way in comparison with Georgia granite aggregate

concrete. Since the elastic deformation of lightweight aggregate concrete is significantly higher

than that of Georgia granite aggregate concrete and Miami Oolite limestone aggregate concrete,

the ratio of creep strain to elastic strain is lower for lightweight aggregate concrete. This

observation is in agreement with the conclusion given by Neville [A.M. Neville, 1996].


2.00
E Miami Oolite limestone
1.80 1 Georgia granite_

1.60

1.40

m 1.20

1.00









0.00
o 0.80

0.60
a-
0.40

0.20

0.00
Mix-2 Mix-3 Mix-5 Mix-7
Mixture

Figure 7-26 Effects of coarse aggregate type on creep coefficient at 91 days

7.4 Creep Modulus

Creep modulus, defined as the ratio of stress applied to concrete specimen to the total

strain excluding shrinkage strain, reflects the decay of stiffness with time. Apparently, this

parameter is of great important in inelastic structural material analysis to obtain time-dependent

elastic modulus so that accurate deformation of material can be computed correctly using the










reduced elastic modulus. Figure 7-27 presents a typical decay curve of concrete mixture

investigated in this study.

As can be seen from Table 7-1, for the fly ash concrete mixtures, curing condition has

significant effects on the creep modulus as a function of time. That is to say, the decay of creep

modulus of specimen moist-cured for 14 days is considerably less than that of the same concrete

moist-cured for 7 days. The same observation can also be made on the lightweight aggregate

concrete as well. This indicates that curing condition plays a very significant role in decreasing

creep strain of fly ash concrete and lightweight aggregate concrete.

However, for the slag concrete mixtures, no appreciable effects of curing condition on

creep modulus can be observed. This means that a longer curing time beyond 14 days has no

significant influence on the creep behavior of slag concrete.


6.00E+06

-- 7-day moist curing-40% of compressive strength
--7-day moist curing-50% of compressive strength
5.00E+06 -- 14-day moist curing-40% of compressive strength
14-day moist curing-50% of compressive strength


4.00E+06



3.00E+06 --



2.00E+06 ----



1.00E+06



0.00E+00


0 10 20 30 40 50
Time (days)


60 70 80 90 100


Figure 7-27 Typical decay curves of creep modulus with time









7.5 Prediction of Ultimate Creep Strain

It is often assumed that creep rate for a concrete material decreases with time, and the

creep strain will approach a limiting value after an infinite time under load. The study by G.E.

Troxell et al [G.E.Troxell et al, 1958] indicates that the average value of creep strain after 30

years is 1.36 times the one-year creep strain. In engineering practical point of view, it is often

assumed that the 30-year creep strain represents the ultimate creep stain.

The ultimate creep strain of concrete investigated in this study was determined using

asymptotic equation, given as follows, to fit the experimental data.


c =_a (7-5)


This equation is the ratio of two polynomials. As the time variable approaches infinity, the

ratio of two polynomials will be equal to 1. Therefore, ultimate creep strain is equal to a.

In this equation, a and 3 are two parameters to be determined from curve-fitting, and y,

which is the factor borrowed from CEB-FIP Equation, reflects the effect of geometrical

characteristics of specimen and relative humidity on creep behavior of concrete. The relative

humidity was controlled at 75% in this study. 6"x 2" cylindrical specimens were used for creep

tests. The geometric characteristic of the test specimen, h, can be computed as follows:

2Ac 2x"xx32
h = 2 2= 3in = 76.2mm (7-6)
u "x6

Then, y can be obtained as follows:

( 175% 8 h
=150- 1+1.2.-- +250=381.5<1500 (7-7)
y 0100% 100

Thus, the equation used to fit the experimental data becomes










t >8
sc =a. (7-8)
Sa t +381.5 (


Least Squares Method of curve fitting as described in Chapter 6 was used to determine two

unknown parameters, ac and p. Ultimate creep strains and ultimate creep coefficient after

regression analysis for 14 concrete mixtures are presented in Table 7-5.

Table 7-5 The predicted ultimate creep strain and creep coefficient
Predicted items Ultimate creep strain ultimate creep coefficient
Curing conditions curing condition 1 Curing condition 2 curing condition 1 Curing condition 2
Loading conditions 40% 50% 40% 50% 40% 50% 40% 50%
Mix-IF 1.06E-03 1.30E-03 0.88E-03 1.03E-03 1.48 1.55 1.14 1.16
Mix-2F 1.93E-03 2.08E-03 1.66E-03 2.11E-03 2.91 2.59 2.37 2.44
Mix-3F 1.45E-03 1.86E-03 1.39E-03 1.56E-03 2.30 2.40 2.11 1.90
Mix-4F 1.37E-03 1.59E-03 1.24E-03 1.63E-03 2.28 2.14 2.14 2.32
Mix-5S 1.40E-03 1.84E-03 1.25E-03 1.64E-03 2.10 2.17 1.74 1.84
Mix-6S 1.68E-03 1.87E-03 1.55E-03 1.75E-03 2.51 2.23 2.23 2.05
Mix-7S 1.41E-03 1.69E-03 1.46E-03 1.60E-03 2.71 2.71 2.61 2.46
Mix-8S 1.58E-03 1.97E-03 1.45E-03 1.95E-03 2.57 2.72 2.21 2.34
Mix-9LF 1.11E-03 1.40E-03 0.99E-03 1.16E-03 1.78 1.83 1.46 1.49
Mix-O1LS 0.94E-03 1.19E-03 0.76E-03 0.97E-03 1.61 1.45 1.32 1.26
Mix-2GF --- --- 1.80E-03 2.10E-03 --- --- 2.99 2.70
Mix-3GF --- --- 1.57E-03 1.81E-03 --- --- 2.96 2.72
Mix-5GS --- --- 1.42E-03 1.77E-03 --- --- 2.51 2.55
Mix-7GS --- --- 1.49E-03 1.76E-03 --- --- 2.89 2.69

As shown in Table 7-6, it is to be pointed out that most of the concretes investigated in this

study have an ultimate creep coefficient higher than 2.0.

7.6 Evaluation on Creep Prediction Models

The effectiveness of other creep prediction models, such as Burgers model, C.E.B-F.I.P

model and ACI 209 model, were evaluated in this study.

S Burgers model

Burgers Model or four-element model, as shown in Figure 7-28, was also used to fit the

experimental data to evaluate the feasibility of the Burgers model to predict creep strain of

concrete at a later time, based on the experimental data obtained in three months.











00


R1
81 -
ti t

---- --^~ .-- ---

SA' 83
R2 2 ..83. CA3


O ,1- D



Figure 7-28 Burgers Model

The total strain predicted by the Burgers model can be considered as the sum of the strain

responses of each element under the applied load, and can be expressed by the following

equation:

E = 8, + E2 + E3 (7-9)
Where ;1 is the elastic strain of spring in a Maxwell model, and it can be given as


1, (7-10)
Ri
82 is viscous flow of dash-pot in a Maxwell model, and its rate type formula can be expressed as


E, =- (7-11)

83 is the strain of a Kelvin unit, and it can be related to the applied stress as


E'3+ E3-- (7-12)
172 72

Eliminating 8, 82, and 83 from the above four equations, the constitutive relationship

between 8 and a in the Burgers model can be expressed as










a + 1 + +2 ,+ 1a-12 o 12 e" (7-13)
R1 R2 R2) RR2 R2

Solving the above second order differential equation with initial conditions of


R1
t = 0 -> = E3 =0 (7-14)
s'= + O
/71 /72

The creep behavior of Burgers model under the constant stress can be derived as:


E(t)= + t + 1- exp 2- t (7-15)
R, ,1 R2 /2 ))

In this study, only creep strain was considered. Thus, we can eliminate the first term in

Equation 7-9. Therefore, the strain in the Burgers model becomes:


E(t)= ao t + O 1- exp R2 t (7-16)
l7, R2 172 )

Three material constants, R2, rf and "2, can be easily determined by curve-fitting Equation

7-16 to the experimental data.

As can be seen from Equation 7-16, after a certain time, the second term on right side of


equation will decay and approaches -, and the creep rate will become a constant value, i.e.
R2

0 So, after a long time, the expression for the strain from the Burgers model can be simplified
771

as follows:


E(t) = o t + (7-17)
7, R,










Burgers model with constitutive parameters determined from regression analysis was

plotted in Figure 7-29. As can be seen from Figure 7-29, Burger's model is very capable to

simulate the development trend of creep of concrete. However, it indicates that the extrapolation

made by Burgers model results in overestimation of the ultimate creep strain. This is due the lack

of long-term creep data from this study. It is not possible to determine the constitutive

parameters accurately without long-term creep data.


1.50E-03



1.20E-03 -



.S 9.00E-04 -



S6.00E-04
/ 14-day-40%
o 14-day-50%
3.00E-04 -- Regression analysis
H' Burger's Model


0.00E+00
0 20 40 60 80 100
Time (days)


Figure 7-29 Prediction of strain using the Burger's model

* C.E.B-F.I.P Model (1990)

C.E.B-F.I.P Model is an empirical model recommended by Europe Union in 1990. In this

model, the creep strain can be predicted based on the information from ultimate compressive

strength and modulus of elasticity at loading age, and a time function determined according to

the mechanical properties of specific concrete mixture, the geometry of specimen, and the curing

conditions applied to the specimen, and so on. The general equation is given as follows:

178









Sc (t, to) = -(t, to) (7-18)
Ec,

For the detail description about C.E.B-F.I.P model, please refer to the literature review in

Chapter 2.

Finally, combining all the equations together and simplifying them, we have the following

equation used to predict the development of creep strain with time.

o- (to) 1-RH/RHo 5.3 1 (t-to)/t
ccr (t, to) E0.46. (h/h3) fJ f.1/ fcmo O.l+ (to t)0 2 H (t _t 1
E, 0. o46. (h Iyo fi r _)It,_1

(7-19)

In this study, the relative humidity is controlled at 75%. For 6"x 12" cylinder, the

geometrical characteristic of the test specimen, h, can be computed as follows:

2A 2xrx32
h = rx 3in = 76.2mm (7-20)
u ix6

Then, /,h can be obtained as follows:

18
75%o 76.2
/H =15.0 1+ 1.2- 75 ] 7. +250=381.5<1500 (7-21)
H 5 100%) 100

Then, the prediction formula can be simplified as follows:

For concrete cured for 14 days:


to) c(to) 18.55 (t -14) 0 (7-22)
8cr (t,t0) = K(7-22)
Ecl4 \fc. L 381.5 + (t 14)

The above equation is an asymptotic function. As time approaches infinity, creep strain

.. c(to) 18.55
will reach ultimate creep strain t ,j- .


Similarly, for the concrete specimen cured for 28 days, the prediction equation becomes

179











scr(t, to) = U-C(t0) 18.55 1. (t 28) .1o3 (7-23)
s )= (t, to) = (7-23)
Ec28 381.5 + (t 28)


As can be seen from the above equation, this asymptotic equation approaches a limiting

value as time approaches infinity. Therefore, ultimate creep strain can be computed by the

following formula:


u(to) 18.55 (7-24)
Ec28 m


To evaluate the effectiveness of the C.E.B-F.I.P model, the C.E.B-F.I.P Equation was

plotted in Figure 7-30. It indicates that C.E.B-F.I.P model gives very good prediction. To verify

this conclusion, the creep strain at 91 days from experimental measurements is plotted against

the creep strain computed according to C.E.B-F.I.P model in Figure 7-31. It clearly shows that

the measurements match very well with the predictions made by the C.E.B-F.I.P model.


1.50E-03
14-day-40%
o 14-day-50%
-- Regression analysis
1.20E-03 --- CEB-FIP model o
ACI 209 model .


c 9.00E-04 ..



0 6.00E-04



3.00E-04 --



0.00E+00
0 10 20 30 40 50 60 70 80 90 100
Time (days)


Figure 7-30 Comparison on the effectiveness of C.E.B-F.I.P model and ACI model












1.80E-03
A First phase
o Second Phase
1.50E-03

o0 y=x
1.20E-03 o
AO

9.00E-04 -o
2 00 2A

S6.00E-04 0---
0 0




3.00E-04 -


0.00E+00
0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 1.80E-03
Predicted Creep Strain at 91 days


Figure 7-31 Comparison between the creep strain at 91 days from experimental data and the
predicted creep strain using CEB-FIP model

Also, in order to verify if there is simple linear relationship between creep strain


and, the creep strain at 91 days was plotted against in Figure 7-31, where oy is
E- E- E


stress applied to the specimen; E is elastic modulus of concrete at loading age; and fcm is

characteristic strength of concrete at loading age. Then, a linear regression analysis was


performed to determine the relationship between creep strain at 91 days and and the



analyzed results are shown in Table 7-6. As can be seen from Figure 7-31, creep strain at 91 days


is linearly related to The regression equation is given as follows:




c91 =13.40- U -1.758x10-4 (7-25)
E7 If












Table 7-6 Regression analysis on relation of creep coefficient to

95% 95% 2
confidence interval confidence interval
11.21 ~ -3.649E-04 ~
13.40 1 -1.758E-04 6E 0.6848 1.193E-04
15.58 -1.333E-04



In addition, the ultimate creep strains predicted by curve-fitting to experimental data were

plotted against the creep strains calculated using the original C.E.B-F.I.P model in Figure 7-32. It

indicates that original C.E.B-F.I.P model gives very good creep strain prediction for the normal-

weight concrete mixtures investigated in this study.




1.80E-03


1.50E-03


> 1.20E-03 -0
o ~ o

/o 0


a 6.00E-04 P


3.00E-04


0.00E+00
0.00E+00 3.00E-05 6.00E-05 9.00E-05 1.20E-04 1.50E-04
c/(Exfe,, 0.5)


Figure 7-32 Relationship between creep strain and mechanical properties at loading age











3.00E-03


2.50E-03 -
S/ y=x
0) 0 0 a
S2.00E-03 --

00
I 1.50E-03 -.0-00
8
D 0






















given as follows:
28 (7-26)
S1.00E-03 C p COefficient
0
E

5.OOE-04________


0.00E+00 _-------
0.OOE+00 5.00E-04 1.00E-03 1.50E-03 2.00E-03 2.50E-03 3.00E-03
Predicted Ultimate Creep Strain by CEB-FIP model


Figure 7-33 Comparison between the ultimate creep strain calculated by C.E.B-F.I.P model and
that by curve-fitting

SACI-209R model

The evaluation on ACI 209 model was performed in this study. ACI 209 (1992) model is

given as follows:


(t- t)06
028 Q(, to)=0- ^(tot (7-26)
10 + (t to)06
Where


028 (t, to )- Creep coefficient at time t;


& (to) Ultimate creep coefficient;


to Time of loading. In this study, to = 14 days for concrete cured for 14 days before


loading; and to = 28 days for concrete cured for 28 days before loading.


The ultimate creep coefficient can be expressed as:


q.(to)= '. (7-27)









The constant & = 2.35 is recommended. The correction factors y, consist of the following

terms:

Yc = Ya YRH Yat Y. Yp Ya (7-28)

Where

Y1, Correction factor for loading age, which is equal to 0.916 for specimen cured for 14

days, and 0.814 for specimen cured for 28 days.

yRH Correction factor for ambient relative humidity. In this study, the ambient relative

humidity is 75%, thenyRH = 0.77.

y, Correction factor for slump of fresh concrete. y, = 0.82 + 0.00264 S, (S, is slump

in mm).

Yp Correction factor for fine to total aggregate ratio. /y = 0.88 + 0.0024 pa (Pa is fine

to total aggregate ratio)

/a Correction factor for air content. yT = 0.46 + 0.09 a, (a, is air content)


Yt, Correction factor for thickness of member. In this study, the volume-surface ratio

method is used to obtain y2,


2, = 3- 1+1.13 .e s (7-29)



Where


Volume to surface ratio in mm.
s

The correction factors based on the concrete mixtures, geometry of specimen and ambient

conditions employed in this study for the ACI 209 model are provided in Table 7-7.














Table 7-7 Correction factors for the ACI 209 model


14-day
moist
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814
0.814


Yc
Yrh Ys Ya Yat Yp 7-day
moist
0.77 1.34 0.57 1.00 0.88 0.30
0.77 1.32 0.87 1.00 0.88 0.45
0.77 0.92 0.69 1.00 0.88 0.36
0.77 1.02 0.64 1.00 0.88 0.33
0.77 1.31 0.80 1.00 0.88 0.42
0.77 1.05 0.66 1.00 0.88 0.34
0.77 1.09 0.96 1.00 0.88 0.50
0.77 1.00 0.80 1.00 0.88 0.41
0.77 0.82 0.73 1.00 0.88 0.38
0.77 0.82 0.93 1.00 0.88 0.48
0.77 1.12 1.13 1.00 0.88 0.58
0.77 0.99 0.60 1.00 0.88 0.31
0.77 1.26 0.96 1.00 0.88 0.50
0.77 0.97 0.80 1.00 0.88 0.41


14-day
moist
0.27
0.40
0.32
0.29
0.37
0.30
0.44
0.37
0.33
0.43
0.52
0.27
0.44
0.37


As can be seen from Figure 7-34, ACI 209 model greatly underestimates the creep strain of


the concretes investigated in this study.


1.80E-03



1.50E-03
0)
E
a0
I 1.20E-03
E
o
(,
9.00E-04

tO-
e 6.00E-04

U)
o 3.00E-04


0.OOE+00 K
0.00E+00


3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03


Calculated Creep strain at 91 days


Figure 7-34 Evaluation on ACI-209 model and C.E.B-F.I.P model


Mix

Mix-1F
Mix-2F
Mix-3F
Mix-4F
Mix-5S
Mix-6S
Mix-7S
Mix-8S
Mix-9LF
Mix-10LS
Mix-2GF
Mix-3 GF
Mix-5GS
Mix-7GS


Yla
7-day
moist
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916
0.916


1.80E-03









7.7 Summary of Findings


This chapter presents the results from the creep tests in this study. The following is a

summary of major findings from the creep tests:

(1) Curing condition has some effect on creep of fly ash concrete and lightweight aggregate
concrete, while its effect is very slight on slag concrete.

(2) For the stress levels used (40 and 50% of compressive strength), the measured creep
strain and instantaneous strain were linearly proportional to the stress applied. Thus, the
computed creep coefficients were not affected by the stress level in this study.

(3) Water to cementitious materials ratio has some effects on creep behavior of concrete. The
higher the water to cementitious materials ratio, the more the concrete creeps.

(4) For the concrete with identical water to cementitious materials ratio, the higher the air
content of fresh concrete, the more the concrete creeps.

(5) The concretes with granite aggregate creeps slightly more than the concretes with Miami
Oolite limestone aggregate and lightweight aggregate under the same stress level.
However, due to the much lower elastic modulus of lightweight aggregate concrete, the
creep coefficient of lightweight aggregate concrete is much lower than that of normal
weight aggregate concrete. Due to the higher elastic modulus of granite aggregate
concrete, creep coefficient of granite concrete was much higher than that of the concretes
with Miami Oolite limestone aggregate.

(6) A simple linear relationship was established between compressive strength at loading age
and creep strain at 91 days.

(7) A linear relationship was also found between creep coefficient at 91 days and
compressive strength (f,), elastic modulus (Ec), and the ratio of compressive strength
and elastic modulus. The regression equation related compressive strength at loading age
to creep coefficient at 91 days ((o91) is given as follows:


c91 = a* fc +/P (7-2)
Where a is equal to -2.03x10-4 and 3 equal to 3.042; f is in unit of psi.
The regression equation relating elastic modulus to creep coefficient at 91 days is given
as follows:

(pc91 = a E + p (7-3)

Where a is equal to -4.55x10.7 and 3 equal to 3.725; Ec is in unit of psi.









The equation related creep coefficient at 91 days to the ratio of compressive strength to
elastic modulus is given as follows:


(Pc91 _= c -- + (7-4)
Ec

With ac equal to -1132 and 3 equal to 3.485.

Among these regression equations, Equation 7-2 gave the best prediction.

(8) Ultimate creep coefficient of some of the concretes appeared to exceed 2.0. These
concrete mixtures included Mix-2F, Mix-3F, Mix-4F, Mix-5S, Mix-6S, Mix-7S, Mix-8S,
Mix-2GF, Mix-3GF, Mix-5GS and Mix-7GS.

(9) CEB-FIP model (as shown in Equation 7-17) appeared to give better prediction on the
creep behaviors of concretes investigated in this study than ACI 209 model (as shown in
Equation7-25).









CHAPTER 8
CONCLUSIONS AND RECOMMENDATIONS

8.1 Design of Creep Apparatus

Performance and characteristics of creep apparatus designed for this study are presented as

follows:

1) The creep apparatus designed in this study is capable of applying and maintaining a load
up to 145,0001bs on the test specimens with an error of less than 2%.

2) Three specimens can be stacked for simultaneous loading.

3) When a maximum load of 145,0001bs is applied, the deflection of bearing surfaces of the
header plates is less than 0.001in, and the pressure distribution on the test specimen
varies by less than 0.026%, or 1.5psi.

4) The creep testing procedures developed in this study was found to work very well. They
are given in detail in Section 4.3.

8.2 Findings from This Study

8.2.1 Strength and Elastic Modulus

1) Splitting tensile strengths of the concrete mixtures using granite aggregate were
significantly lower than those using Miami Oolite limestone aggregate. This is due
probably to the poor bonding condition between hardened cement paste and granite
aggregate.

2) Compressive strengths of concretes with granite aggregate were comparable to or lower
than those of concretes with Miami Oolite limestone aggregate.

3) The concrete with granite aggregate had higher elastic modulus than that with Miami
Oolite limestone aggregate, while the lightweight aggregate concretes had lower elastic
modulus than the normal weight concretes.

4) Fly ash concretes develop compressive strength and splitting tensile strength at a slower
rate than the slag concretes. Fly ash concrete shows significant strength gain after 28
days, while this was not seen from the slag concrete mixtures.

5) The ACI 209 Equation for prediction of compressive strength (f (t)) at various curing
age from compressive strength at 28 days (f,, (t)), which is given as follows, was
modified to give better strength prediction for the various mixtures.









t '
fc(t)= 4.0 +0.85t fc28

The modified equation has the following form for the concrete with different coarse
aggregates:

t
c(t) a+-t c2

The value of a was found to vary from 1.1 to 2.6 for the concretes with Miami Oolite
limestone aggregate, from 2.6 to 5.3 for the concretes with Georgia granite aggregate,
and from 4.2 to 6.7 for lightweight aggregate concretes; the value of 3 was found to vary
from 0.82 to 0.93 for the concretes with Miami Oolite limestone aggregate, from 0.82 to
0.89 for the concrete with Georgia granite aggregate, and from 0.74 to 0.82 for
lightweight aggregate concrete in this study.

6) The relationship between compressive strength ( f ) and splitting tensile strength (f, ) is
established for the concrete mixtures investigated in this study. The Carino and Lew
model, given as follows,
S)0.73

was modified to the following equation:
t )0.7185

Where f, and fc, are in units of psi.

7) The relationship between compressive strength and modulus of elasticity was refined in
this study using Least Square of Curve-fitting Technique. The ACI 318-89 Equation,
which is
Ec = 57000Ff
was modified to the following equation:


Where a is equal to 55,949 for Miami Oolite limestone aggregate; 62,721 for Georgia
granite aggregate; and 43,777 for Stalite lightweight aggregate. f, and Ec are in units of
psi.

8) For all three aggregate types investigated in this study, a modified ACI 318-95 prediction
equation was developed:
E = 30.16 w1 f + 484200
Where w is the density of concrete in pound per cubit foot. f" and E, are in units of psi.









8.2.2 Shrinkage Characteristics of Concretes Investigated


1) Fly ash concrete mixtures had slightly higher shrinkage strain at 91 days than slag
concretes. This is due probably to the slow hydration rate of fly ash in comparison with
that of slag. As a result of slower rate of hydration, there is more free water evaporating
from the interior of the concrete, which can cause the concrete to shrink more. Thus, it is
recommended that using a longer wet curing time would be helpful to reduce shrinkage
of fly ash concrete.

2) Water content has a significant effect on drying shrinkage strain of concrete. The higher
the water content, the more the concrete tends to shrink. However, no clear trend can be
seen on the effects of water to cementitious materials ratio on shrinkage of concrete.

3) For the four concrete mixtures with Georgia granite aggregate, shrinkage strain is slightly
lower than the four corresponding concrete mixtures with Miami Oolite limestone
aggregate. Lightweight aggregate concrete shrinks more than normal weight aggregate
concrete. This might be explained by their difference in elastic modulus. The concrete
with a higher elastic modulus would have a stronger resistance to the movement caused
by shrinkage of cement paste.

4) For the concretes tested, there appeared to be a relationship between the compressive
strength ( f,) at the age when shrinkage test was started and the shrinkage strain (sh ) at
91 days as follows:

-0.0001 '
sh = 0.0005 -. e00
sh
Where f is in unit of psi.
5) For the concretes tested, there appeared to be a relationship between elastic modulus (Ec)
at the age when shrinkage test was started and the shrinkage strain (sh) at 91 days as
follows:

-2x107. .E
Eh = 0.0007 e 2 10 E

Where E, is in unit ofpsi.
6) According to the shrinkage test results from this study, the C.E.B-F.I.P model (as shown
in Equation 6-6) appeared to give better prediction than the ACI 209 model (as shown in
Equation 6-3). Using ACI 209 model may result in over-estimation of the ultimate
shrinkage strain.

7) For the concrete investigated in this study, the ultimate shrinkage strain ranged from
1.93 x 104 to 3.64x 104 for the concretes with Miami Oolite limestone aggregate; from
2.18x10-4 to 2.83x10-4 for the concretes with Georgia granite aggregate; and from
3.49x10-4 to 4.22x10-4 for the concretes with Stalite lightweight aggregate concrete.









8.2.3 Creep Characteristics of Concretes Investigated


1) Curing condition has some effects on creep of fly ash concrete and lightweight aggregate
concrete, while its effect on slag concrete is very small.

2) For the stress levels used (40 and 50% of compressive strength), the measured creep
strain and instantaneous strain were linearly proportional to the stress applied. Thus, the
computed creep coefficients were not affected by the stress level in this study.

3) Water to cementitious materials ratio has some effects on creep behavior of concrete. The
higher the water to cementitious materials ratio, the more the concrete creeps.

4) For the concrete with identical water to cementitious materials ratio, the higher the air
content of fresh concrete, the more the concrete creeps.

5) The concretes with granite aggregate creeps slightly higher than the concretes with
Miami Oolite limestone aggregate and lightweight aggregate under the same stress level.
However, due to the much lower elastic modulus of lightweight aggregate concrete, the
creep coefficient of lightweight aggregate concrete is much lower than that of normal
weight aggregate concrete. Due to the higher elastic modulus of granite aggregate
concrete, creep coefficient of granite concrete was much higher than that of the concretes
with Miami Oolite limestone aggregate.

6) A simple linear relationship was established between compressive strength at loading age
and creep strain at 91 days.

7) A linear relationship was also found between creep coefficient at 91 days and
compressive strength (f,), elastic modulus (Ec), and the ratio of compressive strength
and elastic modulus. The regression equation, which relates compressive strength at
loading age to creep coefficient at 91 days ((o91) is given as follows:


c91 = a fc'+ 8 (7-2)

Where a is equal to -2.03x10-4 and 3 equal to 3.042. Andf is in unit of psi.

The regression equation, which relates elastic modulus to creep coefficient at 91 days is
given as follows:

(pc91 = a Ec + (7-3)

Where a is equal to -4.55x10.7 and 3 equal to 3.725. And E, is in unit ofpsi.

The equation related creep coefficient at 91 days to the ratio of compressive strength to
elastic modulus is given as follows:










(Pc91 = a -c + P (7-4)
EC

With ac equal to -1132 and 3 equal to 3.485.

Among these regression equations, Equation 7-2 gave the best prediction.

8) Ultimate creep coefficient of some of the concretes appeared to exceed 2.0. These
concrete mixtures included Mix-2F, Mix-3F, Mix-4F, Mix-5S, Mix-6S, Mix-7S, Mix-8S,
Mix-2GF, Mix-3GF, Mix-5GS and Mix-7GS.

9) CEB-FIP model (as shown in Equation 7-17) appeared to give better prediction on the
creep behaviors of concretes investigated in this study than ACI 209 model (as shown in
Equation7-25).

8.3 Recommendations

Based on this study, the following recommendations are given for the further study:

1) Study on effects of aggregate gradation on shrinkage and creep of concrete. Since the
gradation of aggregate has a great effect on the compressive strength of concrete
[A.M.Neville, 1996] [Larry C. Muszynski et al, 1997] and compressive strength was
found to be related to shrinkage and creep in this study, the effects of aggregate gradation
on shrinkage and creep behavior of concrete should be studied in order to have a better
understanding of this factor on shrinkage and creep of concrete.

2) Study on the optimization of mix proportion. The optimization of mix proportion should
be studied to reduce shrinkage and creep of concrete.

3) Study on the interfacial characteristics between coarse aggregate and mortar paste in
order to have a better interpretation on the effects of different aggregate types on strength
of concrete.

4) Study on theological properties of concrete under sustained load in order to have a better
understanding about the creep behavior of concrete.









APPENDIX A
MEASUREMENTS FROM STRENGTH TESTS













Table A-1 Results of compressive strength tests (psi)

No. of Age of Testing (days)
No. of7 14
mix 3 7 14


1 2 3
8018 8091 8123
4110 4195 3927
5325 5424 5118
5669 5783 5684
5351 5772 5539
6300 6402 6423
4323 4482 4166
4415 5017 4954
3019 3007 3092
1486 1411 1504
3982 3867 3807
2960 2865 3099
3746 3861 3847
2249 2205 2346


2 3
8554 8607
4680 4635
6449 6512
6762 6922
7739 6908
7316 8004
5435 5375
6202 6308
3939 3974
2310 2088
5046 4888
4612 4655
5211 5145
4178 4298


2 3
8869 9182
6032 5999
7649 7578
7208 6910
8208 8541
8481 8169
5902 5886
6967 6971
5174 5194
2860 3201
5812 5735
5778 5829
6087 6127
5182 5175


56
1
10665
6661
8479
8668
9071
9604
6773
7856
6655
4496
6887
7818
7895
7072


2
10799
6604
8400
8994
9255
9540
6812
8253
6953
4204
7001
7801
7683
6629


91
3 1
10847 11123
6648 7631
8468 9415
9325 9273
9092 9348
9593 9779
6798 6990
8249 8262
6462 7043
4236 4863
6969 7387
7943 7862
7769 8047
7176 7226


2
11302
7582
9496
9072
9615
9734
6837
8148
7092
4725
6909
7915
8090
7200


3
11376
7609
9366
9467
9406
9770
6923
8214
6750
4595
7308
8105
7986
7273










Table A-2 Normalized compressive strength development characteristics of the concrete mixtures evaluated (psi)
Age of Testing (days)
Mix Number W/C Fly ash Slag Age of T g
3 7 14 28 56 91
Mix-IF 0.24 20% 0.72 0.76 0.80 0.85/0.93* 0.96 1
Mix-2F 0.33 20% 0.54 0.61 0.79 0.86/0.87* 0.90 1
Mix-3F 0.41 20% 0.56 0.69 0.80 0.87/0.85* 0.90 1
Mix-4F 0.37 20% 0.62 0.75 0.77 0.78/0.87* 0.97 1
Mix-5S 0.33 50% 0.59 0.77 0.87 0.93/0.99* 0.97 1
Mix-6S 0.36 50% 0.66 0.80 0.89 0.94/0.95* 0.99 1
Mix-7S 0.41 70% 0.63 0.78 0.86 0.92/0.93* 0.98 1
Mix-8S 0.44 50% 0.58 0.74 0.85 0.92/0.92* 0.99 1
Mix-9LF 0.31 20% 0.44 0.57 0.74 0.85/0.84* 0.96 1
Mix-O1LS 0.39 60% 0.31 0.46 0.62 0.79/0.85* 0.91 1
Mix-2GF 0.33 20% 0.54 0.69 0.81 0.90 0.97 1
Mix-3GF 0.41 20% 0.47 0.64 0.76 0.90 0.97 1
Mix-5GS 0.33 50% 0.37 0.58 0.70 0.86 0.97 1
Mix-7GS 0.41 70% 0.31 0.59 0.72 0.91 0.93 1

o Note: Data from the replication tests.










Table A-3 Results of splitting tensile strength tests (psi)

No. of Age of Testing (days)


Mix 3


7 14 28
2 3 1 2 3 1 2 3 1
573 582 657 613 614 673 768 706 823
428 401 501 484 468 551 521 515 545
527 510 550 502 568 579 541 567 644
434 459 604 440 517 581 455 663 678
429 405 567 557 599 724 507 677 757
523 580 633 586 589 616 755 575 696
415 434 467 476 475 553 509 493 567
383 409 428 512 557 555 530 564 617
369 399 425 350 438 470 460 416 472
203 222 316 295 253 366 351 376 413
340 366 425 429 408 518 446 502 541
288 276 433 411 417 442 522 422 521
410 372 381 391 456 507 509 494 563
258 245 363 353 371 411 418 460 540


56 91
2 3 1 2 3 1 2 3
794 770 833 826 844 863 834 851
542 539 650 596 617 675 645 658
620 608 678 673 671 740 722 731
684 647 776 737 764 796 748 766
615 697 716 704 713 748 772 695
658 663 711 654 707 728 708 719
604 473 489 657 625 572 602 616
603 681 702 691 686 696 709 704
486 512 563 549 542 579 601 552
404 400 433 401 420 444 433 414
557 535 557 550 539 585 606 595
508 547 516 646 611 617 646 684
564 553 621 600 578 652 642 659
582 515 566 623 607 555 584 593


1F
2F
3F
4F
5S
6S
7S
8S
9LF
10LS
2GF
3GF
5GS
7GS










Table A-4 Normalized Splitting tensile strength development characteristics of the concrete mixtures evaluated (psi)
Mix Age of Testing (days)
W/C Fly ash Slag
Number 3 7 14 28 56 91
Mix-1F 0.24 20% 0.70 0.74 0.84 0.94/0.86* 0.98 1.00
Mix-2F 0.33 20% 0.62 0.73 0.80 0.82/0.87* 0.94 1.00
Mix-3F 0.41 20% 0.70 0.74 0.77 0.850.83* 0.92 1.00
Mix-4F 0.37 20% 0.59 0.68 0.74 0.87/0.80* 0.99 1.00
Mix-5S 0.33 50% 0.60 0.78 0.86 0.93/0.92* 0.96 1.00
Mix-6S 0.36 50% 0.79 0.84 0.90 0.94/0.87* 0.96 1.00
Mix-7S 0.41 70% 0.71 0.79 0.87 0.92/0.87* 0.99 1.00
Mix-8S 0.44 50% 0.53 0.71 0.78 0.90/0.93* 0.99 1.00
Mix-9LF 0.31 20% 0.61 0.70 0.78 0.85/0.88* 0.95 1.00
Mix-O1LS 0.39 60% 0.49 0.67 0.85 0.94/0.82* 0.97 1.00
Mix-2GF 0.33 20% 0.59 0.71 0.82 0.89 0.92 1.00
Mix-3GF 0.41 20% 0.59 0.63 0.77 0.86 0.92 1.00
Mix-5GS 0.33 50% 0.43 0.65 0.71 0.81 0.91 1.00
Mix-7GS 0.41 70% 0.42 0.63 0.75 0.87 0.96 1.00

Note: Data from the replication tests










Table A-5 Results of elastic modulus tests (xl06psi)
No. of Age of Testing (days)
Mix 3 7 14 28 56 91
1 2 1 2 1 2 1 2 1 2 1 2
1F 4.71 4.77 4.92 4.94 5.20 5.25 5.37 5.43 5.56 5.52 5.57 5.59
2F 3.47 3.38 3.72 3.82 4.11 4.04 4.28 4.34 4.46 4.40 4.77 4.50
3F 4.37 4.42 4.87 4.83 5.02 5.07 5.08 5.19 5.38 5.18 5.66 5.73
4F 4.50 4.47 4.63 4.59 4.85 4.90 4.98 5.03 5.16 5.14 5.33 5.25
5S 4.11 4.11 4.53 4.78 4.86 4.89 5.06 5.12 5.19 5.26 5.23 5.22
6S 4.42 4.11 4.97 4.86 5.08 5.28 5.23 5.67 5.48 5.75 5.54 5.78
7S 3.99 3.80 4.30 4.30 4.53 4.51 4.59 4.61 4.75 4.71 4.78 4.74
8S 3.87 4.04 4.43 4.35 4.90 4.78 5.02 4.98 5.14 5.12 5.16 5.15
9LF 2.71 2.81 2.94 2.90 3.16 3.10 3.29 3.25 3.34 3.36 3.69 3.31
10LS 1.77 1.73 2.01 1.74 2.40 2.32 2.73 2.65 3.07 2.94 2.98 3.09
3GF 3.61 3.99 4.10 4.33 4.59 4.63 4.85 5.07 5.17 5.06 5.25 5.12
S 4GF 4.08 4.21 4.28 4.95 5.56 5.48 5.62 5.59 5.83 6.03 5.95 5.97
5GS 3.24 3.06 3.66 3.97 4.54 4.76 5.42 4.92 5.48 5.26 5.47 5.64
7GS 2.63 2.74 3.28 3.48 4.05 4.14 5.17 5.33 5.64 5.56 5.77 5.68









APPENDIX B
MEASURED AND CALCULATED RESULTS FROM CREEP TESTS











Table B-l Measured and calculated results from creep tests


Load
level


Age of testing (days)


Strain


Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Creep
50% Elastic
Creep
coefficient


Creep modulus 3.71E+06 3.51E+06 3.35E+06 3.16E+06 2.98E+06 2.92E+06


No. of
Mix


Curing
condition


7-day
moist cure


14-day
moist cure


3
0.001160
0.000021
0.000716
0.000430

0.60

3.44E+06
0.001310
0.000021
0.000804
0.000450

0.54

3.32E+06
0.001070
0.000014
0.000760
0.000290

0.38

3.78E+06
0.001250
0.000014
0.000350
0.000880

0.40


7
0.001240
0.000043
0.000716
0.000480

0.68

3.16E+06
0.001420
0.000043
0.000804
0.000530

0.64

3.24E+06
0.001150
0.000033
0.000760
0.000350

0.46

3.58E+06
0.001340
0.000033
0.000420
0.000880

0.48


14
0.001330
0.000076
0.000716
0.000540

0.76

3.07E+06
0.001520
0.000076
0.000804
0.000610

0.72

3.02E+06
0.001230
0.000063
0.000760
0.000400

0.53

3.44E+06
0.001420
0.000063
0.000480
0.000880

0.54


28
0.001460
0.000120
0.000716
0.000620

0.87

2.88E+06
0.001660
0.000120
0.000804
0.000700

0.84

2.84E+06
0.001340
0.000100
0.000760
0.000470

0.62

3.26E+06
0.001530
0.000100
0.000550
0.000880

0.62


56
0.001600
0.000160
0.000716
0.000720

1.00

2.65E+06
0.001840
0.000160
0.000804
0.000840

1.00

2.65E+06
0.001450
0.000140
0.000760
0.000550

0.72

3.06E+06
0.001660
0.000140
0.000640
0.000880

0.73


91
0.001700
0.000200
0.000716
0.000780

1.10

2.52E+06
0.001970
0.000200
0.000804
0.000930

1.13

2.52E+06
0.001550
0.000170
0.000760
0.000620

0.81

2.84E+06
0.001760
0.000170
0.000710
0.000880

0.81













Table B-1. Continued
Total
Shrinkage
Elastic
40% Creep


7-day
moist cure


14-day
moist cure


Creep
coefficient
Creep Modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient
Creep Modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep Modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient
Creep Modulus


0.001141
0.000051
0.000663
0.000427

0.64

2.21E+06
0.001471
0.000051
0.000803
0.000617

0.77

2.10E+06
0.001114
0.000031
0.000669
0.000414

0.62

2.45E+06
0.001385
0.000031
0.000842
0.000512

0.61


0.001313
0.000097
0.000663
0.000553

0.83

1.98E+06
0.001614
0.000097
0.000803
0.000714

0.89

1.97E+06
0.001244
0.000069
0.000669
0.000506

0.76

2.28E+06
0.001557
0.000069
0.000842
0.000646

0.77


0.0015
0.000154
0.000663
0.000683

1.16

1.80E+06
0.001811
0.000154
0.000803
0.000854

1.07

1.80E+06
0.00139
0.000112
0.000669
0.000609

0.91

2.09E+06
0.00176
0.000112
0.000842
0.000806

0.96


0.001724
0.000210
0.000663
0.000851

1.28

1.61E+06
0.002057
0.000210
0.000803
0.001044

1.30

1.59E+06
0.001601
0.000173
0.000669
0.000759

1.13

1.85E+06
0.001972
0.000173
0.000842
0.000957

1.14


0.001961
0.000261
0.000663
0.001037

1.56

1.46E+06
0.002306
0.000261
0.000803
0.001242

1.55

1.42E+06
0.001834
0.000233
0.000669
0.000932

1.39

1.66E+06
0.002232
0.000233
0.000842
0.001157

1.37


0.002115
0.000286
0.000663
0.001166

1.76

1.37E+06
0.002471
0.000286
0.000803
0.001382

1.72

1.32E+06
0.001955
0.000258
0.000669
0.001028

1.54

1.55E+06
0.002398
0.000258
0.000842
0.001298

1.54


2.45E+06 2.23E+06 2.02E+06 1.85E+06 1.66E+06 1.55E+06













Table B-1. Continued


Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient
Creep modulus


0.001032
0.000040
0.000609
0.000383

0.61

3.05E+06
0.001221
0.000040
0.000751
0.000430

0.57

3.20E+06
0.000957
0.000021
0.000633
0.000303

0.48

3.52E+06
0.001254
0.000021
0.000776
0.000457

0.59


0.001165
0.000073
0.000609
0.000483

0.77

2.77E+06
0.00139
0.000073
0.000751
0.000566

0.75

2.87E+06
0.001093
0.000047
0.000633
0.000413

0.65

3.15E+06
0.001389
0.000047
0.000776
0.000566

0.73


0.001318
0.000124
0.000609
0.000585

0.93

2.53E+06
0.001575
0.000124
0.000751
0.000700

0.93

2.61E+06
0.001217
0.000087
0.000633
0.000497

0.79

2.92E+06
0.001537
0.000087
0.000776
0.000674

0.87


0.001477
0.000177
0.000609
0.000691

1.10

2.33E+06
0.001764
0.000177
0.000751
0.000836

1.11

2.38E+06
0.001381
0.000137
0.000633
0.000611

0.97

2.76E+06
0.001700
0.000137
0.000776
0.000787

1.01


0.001669
0.000221
0.000609
0.000839

1.33

2.09E+06
0.00199
0.000221
0.000751
0.001018

1.36

2.14E+06
0.001557
0.000182
0.000633
0.000742

1.17

2.41E+06
0.001890
0.000182
0.000776
0.000932

1.20


0.001796
0.000248
0.000609
0.000939

1.49

1.96E+06
0.002132
0.000248
0.000751
0.001133

1.51

2.01E+06
0.001686
0.000217
0.000633
0.000836

1.32

2.27E+06
0.002023
0.000217
0.000776
0.001030

1.33


3.34E+06 3.07E+06 2.84E+06 2.72E+06 2.41E+06 2.27E+06


7-day
moist cure


14-day
moist cure













Table B-1. Continued


Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient


Creep modulus 3.90E+06 2.68E+06 2.47E+06 2.30E+06 2.09E+06 1.98E+06


7-day
moist cure


14-day
moist cure


0.001060
0.000037
0.000600
0.000420

0.71

2.95E+06
0.001400
0.000037
0.000703
0.00066

0.94

2.79E+06
0.001078
0.000021
0.000571
0.000486

0.85

3.90E+06
0.001208
0.000021
0.000702
0.000485

0.69


0.001200
0.000073
0.000600
0.000530

0.89

2.68E+06
0.001523
0.000073
0.000703
0.000747

1.06

2.52E+06
0.001166
0.000042
0.000571
0.000553

0.97

2.68E+06
0.001361
0.000042
0.000702
0.000617

0.88


0.001340
0.000120
0.000600
0.000630

1.05

2.47E+06
0.001642
0.000120
0.000703
0.000819

1.17

2.32E+06
0.001259
0.000080
0.000571
0.000608

1.06

2.47E+06
0.001518
0.000080
0.000702
0.000736

1.05


0.001510
0.000170
0.000600
0.000740

1.24

2.28E+06
0.001804
0.000170
0.000703
0.000931

1.32

2.13E+06
0.001386
0.000132
0.000571
0.000683

1.20

2.31E+06
0.001699
0.000132
0.000702
0.000865

1.23


0.001680
0.000230
0.000600
0.000850

1.42

2.09E+06
0.001984
0.000230
0.000703
0.001051

1.50

1.96E+06
0.001543
0.000186
0.000571
0.000786

1.38

2.09E+06
0.001886
0.000186
0.000702
0.000998

1.42


0.001810
0.000270
0.000600
0.000940

1.57

1.98E+06
0.002120
0.000270
0.000703
0.001147

1.63

1.85E+06
0.001654
0.000223
0.000571
0.000860

1.51

1.98E+06
0.002020
0.000223
0.000702
0.001095

1.56













Table B-1. Continued
Total
Shrinkage
Elastic
40% Creep


7-day
moist cure


14-day
moist cure


Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep


Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient


0.001168
0.000044
0.000669
0.000455

0.409

2.99E+06
0.001455
0.000044
0.000846
0.000565


0.67

2.99E+06
0.001222
0.000043
0.000718
0.000461


0.64


3.00E+06
0.001464
0.000043
0.000889
0.000532


0.62


2.79E+06 2.60E+06 2.38E+06 2.19E+06 2.11E+06


0.001299
0.000088
0.000669
0.000542

0.580

2.69E+06
0.00162
0.000088
0.000846
0.000686


0.81

2.69E+06
0.001323
0.000074
0.000718
0.000531


0.74


2.79E+06
0.001596
0.000074
0.000889
0.000633


0.74


0.001423
0.000130
0.000669
0.000624

0.683

2.49E+06
0.001783
0.000130
0.000846
0.000807


0.95

2.49E+06
0.001439
0.000110
0.000718
0.000611


0.85


2.60E+06
0.001747
0.000110
0.000889
0.000748


0.87


0.001587
0.000170
0.000669
0.000748

1.101

2.28E+06
0.001977
0.000170
0.000846
0.000961


1.14

2.28E+06
0.001594
0.000149
0.000718
0.000727

1.01

2.38E+06
0.001937
0.000149
0.000889
0.000899


1.04


0.001744
0.000201
0.000669
0.000874

1.320

2.09E+06
0.002175
0.000201
0.000846
0.001128


1.33

2.09E+06
0.001747
0.000178
0.000718
0.000851


1.19


2.19E+06
0.002118
0.000178
0.000889
0.001051


1.22


0.00184
0.000216
0.000669
0.000955

1.476

1.98E+06
0.002299
0.000216
0.000846
0.001237


1.46

1.98E+06
0.001834
0.000193
0.000718
0.000923


1.29


2.11E+06
0.002212
0.000193
0.000889
0.001130


1.31


Creep modulus 2.99E+06













Table B-1. Continued
Total
Shrinkage
Elastic
40% Creep


7-day
moist cure


14-day
moist cure


Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep


Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient


0.000975
0.000042
0.000670
0.000263

0.39

3.58E+06
0.001194
0.000042
0.000837
0.000325


0.41

3.54E+06
0.001037
0.000038
0.000692
0.000307


0.43


3.70E+06
0.001263
0.000038
0.000854
0.000371


0.44


3.35E+06 3.12E+06 2.85E+06 2.51E+06 2.10E+06


0.001105
0.000082
0.000670
0.000353

0.54

3.22E+06
0.001391
0.000082
0.000837
0.000472


0.54

3.15E+06
0.001164
0.000076
0.000692
0.000396


0.57


3.40E+06
0.001467
0.000076
0.000854
0.000537


0.57


0.001255
0.000123
0.000670
0.000462

0.70

2.91E+06
0.001550
0.000123
0.000837
0.000570


0.69

2.89E+06
0.001291
0.000114
0.000692
0.000485


0.71


3.15E+06
0.001567
0.000114
0.000854
0.000599


0.70


0.001405
0.000157
0.000670
0.000588

0.90

2.65E+06
0.001707
0.000157
0.000837
0.000713


0.87

2.62E+06
0.001448
0.000141
0.000692
0.000615


0.89


2.87E+06
0.001727
0.000141
0.000854
0.000732


0.87


0.001600
0.000183
0.000670
0.000747

1.15

2.38E+06
0.001901
0.000183
0.000837
0.000891


1.08

2.31E+06
0.001648
0.000163
0.000692
0.000793


1.11


2.56E+06
0.001941
0.000163
0.000854
0.000924


1.06


0.001758
0.000196
0.000670
0.000892

1.34

2.36E+06
0.002048
0.000196
0.000837
0.001015


1.25

2.30E+06
0.001796
0.000177
0.000692
0.000927


1.27


2.21E+06
0.002104
0.000177
0.000854
0.001073


1.21


Creep modulus 3.69E+06













Table B-1. Continued
Total
Shrinkage
Elastic
40% Creep


7-day
moist cure


14-day
moist cure


Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep


Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient


0.000907
0.000039
0.000519
0.000349

0.67

2.66E+06
0.001101
0.000039
0.000616
0.000446


0.72
2.78E+06
0.000948
0.000038
0.000546
0.000364


0.67


2.84E+06
0.001160
0.000038
0.000643
0.000479


0.74


2.52E+06 2.30E+06 2.08E+06 1.90E+06 1.82E+06


0.001094
0.000080
0.000519
0.000495

0.95

2.33E+06
0.001285
0.000080
0.000616
0.000589


0.96
2.45E+06
0.001081
0.000073
0.000546
0.000462


0.85


2.57E+06
0.001308
0.000073
0.000643
0.000592


0.92


0.001264
0.000126
0.000519
0.000619

1.19

2.11E+06
0.001486
0.000126
0.000616
0.000744


1.21
2.17E+06
0.001209
0.000111
0.000546
0.000552

1.01

2.36E+06
0.001466
0.000111
0.000643
0.000712


0.001399
0.000170
0.000519
0.00071

1.37

1.92E+06
0.001664
0.000170
0.000616
0.000878


1.43
1.98E+06
0.001384
0.000148
0.000546
0.00069


1.26


2.09E+06
0.001646
0.000148
0.000643
0.000855


1.33


0.001561
0.000202
0.000519
0.00084

1.62

1.74E+06
0.001836
0.000202
0.000616
0.001018


1.65
1.81E+06
0.001556
0.000183
0.000546
0.000827


1.51


1.89E+06
0.001821
0.000183
0.000643
0.000995


1.55


0.001656
0.000223
0.000519
0.000914

1.76

1.65E+06
0.001941
0.000223
0.000616
0.001102


1.79
1.72E+06
0.001651
0.000204
0.000546
0.000901


1.65


1.79E+06
0.001921
0.000204
0.000643
0.001074


1.67


Creep modulus 2.78E+06













Table B-1. Continued


Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep


Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient


2.53E+06 2.34E+06 2.14E+06 1.93E+06 1.78E+06


7-day
moist cure


14-day
moist cure


0.001131
0.000073
0.000614
0.000443

0.72

2.71E+06
0.001296
0.000073
0.000722
0.000500


0.69

2.56E+06
0.001140
0.000050
0.000654
0.000436


0.67


2.92E+06
0.001374
0.000050
0.000831
0.000493


0.59


0.001263
0.000123
0.000614
0.000526

0.86

2.53E+06
0.001438
0.000123
0.000722
0.000592


0.82

2.38E+06
0.001262
0.000098
0.000654
0.000510


0.78


2.68E+06
0.001524
0.000098
0.000831
0.000596


0.72


0.001409
0.000161
0.000614
0.000633

1.03

2.34E+06
0.001606
0.000161
0.000722
0.000722


1.00

2.17E+06
0.001394
0.000136
0.000654
0.000604


0.92


2.51E+06
0.001677
0.000136
0.000831
0.000710


0.85


0.000157
0.000194
0.000614
0.000761

1.24

2.04E+06
0.001821
0.000194
0.000722
0.000904


1.25

1.97E+04
0.001549
0.000169
0.000654
0.000726

1.11

2.26E+06
0.001881
0.000169
0.000831
0.000881


1.06


0.001762
0.000228
0.000614
0.000920

1.50

1.82E+06
0.002048
0.000228
0.000722
0.001098


1.52

1.77E+06
0.001733
0.000202
0.000654
0.000877


1.34


2.02E+06
0.002118
0.000202
0.000831
0.001084


1.30


0.001914
0.000250
0.000614
0.001050

1.71

1.68E+06
0.002227
0.000250
0.000722
0.001254


1.74

1.63E+06
0.001889
0.000230
0.000654
0.001004


1.53


1.87E+06
0.002294
0.000230
0.000831
0.001233


1.48


Creep modulus 2.71E+06













Table B-1. Continued


7-day
moist cure


9LF


14-day
moist cure


Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep


Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient


2.08E+06 1.98E+06 1.88E+06 1.79E+06 1.72E+06


0.001118
0.000049
0.000626
0.000443

0.71

1.99E+06
0.001337
0.000049
0.000767
0.000521


0.68

1.92E+06
0.001169
0.000046
0.000677
0.000447


0.66


2.29E+06
0.001297
0.000046
0.000777
0.000474


0.61


0.001231
0.000096
0.000626
0.000510

0.82

1.85E+06
0.001487
0.000096
0.000767
0.000624


0.81

1.81E+06
0.001272
0.000081
0.000677
0.000514


0.76


2.12E+06
0.001433
0.000081
0.000777
0.000576


0.74


0.001380
0.000162
0.000626
0.000592

0.95

1.74E+06
0.001642
0.000162
0.000767
0.000713


0.93

1.69E+06
0.001392
0.000137
0.000677
0.000579


0.86


2.00E+06
0.001564
0.000137
0.000777
0.000651


0.84


0.001528
0.000226
0.000626
0.000677

1.08

1.62E+06
0.001811
0.000226
0.000767
0.000819


1.07

1.58E+06
0.001507
0.000189
0.000677
0.000641


0.95


1.91E+06
0.001691
0.000189
0.000777
0.000726


0.93


0.001684
0.000288
0.000626
0.000771

1.23

1.51E+06
0.001987
0.000288
0.000767
0.000932


1.22

1.47E+06
0.001633
0.000239
0.000677
0.000718


1.06


1.79E+06
0.001836
0.000239
0.000777
0.000820


1.06


0.001792
0.000322
0.000626
0.000844

1.35

1.43E+06
0.002112
0.000322
0.000767
0.001023


1.33

1.40E+06
0.001714
0.000276
0.000677
0.000762


1.13


1.72E+06
0.001940
0.000276
0.000777
0.000888


1.14


Creep modulus 2.21E+06













Table B-1. Continued


7-day
moist cure


10LS


14-day
moist cure


Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient


Creep modulus 1.67E+06 1.58E+06 1.51E+06 1.42E+06 1.33E+06 1.26E+06


0.001206
0.000070
0.000546
0.000590

1.08

1.16E+06
0.001517
0.000070
0.000721
0.000726

1.01

1.03E+06
0.000874
0.000038
0.000781
0.000276

0.62

1.67E+06
0.001169
0.000038
0.000713
0.000418

0.59


0.001314
0.000130
0.000546
0.000639

1.17

1.10E+06
0.001648
0.000130
0.000721
0.000797

1.10

0.99E+06
0.000898
0.000090
0.000898
0.000337

0.74

1.58E+06
0.001286
0.000090
0.000713
0.000482

0.68


0.001433
0.000198
0.000546
0.000690

1.26

1.04E+06
0.001780
0.000198
0.000721
0.000861

1.19

0.95E+06
0.000941
0.000152
0.001083
0.000380

0.82

1.51E+06
0.001406
0.000152
0.000713
0.000540

0.76


0.001559
0.000260
0.000546
0.000753

1.38

0.97E+06
0.001939
0.000260
0.000721
0.000958

1.33

0.90E+06
0.000997
0.000209
0.001123
0.000486

0.93

1.42E+06
0.001539
0.000209
0.000713
0.000617

0.87


0.001694
0.000319
0.000546
0.000830

1.52

0.92E+06
0.002098
0.000319
0.000721
0.001058

1.47

0.85E+06
0.001062
0.000279
0.001274
0.000501

1.05

1.33E+06
0.001694
0.000279
0.000713
0.000702

0.99


0.001789
0.000360
0.000546
0.000883

1.62

0.88E+06
0.002224
0.000360
0.000721
0.001143

1.59

0.82E+06
0.001116
0.000320
0.001377
0.000554

1.16

1.26E+06
0.001809
0.000320
0.000713
0.000776

1.09













Table B-1. Continued


2GF 14-day
moist cure


Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep


3GF 14-day
moist cure


Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient


3.19E+06 2.82E+06 2.53E+06 2.28E+06 2.14E+06


0.001023
0.000032
0.000601
0.000390

0.65

2.61E+06
0.001334
0.000032
0.000777
0.000526


0.001173
0.000061
0.000601
0.000511

0.85

2.33E+06
0.001494
0.000061
0.000777
0.000657


0.001333
0.000109
0.000601
0.000623

1.04

2.11E+06
0.001690
0.000109
0.000777
0.000804


0.001532
0.000161
0.000601
0.000769

1.28

1.89E+06
0.001992
0.000161
0.000777
0.000984


0.001750
0.000204
0.000601
0.000944

1.57

1.67E+06
0.002171
0.000204
0.000777
0.001190


0.001873
0.000229
0.000601
0.001043

1.74

1.57E+06
0.002323
0.000229
0.000777
0.001318


0.68

2.48E+06
0.000811
0.000024
0.000530
0.000257

0.48

3.69E+06
0.001043
0.000024
0.000666
0.000353


0.85

2.26E+06
0.000931
0.000047
0.000530
0.000354

0.67

3.28E+06
0.001187
0.000047
0.000666
0.000474


1.04

2.05E+06
0.001084
0.000076
0.000530
0.000479

0.90

2.88E+06
0.001362
0.000076
0.000666
0.000621


0.93


1.27

1.84E+06
0.001243
0.000113
0.000530
0.000600

1.33

2.57E+06
0.001549
0.000113
0.000666
0.000770


1.16


1.53

1.64E+06
0.001428
0.000157
0.000530
0.000741

1.40

2.29E+06
0.001747
0.000157
0.000666
0.000924


1.39


1.70

1.54E+06
0.001541
0.000183
0.000530
0.000828

1.56

2.14E+06
0.001879
0.000183
0.000666
0.001030


1.55


0.53


0.71


Creep modulus 3.56E+06













Table B-1. Continued


5GS 14-day
moist cure


Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep


7GS 14-day
moist cure


Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
40% Creep
Creep
coefficient
Creep modulus
Total
Shrinkage
Elastic
50% Creep
Creep
coefficient


2.57E+06 2.33E+06 2.10E+06 1.90E+06 1.84E+06


0.001024
0.000039
0.000556
0.000429

0.77

2.87E+06
0.001261
0.000039
0.000703
0.000519


0.001163
0.000064
0.000556
0.000543

0.98

2.57E+06
0.001427
0.000064
0.000703
0.000660


0.001296
0.000104
0.000556
0.000636

1.14

2.35E+06
0.001594
0.000104
0.000703
0.000787


0.001454
0.000140
0.000556
0.000758

1.36

2.13E+06
0.001783
0.000140
0.000703
0.000940


0.001615
0.000168
0.000556
0.000891

1.60

1.94E+06
0.001977
0.000168
0.000703
0.001106


0.001690
0.000184
0.000556
0.000950

1.71

1.86E+06
0.002084
0.000184
0.000703
0.001197


0.74

2.85E+06
0.000953
0.000043
0.000517
0.000393

0.76

2.91E+06
0.001208
0.000043
0.000652
0.000512


0.94

2.55E+06
0.001078
0.000074
0.000517
0.000487

0.94

2.64E+06
0.001361
0.000074
0.000652
0.000634


1.12

2.35E+06
0.001213
0.000100
0.000517
0.000597

1.15

2.38E+06
0.001517
0.000100
0.000652
0.000764


1.17


1.34

2.13E+06
0.001383
0.000131
0.000517
0.000736

1.42

2.11E+06
0.001708
0.000131
0.000652
0.000924


1.42


1.57

1.94E+06
0.001551
0.000162
0.000517
0.000872

1.69

1.90E+06
0.001899
0.000162
0.000652
0.001084


1.66


1.70

1.84E+06
0.001627
0.000181
0.000517
0.000929

1.80

1.83E+06
0.001977
0.000181
0.000652
0.001143


1.75


0.79


0.97


Creep modulus 2.84E+06









LIST OF REFERENCES


AASHTO, 2001. AASHTO LRFD Bridge Construction Specifications-2001 Interim Revisions.
American Association of State Highway and Transportation Officials, Washington, D.C.

ACI Committee 209, 1993. Prediction of Creep, Shrinkage, and Temperature Effects in Concrete
Structures (ACI 209R-92). ACI Manual of Concrete Practice, American Concrete Institute,
Detroit, MI, Part 1, pp.47.

ACI 318-83, 1983. Building Code Requirements for reinforced concrete. American Concrete
Institute, Detroit, Michigan, November 1983.

Acker Paul, Ulm Franz-Josef, 2001. Creep and Shrinkage of Concrete: Physical Origins and
Practical Measurements. Nuclear Engineering and Design 203, pp.143-158.

Aitcin, P-C. and Mehta, P. K. 1990. Effect of coarse aggregate characteristics on mechanical
properties of high strength concrete. ACI Materials Journal, Mar-Apr 1990, Vol. 87, No. 2,
pp 103-107.

Alexander, M. G.and Addis, B. J., 1992. Properties of High Strength Concrete Influenced by
Aggregates and Interfacial Bond. Bond in Concrete: From Research to Practice.
Proceedings of the CEB International Conference held at Riga Technical University, Riga,
Latvia, Oct. 15-17, Vol.2, Topics 3-7, pp.4-19 to 4-26.

Aykut Cetin and Ramon L. Carrasquillo, 1998. High-Performance Concrete: Influence of Coarse
Aggregates on Mechanical Properties. Materials Journal, Vol.95, Issue 3, May 1, 1998.

Baalbaki, W., Benmokrane, B., Chaallal, O., and Aitcin, P-C., 1991. Influence of coarse
aggregate on elastic properties of high performance concrete. ACI Materials Journal, Sep-
Oct 1991, Vol. 88, No. 5, pp 499-503.

Ba2ant, Z.P., Hauggaard A.B., Baweja S., Ulm Franz-Josef., 1997. Microprestress-Solidification
Theory for Concrete Creep I: Aging and Drying Effects. Journal of Engineering
Mechanics, Vol. 123, No. 11, November 1997, pp. 1188-1194.

Ba2ant, Z.P., 2001. Prediction of concrete creep and shrinkage: past, present and future. Nuclear
Engineering and Design, 203 (2001), pp.27-38.

Beshr H., Almusallam A.A. and Maslehuddin M., 2003. Effect of coarse aggregate quality on the
mechanical properties of high strength concrete. Construction and Building Materials,
Volume 17, Number 2, March 2003, pp. 97-103(7).

Bisschop, J. and Van Mier, J.G.M., 2000. Effect of Aggregates on Drying Shrinkage Micro-
cracking in Cement-based Materials. UEF conference, Mt-Tremblant, Canada, August,
2000, (Con. Sc. Techn).









Branson, Dan E. and Christiason, M.L.. Time Dependent Concrete Properties Related to
Designing-strength and Elasticity properties, Creep and Shrinkage, Designing for Effects
of Creep, Shrinkage and Temperature in Concrete Structures. ACI, Publication SP-27,
pp.257-278.

Branson, D.E.; Meyers, B.L.; and Kripanarayanan, K.M, 1970. Loss of Prestress, Camber, and
Deflection of Noncomposite and Composite Structures Using Different Weight Concretes.
Final Report No. 70-6, Iowa Highway Commission, Aug. 1970, Pp 1-229.

Branson, D.E.; and Christiason, M.L., 1971. Time Dependent Concrete Properties Related to
Design-Strength and Elastic Properties, Creep and Shrinkage. Symposium on Creep,
Shrinkage, and Temperature Effects, SP-27-13, American Concrete Institute, Detroit 1971,
PP.257-277.

Carino, N.J., and H.S.Lew, 1982. Re-examination of the Relation between Splitting Tensile and
Compressive Strength of Normal Weight Concrete. Journal of American Concrete
Institute, Vol.79, No.3, May-June 1982, pp.214-219.

CEB-FIP, 1990. Model Code for Concrete Structures, first draft, Bulletin d' information No. 195.
Comite-Euro-International Du Beton-Federation Internationale De La Precontrainte, Paris,
1990.

Chi, J.M., Huang, R., Yang, C.C., Chang, J.J., 2003. Effect of aggregate properties on the
strength and stiffness of lightweight concrete. Cement & Concrete Composites, 25 (2003),
pp.197-205.

Collins, T. M., 1989. Proportioning High-Strength Concrete to Control Creep and Shrinkage.
ACI Materials Journal, Nov-Dec, Vol. 86, No. 6, pp.576-580.

Collins, T. M., 1989. Proportioning high strength concrete to control creep and shrinkage. ACI
Materials Journal, Nov-Dec 1989, Vol. 86, No. 6, pp 576-580.

Cristescu, N.D, Hunsche, U., 1998. Time Effects in Rock Mechanics. John Wiley & Sons, ISBN
0471955175, 1998.

Cristescu, N.D, 1989. Rock Rheology. Kluwer Academic Publishers, ISBN 90-247-3660-9,
1989.

Ezeldin, A. S. and Aitcin, P-C. 1991. Effect of coarse aggregate on the behavior of normal and
high strength concretes. Cement, Concrete and Aggregates, Winter 1991, Vol. 13, No. 2,
pp 121-124.

FDOT, 2002. Structural Design Guidelines for Load and Resistance Factor Design. Structural
Design Office, Tallahassee, Florida

FHWA, 1994. An Analysis of Transfer and Development Lengths for Pre-tensioned Concrete
Structures. Report No. FHWA-RD-94-049, December 1994.









Gesogolu Mehmet, Zturan Turan*, Gineyisi Erhan, 2004. Shrinkage cracking of lightweight
concrete made with cold-bonded fly ash aggregates. Cement and Concrete Research 34
(2004), pp. 1121-1130.

Giaccio, G., Rocco, C., Violini, D., Zappitelli, J., and Zerbino, R., 1992. High strength concrete
incorporating different coarse aggregates. ACI Materials Journal, May-Jun 1992, Vol. 89,
No. 3, pp 242-246.

Hermite, R.L', 1960. Volume changes of concrete. Proc. 4th int. symp. On the Chemistry of
cement, Washington DC, pp.659-694.

Holm, Thomas. A., 2001. lightweight aggregate concrete. STP 169C, ASTM, pp.522-531.

Hua, C., Acker, P., Ehrlacher, A., 1995. Analysis and modeling of the autogenous shrinkage of
hardening cement paste-I. Modeling at macroscopic scale. Cement and Concrete Research,
Vol.25, No7 (1995), pp.1457-1468.

Jensen, H. E., 1992. State-of art report for high strength concrete shrinkage and creeping.
Doctoral Thesis, Afdelingen for Baerende Konstruktioner, Technical University of
Denmark, Lyngby, Denmark, 1992, 71 pp. (Text in Danish; Summary in English).

John M. Lybas, 1990. Reconciliation Study of Creep in Florida Concrete. Final Report,
Structural and Material Research Report No. 90-1. Department of Civil Engineering,
University of Florida, Gainesville, 1990.

Keeton, John R., Roll Frederic and Meyers, B.L.. Effects of Concrete Constituents, Environment,
and Stress on the Creep and Shrinkage of Concrete. ACI Committee 209, subcommittee 1,
Designing for Effects of Creep, Shrinkage and Temperature in Concrete Structures,
Publication SP-27, pp.1-23.

Larry C. Muszynski, James L. Lafrenz, and David H. Artman, 1997. Proportioning Concrete
Mixtures with Graded Aggregates. Publication ASCE, Jun 24, 1997.

Leming, M. L., 1990. Comparison of mechanical properties of high strength concrete made with
different raw materials. Transportation Research Record, 1990, No. 1284, pp 23-30.

Li, Jianyong, Yao, Yan, 2001. A study on creep and drying shrinkage of high performance
concrete. Cement and Concrete Research 31 (2001), pp. 1203-1206.

Lindgard, J. and Smeplass, S. 1993. High strength concrete containing silica fume-impact of
aggregate type on compressive strength and elastic modulus. Proceedings of the 4th
International Conference on the Use of Fly Ash, Silica Fume, Slag, and Natural Pozzolans
in Concrete, held May 3-8, 1992, Istanbul, Turkey; Sponsored by CANMET in
Association with the American Concrete Institute and Others; Ed. by V. M. Malhotra;
American Concrete Institute, Detroit, MI, 1993, Vol. 2, pp 1061-1074. (ACI SP-132).









M..A.Cassaro, 1967. A Study of Creep in Lightweight and Conventional Concretes. Final
Report. Department of Civil Engineering and Florida Engineering and Industrial
Experiment Station, University of Florida, Gainesville, Jan, 1967.

Mang Tia, 1989. Field and laboratory study of modulus of rupture and permeability of structural
concretes in Florida. Final Report, Florida Department of Transportation in cooperation
with U.S. Department of Transportation and Federal Highway Administration. Department
of Civil & Coastal Engineering, University of Florida, 1989.

M. A. Rashid, M. A. Mansur, and P. Paramasivam, 2002. Correlations between Mechanical
Properties of High-Strength Concrete. Materials Journal, Volume 14, Issue 3, pp. 230-238
(May/June 2002).

Mark G. Alexander, 1996. Aggregates and the Deformation Properties of Concrete. Materials
Journal, Vol.93, Issue 6, Nov 1, 1996.

Neville, A.M., 1996. Properties of Concrete (Fourth and Final Edition). John Wiley & Sons, Inc,
New York.

Neville, A.M., 1965. Properties of Concrete (First Edition). John Wiley & Sons, Inc, New York.

Neville, A.M., 1957. Non-elastic Deformations in Concrete Structures. J. New Zealand Inst. E.,
12, pp. 114-120.

Nilsen, A. U. and Aitcin, P-C., 1992. Properties of high strength concrete containing light-
normal, and heavyweight aggregate. Cement, Concrete, and Aggregates, Summer 1992,
Vol. 14, No. 1, pp 8-12.

Ozyildirim, C. 2000. Evaluation of High-Performance Concrete Pavement in Newport
News, VA. Draft Interim Report, Virginia Transportation Research Council,
Charlottesville.

Ozyildirim, C. 2001. Evaluation of High-Performance Concrete Pavement in Newport
News, VA. Preprint Paper 01-3173. 80th Annual Meeting of the Transportation
Research Board, Washington, DC

Paulson, K. A., Nilson, A. H., Hover, K. C, 1991. Long Term Deflection of High-Strength
Concrete Beams. ACI Materials Journal, Mar-Apr 1991, Vol. 88, No. 2, pp.197-206.

P. C. Aitcin and P. K. Mehta, 1990. Effect of Coarse Aggregate Characteristics on Mechanical
Properties of High-Strength Concrete. Materials Journal, Vol. 37, Issue 2, March 1, 1990.

Persson Bertil, 2001. A comparison between mechanical properties of self-compacting concrete
and the corresponding properties of normal concrete. Cement and Concrete Research, 31
(2001), pp.193 -198.









Phillieo, R.E.. Summary of Symposium on Designing for Effects of Shrinkage, Creep and
Temperature, Designing for effects of creep, shrinkage and temperature in concrete
structures. ACI, Publication SP-27, pp.247-253.

Pichett, G., 1956. Effect of aggregate on shrinkage of concrete and hypothesis concerning
shrinkage. J. Amer. Concr. Inst., 52, pp.581-590.

P. Zia, M. L. Leming, S. H. Ahmad, J. J. Schemmel, R. P. Elliott, and A. E. Naaman., 1993a.
Mechanical Behavior of High Performance Concretes, Volume 1: Summary Report.
Strategic Highway Research Program, National Research Council, Washington, D. C., xi,
98 pp. (SHRP-C-361).

P. Zia, M. L. Leming, S. H. Ahmad, J. J. Schemmel, and R. P. Elliott. 1993b. Mechanical
Behavior of High Performance Concretes, Volume 2: Production of High Performance
Concrete. Strategic Highway Research Program, National Research Council, Washington,
D. C., xi, 92 pp. (SHRP-C-362).

P. Zia, S. H. Ahmad, M. L. Leming, J. J. Schemmel, and R. P. Elliott. 1993c. Mechanical
Behavior of High Performance Concretes, Volume 3: Very Early Strength Concrete.
Strategic Highway Research Program, National Research Council, Washington, D. C., xi,
116 pp. (SHRP-C-363).

P. Zia, S. H. Ahmad, M. L. Leming, J. J. Schemmel, and R. P. Elliott. 1993d. Mechanical
Behavior of High Performance Concretes, Volume 4: High Early Strength Concrete.
Strategic Highway Research Program, National Research Council, Washington, D. C., xi,
179 pp. (SHRP-C-364).

P. Zia, S. H. Ahmad, M. L. Leming, J. J. Schemmel, and R. P. Elliott. 1993e. Mechanical
Behavior of High Performance Concretes, Volume 5: Very High Strength Concrete.
Strategic Highway Research Program, National Research Council, Washington, D. C., xi,
101 pp. (SHRP-C-365).

Reichard, T.W., 1964. Creep and drying shrinkage of lightweight and normal weight concretes.
Nat. Bur. Stand. Monograph, 74, Washington DC, March, 1964.

Roberts, John.Thomas., 1951. The Elastic Properties of Concrete and Their Effects on Design. A
Thesis for Master Degree, University of Florida, August, 1951.

Riusch, H., Kordina, K. and Hilsdorf, H., 1963. Der einfluss des mineralogischen Charakters der
Zuschlage auf das Kriechen von Beton. Deutscher Ausschuss fir Stahlbeton, No. 146,
pp.19-133.

Russell, H. G., Larson, S. C, 1989. Thirteen Years of Deformations in Water Tower Place. ACI
Structural Journal, Mar-Apr 1989, Vol. 86, No. 2, pp.182-191.

Sarkar, S. L. and Aitcin, P-C, 1990. Importance of petrological, petrographical and mineralogical
characteristics of aggregates in very high strength concrete. ASTM Special Technical
Publication, 1990, No. 1061, pp 129-144.









Schlumpf Jirg, 2004. Self-compacting concrete structures in Switzerland. Tunnelling and
Underground Space Technology, 19 (2004) 480.

Shideler, J.J., 1957. Lightweight aggregate concrete for structural use. J. Amer. Concr. Inst., 54,
pp.299-328.

Shih, T. S., Lee, G. C., and Chang, K. C.,1989. On static modulus of elasticity of normal weight
concrete. Journal of Structural Engineering, Oct 1989, Vol. 115, No. 10, pp 2579-2587.

Stock, A.F., Hannant, D.J. and Williams, R.I.T., 1979. The effect of aggregate concentration
upon the strength and modulus of elasticity of concrete. Mag. Concr. Res., 31, No. 109,
pp.225-234.

Thomas, Jeffrey J. and Jennings, Hamlin M., 2001. Chemical Aging and the Colloidal Structure
of the C-S-H Gel: Implication for Creep and Shrinkage. Creep, Shrinkage and Durability
Mechanics of Concrete and Other Quasi-brittle Materials edited by F,-J. Ulm, Z.P. Ba2ant
and F.H. Wittmann. (2001), pp.33-38.

Troxell, G.E., Raphael, J.M. and Davis, R.E., 1958. Long-time creep and shrinkage tests of plain
and reinforced concrete. Proc. ASTM., 58, pp. 1101-1120.

Wu K.-R., Chen B., Yao W., Zhang D, 2001. Effect of coarse aggregate type on mechanical
properties of high-performance concrete. Cement and Concrete Research, Volume
31, Number 10, October 2001, pp. 1421-1425(5).

Zhou, F.P., Lydon, F.D. and Barr, B.I.G., 1995. Effect of coarse aggregate on elastic modulus
and compressive strength of high performance concrete. Cement and Concrete Research,
Vol. 25, No. 1, pp.177-186.

Zia, P., Leming, M.L., Ahmad, S.H. 1991. High-Performance Concrete: A State-of-the-Art
Report. Strategic Highway Research Program, National Research Council, Washington, D.
C., (SHRP-C/FR-91-103; PB92-130087), pp.251.

Zia, P., Ahmad, S.H., Leming, M.L., Schemmel, J.J., Elliott, R.P. 1993. Mechanical Behavior of
High Performance Concretes. Volume 5: Very High Strength Concrete. Strategic Highway
Research Program, National Research Council, Washington, D. C., xi, (SHRP-C-365),
pp.101.









BIOGRAPHICAL SKETCH

Liu Yanjun, born in 1973 in China, is a civil engineer. He went to Shenyang Architectural

and Civil Engineering Institute in 1993. Four years later, he earned his bachelor's degree in civil

engineering in 1997. Then, he got scholarship from China Building Materials Academy and

worked on his Master's study in Material Science and Engineering. After three years, in 2000, he

earned his Master's degree at China Building Materials Academy in Material Science and

Engineering with minor focus on cement and concrete materials. After that, he worked for China

Building Materials Academy for 2 years. Then, he obtained full scholarship from Civil and

Coastal Engineering Department of University of Florida and involved PhD program on the

research on cement and concrete materials. At last, he achieved his PhD at the University of

Florida in 2007.


218





PAGE 1

1 STRENGTH, MODULUS OF ELASTICITY, SHRINKAGE AND CREEP OF CONCRETE By YANJUN LIU A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2007

PAGE 2

2 2007 Yanjun Liu

PAGE 3

3 To my Mom and Dad, Ren Shuzhen and Liu Yu chun, for everything they have done and are doing for their child, my daughter for her understanding and cons ideration for 6-year-long life without dads company, and my brother and sisters for their great support and encouragement.

PAGE 4

5 ACKNOWLEDGMENTS It is m y immense pleasure in thanking the pe rsons and organizations that helped me over years to bring my PhD dissertation to the final form. Firstly, great appreciation goes to the ch airman, Dr. Mang Tia, and cochairman, Dr. Reynaldo Roque for sincere encouragement and patient guidance. You are the beacons guiding me throughout my tough trek of pursuing PhD. Wi thout your help, this di ssertation can not be completed. Please let me regard you as loyal friends and great mentors. Secondly, great appreciation goes to the member s of my supervisory committee, Dr. N.D. Cristescu and Dr. Larry.C.Muszynski, for your great enlightenment and keen research assistance. Thirdly, graceful acknowledgement extends to Florida Department of Transportation (FDOT) for providing the financial s upport, testing equipment, materials that made this research possible. The Florida Department of Transpor tation personnel Messrs. Mi chael Bergin, Richard Delorenzo, Joseph Fitzgerald, and Craig Roberts ar e appreciated for their help with the entire process of fabricating test samples. Fourthly, I like to thank all my colleagues in the materials section of Civil & Coastal Engineering Department. Danny Br own, Chuck Broward, Nard Hube rt and George A. Lopp are acknowledged for their assistance in this study. In addition, special thanks are given to th e Florida Rock Industries Company for donating slag, Boral Materials Company for donating fly ash, and W. R. Grace & Co for donating chemical admixtures, and Carolina Stalite Comp any for donating lightweight aggregate. Without your sincere help, this study could not be completed on time. At last, my sincere thanks go to my pare nts for their persiste nt encouragement and unconditional love, which motivated me to comp lete my study. I believe the fulfillment of my study will bring you joy, which is the only thing you need from your child.

PAGE 5

6 TABLE OF CONTENTS page ACKNOWLEDGMENTS...............................................................................................................5 LIST OF TABLES................................................................................................................. ........10 LIST OF FIGURES.......................................................................................................................12 ABSTRACT...................................................................................................................................17 CHAP TER 1 INTRODUCTION..................................................................................................................19 1.1 Background and Research Needs..................................................................................... 19 1.2 Hypothesis........................................................................................................................21 1.3 Objectives of Study........................................................................................................ ...21 2 LITERATURE REVIEW.......................................................................................................23 2.1 Introduction............................................................................................................... ........23 2.2 Strength of Concrete.........................................................................................................23 2.2.1 Significance of Studying Strength of Concrete......................................................23 2.2.2 Effect of Coarse Aggreg ate on Strength of Concrete ............................................. 24 2.2.3 Prediction of Strength of Concrete.........................................................................26 2.3 Elastic Modulus of Concrete............................................................................................ 27 2.3.1 Definition and Determination of Elastic Modulus of Concrete.............................. 27 2.3.2 Significance of Studying Elastic Modulus of Concrete ......................................... 28 2.3.3 Effect of Coarse Aggregate on Elastic Modulus of Concrete ................................ 29 2.3.4 Models for Predicting Elas tic Modulus of Concrete .............................................. 32 2.4 Shrinkage Behavior of Concrete.......................................................................................35 2.4.1 Origin of Shrinkage of Concrete............................................................................ 35 2.4.2 Significance of Studying Shrinkage of Concrete...................................................36 2.4.3 Effect of Raw Materials on Shrinkage of Concrete................................................ 37 2.4.3.1 Effect of aggregate content on shrinkage behavior of concrete ................... 37 2.4.3.2 Effects of coarse aggregate type on concrete shrinkage ............................... 39 2.4.3.3 Effects of size and shape of coarse aggregate on concrete shrinkage .......... 40 2.4.3.4 Effect of other factors on shrinkage behaviors of concrete .......................... 41 2.4.4 Models to Predict Concrete Shrinkage................................................................... 42 2.4.4.1 CEB-FIP Model for shrinkage strain prediction.......................................... 43 2.4.4.2 Prediction model recommended by ACI-209 Report [1992].......................45 2.5 Creep of Concrete.............................................................................................................46 2.5.1 Rheology of Materials and Definition of Creep of Concrete.................................46 2.5.2 Significance of Studying Creep Behavior of Concrete .......................................... 48 2.5.3 Effect of Aggregate on Creep of Hardened Concrete............................................ 49 2.5.4 Prediction Models and Their Li m itations of Concrete Creep................................ 51

PAGE 6

7 2.5.4.1 C.E.B-F.I.P Model Code..............................................................................53 2.5.4.2 Model of ACI 209........................................................................................55 3 MATERIALS AND EXPERIMENTAL PROGRAMS......................................................... 58 3.1 Introduction............................................................................................................... ........58 3.2 Concrete Mixtures Evaluated........................................................................................... 58 3.2.1 Mix Proportion of Concrete.................................................................................... 58 3.2.2 Mix Ingredients......................................................................................................59 3.3 Fabrication of Concrete Specimens..................................................................................60 3.3.1 The Procedure to Mix Concrete............................................................................. 60 3.3.2 The Procedure to Fabricate Specimens.................................................................. 66 3.4 Curing Conditions for Concrete Specimens..................................................................... 66 3.5 Tests on Fresh Concrete.................................................................................................... 67 3.6 Tests on Hardened Concrete............................................................................................. 69 3.6.1 Compressive Strength Test..................................................................................... 69 3.6.2 Splitting Tensile Strength Test (or Brazilian Test) ................................................. 70 3.6.3 Elastic Modulus Test..............................................................................................72 3.6.4 Shrinkage Test........................................................................................................73 4 CREEP TEST APPARATUS DESI GN AND TESTING PROCEDURE ............................. 76 4.1 Introduction............................................................................................................... ........76 4.2 Creep Test Apparatus.......................................................................................................76 4.2.1 Design Requirements of Creep Test Apparatus.....................................................76 4.2.2 Design of Creep Apparatus.................................................................................... 77 4.2.2.1 The determination of the maximum capacity of the creep Apparatus ......... 77 4.2.2.2 The design of springs................................................................................... 77 4.2.2.3 Design of header plate..................................................................................79 4.2.2.4 Determination of the size of steel rod.......................................................... 81 4.2.2.5 Stress relaxation due to the deflec tion of header plate and creep of concrete.................................................................................................................81 4.3 Design of Gage-Point Positioning Guide.........................................................................82 4.4 Design of Alignment Frame............................................................................................. 82 4.5 Mechanical Strain Gauge.................................................................................................. 85 4.6 Other Details on Creep Apparatus....................................................................................85 4.7 Creep Testing Procedure...................................................................................................86 4.8 Summary on the Performance of the Creep Apparatus.................................................... 93 5 ANALYSIS OF STRENGTH TEST RESULTS.................................................................... 95 5.1 Introduction............................................................................................................... ........95 5.2 Results and Analysis of Co m pressive Strength Tests....................................................... 95 5.2.1 Effects of Water to Cement Rati o and W ater Content on Compressive Strength....................................................................................................................... .95 5.2.2 Effects of Aggregate Types on Compressive Strength........................................... 98 5.2.3 Effects of Fly Ash and Slag on Co m pressive Strength of Concrete..................... 102

PAGE 7

8 5.2.4 Prediction of Compressive Strength Development.............................................. 103 5.3 Analysis of Splitting Tensile Strength Test Results....................................................... 105 5.3.1 Effects of Water to Cement Ra tio on Splitting Tensile S trength......................... 105 5.3.2 Effects of Coarse Aggregate T ype on Splitting Tensile S trength........................ 105 5.3.3 Effects of Fly Ash and Slag on Split ting Tensile Strength of Concrete ...............113 5.4 Relationship between Compressive Stre ngth and Splitting Tensile S trength................ 114 5.5 Analysis of Elastic Modulus Test Results...................................................................... 117 5.6 Relationship between Compressive Strength and Elastic Modulus ............................... 120 5.7 Summary of Findings.....................................................................................................122 6 ANALYSIS OF SHRINKAGE TEST RESULTS ...............................................................127 6.1 Introduction............................................................................................................... ......127 6.2 Results and Analysis of Shrinkage Tests........................................................................ 127 6.2.1 Effects of Curing Conditions on Shrinkage Behavior of Concrete ...................... 127 6.2.2 Effects of Mineral Additiv es o n Shrinkage Behavior.......................................... 129 6.2.3 Effects of Water Content on Shrinkage Behavior................................................ 130 6.2.4 Effects of Aggregate Types on Shrinkage Behavior............................................ 131 6.2.5 Relationship between Compressive Strength and Shrinkage Strain..................... 133 6.2.6 Relationship between Elastic Modulus and Shrinkage Strain ..............................135 6.3 Evaluation on Shrinkage Prediction Models.................................................................. 137 6.3.1 ACI-209 model..................................................................................................... 137 6.3.2 CEB-FIP Model....................................................................................................138 6.4 Prediction of Ultimat e Shrinkage Strain ......................................................................... 140 6.4.1 Least Square Method of Curve-fitting..................................................................141 6.4.2 Evaluation Methods on the Goodness of Fit........................................................142 6.4.3 Predicted Results..................................................................................................145 6.5 Summary of Findings.....................................................................................................146 7 ANALYSIS OF CREEP TEST RESULTS ..........................................................................148 7.1 Introduction............................................................................................................... ......148 7.2 Analysis of Creep Test Results.......................................................................................148 7.2.1 Effects of Curing Conditions on Creep Behavior of Concrete ............................. 148 7.2.2 Effects of Loading Condition on Creep Behavior of Concrete............................151 7.2.3 Effects of Aggregate Types on Creep Behavior of Concrete............................... 153 7.2.5 Effects of Water to Cement Rati o and Air Content on Creep Strain .................... 156 7.2.6 Relationship between Compressive Strength and Creep Strain........................... 157 7.3 Creep Coefficient............................................................................................................163 7.3.1 Effects of Loading Conditions on Creep Coefficient........................................... 163 7.3.2 Effects of Curing Conditions on Creep Coefficient............................................. 163 7.3.3 Effects of Water Content on Creep Coefficient................................................... 165 7.3.4 Effects of Compressive Strength at Loading Age on Creep Coefficient .............. 166 7.3.5 Relationship between Elastic Modulus at Loading Age and Creep Coefficient .. 169 7.3.6 Effects of Coarse Aggregat e Type on Creep Coefficient ..................................... 171 7.4 Creep Modulus................................................................................................................172 7.5 Prediction of Ultimate Creep Strain............................................................................... 174

PAGE 8

9 7.6 Evaluation on Creep Prediction Models......................................................................... 175 7.7 Summary of Findings.....................................................................................................186 8 CONCLUSIONS AND RECOMMENDATIONS ...............................................................188 8.1 Design of Creep Apparatus............................................................................................. 188 8.2 Findings from This Study............................................................................................... 188 8.2.1 Strength and Elastic Modulus............................................................................... 188 8.2.2 Shrinkage Characteristics of Concretes Investigated ........................................... 190 8.2.3 Creep Characteristics of Concretes Investigated.................................................. 191 8.3 Recommendations...........................................................................................................192 APPENDIX A MEASUREMENTS FROM STRENGTH TESTS ............................................................... 193 B MEASURED AND CALCULATED RESULTS FROM CREEP TESTS ..........................199 LIST OF REFERENCES.............................................................................................................212 BIOGRAPHICAL SKETCH.......................................................................................................218

PAGE 9

10 LIST OF TABLES Table page 3-1 Mix proportions of the 14 concrete m ixtures involved in this study................................. 61 3-2 Physical properties of Type I cement................................................................................. 62 3-3 Chemical ingredients of Type I cement............................................................................. 62 3-4 Physical and chemical properties of fly ash .......................................................................62 3-5 Physical and chemical properties of slag........................................................................... 62 3-6 Physical properties of fine aggregate .................................................................................62 3-7 Physical properties of coarse aggregates ...........................................................................62 3-8 The testing programs on fresh concrete............................................................................. 67 3-9 Properties of fresh concrete............................................................................................... 68 3-10 The testing program on hardened concrete........................................................................69 5-1 Compressive strength of the concrete m ixtures evaluated................................................. 95 5-2 Comparison of the accuracy between ACI equation and Modified ACI Equation.......... 106 5-3 Regression analysis on the prediction of com pressive strength of concrete....................107 5-4 Values of the constants, and / and the time ratio .................................................. 108 5-5 Splitting tensile strengths of th e concrete m ixtures evaluated......................................... 109 5-6 Regression analysis for relating compre ssive strength to splitting tensile strength......... 115 5-7 Elastic module of the concrete mixtures evaluated.......................................................... 117 5-8 Regression analysis using the expression recomm ended by ACI 318-89....................... 123 5-9 Regression analysis on ACI 318-95 equati on with forcing it through origin point ......... 123 5-10 Regression analysis using the expression recomm ended by ACI 318-95....................... 125 6-1 Shrinkage strains of the concrete mi xtures evaluated at various curing ages .................. 128 6-2 Regression analysis on re lationship of com pressive st rength to shrinkage strain...........135 6-3 Regression analysis on relationship of elastic modulus to shrinkage strain ....................136

PAGE 10

11 6-4 Correction factors for the ACI 209 model on shrinkage prediction ................................ 138 6-5 Regression analysis results.............................................................................................. 146 7-1 Regression analysis on relationship betw een compressive strength and creep strain ..... 160 7-2 Regression analysis on rela tionship of com pressive strength to creep coefficient.......... 167 7-3 Regression analysis on re lationship of elastic modulus to creep coefficient ................... 171 7-4 Regression analysis on relati on of creep coefficient to fc/E............................................ 171 7-5 The predicted ultimate creep strain and creep coefficient............................................... 175 7-6 Regression analysis on relati on of creep coefficient to fc/E............................................ 182 7-7 Correction factors for the ACI 209 model ....................................................................... 185 A-1 Results of compressive strength tests.............................................................................. 194 A-2 Normalized compressive strength deve lopm ent characteristics of the concrete mixtures evaluated........................................................................................................... 195 A-3 Results of splitting tensile strength tests .......................................................................... 196 A-4 Normalized Splitting tens ile strength developm ent char acteristics of the concrete mixtures evaluated........................................................................................................... 197 A-5 Results of elastic modulus tests....................................................................................... 198 B-1 Measured and calculated results from creep tests ............................................................200

PAGE 11

12 LIST OF FIGURES Figure page 2-1 Representation of the stress-strain relation for concrete.................................................... 27 2-2 Stress-strain relations for cemen t paste, aggregate and concrete ....................................... 29 2-3 Effect of coarse aggregate cont ent on the shrinkage of concrete ....................................... 37 2-4 Creep diagram of concrete material...................................................................................47 2-5 Strain-time plot of concrete under a su stained load and after release of load ...................48 3-1 Gradation of fine aggregate (Godenhead sand).................................................................63 3-2 Gradation of coarse aggreg ate (Miam i Oolite limestone).................................................. 63 3-3 Gradation of coarse a ggregate (Georgia granite) ............................................................... 64 3-4 Gradation of lightwei ght aggregate (S talite)...................................................................... 64 3-5 Compulsive Pan Mixer...................................................................................................... 65 3-6 Typical failure model of conc rete cylinder in compression test ........................................ 70 3-7 Loading configuration fo r splitting tensile test .................................................................. 71 3-8 MTS system for elastic modulus and com pressive strength test....................................... 73 3-9 Cylindrical specimen with gage point installed .................................................................74 4-1 Creep test apparatus....................................................................................................... ....78 4-2 Boundary conditions used for finite element analysis....................................................... 79 4-3 Mesh plot of Header plate analysis.................................................................................... 80 4-4 Contour plot of defl ection of header plate ......................................................................... 80 4-5 Design of Gage-point positioning guide............................................................................ 83 4-6 Gauge position guide.........................................................................................................84 4-7 Plastic cylindrical mold inside gauge position guide ......................................................... 84 4-8 Schematic of Alig nm ent Frame Design............................................................................. 87 4-9 Mechanical gauge........................................................................................................... ...88

PAGE 12

13 4-10 Positioning springs on the bottom plate............................................................................. 88 4-12 Concrete cylinder with both end surfaces ground.............................................................. 89 4-13 How to center the specimens into creep frame.................................................................. 90 4-14 How to center the hydraulic jack cylinder......................................................................... 91 4-15 Leveling the plate on the top of load cell ........................................................................... 91 5-1 Effect of water to cementitious material s ratio on com pressive strength at 28 days......... 96 5-2 Effect of water to cementitious mate rials on com pressive strength at 91 days................. 97 5-3 Effect of water content on compressive strength at 28 days.............................................. 97 5-4 Effect of water content on compressive strength at 91 days.............................................. 98 5-5 Effect of coarse aggreg ate type on com pressive strengths of Mix-2F and Mix-2GF......100 5-6 Effect of coarse aggreg ate type on com pressive strength of Mix-3F and Mix-3GF....... 100 5-7 Effect of coarse aggreg ate type on com pressive strength of Mix-5S and Mix-5GS....... 101 5-8 Effect of coarse aggreg ate type on com pressive strength of Mix-7S and Mix-7GS....... 101 5-9 Effect of fly ash and slag on com pressive strength of concrete.......................................102 5-10 Effect of water to cement ratio on splitting tensile st rength at 28 days ........................... 109 5-11 Effect of water to cement ratio on splitting tensile st rength at 91 days ........................... 110 5-12 Effect of aggregate type on splitting tensile strength of Mix-2F and Mix-2GF .............. 111 5-13 Effect of aggregate type on splitting tensile strength of Mix-3F and Mix-3GF .............. 111 5-14 Effect of aggregate type on splitting tensile strength of Mix-5S and Mix-5GS .............. 112 5-15 Effect of aggregate type on splitting tensile strength of Mix-7S and Mix-7GS .............. 112 5-16 Effect of fly ash and slag on sp litting tensile strength of concrete .................................. 114 5-17 Relationship between compressive st rength and splitting tensile strength ...................... 116 5-18 Effect of coarse aggregate type on modul us of elasticity of Mix-2F and Mix-2GF ........118 5-19 Effect of coarse aggregate type on modul us of elasticity of Mix-3F and Mix-3GF ........119 5-20 Effect of coarse aggregate type on modul us of elasticity of Mix-5S and Mix-5GS ........119

PAGE 13

14 5-21 Effect of coarse aggregate type on modul us of elasticity of Mix-7S and Mix-7GS ........120 5-22 Relationship between compressive strengt h and elastic m odulus based on ACI Code... 124 5-23 Plot of elastic modulus against w1.5fc for all curing conditions......................................124 6-1 Effect of curing condition on shrinkage st rain of concrete m ixtures at 91 days.............. 130 6-2 Effect of water content on shrinkage strain at 91 days .................................................... 131 6-3 Effect of water to cementitious materi als ratio on shrinkage strain at 91 days ...............132 6-4 Effect of coarse aggregate type on shrinkage behavior of concrete ................................ 133 6-5 Relationship between compressive strength and shrinkage strain at 91 days ..................135 6-6 Relationship between shrinkage strain at 91 days and m odulus of elasticity.................. 136 6-7 Comparison between the shrinkage strain at 91 days and the shrinkage strain calculated by ACI 209 model and C.E.B-F.I.P model ..................................................... 140 6-8 Comparison among the ultimate shrinkage strain s from curve-fitting, CEB-FIP model and ACI 209 model...............................................................................................145 7-1 Effect of curing condition on creep of concrete loaded at 40% of com pressive strength.............................................................................................................................150 7-2 Effect of curing condition on creep of concrete loaded at 50% of com pressive strength.............................................................................................................................150 7-3 Effect of stress level on creep of concrete m oist-cured for 7 days.................................. 152 7-4 Effect of stress level on creep of concrete m oist-cured for 14 days................................ 153 7-5 Effect of aggregate type on creep behavior of Mix-2F .................................................... 154 7-6 Effect of aggregate type on creep behavior of Mix-3F .................................................... 155 7-7 Effect of aggregate type on creep behavior of Mix-5S .................................................... 155 7-8 Effect of aggregate type on creep behavior of Mix-7S .................................................... 156 7-9 Effect of water to cementitious material s ratio an d air content on creep of concrete moist-cured for 7 days and loaded at 40% of compressive strength................................158 7-10 Effect of water to cementitious material s ratio an d air content on creep of concrete moist-cured for 7 days and loaded at 50% of compressive strength................................159

PAGE 14

15 7-11 Effect of water to cementitious material s ratio an d air content on creep of concrete moist-cured for 14 days and loaded at 40% of compressive strength..............................159 7-12 Effect of water to cementitious material s ratio an d air content on creep of concrete moist-cured for 14 days and loaded at 50% of compressive strength..............................160 7-13 Relationship between compressive strength and creep strain of concrete m oist-cured for 7 days..........................................................................................................................161 7-14 Relationship between compressive strength and creep strain of concrete m oist-cured for 14 days........................................................................................................................161 7-15 Relationship between compressive strength and creep strain of concrete under all curing conditions ..............................................................................................................162 7-16 Relationship of compressive strength to in stantaneous strain measured in creep test ..... 162 7-17 Effect of stress level on creep coefficient of concrete m oist-cured for 7 days................ 164 7-18 Effect of stress level on creep coefficient of concrete m oist-cured for 14 days.............. 164 7-19 Effect of curing condition on creep coefficient of concrete ............................................ 165 7-20 Effect of water content on creep coefficient at 91 days ................................................... 166 7-21 Relationship between compressive stre ngth and creep coefficient for specim ens loaded at 14 days..............................................................................................................168 7-22 Relationship between compressive stre ngth and creep coefficient for specim ens loaded at 28 days..............................................................................................................169 7-23 Relationship between compressive strength at loading age and corresponding creep coefficient at 91 days ....................................................................................................... 169 7-24 Effect of Elastic modulus at load ing age on creep coefficient at 91 days ....................... 170 7-25 Relationship between creep coefficient at 91 days and fc/E............................................ 171 7-26 Effect of coarse aggregate t ype on creep coefficient at 91 days ...................................... 172 7-27 Typical decay curve of creep modulus with time............................................................ 173 7-28 Behaviors of a Burgers Model......................................................................................... 176 7-29 Evaluation on creep prediction models............................................................................ 178 7-30 Comparison on the effectiveness of C.E.B-F.I.P model and ACI m odel........................ 180

PAGE 15

16 7-31 Comparison between the creep strain at 91 days from experimental data and the predicted creep strain using CEB-FIP model................................................................... 181 7-32 Relationship between creep strain and m echanical properties at loading age................. 182 7-33 Comparison between the ultimate creep stra in calculated by C.E.B-F.I.P model and that by curve-fitting..........................................................................................................183 7-34 Evaluation on ACI-209 model and C.E.B-F.I.P model................................................... 185

PAGE 16

17 Abstract of Dissertation Pres ented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy STRENGTH, MODULUS OF ELASTICITY, SHRINKAGE AND CREEP OF CONCRETE By Yanjun Liu December 2007 Chair: Mang Tia Cochair: Renaldo Roque Major: Civil Engineering In the application of prestres sed concrete, there are concerns on severe prestress loss caused mainly by elastic shortening, shrinkage and creep of concrete, which will result in the extreme reduction of the design capacity of prestre ssed concrete structure, or even the premature structure failure. Hence, the values of elastic modulus, ultimate shrinkage strain, and ultimate creep coefficient of concrete have to be es timated reasonably and accurately at the production stage in order to avoid loss of structural capaci ty, or even unexpected structural failure caused by prestress loss. At present, the modulus of elasticity, shrinkage and creep properties of concrete that are used in structural design are either based on the arbitrary available literature or based on the limited research of the locally available mate rials. Thus, there is a great need for a comprehensive testing and evaluation of locally available concrete mixes to determine their mechanical and physical properties so that correct values for these properties can be used in structural design. Also, there is a great need to design a simple, e ffective, practical and reliable creep apparatus to carry this massive investigation on creep behavior of concrete out. In this study, a creep test a pparatus was designed, and twenty four creep apparatus were constructed for use in performing creep tests. Th e creep apparatus was evaluated to be working

PAGE 17

18 satisfactorily. An effective creep testing pr ocedure was developed and documented. Also, a gauge point position guide was designed for insta lling gauge point on the cy lindrical mold and it was proved to be an effective t ool in preparation of specimens for creep tests. In addition, an alignment frame was designed and it was proved to be a very useful tool to ensure that the specimens can be set up in the creep apparatus vertically. In this study, 14 concrete mixtures were ev aluated, and replicate batches for ten of these mixes were also produced and evaluated. Three types of coarse aggregate, fly ash and ground blast-furnace slag were incorporated in the mi x designs in this study. Concrete specimens were fabricated and tested for their compressive stre ngth, splitting tensile st rength, elastic modulus, shrinkage and creep. This study ha s generated valuable data and determined general trends on the compressive strength, splitti ng tensile strength, elastic modulus drying shrinkage strains and creep coefficient of structural concretes investigated in this study. Most importantly, the interrelationships among compressive strength, elastic modulus and shrinkage and creep properties of concrete were found through regression analysis. These relationships make the predictions of shrinkage and creep possible with the informa tion from compressive strength and elastic modulus.

PAGE 18

19 CHAPTER 1 INTRODUCTION 1.1 Background and Research Needs Prestressed concrete structures, such as prestressed girder fo r long-span bridge, prestressed shell concrete structure for the storage of water or gas, nuclear reactor vessels and offshore oil drilling platf orms so on, are widely used in the U. S as well as other countr ies in the world. This is attributed mainly to the advantages of pr estressed concrete structure, which include1) eliminating or considerably reducing the net te nsile stresses caused by load, 2) increasing the capacity of the structure, and 3) decreasing the self-weight of concrete members. Also, prestressed concrete element is slimmer than rein forced concrete and more pleasing aesthetically. In the application of prestres sed concrete, there are concerns on severe prestress loss caused mainly by elastic shortening, shrinkage an d creep of concrete. Consequently, the design capacity of prestressed concrete structure will be extremely reduc ed, or even the structure will fail prematurely. Hence, the values of elastic modulus, ultimate shrinkage strain, and ultimate creep coefficient of concrete have to be es timated reasonably and accurately at the production stage in order to avoid loss of structural capaci ty, or even unexpected structural failure caused by prestress loss. For the sake of avoiding unexpected prestre ss loss, the strict requirements on shrinkage and creep properties of the concrete used for pres tressed concrete structures have been specified by ACI Code as well as other Specifications. For example, the AASHTO LRFD Bridge Construction Specifications-2001 Interim Revisi ons [AASHTO, 2001] specifies that, for the design of continuous prestressed concrete I-girder superstructures, the ultimate creep coefficient should be 2.0 and the ultimate shrinkage strain will take the value of 0.0004, in accordance with the recommendation of ACI 209. The Specification also states that, when specific data are not

PAGE 19

20 available, estimates of shrinkage and creep may be made using the provisions of CEB-FIP model or ACI 209 model. The creep behavior of concrete has been the focus of engineers attention and may still be the engineers concentration for decades to come because of the volatility of the creep property of concrete. Over the years, many attempts have been tried to develop the general constitutive equation for the description of tim e-dependent behavior of concrete. However, most of them are empirical in nature and are limited to the scopes of the experiments. There are great uncertainties in extrapolation to later times and to the c onditions not covered in the laboratory. AASHTO LRFD Specifications state the following: without re sults from tests on the specific concretes or prior experience with the materials, the use of the creep and shrinka ge values referenced in these Specifications can not be expected to yield results with errors less than 50%. The values of the modulus of elasticity, ultimate shrinkage strain and ultimate creep coefficient of concrete, which are used in structural design in Florida, are either based on the arbitrary available literature or based on the lim ited research of the locally available material. Particularly, since very limited creep testing has been performed on Fl orida concretes, the knowledge of creep characteristics of Florida conc rete is still a blind page. More importantly, the susceptibility of th e elastic modulus, shrinkage and creep of concrete to the variation of concrete mix ingredients, such as particular a ggregates in Florida, water content and mineral additives so on, puts more uncerta inties in using these values. There is a great need for a comprehensive testing and evaluation of locally available concrete mixes to determine these mechanical and physical properties of Florida normal-weight as well as lightweight concretes, especially fo r the concretes used in pre-stressed concrete structure, so that correct values for these properties can be used in structural design. In addition,

PAGE 20

21 there is also an immediate need to determine the most effective and practical laboratory test setups and procedures for obtaining the modulus of elasticity, creep and sh rinkage properties of structural concretes used in Flor ida. This research study was carri ed out to meet these needs of the FDOT. 1.2 Hypothesis Creep is related other m echanical properties of concrete, especially strength and elastic modulus. Thus, it is possible to estimate or predict its creep be havior based on the knowledge of its other mechanical properties. Shrinkage of concrete is rela ted to its water content and other mechanical properties, specially strength and elastic modulus. Thus, it is possible to estimate shrinkage behavior from its water content and other mechanical properties. Ultimate creep coefficient of concrete may ex ceed a value of 2.0, which is usually assumed to be the maximum value in structure design. Th us, creep testing on the specific concrete is needed to obtain reliable value of its ultimate creep coefficient. 1.3 Objectives of Study This research has the following m ajor objectives: To design and recommend an effective and relia ble laboratory testi ng set-up and procedure for performing creep tests on concrete. To evaluate the effects of aggregate, minera l additives and water to cementitious materials ratio on strength, elastic modulus, shrinka ge and creep behavior of concrete. To determine the strength, elastic modulus, sh rinkage and creep behavior of the typical concretes used in Florida. To determine the relationship among compressi ve strength, splitting tensile strength and modulus of elasticity of concretes made with ty pical Florida aggregate. To develop prediction equati ons or models for estimation of shrinkage and creep characteristics of typical Florida concretes. 1.4 Scope of Study The scope of this research c overed the following major tasks: To review the literature a bout previous and current study on elastic modulus, shrinkage and creep of concrete.

PAGE 21

22 To design, construct and evaluate the effectiveness of creep test set-up and procedures. To perform a comprehensive laboratory study on the physical and mechanical properties of typical Class II, IV, V and VI concrete mixtures made with normal weight aggregate and lightweight aggregate, in cluding compressive strength, indirect tensile strength, modulus of elasticity, cr eep and shrinkage behavior. A tota l of 14 different concrete mixes was evaluated, and ten of them were replicated. To analyze the experimental data, and to determine the relationships among different properties, and to develop pr ediction equations for estimation of shrinkage and creep behaviors of concrete. 1.5 Research Approach Objectives of this study are realized by the following research approaches: Conduct laboratory testing programs to dete rmine the various properties of concrete. ASTM standard test methods were used for co mpressive strength test, splitting tensile test, elastic modulus test and shrinkage test. A creep test setup was designed, evaluated and refined to be used for this purpose. Perform statistical analysis to determine relationships and trends among the fundamental properties of the concretes evaluated in this study. Evaluate existing prediction models for cree p and shrinkage and develop improved models for estimation of shrinkage and creep behaviors of concrete.

PAGE 22

23 CHAPTER 2 LITERATURE REVIEW 2.1 Introduction The f ollowing content presents a literature review on the susceptibility of strength, elastic modulus, shrinkage and creep prope rties of concrete to variou s factors, and on the existing models for predicting the stre ngth, elastic modulus, and shri nkage and creep properties of concrete. 2.2 Strength of Concrete 2.2.1 Significance of Studying Strength of Concrete Strength is comm only considered as the most valuable property of concrete, and it gives an overall picture of the quality of concrete because of its direct relation to the micro-structure of the hydrated cement paste. Moreover, the strength of concrete is almost invariably a vital element of structural design and is specified for compliance purpose. Also, knowing strength development characteristic of concrete is very critical in decision-making about when to remove formworks, when to continue next construction step, or when to open structure to service. Apparently, the economic analyzer will be very pleased for knowing the aforementioned information to optimize project budget. Over the past decades, with the broad development and application of new concrete technique characterized by high strength concrete and high performance concrete, durable concrete structure and complex structural design become rea lizable. For example, high-rise building enables humankind to make full use of limit living space on this planet plausible; and long-span bridge are more pleasing estheti cally, cost-effective and resource-saving. However, even though a large amount of inform ation has been accumulated about concrete strength design, engineers are still fore from knowi ng well the strength proper ties of concrete. To

PAGE 23

24 design a concrete mixture with preassigned proper ties is still an engineers dream. The causes are attributed to the volatilit y of concrete strength induced by the variation of raw materials and their proportions. Thus, the properties of concre te materials are still worthy of study. 2.2.2 Effect of Coarse Aggregate on Strength of Concrete The investigation on the eff ect of raw m aterials and th eir proportions on strength development has been the focus of many engineers effort. For example, Aitcin and Mehta [Aitcin, P-C a nd Mehta, P. K, 1990] studied the effect of coarse aggregate characteristics on mechanic al properties of high strength concrete. The experiment was carried out using four coarse aggregate types av ailable in Northern California and similar mix proportions. The results showed that using diabase and limestone aggregates produced concretes with signifi cantly higher strength and elastic modulus than those using granite and river gravel. They concluded that the mineralogical differences in the aggregate types were responsible for this behavior. Sarkar and Aitcin [Sarkar, S. L and Aitcin, P-C, 1990] carried out research on the importance of petrological, petrogr aphical and mineralogical charact eristics of aggregate in very high strength concrete. They pointed out that aggregate intrinsic strength, particularly that of coarse aggregates, receives scan t attention from concrete technol ogists and researchers as long as the w/c ratio falls within the 0.50-to-0.70 range, primarily due to the fact that the cementaggregate bond or the hydrated cement paste fails long before aggregates do. This, however, does not hold true for very high-strength concre tes, with very low w/c ratios of 0.20 to 0.30. Compressive strength testing of very high-strength concrete has indicated that aggregates can assume the weaker role, exhibited in the form of transgranular fractures on the surface of failure, as has already been observed in some lightwei ght concretes. The aut hors have carried out detailed petrological, petrogra phical and mineralogical characte rization of twelve different

PAGE 24

25 coarse aggregates that have perf ormed with variable success in very high-strength concrete in Canada and the United States. Suitability for such an application has been linked to a special set of lithological characteristics: th e minerals must be strong, unalte red, and fine grained. Intraand intergranular fissures partially decomposed co arse-grained minerals, and the presence of cleavages and lamination planes tend to weaken the aggregate, and therefore the ultimate strength of the concrete. Ezeldin and Aitcin [Ezeldin, A. S. and Aitcin, P-C, 1991] studied the e ffect of four coarse aggregates with different characteristics on the compressive strength, flexural strength, and flexural strength/compressive st rength ratio of normaland hi gh-strength concretes. The study investigated the possibility of obt aining a relatively high flexural strength/compressive strength ratio at high compressive strength by using different aggregate types. The study by Alexander and Addis [Alexander, M. G. and Addis, B. J., 1992] showed that aggregates play an important role in governing mechanical proper ties of high strength concrete. Generally, andesite and dolomite aggregates give superior resu lts. Tests were also done on "artificial" interfaces between paste and these two rock types in order to characterize the interfacial bond properties. Results show that andesite achieves hi gher interfacial fracture energy values than dolomite, which help s to confirm the macroscopic e ngineering properties measured on concretes. Giaccio, Rocco, Violini, Zappitelli, and Zerbino [Giaccio, G. et al, 1992] pointed out that concrete is a heterogeneous material whose prope rties depend on the properties of its component phases and the interactions between them. They studied the effects of granitic, basaltic, and calcareous aggregates on the mechanical prop erties of high strengt h concrete, including compressive strength, flexural st rength, modulus of elasticity and stress-strain behavior of

PAGE 25

26 concrete. The results indicated that the effect of coarse aggregate characteristics on the mechanical properties of high-stre ngth concretes is substantial. The impact of aggregate strength on concrete compressive strength was evaluated by Lindgard, and Smeplass [Lindgard, J. and Smeplass S, 1993] as well. The significance of the aggregate strength has been compared with the effect of the cement type and the use of silica fume. According to the obtained results, the imp act of the aggregate strength on the strength of high strength concrete is limite d, compared with the impact of the binder type, while the differences in elastic modulus between the differe nt aggregate types is fully reflected in the concrete elastic modulus. This contradicti on is explained by a hypot hesis based on stress concentrations due to the difference in rigi dity between the binder and the aggregates. 2.2.3 Prediction of Strength of Concrete If there is no specific testi ng data available, it is a good a lternative to have an equation reliable to give an effective prediction on the st rength of concrete at desired age. An accurate approximation to the strength of concrete at specific ages is of great impor tance to know in order to decide on when to remove formwork, when to continue next construc tion step, and when to open the structure into service. In analyzing the characteristics of developm ent of compressive strength with time, an empirical equation has been provi ded by ACI 209R Code as follows: 28 )( c f t t t c f (2-1) Where in days and are constants, 28 cf is compressive strength of concrete at 28 days, and t in days is the age of concrete. For the tests using "12"6 cylinder, type I cement and moist curing condition, two constants, and are equal to 4.0 and 0.85 respectively.

PAGE 26

27 Because of substantial effect of coarse aggregate type on th e properties of concrete, and because of no such mineral additives as fly ash and slag involved, which have substantial effects on the development of concrete strength, when the aforementioned formula was developed, caution should be taken when it is used. If possible, further inves tigation should be carried out to calibrate the above equation. 2.3 Elastic Modulus of Concrete 2.3.1 Definition and Determination of Elastic Modulus of Concrete The m odulus of elasticity or Youngs Modulus a very important mechanical property reflecting the capability of concrete to deform elastically, is defi ned as the slope of the stressstrain curve within the proportional limit of a material. Figure 2-1 Representation of the st ress-strain relation for concrete For a concrete material, usually, the most co mmonly used value in structure design is the secant modulus, which is defined as the slope of the straight line drawn from the origin of axes to the stress-strain curve at some percentage of th e ultimate strength. Since no portion of the stressstrain curve is a st raight line, the usual method of determin ing the modulus of elasticity is to measure the tangent modulus, which is defined as the slope of the tangen t to the stress-strain Strain Stress Unloading Loading Initial tangent modulus Tangent modulus Secant modulus

PAGE 27

28 curve at some percentage of the ultimate strength of the concrete as determined by compression tests on "12"6 cylinders. Figure 2-1 illustrate s the stress-strain plot of a concrete as it is loaded and unloaded. From this figure, we can see that the secant modulus is almost identical to the tangent modulus obtained at some lower percentage of the ultimate strength. 2.3.2 Significance of Studying Elastic Modulus of Concrete Concrete, a s a building material, is utilized in the elastic range. Thus, it is very important to know the relationship between st ress and strain for a given concre te before it can be used for buildings, bridges, pavement and so forth. The relationship between stress and strain for a concrete material can be characterized by its el astic modulus, which is th e property of concrete materials. For reinforced concrete structures, the knowledge of the elastic property of a specific concrete will not only make the deformation of the concrete members well-controlled, but also decrease the extra stress transfer to other conc rete elements, which can cause the concrete to crack or fail prematurely. For prestressed concrete struct ures, elastic shortening is blam ed for causing prestress loss. The prestress loss, on one hand, will decrease the cap acity of a concrete stru cture, and even lead to unexpected collapse of the structure; and on th e another hand, it will re sults in the increased volume of tendon for satisfying the design requir ement because of over-estimation on elastic shortening, which can result in possible wa ste of materials and increased cost. In addition, in order to make full use of the compressive strength potential, th e structures using high-strength concrete tend to be slimmer and require a highe r elastic modulus to maintain its stiffness. Therefore, the knowledge of the elastic modulus of high strength concrete is very important in avoiding excessive deformation, pr oviding satisfactory serviceability, and achieving the most cost-effective designs.

PAGE 28

29 At last, for concrete pavement, high elastic modulus concrete is not desirable because it increases the pavement cracking probability. Th us, high strength but low modulus concrete is preferable. As to how to obtain the concrete material with th e properties desired, one way to approach this goal is to change the propertie s of individual concrete components and their proportions. And most importantly, th e significant effects of differe nt types of coarse aggregate on elastic modulus of concrete have to be investigated. 2.3.3 Effect of Coarse Aggregate on Elastic Mo dulus of Concrete Figure 2-2 Stress-strain relations for cement paste, aggregate and concrete Since concrete is a multiphase material, modulus of elasticity is very susceptib le to the variation of coarse aggregate content and coar se aggregate type. In a study by Stock, Hannant and Williams [Stock et al, 1979], it was reported that for concretes with a fixed w/c of 0.5, as the volume of coarse aggregate varied from 20 to 60 %, the compressive strength of concrete remained almost same. This result is very cons istent with the W/C law established by Duff Abrams in 1919. That is to say, for a given mix proportion, the compressive strength of concrete 50 40 30 20 10 0 1000 2000 3000Stress -MPa Strain -10-6 Aggregate Concrete Cement paste

PAGE 29

30 will be determined by its water to cement ratio. Th is is especially true for normal concrete with compressive strength less than 60MPa. Howeve r, the elastic modulus of the concrete was substantially influenced by the changes in its co arse aggregate content. As shown in Figure 2-2 [A.M.Neville, 1996], we can see that the elastic modulus of concre te is remarkably different from that of hardened cement paste. Also, Neville [A.M.Neville, 1996] pointed out that, for a concrete of a given strength, because normal weight aggregate has a higher elastic modulus than hydrated cement paste, a higher aggregate content results in a highe r modulus of elasticity of the concrete. In a study by Persson [Persson, 2001], it was re ported that the elas tic modulus of selfcompacting concrete was the same as that for normal concrete as long as their compressive strengths were the same. However, in the study by Schlumpf [Schlu mpf, 2004], the elastic modulus of self-compacting conc rete was reported to be 20% lower than that of a normal concrete with similar strength. In addition, th e findings from the study by Chi [Chi, 2003] also indicated that the aggregate frac tion in concrete had a considerab le effect on the elastic modulus of concrete. Coarse aggregate type is another very importa nt factor affecting th e elastic modulus of hardened concrete. Different types of aggregate can have quite distinct effects on elastic modulus. Even different coarse aggregates of the same type but from different locations can have substantially different properties. Th e reported findings by Zhou, Lydon and Barr [Zhou et al, 1995] show that the coarse aggregate type ha s a considerable influence on the elastic modulus of concrete. In their study, the effects of expanded clay, sintered fly ash, limestone, gravel, glass and steel aggregate on the elastic modulus of concrete were i nvestigated. In addition, the study

PAGE 30

31 by Shideler [Shideler, 1957] on c oncrete mixtures using gravel and expanded clay as aggregate also indicate the same conclusion as reporte d by Zhou, Lydon and Barr [Zhou et al, 1995]. In 1990, Aitcin and Mehta [P. C. Aitcin and P. K. Mehta, 1990] also investigated the effect of coarse aggregate characteristics on mechanical properties of high strength concrete. In their study, the influence of four coar se-aggregate types available in Northern California on the compressive strength and elastic behavior of a very high strength concre te mixture was studied using identical materials and similar mix proporti ons. The results indicated that the diabase and limestone aggregates were found to produce conc retes with significantly higher strength and elastic modulus than did the granite and river gravel. The mine ralogical differences in the aggregate types are considered to be responsible for this behavior. The study by Alexander [Mark G. Alexander, 1996] on the influence of 23 different aggregate types on the properties of hardened co ncrete showed that a ggregates exert a profound and important influence on the elastic property of concrete. In 1998, Cetin and Carrasquillo [Aykut Cetin and Ramon L. Carrasquillo, 1998] carried out an investigation on the effect s of four coarse aggregate type s locally available in central Texas on the mechanical properties of high-perfor mance concrete. Test results showed that the mineralogical characteristics of coarse aggregate as well as the aggregate shape, surface texture, and hardness appeared to be responsible fo r the differences in the performance of high performance concretes. Also, it was observed th at it appeared that there was no one single equation for high-performance concrete mixtures with different coarse aggregates that coulc estimate the elastic modulus with sufficient accuracy as in the case of nor mal strength concretes. Wu, Chen amd Yao [Wu K.-R, Chen B, Yao W, Zhang D, 2001] carried out a study on the effects of the coarse aggregate type, including crushed quartzite, crushed granite, limestone, and

PAGE 31

32 marble coarse aggregate, on the compressive strength, splitting tensile strength, fracture energy, characteristic length, and elastic modulus of concrete. The results indicated that the stiffness of concrete depends on the type of aggregate, especially for high-strength concrete. Beshr and Maslehuddin [Beshr H et al, 2003] Rashid, Mansur and Paramasivam [M. A. Rashid et al, 2002]; Huo, Al-Omaishi and Tadr os [Xiaoming Sharon Huo et al, 2001] reported that different types of coarse aggregate have pronounced effects on elastic modulus of concrete. 2.3.4 Models for Predicting El astic Modulus of Concrete As m entioned in the literature about the factors affecting elastic modulus of concrete, for a given type of aggregate, although the modulus of elastic ity of concrete will increase with the strength of concrete, the factors that affect the modulus of elasti city of concrete do not always have a corresponding effect on the strength of conc rete. Thus, there is no universal equation that can be possibly applied to relate compressive st rength to elastic modulus of concrete. Thus, the models, both ACI model and CEB-FIP model, may need to be modified in order to be applied to a structure to achieve full func tion and serviceability in its entire life span The above hypothesis can be easily confirmed by an ex tensive testing program to inve stigate the effects of coarse aggregate types on elastic modulus of concrete. The study by Shih, Lee, and Chang [Shih, T. S. et al, 1989] suggested that Young's modulus of high-strength concre te has a somewhat higher value than that of normal-strength concrete. Pauw's equation for modulus of elastici ty of concrete, which is based on experimental normal-strength concrete, needs to be reexamined. Baalbaki, Benmokrane, Chaallal, and Aitcin, [Baalbaki, W., 1991] studied the influence of different types of crushed rocks on elastic pr operties of high performa nce concrete. Testing results pointed to the important role played by co arse aggregates through the elastic properties of

PAGE 32

33 the parent rock. They also recommended that the present formulas relating the prediction of elastic modulus of concrete recommended by some codes should be reviewed. Nilsen and Aitcin [Nilsen, A. U. and Aitcin, P-C., 1992] investigated the properties of high strength concrete containing lightweight, normal weight and heavyweight aggregates. In this study, a comparison of the values of elastic m odulus determined experimentally with those calculated according to the formula recomm ended by the ACI Building Code, the British Standard Code, and the Norwegian Standard Co de, showed that all codes overestimated the elastic modulus of high-streng th heavyweight concrete. In the following section, the formula used to predict the elastic modulus of concrete by Florida LRFD Guidelines, ACI model, and CEB-FIP model are given. Model recommended by Florida LRFD Guidelines [2002] According to this guideline, in the absence of more precise data, the modulus of elasticity for concretes with unit weights between 0.090 and 0.155 kcf, can be estimated from the following formula: c f c w c E (2-2) Where EcElastic modulus in ksi. cw -Unit weight of concrete (kcf). 'cf -Compressive strength of concrete (ksi). -Constant, 33000 is recommended by Florida LRFD Guidelines. -constant, 5.1 is recommended by Florida LRFD Guidelines. Prediction equations recommended by ACI 209

PAGE 33

34 The prediction equations recommended by AC I for estimating the elastic modulus of concrete are given as follows: c fA c E (2-3) Where cE -Elastic modulus (psi) cf-Compressive strength of concrete (psi) A -constant, 57000 Ais recommended by ACI 318. The following equation recommended by ACI 318-89 (revised 1992) for structural calculation is applicable to normal weight concrete: c f c E (2-4) Where cE-Elastic modulus (GPa) cf-Compressive strength of concrete (MPa) -constant, 32.3 is recommended by ACI 318. -constant, 9.6 is recommended by ACI 318. The next equation given by ACI 363R-92 is appl icable for predicting elastic modulus of concretes with compressive strength up to 83 MPa (12000 psi) 65.3 c f c E (2-5) Where cE-Elastic modulus (GPa) cf-Compressive strength of concrete (MPa) CEB-FIP Model (1990)

PAGE 34

35 CEB-FIP Model (COMITE EURO-INTERNATI ONAL DU BETON) Co de (1990) also offers the following model for prediction of timedependent modulus of el asticity. The equation is given as follows: ci E tt st ci E 5.0 5.0 1 / 28 1exp) ( (2-6) Where sA coefficient depending on the type of cement; s = 0.20 for rapid hardening high strength cements, 0.25 for normal and rapid ha rdening cements, and 0.38 for slow hardening cements. t Age of concrete (days). t1-1 day Eci Modulus of elasticity of concrete at age of 28 days. 2.4 Shrinkage Behavior of Concrete 2.4.1 Origin of Shrinkage of Concrete According to the mechanisms of concrete shri nkage, shrinkage of c oncrete consists of plastic shrinkage, autogenous shrinkage (a pro cess known as self-desiccation), drying shrinkage, and carbonation shrinkage. Autogenous shrinkage is the consequence of w ithdrawal of water from the capillary pores by the anhydrous cement particles. Most of the autogenous shrinkage will take place at the early age of hydration of cement. However, for concre te mixtures with a very low W/C ratio, this procedure may last longer if moisture is available from ambient environment. Plastic shrinkage and drying shrinkage are caused by withdrawal of water from concrete under the condition of humidity gr adient between the interior of concrete and air. Plastic

PAGE 35

36 shrinkage may lead to the interc onnection among capillary pores, th e main factor contributing to cracking of concrete at early age as well as increasing permeability of concrete. Carbonation shrinkage is cause d by carbonation of calcium hy droxide in the concrete. Thus, carbonation shrinkage normally takes place on the surface of concrete elements. But, if there are penetrated cracks in concrete, carbonation shrinkage may take place in the interior of concrete. Carbonation of concrete will decreas e the PH-value inside concrete so that reinforcement can be easily corroded. 2.4.2 Significance of Studying Shrinkage of Concrete Shrinkage of concrete, one of the main f actors in determinatio n of the endurance of concrete structure, is a very im portant property of concrete to be evaluated. Excessive shrinkage is blamed for leading concrete to crack, even fail At the early age of conc rete, low early strength can not resist the stresses indu ced by drying shrinkage so that shrinkage-induced cracking can subsequently lead to premature failure of the conc rete structure. Cracks in concrete increase the permeability of concrete and control the corrosion initiation time and corrosion rate of steel reinforcement in the concrete structure. Shri nkage-induced cracks become a severe problem for marine concrete structures or concrete structures close to the coastal re gion. The penetration of aggressive ions through cracks into th e interior of concrete is a very critical factor in causing the corrosion of steel reinforcement. For prestresse d concrete elements, not only does the shrinkageinduced cracking speed up the corrosion of reinforcement, shrinkage deformation, which accounts for up to 15% of total prestress loss, is also one of the main factors contributing to prestress loss. The shrinkage behavior of conc rete is greaty affected by coar se aggregate content, coarse aggregate type, cementitious material content and water content. For instance, an increase in volume of aggregate in concrete will usually lead to a decrease in cement content, which would

PAGE 36

37 lead to reduced shrinkage for the concrete. However, a reduction in cement content does not necessarily cause a reduction in the strength of the concrete. Thus, through optimizing mix proportion of concrete mixture, it is possible to design a concrete with low cement content and low shrinkage without s acrifice of strength. 2.4.3 Effect of Raw Materials on Shrinkage of Concrete 2.4.3.1 Effect of aggregate co ntent on shrinkage behavior of concrete The contribution of coarse aggregate to decreased shrinkage of concrete is attributed to the decrease of cement paste volume in the concre te mix. In 1956, Pichett [G.Pichett, 1956] reported that the shrinkage ratio increases signifi cantly as the aggregate content decreases. The possible reason to explain the effects of coarse ag gregate content on shrinkage strain of concrete is shown in Figure 2-3. For the l ean concrete mixture with a high coarse aggregate content, the coarse aggregate particles will have point-to-poi nt contacts or even face-to-face contacts with each other. So a concrete with such a stiff aggreg ate skeleton will be very effective in resisting stresses caused by cement paste shrinkage because aggregate particles cannot be pushed more closely under the action of inte rior stress cause by shrinkage Thus, shrinkage strain is dramatically reduced. But, for rich co ncrete, the situation is otherwise. Figure 2-3 Effect of coarse aggregate content on the shrinkage of concrete a. Lean concrete b. Rich concrete CA Mortar

PAGE 37

38 Similarly, in 1960, Hermite [R.LHermite, 1960] carried out a study of the effects of cement content on shrinkage behavior of conc rete. The tests were performed at a curing temperature of 68oF, 50% relative humidity and wind velo city of 2.25 mph. The results indicated that, at the early age of concrete the shrinkage strain of the c oncrete with a cement content of 850 lb/yd3 (typical cement content for fl owable concrete) is almost three times higher than that of concrete mixtures with a cement content of 340 lb/yd3. Leming [Leming, M. L, 1990] investigated th e mechanical properties of high strength concrete with different raw mate rials. These materials represent those used in structures built under North Carolina Department of Transportatio n control. The data from shrinkage tests showed that shrinkage strain of concrete va ries significantly dependi ng on the specific raw materials used and the strength levels attained. Research was carried out by Alfes [Alfes, 1992] on how shrinkage was affected by the aggregate content, the aggregate modulus of elasticity, and the silica fume content. The experiment was conducted using W/C ratio in the range of 0.25 to 0.3 with 20% silica fume by weight of cement and varying amount and type of aggregates (basalt, LD-slag, and iron granulate), and compressive strengt h of concretes at 28-day age we re in the range of 102 to 182 MPa (14,600 to 26,000 psi). The test results showed that there is a direct and linear relationship between the shrinkage value and the modu lus of elasticity of the concrete. In 1993, Zia et al. [Zia et al, 1993c, 1993d, 1993e] evaluated the shrinkage behavior of VES, HES, VHS concretes with different aggregates (crushed granite, marine marl, rounded gravel, and dense limestone). Shrinkage measuremen ts were made for three to nine months in different cases. The observed behavior followed the general trend of conventional concrete except for the two cases of VES concrete using special blended cement (Pyrament) with marine

PAGE 38

39 marl and rounded gravel as aggregates. In these two cases, the specimens exhibited an expansion of approximately 140 microstrains, rather than shrinkage for th e entire period of 90 days. The expansion was attributed to the lack of evaporable water in the concrete because of its very low W/C (0.17 for marine marl, and 0.22 for rounded gravel). 2.4.3.2 Effects of coarse aggregate type on concrete shrinkage The skeleton of coarse aggregate in a concre te can restrain the shrinkage of the cement matrix. The extend that the coarse aggregate sk eleton can resist the stress caused by shrinkageinduced stress from cement matrix depends on how stiff the coarse aggregate is. That is to say, the elastic modulus of the aggregate determines th e extent of restraining action to the shrinkage of concrete. For example, the shrinkage of a c oncrete made with a steel aggregate will be lower than the one made with a normal aggregate. Sim ilarly, the shrinkage of a concrete made with expanded shale aggregate will be higher than the one made with a normal aggregate. The above hypothesis was verified by the many studies performed in the past decades. In 1958, Troxell, Raphael and Davis [Troxell et al, 1 958] performed tests to study the effects of coarse aggregate of differe nt types on shrinkage be havior of concrete. Th e tests were carried out on the concrete mixtures with a fixed mix pr oportion. The results showed that there is a considerable variation in the sh rinkage strain of the resulting concrete batched with coarse aggregate of different types. They made a conclu sion that this phenomenon is due very likely to the difference in modulus of elasticity among aggr egates of different types. Generally speaking, the elastic property of aggregate determines the degree of restraint to the cement matrix. Reichard [Reichard, 1964] agreed that the coarse aggregate has significant effect on shrinkage behavior of concrete. A normal natural aggregate is usually not subject to shrinkage. However, there exist rocks that can shrink up to the same magnitude as the shrinkage of concrete made with non-shrinking aggregate.

PAGE 39

40 2.4.3.3 Effects of size and shape of coarse aggregate on concrete shrinkage Aggregate size and shape also affect the shrinkage of hardened concrete. The experimental study conducted by Collins [Collins, 1989] on shrinka ge of five high-strength concrete mixtures with varied paste content, aggregate size showed that shrinkage deformations were somewhat less for concrete mixtures with lower past e contents and larger aggregate size. A study by Bisschop, Pel, and Van Mier [Bisschop et al, 2000] indicated that the total length and the depth of micro-cracking caused by sh rinkage of concrete will increase with larger aggregate size. McQueen, Rapol, Flynn [Roy D. McQueen et al, 2002] performed laboratory shrinkage tests in accord ance with ASTM C 157 on a matrix of 16 concrete mixes to evaluate the effects coarse aggregate size on shrinkage of c oncrete. The tests were conducted on mixes with ASTM C 33, No.57 (38-mm maximum aggreg ate size) and No. 467 (64-mm maximum aggregate size) coarse aggregates. The results of the laboratory shrinkage tests revealed that the maximum size of the coarse aggregate (No.57 or 467) did not influence the shrinkage. A study on evaluation of high performance concrete pavement carried out by Ozyildirim [Ozyildirim, C, 2000] showed that concrete usi ng smaller coarse aggregate commonly exhibits greater shrinkage and increases potential fo r slab cracking because of increased paste requirements. Larger maximum coarse aggregate si zes, on the other hand, re quire less paste, less cementitious material, and less water, thereby resu lting in reduced shrinkage; they also provide increased mechanical interl ock at joints and cracks. Thus, there is still some controversy about how coarse aggregate size will affect the shrinkage behavior of concrete. Test data from the specific concrete are necessary to control concrete quality.

PAGE 40

41 2.4.3.4 Effect of other factors on shrinkage behaviors of concrete Shrinkage behavior of concrete is affected not only by coarse aggreg ate, but also by other factors, such as water content, specimen size, ambient conditions, admixtures as well as mineral additives. Water content is the most important factor influencing shrinkage behavior of concrete. Normally, the higher the W/C ratio is, the hi gher the shrinkage. This occurs due to two interrelated effects. As W/C increases, paste strength and stiffness decrease; and as water content increases, shrinkage potential increases. The specimen size affects the diffusion rate of fr ee water from the interior to exterior of concrete. Thus, both the rate and the total magnitude of shrinkage decrease with an increase in the volume of the concrete member because, for larger members, more time is needed for shrinkage effects to reach the in terior regions. For instance, the study by Hindy et al. [Hindy et al, 1994] showed that dry shrinkage of small sp ecimens measured by the conventional laboratory test was found to over-estimate shrinkage of the concrete in the real structure. Ambient conditions, such as relative humid ity and temperature, greatly affect the magnitude of shrinkage. They are blamed for affe cting shrinkage behavior because they create the relative humidity gradient a nd relative temperature gradient be tween the interior and exterior of concrete, which is driving fo rce to concrete shrinkage. The higher the relative humidity, the lower the rate of shrinkage is. The lower the te mperature gradient, the lo wer the shrinkage rate is. Thus, the investigation conducted on shrinkage be havior of concrete has to simulate the real environmental conditions in order not to overestimat e shrinkage strain. For example, Aitcin et al. [Aitcin et al, 1990] reported that the surface sh rinkage strains under the field condition were considerably lower than those measured under the laboratory conditions.

PAGE 41

42 Mineral additive effect on shrinkage behavior varies according to the type of mineral additive. Any material which substantially changes the pore structure of the paste will affect the shrinkage characteristics of the c oncrete. In general, as pore refine ment is enhanced, shrinkage is increased. Pozzolans typically increase the drying shrinkage, due to several factors. With adequate curing, pozzolans generally increase por e refinement. Use of a pozzolan results in an increase in the relative paste volume due to the following two mechanisms: 1) In practice, slowly reacting pozzolans (such as Class F fly ash) ar e frequently added to replace cement by weight rather than by volume according to conventional concrete mix design method. This will increase paste volume since pozzolans have a lower sp ecific gravity than Portland cement. 2) Additionally, since pozzolans such as fly ash an d slag do not contribute significantly to early strength, concrete containing pozzo lans generally has a lower stiffn ess at earlier ages as well, making them more susceptible to increased shrinkage under standard testing conditions. 2.4.4 Models to Predict Concrete Shrinkage Misprediction of shrinkage usually does not cau se structural collapse, but puts the structure out of service, i.e. the structure does not live as long as the proj ected life span. The widespread occurrence of such lack of l ong-term serviceability inflicts a tremendous economic damage on many nations. The direct signs of damage that put a structure out of service are typically cracks, which may cause major fractures. Even though the mechanisms of shrinkage, such as micromechanics mechanism and diffusion mechanism, have been studied extens ively, their correlations with macroscopic behaviors have been intuitive and non-quantitative. As pointed out by Bazant and Carol [Bazant et al, 1993], such studies genera lly have not borne much fruit. Since the uncertainty in the prediction of shrinkage behavior with the variations of concrete compositions and random environmental conditions is enormous, the m odels established at present relies on purely

PAGE 42

43 empirical relations without micromechanics models involved. In addition, substantial effort has been paid in stochastic phenomena and probabilis tic models, but similar to the preceding topic, nothing is being introduced into practice. At present, the empirical formula given by the ACI Committee 209 [1993] is widely used to predict shrinkage strain. But, it should be not ed that ACI 209 equation could well be in error unless broad corrections are applied, for instance to correct for curing and size effect, and to account for humidity and composition effects. As pointed out by Hindy et al. [Hindy et al, 1994], the ACI 209 predictive equation was found to be valid for the high performance concretes only if new values for the parameters were introduced. Thus, owing to many uncertainties in current models, it is very necessary to perform tests on the specific concrete mixtures designed using lo cal available materials to guarantee the safety of structures. Then, based on the accumulated data, constitutive parameters characterizing the shrinkage behaviors of concretes designed based on local available materials can be obtained. In the following sections, the shrinkage pred iction models offered by CEB-FIP model code (1990) and ACI-209 (1992) ar e reviewed briefly. 2.4.4.1 CEB-FIP Model for shrinkage strain prediction In this model, the effects of cement type, ambient relative humidity, compressive strength of concrete, and size effect of specimen on sh rinkage strain of concrete are taken into consideration. The total shrinkage strain ma y be estimated by the following equation: s tt scss tt cs 0 (2-7) Where scstt -Time dependent total shrinkage strain 0 cs -Notational shrinkage coefficient

PAGE 43

44 s (t ts)-Coefficient to describe the deve lopment of shrinkage with time 0 cs can be estimated by the following equation: RH cmo f cm f sc cs 6 10 910160 0 (2-8) Where sc -A coefficient which depends on the type of cement: 4 sc for slowly hardening cements; 5 for normal or rapid ha rdening cements; 8 for rapid hardening high strength cements. cmf -The mean compressive strength of concrete at the age of 28 days. cmof =1 MPa sRH RH 55.1 for %99 %40 RH; 25.0 RH for %99 RH Where 3 0 1 RH RH sRH (2-9) RH The relative humidity of the ambient environment (%). 0RH -100% sstt can be estimated by the following equation: 5.0 1 2 0 350 1 t s tt h h t s tt s tt s (2-10) Where

PAGE 44

45 u A hc2 The notational size of member (in mm), where Ac is the cross-sectional area (mm2) and u is the perimeter (mm) of the me mber in contact with the atmosphere. 0h -100 mm 1t-1 day 2.4.4.2 Prediction model recommended by ACI-209 Report [1992] The concrete shrinkage prediction model recommended by ACI-209 (1992) is shown by the following equation: u sh t t t sh 35 (2-11) Where t sh Time dependent shrinkage strain u sh Ultimate shrinkage strain t Time in days If there is no available shrinkage data from the concrete to be evaluated, the ultimate shrinkage strain,u sh can be assumed to be the following: shu sh 610780 (2-12) where sh a product of all the applicable correction factors for the testing conditions other than the standard condition; sh = 1 under standard testing condition. sh is obtained by multiplying the ultimate shrinkage strain under the standard condition by the appropriate correction factors as described in the following: Correction factors for the effect of initial moist curing. The corre ction factor is equal to 1.0 for concrete cylinders moist-cured for 7 days, and 0.93 for that moist-cured for 14 days.

PAGE 45

46 Correction factor for the effect of ambient relative humid ity. The following formulas are given for use in obtaining the correction f actor for shrinkage test performed under the condition of ambient relative humidity greater than 40%. 0102.040.1 for 8040 (2-13) 030.000.3 for 100 80 (2-14) where Correction factor for the e ffect of relative humidity Relative humidity Correction factor for the effects of specimen si ze. The correction factor in consideration of the specimen size effect (vs ) is given by the following equation: )12.0exp(2.1 s vvs (2-15) where vs Correction factor for the effects of specimen size s v Volume-surface area ratio of the specimen in inches Correction factor for concrete compositi on. Various equations for calculating the correction factors for the effect s of the slump of the fresh concrete, aggregate content, cement content and air content of the concrete have also been given in this model. 2.5 Creep of Concrete 2.5.1 Rheology of Materials and Defi nition of Creep of Concrete The philosophical origin of rheo logy is owed to Heraclitus. As exemplified in his famous aphorism "Panta Rhei" ("Panta Rei"): Ever ything flows and nothing stands still. Inspired by this expression, rheology, the term was coined by Eugene Bingham, a professor at Lehigh University, in 1920, and wa s defined as the study of the deformation and flow of matter under the influen ce of an applied stress. One of the tasks of rheology is to empirically establish the relationships betw een deformations and stresses by adequate measurements. Such relationships are then amenable to mathematical treatment by the established methods of continuum mechanics.

PAGE 46

47 The rheological phenomenon of concrete materials, also termed as creep, is one of very important rheological properties of concrete. Since creep behavior of concrete is characterized by time-dependence, it generates subs tantial effects on the st ructural stability dur ing its service life. Thus, it is of great importance to know the creep behavior of speci fic concrete before it can be used for structure design. Figure 2-4 Creep diagram of concrete material Creep of concrete can be defined as the time -dependent deformation of concrete materials under a sustained stress. As shown in Figure 2-4, load-induced creep consists of three stages, namely primary or transient creep stage, steady-st ate creep or secondary cr eep stage and tertiary creep stage. The primary or transient creep is characterized by a monotonic decrease in the rate of creep. The feature of secondary or steady-state creep is that mate rial will show constant creep rate. At last, in tertiary creep stage, creep rate will increase t ill material fails. Figure 2-5 shows a plot of strain versus time for a concrete that was loaded for some time and then unloaded. The permanent strain that rema ins after the load has b een released is called the creep strain. For concrete materials, creep stra in consists of two main components. The first component is the true or basic creep, whic h occurs under the conditions of no moisture movement to or from the ambient medium. This is the case for concrete element functioning as Time Cree p strain Transient creep Stead y -state cree p Tertiary creep

PAGE 47

48 underground foundation, or inside water. The second component is the drying creep, which takes place while concrete is subjected in ambient conditions. Normally, the creep strain that is considered in structural design is the sum of basic creep strain and drying creep strain. Due to the difficulty to differentiate delaye d elastic strain from creep strain and the convenience to build a numerical model to simula te time-creep strain curve with the delayed elastic deformation included, the total creep stra in would usually include both the delayed elastic deformation and permanent creep deformation. Also, the above mentioned approach is usually taken since the delayed elastic stra in is usually very small compared with the total creep strain. The creep behavior of concrete materials play s a great role in the stability of concrete structures. Also, the creep behavior of concrete is subj ected to the severe volatility caused by the variation of raw materials for c oncrete mixtures and their propor tions. Therefore, over the past decades, the study on creep of concrete has been one of engineers focuses. Figure 2-5 Strain-time plot of concrete under a sustained load and af ter release of load 2.5.2 Significance of Studying Creep Behavior of Concrete Creep in concrete can have both positive as we ll as negative effect s on the performance of concrete structures. On the positive side, cr eep can relieve stress concentrations induced by Time since application of load Strain Instantaneous recovery Delayed elastic recovery Permanent creep Elastic strain

PAGE 48

49 shrinkage, temperature changes, or the movement of supports. For example, in indeterminate beam with two fixed ends, creep deformation will be very helpful in reducing tensile stress caused by shrinkage and temp erature variation. On the other hand, in some concrete structur es, creep can do harm to the safety of the structures. For instance, creep deformation can lead to an excessive deflection of structural members, creep buckling or other serviceability problems especi ally in high-rise building, eccentrically loaded columns and long bridges. In mass concrete, creep may be a cause of cracking when a restrained concrete mass undergoes a cycle of temperature change due to the development of heat of hydration and subsequent cooling. For prestresse d concrete structures, such as composite bridges, pre-stressed shells or continuous girders, the desirable creep of concrete would be as low as possible. Heavily pre-stressed members and long members are particularly susceptible to larg e volume changes. If a pre-stressed member is restrained in position prior to the majority of the volume ch ange has taken place, the pre-stressed members will exert excessive forces on its connections and supporting structures that could cause a structural failure. Also, another very important issue caused by creep deformation is prestress loss, accounting for more than 25% of total prestress loss. 2.5.3 Effect of Aggregate on Creep of Hardened Concrete Aggregates play an important role in creep of concrete. Coarse aggregate reduces creep deformation by reducing the cement paste content and restraining the cement paste against contraction. Generally, concrete s made with an aggregate that is hard and dense and have low absorption and high modulus of elasticity are de sirable when low creep strain is needed. The study by Troxell, Raphael, and Davis [Troxe ll et al, 1958] indicat ed that the creep strains of the concrete mixtures with different types of aggregate will behave differently. The

PAGE 49

50 highest creep value is obtained from the concrete made with sandstone aggregate, and the lowest creep value is obtained from the concrete made with limestone. Rsch et al [Rsch, 1963] found an even grea ter difference between the creep strains of concretes made with different a ggregates. After 18 months under th e load at a relative humidity of 65%, the maximum creep strain of the concre te made with sandstone was five times higher than the minimum creep strain of the concrete made with basalt. Alexander, Bruere and Ivanusec studied th e influence of 23 aggregate types on creep deformation of concrete [Alexa nder et al, 1980]. Creep tests were conducted in a controlled environment at 23 C and 60 % relative humidity. Creep tests were conducted for six months after a 28-day water cured period in lime-saturated water to allow for minimal effects of hydration. Strains were measured using longitu dinal gages on two opposite faces of the prism with a gage length of 100 mm (4 in). The c onclusion shows that aggregates with a lower absorption will produce concrete wi th a lower creep deformation. It was further determined that the aggregate with a high elastic m odulus will produce low creep values. Collins [Collins, 1989] examined the creep prope rty of high strength concrete. Creep tests were conducted according to ASTM C 512. The results demonstrated that a concrete with a larger aggregate size and lower paste cont ent would provide a lower creep strain. Creep tests done by Hua [Hua, 1995] on pure hardened cement pastes and on a reference concrete (made with the same paste) also s how that creep is reduced by the presence of aggregate. In addition, the conclusion on the effect of coarse aggregate content on creep of concrete is also confirmed by the tests on lightweight aggregate concrete. The study by Geso lu, zturan

PAGE 50

51 and Gneyisi [Geso lu et al, 2004] showed that concrete s containing higher lightweight coarse aggregate content had a lower creep strain at all W/C. 2.5.4 Prediction Models and Their Limita tions of Concrete Creep With the exception of creep buckling, overest imation or underestimation of creep usually does not lead to structural collapse, but merely shortens the structur al service life. But, misprediction of creep could put tremendous economic loss. Thus, accurate prediction of the ultimate creep st rain of concrete is of great importance. In order to obtain an accurate prediction, the foll owing mechanisms possibly resulting in creep of concrete have been studied, including micromechanics m echanism, diffusion phenomenon, thermodynamics mechanism, and other mechanism coupled with damage and fracture. Micromechanics mechanism in creep behavior has been studied extensively through the study of the microstructure of cement and conc rete for decades. However, the macroscopic constitutive relations based on the intuitively and non-quantitatively observed phenomenon or postulated on the microstructure or even molecu lar level generally are not promising. The uncertainty in the prediction of long-term creep associated with the variations of concrete composition is enormous, actually much larger than any uncertainty except that due to the randomness of environment. Thus, even though the attempts at the mathematical micromechanical modeling of some phenomena have already begun, there is sill quite a distance to make them practical. Diffusion phenomenon can be considered anot her very important mechanism for creep behavior of concrete because creep of concrete is always associated with the moisture and heat transport between the interior concrete and out side environment. Therefore, in concrete structures exposed to the envir onment or subjected to variable temperatures, there is no hope of obtaining realistic stresses without actually solving the associated problems of moisture and heat

PAGE 51

52 transport, at least in an approximate manner. It has been shown that creep and shrinkage analysis based on diffusion analysis of a box girder bridge segment yields enormous stresses which are routinely neglected in practice. The models based on statistics have been studied extensively. Although the statistical variability of concrete creep under controlled la boratory conditions is qui te small, very large statistical fluctuations are caused by the environmen t as well as the uncerta inties in the effect of concrete composition. In most practical situations, sophisticated deterministic mathematical analysis makes in fact little sense, because the un certainties of stochastic origin are much larger than the errors of simple effective modulus solutions compared with sophisticated deterministic analytical solutions of differe ntial or integral equations. Due to complex influences coming from raw materials and ambient environment, the common problem with the current models is that th ey are only feasible to be used for the creep prediction of similar concretes, which means c oncretes from the same geographical region. The concretes used in the Florida region are genera lly quite similar and, instead of repeating measurements for each new major structure, one can greatly improve predictions on the basis of previously obtained data for a similar concrete from the same region. Equally important will be application of the existing fundament al research results in practice. Since each of these models is applicable under specific conditions for a certain class of material s, the proper utilization of these models depends essentially on the practical e xperience of the researcher. The accumulation of this experience is the purpose of most experimental works on creep. This is due mainly to the fact that 1) more than one microscope mech anism are involved in induc ing creep of concrete, and 2) some empirical models only can be used for certain types of concretes without the variation of concrete compone nts, proportions and applied e nvironmental conditions. If the

PAGE 52

53 empirical model obtained from the concretes used in a given region is ap plied to predict creep strain of the concretes in another region, the result s could be very scary. Over the years, many equations have been deve loped for the description of steady-state and transient creep. But, most of them are either too complicated theoretically to bring them into practical use, or have an empirical character a nd were determined on the basis of a fit to the experiments, which cause great uncertainties in the extrapolation to long time intervals and to conditions not covered in the laboratory. In the following sections, two creep predic tion models, namely CEB-FIP model and ACI 209 model will be reviewed. 2.5.4.1 C.E.B-F.I.P Model Code In this model, the creep strain can be predicted by the following equation: ) 0 ,( 28 ) 0 ( ) 0 ,( tt ci E t c tt cr (2-16) Where ),(0ttcr Creep strain at time t )(0tc -Applied stress ),(028tt Creep coefficient ciE Modulus of elasticity at the age of 28 days The modulus of elasticity can be estimated by the following equation: 3 1 )( 4 10 cmo f f ck f Eci E (2-17) Where

PAGE 53

54 ckf Characteristic strength of concrete (in MPa);MPaf8 ;MPa fcmo10 ; MPaE41015.2 The creep coefficient ) ,(028tt can be calculated as follows: ) 0 ( 0 ) 0 ,( 28 tt c tt (2-18) Where 0 Notational creep coefficient. c Coefficient to describe the developm ent of creep with time after loading t Age of concrete in days 0t Age of concrete when loaded in days The notational creep coefficient can be estimated as follows: 2.0 ) 1 / 0 (1.0 1 ) 0 ( / 3.5 )( 3/1 ) 0 /(46.0 0 /1 1 ) 0 ()( 0 tt t cmo f cm f cm f hh RHRH RH t cm f RH (2-19) Where fffck cm h Notational size of the member (in mm) uAc/2 cA Cross-sectional area (in mm2) u Perimeter of the member in contact with the atmosphere (in mm) 0h 100 mm. RH Relative humidity of the ambient environment (in %).

PAGE 54

55 0RH 100% 1t 1 day. 1500250 0 18 0 2.11150 3.0 1 /) 0 ( 1 /) 0 ( ) 0 ( h h RH RH H ttt H ttt tt (2-20) 2.5.4.2 Model of ACI 209 In the ACI 209 (1992) model, the creep coefficient is estimated as follows: 6.0 ) 0 (10 6.0 ) 0 ( ) 0 () 0 ,( 28 tt tt ttt (2-21) Where ),(028tt Creep coefficient at time t )(0t Ultimate creep coefficient to Time of loading The ultimate creep coefficient can be expressed as: c t ) 0 ( (2-22) The constant 35.2 is recommended. The correction factors c consist of the following terms: asatRHlac (2-23) Where

PAGE 55

56 la Correction factor for loading age. For lo ading ages later than 7 days and moist cured concrete, 118.0 0)(25.1tla. For loading ages later th an 1-3 days and steam cured concrete, 094.0 0)(13.1tla RH Correction factor ambient relative humidity. For ambient relative humidity greater than 40%, RHRH 0067.027.1 (RH is the ambient relative humidity in %) s Correction factor for slump of fresh concrete. l sS 00264.082.0 (lS in mm) Correction factor for fine to total aggregate ratio. a 0024.088. 0 (a is fine to total aggregate ratio) a Correction factor for air content. a aa 09.046.0 (aais air content) at Correction factor for thickness of member. When the average thickness or volume to surface ratio of a structural member differs from 150 mm or 38 mm, respectively, two methods are offered for estimating the factor of member sizeat : Average-thickness method For an average thickness of a member sma ller than 150 mm, the factors are given by ACI209 Report. For an average thickness of a me mber larger than 150 mm and up to about 300 to 380 mm, the correction factor for thickness is given as: a ath 00092.014.1 During the first year after loading a ath 00067.010.1 For ultimate values Where ah= Average thickness of a member in mm. Volume-surface ratio method s v ate0213.013.11 3 2 (2-24)

PAGE 56

57 Where s v = Volume to surface ratio in mm.

PAGE 57

58 CHAPTER 3 MATERIALS AND EXPERIMENTAL PROGRAMS 3.1 Introduction This chapter describes the mix proportions and ingredients of typical concrete mixtures used in this research, the met hod of preparation of the concrete mixtures, fabrication procedure of the test specimens and routin e ASTM testing methods and proce dures used in this study. 3.2 Concrete Mixtures Evaluated 3.2.1 Mix Proportion of Concrete The concrete mixtures were randomly select ed from typical Class II, IV, V and VI concretes made with normal-weight and lightweight aggregates. They are re presentative concrete mixes broadly used in Florida. The range of de signed compressive strength of concretes varied from 4,000 to 11,000 psi at the age of 28 days. Class F fly ash and gr ound blast-furnace slag were used as additives in these mixes. Water reducing and air entraining admixtures were used throughout all the mixtures. Water to cementitious materials ratio for all the mixtures was determined according to the design strength of specified concre te. Workability of fresh concrete in terms of slump value, was controlled by the dosage of water reducer, supe r plasticizer and air en training agents. Since strength of concrete is very se nsitive to the variation of air co ntent and water content, to meet target slump value, the dosage of water reducer a nd superplasticizer were adjusted rather than the dosage of air entraining agent and water. In addition, another r eason to add air entraining agent to concrete is to improve durability of concrete. A total of 14 different concrete mixtures were evaluated. The deta iled mix proportions for the fourteen mixtures are presente d in Table 3-1. Miami Oolite limestone was used as a coarse aggregate for Mix-1F, 2F, 3F, 4F, 5S, 6S, 7S, and 8S. Stalite lightweight aggregate was used for

PAGE 58

59 Mix-9LF and Mix-10LS. Mix-2G F, Mix-3GF, Mix-5GS and Mix-7GS had identical mix proportion to the Mix-2F, Mix-3F Mix-5S and Mix-7S with th e exception that the coarse aggregate was replaced by a granite aggregate by volume. Fly ash was used in Mixes 1F, 2F, 3F, 4F, 9LF, 2GF and 3GF, and slag was used in Mixes 5S, 6S, 7S, 8S, 10LS, 5GS and 7GS. Mixes 1F, 2F, 3F, 4F, 5S, 6S, 7S, 8S, 9LF and 10LS were replicated. 3.2.2 Mix Ingredients The mix ingredients used in producing the c oncrete mixtures are described as follows: Water Potable water was used as mixing water for pr oduction of the concrete mixtures. The water temperature was around 64oF. Cement Type-I Portland cement from CEMEX Company was used. The physical and chemical properties of the cement as provided by Florid a State Materials Office are shown in Table 3-2 and Table 3-3. Fly ash The fly ash used in this study was provided by Boral Company. Its physical and chemical properties as provided by Flor ida State Materials Office ar e presented in Table 3-4. Slag The slag used in this study was provided by Lafarge Company. Its physical and chemical properties as provided by Florida State Ma terials Office are s hown in Table 3-5. Fine aggregate The fine aggregate used was silica sand from Go ldhead of Florida. The physical properties of the fine aggregate as determined by Florid a State Materials Office are shown in Table 36. The gradation of the fine aggregate is shown in Figure 3-1. The fine aggregate was oven-dried before it was mixed with the othe r mix ingredients in the production of the concrete mixtures. Air-entraining admixture The air-entraining admixture used was Darex AEA from W.R. Grace & Co. Darex AEA is a liquid admixture for use as an air-entraini ng agent, providing freeze thaw durability. It contains a catalyst for more rapid and comple te hydration of Portland cement. As it imparts

PAGE 59

60 workability into the mix, Darex AEA is partic ularly effective with slag, lightweight, or manufactured aggregates which te nd to produce harsh concrete. Coarse aggregates Three different types of coarse aggregates were used in this study. The first one is a normal weight Miami Oolite limestone. The second on e is Georgia granite aggregate. The third one is called Stalite, a lightweight aggr egate from South Carolina. The physical properties of these three coarse aggregates are displayed in Table 3-7. The gradation of the Miami Oolite is shown in Figure 3-2; the grad ation of the Georgia granite aggregate is plotted in Figure 3-3; and the gr adation of Stalite aggregate is presented in Figure 3-4. In order to have a good control on the moisture content of coarse a ggregates, the coarse aggregates were soaked in water for at leas t 48 hours and then drained off the free water on the surface of aggregate before they were mi xed with the other mix ingredients in the production of the concrete mixtures. Water-reducing admixture The water-reducing admixture used incl uded WRDA60, WRDA64, and ADVA120 from W.R.Grace & Co. WRDA 60 is a polymer base d aqueous solution of complex organic compounds producing a concrete with lower water content (typically 8-10% reduction), improved workability and higher strengths. It can be used in ready mix, job site and concrete paver plants for normal and lightweight concrete. It also can be used in block, precast and prestress work. In addition, it o ffers significant advantages over single component water reducers and performs especia lly well in warm and hot weather climates to maintain slump and workability in high ambient temperatures. WRDA 64 is a polymer based aqueous solution of complex organic compounds producing a concrete with lower water content (typically 8-10% reduction), gr eater plasticity and hi gher strength. Except significant advantages like WR DA 60, WRDA 64 performs especially well in concrete containing fly ash and other pozzolans. ADVA 1 20, a superplasticizer, is a polymer based liquid organic compounds increasing plasticity of concrete. 3.3 Fabrication of Concrete Specimens 3.3.1 The Procedure to Mix Concrete The concrete mixtures investigated in this study were produced in the laboratory using a compulsive pan mixer with capacity of 17 cubic f eet, as shown in Figure 3-5. For each mixture, thirteen (13) cubic feet of fresh concre te was produced to fabricate sixty (60) "12"6 cylindrical specimens.

PAGE 60

61Table 3-1 Mix proportions of the 14 conc rete mixtures used in this study Admixture Coarse Agg. No. of Mix W/C Cement (lbs/yd3) Fly ash (lbs/yd3) Slag (lbs/yd3) Water (lbs/yd3) FA (lbs/yd3) CA (lbs/yd3) AE WRDA/ADVA Mix-1F* 0.24 800 200 --236.0 931 1679 7.5 OZ (WRDA60)-30OZ (ADVA120)-60OZ Mix-2F* 0.33 656 144 --265.6 905 1740 12.0 OZ (WRDA60) -30OZ Mix-3F* 0.41 494 123 --254.0 1175 1747 0.5 OZ (WRDA60)-33.4OZ Mix-4F* 0.37 600 152 --278.0 1000 1774 2.0 OZ (WRDA60) -56OZ Mix-5S* 0.33 400 --400 262.0 1062 1750 6.0 OZ (WRDA60)-24OZ (ADVA120)-48OZ Mix-6S* 0.36 380 --380 270.0 1049 1736 1.9 OZ (ADVA120) -38OZ Mix-7S* 0.41 197 --461 267.0 1121 1750 4.6 OZ (WRDA60)-32.9OZ Miami Oolite Mix-8S* 0.44 306 --306 269.0 1206 1710 3.1 OZ (WRDA60)-30.6OZ Mix-9LF* 0.31 602 150 --235.3 952 1239 9.6 OZ (WRDA64) -30OZ Stalite lightweight Mix-10LS* 0.39 282 --423 275.0 853 1300 8.8 OZ (WRDA64)-31.7OZ Mix-2GF 0.33 656 144 --265.6 909 1981 12.0 OZ (WRDA60) -30OZ Mix-3GF 0.41 494 123 --254.0 1176 2027 0.5 OZ (WRDA60)-33.4OZ Mix-5GS 0.33 400 --400 262.0 1066 2045 6.0 OZ (WRDA60)-24OZ (ADVA120)-48OZ Georgia Granite Mix-7GS 0.41 197 --461 267.0 1125 2045 4.6 OZ (WRDA60)-32.9OZ Note: AE-air entraining admixture; Mixtures were replicated.

PAGE 61

62Table 3-2 Physical properties of Type I cement Loss on Ignition (%) Insoluble Residue (%) Setting Time (min) Fineness (m2/kg) Compressive Strength at 3 days (psi) Compressive Strength at 7days (psi) 1.5% 0.48% 125/205 402.00 2400 psi 2930 psi Table 3-3 Chemical ingredients of Type I cement Ingredients SiO2 Al2O3 CaO SO3 Na2O-K2OMgO Fe2O3 C3A C3S C2S C4AF+C2F (%) 20.3% 4.8% 63.9% 3.1% 0.51% 2.0% 3.3% 7% 59% 13.8% 15.8% Table 3-4 Physical and chem ical properties of fly ash SO3 (%) Oxide of Si, Fe, Al (%) Fineness (%) (ASTM C430) Strength(7d) (ASTM C109) Strength (28d) (ASTM C109) (%) Loss on Ignition (%) (ASTM C311) % of Water (ASTM C-618) 0.3 84 32 N/A 78 4.3 102 Table 3-5 Physical and chemical properties of slag SO3 (%) Oxide of Si, Fe, Al Fineness (%) (ASTM C430) Strength (7d) (%) (ASTM C109) Strength (28d) (ASTM C109) (%) Loss on Ignition (%) (ASTM C311) % of water (ASTM C-618) 1.7% N/A 4 92% 129 N/A N/A Table 3-6 Physical properties of fine aggregate Fineness Modulus SSD Specific Gravity Apparent Sp ecific Gravity Bulk Specific Gravity Absorption 2.30 2.644 2.664 2.631 0.5% Table 3-7 Physical properti es of coarse aggregates Aggregate SSD Specific Gravity Apparent Specific Gravity Bulk Specific Gravity Absorption Miami Oolite 2.431 2.541 2.360 3.03% Stalite 1.55 6.60% Georgia Granite 2.82 2.85 2.80 0.58%

PAGE 62

63 0 10 20 30 40 50 60 70 80 90 100 #4#8#16#30#50#100#200 Size of SieveCumullative passing Percentage (%) Figure 3-1 Gradation of fine aggregate (Godenhead sand) 0 10 20 30 40 50 60 70 80 90 100 1.5"1"0.5"4#8#200# Size of SieveCumullative Passing Percentage (%) Figure 3-2 Gradation of coarse a ggregate (Miami Oolite limestone)

PAGE 63

64 0 10 20 30 40 50 60 70 80 90 100 1.5"1"0.5"4#8#200# Size of SieveCumullative Passing Percentage (%) Figure 3-3 Gradation of coarse aggregate (Georgia granite) 0 10 20 30 40 50 60 70 80 90 100 1.5"1"0.5"4#8#200# Size of SieveCumulative Passing Percentage (%) Figure 3-4 Gradation of light weight aggregate (Stalite)

PAGE 64

65 Figure 3-5 Compulsive Pan Mixer The procedures to fabricate cylindric al specimens were given as follows: According to mix proportion desi gn, measure out the coarse a ggregate, fine aggregate, cement, mineral admixtures, water, high ra nge water reducer, air entraining agent. Place coarse aggregate and fine aggregate into the pan mixer to mix for about 30 seconds. Place two thirds of the water t ogether with the air-entraining admixture into the mixer and mix for 1 minute. Place cement, mineral additives, such as slag or fly ash, as well as certain amount of highrange water reducer into the pan mixer and mix for 3 minutes, followed by a 2-minute rest, then, followed by a 3minute mixing. Perform a slump test (according to ASTM C143) to determine whether or not the target slump has been reached. If the target slump is not satisfied, add so me more water-reducing admixture instead of water to adjust slump of fresh concrete. In doing so, we can assure the design strength of concrete will not be affected by adding extra water into concrete, which will change the water to cementitious material ratio. Re-mix the fresh concrete for two more minut es. Then, perform another slump test to check if the target slump has been reached. Re peat this procedure until the target slump is achieved.

PAGE 65

663.3.2 The Procedure to Fabricate Specimens After the mixing procedure is completed, place the fresh concrete into "12"6 plastic cylinder molds. Then two different procedures will be taken to consolidate the fresh concrete inside plastic cylinder molds. The first one is that, if the slump of the fr esh concrete is less than 7 inches, fill each cylinder mold to one third of its height, and place the mold on a vibrating table for 45 seconds. Then fill the mold to another one third of its he ight, and place the mold on the vibrating table for 45 seconds. Then fill the mold fully, and place the mold on the vibrating table for 45 seconds. In addition, for the mixtures without any slump valu e, the vibrating time to consolidate concrete should be increased, or the vibrati ng intensity should be adjusted. The second one is that, if the slump is more than 7 inches, fill each cylinder mold in three layers, and rod each layers manually 25 times, as specified in ASTM C31. In doing so, we can assure that the mixtures with low slump value can be well-compacted, while the mixtures with very high slump value will not be segregated due to over-consolidation. After consolidation, finish th e surface of each concrete spec imen with a trowel, and cover the top of the cylinder with a plastic lid to k eep moisture from evaporating. Then, allow the concrete to be cured in the cy linder molds for 24 hours before demolding. But, for concretes with very low compressive stre ngth after 24 hours, allow another 24 hours of curing in the mold before demolding. At last, set the demolded concrete specimens in the standard moist curing room for the specified curing time until testing. 3.4 Curing Conditions for Concrete Specimens The concrete specimens for compressive strength test, split tensile strength test, and elastic modulus test were cured in standard moist room until the age to be tested. Two different curing

PAGE 66

67 conditions were applied to the concrete specim ens of Mix-1F to Mix-10LS for shrinkage and creep tests. The first condition is to cure the concrete specimens fo r 7 days in the moist room and followed by room condition for another 7 days. The second one is to cure the concrete specimens for 14 days in the moist room and followed by room condition for another 14 days. But, only one curing condition wa s applied to Mix-2GF, Mix3GF, Mix-5GS and Mix-7GS, i.e.14 days in moisture room, and then in room condition for another 14 days. 3.5 Tests on Fresh Concrete In order to obtain concrete mixtures with uniform quality, ASTM standard tests, as shown in Table 3-8, on fresh concrete were perf ormed and described in detail as follows: Table 3-8 The testing programs on fresh concrete Test Slump Air Content Unit We ight Setting Time Temperature Test Standard ASTM C143 ASTM C 173 ASTM C138 ASTM C403/C 403M ASTM C 1064 Slump test Slump test was performed in accordance with ASTM C143 standard. The slump value was used to evaluate the consistency of fresh concrete. Air content test Air content test was carried out in accordan ce with ASTM C 173 standard. The volumetric method was employed for this test. Unit weight test The procedures of ASTM C138 standard was followed in running the unit weight test. This test was carried out to verify the density of concrete mixtures for quality control. Setting time test ASTM C403/C 403M standard was followed to perform the setting time test. The mortar specimen for the setting time test was obtained by wet-sieving the sel ected portion of fresh concrete through a 4.75mm sieve. The pr octor penetration probe was employed for running this test. In this test, the initial se tting time is determined when the penetration resistance equals 500 psi, and the final setting time is determined when the penetration resistance reaches 4000 psi.

PAGE 67

68 Temperature test Temperature of the fresh concrete was determined in accordance with ASTM C 1064 standard. This test was used to ensure th at the temperature of the fresh concrete was within the normal range, and that there was no unexpected condition in the fresh concrete. A digital thermometer was used to monitor the temperature of concrete. The properties of the fresh concrete for each of the ten mixtures are presented in Table 3-9. As can be seen from Table 3-9, the slump values of all the concrete mixtur es fell in the range of target slump value other than Mix-2F. The replic ated Mix-2F had a slump value higher than the target value. Also, the air contents of all the c oncretes were in the range of designed target value other than Mix-2F and Mix-5S, which had air content slightly higher than the maximum target value. Table 3-9 Properties of fresh concrete Setting Time Mix Number Slump (in) Target slump (in) Air Content (%) Target Air Content (%) Unit Weight (lbs/yd3) Initial Final Mixture Temperature (F) Mix-1F 7.75 /9.75* 7.5~10.5 1.50 /1.25* 1.0~5.0 143.1 /145.5* 7h 0min 8h 50min 80/81* Mix-2F 7.50 /4.25* 1.5~4.5 7.30 /4.50* 2.4~5.6 133.4 /137.7* 2h 50min 4h 35min 79/73* Mix-3F 1.50 /2.00* 1.5~4.5 1.60 /2.50* 1.0~6.0 145.7 /143.9* 4h 55min 7h 15min 79/76* Mix-4F 3.00 /3.00* 1.5~4.5 1.30 /2.00* 0.0~4.0 142.6 /143.8* ----74/74* Mix-5S 7.25 /9.00* 7.5~10.5 6.80 /3.75* 1.0~5.0 136.9 /141.6* ----81/78* Mix-6S 3.50 /5.50* 4.5~7.5 3.40 /2.25* 1.0~5.0 143.4 /141.4* 3h 10min 4h 55min 79/81* Mix-7S 4.00 /5.75* 1.5~4.5 5.50 /5.50* 1.0~6.0 138.8 /138.0* ----77/79* Mix8S 2.75 /3.00* 1.5~4.5 5.30 /3.75* 1.0~6.0 138.9 /140.4* ----80/76* Mix-9LF 3.75 /2.50* 1.5~4.5 5.20 /3.00* 3.0~6.0 116.9 /117.78 5h 35min 7h 20min 79/80* Mix-10LS 3.50 /2.75* 1.5~4.5 5.50 /5.25* 1.0~6.0 111.6 /109.3* 7h 45min 10h 0min 77/78* Mix-2GF 4.50 1.5~4.5 7.40 2.4~5.6 144.9 ----78 Mix-3GF 2.50 1.5~4.5 1.50 1.0~6.0 150.1 ----79 Mix-5GS 6.50 7.5~10.5 5.50 1.0~5.0 145.8 ----76 Mix-7GS 2.25 1.5~4.5 3.80 1.0~6.0 147.3 ----74 From first phase study.

PAGE 68

693.6 Tests on Hardened Concrete Routine ASTM standard tests on the hardened concrete specimen s are given in Table 3-10. Table 3-10 The testing progr am on hardened concrete Test Compressive Strength Splitting Tensile Strength Elastic Modulus Shrinkage Creep Test Standard ASTM C 39 ASTM C 496 ASTM C 469 Described in this chapter Described in this chapter 3.6.1 Compressive Strength Test Compressive strength test were performed on all the concrete mixtures investigated in this study. Through the compressive strength test, the strength development ch aracteristics of the concretes typically used in Flor ida can be obtained. Furthermore, the results from compressive strength tests can be used to calibrate the prediction equation given by ACI 209R Code so that a reliable prediction equation can be obtained. The test procedure of ASTM C 39 standard was followed for compressive strength test. For each concrete mixture, three replicate "12"6 cylindrical specimens were tested for their compressive strength at the age of 3, 7, 14, 28, 56, and 91 days, with a total of 18 specimens tested. Before testing, both ends of concrete cylinders were ground in order to support the load uniformly. The loading rate was controlled at 100 0 lbf per second. Two t ypical failure modes in the compression test are (1) column failure, and (2 ) shear failure. These two failure modes are shown in Figure 3-6. The compressive strength of the test specime n is calculated by dividing the maximum load attained from the test by the cross-sectional area of the specimen, as shown by the following equation: 2 4 2 D i p r i p i f (3-1) Where

PAGE 69

70 if is ultimate compressive strength of cylinderiin psi; ip is ultimate compressive axial load applied to cylinderiin lbs; D is diameter of cylinder specimen in inch. The average value of compressive strength fr om three cylinders will be taken as the compressive strength of the concrete. Figure 3-6 Typical failure modes of conc rete cylinders in compression test 3.6.2 Splitting Tensile Strength Test (or Brazilian Test) Splitting tensile strength test is simple to perfor m than other tensile tests, such as flexural strength test and direct tensile test. The strength determined from splitting tensile test is believed to be close to the direct tensile strength of concrete. In this study, the testing procedure of ASTM C 496 standard was followed in running the splitting tensile strength test. A "12"6 cylindrical specimen, which is identical to that used for co mpressive strength test, wi th four lines drawn on the sides of specimen to mark the edges of the load ed plane to help align the test specimen before the load was applied, is placed with its axia l horizontally between the platens of a testing machine. Figure 3-7 shows the loading configurati on for this test. As shown in Figure 3-7, two

PAGE 70

71 strips of plywood as packing material, 3mm th ick and 25mm wide, are interposed between the cylinder and the platens so that the force applie d to the cylinder can be uniformly distributed. Then, the load will be applied and increased unt il failure by indirect tension in the form of splitting along vertical diameter takes place. Figure 3-7 Loading configurati on for splitting tensile test The splitting tensile strength of a cylinder specimen can be calculated by the following equation: Dl i p i T 2 (3-2) Where T splitting tensile strength of cylinder in psi; ip maximum applied load to break cylinder in lbf. llength of cylinder in inch; D diameter of cylinder in inch. The splitting tensile strength of concrete will take the average value of splitting tensile strengths of three cylinders. Due to the sensitivity and susceptibility of th e splitting tensile strength to the effects of internal flaws, such as voids, the results of some splitting tens ile strength tests may be unusually low and may need to be discarded. For this reason, five extra c oncrete cylinders were prepared for use in repeating this test if needed. "6 "12 Plywood

PAGE 71

72 At last, the same curing conditions as those for the compressive strength test were used for the splitting tensile strength test. Three replic ate specimens were tested at each of the curing times, which were 3, 7, 14, 28, 56, and 91 days. A total of 18 specimens per concrete mixture were tested for splitting tensile strength. 3.6.3 Elastic Modulus Test The testing procedure of ASTM C 469 standa rd was followed to determine the elastic modulus of the concrete specimens. In this meth od, the chord modulus of elasticity of concrete cylinders is determined when a compressive lo ad is applied on a concrete cylinder in the longitudinal direction. A strain gage will be attached on the concrete cylinder to measure the deformation of the concrete cylinder during a compression test. Th e load and deformation data were recorded by means of a computer data acquisition system. A MTS machine, as shown in Figure 3-8, controls the loading rate by controlling displacement automatically. Prior to the test for modulus of elasticity, one of the three concrete cylinders was broken first to determine the compressive strength of co ncrete in accordance with ASTM C39 standard. Then, 40% of ultimate compressive strength of concrete specimen was applied on the other two concrete cylinders to perform the elastic modul us test. The cylinders for the modulus of elasticity test were loaded and unloaded three times. Then, the data from the first load cycle were disregarded. The average value from the la st two load cycles was recorded as the elastic modulus of the concrete. Since the elastic modulus of concrete will vary with the age of concrete, the elastic modules of concrete at the ages of 3, 7, 14, 28, 56, and 91 days were evaluated. Throughout the test, the ambient te mperature and relative humidity were maintained at 73 F and 100%, respectively.

PAGE 72

73 Figure 3-8 MTS system for elastic modul us and compressive strength test 3.6.4 Shrinkage Test For the concrete mixtures with either Miami Oolite limestone aggregate or Stalite lightweight aggregate, six "12"6 concrete cylinders were made to evaluate their shrinkage behavior under two distinct curing conditions. Thr ee cylinders were cured for 7 days in a moist room, and then followed by a room condition curing for another 7 days. Another three cylinders were cured for 14 days in a moist room, and then cured for another 14 days in room condition. For concrete mixtures with Georgia granite aggregate, their shri nkage behaviors were investigated under just one curing condition, i.e. moist curing for 14 days, followed by curing in room condition for 14 days. Three pairs of gauge points, which were spaced 10 inches apart, were placed on each of concrete cylinder. A gauge-point guide was used to position the gauge points on the plastic cylinder mold before the concrete was cast. Figu re 3-9 shows a picture of the concrete with the gauge points attached on them after the molds have been removed.

PAGE 73

74 Figure 3-9 Cylindrical specimen with gage points installed A digital mechanical gauge was used to meas ure the change in the distance between the gage points as the concrete cyli nder shrinks. The digital mechan ical gauge has a resolution of 0.0001 in. Three sets of measurements were taken from each specimen. A total of nine sets of measurements were taken from the three replicate specimens for each concrete mixture. Measurements were taken every day in the first two weeks, and then once a week up to three months. The initial distance between the gauge points was measured immediately after required curing time was fulfilled. Then, the shrinkage test was run under the condition of the temperature of 73 F and 50% relative humidity. The shrinkage strain was taken as the average of the nine readings from the three replicat e cylinders, and can be expressed as follows: 9 1 0 ) 0 ( 9 1 i l l i l sh (3-3) Where il Measured distance between ith pair of gage points

PAGE 74

75 0l Original distance between ith pair of gage points measured immediately after demoded.

PAGE 75

76 CHAPTER 4 CREEP TEST APPARATUS DESIGN AND TESTING PROCEDURE 4.1 Introduction This chapter describes the design of the creep te st apparatus, and its auxiliary tools, which include a gage-point positioning guide for positi oning gage points on a creep test specimen, and an alignment frame for aligning the specimens in a vertical direction. The creep testing procedures are also described in detail in this chapter. 4.2 Creep Test Apparatus 4.2.1 Design Requirements of Creep Test Apparatus In order to carry out the creep test program, a simple creep test apparatus was designed to satisfy the following design requirements: Creep test apparatus should be capable of applying and maintaining the required load on specimen, despite of any change in the dimension of the specimen. The bearing surfaces of the header plates sha ll not depart from a plane by more than 0.001 inch to insure even pressure distri bution on the concrete test specimens. Several specimens can be stacked for simultaneous loading so that more measurements can be made, and the reliability of test results will be increased by taking average of all the measurements. The height between two header plates shall not exceed 70 inches. If the height between two header plates is over 70 inches, the a pparatus will not be easily operated manually. Also, if the total height of the stacked test specimens is very high, the specimens may buckle easily under load. The applied load should be controlled so that it will vary by less than 2% of the target applied load. Means shall be provided to make sure that concrete specimens are centered properly and vertical. The designed creep test apparatus, which is spring supported system, is shown in Figure 41. The detailed design of creep apparatus used in this study is presented as follows.

PAGE 76

77 4.2.2 Design of Creep Apparatus 4.2.2.1 The determination of the maximum capacity of the creep Apparatus In this study, the maximum design capacity of creep apparatus was determined according to the maximum compressive streng th (10 ksi) of concrete mixtur es commonly used in Florida. Creep test was run under the loading condition of 50% of compressive strength of concrete on "12"6 cylindrical concrete specimens. Thus, the ma ximum load applied to the creep frame can be computed as: lbf P 1413003 100005.02 max If a "8"4 cylindrical concrete specimen is used, th e creep test can be run on the concrete with compressive strength as high as 22 ksi. 4.2.2.2 The design of springs The spring constant of the larger spring (1k) was selected as 9822 lbf/in, while the spring constant of the smaller spring (2k) was selected as 3314 lbf/in. The maximum travel distance ( ) for both springs is 1.625 in. If nine sets of springs are used, the maximum load (springP ) that the springs can hold can be calculated to be: OK Plbf kk Pspringmax 5 211092.1 9 Thus, the spring capacity is ok. It is of importance to mention that the desi gn maximum travel distance of spring can not be more than the maximum travel capacity of the springs in order to maintain the load on specimen constant, and keep the frame stable.

PAGE 77

78 Figure 4-1 Creep test apparatus 1 1 1.25in 1.125in 1.5in 1in 36in 1in 8.25in 1in 10in 18in 12in 12in 18in 1.5in 1in Hydraulic Jack Load Cell Springs Concrete Cylinder Gauge Circular Steel Plate Circular Steel

PAGE 78

79 4.2.2.3 Design of header plate Figure 4-2 Boundary conditions used for finite element analysis In order to apply load uniformly to the test specimens, the deflection of header plate should not deviate too much for a plane surface when th e specimens are loaded. The required thickness of the header plates was determined using a fin ite element analysis. The steel plate was modeled as an isotropic elastic material with an elastic modulus of 29,000 ksi and Poissons ratio of 0.30, which are typical properties of st eel. The plate was modeled as fi xed from rotation about the x, y and z axis along the four boundary lines along the four holes on the steel plate as shown in Figure 4-2. The loading zone was modeled as a circular area identical to the cross sectional area of a 6inch diameter concrete cylinder. The maximum lo ad used in the analysis had a pressure of 5000 psi, which is 50% of the maximum compressive stre ngth of concrete investigated in this study. 12in 6in 6in 1.25in 6 in Loading Zone

PAGE 79

80 Figure 4-3 Finite element mesh used in the header plate analysis Figure 4-4 Contour plot of deflection of header plate The finite element mesh used in the analysis consisted of triangle elements and rectangular elements as shown in Figure 4-3. The header pl ate with a thickness of 1.5 inches was analyzed. The deflection contour plot is s hown in Figure 4-4. As we can s ee from Figure 4-4, the deflection from center of header plate to the position 3 inches away fr om center changes from 0.00408 to 0.0033 inch. In other words, if the test specimens ar e loaded to a maximum pressure of 5,000 psi, the deflection of steel plat e will differ by less than 0.00078 inch, which is less than 0.001 inch. Thus, a header steel plate with a thickne ss of 1.5 inches was determined to be adequate and selected for use.

PAGE 80

81 4.2.2.4 Determination of the size of steel rod When the concrete specimens are loaded in the creep frame, each of the four steel rods will carry one quarter of tota l load. The steel rods are 1.125 in. in diameter and are made of highstrength alloy steel with yield strength of 105,000 psi. If th e concrete specimens are loaded up to the maximum capacity of the creep apparatus of 141,300 lbf, the maximum stress in the steel rods would be equal to: psi 35556 5625.04 1413002 This maximum possible stress in the steel rods is less than half of the yield strength of the steel rod, which is 105,000 psi. Thus, the select ed steel rod meets the design requirements. 4.2.2.5 Stress relaxation due to the deflection of header plate and creep of concrete When the full capacity of creep frame is used, the total stress released due to the plate deflection can be approximated as follows: pounds k Ptotal deflection relaxed485913136 0041.0 Where deflection is the maximum deflection of header plate, and springk is the elastic constant of spring. While according to the design requirement, the allowable load relaxation is pounds 282602.0141300 In addition, since partial load will be relaxed due to the creep of concrete, the applied load to the concrete specimen should be adjusted in or der to keep the load th e same as the initially applied one. To have an error of less than 2,826 lbf in the app lied load, the following inequality has to be satisfied: lbf lbf ktotalcr2826 485 36 Solving the above inequality, we obtain that

PAGE 81

82 0006.0 cr This means that the applied load should be adjusted at every 0.0006 increment of creep strain. Otherwise, the load relaxed would be more than 2826 lbf, the allowable maximum load relaxation. 4.3 Design of Gage-Point Positioning Guide Three pairs of gage points with a gage distan ce of 10 inches are to be placed in each test concrete specimen. A gage-point positioning gui de, as shown in Figure 4-5, was designed for use in positioning the gauge-points on the plastic cylinder mold. By inserting a "12"6 cylinder mold into gage-point position gu ide and tightening the six screws on the guide, the precise locations for the three pairs of gage points, wi th a gage distance of 10 inches, can be marked conveniently on the mold. Three lines of gage points are uniformly distributed with 120 angle along the periphery of specimen. The use of the gage positioning guide is of great importance because the maximum travel distance of mechanical strain gage is 0.4 in. The mechanical strain gage can not be used to measure a distance of mo re than 10.4 inches. Thus it is very important that the two gage points be place at an exact distance of 10 inches from one another. Figure 4-6 shows a picture of the gauge-position guide. Figure 4-7 shows a picture with a plastic cylinder inside the gauge-position guide. 4.4 Design of Alignment Frame An alignment frame was designed and construc ted to be used to align the concrete specimens in a vertical direction when they are placed in the test frame. Figure 4-8 shows the design of the alignment frame. The alignment fram e consists of one piece of angle steel and one piece of channel steel with three pieces of "10"2"5.0 steel plates welded on them respectively. They are connected together by using 6 steel rods The use of the alignment frame is described in creep testing procedure.

PAGE 82

83 Figure 4-5 Design of Gage-point positioning guide 10 6.05 120o 120 o 120 o

PAGE 83

84 Figure 4-6 Gauge position guide Figure 4-7 Plastic cylindrical mold inside gauge position guide

PAGE 84

85 4.5 Mechanical Strain Gauge A mechanical strain gauge, as shown in Fi gure 4-9, was used to measure the distance change between two gauge points. The instrument frame is made of aluminum alloy and has five master settings of 2", 4", 6", 8", and 10" that ar e easily set for gauging. The digital indicator has a minimum graduation of 0.0001". In this study, the master setting of 10" was selected so that the mechanical strain gage is suitable for the measur ement of longitudinal strain to the nearest 10 millionths. In addition, the effective range of displacement measurement is 0.3". 4.6 Other Details on Creep Apparatus For each test frame, three "12"6 cylindrical specimens are pla ced on top of one another and tested under the same load. The load is applied by means of an electronic hydraulic jack (with a maximum capacity of 200,000 lbs) and monitored by a load cell with a digital readout indicating the load applied. Th e load cell has a capacity of 200 kips, and the minimum readable digit of 10 pounds. When the desired load is reac hed, the nuts on the threaded rods is tightened so that they are snugly pressing against the plate underneath the hydr aulic jack so as to hold the plate in that position, and thus holding the applied load. After th e nuts are positioned properly to hold the applied load, the jack and the load cell ca n be removed from the test frame and used to load another test frame. The springs at the bottom of the creep frame help to maintain the balance of creep frame as well as a constant load on the sp ecimens despite any change in its length, as the concrete specimens creep under load. Up to 9 sets of springs can be used in this test frame. Figure 4-10 shows the positions of the springs in the test frame. Each set of springs consists of a smaller spring sitting inside a larger spring. In addition, the springs s hould be manufactured so that both ends of spring should be flatted, and nine sets of spri ngs should have the same height, and positioned symmetrically to keep load distribution evenly. In doing so there is no spherical bearing device needed to guarantee the load to be evenly transferred to the specimens.

PAGE 85

86 As the concrete specimens are loaded in the creep frame, the rectangular steel plates, which are at the top and bottom of the test specimens, are deflected slightly. To keep the loading surfaces flat and the test specimens vertical when the load is applied, tw o 1-inch thick circular steel plates with a diameter of 6 inches are plac ed on the top and bottom of the stack of concrete test specimens, as shown in Figure 4-1. Both surf aces of the circular plate should be polished to avoid of any uneven pressure on the concrete cylinder. 4.7 Creep Testing Procedure 1. Install gauge points on plastic cylindrical molds using the Gauge Position Guide. Each creep test specimen contains three pairs of gage points installed on concrete cylinder using Gauge position guide, which are placed 10 inches apart from each other. 2. Place the fresh concrete in the plastic cylinder molds. Place the fresh concrete into plastic cylinder in three layers. Consolidate each layer with 45 seconds of vibration on a vibrating table. After consolidation, the top su rface of concrete should be finished gently. This is a very important detail in making sp ecimen to avoid cracki ng around gauge insert as shown in Figure 4-11. If too much pressu re is applied to finish the surface, gauge inserts may be pushed downward because the plastic cylinder is not very stiff and can not keep the gauge inserts from being pushed dow nward. Once pressure is released, the gauge insert will return to its original pos ition, while concrete can not because plastic deformation can not be recovered. Thus, so me space between gauge insert and concrete will be created and it will affect the measurement. 3. Demold the concrete specimens after 24 hours of curing. Place the specimens in a moist room to cure for the required time. 4. Grind both end surfaces of each concrete cylinder. Both end surfaces of specimen should be ground in order to make them even, as shown in Figure 4-12. 5. Cap both ends of each cylinder using sulfur mortar to make end surfaces smooth and even. 6. Using the alignment frame designed for this study to stack the three replicate specimens vertically on top of one another. 7. Put two circular plates on top of concrete cy linder as well as at the bottom of concrete cylinders.

PAGE 86

87 Figure 4-8 Schematic of alignment frame design 0.5in 0.5in 12.00in 1.5in 1.75in 2.00in 2.00in 12.00in 12.00in 5.00in 0.19in 0.19in 0.5in 0.5in 3.00in 8.00in 4.00in 4.00in 0.5in 10.00in

PAGE 87

88 Figure 4-9 Mechanical gauge Figure 4-10 Positioning springs on the bottom plate 6in 12in Large spring Small spring 12in 6in Outside 5.50in Inside 2.94i

PAGE 88

89 Figure 4-11 Cracking around gauge insert Figure 4-12 Concrete cylinder with both end surfaces ground 8. Adjust the creep frame and concrete specimens to make sure the specimens are centered and vertical. The creep frame can be adjust ed through moving the h eader plate back and forth with the nuts on the top of the plate. As shown in Figure 4-13, the centers of header plate and the plate on the top of springs are marked. On each plate is also marked a 3inch diameter with 8 mark points along the boun dary of the circle. If the concrete column consisting of three cylinders is placed so that it lines up with the circ les on the header and the bottom plates, then the concrete cylinders are centered and vertical. 9. After the concrete specimens are center ed, turn the nuts supporting the header plate downward at least 1.65 in. away from the bottom of header plate to avoid the header plate contacting with the nuts once load is applie d. Then, tighten the four nuts on the top of header plate slightly to hold the centered concrete specimens. Pressure applied while finishing Space Created Gauge Insert

PAGE 89

90 Figure 4-13 How to center the specimens into creep frame 10. Set up a hydraulic jack and load cell in the creep frame, and check the position of hydraulic jack to make sure that it is co-axial with concrete specimens in order to avoid loading the concrete specimen s eccentrically. As shown in Figure 4-14, in order to make the hydraulic jack co-axial w ith concrete specimens, the cen ter of the header plate has also been marked on the top side. A circle with diameter identical to the diameter of jack cylinder has also been drawn on top of the header plate, with 4 marks hammered along the boundary of the circle 11. As shown in Figure 4-15, check the plate on th e top of load cell to make sure that the plate is level. Then, tighten slightly th e four steel nuts holding the top plate. 12. Preload the frame up to 500 lbf to properly se at the concrete test specimens in the creep frame. 13. Take the initial measurements, which are th e initial distance between two gauge points. 14. Apply the load through the electr onic hydraulic jack up to the ta rget load. It is strongly recommended to use electronic hydraulic jack because of several advantages in using electronic hydraulic jack. Firstly, by usi ng electronic hydraulic ja ck, the load can be applied to the loading frame continuously. S econdly, since the elec tronic hydraulic jack can apply load on the cylinder within 1 minute, the instantaneous measurements can be taken within seconds immediat ely after the loading procedur e was completed. Thus, the instantaneous measurement taken in this way is very close to the true elastic deformation. Thirdly, in using the electr onic hydraulic jack, the dynamic effect, which can cause the =6in Mark Point Circular Plate Header Plate 1.65in

PAGE 90

91 cylinders to break easily, can be avoided. In a ddition, less effort is needed to load frame in comparison with using manual hydraulic ja ck, which takes hundreds of pushes to reach the desired load level. Figure 4-14 How to center th e hydraulic jack cylinder Figure 4-15 Leveling the plat e on the top of load cell 15. Immediately after the target load is reached, tighten the four nuts on the top of the header plate to hold the load on the specimens. Jack Cylinder Load cell Mark Point Jack Cylinder

PAGE 91

92 16. Take instantaneous measurements using the digital mechanical gage immediately after loading. Then take the measurements in 1 hour, 3 hours and 6 hours. Then every day in the first two weeks, and then once a week un til 91 days, and then once a month if tests were kept going. 17. Adjust load at every 0.0008 increment of creep strain to keep the lo ad loss due to creep relaxation less than 2% of total load applied at the beginning. It deserves to emphasize again that it is important to take the first set of readings as quickly as possible in order to obtain a more accurate instantaneous deformation of the concrete. Otherwise, substantial early creep deformation may have taken place before the initial readings can be taken. The first set of readings can be taken within 3 minutes. The creep strain was calculated by subtracting th e shrinkage strain from the total strain as follows: ) 9 1 )(0 )(0 9 1 )(0 )(0 ( 9 1 i S i l S i l S i l i T i l T i l T i l STC (4-1) Where C Creep strain of concrete T The sum of creep strain and shrinkage strain S Shrinkage strain of concrete TilThe measurement taken from the thi pair of gage points for creep test Til)(0The initial length of the thi pair of gage points for creep test SilThe measurement taken from the thi pair of gage points for shrinkage test Sil)(0The initial length of the thipair of gage points for shrinkage test iNo. of pair of gage points from 1 to 9

PAGE 92

93 The creep coefficient, which is used in conc rete structure design, is calculated by taking the ratio of creep strain of the concrete at the testing age to elastic strain of concrete at the same curing age. It can be expressed as follows: E C cr C (4-2) Where crC Creep coefficient C Creep strain of concrete E Elastic strain of concrete Creep modulus, EC, is computed dividing the applied stress by the total strain without including shrinkage strain, as shown by Equation 4-3. cE c E (4-3) 4.8 Summary on the Performance of the Creep Apparatus The creep apparatus designed in this study is capable of applying and maintaining the required load on the test specimens. Three specim ens can be stacked for simultaneous loading. The unevenness of the deflection of bearing surface of the header plates is less than 0.001 in. and the pressure distribution on the concrete specimens varies by less than 0.026%, or 1.5 psi. Load can be applied to a precision of 10 lbs, as a load cell with resolution of 10 lbs is used control the applied load. The mechanical gauge used is able to measure longitudinal strain to a precision of 0.00001. Strains are measured on three gage lines spaced uniformly around the periphery of the specimen. An electronic hydraulic pump system is us ed to apply load to the creep frame. This

PAGE 93

94 enables the loading process to be done in second s, and instantaneous strains can measured from creep test within a short time after loading. The gauge point position guide, which has b een designed to position gauge points on a plastic cylindrical mold, is a very effective and important auxiliary tool in preparation of test specimens. It enables the placement of gauge points at accurate locations on the test specimen so that the maximum travel distance of mechanical gauge will not be exceeded and measurement error can be reduced. The alignment frame, which has been designed to align concrete specimens vertically in the creep frame, makes the job of stacking three concrete specimens together for testing possible. Experimental results indicate that creep apparatus designed in this study is effective, reliable and practical. It can be used to run creep test on conc rete with a maximum compressive strength up to 10,000 psi if "12"6 cylinder specimens are used. If "8"4 cylinder specimens are used, the maximum compressive strength of th e concrete can be as high as 22,000 psi.

PAGE 94

95 CHAPTER 5 ANALYSIS OF STRENGTH TEST RESULTS 5.1 Introduction This chapter presents the results from comp ressive strength, splitti ng tensile strength and elastic modulus tests on the 14 concretes mixes ev aluated in this study. The effects of various factors on strength are discussed. The predic tion equations establis hing inter-relationship between compressive strength and splitting tensil e strength are given. The prediction equations relating compressive strength to elastic modulus are also presented. 5.2 Results and Analysis of Compressive Strength Tests The average compressive strengths at various curing times of the fourteen concrete mixes evaluated are presented in Table 5-1. The individual compressive strength values are shown in Table A-1 in Appendix A. Table 5-1 Compressive strength of th e concrete mixtures evaluated (psi) Age of Testing (days) Mix Number W/C Fly ash Slag 3 7 14 28 56 91 Mix-1F 0.24 20% 8077 8572 8993 9536 10771 11267 Mix-2F 0.33 20% 4077 4658 6028 6506 6838 7607 Mix-3F 0.41 20% 5289 6470 7567 8241 8449 9426 Mix-4F 0.37 20% 5712 6919 7114 7236 8996 9271 Mix-5S 0.33 50% 5554 7235 8248 8832 9139 9456 Mix-6S 0.36 50% 6375 7699 8587 9111 9529 9661 Mix-7S 0.41 70% 4324 5374 5927 6392 6794 6917 Mix-8S 0.44 50% 4795 6114 6939 7525 8119 8208 Mix-9LF 0.31 20% 3039 3941 5136 5929 6690 6961 Mix-10LS 0.39 60% 1467 2191 2937 3744 4312 4727 Mix-2GF 0.33 20% 3885 4952 5807 6469 6952 7201 Mix-3GF 0.41 20% 3818 5151 6137 7262 7782 8041 Mix-5GS 0.33 50% 2961 4692 5692 7008 7854 8105 Mix-7GS 0.41 70% 2267 4303 5222 6612 6741 7233 5.2.1 Effects of Water to Cement Ratio and Water Conten t on Compressive Strength In engineering practice, the st rength of concrete at a given age and cured in water at a prescribed temperature is assumed to depend on primarily on water to cementitious materials ratio and the degree of compaction. In this study, for the eight selected concrete mixtures using

PAGE 95

96 Miami Oolite limestone aggregate, the effects of water to cementitious materials ratio on compressive strength at ages of 28 days and 91 days are shown in Figure 5-1 and Figure 5-2 respectively. The graph of compressive strength versus water to cementitious materials ratio is approximately in the shape of a hyperbola. Compre ssive strength tends to decrease as water to cementitious materials ratio increases. Water content is another important factor infl uencing the strength of concrete because the higher the water content, the more porous the hardened concrete tends to be. As shown in Figure 5-3 and Figure 5-4, compressive strength of concrete decreases dramatically as water content increases. 0 2000 4000 6000 8000 10000 12000 14000 16000 00.10.20.30.40.50.6 Water to Cementitious Materials RatioCompressive Strength at 28 days Figure 5-1 Effects of water to cementitious materials ratio on compressive strength at 28 days

PAGE 96

97 0 2000 4000 6000 8000 10000 12000 14000 16000 00.10.20.30.40.50.6 Water to Cementitious Materials RatioCompressive Strength at 91 days Figure 5-2 Effects of water to cementitious materials on compressive strength at 91 days 0 2000 4000 6000 8000 10000 12000 14000 16000 220230240250260270280290 Water Content (lbs/yard3)Compressive Strength at 28 days (psi) Figure 5-3 Effects of water content on compressive strength at 28 days

PAGE 97

98 0 2000 4000 6000 8000 10000 12000 14000 16000 220230240250260270280290 Water Content (lbs/yard3)Compressive strength at 91 days (psi) Figure 5-4 Effects of water content on compressive strength at 91 days 5.2.2 Effects of Aggregate Types on Compressive Strength The influence of coarse aggregate type on compressive strengths of four concrete mixtures is shown in Figures 5-5 thr ough 5-8. Figure 5-5 shows the co mpressive strength development with time for Mix-2F and Mix-2GF containing 20 % fly ash. Both concrete mixtures have identical mix proportions other than the different types of aggregate. Miami Oolite limestone aggregate was used for Mix-2F, and Georgia granite aggregate was used for Mix-2GF. It can be seen that the compressive strength of Mix-2F is comparable to that of Mix-2GF at various curing ages. For Mix-5S and Mix-5GS, the different aggr egate types gave considerable impact to the compressive strength. As can be seen from Figur e 5-6, Mix-5GS using Ge orgia granite aggregate had very much lower compressive strength than Mix-5S using Miami Oolite limestone aggregate at various ages. The same phenomenon can also be observed from Mix-3F and Mix-3GF, as shown in Figure 5-7, and Mix-7S and Mix-7GS, as depicted in Figure 5-8.

PAGE 98

99 According to the concrete mixtures investigated in this study, the concrete mixtures using Miami Oolite limestone as coarse aggregate deve loped higher compressive strength than those using Georgia granite as coarse aggregate. The cause can be attributed probably to the sh ape of aggregate, surface characteristic and other physical properties such as water absorption. Most of aggregate particles of Georgia granite have elongated and flaky shape, which is not desirable to be used for high strength concrete because flaky particles tend to be oriented in one plane, w ith bleeding water and air voids forming underneath. Thus, the interf acial transition zone between aggregate and hardened mortar may be weaker causing the compressive strength of concrete to be lower. Most of the aggregate particles of Miami Oolite limestone have spherical shape, which is preferred for durable concrete mix because the spherical aggregate particles have lower surface to volume ratio, and they will pack better in a mortar matrix. The surface texture of Georgia granite aggreg ate is very dense and smooth, which may have a disadvantage in devel oping tight interlock between aggr egate and mortar matrix. Miami Oolite limestone has a very rough texture and ap preciable voids on the surface, and thus strong interlock can be formed since the cement slurry can penetrate into those voids. The water inside limestone aggregate can mi grate outward as cement hydration proceeds since the relative humidity gradient will be gene rated between internal aggregate and mortar. This water may possibly provide th e water needed for hydration of th e cement as moisture is lost through evaporation to the environment.

PAGE 99

100 0 1000 2000 3000 4000 5000 6000 7000 8000Compressive Strength (psi) Curing Age (days) Limestone 0407746586028650668387607 Granite 0388549525807646969527201 0 3 7 14285691 Figure 5-5 Effects of coarse aggregate type on compressive strengths of Mix-2F and Mix-2GF 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000Compressive Strength (psi) Curing Age (days) Limestone 0528964707567824184499426 Granite 0381851516137726277828041 03714285691 Figure 5-6 Effects of coarse aggregate type on compressive strength of Mix-3F and Mix-3GF

PAGE 100

101 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000Compressive Strength (psi) Curing Age (days) Limestone 0555472358248883291399456 Granite 0296146925692700878548105 03714285691 Figure 5-7 Effects of coarse aggregate type on compressive strength of Mix-5S and Mix-5GS 0 1000 2000 3000 4000 5000 6000 7000 8000Compressive Strength (psi) Curing Age (days) Limestone 0432453745927639267946917 Granite 0226743035222661267417233 03714285691 Figure 5-8 Effects of coarse aggregate type on compressive strength of Mix-7S and Mix-7GS

PAGE 101

102 5.2.3 Effects of Fly Ash and Slag on Compressive Strength of Concrete Fly ash and slag are used mandatorily in Fl orida mainly for concrete durability purpose. The investigation on their eff ects on the development of compressive strength of concrete mixture is of great importance becau se of significance of their use in concrete. In this study, fly ash was as a cement substitute in an amount of 20% of total cementitious materials by mass, and slag was in an amount of 50%~70% of tota l cementitious materials by mass. The strength development characteristics of fly ash concrete and slag concrete with time were normalized as the ratio of compressive strength at various curi ng ages to the compressive strength at 91 days and the normalized values are presented in Table A-2 in Appendix A. The strength development characteristics of two typical fly ash concretes and two slag concretes are illustrated in Figure 5-9. As can be seen from Figur e 5-9, the fly ash concretes had significant strength gain from 28 days to 91 days, while the slag concretes had already achieved more than 90% of their 91-day strength at 28 days. 0.70 0.75 0.80 0.85 0.90 0.95 1.00 0 20 40 60 80 100 Ages (days)% of 91-day Compressive Strength Mix-1F-Fly ash-W/C=0.24 Mix-3F-Fly ash-W/C=0.33 Mix-6S-Slag-W/C=0.36 Mix-5S-Slag-W/C=0.33 Figure 5-9 Effects of fly ash and slag on compressive streng th of concrete

PAGE 102

103 5.2.4 Prediction of Compressive Strength Development Knowledge of the strength-time relation is of great importance when a structure is put into service, i.e. subjected to full loading condition an d for long time duration. The gain in strength after 28 days can be taken into consideration in design. In some other cases, for instance, in precast or prestressed concrete, or when early rem oval of formwork is required, the strength at early ages needs to be known. According to ACI 209R-5, a general equation for predicting compressi ve strength at a given age has the following form: 28 )( c f t t t c f (5-1) Where in days and are constants, 28cf is compressive strength of concrete at 28 days, and t in days is the age of concrete. Equation 5-1 can be transformed into / )( cu f t t t c f (5-2) Where / is the age of concrete in days at wh ich one half of the ultimate compressive strength of concrete, 'cuf is reached. For the tests using 6 12in cylinders, type I cement and moist curing condition, two constants, the average values of and are equal to 4.0 and 0.85 respectively. The ranges of and in Equation 5-1 and 5-2 for the normal weight, sand lightweight, and all lightweight concretes (using both moist curing and steam curing, and type I and III cement) given by Branson, D.E.; Meyers, B.L.; and Kripanarayanan, K.M[Branson, D.E et al. 1973] are: =0.05 to 9.25, and =0.67 to 0.98. They were obtained from the tests on 88 6 12in concrete cylinders and cited by ACI 209 COMMITTEE REPORT in 1996. As mentioned in ACI 209R-4, the values of and are not applicable to the concretes containing pozzolanic

PAGE 103

104 materials, such as fly ash and slag. Furthermor e, ACI 209R-4 indicates that the use of normal weight, sand lightweight, or all lightwei ght aggregate does not appear to affect and significantly. In this study, regression anal ysis using the form of ACI 209R-5 equation (as shown in Equation 5-1) was performed on the results of compressive strength tests on the 432 concrete cylinders from this study to determine the and values for each mix. Table 5-2 shows the and values for all the mixes from this analysis. The detailed results of this analysis are presented in Table 5-3. Table 5-4 presents the average and values of the different concrete mixes as grouped by aggregate type. Table 5-4 also shows the time ratios 28 ')(c cf tf and ')(cu cf tf at different during times for these different groups of concrete mix in comparison with the corresponding values as predic ted by the ACI-209R equation. As can be seen from Table 5-2, th ere is substantial difference between and values among the different mixes. For the concrete mixtures using Miami Oolite limestone coarse aggregate, the value of varies from 1.1 to 2.6, and its av erage value of 1.89 is significantly lower than 4.0 recommended by th e ACI-209 code; and the value of is in the range of 0.82 to 0.93, and its average value of 0.90 is slightly higher than 0.85 given by the ACI code. This means that the concrete mixes using Miami Oolit e limestone aggregate and fly ash and slag tend to develop strength faster than the concrete mixtures as predicted by the ACI-209R equation. For the concrete mixtures using Geor gia granite aggregate, the value of varies from 2.6 to 5.3, and its average value of 4.12 is close to 4.0 recommended by the ACI code; and the value of is in the range of 0.82 to 0.89, and its aver age value of 0.86 is agreeable with 0.85 given by

PAGE 104

105 the ACI code. Thus, this indicates that the concre te mixtures using Georgi a granite aggregate had similar strength development as predicted by the ACI equation. For the concrete mixtures using the Stalite lightweight aggregate, the average value of is 5.5 and the average value of is equal to 0.78. This indicates that coarse aggregate type can have significant effects on the strength development process. 5.3 Analysis of Splitting Tens ile Strength Test Results The average splitting tensile strengths at vari ous curing times of the fourteen concrete mixes evaluated are displayed in Table 5-5. Th e individual splitting tens ile strength values are shown in Table A-3 in Appendix A. 5.3.1 Effects of Water to Cement Ratio on Splitting Tensile Strength Water to cementitious materials ratio has a significant effect not only on compressive strength, but also on splitting tensile strength. Figure 5-10 and Figure 5-11 show the effect of water to cementitious materials ratio on splitting tensile strength of concre te at 28 days and at 91 days re spectively. They indicate that splitting tensile strength decreases as water to cementitious materials ratio increases. 5.3.2 Effects of Coarse Aggregate Ty pe on Splitting Tensile Strength The effect of coarse aggregate types on splitti ng tensile strength of concrete was evaluated on four concrete mixtures. Mix-2F, Mix-3F, Mi x-5S, and Mix-7S have Miami Oolite limestone as coarse aggregate, and Mix-2GF, Mix-3GF, Mix-5GS, and Mix-7GS ha ve Georgia granite as coarse aggregate. Mix-2F and Mix-2GF, Mix-3F and Mix-3GF, Mix-5S and Mix-5GS, and Mix7S and Mix-7GS have identical mix proportions with the exception that a different coarse aggregate of the same volume was used. As show n in Figures 5-12 through 5-15, the effects of coarse aggregate types on splitting tensile strength of concrete are quite significant. In comparison with Mix-2F, Mix-3F, Mix-5S and Mix7S, the four mixtures using Georgia granite

PAGE 105

106 Table 5-2 Results of regression analysis for prediction of compressive strength development using ACI 209 equation Mix by ACI by ACI Square root of Absolute sum of squares by Modified ACI Equation Square root of Absolute sum of squares by ACI Equation M-1F 1.10 0.90 673 1904 M-2F 2.67 0.89 371 541 M-3F 2.25 0.90 343 792 M-4F 1.57 0.83 676 1571 M-5S 2.04 0.92 67 886 M-6S 1.57 0.94 125 1214 M-7S 1.79 0.92 275 1698 M-8S 2.15 0.91 150 726 M-9LF 4.20 0.82 230 261 M-10LS 6.74 0.74 131 385 M-2GF 2.64 0.89 180 445 M-3GF 3.51 0.88 197 257 M-5GS 4.99 0.82 160 311 M-7GS 5.35 4 0.86 0.85 269 547

PAGE 106

107Table 5-3 Results of regression analysis on the prediction of compressive strength deve lopment using ACI 209 equation Mix Results M-1F M-2F M-3F M-4F M-5S M-6S M-7S 1.098 2.673 2.252 1.573 2.039 1.574 1.792 0.9017 0.8886 0.9043 0.8261 0.9231 0.9363 0.9213 (SE) 0.3482 0.4901 0.3071 0.4732 0.05387 0.08311 0.1261 (SE) 0.03574 0.0344 0.02365 0.04108 0.004384 0.007592 0.01085 (95%CI) 0.2026 to 1.993 1.413 to 3.933 1.463 to 3.042 0.3568 to 2.790 1.901 to 2.178 1.361 to 1.788 1.468 to 2.116 (95%CI) 0.8098 to 0.9935 0.8002 to 0.9770 0.8435 to 0.9651 0.7205 to 0.9317 0.9118 to 0.9344 0.9168 to 0.9558 0.8934 to 0.9492 DOF 5 5 5 5 5 5 5 R 0.9736 0.9801 0.9902 0.9625 0.9997 0.9989 0.9978 ASS 2266000 769806 589302 2168000 22420 73904 75810 Sy.x 673.3 392.4 343.3 658.4 66.96 121.6 123.1 Points Analyzed 7 7 7 7 7 7 7 Table 5-3 Continued Mix Results M-8S M-9LF M-10LS Mix-2GF Mix-3GF Mix-5GS Mix-7GS 2.152 4.203 6.744 2.635 3.512 4.993 5.345 0.9054 0.8239 0.74 0.8916 0.8777 0.815 0.8554 (SE) 0.1427 0.4144 0.5222 0.2175 0.2677 0.2823 0.4698 (SE) 0.01122 0.02191 0.01987 0.0154 0.01618 0.01346 0.02215 (95%CI) 1.786 to 2.519 3.138 to 5.268 5.402 to 8.087 2.076 to 3.194 2.824 to 4.200 4.267 to 5.718 4.137 to 6.552 (95%CI) 0.8765 to 0.9343 0.7675 to 0.8802 0.6889 to 0.7911 0.8520 to 0.9312 0.8361 to 0.9193 0.7804 to 0.8496 0.7984 to 0.9123 DOF 5 5 5 5 5 5 5 R 0.9978 0.9927 0.9949 0.996 0.996 0.9975 0.9941 ASS 112202 263786 85405 151718 193402 128354 251535 Sy.x 149.8 229.7 130.7 174.2 196.7 160.2 224.3 Points Analyzed 7 7 7 7 7 7 7

PAGE 107

108Table 5-4 Values of the constants, and / and the time ratios from Equation 5-1 and 5-2 Concrete ages (days) Time Ratio Type of Curing Cement Type Aggregate type and / 3 7 14 28 56 91 Ultimate in time ACI 209R-4 =4.00 =0.85 0.46 0.70 0.88 1.00 1.08 1.12 1.18 Miami Oolite Limestone =1.89 =0.90 0.65 0.85 0.97 1.00 1.07 1.09 1.11 Granite =4.12 =0.86 0.45 0.69 0.87 1.00 1.07 1.10 1.16 28 ')(c cf tf Moist cured I Stalite =5.50 =0.78 0.38 0.64 0.85 1.00 1.14 1.19 1.28 ACI 209R-4 / =4.71 0.39 0.60 0.75 0.86 0.92 0.95 1.00 Miami Oolite / =2.10 0.59 0.77 0.87 0.93 0.96 0.98 1.00 Granite / =4.79 0.39 0.59 0.75 0.85 0.95 0.95 1.00 ')(cu cf tf Moist cured I Stalite / =7.05 0.29 0.50 0.67 0.80 0.89 0.93 1.00

PAGE 108

109 Table 5-5 Splitting tensile strengths of the concrete mixtures evaluated (psi) Age of Testing (days) Mix Number W/C Fly ash Slag 3 7 14 28 56 91 Mix-1F 0.24 20% 592 628 715 795 834 849 Mix-2F 0.33 20% 408 484 528 542 621 659 Mix-3F 0.41 20% 513 539 562 624 674 731 Mix-4F 0.37 20% 457 520 566 670 759 770 Mix-5S 0.33 50% 442 574 634 689 711 738 Mix-6S 0.36 50% 570 602 648 672 690 718 Mix-7S 0.41 70% 426 473 518 548 590 596 Mix-8S 0.44 50% 372 499 550 633 693 703 Mix-9LF 0.31 20% 350 404 448 490 551 577 Mix-10LS 0.39 60% 212 288 364 405 418 430 Mix-2GF 0.33 20% 352 421 488 529 548 595 Mix-3GF 0.41 20% 382 409 503 561 599 651 Mix-5GS 0.33 50% 282 420 462 525 591 649 Mix-7GS 0.41 70% 245 362 430 504 554 577 0 200 400 600 800 1000 1200 0.10.20.30.40.50.6 Water to cementitious Materials RatioSplitting Tensile Strength at 28 days (psi) Figure 5-10 Effects of water to cement ratio on splitting te nsile strength at 28 days

PAGE 109

110 0 200 400 600 800 1000 1200 0.10.20.30.40.50.6 Water to Cementitious Materials RatioSplitting Tensile Strength at 91 days (psi) Figure 5-11 Effects of water to cement ratio on splitting te nsile strength at 91 days

PAGE 110

111 0 100 200 300 400 500 600 700Splitting Tensile Strength (psi) Curing Age (days) Limestone 0408484528542621659 Granite 0352421488529548595 03714285691 Figure 5-12 Effects of aggregat e type on splitting tensile stre ngth of Mix-2F and Mix-2GF 0 100 200 300 400 500 600 700 800Splitting Tensile Strength (psi) Curing Age (days) Limestone 0513539562624674731 Granite 0382409503561599651 03714285691 Figure 5-13 Effects of aggregat e type on splitting tensile stre ngth of Mix-3F and Mix-3GF

PAGE 111

112 0 100 200 300 400 500 600 700 800Splitting Tensile Strength (psi) Curing Age (days) Limestone 0442574634689711738 Granite 0282420462525591649 03714285691 Figure 5-14 Effects of aggregat e type on splitting tensile stre ngth of Mix-5S and Mix-5GS 0 100 200 300 400 500 600Splitting Tensile Strength (psi) Curing Age (days) Limestone 0426473518548590596 Granite 0245362430504554577 03714285691 Figure 5-15 Effects of aggregat e type on splitting tensile stre ngth of Mix-7S and Mix-7GS

PAGE 112

113 aggregate have significant lower splitting tensile strength. For example, Mix-3F has an average splitting tensile strength of 731 psi at 91 days, while the splitting tensile strength of the corresponding Mix-3GF is 624 psi. At 91 days, the sp litting tensile strength of Mix-5S is 738 psi, which is 16.8% higher than that of the corresponding Mix-5GS. 5.3.3 Effects of Fly Ash and Slag on Spli tting Tensile Strength of Concrete Fly ash and slag have significant effect on sp litting tensile strength. In order to see the effects of fly ash and slag on splitting tensile strength, the strength development characteristics of splitting tensile strength was normalized as th e ratio of splitting tensile strength at various curing ages to the splitting tensile strength at 91 days and the normalized values are listed in Table A-4 in Appendix A. As can be seen from Ta ble A-4, the splitting tensile strengths of fly ash concrete mixtures increase sl owly in 28 days after demolding, and the 28-day splitting tensile strength is around 85% of splitting tensile strength at 91 days, wh ile the splitting tensile strength of slag concrete increased very rapidly in 28 da ys after demolding, up to 94% of splitting tensile strength at 91 days. For example, the splitting tensile strength of Mix-2F at 91 days is 659 psi, increasing 21.6 percent in comparison with that at 28 days. Mix-3F has a splitting tensile strength of 731psi at 91 days, increasing 17.1 percent in co mparison with that at 28 days. Bu t, for the concrete mixtures with slag and limestone coarse aggregate, there is no appreciable increase in splitting tensile strength after 28 days curing. For example, Mix-5S, Mix-6S, Mix-7S, and Mix-8S increase in splitting tensile strength by less than 10% at 91 days as compared with that at 28 days. For the concrete mixtures with Georgia granite aggregate, substantial increase in splitting tensile strength after 28 days also happened to the mixtures with fly ash, while no signi ficant increase was found in concrete mixtures with slag. For two lightweight aggregate conc rete mixtures, similar situation can be observed as well.

PAGE 113

114 The development characteristics of two typical fly ash concretes and two slag concretes with time are shown in Figure 5-16. 0.70 0.75 0.80 0.85 0.90 0.95 1.00 02 04 06 08 01 0 0 Time (days)Ratio to Splitting tensile Strength at 91 days Mix-5S-Slag-W/C=0.33 Mix-6S-Slag-W/C=0.36 Mix-2F-Fly ash-W/C=0.33 Mix-4F-Fly ash-W/C=0.37 Figure 5-16 Effects of fly ash and slag on splitting tensile strength of concrete 5.4 Relationship between Compressive St rength and Splitting Tensile Strength The compressive strengths of the concretes (as tabulated in Table A-1) were plotted against the corresponding splitting tensile strengths (as ta bulated in Table A-2) for all curing conditions in Figure 5-17. Regression analyses to establ ish empirical relationship between compressive strength and splitting tensile strengths were performed using the following equations: 'c fA ct f (5-3) Bc f ct f (5-4) where ctf= splitting tensile strength (psi) 'cf= compressive strength (psi)

PAGE 114

115BA,= coefficients The ACI Code 318 uses Equation 5-3 for estimation of splitting tensile strength of lightweight concrete, where the coefficient A is equal to 6.7 [ACI, 1983]. The investigation by Carino and Lew [Carino et al, 1982] determined that the coeffici ent A was approximately 6.49. They suggested that Equation 5-4 was better than Equation 5-3 in the estimation of splitting tensile strength from compressive strength. The coefficient B was determined to be 0.73 in their investigation. The results of the regression analyses are su mmarized in Table 5-4. The coefficient A (6.91) is slightly higher than both the values suggested by ACI (6.7) and the value by Carino and Lew (6.49). The coefficient B (0.7185) is slig htly lower than that s uggested by Carino and Lew (0.73). These two regression equations are also plotted on Figure 5-17. As can be seen from Figure 5-17, Carino and Lew model gives a better fit to the experimental data than the ACI model, while ACI Building Code 318-92 tends to overestimate splitting tens ile strength at low compressive strength and underestimate splitting tensile strength at high compressive strength because the power exponent of the equation is too low. Table 5-6 Regression analysis for relating compre ssive strength to spli tting tensile strength Equation Curing condition Coefficient A or B Standard Error Square root of absolute sum of squares by modified equation Square root of absolute sum of squares by original equation 7.6' A fAf ACIc st Moist curing 6.91 0.76 60 62.3 73.0' B ff Lewand CarinoB cst Moist curing 0.72 0.015 45 75.7

PAGE 115

116 0 100 200 300 400 500 600 700 800 900 1000 02000400060008000100001200014000 Compressive Strength (psi)Splitting Tensile Strength (psi) Measurement Carino and Lew model ACI code Figure 5-17 Relationship between compressive strength and splitting tensile strength

PAGE 116

1175.5 Analysis of Elastic Modulus Test Results The average elastic modulus values at various curing ages of the four teen concrete mixes evaluated are displayed in Table 5-7. The indivi dual elastic modulus values are shown in Table A-3 in Appendix A. Table 5-7 Elastic module of the concrete mixtures evaluated ( 106 psi) Age of Testing (days) Mix Number W/C Fly ash Slag 3 7 14 28 56 91 Mix-1F 0.24 20% 4.74 4.93 5.23 5.40 5.54 5.58 Mix-2F 0.33 20% 3.43 3.77 4.08 4.31 4.43 4.67 Mix-3F 0.41 20% 4.40 4.85 5.05 5.14 5.28 5.70 Mix-4F 0.37 20% 4.49 4.61 4.88 5.01 5.15 5.29 Mix-5S 0.33 50% 4.11 4.66 4.88 5.09 5.23 5.23 Mix-6S 0.36 50% 4.27 4.92 5.18 5.45 5.62 5.66 Mix-7S 0.41 70% 3.90 4.30 4.52 4.60 4.73 4.76 Mix-8S 0.44 50% 3.96 4.39 4.84 5.00 5.13 5.16 Mix-9LF 0.31 20% 2.76 2.92 3.13 3.27 3.40 3.50 Mix-10LS 0.39 60% 1.75 1.88 2.36 2.69 3.01 3.04 Mix-2GF 0.33 20% 3.80 4.22 4.61 4.96 5.06 5.19 Mix-3GF 0.41 20% 4.15 4.62 5.52 5.61 5.93 5.96 Mix-5GS 0.33 50% 3.15 3.82 4.65 5.17 5.37 5.56 Mix-7GS 0.41 70% 2.69 3.38 4.10 5.25 5.60 5.73 As can be seen from Table 5-7, for the norma l weight aggregate conc retes investigated in this study, the elastic modulus of concrete varies from 4.50 106 to 6.00 106 psi. For the lightweight aggregate conc rete, the modulus of elas ticity varies from 3.00 106psi to 3.70 106 psi. As shown in Figures 5-18 through 5-21, two di fferent normal weight coarse aggregates give considerable influence on the elastic modul us of concrete. With other mixture components constant in volume, the concrete mixtures with Georgia granite aggreg ate have higher elastic modulus than those with Miami Oolite limestone aggregate. For example, Mix-7GS has an elastic modulus of 5.73 106 psi at 91 days, 20.4% higher than 4.76 106 psi, which is the value of elastic modulus of Mix-7S at 91 days. Mix-7S has a compressive strength at 91 days slightly higher than that of Mix-7GS. Also, we can s ee from the comparison between Mix-2F and Mix-

PAGE 117

118 2GF, Mix-3F and Mix-3GF, and Mix-5S and Mix5GS that Mix-2F, Mix-3F and Mix-5S have a lower elastic modulus than th e corresponding Mix-2GF, Mix-3GF and Mix-5GS, respectively. The compressive strengths of Mix-2F, Mix-3F and Mix-5S are higher than those of the corresponding Mix-2GF, Mix-3GF and Mix-5GS, respectively, at various curing ages. It is interesting to note that high strength but low elastic m odulus concrete can be obtained through using lightweight aggregat e. For example, Mix-9LF, light weight aggregate concrete, has similar compressive strength and splitting tens ile strength to Mix-7S, with Miami Oolite limestone aggregate, while the elastic modulus of Mix-9LF at 91 days is only about 3.50 106 psi, which is about 36% lower than that of Mix-7S Thus, to achieve high strength but low elastic modulus concrete mixture, which is desirable for concrete pavement, a lightweight aggregate may be used. 0.00E+00 1.00E+06 2.00E+06 3.00E+06 4.00E+06 5.00E+06 6.00E+06Modulus of Elasticity (psi) Curing Age (days) Limestone 03.43E+063.77E+064.08E+064.31E+064.43E+064.67E+06 Granite 03.80E+064.22E+064.61E+064.96E+065.06E+065.19E+06 0371 42 85 69 1 Figure 5-18 Effects of coarse ag gregate type on modulus of elas ticity of Mix-2F and Mix-2GF

PAGE 118

119 0.00E+00 1.00E+06 2.00E+06 3.00E+06 4.00E+06 5.00E+06 6.00E+06Modulus of Elasticity (psi) Curing Age (days) Limestone 04.40E+064.85E+065.05E+065.14E+065.28E+065.70E+06 Granite 04.15E+064.62E+065.52E+065.61E+065.93E+065.96E+06 0371 42 85 69 1 Figure 5-19 Effects of coarse ag gregate type on modulus of elas ticity of Mix-3F and Mix-3GF 0.00E+00 1.00E+06 2.00E+06 3.00E+06 4.00E+06 5.00E+06 6.00E+06Modulus of Elasticity (psi) Curing Age (days) Limestone 04.11E+064.66E+064.88E+065.09E+065.23E+065.23E+06 Granite 03.15E+063.82E+064.65E+065.17E+065.37E+065.56E+06 0371 42 85 69 1 Figure 5-20 Effects of coarse ag gregate type on modulus of elas ticity of Mix-5S and Mix-5GS

PAGE 119

120 0.00E+00 1.00E+06 2.00E+06 3.00E+06 4.00E+06 5.00E+06 6.00E+06Modulus of Elasticity (psi) Curing Age (days) Limestone 03.90E+064.30E+064.52E+064.60E+064.73E+064.76E+06 Granite 02.69E+063.38E+064.10E+065.25E+065.60E+065.73E+06 0371 42 85 69 1 Figure 5-21 Effects of coarse ag gregate type on modulus of elas ticity of Mix-7S and Mix-7GS 5.6 Relationship between Compressive Strength and Elastic Modulus The elastic modulus of concrete is affected by the modulus of elasticity of the aggregate and by the volumetric proportion of aggregate in the concrete. Thus, there is no surprise that there is no agreement on the precise form of th e relationship between compressive strength and elastic modulus. In this study, modification was made on the expression recommended by ACI 318-89, given as follows: c cfE (5-5) In the equation is a parameter to be determined thr ough curve-fitting regression analysis. Its value recommended by ACI is 57000.

PAGE 120

121 The regression analysis was carried out on the expression recommended by ACI 318-95, given as follows, to fit the expe rimental data. In this formula, the unit weight of concrete was also used. '5.1 cfwAE (5-6) Where E is elastic modulus in psi; 'cf is compressive strength in psi; wis unit weight of concrete in pcf; and A is coefficient to be determined through regression analysis. The recommended value by ACI 318-95 is 33.0. The compressive strengths of fourteen concre te mixtures were pl otted against elastic modules at corresponding curing ages, as shown in Figure 5-22. It indicates that coarse aggregate type has significant effects on the elastic modulus of concrete. The results from regression analysis were presented in Table 5-8. And th e modified ACI 209 equati on was plotted in Figure 5-22 together with the ex perimental measurements. It can be seen that the determined values of coefficient for the concrete mixtures with three different types of aggregate are fairly fa r away from the ACI suggested value of 57000. Regression analysis was performed using ACI 318-95 equation, which was required to go through the origin. The analyzed re sults are presented in Table 5-9. It can be seen from Table 59 that the coefficient A (33.64) obtained from re gression analysis is ne arly identical to the coefficient (33.0) given by ACI code. However, th e errors from the regr ession equation which is required to go though the origin are higher than th ose from that regression equation that is not required to go through the origin, as seen from Table 5-9. In addition, the results of regression analysis for differe nt curing conditions using ACI 318-95 formulas are presented in Table 5-10. Th e elastic modulus of concrete at all curing conditions is plotted against '5.1 cfw in Figure 5-23. As can be seen from Table 5-10, curing

PAGE 121

122 time appears to have a significant effect on the coefficient of the regression equations. The regression coefficients obtained from the sample s moist-cured for 28 days are higher than those obtained from other curing times. Thus, the pred iction will be conserva tive if the regression coefficients are obtained from the samples moist-cured for 28 days. For the concretes investigated in this st udy, the following modified ACI 318-95 equation can be used for prediction of elastic modulus: 484200 '5.1 16.30 c fw E (5-7) Where E is elastic modulus in psi; 'cf is compressive strength in psi; wis unit weight of concrete in pcf. 5.7 Summary of Findings This chapter presents the testing results from the strength tests in this study. The major findings are given as follows: (1) Splitting tensile strengths of the concrete mixtures using granite aggregate were significantly lower than thos e using Miami Oolite limestone aggregate. This is due probably to the poor bonding condition betw een hardened cement paste and granite aggregate. (2) Compressive strengths of concretes with gran ite aggregate were comparable to or lower than those of concretes with Miami Oolite limestone aggregate. (3) The concrete with granite aggregate had hi gher elastic modulus than that with Miami Oolite limestone aggregate, while the lightweight aggregate concretes had lower elastic modulus than the normal weight concretes. (4) Fly ash concretes develop compressive strength and splitting tensile st rength at a slower rate than the slag concretes. Fly ash conc rete shows significant strength gain after 28 days, while this was not seen fr om the slag concrete mixtures. (5) The ACI 209 Equation for prediction on compressive strength () ('tfc) at various curing age from compressive strength at 28 days () (' 28tfc), which is given as follows, was modified to give better strength prediction for the various mixtures.

PAGE 122

123 Table 5-8 Results of regression analysis for prediction of elastic modulus using the equation recommended by ACI 318-89 Aggregate type Results granite lightweight Limestone (Best-fit values) 62721 43777 55949 Standard Error of 870.6 692.3 309.1 95% confidence intervals for 60920 to 64523 42253 to 45301 55327 to 56572 Degrees of Freedom 23 11 47 R 0.8712 0.922 0.8758 Absolute Sum of Squares 2.478E+12 2.693E+11 1.619E+12 Sy.x 328220 156461 185594 Number of points Analyzed 24 12 48 Table 5-9 Results of regression analysis for prediction of elastic modulus using ACI 318-95 equation Best-fit values With equation going through the origin Without forcing the equation to go through the origin Slope 33.64 0.2671 30.18 1.169 Y-intercept when X=0.0 0.0000 484200 159900 X-intercept when Y=0.0 0.0000 -16040 1/slope 0.02973 0.03313 95% Confidence Intervals Slope 33.10 to 34.17 27.85 to 32.51 Sy.x 335100 319700

PAGE 123

124 0.00E+00 1.00E+06 2.00E+06 3.00E+06 4.00E+06 5.00E+06 6.00E+06 7.00E+06 8.00E+06 02000400060008000100001200014000 Compressive Strength (psi)Modulus of Elasticity (psi) Georgia granite Stalite lightweight Miami Oolite limestone Figure 5-22 Relationship between compressive strength and elasti c modulus based on ACI Code 0.00E+00 1.00E+06 2.00E+06 3.00E+06 4.00E+06 5.00E+06 6.00E+06 7.00E+06 04000080000120000160000200000 w1.5fc 0.5Modulus of Elasticity Figure 5-23 Plot of elastic modulus against '5.1 cfw for all curing conditions

PAGE 124

125Table 5-10 Results of regression analysis for prediction of elastic modulus using the ACI 318-95 equation for different curing conditions Age Results overall 3-day 7-day 14-day 28-day 56-day 91-day Slope 30.18 1.169 26.24 3.857 27.76 3.763 29.17 3.123 30.00 2.217 28.78 2.965 29.38 2.771 Y-intercept when X=0.0 484200 159900 800000 437100 644500 478400 614000 424400 581900 315800 779700 438000 704200 418700 X-intercept when Y=0.0 -16040 -30490 -23220 -21050 -19400 -27090 -23970 1/slope 0.03313 0.03811 0.03602 0.03428 0.03334 0.03475 0.03404 95% Confidence Intervals Slope 27.85 to 32.51 17.84 to 34.64 19.56 to 35.96 22.37 to 35.98 25.16 to 34.83 22.32 to 35.24 23.34 to 35.41 Y-intercept when X=0.0 165500 to 802900 -152400 to 1752000 -397900 to 1687000 -310800 to 1539000 -106200 to 1270000 -174800 to 1734000 -208100 to 1616000 X-intercept when Y=0.0 -28780 to 5098 -97520 to 4433 -85720 to 11130 -68530 to 8673 -50350 to 3056 -77450 to 4974 -69070 to 5892 Goodness of Fit r 0.8906 0.7941 0.8194 0.8791 0.9385 0.887 0.9035 Sy.x 319700 394800 386700 310500 216700 292900 275100 Is slope significantly non-zero? F 667.2 46.29 54.43 87.25 183.1 94.22 112.4 DFn, DFd 1.000, 82.00 1.000, 12.00 1.000, 12.00 1.000, 12.00 1.000, 12.00 1.000, 12.00 1.000, 12.00 P value < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 Deviation from zero? Significant Significant Significant Significant Significant Significant Significant Data Number of X values 84 14 14 14 14 14 14 Maximum number of Y replicates 1 1 1 1 1 1 1 Total number of values 84 14 14 14 14 14 14

PAGE 125

126 28 85.00.4 )( c f t t t c f The modified equation has the following form for the concrete with different coarse aggregates: 28 )( c f t t t c f The value of was found to vary from 1.1 to 2.6 for the concretes with Miami Oolite limestone aggregate, from 2.6 to 5.3 for th e concretes with Georgia granite aggregate, and from 4.2 to 6.7 for lightweight aggregate concretes; the value of was found to vary from 0.82 to 0.93 for the concretes with Miam i Oolite limestone aggregate, from 0.82 to 0.89 for the concrete with Georgia granite aggregate, and from 0.74 to 0.82 for lightweight aggregate co ncrete in this study. (6) The relationship between compressive strength ('cf ) and splitting tensile strength (ctf ) is established for the concrete mixtures investigated in this study. The Carino and Lew model, given as follows, 73.0 c f ct f was modified to the following equation: 7185.0 c f ct f Where cf and ctf are in units of psi. (7) The relationship between compressive strength and modulus of elasticity was refined in this study using Least Square of Curvefitting Technique. The ACI 318-89 Equation, which is '57000cf c E was modified to the following equation: cf c E Where is equal to 55,949 for Miami Oolite lim estone aggregate; 62,721 for Georgia granite aggregate; and 43,777 for Stalite lightweight aggregate. cf and cE are in units of psi. (8) For all three aggregate type s investigated in this study, a modified ACI 318-95 prediction equation was developed: 484200 16.30'5.1cfw E Where w is the density of c oncrete in pound per cubit foot. 'cf and cE are in units of psi.

PAGE 126

127 CHAPTER 6 ANALYSIS OF SHRINKAGE TEST RESULTS 6.1 Introduction This chapter presents the results from shrinka ge tests on the concrete mixes evaluated in this study. The effects of various factors on shrinkage behavior of concrete were discussed. Regression analysis was performed to establish the relationship between compressive strength at the age when shrinkage test was started and sh rinkage strain at 91 days, and the relationship between elastic modulus and shrinkage of conc rete. Empirical equations relating compressive strength and elastic modulus to shrinkage of c oncrete are given. Also, the evaluation was made on ACI 209 model and C.E.B-F.I.P model for their e ffectiveness in shrinkage prediction. At last, ultimate shrinkage strain of the concretes invest igated in this study was approximated using an asymptotic equation with three unknown pa rameters to fit experimental data. 6.2 Results and Analysis of Shrinkage Tests Table 6-1 presents the measured shrinkage strain s at the ages up to 91 days for the fourteen concrete mixes evaluated in this study. Fo r Mix-1F through Mix-10LS, one group of concrete specimens was moist-cured for 7 days and then air-dried in the laboratory for the rest of the time; another group of specimens were moist-cured for 14 days and then air-dried for the rest of the time, while, for Mix-2FG through Mix-7SG, only one curing condition, i.e. 14-day moist curing and then air-dried for the rest of time, was evaluated. 6.2.1 Effects of Curing Conditions on Shrinkage Behavior of Concrete As can be seen from Table 6-1 as well as Figure 6-1, curing co ndition has substantial effects on shrinkage behavior of concrete mixtures For the concrete mixtures with fly ash, the specimens moist-cured for 14 days have apprecia ble lower shrinkage strains than those moist cured for 7 days. For example, the shrinkage strain of Mix-1F moist-cured for 14 days is

PAGE 127

128 Table 6-1 Shrinkage strains of the concrete mixtures evaluated at various curing ages Age of testing (days) No. of Mix Curing condition 3 7 14 28 56 91 Predicted ultimate shrinkage strain 7-day moist cure 0.20E-04 0.44E-04 0.75E-04 1.18E-04 1.63E-04 2.02E-04 2.66E-04 Mix-1F 14-day moist cure 0.14E-04 0.35E-04 0.61E-04 1.00E-04 1.36E-04 1.67E-04 2.27E-04 7-day moist cure 0.51E-04 0.97E-04 1.54E-04 2.10E-04 2.61E-04 2.86E-04 3.39E-04 Mix-2F 14-day moist cure 0.31E-04 0.69E-04 1.12E-04 1.73E-04 2.33E-04 2.58E-04 3.20E-04 7-day moist cure 0.40E-04 0.73E-04 1.24E-04 1.77E-04 2.21E-04 2.48E-04 3.03E-04 Mix-3F 14-day moist cure 0.24E-04 0.50E-04 0.87E-04 1.37E-04 1.84E-04 2.16E-04 2.85E-04 7-day moist cure 0.37E-04 0.71E-04 1.18E-04 1.76E-04 2.33E-04 2.67E-04 3.64E-04 Mix-4F 14-day moist cure 0.31E-04 0.53E-04 0.92E-04 1.42E-04 1.97E-04 2.31E-04 3.44E-04 7-day moist cure 0.44E-04 0.88E-04 1.30E-04 1.70E-04 2.01E-04 2.16E-04 2.46E-04 Mix-5S 14-day moist cure 0.43E-04 0.74E-04 1.10E-04 1.49E-04 1.78E-04 1.93E-04 2.29E-04 7-day moist cure 0.42E-04 0.84E-04 1.23E-04 1.56E-04 1.83E-04 1.95E-04 2.16E-04 Mix-6S 14-day moist cure 0.33E-04 0.71E-04 1.12E-04 1.41E-04 1.64E-04 1.76E-04 1.93E-04 7-day moist cure 0.39E-04 0.81E-04 1.26E-04 1.70E-04 2.02E-04 2.23E-04 2.55E-04 Mix-7S 14-day moist cure 0.38E-04 0.73E-04 1.11E-04 1.48E-04 1.84E-04 2.04E-04 2.40E-04 7-day moist cure 0.73E-04 1.23E-04 1.61E-04 1.94E-04 2.28E-04 2.50E-04 2.43E-04 Mix-8S 14-day moist cure 0.50E-04 0.98E-04 1.36E-04 1.69E-04 2.02E-04 2.30E-04 2.20E-04 7-day moist cure 0.49E-04 0.96E-04 1.34E-04 2.25E-04 2.87E-04 3.22E-04 3.95E-04 Mix-9LF 14-day moist cure 0.46E-04 0.83E-04 1.34E-04 1.84E-04 2.41E-04 2.76E-04 3.49E-04 7-day moist cure 0.67E-04 1.30E-04 1.98E-04 2.60E-04 3.20E-04 3.58E-04 4.22E-04 Mix-10LS 14-day moist cure 0.38E-04 0.90E-04 1.52E-04 2.09E-04 2.80E-04 3.17E-04 3.96E-04 7-day moist cure --------------Mix-2GF 14-day moist cure 0.32E-04 0.61E-04 1.09E-04 1.61E-04 2.04E-04 2.31E-04 2.83E-04 7-day moist cure --------------Mix-3GF 14-day moist cure 0.29E-04 0.54E-04 0.84E-04 1.23E-04 1.57E-04 1.82E-04 2.62E-04 7-day moist cure --------------Mix-5GF 14-day moist cure 0.39E-04 0.64E-04 1.04E-04 1.40E-04 1.68E-04 1.84E-04 2.18E-04 7-day moist cure --------------Mix-7GF 14-day moist cure 0.43E-04 0.74E-04 1.00E-04 1.31E-04 1.63E-04 1.81E-04 2.19E-04

PAGE 128

129 0.000167 at 91 days, which is 23.2% less than that of the same mix moist-cured for 7 days. The shrinkage strain at 91 days is 0.000258 for Mix2F moist-cured for 14 days, which is 10.9% less than that of the same mix moist-cured for 7 da ys. Also, the shrinkage strain of Mix-3F moistcured for 14 days is 0.000216, which is 14.8% less than that of the same mix moist-cured for 7 days. Substantial decrease in shrinka ge strain also can be seen from Mix-4F. Shrinkage strain of 7-day moist-cured specimens is 13.5% higher th an that of 14-day moist-cured specimens for Mix-4F. For the concrete mixtures with slag, the eff ects of curing condition on shrinkage strain are significant as well. For instance, the shrinkage stra in of Mix-5S moist-cure d for 14 days is 11.9% less than that of the same mix moist-cured for 7 days. Also, for Mix-6S, Mix-7S and Mix-8S, the shrinkage strains of the specimens moist-cured for 14 days are at least 10% less than those of the same mixtures moist-cured for 7 days. In addition, curing condition has similar e ffects on shrinkage st rain of lightweight aggregate concretes as that on normal weight aggregate concrete. The shrinkage strains of Mix9FL and Mix-10SL moist-cured for 14 days are 16. 5% and 11.6%, respectively, less than those of the same mixtures moist-cured for 7 days. 6.2.2 Effects of Mineral Additi ves on Shrinkage Behavior As can be seen from Table 6-1 as well as Fi gure 6-1, the results from 14 mixtures indicate that the concrete mixtures with fly ash have hi gher shrinkage strains than those with slag. For example, Mix-3F has the same water to ceme ntitious materials ratio as Mix-7S, while the shrinkage strain of Mix-3F mois t-cured for 7 days is 0.000248, which is more than 10% higher than that of Mix-7S moist-cured for 7 days ev en though the water content of Mix-3F (254 lbs per cubit yard) is less than that of Mix-7S (267 lbs per cubit yard). For another example, Mix-2F and

PAGE 129

130 0.00E+00 5.00E-05 1.00E-04 1.50E-04 2.00E-04 2.50E-04 3.00E-04 3.50E-04 4.00E-04 1F2F3F4F5S6S7S8S9LF10LS MixtureShrinkage Strain at 91 days 7day moist curing 14-day moist curing Figure 6-1 Effects of curing condition on shrinkage strain of concrete mixtures at 91 days Mix-5S have identical water to cementitious ratio, while the shrinkage strain of Mix-2F moistcured for 7 days is 0.000286 at 91 days, or 24.5% higher than that of Mix-5S moist-cured for 7 days. As also can be seen from the concrete mixt ures with Georgia granite aggregate, Mix-2FG and Mix-3FG have higher shrinkage strains as compared with the corresponding Mix-5SG and Mix-7SG, respectively, even though Mix-2GF has identical water to cementitious materials ratio as Mix-5SG, and Mix-3GF has the same water to cementitious material ratio as Mix-7GS. 6.2.3 Effects of Water Content on Shrinkage Behavior Water content per unit volumetric concrete is an important fact or influencing the magnitude of shrinkage strain since drying shrink age is caused by the moisture movement from the concrete. Generally, the higher the water conten t, the more the free water inside concrete is available because water can not be consumed rapi dly and completely. Thus, shrinkage strain of concrete is increased with an increase of free wate r content. As can be seen from Figure 6-2, the

PAGE 130

131 shrinkage strains at 91 days increase with the increase of water content for the normal-weight concrete mixtures eval uated in this study. 0.00E+00 5.00E-05 1.00E-04 1.50E-04 2.00E-04 2.50E-04 3.00E-04 3.50E-04 220230240250260270280290 Water Content (lbs/yard3)Shrinkage Strain at 91 days Miami Oolite limestone Georgia granite Figure 6-2 Effects of water content on shrinkage strain at 91 days Figure 6-3 shows a plot of water to cementitious materials ratio versus shrinkage strain of concrete at 91 days. No clear tr end can be observed to relate wate r to cementitious materials ratio to the magnitude of shrinkage strain of concrete. The significant role played by water content also extends to the lightweight aggregate concretes, Mix-9FL and Mix-10SL. As can be s een from Table 6-1, the water content of Mix10SL is 275 lbs per cubit yard, higher than 235 lbs fo r Mix-9FL. The shrinkage strain at 91 days for Mix-10SL is much higher than that of Mix-9FL. 6.2.4 Effects of Aggregate Types on Shrinkage Behavior In this study, two types of normal weight coarse aggregate, Miami Oolite limestone aggregate and Georgia granite aggregate were investigated for their effects on shrinkage

PAGE 131

132 behavior of four concrete mixtures. The experi mental data from the specimens moist-cured for 14 days indicate that the concrete mixtures using Georgia granit e aggregate developed significantly less shrinkage strain at 91 days than those with Mi ami Oolite limestone aggregate. For example, as can be seen from Figure 6-4, Mix-2FG, which has the same mix proportion as Mix-2F other than the coarse aggregate replaced by Georgia granite aggregate, has a shrinkage strain of 0.000231, which is 23.8% lower than th at of Mix-2F using Miami Oolite limestone as coarse aggregate. 0.24 0.33 0.41 0.37 0.33 0.36 0.41 0.44 0.33 0.41 0.33 0.41 0.24 0.33 0.33 0.41 0.36 0.41 0.44 0.37 1.00E-04 1.20E-04 1.40E-04 1.60E-04 1.80E-04 2.00E-04 2.20E-04 2.40E-04 2.60E-04 2.80E-04 0.200.250.300.350.400.450.50 Water to Cementitious Materials RatioShrinkage Strain at 91 days Miami Oolite limestone Georgia Granite Figure 6-3 Plot of water to cementitious material s ratio versus shrinkage strain at 91 days The same situation can be seen from the comparison between Mix-3F and Mix-3FG, Mix5S and Mix-5SG, and Mix-7S and Mix-7SG. The shrinkage strain of Mix-3FG is 0.000182 at 91 days, which is 18.7% less than that of Mi x-3F, which has shrinkage strain of 0.000216. Shrinkage strains of Mix-5S and Mix-7S at 91 da ys are also 10% higher than those of Mix-5SG and Mix-7SG.

PAGE 132

133 For lightweight aggregate conc retes, such as Mix-9LF a nd Mix-10LS, their shrinkage strains are significantly higher th an the concrete mixtures using normal weight aggregate. 0.00E+00 5.00E-05 1.00E-04 1.50E-04 2.00E-04 2.50E-04 3.00E-04 Mix-2 Mix-3 Mix-5 Mix-7 MixtureShrinkage Strain at 91 days Miami Oolite limestone Georgia granite Figure 6-4 Effects of coarse aggregate t ype on shrinkage behavior of concrete 6.2.5 Relationship between Compressive Strength and Shrinkage Strain Over the past decades, the study on shrinkage be havior of concrete has been carried out extensively. The effects of various factors, su ch as water to cement ratio, aggregate type, aggregate content, mineral additives, and cement content so on, on shrinkage behavior have been studied. However, since concrete is a complicat ed composite material, the effects of various components and their proportions on shrinkage beha vior are intertwisted together. Also, because of massive introduction of chemi cal admixtures to concrete, su ch as air entraining agent and water reducer, shrinkage behavior of concrete becomes more complex. Thus, shrinkage behavior of concrete can not be reasona bly estimated based on the simple addition of every individual factors function. Therefore, it is desirable to relate the shrinkage behavior of conc rete to one or more fundamental properties of concrete, for exam ple, compressive strength, tensile strength or elastic modulus at a particular age. In doing so, it assumes that the fundamental properties of

PAGE 133

134 concrete are closely related to one another, i.e. one fundamental property can be predicted from another. In doing so, a complicated fundame ntal property can be estimated by a simple fundamental property without complicated and time-consuming experimental test involved. In trying to find out the relationship between compressive strength and shrinkage behavior of concrete, compressive strength at the age when shrinkage test was star ted was plotted against shrinkage strain at 91 days in Figure 6-5. As shown in Figure 6-5, it appe ars that there exists a very interesting relationship between the shrinkage strains at 91 days and compressive strength regardless of which type of coarse aggregate was used for concrete. Then, regression analysis was carried out using an exponential function with two unknown parameters, given as E quation 6-1. The regression analysis results are presented in Table 6-2. cf she (6-1) In this formula, fc is compressive strength of concrete at the age of initial shrinkage test. As can be seen from Table 6-2, best fit value of is 5.11310-4; best fit value of is 1.12710-4; and correlation coefficient, R2, is 0.8226. The above equation with parameters obtained from regression analysis was plotted in Figure 6-5 as solid line. It indicated that shrinkage strain at 91 days can be well estimate d by the compressive strength of concrete at the age of when shrinkage test was started. Furtherm ore, this relationship is not affected by such factors as aggregate t ype and curing age. Therefore, even though exponential equation from regression analysis may not be a fundamental relationship between compressive st rength and shrinkage of concrete, it may be very convenient way practically to have an accu rate enough estimation on shrinkage strain just based on the compressive strength without time-consuming shrinkage test involved.

PAGE 134

135 Table 6-2 Results of regression analysis on rela tionship of compressive strength to shrinkage strain Regression Results Best-fit Value Standard Error (SE) 95% Confidence Interval R2 Absolute Sum of Square Root due to Error (SSE) 5.113E-04 2.042E-05 4.706E-04~ 5.521E-04 1.127E-04 5.654E-06 1.014E-04~ 1.239E-04 0.8226 2.131E-05 0.00E+00 5.00E-05 1.00E-04 1.50E-04 2.00E-04 2.50E-04 3.00E-04 3.50E-04 4.00E-04 4.50E-04 5.00E-04 02000400060008000100001200014000 Compressive Strength at the Age of Initial Shrinkage Test (psi)Shrinkage Strain at 91 Days Miami Oolite limestone Lightweight aggregate Georgia granite Figure 6-5 Relationship between compressive strength and shrinkage strain at 91 days 6.2.6 Relationship between Elastic Modulus and Shrinkage Strain Since close relationship has been found between compressive strength and shrinkage of concrete, and since there is direct relations hip between compressive strength and elastic modulus, elastic modulus and shrinkage shoul d be related to each other as well. As shown in Figure 6-6, shrinka ge strains at 91 days for all the concretes investigated in this study, including normal weight aggregate concrete and lightweight aggregate concrete, were plotted against elastic modulus at the age of shrinkage test starts. There is no surprise that similar

PAGE 135

136 relationship to compressive strength and shrinkage can be f ound between elastic modulus and shrinkage. Regression analysis was performed using an exponential function with two unknown parameters, as given in Equation 6-2, and the analyzed results are presented in Table 6-3. cE she (6-2) In this equation, Ec is elastic modulus of concrete at the age when shrinkage test was started. Table 6-3 Results of regression analysis on relati onship of elastic modulus to shrinkage strain Regression Results Best-fit Value Standard Error (SE) 95% Confidence Interval R2 (SSE) 6.595E-04 3.429E-05 5.911E-04~ 7.279E-04 2.270E-07 1.129E-08 2.045E-04~ 2.495E-04 0.8152 2.175E-05 0.00E+00 1.00E-04 2.00E-04 3.00E-04 4.00E-04 5.00E-04 0.00E+002.00E+064.00E+066.00E+068.00E+06 Modulus of Elasticity (psi)Shrinkage Strain at 91 Days Miami Oolite limestone Lightweight aggregate Georgia granite Figure 6-6 Relationship between shrinkage stra in at 91 days and modulus of elasticity

PAGE 136

1376.3 Evaluation on Shrinkage Prediction Models In this study, the ACI 209 model and C.E. B-F.I.P model were evaluated on their effectiveness and accuracy in prediction of shri nkage behavior of typical concretes used in Florida. 6.3.1 ACI-209 model The concrete shrinkage prediction model recommended by ACI-209 (1992) is given as follows: u sh t t t sh 35 (6-3) Where t sh time dependent shrinkage strain; u sh ultimate shrinkage strain; and t time variable in days If there is no available shrinkage data from the specific concrete mixture, the ultimate shrinkage strain,u sh can be assumed to be the following: sh u sh 610780 (6-4) Where sh a product of all the applic able correction factors for the testing conditions other than the standard condition; sh = 1 under standard testing condition. sh is obtained by multiplying the ultimate shri nkage strain under the standard condition by the appropriate correction factors, such as correction factors for the effect of initial moist curing, correction factor for the effect of ambient relative humidity, corre ction factor for the effects of specimen size, correction factor for concre te composition and so on. In this study, sh is calculated as follows: patasrhlash (6-5) The correction factors a pplicable to the concrete mixes ev aluated in this study are shown in Table 6-4.

PAGE 137

138 Table 6-4 Correction factors for the ACI 209 model on shrinkage prediction la sh No. of Mix 7-day moist 14-day moist rh s a at p 7-day moist 14-day moist Mix-1F 0.916 0.814 0.77 0.85 0.57 1.00 0.88 0.30 0.27 Mix-2F 0.916 0.814 0.77 0.83 0.87 1.00 0.88 0.45 0.40 Mix-3F 0.916 0.814 0.77 0.83 0.69 1.00 0.88 0.36 0.32 Mix-4F 0.916 0.814 0.77 0.83 0.64 1.00 0.88 0.33 0.29 Mix-5S 0.916 0.814 0.77 0.84 0.80 1.00 0.88 0.42 0.37 Mix-6S 0.916 0.814 0.77 0.83 0.66 1.00 0.88 0.34 0.30 Mix-7S 0.916 0.814 0.77 0.84 0.96 1.00 0.88 0.50 0.44 Mix-8S 0.916 0.814 0.77 0.83 0.80 1.00 0.88 0.41 0.37 Mix-9LF 0.916 0.814 0.77 0.83 0.73 1.00 0.88 0.38 0.33 Mix-10LS 0.916 0.814 0.77 0.83 0.93 1.00 0.88 0.48 0.43 Mix-2GF 0.916 0.814 0.77 0.83 1.13 1.00 0.88 0.58 0.52 Mix-3GF 0.916 0.814 0.77 0.83 0.60 1.00 0.88 0.31 0.27 Mix-5GS 0.916 0.814 0.77 0.84 0.96 1.00 0.88 0.50 0.44 Mix-7GS 0.916 0.814 0.77 0.83 0.80 1.00 0.88 0.41 0.37 6.3.2 CEB-FIP Model In this model, the effects of cement type, ambient relative humidity, compressive strength of concrete, and size effect of specimen on sh rinkage strain of concrete are taken into consideration. The total shri nkage strain may be estimate d by the following equation: s tt scss tt cs 0 (6-6) Where scstt = time dependent total shrinkage strain; 0 cs = notational shrinkage coefficient; and s (t ts) = coefficient to describe the development of shrinkage with time. 0 cs can be estimated by the following equation: RH cmo cm sc csf f 6 010 910 160 (6-7) wheresc a coefficient depending on the type of cem ent is equal to 5 for normal or rapid hardening cements; cmf = the mean compressive strength of concrete at the age of initial shrinkage tests. cmof is a constant, equal to 10MPa. RH can be computed as follows:

PAGE 138

139 3 0 155.1 RH RH RH for %99 %40 RH (6-8) With RH equal to 75% in this study and 0RH equal to 100%, then, 8959.010 9101606 0 cmo cm sc csf f (6-9) sstt can be estimated by the following equation: 5.0 1 2 0 350 1 t s tt h h t s tt s tt s (6-10) Where u A hc2 = the notational size of member (in mm), where Ac is the cross-sectional area (mm2) and u is the perimeter (mm) of th e member circular cross section (2 r) in contact with the atmosphere. H is equal to 1.5 for 6 12in cylinder. 0h is equal to 100 mm. 1t is equal to 1 day. Therefore, the above equation can be simplified as follows: 5.0 23.203 t t t s (6-11) The shrinkage strains at 91 days for all the c oncrete mixtures invest igated in this study were compared with the calcula ted results using ACI 209 model a nd C.E.B-F.I.P model in Figure 6-7. The hollow circle indicates the predicti on by C.E.B-F.I.P model, and solid black dot represents the prediction by ACI 209 model. As shown in Figure 6-7, C.E.B-F.I.P model gives encouraging prediction in comparison with the experimental data, while ACI-209 model provides extreme over-estimation.

PAGE 139

140 y = x 0.00E+00 1.00E-04 2.00E-04 3.00E-04 4.00E-04 5.00E-04 0.00E+001.00E-042.00E-043.00E-044.00E-045.00E-04 Predicted Shrinkage StrainShrinkage Strain from Experiment ACI 209 model C.E.B-F.I.P model Figure 6-7 Comparison between the shrinkage st rain at 91 days and the shrinkage strain calculated by ACI 209 model and C.E.B-F.I.P model 6.4 Prediction of Ultimate Shrinkage Strain Shrinkage of concrete lasts for a long time w ith decreasing shrinkage rate. Generally, it is assumed that concrete will shrink with time to a limiting value, called ultimate shrinkage strain, which is a very important parameter in concrete structural design. In th is study, an asymptotic equation, given as follows, was used to fit the experimental data. t t t sh (6-12) As can be seen from the above equation, shri nkage strain will approach its limiting value as time goes to infinite value. Thus, is the ultimate shrinkage strain. Curve-fitting regression analys is was performed using Least Square Method, which is detailed as follows:

PAGE 140

1416.4.1 Least Square Method of Curve-fitting The method of least squares was used when f itting data. The model sel ected to relate the response data to the predictor data with two coefficients is given as follows: x x y (6-13) Where and are two constitutive parameters to be determined from curve fitting process; x is time variable, and y is response variable, and it is the creep strain in this study. The goal of the fitting process is to estimat e the "true" but unknown coefficients of the model. To obtain the coefficient estimates, the residual for the ith data point, i r defined as the difference between the observed response value i y and the fitted response valuei y and identified as the error associated with the data is computed by yyr (6-14) Then, the summed square of residuals is given by n i i y i y n i i rS 1 2 1 2 (6-15) Where n is the number of data points included in the fit, and S is the sum of squares error estimate. Th e least squares method minimizes the summed square of residuals, and then the optimized coefficients will be achieved. Since the model used to fit the data is the ratio of two polynom ials, it is a nonlinear equation. Therefore Nonlinear Leas t Squares Method was used to do cu rve-fitting anal ysis in this study. In matrix form, nonlinear models are given by the formula

PAGE 141

142 Xy f (6-16) Where y is an n-by-1 vector of responses, f is a function of and X, is a m-by-1 vector of coefficients, x is the n-by-m design matrix for the model, and is an n-by-1 vector of errors. Unlike linear models, the coefficients are es timated using simple matrix techniques; an iterative approach is used to estimate coefficients of nonlinear model. The fitted response value is given by bXy f (6-17) and involves the calculation of the Jacobian of f( X,b), which is defined as a matrix of partial derivatives taken with respect to the coeffici ents. Then, the coefficients are adjusted and determination was made as to whether the fit improves. The direction and magnitude of the adjustment depend on the fitting algorithm. In this study, Trust-region algorithm was used because it can solve difficult nonlin ear problems more efficiently th an the other algorithms, and it represents an improvement over the popular Levenberg-Marquardt algorithm. Because nonlinear models can be particularly sensitive to the starting points, the initial values of the estimates should be carefully de fined to guarantee the convergence of regression analysis. 6.4.2 Evaluation Methods on the Goodness of Fit In this study, after fitting data with the model, the goodness of fit was evaluated by graphical illustration, such as a visual examination of the fitted curve and residual plot, and

PAGE 142

143 numerical measures, such as goodness of fit statis tics confidence, standard error, and regression correlation coefficient (R2). In doing so, graphical illustration allows us to view the entire data set at once, and they can easily display a wide range of relationships between the model and the data. The numerical measures are more narrowly focused on a particular aspect of the data and often try to compress that information into a single number. In the following content, the methods used to evaluate the goodness of fit in this study are described briefly. The sum of squares due to error (SSE) This statistic, also called the summed square of residuals, measures the total deviation of the response values from the fit to the response values. It is usually labeled as SSE. n i i y i y i w SSE 1 2 (6-18) A value closer to 0 indicates a better fit. R-square R-square, also called the square of the multiple correlation coefficient and the coefficient of multiple determination, is th e square of the correlation between the response values and the predicted response values. It measures how successful the fit is in explaining the variation of the data. R-square is defined as the ratio of the sum of squares of the regression (labeled as SSR) and the total sum of squares (labeled as SST), also called the sum of squares about the mean. SSR is defined as n i iiyywSSR1 2 (6-19) And SST is defined as

PAGE 143

144 n i iiyywSSESSRSST1 2 (6-20) Then, according to the definition, R-square is expressed as SST SSE SST SSESST SST SSR R 12 (6-21) R-square can take on any value between 0 and 1, with a value closer to 1 indicating a better fit. Root mean squared error (RMSE) RMSE is also known as the fit standard error and the standard error of the regression MSEsRMSE (6-22) Where MSE is the mean square error or the residual mean square v SSE MSE (6-23) A RMSE value closer to 0 indicates a better fit. Confidence and Prediction Bounds Confidence and prediction bounds define the lo wer and upper values of the associated interval, and define the width of the interval, which indicates how uncertain we are about the fitted coefficients, the predicted observation, or the predicted fit. Confidence bounds were obtained through regressi on analysis for the fitted coefficients, and prediction bounds for the fitted function. In this study, the confidence bounds are given numerically, while the prediction bounds are displayed graphically. In this study, the bounds are defi ned with a certainty of 95%. In this study, the regression analysis was car ried out using statisti c analysis software, GraphPad Prism, programmed by Gr aphPad Prism software Inc.

PAGE 144

1456.4.3 Predicted Results The results of regression analysis using E quation 6-12 are presented in Table 6-5. The ultimate shrinkage strains predicted for 14 concrete mixtures, which are represented the values for are summarized in Table 6-5. Graphically, predicted ultimate shrinkage strain based on experimental data was compar ed with the predictions made by original ACI-209 model and C.E.B-F.I.P model in Figure 6-8. As can be seen from the graphical plots as well as Table-6-5, the predicted ultimate shrinkage strains,, for fourteen concrete mixtures vary from 0.0002 to 0.00041, which is considerable less than the pr edicted values by ACI 209 model and C.E.B-F.I.P model. 0.00E+00 1.00E-04 2.00E-04 3.00E-04 4.00E-04 5.00E-04 6.00E-04 0.00E+002.00E-044.00E-046.00E-04 Calculated by C.E.B-F.I.P model and ACI modelUltimate Shrinkage Strain by Curve-fitting ACI 209 model C.E.B-F.I.P model Figure 6-8 Comparison among the ultimate shrinkag e strains from curve-fitting, CEB-FIP model and ACI 209 model As shown in Table 6-5, has a value close to 1 for all concrete mixtures, while -value is significantly different between fly as h concrete and slag concrete. has an average value of

PAGE 145

146 1.04, and has an average value of 30.0. As can be seen from Table 6-5, -value for the specimens moist-cured for 7 days is higher than that for the sp ecimens moist-cured for 14 days. This is due probably to the fact that the evapor ation rate of free water concrete becomes slower at a longer curing age when the concrete is denser. At last, based on the 14 concrete mixtures inve stigated in this study, the ultimate shrinkage strain predicted through curve-fitting the three-parame ter model to experimental data is less than 3.510-4 for normal-weight aggregate concrete, and 4.510-4 for lightweight aggregate concrete. Table 6-5 Results of regression analysis for pr ediction of shrinkage st rain using Equation 6-12 Mix SE SE SE R2 SSE 1F 0.983 1.122 0.024 0.049 2.66E-04 2.27E-04 2.70E-06 4.31E-06 31.18 31.10 1.804 3.117 0.9997 0.9992 1.20 10-6 1.67 10-6 2F 1.027 1.137 0.021 0.042 3.39E-04 3.21E-04 1.51E-06 3.35E-06 16.48 19.13 0.649 1.515 0.9998 0.9994 1.27 10-6 1.23 10-6 3F 1.011 0.920 0.022 0.031 3.03E-04 2.85E-04 1.69E-06 3.89E-06 20.05 31.74 0.869 2.545 0.9998 0.9994 1.19 10-6 1.81 10-6 4F 0.867 0.855 0.013 0.032 3.44E-04 3.24E-04 2.74E-06 8.93E-06 27.84 32.44 1.530 3.910 0.9999 0.9990 1.10 10-6 2.45 10-6 5S 0.996 0.812 0.045 0.026 2.46E-04 2.29E-04 1.83E-06 1.86E-06 12.52 20.88 1.005 1.427 0.9992 0.9994 2.02 10-6 1.50 10-6 6S 1.227 1.332 0.041 0.125 2.16E-04 1.93E-04 0.86E-06 1.54E-06 8.172 6.511 0.432 0.761 0.9997 0.9985 1.16 10-6 2.20 10-6 7S 1.196 0.910 0.028 0.034 2.55E-04 2.40E-04 0.93E-06 2.13E-06 11.37 18.89 0.449 1.429 0.9998 0.9993 0.98 10-6 1.74 10-6 8S 1.325 1.232 0.087 0.089 2.43E-04 2.20E-04 1.82E-06 2.52E-06 7.822 11.61 0.789 1.406 0.9989 0.9984 2.42 10-6 2.56 10-6 9LF 0.836 1.018 0.030 0.030 3.95E-04 3.49E-04 3.09E-06 4.89E-06 20.53 31.49 1.220 2.756 0.9996 0.9992 2.11 10-6 2.51 10-6 10LS 1.055 0.851 0.026 0.066 4.22E-04 3.96E-04 3.30E-06 7.12E-06 21.74 21.04 1.349 2.796 0.9983 0.9995 4.42 10-6 2.05 10-6 2GF 1.105 0.053 2.83E-04 3.39E-06 18.09 1.632 0.9994 2.16 10-6 3GF 0.832 0.052 2.62E-04 3.16E-06 48.32 2.263 0.9999 5.93 10-6 5GS 0.897 0.010 2.18E-04 1.96E-06 18.44 1.661 0.9988 2.35 10-6 7GS 0.668 0.045 2.19E-04 5.61E-06 31.11 5.619 0.9976 3.17 10-6 6.5 Summary of Findings This chapter presents the results of shrinkage tests on the concrete mixtures investigated in this study. The summary of this chapter and major findings are provided as follows:

PAGE 146

147 (1) Fly ash concrete mixtures had slightly highe r shrinkage strain at 91 days than slag concretes. This is due probabl y to the slow hydration rate of fly ash in comparison with that of slag. As a result of slower rate of hydration, there is more free water evaporating from the interior concrete out, which can cause concrete to shrink more. Thus, it is recommended that using a longer wet curing time would be helpful to reduce shrinkage of fly ash concrete. (2) Water content has a significant effect on dryi ng shrinkage strain of concrete. The higher the water content, the more the concrete tends to shrink. However, no clear trend can be seen on the effects of water to cementitious materials ratio on shrinkage of concrete. (3) For the four concrete mixtures with Georgia granite aggregate, shrinkage strain is slightly lower than the four corresponding concrete mixtures with Miami Oolite limestone aggregate. Lightweight aggregate concrete shrinks more than normal weight aggregate concrete. This might be explained by their difference in elastic modulus. The concrete with higher elastic modulus w ould have a stronger resistance to the movement caused by shrinkage of cement paste. (4) For the concretes tested, ther e appeared to be a relations hip between the compressive strength ('cf) at the age when shrinkage test wa s started and the shrinkage strain (sh ) at 91 days as follows: '0001.0 0005.0cf e sh Where 'cf is in unit of psi. (5) For the concretes tested, ther e appeared to have a relati onship between elastic modulus (cE) at the age when shrinkage test was started and the shrinkage strain (sh ) at 91 days as follows: c shE e 7102 0007.0 Where cE is in unit of psi. (6) According to the shrinkage test results from this study, th e C.E.B-F.I.P model (as shown in Equation 6-6) appeared to give better predictions than the ACI 209 model (as shown in Equation 6-3). Using ACI 209 model may resu lt in over-estimation of the ultimate shrinkage strain. (7) For the concrete investigated in this study, the ultimate shrinkage strain ranged from 1.93 10-4 to 3.64 10-4 for the concretes with Miami Oolite limestone aggregate; from 2.18 10-4 to 2.83 10-4 for the concretes with Georgia granite aggregate; and from 3.49 10-4 to 4.22 10-4 for the concretes with Stalite lightweight aggregate concrete.

PAGE 147

148 CHAPTER 7 ANALYSIS OF CREEP TEST RESULTS 7.1 Introduction This chapter presents the results from creep tests on the fourteen c oncrete mixes evaluated in this study. The effects of various factors on creep behavior of concrete were analyzed. Empirical equations relating creep to other fundamental properties, such as compressive strength and elastic modulus, were established through regression analysis. Evaluation was made on C.E.B-F.I.P model and ACI 209 model for their e ffectiveness and accuracy in creep prediction. Ultimate creep strain was approximated using a three-parameter asymptotic equation to fit experimental data, and ultimate creep coefficien t was computed using ultimate creep strain divided by instantaneous strain. 7.2 Analysis of Creep Test Results The measured and calculated results from the creep tests on the fourteen concrete mixes evaluated in this study were presented in Tabl e B-1 in Appendix B. The results presented include the total strain, shrinkage strain, creep st rain, elastic strain, creep coefficient and creep modulus at various loading ages. 7.2.1 Effects of Curing Condition s on Creep Behavior of Concrete As shown in Figure 7-1 and Figure 7-2, the curi ng condition has a significant effect on the creep behavior of such concrete mixtures as Mix-1F, Mix-2F, Mix-3F, and Mix-4F. Generally, the concrete specimens moist-cured for 14 days ha d creeping strains which were less than those moist-cured for 7 days by more than 13 percen t. This observation applies to the specimens loaded at both 40% of compressive strength and 50% of compre ssive strength at the two given loading ages. Also, it is of significance to men tion that, for ultra-high strength concrete, the effect of curing condition on creep strain is extremely important For example, the specimens

PAGE 148

149 from Mix-1F moist-cured for 14 da ys have creep strain at 91 days over 25 percent less than those moist-cured for 7 days. This is due probably to its high cementitious ma terials content, 1000 lbs per cubit yard, and low water to cementitious ratio of 0.24. Thus, long-term moist curing condition is needed to make cement hydration as complete as possible. The tremendous effects of curing conditions on creep behavior also extend to the concrete mixtures with lightweight aggregate, such as Mix-9LF and Mix-10LS. For example, the creep strain of Mix-9LF moist-cured for 14 days a nd loaded at 50% of compressive strength is 0.000749, which is 29.8% lower than that of Mix9LF moist-cured for 7 days and loaded at the same loading level. The creep strain of Mix-10LS moist-cured for 14 days and loaded at 50% of compressive strength is 0.000776, which is 47.3% lower than that of Mi x-10LS moist-cured for 7 days and loaded at 50% of its compressive strength. However, no substantial effect of curing c ondition on creep strain was seen from the concrete mixtures containing gr ound granulated blast-furnace sl ag as mineral additives. For example, the creep strain of Mix-5S moist-cured fo r 14 days is nearly identical to that of Mix-5S moist-cured for 7 days. This similar situation can also be seen from Mix-6S, Mix-7S and Mix8S. The cause can be attributed probably to the f act that the slag concretes nearly develop their compressive strength fully in 14 days. That is to say, in comparison with the compressive strength at 14 days, slag concrete mixtures ha ve no significant increase in compressive strength at age of 28 days. That means the specimens mois t-cured for 14 days has no significant change in microstructure in comparison with those moistcured for 7 days. Thus, creep strains of slag concretes obtained und er two different curing conditions show no significant difference.

PAGE 149

150 0.00E+00 2.00E-04 4.00E-04 6.00E-04 8.00E-04 1.00E-03 1.20E-03 1.40E-03 1F2F3F4F5S6S7S8S9LF10LS MixtureCreep Strain at 91 days 7-day moist curing 14-day moist curing Figure 7-1 Effects of curing condition on creep of concrete loaded at 40% of compressive strength 0.00E+00 2.00E-04 4.00E-04 6.00E-04 8.00E-04 1.00E-03 1.20E-03 1.40E-03 1.60E-03 1F2F3F4F5S6S7S8S9LF10LS MixtureCreep Strain at 91 days 7-day moist curing 14-day moist curing Figure 7-2 Effects of curing condition on creep of concrete loaded at 50% of compressive strength

PAGE 150

151 7.2.2 Effects of Loading Condition on Creep Behavior of Concrete The effects of stress level on creep of the conc retes investigated in this study are presented in Figure 7-3 and Figure 7-4. As shown in Figure 7-3 and Figure 7-4, th e concrete specimens loaded at 50% of compressive strength develop c onsiderably higher creep strain than those loaded at 40% of compressive strength at loading age, and the signi ficant effects of stress level on creep strain can be seen from both the normal weight aggregate concretes and lightweight aggregate concretes. As shown in Table 7-1, for the concrete mixtur es with fly ash, after 7 days moist curing the specimens of Mix-1F loaded at 50% of compressi ve strength have creep strain of 0.00093, nearly 20% higher than those loaded at 40% of compressive strength. The 7-day moist-cured specimens from Mix-2F loaded at 40% of compressive stre ngth have creep strain at 91 days 18.5 percent less than those loaded at 50% of compressive st rength. For Mix-3F and Mi x-4F, creep strain of specimens moist-cured for 7 days and loaded at 40% of compressive strength is 31.6% and 22.7% lower than those of the same concretes moist-cured under the same condition but loaded at 50% of compressive strength. For the concrete mixtures with slag, creep st rains of Mix-5S, Mix-6S, Mix-7S and Mix-8S moist-cured for 7 days and loaded at 50% of compressive strength are 22.8%, 11.9%, 17.2%, and 16.3% higher than those of the same correspond ing concretes cured under the same condition but loaded at 40% of compressive strength. Significant effects of loading c onditions on creep behavior can also be observed from the specimens moist-cured for 14 days. For the fly as h concretes, the specim ens of Mix-1F, Mix-2F, Mix-3F and Mix-4F moist-cured for 14 days and loaded at 50% of compressive strength creep 12.7%, 22.1%, 18.5% and 18.5% higher than thos e of the same corresponding concretes loaded

PAGE 151

152 at 40% of compressive strength co rrespondingly. For slag concretes, the creep strains of Mix-5S, Mix-6S, Mix-7S and Mix-8S moist-cured for 14 da ys and loaded at 50% of compressive strength are 18.3%, 16.1%, 16.4% and 18.6% higher than those of the same corresponding concretes loaded at 40% of compressive strength. In addition, significant effect of loading condition on creep beha vior can be seen from the concrete mixtures with granite aggregate. For example, in comp arison with the specimens loaded at 40 percent of compressive strength, the creep strain of the specimens loaded at 50 percent of compressive strength is over 23% higher. Similar observation can also be seen from the concrete mixtures with lightweight aggregate. 0.00E+00 2.00E-04 4.00E-04 6.00E-04 8.00E-04 1.00E-03 1.20E-03 1.40E-03 1.60E-03 1F2F3F4F5S6S7S8S9LF10LS MixtureCreep Strain at 91 days 40% of compressive strength 50% of compressive strength Figure 7-3 Effects of stress level on creep of concrete moist-cured for 7 days

PAGE 152

153 0.00E+00 2.00E-04 4.00E-04 6.00E-04 8.00E-04 1.00E-03 1.20E-03 1.40E-031F 2F 3 F 4 F 5S 6 S 7 S 8 S 9 L F 1 0 LS 2GF 3GF 5 GS 7 GSMixtureCreep Strain at 91 days 40% of compressive strength 50% of compressive strength Figure 7-4 Effects of stress level on creep of concrete moist-cured for 14 days 7.2.3 Effects of Aggregate Types on Creep Behavior of Concrete The effect of two different normal coarse aggr egates on creep behavior was investigated on four typical concrete mixtures i.e. Mix-2F, Mix-3F, Mix-5S and Mix-7S. These mixes used a Miami Oolite limestone as coarse aggregate. The four concrete mixtures with Georgia granite aggregate were labeled as Mix2GF, Mix-3GF, Mix-5GS, and Mi x-7GS. The creep behavior of these concrete mixtures was compared under the same curing conditions and loading conditions. As shown in Figures 7-5 through 7-8, the comp arison between Mix-2F and Mix-2GF, Mix-3F and Mix-3GF, Mix-5S and Mix5GS, and Mix-7S and Mix-7GS indicate that Mix-2GF, Mix3GF, Mix-5GS, and Mix-7GS creep slightly mo re than the correspondi ng Mix-2F, Mix-3F, Mix5S and Mix-7S for all loading conditions. This agrees with the findings from the study by G.E. Troxell et al [G.E. Troxell et al, 1958]. He carried out the study on the effect of six different types of aggregate on creep behavior of concrete The results indicate that the concrete with

PAGE 153

154 limestone aggregate has the lowest creep strain in comparison with the concretes with other types of coarse aggregates, including quartz, granite, gravel, basalt and sandstone. In addition, the concrete mixt ures with lightweight aggregat e, such as Mix-9LF and Mix10LS, do not creep as much as the concrete mixtur es with normal weight aggregate. As can be seen from Table 7-1, Mix-9LF and Mix-10LF deve lop much less creep stra in than the concrete mixtures, such as Mix-2F, 3F, 4F, 5S, 6S, 7S, and 8S, even though the compressive strengths of Mix-9LF and Mix-LS are considerab le lower than those of concrete mixtures with normal weight aggregate. These results agree with the conclu sion made by A.M. Neville [A.M. Neville, 1996], which stated that, as a general rule, the creep of structural quality lightwe ight aggregate concrete is about the same as that of concrete made with ordinary aggregate. 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 0102030405060708090100 Time (days)Creep Strain Georgia granite-40%-28-day curing Georgia granite-50%-28-day curing Miami Oolite limestone-40%-28-day curing Miami Oolite limestone-50%-28-day curing Figure 7-5 Effects of aggregate t ype on creep behavior of Mix-2F

PAGE 154

155 0.00E+00 2.00E-04 4.00E-04 6.00E-04 8.00E-04 1.00E-03 1.20E-03 0102030405060708090100 Time (days)Creep Strain Georgia granite-40%-28-day curing Georgia granite-50%-28-day curing Miami Oolite Limestone-40%-28-day curing Miami Oolite limestone-50%-28-day curing Figure 7-6 Effects of aggregate t ype on creep behavior of Mix-3F 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 0102030405060708090100 Time (days)Creep Strain Georgia granite-40%-28-day curing Georgia granite-50%-28-day moist curing Miami Oolite limestone-40%-28-day curing Miami Oolite limestone-50%-28-day curing Figure 7-7 Effects of aggregate t ype on creep behavior of Mix-5S

PAGE 155

156 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 0102030405060708090100 Time (days)Creep Strain Georgia granite-40% loading level Georgia granite-50% loading level Miami Oolite limestone-40% loading level Miami Oolite limestone-50% loading level Figure 7-8 Effects of aggregate t ype on creep behavior of Mix-7S 7.2.5 Effects of Water to Cement Rati o and Air Content on Creep Strain The main component of creep in concrete is from creep of the hydrat ed cement paste. Creep is related to internal movement of absorb ed or intracrystalline water, i.e. to internal seepage [A.M.Neville, 1996]. Gl ucklichs study has shown that concrete from which all evaporable water has been removed exhibits pr actically no creep [J. Glucklich, 1962]. Thus, water to cementitious materials ratio gives a signi ficant effect on the magnitude of creep strain. Also, voids in the concrete play a critical role in influencing cr eep behavior of concrete because internal seepage of water from the absorbed layers to voids such as capillary voids is quite possible. A.M.Neville [A.M.Neville, 1996] stated that creep appears to be a function of the relative amount of the unfilled space, and that the voids in the gel govern creep in concrete. The effects of water to cementitious materials ratio and air content on creep of concrete are illustrated in Figures 7-9 through 712. From these figures, it can be seen that creep of concrete

PAGE 156

157 increases as water to cementitious materials ratio increases. It can also been seen from these figures that the creep strain in creases with increase of air cont ent of fresh concrete, even though air content of fresh concrete may not be directly related to the void content of hardened concrete. 7.2.6 Relationship between Compre ssive Strength and Creep Strain It is always desirable in practice to find th e relationship between co mpressive strength and creep strain. If a simple relationship can be found between compressive st rength and creep, it is not necessary to consider the effect of type of cement, aggregate content and aggregate type, water to cement ratio, air content and age on cr eep behavior separately In addition, possible accurate estimation on creep strain based on characteristic strength of concrete will make us free from time-consuming creep test. In Figure 7-13, compressive streng th of concrete at 14 days is plotted against creep strain at 91 days for the concretes moist-cured for 7 da ys and loaded at 40% and 50% of compressive strength. In Figure 7-14, the compre ssive strength of conc rete at 28 days is plotted against creep strain at 91 days for the conc retes moist-cured for 14 days an d loaded at 40% and 50% of compressive strength. As seen from Figure 7-13 and Figure 7-14, the creep strain decreases with increase of compressive strength of concrete. Regression analysis was performed to determine the relationship between compressive strength and creep strain at 91 days using following simple linear function c cf91 (7-1) The results of the regression analys is are presented in Table 7-2. As shown in Table 7-2, loading condition has a significant influence on the slope and interception of the above linear equation, while curing age ha s nearly no effect on the slope and interception. That is to say, the relationship between compressive st rength and creep strain

PAGE 157

158 obtained under the load at 40% of compressive strength can be expressed as one single linear equation regardless of what curi ng condition was applied to the specimens. The same conclusion also applies to concrete specimens loaded at 50% of compressive strengt h. The above hypothesis is confirmed by the results of re gression analysis given in Table 7-1, and also shown in Figure 715. In addition, instantaneous stra ins of normal-weight aggregate concrete are plotted against compressive strength of concrete at corresponding curing ages in Figure 7-16. It indicates that instantaneous strain measured in creep test in creases with increase of compressive strength of concrete. 0.00E+00 2.00E-04 4.00E-04 6.00E-04 8.00E-04 1.00E-03 1.20E-03 1.40E-03 0.200.250.300.350.400.450.50 Water to Cementitious Materials RatioCreep Strain at 91 days high air content low air content Figure 7-9 Effects of water to cementitious materi als ratio and air content on creep of concrete moist-cured for 7 days and loaded at 40% of compressive strength

PAGE 158

159 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 0.200.250.300.350.400.450.50 Water to Cementitious Materials RatioCreep Strain at 91 days high air content low air content Figure 7-10 Effects of water to cem entitious materials ratio and ai r content on creep of concrete moist-cured for 7 days and loaded at 50% of compressive strength 0.00E+00 2.00E-04 4.00E-04 6.00E-04 8.00E-04 1.00E-03 1.20E-03 0.200.250.300.350.400.450.50 Water to Cementitious Materials RatioCreep Strain at 91 days high air content low air content Figure 7-11 Effects of water to cem entitious materials ratio and ai r content on creep of concrete moist-cured for 14 days and loaded at 40% of compressive strength

PAGE 159

160 0.00E+00 4.00E-04 8.00E-04 1.20E-03 1.60E-03 2.00E-03 0.200.250.300.350.400.450.50 Water to Cementitious Materials RatioCreep Strain at 91 days high air content low air content Figure 7-12 Effects of water to cem entitious materials ratio and ai r content on creep of concrete moist-cured for 14 days and loaded at 50% of compressive strength Table 7-1 Regression analysis on relationship between compressive strength and creep strain using Equation 7-1 Curing condition Loading condition 95% Confidence Interval 95% Confidence Interval R2 Sy.x 40% -8.57E-08 -1.19E-07 ~ -5.29E-08 1.54E-03 1.28E-03 ~ 1.81E-03 0.69 8.38E-05 7-day moist curing 50% -1.20E-07 -1.62E-07 ~ -7.75E-08 1.98E-03 1.65E-03 ~ 2.32E-03 0.72 1.08E-04 40% -9.27E-08 -1.23E-07 ~ -6.29E-08 1.59E-03 1.35E-03 ~ 1.84E-03 0.70 8.70E-05 14-day moist curing 50% -1.11E-07 -1.46E-07 ~ -7.62E-08 1.95E-03 1.67E-03 ~ 2.24E-03 0.71 1.01E-04 40% -8.99E-08 -1.10E-07 ~ -6.94E-08 1.57E-03 1.41E-03 ~ 1.74E-03 0.70 8.33E-05 All curing conditions 50% -1.13E-07 -1.39E-07 ~ -8.80E-08 1.95E-03 1.75E-03 ~ 2.16E-03 0.71 1.03E-04

PAGE 160

161 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 1.80E-03 400050006000700080009000100001100012000 Compressive Strength at loading ageCreep Strain at 91 days 7-day-40% 7-day-50% Figure 7-13 Relationship between compressive strength and creep stra in of concrete moist-cured for 7 days 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 1.80E-03 50006000700080009000100001100012000 Compressive Strength at loading ageCreep Strain at 91 days 14-day-40% 14-day-50% Figure 7-14 Relationship between compressive strength and creep stra in of concrete moist-cured for 14 days

PAGE 161

162 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 1.80E-03 400050006000700080009000100001100012000 Compressive Strength (psi)Creep Strain at 91 days 40% loading level 50% loading level Figure 7-15 Relationship between compressive strength and creep st rain of concrete under all curing conditions 0.00E+00 2.00E-04 4.00E-04 6.00E-04 8.00E-04 1.00E-03 1.20E-03 50006000700080009000100001100012000 Compressive Strength (psi)Instantaneous Strain from Creep Test 40% of compressive strength 50% of compressive strength Figure 7-16 Relationship of compressi ve strength to instantaneous st rain measured in creep test

PAGE 162

163 7.3 Creep Coefficient Creep coefficient, which is calc ulated by dividing creep strain by elastic strain, is a very important parameter in prestressed concrete design. Creep coefficient is si gnificantly affected not only by those factors influencing creep strain, but also by the el astic property of concrete. 7.3.1 Effects of Loading Conditions on Creep Coefficient For the specimens moist-cured for 7 days, the creep coefficients obtained from two different stress levels are plotte d in Figure 7-17 for ten concrete mixtures. It shows that two different stress levels have nearly no effect on the creep coefficien t of all the concrete mixtures. The same observation can be seen from the specime ns moist-cured for 14 days as well, as shown in Figure 7-18. In this study, two stress levels includ e 40% of compressive strength and 50% of compressive strength. Thus, the conclusion can be arrived that the ratio of creep strain to instantaneous strain of concretes investigated in this study is pr oportional to the stress applied up to 50% of compressive stre ngth at loading age. 7.3.2 Effects of Curing Condi tions on Creep Coefficient Curing conditions have some effects on creep coefficient. As shown in Figure 7-19, the effects of curing conditions on creep coefficients of Mix-1F, Mix-2F, and Mi x-3F are substantial. For example, the creep coefficient of Mix-1F mois t-cured for 14 days is 0.81 at 91 days, which is 35.8% lower than that of Mix-1 moist-cured for 7 days. Also, the creep coefficients of Mix-2F and Mix-3F moist-cured for 14 days are 23.9% and 17.7% lowe r than those of the same corresponding concretes mo ist-cured for 7 days. However, for some concrete mixtures, such as Mix-6S, Mix-7S, Mix-8S, and Mix-4F, the effects of curing conditions on creep coefficient are not very appreciable. For instance, the creep co efficients of Mix-6S, Mix-7S, Mix-8S and Mix4F moist-cured for 14 days are ju st about 10% lower than those of them moist-cured for 7 days.

PAGE 163

164 The cause can be attributed to the fact th at there was not too much additional strength development from the age of 14 days to the age of 28 days for the slag concretes. -0.50 0.00 0.50 1.00 1.50 2.00 1F2F3F4F5S6S7S8S9LF10LS MixtureCreep Coefficient at 91 days 40% of compressive strength 50% of compressive strength Difference Figure 7-17 Effects of stress leve l on creep coefficient of concrete moist-cured for 7 days -0.50 0.00 0.50 1.00 1.50 2.001F 2 F 3 F 4 F 5S 6S 7 S 8S 9 LF 10 L S 2 GF 3GF 5GS 7 GSMixtureCreep Coefficient at 91 days 40% of compressive strength 50% of compressive strength Difference Figure 7-18 Effects of stress leve l on creep coefficient of concrete moist-cured for 14 days

PAGE 164

165 The effects of curing condition on creep coeffici ent of lightweight aggregate concrete are very significant. For instance, the creep coeffici ent of Mix-9LF moist-cure d for 14 days is about 1.14, nearly 18% lower than that of Mix-9LF moist-cured for 7 days. Also, the specimens of Mix-10LS moist-cured for 14 days has creep coefficient of 1.13, which is over 42% lower than 1.61, creep coefficient of Mix-6 moist-cured for 7 days. Thus, apparently, longer curing time can decrease creep coefficient tremendously for lightweight aggregate concrete. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 1F2F3F4F5S6S7S8S9LF10LS MixtureCreep Coefficient at 91 days 7-day moist curing 14-day moist curing Figure 7-19 Effects of cu ring condition on creep coefficient of concrete 7.3.3 Effects of Water Cont ent on Creep Coefficient Since water content of fresh concrete affect significantly drying creep of concrete, they should have considerable effects on creep coeffici ent as well. As can be seen from Figure 7-20, water content of fresh concrete have significant effects on creep coefficient of concrete at 91 days. Creep coefficient at 91 days increases as water content of fresh concrete increases.

PAGE 165

166 0.00 0.50 1.00 1.50 2.00 2.50 100150200250300350400 Water Content (lbs/yard3)Creep Coefficient at 91 days Miami Oolite limestone Georgia granite Stalite lightweight aggregate Figure 7-20 Effects of wa ter content on creep coefficient at 91 days 7.3.4 Effects of Compressive Strength at Loading Age on Creep Coefficient As shown in Table 7-1, the higher the compress ive strength of concrete is at the loading age, the lower the creep coeffici ent is. For example, for the concrete mixtures with Miami Oolite limestone aggregate, Mix-1 has the highest comp ressive strength, and it has the lowest creep coefficient. Also, it is of great importance to see that the creep coefficient is not affected by the loading conditions, i.e. the creep coefficient obtained under the loading condition of 40% of compressive strength is iden tical to that obtained under th e loading condition of 50% of compressive strength. To find out how the compressive strength of conc rete at loading age is related to the creep coefficient at 91 days, compressive strength at loading age was plotted against corresponding creep coefficient at 91 days in Figure 7-21 and Fi gure 7-22, for specimens loaded at 14 days and

PAGE 166

167 28 days, respectively. Then linear regression analysis using Equation 7-2 was performed, and the analyzed results are displayed in Table 7-2. c cf (7-2) Where c = creep coefficient at 91 days; fc = compressive strength; and = the slope and interception of linear equation. Table 7-2 Regression analysis on re lationship of compressive strength to creep coefficient using Equation 7-2 Curing condition 95% Confidence Interval 95% Confidence Interval R2 Sy.x 14-day curing -2.02E-04 -2.39E-04 ~ -1.64E-04 3.016 2.717 ~ 3.316 0.9041 0.0951 28-day curing -2.06E-04 -2.43E-04 ~ -1.69E-04 3.077 2.774 ~ 3.379 0.8855 0.1071 All curing conditions -2.03E-04 -2.28E-04 ~ -1.79E-04 3.042 2.842 ~ 3.242 0.8919 0.0999 As can be seen from Table 7-2 as well as Figure 7-21 and Figure 7-22, compressive strength of concrete at loading age is nearly linearly related to the creep coefficient at 91 days. This situation is true for the specimens under two different curing conditions. Also, it is to be noted that the slope and intercep tion of the linear regres sion equations are nearly identical to one another for the specimens under tw o different curing conditions. That is to say, once compressive strengths of specific concrete mixtures are given, the creep coefficient can be computed using the linear relationship between compre ssive strength and creep coeffici ent at 91 days regardless of what curing condition was applied to the specimens. Therefore, linear regression analysis was car ried out on the experimental data obtained from both curing conditions, and th e analyzed results are plotted in Figure 7-23 and presented in Table 7-2 as well. As can be seen from Table 72, the slope and intercep tion of linear regression equation from combined analysis are approxi mately equal to the average of slopes and interceptions from separate analyses.

PAGE 167

168 0.00 0.50 1.00 1.50 2.00 2.50 2000400060008000100001200014000 Compressive strength at 14 days (psi)Creep Coefficient Second phase First phase Figure 7-21 Relationship between compressive strength and creep coefficient for specimens loaded at 14 days 0.00 0.50 1.00 1.50 2.00 2.50 400060008000100001200014000 Compressive Strength at 28 Days (psi)Creep Coefficient Second phase First phase

PAGE 168

169 Figure 7-22 Relationship between compressive strength and creep coefficient for specimens loaded at 28 days 0.00 0.50 1.00 1.50 2.00 2.50 400060008000100001200014000 Compressive Strength (psi)Creep Coefficient at 91 days Limestone Granite Figure 7-23 Relationship between compressive strength at loading age and corresponding creep coefficient at 91 days 7.3.5 Relationship between Elastic Modulus at Loading Age and Creep Coefficient After realizing the close relati onship between compressive strength and creep coefficient, it is not difficult to note that because, for a gi ven concrete, compressive strength and elastic modulus is related, creep coefficient and elastic modulus should be related as well. As shown in Figure 7-24, elastic modulus was plotted against creep coefficient at 91 days for the concrete with normal-weight aggregate. A linear regression analysis was performed using Equation 7-3. c cE (7-3) The results of the regression analysis are show n in Table 7-3. As can be seen from Figure 7-24, for the normal-weight aggregate concrete, creep coefficient at 91 days is linearly related to

PAGE 169

170 the elastic modulus at the loading age, while for lightweight aggregate conc rete creep coefficient can not be related to elastic modulus using the linear equation from normal-weight aggregate concrete. More data from creep test on lightweight a ggregate concrete are needed to establish reliable relationship between el astic modulus and creep coeffici ent for lightweight concrete. In addition, creep coefficient at 91 days wa s plotted against the ratio of compressive strength and elastic modulus in Figure 7-25. It indicates that creep coefficient at 91 days is linearly related to the ratio of compressive strength to elastic modulus of concrete at loading age. A linear regression analysis was performed to relate creep coefficient to the ratio of compressive strength to elastic modulus by the following equation: c c cE f (7-4) The results of the regression analys is are presented in Table 7-4. 0.00 0.40 0.80 1.20 1.60 2.00 2.40 2.00E+063.00E+064.00E+065.00E+066.00E+067.00E+068.00E+06 Elastic Modulus at Loading Ages (psi)Creep Coefficient at 91 days Normal weight aggregate Lightweight aggregate Figure 7-24 Effects of Elastic modulus at lo ading age on creep coefficient at 91 days

PAGE 170

171 0.00 0.50 1.00 1.50 2.00 2.50 00.00050.0010.00150.0020.00250.003 fc/ECreep Coefficient at 91 days Miami Oolite limestone Georgia granite Figure 7-25 Relationship between cree p coefficient at 91 days and fc/E Table 7-3 Regression analysis on relationship of elastic modulus to creep coefficient using Equation 7-3 95% confidence interval 95% confidence interval R2 SSE -4.55E-07 -5.67E-07 ~ -3.43E-07 3.725 3.151 ~ 4.299 0.6671 0.1742 Table 7-4 Regression analysis on re lation of creep coefficient to fc/E using Equation 7-4 95% confidence interval 95% confidence interval R2 SSE -1132 -1609 ~ -1014 3.485 3.010 ~ 3.959 0.7026 0.1647 7.3.6 Effects of Coarse Aggre gate Type on Creep Coefficient As can be seen from Figure 7-26, the creep co efficients of concretes made with Georgia granite is higher than those of concretes with Miami Oolite limestone aggregate. This is due probably to the lower elastic deformation of concretes with Georgia granite aggregate in comparison with those with Miami Oolite limestone aggregate. Therefore, the ratio of creep

PAGE 171

172 strain to elastic strain is larger for Georgia granite aggregate concrete However, lightweight aggregate concrete behaves in a different way in comparison with Georgia granite aggregate concrete. Since the elastic deformation of lightwei ght aggregate concrete is significantly higher than that of Georgia granite aggregate concrete and Miami Oolite limestone aggregate concrete, the ratio of creep strain to elastic strain is lower for lightweight aggregate concrete. This observation is in agreement with the conclusion given by Neville [A.M. Neville, 1996]. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 Mix-2Mix-3Mix-5Mix-7 MixtureCreep Coefficient at 91 days Miami Oolite limestone Georgia granite Figure 7-26 Effects of coarse aggregate type on creep coefficient at 91 days 7.4 Creep Modulus Creep modulus, defined as the ratio of stress applied to concrete specimen to the total strain excluding shrinkage strain, reflects the decay of stiffness with time. Apparently, this parameter is of great important in inelastic stru ctural material analysis to obtain time-dependent elastic modulus so that accurate deformation of material can be computed correctly using the

PAGE 172

173 reduced elastic modulus. Figure 7-27 presents a typical decay curve of concrete mixture investigated in this study. As can be seen from Table 7-1, for the fl y ash concrete mixtures, curing condition has significant effects on the creep modulus as a function of time. That is to sa y, the decay of creep modulus of specimen moist-cured fo r 14 days is considerably less th an that of the same concrete moist-cured for 7 days. The same observation can also be made on the lightweight aggregate concrete as well. This indicates that curing cond ition plays a very significant role in decreasing creep strain of fly ash concrete and lightweight aggregate concrete. However, for the slag concrete mixtures, no appreciable effects of curing condition on creep modulus can be observed. This means that a longer curing time beyond 14 days has no significant influence on the creep behavior of slag concrete. 0.00E+00 1.00E+06 2.00E+06 3.00E+06 4.00E+06 5.00E+06 6.00E+06 0102030405060708090100 Time (days)Creep Modulus (psi) 7-day moist curing-40% of compressive strength 7-day moist curing-50% of compressive strength 14-day moist curing-40% of compressive strength 14-day moist curing-50% of compressive strength Figure 7-27 Typical decay curves of creep modulus with time

PAGE 173

174 7.5 Prediction of Ultimate Creep Strain It is often assumed that creep rate for a c oncrete material decreases with time, and the creep strain will approach a lim iting value after an infinite ti me under load. The study by G.E. Troxell et al [G.E.Troxell et al, 1958] indicates that th e average value of cr eep strain after 30 years is 1.36 times the one-year creep strain. In engineering practical point of view, it is often assumed that the 30-year creep strain represents the ultimate creep stain. The ultimate creep strain of concrete invest igated in this study was determined using asymptotic equation, given as follows to fit the experimental data. t tc (7-5) This equation is the ratio of two polynomials. As the time variable approaches infinity, the ratio of two polynomials will be equal to 1. Th erefore, ultimate creep strain is equal to In this equation, and are two parameters to be determined from curve-fitting, and which is the factor borrowed fr om CEB-FIP Equation, reflects the effect of geometrical characteristics of specimen and relative humidity on creep behavior of concrete. The relative humidity was controlled at 75% in this study. "12"6 cylindrical specimens were used for creep tests. The geometric characteris tic of the test specimen, h, can be computed as follows: mm in u A hc2.763 6 32 22 (7-6) Then, can be obtained as follows: 15005.381250 100%100 %75 2.1115018 h (7-7) Thus, the equation used to fit the experimental data becomes

PAGE 174

175 5.381 t tc (7-8) Least Squares Method of curve fitting as described in Chapter 6 was used to determine two unknown parameters, and Ultimate creep strains and ultimate creep coefficient after regression analysis for 14 concrete mi xtures are presented in Table 7-5. Table 7-5 The predicted ultimate creep strain and creep coefficient Predicted items Ultimate creep strain ultimate creep coefficient Curing conditions curing condition 1 Curing c ondition 2 curing condition 1 Curing condition 2 Loading conditions 40% 50% 40% 50% 40% 50% 40% 50% Mix-1F 1.06E-03 1.30E-03 0.88E-03 1.03E-03 1.48 1.55 1.14 1.16 Mix-2F 1.93E-03 2.08E-03 1.66E-03 2.11E-03 2.91 2.59 2.37 2.44 Mix-3F 1.45E-03 1.86E-03 1.39E-03 1.56E-03 2.30 2.40 2.11 1.90 Mix-4F 1.37E-03 1.59E-03 1.24E-03 1.63E-03 2.28 2.14 2.14 2.32 Mix-5S 1.40E-03 1.84E-03 1.25E-03 1.64E-03 2.10 2.17 1.74 1.84 Mix-6S 1.68E-03 1.87E-03 1.55E-03 1.75E-03 2.51 2.23 2.23 2.05 Mix-7S 1.41E-03 1.69E-03 1.46E-03 1.60E-03 2.71 2.71 2.61 2.46 Mix-8S 1.58E-03 1.97E-03 1.45E-03 1.95E-03 2.57 2.72 2.21 2.34 Mix-9LF 1.11E-03 1.40E-03 0.99E-03 1.16E-03 1.78 1.83 1.46 1.49 Mix-10LS 0.94E-03 1.19E-03 0.76E-03 0.97E-03 1.61 1.45 1.32 1.26 Mix-2GF ----1.80E-03 2.10E-03 ----2.99 2.70 Mix-3GF ----1.57E-03 1.81E-03 ----2.96 2.72 Mix-5GS ----1.42E-03 1.77E-03 ----2.51 2.55 Mix-7GS ----1.49E-03 1.76E-03 ----2.89 2.69 As shown in Table 7-6, it is to be pointed out that most of the concretes investigated in this study have an ultimate creep coefficient higher than 2.0. 7.6 Evaluation on Creep Prediction Models The effectiveness of other creep prediction models, such as Burgers model, C.E.B-F.I.P model and ACI 209 model, were evaluated in this study. Burgers model Burgers Model or four-element model, as show n in Figure 7-28, was also used to fit the experimental data to evaluate the feasibility of the Burgers model to predict creep strain of concrete at a later time, based on the expe rimental data obtain ed in three months.

PAGE 175

176 Figure 7-28 Burgers Model The total strain predicted by the Burgers model can be considered as the sum of the strain responses of each element under the applied lo ad, and can be expressed by the following equation: 321 (7-9) Where 1 is the elastic strain of spring in a Maxwell model, and it can be given as 1 1R (7-10) 2 is viscous flow of dash-pot in a Maxwell model, and its rate type formul a can be expressed as 1 2' (7-11) 3 is the strain of a Kelvin unit, and it can be related to the applied stress as 2 3 2 2 3' R (7-12) Eliminating 1, 2, and 3 from the above four equations, the constitutive relationship between and in the Burgers model can be expressed as R1 1 R2 2 1 2 3 0 t 1 t 0 B A` 3 C A 2 1 D O

PAGE 176

177 "'"'2 21 1 21 21 2 2 2 1 1 1 R RRRRR (7-13) Solving the above second order differentia l equation with init ial conditions of 2 0 1 0 32 1 0 1' 0 0 R t (7-14) The creep behavior of Burgers model under the constant stress can be derived as: t R R t R t2 2 2 0 1 0 1 0exp1 (7-15) In this study, only creep strain was considered. Thus, we can eliminate the first term in Equation 7-9. Therefore, the strain in the Burgers model becomes: t R R tt2 2 2 0 1 0exp1 (7-16) Three material constants, R2, 1 and 2, can be easily determined by curve-fitting Equation 7-16 to the experimental data. As can be seen from Equation 7-16, after a ce rtain time, the second term on right side of equation will decay and approaches 2 0R and the creep rate will become a constant value, i.e. 1 0 So, after a long time, the expression for the strain from the Burgers model can be simplified as follows: 2 0 1 0R tt (7-17)

PAGE 177

178 Burgers model with constitutive parameters determined from regression analysis was plotted in Figure 7-29. As can be seen from Figure 7-29, Burgers model is very capable to simulate the development trend of creep of concrete. However, it indicates that the extrapolation made by Burgers model results in overestimation of the ultimate creep strain. This is due the lack of long-term creep data from this study. It is not possible to dete rmine the constitutive parameters accurately without long-term creep data. 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 020406080100 Time (days)Creep Strain 14-day-40% 14-day-50% Regression analysis Burger's Model Figure 7-29 Prediction of strain using the Burgers model C.E.B-F.I.P Model (1990) C.E.B-F.I.P Model is an empirical model re commended by Europe Union in 1990. In this model, the creep strain can be predicted based on the information from ultimate compressive strength and modulus of elastic ity at loading age, and a time function determined according to the mechanical properties of specific concrete mixture, the geometry of specimen, and the curing conditions applied to the specimen, and so on. The general equation is given as follows:

PAGE 178

179 ),( )( ),(0 0 0tt E t ttci ci c cr (7-18) For the detail description about C.E.B-F.I.P mode l, please refer to the literature review in Chapter 2. Finally, combining all the equations together and simplifying them, we have the following equation used to predict the development of creep strain with time. 3.0 10 10 2.0 10 3/1 0 0 0 0/)( /)( )/(1.0 1 / 3.5 )/(46.0 /1 1 )( ),( ttt ttt tt ff hh RHRH E t ttH cmo cm ci c cr (7-19) In this study, the relative humidity is controlled at 75%. For "12"6 cylinder, the geometrical characteristic of the test sp ecimen, h, can be computed as follows: mm in u A hc2.763 6 32 22 (7-20) Then,h can be obtained as follows: 15005.381250 100 2.76 %100 %75 2.1115018 H (7-21) Then, the prediction formula can be simplified as follows: For concrete cured for 14 days: 3.0 14 0 0)14(5.381 )14(55.18 )( ),( t t f E t ttcm c c cr (7-22) The above equation is an asymptotic function. As time approaches infinity, creep strain will reach ultimate creep strain cm ci cf E t 55.18 )(0. Similarly, for the concrete specimen cured for 28 days, the prediction equation becomes

PAGE 179

180 3.0 28 0 0)28(5.381 )28(55.18 )( ),( t t f E t ttcm c c cr (7-23) As can be seen from the above equation, this asymptotic equation approaches a limiting value as time approaches infinity. Therefore, u ltimate creep strain can be computed by the following formula: cm c c ultf E t 55.18 )(28 0 (7-24) To evaluate the effectiveness of the C.E. B-F.I.P model, the C.E.B-F.I.P Equation was plotted in Figure 7-30. It indica tes that C.E.B-F.I.P model gives very good prediction. To verify this conclusion, the creep strain at 91 days from experimental measurem ents is plotted against the creep strain computed according to C.E.B-F.I. P model in Figure 7-31. It clearly shows that the measurements match very well with the predictions made by the C.E.B-F.I.P model. 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 0102030405060708090100 Time (days)Creep Strain 14-day-40% 14-day-50% Regression analysis CEB-FIP model ACI 209 model Figure 7-30 Comparison on the effectiveness of C.E.B-F.I.P model and ACI model

PAGE 180

181 y = x 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 1.80E-03 0.00E+003.00E-046.00E-049.00E -041.20E-031.50E-031.80E-03 Predicted Creep Strain at 91 daysCreep Strain at 91 days First phase Second Phase Figure 7-31 Comparison between the creep strain at 91 days from experimental data and the predicted creep strain using CEB-FIP model Also, in order to verify if there is simple linear relationship between creep strain and cmfE the creep strain at 91 days was plotted against cmfE in Figure 7-31, where is stress applied to the specimen ; E is elastic modulus of concrete at loading age; and fcm is characteristic strength of concrete at loadi ng age. Then, a linear regression analysis was performed to determine the relationship between creep strain at 91 days and cmfE and the analyzed results are shown in Table 7-6. As can be seen from Figure 7-31, creep strain at 91 days is linearly related to cmfE The regression equation is given as follows: 4 9110758.1 40.13 cm cfE (7-25)

PAGE 181

182 Table 7-6 Regression analysis on re lation of creep coefficient to cmfE 95% confidence interval 95% confidence interval R2 SSE 13.40 11.21 ~ 15.58 -1.758E-04 -3.649E-04 ~ -1.333E-04 0.6848 1.193E-04 In addition, the ultimate creep strains predicted by curve-fitti ng to experimental data were plotted against the creep strains ca lculated using the original C.E.BF.I.P model in Figure 7-32. It indicates that original C.E.B-F.I.P model gives very good creep strain prediction for the normalweight concrete mixtures i nvestigated in this study. 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 1.80E-03 0.00E+003.00E-056.00E-059.00E-051.20E-041.50E-04 c/(E fcm^0.5)Creep Strain at 91 days Figure 7-32 Relationship between creep strain and mechanical properties at loading age

PAGE 182

183 y = x 0.00E+00 5.00E-04 1.00E-03 1.50E-03 2.00E-03 2.50E-03 3.00E-03 0.00E+005.00E-041.00E-031.50E-032.00E-032.50E-033.00E-03 Predicted Ultimate Creep Strain by CEB-FIP modelUltimate Creep Strain by Curve-fitting Second phase First phase Figure 7-33 Comparison between the ultimate creep strain calculated by C.E.B-F.I.P model and that by curve-fitting ACI-209R model The evaluation on ACI 209 model was performed in this study. ACI 209 (1992) model is given as follows: 6.0 0 6.0 0 0 028)(10 )( )(),( tt tt ttt (7-26) Where ),(028tt Creep coefficient at time t; )(0t Ultimate creep coefficient; 0t Time of loading. In this study, 140 t days for concrete cured for 14 days before loading; and 280 t days for concrete cured for 28 days before loading. The ultimate creep coefficient can be expressed as: ct )(0 (7-27)

PAGE 183

184 The constant 35.2 is recommended. The correction factors c consist of the following terms: a satRHlac (7-28) Where la Correction factor for loading age, which is equal to 0.916 for specimen cured for 14 days, and 0.814 for specimen cured for 28 days. RH Correction factor for ambient relative humidity. In this study, the ambient relative humidity is 75%, then77.0RH s Correction factor for slump of fresh concrete. l sS 00264.082.0 (lS is slump in mm). Correction factor for fine to total aggregate ratio. a 0024.088. 0 (a is fine to total aggregate ratio) a Correction factor for air content. a aa 09.046.0 (aa is air content) at Correction factor for thickness of member In this study, the volume-surface ratio method is used to obtain at )(0213.013.11 3 2s v ate (7-29) Where s v = Volume to surface ratio in mm. The correction factors based on the concrete mixtures, geometry of specimen and ambient conditions employed in this study for the ACI 209 model are provided in Table 7-7.

PAGE 184

185 Table 7-7 Correction factors for the ACI 209 model la c Mix 7-day moist 14-day moist rh s a at p 7-day moist 14-day moist Mix-1F 0.916 0.814 0.77 1.34 0.57 1.00 0.88 0.30 0.27 Mix-2F 0.916 0.814 0.77 1.32 0.87 1.00 0.88 0.45 0.40 Mix-3F 0.916 0.814 0.77 0.92 0.69 1.00 0.88 0.36 0.32 Mix-4F 0.916 0.814 0.77 1.02 0.64 1.00 0.88 0.33 0.29 Mix-5S 0.916 0.814 0.77 1.31 0.80 1.00 0.88 0.42 0.37 Mix-6S 0.916 0.814 0.77 1.05 0.66 1.00 0.88 0.34 0.30 Mix-7S 0.916 0.814 0.77 1.09 0.96 1.00 0.88 0.50 0.44 Mix-8S 0.916 0.814 0.77 1.00 0.80 1.00 0.88 0.41 0.37 Mix-9LF 0.916 0.814 0.77 0.82 0.73 1.00 0.88 0.38 0.33 Mix-10LS 0.916 0.814 0.77 0.82 0.93 1.00 0.88 0.48 0.43 Mix-2GF 0.916 0.814 0.77 1.12 1.13 1.00 0.88 0.58 0.52 Mix-3GF 0.916 0.814 0.77 0.99 0.60 1.00 0.88 0.31 0.27 Mix-5GS 0.916 0.814 0.77 1.26 0.96 1.00 0.88 0.50 0.44 Mix-7GS 0.916 0.814 0.77 0.97 0.80 1.00 0.88 0.41 0.37 As can be seen from Figure 7-34, ACI 209 model greatly underestimates the creep strain of the concretes investigated in this study. y = x 0.00E+00 3.00E-04 6.00E-04 9.00E-04 1.20E-03 1.50E-03 1.80E-03 0.00E+003.00E-046.00E-049.00E-041.20E-031.50E-031.80E-03 Calculated Creep strain at 91 daysCreep Strain at 91 days from Experiment ACI-209 C.E.B-F.I.P Figure 7-34 Evaluation on ACI-209 model and C.E.B-F.I.P model

PAGE 185

186 7.7 Summary of Findings This chapter presents the results from the creep tests in this study. The following is a summary of m ajor findings from the creep tests: (1) Curing condition has some effect on creep of fly ash concrete and lightweight aggregate concrete, while its effect is very slight on slag concrete. (2) For the stress levels used (40 and 50% of compressive st rength), the measured creep strain and instantaneous strain were linearly proportional to the stress applied. Thus, the computed creep coefficients were not aff ected by the stress le vel in this study. (3) Water to cementitious materials ratio has some effects on creep behavior of concrete. The higher the water to cementitious materials ratio, the more the concrete creeps. (4) For the concrete with identical water to cem entitious materials ratio, the higher the air content of fresh concrete, the more the concrete creeps. (5) The concretes with granite aggregate creeps sl ightly more than the concretes with Miami Oolite limestone aggregate and lightweight aggregate under the same stress level. However, due to the much lower elastic modul us of lightweight a ggregate concrete, the creep coefficient of lightweight aggregate co ncrete is much lower than that of normal weight aggregate concrete. Due to the hi gher elastic modulus of granite aggregate concrete, creep coefficient of granite concrete was much higher than that of the concretes with Miami Oolite limestone aggregate. (6) A simple linear relationship was established between compressive strength at loading age and creep strain at 91 days. (7) A linear relationship was also found betw een creep coefficient at 91 days and compressive strength (' cf ), elastic modulus (cE ), and the ratio of compressive strength and elastic modulus. The regre ssion equation related compressive strength at loading age to creep coefficient at 91 days (91 c ) is given as follows: 91 c cf (7-2) Where is equal to -2.03 10-4 and equal to 3.042; cf is in unit of psi. The regression equation relating el astic modulus to creep coefficient at 91 days is given as follows: c cE91 (7-3) Where is equal to -4.55 10-7 and equal to 3.725; cE is in unit of psi.

PAGE 186

187 The equation related creep coefficient at 91 da ys to the ratio of co mpressive strength to elastic modulus is given as follows: c c cE f' 91 (7-4) With equal to -1132 and equal to 3.485. Among these regression equations, E quation 7-2 gave the best prediction. (8) Ultimate creep coefficient of some of the concretes appeared to exceed 2.0. These concrete mixtures included Mix-2F, Mix-3F, Mix-4F, Mix5S, Mix-6S, Mix-7S, Mix-8S, Mix-2GF, Mix-3GF, Mi x-5GS and Mix-7GS. (9) CEB-FIP model (as shown in Equation 7-17) ap peared to give better prediction on the creep behaviors of concretes investigated in this study than ACI 209 model (as shown in Equation7-25).

PAGE 187

188 CHAPTER 8 CONCLUSIONS AND RECOMMENDATIONS 8.1 Design of Creep Apparatus Perform ance and characteristics of creep appara tus designed for this st udy are presented as follows: 1) The creep apparatus designed in this study is capable of applying and maintaining a load up to 145,000lbs on the test specimens w ith an error of less than 2%. 2) Three specimens can be stacked for simultaneous loading. 3) When a maximum load of 145,000lbs is applied, the deflection of bearing surfaces of the header plates is less than 0.001in, and th e pressure distributio n on the test specimen varies by less than 0.026%, or 1.5psi. 4) The creep testing procedures developed in this study was foun d to work very well. They are given in detail in Section 4.3. 8.2 Findings from This Study 8.2.1 Strength and Elastic Modulus 1) Splitting tensile strengths of the concre te m ixtures using granite aggregate were significantly lower than thos e using Miami Oolite limestone aggregate. This is due probably to the poor bonding condition betw een hardened cement paste and granite aggregate. 2) Compressive strengths of c oncretes with granite aggregate were comparable to or lower than those of concretes with Miami Oolite limestone aggregate. 3) The concrete with granite aggregate had hi gher elastic modulus than that with Miami Oolite limestone aggregate, while the lightweight aggregate concretes had lower elastic modulus than the normal weight concretes. 4) Fly ash concretes develop compressive strength and splitting tensile st rength at a slower rate than the slag concretes. Fly ash conc rete shows significant strength gain after 28 days, while this was not seen fr om the slag concrete mixtures. 5) The ACI 209 Equation for prediction of compressive strength () ('tfc) at various curing age from compressive strength at 28 days ( )(' 28tfc), which is given as follows, was modified to give better strength prediction fo r the various mixtures.

PAGE 188

189 28 85.00.4 )( c f t t t c f The modified equation has the following form for the concrete with different coarse aggregates: 28 )( c f t t t c f The value of was found to vary from 1.1 to 2.6 for the concretes with Miami Oolite limestone aggregate, from 2.6 to 5.3 for th e concretes with Georgia granite aggregate, and from 4.2 to 6.7 for lightweight aggregate concretes; the value of was found to vary from 0.82 to 0.93 for the concretes with Miam i Oolite limestone aggregate, from 0.82 to 0.89 for the concrete with Georgia granite aggregate, and from 0.74 to 0.82 for lightweight aggregate co ncrete in this study. 6) The relationship between compressive strength (' cf ) and splitting tensile strength (ctf ) is established for the concrete mixtures investigated in this study. The Carino and Lew model, given as follows, 73.0 c f ct f was modified to the following equation: 7185.0 c f ct f Where cf and ctf are in units of psi. 7) The relationship between compressive strength and modulus of elasticity was refined in this study using Least Square of Curvefitting Technique. The ACI 318-89 Equation, which is '57000cf c E was modified to the following equation: cf c E Where is equal to 55,949 for Miami Oolite lim estone aggregate; 62,721 for Georgia granite aggregate; and 43,777 for Stalite lightweight aggregate. cf and cE are in units of psi. 8) For all three aggregate t ypes investigated in this study, a modified ACI 318-95 prediction equation was developed: 484200 16.30'5.1cfw E Where w is the density of c oncrete in pound per cubit foot. cf and cE are in units of psi.

PAGE 189

190 8.2.2 Shrinkage Characteristic s of Concretes I nvestigated 1) Fly ash concrete mixtures had slightly hi gher shrinkage strain at 91 days than slag concretes. This is due probably to the slow hydration rate of fly ash in comparison with that of slag. As a result of slower rate of hydration, there is more free water evaporating from the interior of the concrete, which can cause the concrete to shrink more. Thus, it is recommended that using a longer wet curing time would be helpful to reduce shrinkage of fly ash concrete. 2) Water content has a significant effect on dryi ng shrinkage strain of concrete. The higher the water content, the more the concrete tends to shrink. However, no clear trend can be seen on the effects of water to cementitious materials ratio on shrinkage of concrete. 3) For the four concrete mixtures with Georgia granite aggregate, shrinkage strain is slightly lower than the four corresponding concrete mixtures with Miami Oolite limestone aggregate. Lightweight aggregate concrete shrinks more than normal weight aggregate concrete. This might be explained by their difference in elastic modulus. The concrete with a higher elastic modulus would have a st ronger resistance to the movement caused by shrinkage of cement paste. 4) For the concretes tested, there appeared to be a relations hip between the compressive strength (' cf ) at the age when shrinkage test wa s started and the shrinkage strain (sh ) at 91 days as follows: '0001.0 0005.0cf e sh Where cf is in unit of psi. 5) For the concretes tested, ther e appeared to be a relations hip between elastic modulus (cE ) at the age when shrinkage test was started and the shrinkage strain (sh ) at 91 days as follows: c shE e 7102 0007.0 Where cE is in unit of psi. 6) According to the shrinkage test results from this study, the C.E.B-F.I.P model (as shown in Equation 6-6) appeared to give better prediction than the ACI 209 model (as shown in Equation 6-3). Using ACI 209 model may resu lt in over-estimation of the ultimate shrinkage strain. 7) For the concrete investigated in this study, the ultimate shrinkage strain ranged from 1.9310-4 to 3.64 10-4 for the concretes with Miami Oolite limestone aggregate; from 2.1810-4 to 2.83 10-4 for the concretes with Georgia granite aggregate; and from 3.4910-4 to 4.22 10-4 for the concretes with Stalite lightweight aggregate concrete.

PAGE 190

191 8.2.3 Creep Characteristics of Concretes Investigated 1) Curing condition has som e effects on creep of fly ash concrete and lightweight aggregate concrete, while its effect on slag concrete is very small. 2) For the stress levels used (40 and 50% of compressive strength) the measured creep strain and instantaneous strain were linearly proportional to the stress applied. Thus, the computed creep coefficients were not aff ected by the stress le vel in this study. 3) Water to cementitious materials ratio has some effects on creep behavior of concrete. The higher the water to cementitious materials ratio, the more the concrete creeps. 4) For the concrete with identical water to cem entitious materials ratio, the higher the air content of fresh concrete, the more the concrete creeps. 5) The concretes with granite aggregate creeps slightly higher than the concretes with Miami Oolite limestone aggregate and lightweig ht aggregate under the same stress level. However, due to the much lower elastic modul us of lightweight a ggregate concrete, the creep coefficient of lightweight aggregate co ncrete is much lower than that of normal weight aggregate concrete. Due to the hi gher elastic modulus of granite aggregate concrete, creep coefficient of granite concrete was much higher than that of the concretes with Miami Oolite limestone aggregate. 6) A simple linear relationship was established between compressive strength at loading age and creep strain at 91 days. 7) A linear relationship was also found betw een creep coefficient at 91 days and compressive strength (' cf ), elastic modulus (cE ), and the ratio of compressive strength and elastic modulus. The regression equation, which relates compressive strength at loading age to creep coefficient at 91 days (91 c ) is given as follows: 91 c cf (7-2) Where is equal to -2.03 10-4 and equal to 3.042. And' cf is in unit of psi. The regression equation, which relates elastic modulus to creep coefficient at 91 days is given as follows: c cE91 (7-3) Where is equal to -4.55 10-7 and equal to 3.725. And cE is in unit of psi. The equation related creep coefficient at 91 da ys to the ratio of co mpressive strength to elastic modulus is given as follows:

PAGE 191

192 c c cE f' 91 (7-4) With equal to -1132 and equal to 3.485. Among these regression equations, Equati on 7-2 gave the best prediction. 8) Ultimate creep coefficient of some of the concretes appeared to exceed 2.0. These concrete mixtures included Mix-2F, Mix-3F, Mix-4F, Mix5S, Mix-6S, Mix-7S, Mix-8S, Mix-2GF, Mix-3GF, Mi x-5GS and Mix-7GS. 9) CEB-FIP model (as shown in Equation 7-17) ap peared to give better prediction on the creep behaviors of concretes investigated in this study than ACI 209 model (as shown in Equation7-25). 8.3 Recommendations Based on this study, the f ollowing recomme ndations are given for the further study: 1) Study on effects of aggregate gradation on sh rinkage and creep of concrete. Since the gradation of aggregate has a great effect on the compressive st rength of concrete [A.M.Neville, 1996] [Larry C. Muszynski et al, 1997] and compressive strength was found to be related to shrinkage and creep in this study, the effects of aggregate gradation on shrinkage and creep behavior of concrete should be studie d in order to have a better understanding of this factor on sh rinkage and creep of concrete. 2) Study on the optimization of mix proportion. The optimization of mix proportion should be studied to reduce shrinka ge and creep of concrete. 3) Study on the interfacial characte ristics between coarse aggr egate and mortar paste in order to have a better interpretation on the e ffects of different aggr egate types on strength of concrete. 4) Study on rheological properties of concrete unde r sustained load in order to have a better understanding about the creep behavior of concrete.

PAGE 192

193 APPENDIX A MEASUREMENTS FROM STRENGTH TESTS

PAGE 193

194Table A-1 Results of compre ssive strength tests (psi) Age of Testing (days) 3 7 14 28 56 91 No. of mix 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1F 8018 8091 8123 8556 8554 8607 8929 8869 9182 9319 9811 9479 10665 10799 10847 11123 11302 11376 2F 4110 4195 3927 4660 4680 4635 6053 6032 5999 6499 6268 6752 6661 6604 6648 7631 7582 7609 3F 5325 5424 5118 6448 6449 6512 7475 7649 7578 8229 8147 8349 8479 8400 8468 9415 9496 9366 4F 5669 5783 5684 7075 6762 6922 7224 7208 6910 7038 7509 7160 8668 8994 9325 9273 9072 9467 5S 5351 5772 5539 7059 7739 6908 7995 8208 8541 8684 8924 8888 9071 9255 9092 9348 9615 9406 6S 6300 6402 6423 7776 7316 8004 8211 8481 8169 8684 9127 9223 9604 9540 9593 9779 9734 9770 7S 4323 4482 4166 5311 5435 5375 5993 5902 5886 6346 6441 6389 6773 6812 6798 6990 6837 6923 8S 4415 5017 4954 5831 6202 6308 6879 6967 6971 7544 7282 7749 7856 8253 8249 8262 8148 8214 9LF 3019 3007 3092 3911 3939 3974 5039 5174 5194 5981 5999 5806 6655 6953 6462 7043 7092 6750 10LS 1486 1411 1504 2175 2310 2088 2749 2860 3201 3760 3811 3660 4496 4204 4236 4863 4725 4595 2GF 3982 3867 3807 4922 5046 4888 5874 5812 5735 6440 6388 6579 6887 7001 6969 7387 6909 7308 3GF 2960 2865 3099 4810 4612 4655 5468 5778 5829 6816 7075 7134 7818 7801 7943 7862 7915 8105 5GF 3746 3861 3847 5098 5211 5145 6196 6087 6127 7000 7409 7377 7895 7683 7769 8047 8090 7986 7GF 2249 2205 2346 4433 4178 4298 5308 5182 5175 6601 6603 6632 7072 6629 7176 7226 7200 7273

PAGE 194

195Table A-2 Normalized compressive streng th development characteristics of th e concrete mixtures evaluated (psi) Age of Testing (days) Mix Number W/C Fly ash Slag 3 7 14 28 56 91 Mix-1F 0.24 20% 0.72 0.76 0.80 0.85/0.93* 0.96 1 Mix-2F 0.33 20% 0.54 0.61 0.79 0.86/0.87* 0.90 1 Mix-3F 0.41 20% 0.56 0.69 0.80 0.87/0.85* 0.90 1 Mix-4F 0.37 20% 0.62 0.75 0.77 0.78/0.87* 0.97 1 Mix-5S 0.33 50% 0.59 0.77 0.87 0.93/0.99* 0.97 1 Mix-6S 0.36 50% 0.66 0.80 0.89 0.94/0.95* 0.99 1 Mix-7S 0.41 70% 0.63 0.78 0.86 0.92/0.93* 0.98 1 Mix-8S 0.44 50% 0.58 0.74 0.85 0.92/0.92* 0.99 1 Mix-9LF 0.31 20% 0.44 0.57 0.74 0.85/0.84* 0.96 1 Mix-10LS 0.39 60% 0.31 0.46 0.62 0.79/0.85* 0.91 1 Mix-2GF 0.33 20% 0.54 0.69 0.81 0.90 0.97 1 Mix-3GF 0.41 20% 0.47 0.64 0.76 0.90 0.97 1 Mix-5GS 0.33 50% 0.37 0.58 0.70 0.86 0.97 1 Mix-7GS 0.41 70% 0.31 0.59 0.72 0.91 0.93 1 Note: Data from the replication tests.

PAGE 195

196Table A-3 Results of splitting tensile strength tests (psi) Age of Testing (days) 3 7 14 28 56 91 No. of Mix 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1F 621 573 582 657 613 614 673 768 706 823 794 770 833 826 844 863 834 851 2F 397 428 401 501 484 468 551 521 515 545 542 539 650 596 617 675 645 658 3F 503 527 510 550 502 568 579 541 567 644 620 608 678 673 671 740 722 731 4F 480 434 459 604 440 517 581 455 663 678 684 647 776 737 764 796 748 766 5S 492 429 405 567 557 599 724 507 677 757 615 697 716 704 713 748 772 695 6S 607 523 580 633 586 589 616 755 575 696 658 663 711 654 707 728 708 719 7S 430 415 434 467 476 475 553 509 493 567 604 473 489 657 625 572 602 616 8S 324 383 409 428 512 557 555 530 564 617 603 681 702 691 686 696 709 704 9LF 283 369 399 425 350 438 470 460 416 472 486 512 563 549 542 579 601 552 10LS 211 203 222 316 295 253 366 351 376 413 404 400 433 401 420 444 433 414 2GF 350 340 366 425 429 408 518 446 502 541 557 535 557 550 539 585 606 595 3GF 283 288 276 433 411 417 442 522 422 521 508 547 516 646 611 617 646 684 5GS 364 410 372 381 391 456 507 509 494 563 564 553 621 600 578 652 642 659 7GS 234 258 245 363 353 371 411 418 460 540 582 515 566 623 607 555 584 593

PAGE 196

197Table A-4 Normalized Splitting tensile st rength development characteristics of the concrete mixtures evaluated (psi) Age of Testing (days) Mix Number W/C Fly ash Slag 3 7 14 28 56 91 Mix-1F 0.24 20% 0.70 0.74 0.84 0.94/0.86* 0.98 1.00 Mix-2F 0.33 20% 0.62 0.73 0.80 0.82/0.87* 0.94 1.00 Mix-3F 0.41 20% 0.70 0.74 0.77 0.850.83* 0.92 1.00 Mix-4F 0.37 20% 0.59 0.68 0.74 0.87/0.80* 0.99 1.00 Mix-5S 0.33 50% 0.60 0.78 0.86 0.93/0.92* 0.96 1.00 Mix-6S 0.36 50% 0.79 0.84 0.90 0.94/0.87* 0.96 1.00 Mix-7S 0.41 70% 0.71 0.79 0.87 0.92/0.87* 0.99 1.00 Mix-8S 0.44 50% 0.53 0.71 0.78 0.90/0.93* 0.99 1.00 Mix-9LF 0.31 20% 0.61 0.70 0.78 0.85/0.88* 0.95 1.00 Mix-10LS 0.39 60% 0.49 0.67 0.85 0.94/0.82* 0.97 1.00 Mix-2GF 0.33 20% 0.59 0.71 0.82 0.89 0.92 1.00 Mix-3GF 0.41 20% 0.59 0.63 0.77 0.86 0.92 1.00 Mix-5GS 0.33 50% 0.43 0.65 0.71 0.81 0.91 1.00 Mix-7GS 0.41 70% 0.42 0.63 0.75 0.87 0.96 1.00 Note: Data from the replication tests

PAGE 197

198Table A-5 Results of elastic modulus tests ( 106psi) Age of Testing (days) 3 7 14 28 56 91 No. of Mix 1 2 1 2 1 2 1 2 1 2 1 2 1F 4.71 4.77 4.92 4.94 5.20 5.25 5.37 5.43 5.56 5.52 5.57 5.59 2F 3.47 3.38 3.72 3.82 4.11 4.04 4.28 4.34 4.46 4.40 4.77 4.50 3F 4.37 4.42 4.87 4.83 5.02 5.07 5.08 5.19 5.38 5.18 5.66 5.73 4F 4.50 4.47 4.63 4.59 4.85 4.90 4.98 5.03 5.16 5.14 5.33 5.25 5S 4.11 4.11 4.53 4.78 4.86 4.89 5.06 5.12 5.19 5.26 5.23 5.22 6S 4.42 4.11 4.97 4.86 5.08 5.28 5.23 5.67 5.48 5.75 5.54 5.78 7S 3.99 3.80 4.30 4.30 4.53 4.51 4.59 4.61 4.75 4.71 4.78 4.74 8S 3.87 4.04 4.43 4.35 4.90 4.78 5.02 4.98 5.14 5.12 5.16 5.15 9LF 2.71 2.81 2.94 2.90 3.16 3.10 3.29 3.25 3.34 3.36 3.69 3.31 10LS 1.77 1.73 2.01 1.74 2.40 2.32 2.73 2.65 3.07 2.94 2.98 3.09 3GF 3.61 3.99 4.10 4.33 4.59 4.63 4.85 5.07 5.17 5.06 5.25 5.12 4GF 4.08 4.21 4.28 4.95 5.56 5.48 5.62 5.59 5.83 6.03 5.95 5.97 5GS 3.24 3.06 3.66 3.97 4.54 4.76 5.42 4.92 5.48 5.26 5.47 5.64 7GS 2.63 2.74 3.28 3.48 4.05 4.14 5.17 5.33 5.64 5.56 5.77 5.68

PAGE 198

199 APPENDIX B MEASURED AND CALCULATED RESULTS FROM CREEP TESTS

PAGE 199

200Table B-1 Measured and calcula ted results from creep tests Age of testing (days) No. of Mix Curing condition Load level Strain 3 7 14 28 56 91 Total 0.001160 0.001240 0.001330 0.001460 0.001600 0.001700 Shrinkage 0.000021 0.000043 0.000076 0.000120 0.000160 0.000200 Elastic 0.000716 0.000716 0.000716 0.000716 0.000716 0.000716 Creep 0.000430 0.000480 0.000540 0.000620 0.000720 0.000780 Creep coefficient 0.60 0.68 0.76 0.87 1.00 1.10 40% Creep modulus 3.44E+06 3.16E+06 3.07E+06 2.88E+06 2.65E+06 2.52E+06 Total 0.001310 0.001420 0.001520 0.001660 0.001840 0.001970 Shrinkage 0.000021 0.000043 0.000076 0.000120 0.000160 0.000200 Elastic 0.000804 0.000804 0.000804 0.000804 0.000804 0.000804 Creep 0.000450 0.000530 0.000610 0.000700 0.000840 0.000930 Creep coefficient 0.54 0.64 0.72 0.84 1.00 1.13 7-day moist cure 50% Creep modulus 3.32E+06 3.24E+06 3.02E+06 2.84E+06 2.65E+06 2.52E+06 Total 0.001070 0.001150 0.001230 0.001340 0.001450 0.001550 Shrinkage 0.000014 0.000033 0.000063 0.000100 0.000140 0.000170 Elastic 0.000760 0.000760 0.000760 0.000760 0.000760 0.000760 Creep 0.000290 0.000350 0.000400 0.000470 0.000550 0.000620 Creep coefficient 0.38 0.46 0.53 0.62 0.72 0.81 40% Creep modulus 3.78E+06 3.58E+06 3.44E+06 3.26E+06 3.06E+06 2.84E+06 Total 0.001250 0.001340 0.001420 0.001530 0.001660 0.001760 Shrinkage 0.000014 0.000033 0.000063 0.000100 0.000140 0.000170 Creep 0.000350 0.000420 0.000480 0.000550 0.000640 0.000710 Elastic 0.000880 0.000880 0.000880 0.000880 0.000880 0.000880 Creep coefficient 0.40 0.48 0.54 0.62 0.73 0.81 1F 14-day moist cure 50% Creep modulus 3.71E+06 3.51E+06 3.35E+06 3.16E+06 2.98E+06 2.92E+06

PAGE 200

201 Table B-1. Continued Total 0.001141 0.001313 0.0015 0.001724 0.001961 0.002115 Shrinkage 0.000051 0.000097 0.000154 0.000210 0.000261 0.000286 Elastic 0.000663 0.000663 0.000663 0.000663 0.000663 0.000663 Creep 0.000427 0.000553 0.000683 0.000851 0.001037 0.001166 Creep coefficient 0.64 0.83 1.16 1.28 1.56 1.76 40% Creep Modulus 2.21E+06 1.98E+06 1.80E+06 1.61E+06 1.46E+06 1.37E+06 Total 0.001471 0.001614 0.001811 0.002057 0.002306 0.002471 Shrinkage 0.000051 0.000097 0.000154 0.000210 0.000261 0.000286 Elastic 0.000803 0.000803 0.000803 0.000803 0.000803 0.000803 Creep 0.000617 0.000714 0.000854 0.001044 0.001242 0.001382 Creep coefficient 0.77 0.89 1.07 1.30 1.55 1.72 7-day moist cure 50% Creep Modulus 2.10E+06 1.97E+06 1.80E+06 1.59E+06 1.42E+06 1.32E+06 Total 0.001114 0.001244 0.00139 0.001601 0.001834 0.001955 Shrinkage 0.000031 0.000069 0.000112 0.000173 0.000233 0.000258 Elastic 0.000669 0.000669 0.000669 0.000669 0.000669 0.000669 Creep 0.000414 0.000506 0.000609 0.000759 0.000932 0.001028 Creep coefficient 0.62 0.76 0.91 1.13 1.39 1.54 40% Creep Modulus 2.45E+06 2.28E+06 2.09E+06 1.85E+06 1.66E+06 1.55E+06 Total 0.001385 0.001557 0.00176 0.001972 0.002232 0.002398 Shrinkage 0.000031 0.000069 0.000112 0.000173 0.000233 0.000258 Elastic 0.000842 0.000842 0.000842 0.000842 0.000842 0.000842 Creep 0.000512 0.000646 0.000806 0.000957 0.001157 0.001298 Creep coefficient 0.61 0.77 0.96 1.14 1.37 1.54 2F 14-day moist cure 50% Creep Modulus 2.45E+06 2.23E+06 2.02E+06 1.85E+06 1.66E+06 1.55E+06

PAGE 201

202 Table B-1. Continued Total 0.001032 0.001165 0.001318 0.001477 0.001669 0.001796 Shrinkage 0.000040 0.000073 0.000124 0.000177 0.000221 0.000248 Elastic 0.000609 0.000609 0.000609 0.000609 0.000609 0.000609 Creep 0.000383 0.000483 0.000585 0.000691 0.000839 0.000939 Creep coefficient 0.61 0.77 0.93 1.10 1.33 1.49 40% Creep modulus 3.05E+06 2.77E+06 2.53E+06 2.33E+06 2.09E+06 1.96E+06 Total 0.001221 0.00139 0.001575 0.001764 0.00199 0.002132 Shrinkage 0.000040 0.000073 0.000124 0.000177 0.000221 0.000248 Elastic 0.000751 0.000751 0.000751 0.000751 0.000751 0.000751 Creep 0.000430 0.000566 0.000700 0.000836 0.001018 0.001133 Creep coefficient 0.57 0.75 0.93 1.11 1.36 1.51 7-day moist cure 50% Creep modulus 3.20E+06 2.87E+06 2.61E+06 2.38E+06 2.14E+06 2.01E+06 Total 0.000957 0.001093 0.001217 0.001381 0.001557 0.001686 Shrinkage 0.000021 0.000047 0.000087 0.000137 0.000182 0.000217 Elastic 0.000633 0.000633 0.000633 0.000633 0.000633 0.000633 Creep 0.000303 0.000413 0.000497 0.000611 0.000742 0.000836 Creep coefficient 0.48 0.65 0.79 0.97 1.17 1.32 40% Creep modulus 3.52E+06 3.15E+06 2.92E+06 2.76E+06 2.41E+06 2.27E+06 Total 0.001254 0.001389 0.001537 0.001700 0.001890 0.002023 Shrinkage 0.000021 0.000047 0.000087 0.000137 0.000182 0.000217 Elastic 0.000776 0.000776 0.000776 0.000776 0.000776 0.000776 Creep 0.000457 0.000566 0.000674 0.000787 0.000932 0.001030 Creep coefficient 0.59 0.73 0.87 1.01 1.20 1.33 3F 14-day moist cure 50% Creep modulus 3.34E+06 3.07E+06 2.84E+06 2.72E+06 2.41E+06 2.27E+06

PAGE 202

203 Table B-1. Continued Total 0.001060 0.001200 0.001340 0.001510 0.001680 0.001810 Shrinkage 0.000037 0.000073 0.000120 0.000170 0.000230 0.000270 Elastic 0.000600 0.000600 0.000600 0.000600 0.000600 0.000600 Creep 0.000420 0.000530 0.000630 0.000740 0.000850 0.000940 Creep coefficient 0.71 0.89 1.05 1.24 1.42 1.57 40% Creep modulus 2.95E+06 2.68E+06 2.47E+06 2.28E+06 2.09E+06 1.98E+06 Total 0.001400 0.001523 0.001642 0.001804 0.001984 0.002120 Shrinkage 0.000037 0.000073 0.000120 0.000170 0.000230 0.000270 Elastic 0.000703 0.000703 0.000703 0.000703 0.000703 0.000703 Creep 0.00066 0.000747 0.000819 0.000931 0.001051 0.001147 Creep coefficient 0.94 1.06 1.17 1.32 1.50 1.63 7-day moist cure 50% Creep modulus 2.79E+06 2.52E+06 2.32E+06 2.13E+06 1.96E+06 1.85E+06 Total 0.001078 0.001166 0.001259 0.001386 0.001543 0.001654 Shrinkage 0.000021 0.000042 0.000080 0.000132 0.000186 0.000223 Elastic 0.000571 0.000571 0.000571 0.000571 0.000571 0.000571 Creep 0.000486 0.000553 0.000608 0.000683 0.000786 0.000860 Creep coefficient 0.85 0.97 1.06 1.20 1.38 1.51 40% Creep modulus 3.90E+06 2.68E+06 2.47E+06 2.31E+06 2.09E+06 1.98E+06 Total 0.001208 0.001361 0.001518 0.001699 0.001886 0.002020 Shrinkage 0.000021 0.000042 0.000080 0.000132 0.000186 0.000223 Elastic 0.000702 0.000702 0.000702 0.000702 0.000702 0.000702 Creep 0.000485 0.000617 0.000736 0.000865 0.000998 0.001095 Creep coefficient 0.69 0.88 1.05 1.23 1.42 1.56 4F 14-day moist cure 50% Creep modulus 3.90E+06 2.68E+06 2.47E+06 2.30E+06 2.09E+06 1.98E+06

PAGE 203

204 Table B-1. Continued Total 0.001168 0.001299 0.001423 0.001587 0.001744 0.00184 Shrinkage 0.000044 0.000088 0.000130 0.000170 0.000201 0.000216 Elastic 0.000669 0.000669 0.000669 0.000669 0.000669 0.000669 Creep 0.000455 0.000542 0.000624 0.000748 0.000874 0.000955 Creep coefficient 0.409 0.580 0.683 1.101 1.320 1.476 40% Creep modulus 2.99E+06 2.69E+06 2.49E+06 2.28E+06 2.09E+06 1.98E+06 Total 0.001455 0.00162 0.001783 0.001977 0.002175 0.002299 Shrinkage 0.000044 0.000088 0.000130 0.000170 0.000201 0.000216 Elastic 0.000846 0.000846 0.000846 0.000846 0.000846 0.000846 Creep 0.000565 0.000686 0.000807 0.000961 0.001128 0.001237 Creep coefficient 0.67 0.81 0.95 1.14 1.33 1.46 7-day moist cure 50% Creep modulus 2.99E+06 2.69E+06 2.49E+06 2.28E+06 2.09E+06 1.98E+06 Total 0.001222 0.001323 0.001439 0.001594 0.001747 0.001834 Shrinkage 0.000043 0.000074 0.000110 0.000149 0.000178 0.000193 Elastic 0.000718 0.000718 0.000718 0.000718 0.000718 0.000718 Creep 0.000461 0.000531 0.000611 0.000727 0.000851 0.000923 Creep coefficient 0.64 0.74 0.85 1.01 1.19 1.29 40% Creep modulus 3.00E+06 2.79E+06 2.60E+06 2.38E+06 2.19E+06 2.11E+06 Total 0.001464 0.001596 0.001747 0.001937 0.002118 0.002212 Shrinkage 0.000043 0.000074 0.000110 0.000149 0.000178 0.000193 Elastic 0.000889 0.000889 0.000889 0.000889 0.000889 0.000889 Creep 0.000532 0.000633 0.000748 0.000899 0.001051 0.001130 Creep coefficient 0.62 0.74 0.87 1.04 1.22 1.31 5S 14-day moist cure 50% Creep modulus 2.99E+06 2.79E+06 2.60E+06 2.38E+06 2.19E+06 2.11E+06

PAGE 204

205 Table B-1. Continued Total 0.000975 0.001105 0.001255 0.001405 0.001600 0.001758 Shrinkage 0.000042 0.000082 0.000123 0.000157 0.000183 0.000196 Elastic 0.000670 0.000670 0.000670 0.000670 0.000670 0.000670 Creep 0.000263 0.000353 0.000462 0.000588 0.000747 0.000892 Creep coefficient 0.39 0.54 0.70 0.90 1.15 1.34 40% Creep modulus 3.58E+06 3.22E+06 2.91E+06 2.65E+06 2.38E+06 2.36E+06 Total 0.001194 0.001391 0.001550 0.001707 0.001901 0.002048 Shrinkage 0.000042 0.000082 0.000123 0.000157 0.000183 0.000196 Elastic 0.000837 0.000837 0.000837 0.000837 0.000837 0.000837 Creep 0.000325 0.000472 0.000570 0.000713 0.000891 0.001015 Creep coefficient 0.41 0.54 0.69 0.87 1.08 1.25 7-day moist cure 50% Creep modulus 3.54E+06 3.15E+06 2.89E+06 2.62E+06 2.31E+06 2.30E+06 Total 0.001037 0.001164 0.001291 0.001448 0.001648 0.001796 Shrinkage 0.000038 0.000076 0.000114 0.000141 0.000163 0.000177 Elastic 0.000692 0.000692 0.000692 0.000692 0.000692 0.000692 Creep 0.000307 0.000396 0.000485 0.000615 0.000793 0.000927 Creep coefficient 0.43 0.57 0.71 0.89 1.11 1.27 40% Creep modulus 3.70E+06 3.40E+06 3.15E+06 2.87E+06 2.56E+06 2.21E+06 Total 0.001263 0.001467 0.001567 0.001727 0.001941 0.002104 Shrinkage 0.000038 0.000076 0.000114 0.000141 0.000163 0.000177 Elastic 0.000854 0.000854 0.000854 0.000854 0.000854 0.000854 Creep 0.000371 0.000537 0.000599 0.000732 0.000924 0.001073 Creep coefficient 0.44 0.57 0.70 0.87 1.06 1.21 6S 14-day moist cure 50% Creep modulus 3.69E+06 3.35E+06 3.12E+06 2.85E+06 2.51E+06 2.10E+06

PAGE 205

206 Table B-1. Continued Total 0.000907 0.001094 0.001264 0.001399 0.001561 0.001656 Shrinkage 0.000039 0.000080 0.000126 0.000170 0.000202 0.000223 Elastic 0.000519 0.000519 0.000519 0.000519 0.000519 0.000519 Creep 0.000349 0.000495 0.000619 0.00071 0.00084 0.000914 Creep coefficient 0.67 0.95 1.19 1.37 1.62 1.76 40% Creep modulus 2.66E+06 2.33E+06 2.11E+06 1.92E+06 1.74E+06 1.65E+06 Total 0.001101 0.001285 0.001486 0.001664 0.001836 0.001941 Shrinkage 0.000039 0.000080 0.000126 0.000170 0.000202 0.000223 Elastic 0.000616 0.000616 0.000616 0.000616 0.000616 0.000616 Creep 0.000446 0.000589 0.000744 0.000878 0.001018 0.001102 Creep coefficient 0.72 0.96 1.21 1.43 1.65 1.79 7-day moist cure 50% Creep modulus 2.78E+06 2.45E+06 2.17E+06 1.98E+06 1.81E+06 1.72E+06 Total 0.000948 0.001081 0.001209 0.001384 0.001556 0.001651 Shrinkage 0.000038 0.000073 0.000111 0.000148 0.000183 0.000204 Elastic 0.000546 0.000546 0.000546 0.000546 0.000546 0.000546 Creep 0.000364 0.000462 0.000552 0.00069 0.000827 0.000901 Creep coefficient 0.67 0.85 1.01 1.26 1.51 1.65 40% Creep modulus 2.84E+06 2.57E+06 2.36E+06 2.09E+06 1.89E+06 1.79E+06 Total 0.001160 0.001308 0.001466 0.001646 0.001821 0.001921 Shrinkage 0.000038 0.000073 0.000111 0.000148 0.000183 0.000204 Elastic 0.000643 0.000643 0.000643 0.000643 0.000643 0.000643 Creep 0.000479 0.000592 0.000712 0.000855 0.000995 0.001074 Creep coefficient 0.74 0.92 1.11 1.33 1.55 1.67 7S 14-day moist cure 50% Creep modulus 2.78E+06 2.52E+06 2.30E+06 2.08E+06 1.90E+06 1.82E+06

PAGE 206

207 Table B-1. Continued Total 0.001131 0.001263 0.001409 0.000157 0.001762 0.001914 Shrinkage 0.000073 0.000123 0.000161 0.000194 0.000228 0.000250 Elastic 0.000614 0.000614 0.000614 0.000614 0.000614 0.000614 Creep 0.000443 0.000526 0.000633 0.000761 0.000920 0.001050 Creep coefficient 0.72 0.86 1.03 1.24 1.50 1.71 40% Creep modulus 2.71E+06 2.53E+06 2.34E+06 2.04E+06 1.82E+06 1.68E+06 Total 0.001296 0.001438 0.001606 0.001821 0.002048 0.002227 Shrinkage 0.000073 0.000123 0.000161 0.000194 0.000228 0.000250 Elastic 0.000722 0.000722 0.000722 0.000722 0.000722 0.000722 Creep 0.000500 0.000592 0.000722 0.000904 0.001098 0.001254 Creep coefficient 0.69 0.82 1.00 1.25 1.52 1.74 7-day moist cure 50% Creep modulus 2.56E+06 2.38E+06 2.17E+06 1.97E+04 1.77E+06 1.63E+06 Total 0.001140 0.001262 0.001394 0.001549 0.001733 0.001889 Shrinkage 0.000050 0.000098 0.000136 0.000169 0.000202 0.000230 Elastic 0.000654 0.000654 0.000654 0.000654 0.000654 0.000654 Creep 0.000436 0.000510 0.000604 0.000726 0.000877 0.001004 Creep coefficient 0.67 0.78 0.92 1.11 1.34 1.53 40% Creep modulus 2.92E+06 2.68E+06 2.51E+06 2.26E+06 2.02E+06 1.87E+06 Total 0.001374 0.001524 0.001677 0.001881 0.002118 0.002294 Shrinkage 0.000050 0.000098 0.000136 0.000169 0.000202 0.000230 Elastic 0.000831 0.000831 0.000831 0.000831 0.000831 0.000831 Creep 0.000493 0.000596 0.000710 0.000881 0.001084 0.001233 Creep coefficient 0.59 0.72 0.85 1.06 1.30 1.48 8S 14-day moist cure 50% Creep modulus 2.71E+06 2.53E+06 2.34E+06 2.14E+06 1.93E+06 1.78E+06

PAGE 207

208 Table B-1. Continued Total 0.001118 0.001231 0.001380 0.001528 0.001684 0.001792 Shrinkage 0.000049 0.000096 0.000162 0.000226 0.000288 0.000322 Elastic 0.000626 0.000626 0.000626 0.000626 0.000626 0.000626 Creep 0.000443 0.000510 0.000592 0.000677 0.000771 0.000844 Creep coefficient 0.71 0.82 0.95 1.08 1.23 1.35 40% Creep modulus 1.99E+06 1.85E+06 1.74E+06 1.62E+06 1.51E+06 1.43E+06 Total 0.001337 0.001487 0.001642 0.001811 0.001987 0.002112 Shrinkage 0.000049 0.000096 0.000162 0.000226 0.000288 0.000322 Elastic 0.000767 0.000767 0.000767 0.000767 0.000767 0.000767 Creep 0.000521 0.000624 0.000713 0.000819 0.000932 0.001023 Creep coefficient 0.68 0.81 0.93 1.07 1.22 1.33 7-day moist cure 50% Creep modulus 1.92E+06 1.81E+06 1.69E+06 1.58E+06 1.47E+06 1.40E+06 Total 0.001169 0.001272 0.001392 0.001507 0.001633 0.001714 Shrinkage 0.000046 0.000081 0.000137 0.000189 0.000239 0.000276 Elastic 0.000677 0.000677 0.000677 0.000677 0.000677 0.000677 Creep 0.000447 0.000514 0.000579 0.000641 0.000718 0.000762 Creep coefficient 0.66 0.76 0.86 0.95 1.06 1.13 40% Creep modulus 2.29E+06 2.12E+06 2.00E+06 1.91E+06 1.79E+06 1.72E+06 Total 0.001297 0.001433 0.001564 0.001691 0.001836 0.001940 Shrinkage 0.000046 0.000081 0.000137 0.000189 0.000239 0.000276 Elastic 0.000777 0.000777 0.000777 0.000777 0.000777 0.000777 Creep 0.000474 0.000576 0.000651 0.000726 0.000820 0.000888 Creep coefficient 0.61 0.74 0.84 0.93 1.06 1.14 9LF 14-day moist cure 50% Creep modulus 2.21E+06 2.08E+06 1.98E+06 1.88E+06 1.79E+06 1.72E+06

PAGE 208

209 Table B-1. Continued Total 0.001206 0.001314 0.001433 0.001559 0.001694 0.001789 Shrinkage 0.000070 0.000130 0.000198 0.000260 0.000319 0.000360 Elastic 0.000546 0.000546 0.000546 0.000546 0.000546 0.000546 Creep 0.000590 0.000639 0.000690 0.000753 0.000830 0.000883 Creep coefficient 1.08 1.17 1.26 1.38 1.52 1.62 40% Creep modulus 1.16E+06 1.10E+06 1.04E+06 0.97E+06 0.92E+06 0.88E+06 Total 0.001517 0.001648 0.001780 0.001939 0.002098 0.002224 Shrinkage 0.000070 0.000130 0.000198 0.000260 0.000319 0.000360 Elastic 0.000721 0.000721 0.000721 0.000721 0.000721 0.000721 Creep 0.000726 0.000797 0.000861 0.000958 0.001058 0.001143 Creep coefficient 1.01 1.10 1.19 1.33 1.47 1.59 7-day moist cure 50% Creep modulus 1.03E+06 0.99E+06 0.95E+06 0.90E+06 0.85E+06 0.82E+06 Total 0.000874 0.000898 0.000941 0.000997 0.001062 0.001116 Shrinkage 0.000038 0.000090 0.000152 0.000209 0.000279 0.000320 Elastic 0.000781 0.000898 0.001083 0.001123 0.001274 0.001377 Creep 0.000276 0.000337 0.000380 0.000486 0.000501 0.000554 Creep coefficient 0.62 0.74 0.82 0.93 1.05 1.16 40% Creep modulus 1.67E+06 1.58E+06 1.51E+06 1.42E+06 1.33E+06 1.26E+06 Total 0.001169 0.001286 0.001406 0.001539 0.001694 0.001809 Shrinkage 0.000038 0.000090 0.000152 0.000209 0.000279 0.000320 Elastic 0.000713 0.000713 0.000713 0.000713 0.000713 0.000713 Creep 0.000418 0.000482 0.000540 0.000617 0.000702 0.000776 Creep coefficient 0.59 0.68 0.76 0.87 0.99 1.09 10LS 14-day moist cure 50% Creep modulus 1.67E+06 1.58E+06 1.51E+06 1.42E+06 1.33E+06 1.26E+06

PAGE 209

210 Table B-1. Continued Total 0.001023 0.001173 0.001333 0.001532 0.001750 0.001873 Shrinkage 0.000032 0.000061 0.000109 0.000161 0.000204 0.000229 Elastic 0.000601 0.000601 0.000601 0.000601 0.000601 0.000601 Creep 0.000390 0.000511 0.000623 0.000769 0.000944 0.001043 Creep coefficient 0.65 0.85 1.04 1.28 1.57 1.74 40% Creep modulus 2.61E+06 2.33E+06 2.11E+06 1.89E+06 1.67E+06 1.57E+06 Total 0.001334 0.001494 0.001690 0.001992 0.002171 0.002323 Shrinkage 0.000032 0.000061 0.000109 0.000161 0.000204 0.000229 Elastic 0.000777 0.000777 0.000777 0.000777 0.000777 0.000777 Creep 0.000526 0.000657 0.000804 0.000984 0.001190 0.001318 Creep coefficient 0.68 0.85 1.04 1.27 1.53 1.70 2GF 14-day moist cure 50% Creep modulus 2.48E+06 2.26E+06 2.05E+06 1.84E+06 1.64E+06 1.54E+06 Total 0.000811 0.000931 0.001084 0.001243 0.001428 0.001541 Shrinkage 0.000024 0.000047 0.000076 0.000113 0.000157 0.000183 Elastic 0.000530 0.000530 0.000530 0.000530 0.000530 0.000530 Creep 0.000257 0.000354 0.000479 0.000600 0.000741 0.000828 Creep coefficient 0.48 0.67 0.90 1.33 1.40 1.56 40% Creep modulus 3.69E+06 3.28E+06 2.88E+06 2.57E+06 2.29E+06 2.14E+06 Total 0.001043 0.001187 0.001362 0.001549 0.001747 0.001879 Shrinkage 0.000024 0.000047 0.000076 0.000113 0.000157 0.000183 Elastic 0.000666 0.000666 0.000666 0.000666 0.000666 0.000666 Creep 0.000353 0.000474 0.000621 0.000770 0.000924 0.001030 Creep coefficient 0.53 0.71 0.93 1.16 1.39 1.55 3GF 14-day moist cure 50% Creep modulus 3.56E+06 3.19E+06 2.82E+06 2.53E+06 2.28E+06 2.14E+06

PAGE 210

211 Table B-1. Continued Total 0.001024 0.001163 0.001296 0.001454 0.001615 0.001690 Shrinkage 0.000039 0.000064 0.000104 0.000140 0.000168 0.000184 Elastic 0.000556 0.000556 0.000556 0.000556 0.000556 0.000556 Creep 0.000429 0.000543 0.000636 0.000758 0.000891 0.000950 Creep coefficient 0.77 0.98 1.14 1.36 1.60 1.71 40% Creep modulus 2.87E+06 2.57E+06 2.35E+06 2.13E+06 1.94E+06 1.86E+06 Total 0.001261 0.001427 0.001594 0.001783 0.001977 0.002084 Shrinkage 0.000039 0.000064 0.000104 0.000140 0.000168 0.000184 Elastic 0.000703 0.000703 0.000703 0.000703 0.000703 0.000703 Creep 0.000519 0.000660 0.000787 0.000940 0.001106 0.001197 Creep coefficient 0.74 0.94 1.12 1.34 1.57 1.70 5GS 14-day moist cure 50% Creep modulus 2.85E+06 2.55E+06 2.35E+06 2.13E+06 1.94E+06 1.84E+06 Total 0.000953 0.001078 0.001213 0.001383 0.001551 0.001627 Shrinkage 0.000043 0.000074 0.000100 0.000131 0.000162 0.000181 Elastic 0.000517 0.000517 0.000517 0.000517 0.000517 0.000517 Creep 0.000393 0.000487 0.000597 0.000736 0.000872 0.000929 Creep coefficient 0.76 0.94 1.15 1.42 1.69 1.80 40% Creep modulus 2.91E+06 2.64E+06 2.38E+06 2.11E+06 1.90E+06 1.83E+06 Total 0.001208 0.001361 0.001517 0.001708 0.001899 0.001977 Shrinkage 0.000043 0.000074 0.000100 0.000131 0.000162 0.000181 Elastic 0.000652 0.000652 0.000652 0.000652 0.000652 0.000652 Creep 0.000512 0.000634 0.000764 0.000924 0.001084 0.001143 Creep coefficient 0.79 0.97 1.17 1.42 1.66 1.75 7GS 14-day moist cure 50% Creep modulus 2.84E+06 2.57E+06 2.33E+06 2.10E+06 1.90E+06 1.84E+06

PAGE 211

212 LIST OF REFERENCES AASHTO, 2001. AASHTO LRFD Bridge Construc tion Specifications-2001 Interim Revisions. American Association of State Highway and Transportation Officials, Washington, D.C. ACI Committee 209, 1993. Prediction of Creep, Shrinkage, and Temperature Effects in Concrete Structures (ACI 209R-92). ACI Manual of Concre te Practice, American Concrete Institute, Detroit, MI, Part 1, pp.47. ACI 318-83, 1983. Building Code Requirements for reinforced concrete. American Concrete Institute, Detroit, Michigan, November 1983. Acker Paul, Ulm Franz-Josef, 2001. Creep and Sh rinkage of Concrete: Physical Origins and Practical Measurements. Nuclear Engineering and Design 203, pp.143. Aitcin, P-C. and Mehta, P. K. 1990. Effect of coarse aggreg ate characteristics on mechanical properties of high strength concrete. ACI Materi als Journal, Mar-Apr 1990, Vol. 87, No. 2, pp 103-107. Alexander, M. G.and Addis, B. J., 1992. Prope rties of High Strength Concrete Influenced by Aggregates and Interfacial Bond. Bond in Concrete: From Research to Practice. Proceedings of the CEB International Conferen ce held at Riga Technical University, Riga, Latvia, Oct. 15-17, Vol.2, Topics 3-7, pp.4-19 to 4-26. Aykut Cetin and Ramon L. Carrasquillo, 1998. High-Performance Concrete: Influence of Coarse Aggregates on Mechanical Properties. Materials Journal, Vo l.95, Issue 3, May 1, 1998. Baalbaki, W., Benmokrane, B., Chaallal, O., and Aitcin, P-C., 1991. Influence of coarse aggregate on elastic properties of high perf ormance concrete. ACI Materials Journal, SepOct 1991, Vol. 88, No. 5, pp 499-503. Baant, Z.P., Hauggaard A.B., Baweja S., Ulm Fr anz-Josef., 1997. Microprestress-Solidification Theory for Concrete Creep I: Aging and Drying Effects. Journal of Engineering Mechanics, Vol. 123, No. 11, November 1997, pp.1188-1194. Baant, Z.P., 2001. Prediction of concrete creep and shrinkage: past, present and future. Nuclear Engineering and Design, 203 (2001), pp.27. Beshr H., Almusallam A.A. and Maslehuddin M., 2003. Effect of coarse aggregate quality on the mechanical properties of high strength concre te. Construction and Building Materials, Volume 17, Number 2, March 2003, pp. 97-103(7). Bisschop, J. and Van Mier, J.G.M., 2000. Effect of Aggregates on Dr ying Shrinkage Microcracking in Cement-based Materials. UEF conference, Mt-Tremblant, Canada, August, 2000, (Con. Sc. Techn).

PAGE 212

213 Branson, Dan E. and Christiason, M.L.. Time Dependent Concrete Properties Related to Designing-strength and Elasticity properties, Creep and Shrinkage, Designing for Effects of Creep, Shrinkage and Temper ature in Concrete Structures. ACI, Publication SP-27, pp.257-278. Branson, D.E.; Meyers, B.L.; and Kripanarayan an, K.M, 1970. Loss of Prestress, Camber, and Deflection of Noncomposite and Composite Stru ctures Using Different Weight Concretes. Final Report No. 70-6, Iowa Highway Commission, Aug. 1970, Pp 1-229. Branson, D.E.; and Christiason, M.L., 1971. Ti me Dependent Concrete Properties Related to Design-Strength and Elastic Properties, Creep and Shrinkage. Symposium on Creep, Shrinkage, and Temperature Effects, SP-27-13, American Concrete Institute, Detroit 1971, PP.257-277. Carino, N.J., and H.S.Lew, 1982. Re-examination of the Relation between Splitting Tensile and Compressive Strength of No rmal Weight Concrete. Jour nal of American Concrete Institute, Vol.79, No.3, May-June 1982, pp.214-219. CEB-FIP, 1990. Model Code for Co ncrete Structures, first draft, Bulletin d information No.195. Comit-Euro-International Du Bton-Fdration Internationale De La Prcontrainte, Paris, 1990. Chi, J.M., Huang, R., Yang, C.C., Chang, J.J ., 2003. Effect of aggregate properties on the strength and stiffness of li ghtweight concrete. Cement & Concrete Composites, 25 (2003), pp.197. Collins, T. M., 1989. Proportioning High-Strength Concrete to Control Creep and Shrinkage. ACI Materials Journal, Nov-Dec, Vol. 86, No. 6, pp.576-580. Collins, T. M., 1989. Proportioning high strength conc rete to control creep and shrinkage. ACI Materials Journal, Nov-Dec 1989, Vol. 86, No. 6, pp 576-580. Cristescu, N.D, Hunsche, U., 1998. Time Effects in Rock Mechanics. John Wiley & Sons, ISBN 0471955175, 1998. Cristescu, N.D, 1989. Rock Rheology. Kluwer Academic Publishers, ISBN 90-247-3660-9, 1989. Ezeldin, A. S. and Aitcin, P-C. 1991. Effect of coarse aggregate on the behavior of normal and high strength concretes. Cement, Concrete a nd Aggregates, Winter 1991, Vol. 13, No. 2, pp 121-124. FDOT, 2002. Structural De sign Guidelines for Load and Resi stance Factor Design. Structural Design Office, Tallahassee, Florida FHWA, 1994. An Analysis of Transfer and De velopment Lengths for Pre-tensioned Concrete Structures. Report No. FHWA-RD-94-049, December 1994.

PAGE 213

214 Gesoglu Mehmet, Zturan Turan*, Gneyisi Erha n, 2004. Shrinkage cracking of lightweight concrete made with cold-bonded fly ash aggr egates. Cement and Concrete Research 34 (2004), pp.1121-1130. Giaccio, G., Rocco, C., Violini, D., Zappitelli, J., and Zerbino, R., 1992. High strength concrete incorporating different coarse aggregates. AC I Materials Journal, May-Jun 1992, Vol. 89, No. 3, pp 242-246. Hermite, R.L, 1960. Volume changes of concrete. Proc. 4th int. symp. On the Chemistry of cement, Washington DC, pp.659-694. Holm, Thomas. A., 2001. lightweight aggr egate concrete. STP 169C, ASTM, pp.522~531. Hua, C., Acker, P., Ehrlacher, A., 1995. Analys is and modeling of the autogenous shrinkage of hardening cement paste-I. Mode ling at macroscopic scale. Ce ment and Concrete Research, Vol.25, No7 (1995), pp.1457-1468. Jensen, H. E., 1992. State-of art report for high strength concrete shrinkage and creeping. Doctoral Thesis, Afdelingen for Baerende Konstruktioner, Technical University of Denmark, Lyngby, Denmark, 1992, 71 pp. (T ext in Danish; Summary in English). John M. Lybas, 1990. Reconciliation Study of Creep in Florida Concrete. Final Report, Structural and Material Res earch Report No. 90-1. Department of Civil Engineering, University of Florida, Gainesville, 1990. Keeton, John R., Roll Frederic and Meyers, B.L.. Effects of Concrete Constituents, Environment, and Stress on the Creep and Shrinkage of Concrete. ACI Committee 209, subcommittee 1, Designing for Effects of Creep, Shrinkage a nd Temperature in Concrete Structures, Publication SP-27, pp.1-23. Larry C. Muszynski, James L. Lafrenz, and David H. Artman, 1997. Proportioning Concrete Mixtures with Graded Aggregates. Publication ASCE, Jun 24, 1997. Leming, M. L., 1990. Comparison of mechanical pr operties of high strength concrete made with different raw mateials. Tr ansportation Research Record, 1990, No. 1284, pp 23-30. Li, Jianyong, Yao, Yan, 2001. A study on creep and drying shrinkage of high performance concrete. Cement and Concrete Research 31 (2001), pp.1203-1206. Lindgard, J. and Smeplass, S. 1993. High strength concrete containing silica fume-impact of aggregate type on compressive strength and elastic modulus. Proceedings of the 4th International Conference on the Use of Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete, held May 3-8, 1992, Istanbul, Turkey; Sponsored by CANMET in Association with the American Concrete Institute and Others; Ed. by V. M. Malhotra; American Concrete Institute, Detroit, MI, 1993, Vol. 2, pp 1061-1074. (ACI SP-132).

PAGE 214

215 M..A.Cassaro, 1967. A Study of Creep in Light weight and Conventiona l Concretes. Final Report. Department of Civil Engineering and Florida Engineering and Industrial Experiment Station, University of Florida, Gainesville, Jan, 1967. Mang Tia, 1989. Field and laborat ory study of modulus of rupture and permeability of structural concretes in Florida. Final Report, Florida Department of Trans portation in cooperation with U.S. Department of Transportation and Federal Highway Admini stration. Department of Civil & Coastal Engineering, University of Florida, 1989. M. A. Rashid, M. A. Mansur, and P. Parama sivam, 2002. Correlations between Mechanical Properties of High-Strength Concrete. Materi als Journal, Volume 14, Issue 3, pp. 230-238 (May/June 2002). Mark G. Alexander, 1996. Aggregates and the Deformation Properties of Concrete. Materials Journal, Vol.93, Issue 6, Nov 1, 1996. Neville, A.M., 1996. Properties of Concrete (Fourth and Final Edition). John Wiley & Sons, Inc, New York. Neville A.M., 1965. Properties of Concrete (Fir st Edition). John Wiley & Sons, Inc, New York. Neville, A.M., 1957. Non-elastic Deformations in Concrete Structures. J. New Zealand Inst. E., 12, pp.114-120. Nilsen, A. U. and Aitcin, P-C., 1992. Propertie s of high strength concrete containing lightnormal, and heavyweight aggregate. Cement Concrete, and Aggreg ates, Summer 1992, Vol. 14, No. 1, pp 8-12. Ozyildirim, C. 2000. Evaluation of High-Pe rformance Concrete Pavement in Newport News, VA. Draft Interim Report, Virgin ia Transportation Research Council, Charlottesville. Ozyildirim, C. 2001. Evaluation of High-Pe rformance Concrete Pavement in Newport News, VA. Preprint Paper 01-3173. 80th Annual Meeting of the Transportation Research Board, Washington, DC Paulson, K. A., Nilson, A. H., Hover, K. C, 1991. Long Term Deflection of High-Strength Concrete Beams. ACI Materials Journal, Mar-Apr 1991, Vol. 88, No. 2, pp.197-206. P. C. Aitcin and P. K. Mehta, 1990. Effect of Coarse Aggregate Charac teristics on Mechanical Properties of High-Strength Concrete. Materials Journal, Vol. 37, Issue 2, March 1, 1990. Persson Bertil, 2001. A comparison between mechanic al properties of self-compacting concrete and the corresponding properties of normal conc rete. Cement and Concrete Research, 31 (2001), pp.193

PAGE 215

216 Phillieo, R.E.. Summary of Symposium on De signing for Effects of Shrinkage, Creep and Temperature, Designing for effects of creep shrinkage and temper ature in concrete structures. ACI, Publication SP-27, pp.247-253. Pichett, G., 1956. Effect of aggregate on sh rinkage of concrete and hypothesis concerning shrinkage. J. Amer. Concr. Inst., 52, pp.581-590. P. Zia, M. L. Leming, S. H. Ahmad, J. J. Schemmel, R. P. Elliott, and A. E. Naaman., 1993a. Mechanical Behavior of High Performance Concretes, Volume 1: Summary Report. Strategic Highway Research Program, National Research Council, Washington, D. C., xi, 98 pp. (SHRP-C-361). P. Zia, M. L. Leming, S. H. Ahmad, J. J. Schemmel, and R. P. Elliott. 1993b. Mechanical Behavior of High Performance Concretes, Vo lume 2: Production of High Performance Concrete. Strategic Highway Research Program National Research Council, Washington, D. C., xi, 92 pp. (SHRP-C-362). P. Zia, S. H. Ahmad, M. L. Leming, J. J. Schemmel, and R. P. Elliott. 1993c. Mechanical Behavior of High Performance Concretes, Volume 3: Very Early Strength Concrete. Strategic Highway Research Program, National Research Council, Washington, D. C., xi, 116 pp. (SHRP-C-363). P. Zia, S. H. Ahmad, M. L. Leming, J. J. Schemmel, and R. P. Elliott. 1993d. Mechanical Behavior of High Performance Concretes, Volume 4: High Early Strength Concrete. Strategic Highway Research Program, National Research Council, Washington, D. C., xi, 179 pp. (SHRP-C-364). P. Zia, S. H. Ahmad, M. L. Leming, J. J. Schemmel, and R. P. Elliott. 1993e. Mechanical Behavior of High Performance Concretes, Volume 5: Very High Strength Concrete. Strategic Highway Research Program, National Research Council, Washington, D. C., xi, 101 pp. (SHRP-C-365). Reichard, T.W., 1964. Creep and drying shrinkage of lightweight and normal weight concretes. Nat. Bur. Stand. Monograph, 74, Washington DC, March, 1964. Roberts, John.Thomas., 1951. The Elastic Propertie s of Concrete and Thei r Effects on Design. A Thesis for Master Degree, Univer sity of Florida, August, 1951. Rsch, H., Kordina, K. and Hilsdorf, H., 1963. De r einfluss des mineralogischen Charakters der Zuschlge auf das Kriechen von Beton. De utscher Ausschuss fr Stahlbeton, No. 146, pp.19-133. Russell, H. G., Larson, S. C, 1989. Thirteen Y ears of Deformations in Water Tower Place. ACI Structural Journal, Mar-Apr 1989, Vol. 86, No. 2, pp.182-191. Sarkar, S. L. and Aitcin, P-C, 1990. Importance of petrological, petrograp hical and mineralogical characteristics of aggregates in very hi gh strength concrete. ASTM Special Technical Publication, 1990, No. 1061, pp 129-144.

PAGE 216

217 Schlumpf Jrg, 2004. Self-compacting concrete structures in Swit zerland. Tunnelling and Underground Space Technology, 19 (2004) 480. Shideler, J.J., 1957. Lightweight aggregate concrete for structural use. J. Amer. Concr. Inst., 54, pp.299-328. Shih, T. S., Lee, G. C., and Chang, K. C.,1989. On static modulus of elasticity of normal weight concrete. Journal of Struct ural Engineering, Oct 1989, Vol. 115, No. 10, pp 2579-2587. Stock, A.F., Hannant, D.J. and Williams, R.I.T., 1979. The effect of aggregate concentration upon the strength and modulus of elasticity of concrete. Mag. Concr. Res., 31, No. 109, pp.225-234. Thomas, Jeffrey J. and Jennings, Hamlin M., 2001. Chemical Aging and the Colloidal Structure of the C-S-H Gel: Implication for Creep and Shrinkage. Creep, Shrinkage and Durability Mechanics of Concrete and Other Quasi-brittle Materials edited by F,-J. Ulm, Z.P. Baant and F.H. Wittmann. (2001), pp.33-38. Troxell, G.E., Raphael, J.M. and Davis, R.E., 1958. Long-time creep and shri nkage tests of plain and reinforced concrete. Proc. ASTM., 58, pp.1101-1120. Wu K.-R., Chen B., Yao W., Zhang D, 2001. Eff ect of coarse aggregate type on mechanical properties of high-performance concrete. Cement and Concrete Research, Volume 31, Number 10, Oct ober 2001, pp. 1421-1425(5). Zhou, F.P., Lydon, F.D. and Barr, B.I.G., 1995. E ffect of coarse aggreg ate on elastic modulus and compressive strength of high performance concrete. Cement and Concrete Research, Vol. 25, No. 1, pp.177-186. Zia, P., Leming, M.L., Ahmad, S.H. 1991. Hi gh-Performance Concrete : A State-of-the-Art Report. Strategic Highway Res earch Program, National Resear ch Council, Washington, D. C., (SHRP-C/FR-91-103; PB92-130087), pp.251. Zia, P., Ahmad, S.H., Leming, M.L., Schemmel, J. J., Elliott, R.P. 1993. Mechanical Behavior of High Performance Concretes. Volume 5: Very High Strength Concre te. Strategic Highway Research Program, National Research Counc il, Washington, D. C., xi, (SHRP-C-365), pp.101.

PAGE 217

218 BIOGRAPHICAL SKETCH Liu Yanjun, born in 1973 in China, is a civil engineer. He went to Shenyang Architectural and Civil En gineering Institute in 1993. Four years later, he earned his bachelors degree in civil engineering in 1997. Then, he got scholarship from China Building Materials Academy and worked on his Masters study in Material Science and Engineering. After three years, in 2000, he earned his Masters degree at China Building Materials Academy in Material Science and Engineering with minor focus on cement and concrete materials. After that, he worked for China Building Materials Academy for 2 years. Then, he obtained full schola rship from Civil and Coastal Engineering Department of University of Florida and involved PhD program on the research on cement and concrete materials. At la st, he achieved his PhD at the University of Florida in 2007.