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Concrete Containing Recycled Concrete Aggregate for Use in Concrete Pavement

Permanent Link: http://ufdc.ufl.edu/UFE0025075/00001

Material Information

Title: Concrete Containing Recycled Concrete Aggregate for Use in Concrete Pavement
Physical Description: 1 online resource (105 p.)
Language: english
Creator: Bekoe, Patrick
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: aggregates, concrete, recycled
Civil and Coastal Engineering -- Dissertations, Academic -- UF
Genre: Civil Engineering thesis, M.E.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Our study evaluated the feasibility of using concrete containing recycled concrete aggregate (RCA) in concrete pavement application. Concrete containing 0%, 25% and 50% of RCA were produced in the laboratory and their properties vital to the performance of concrete pavement evaluated. Result from the laboratory testing program indicates that the compressive strength and elastic modulus is reduced slightly as the percentage of RCA increases. The flexural strength, splitting tensile strength and coefficient of thermal expansion is about the same for concrete containing virgin aggregate and RCA. The free shrinkage increases slightly as the percentage of RCA increases. From the measured properties, a finite element analysis was performed to determine how the concretes containing the different amounts of RCA would perform if they were used in a typical concrete pavement in Florida. The analysis from the finite element model determined the maximum stresses under critical temperature and load conditions. The potential performance of the different pavements was evaluated based on the computed maximum stress to the flexural strength ratio. The maximum stress to flexural strength ratio in the pavement was found to be about the same as the percentage of RCA increases. This indicates that RCA can be used successfully in concrete pavement without affecting the performance
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 Patrick Bekoe.
Thesis: Thesis (M.E.)--University of Florida, 2009.
Local: Adviser: Tia, Mang.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0025075:00001

Permanent Link: http://ufdc.ufl.edu/UFE0025075/00001

Material Information

Title: Concrete Containing Recycled Concrete Aggregate for Use in Concrete Pavement
Physical Description: 1 online resource (105 p.)
Language: english
Creator: Bekoe, Patrick
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: aggregates, concrete, recycled
Civil and Coastal Engineering -- Dissertations, Academic -- UF
Genre: Civil Engineering thesis, M.E.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Our study evaluated the feasibility of using concrete containing recycled concrete aggregate (RCA) in concrete pavement application. Concrete containing 0%, 25% and 50% of RCA were produced in the laboratory and their properties vital to the performance of concrete pavement evaluated. Result from the laboratory testing program indicates that the compressive strength and elastic modulus is reduced slightly as the percentage of RCA increases. The flexural strength, splitting tensile strength and coefficient of thermal expansion is about the same for concrete containing virgin aggregate and RCA. The free shrinkage increases slightly as the percentage of RCA increases. From the measured properties, a finite element analysis was performed to determine how the concretes containing the different amounts of RCA would perform if they were used in a typical concrete pavement in Florida. The analysis from the finite element model determined the maximum stresses under critical temperature and load conditions. The potential performance of the different pavements was evaluated based on the computed maximum stress to the flexural strength ratio. The maximum stress to flexural strength ratio in the pavement was found to be about the same as the percentage of RCA increases. This indicates that RCA can be used successfully in concrete pavement without affecting the performance
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 Patrick Bekoe.
Thesis: Thesis (M.E.)--University of Florida, 2009.
Local: Adviser: Tia, Mang.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0025075:00001


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1 CONCRETE CONTAINING RECYCLED CONCRETE AGGREGATE FOR USE IN CONCRETE PAVEMENT By PATRICK AMOAH BEKOE A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING UNIVERSITY OF FLORIDA 2009

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2 2009 Patrick Amoah Bekoe

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3 To Rita Amoah Bekoe the wife of my youth, N hyirah Amoah Bekoe our lovely son and all who have supported me to come this far

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4 ACKNOWLEDGMENTS I will f irst of all want to thank the Almighty God for His protection over my life and for His Mercies, Grace, Favor and Unfailing Love for me. Such a compilation would not have come to fruition without the direction, support and en couragement of my supervisory committee chair, Dr. Mang Tia and I want to express my gratitude to him for what he has done for me during the period I have been under his tutelage. My sincer e appreciation is also extended to my committee members, Dr. Reynaldo Roque and Dr. Fazil T. Najafi for their help and support. I am thankful to the Ministry of Transportation and the Depa rtment of Feeder roads of Ghana for giving me the unique opportunity to pursue my masters in this prestigious university. Special thanks go to the following gallant offi ces who contributed immensely to my coming here; Mr. John Osei Asamosah (Chief Director Ministry of Transportation), Mr. E.N.K. Ashong (Director of Feeder Roads) Mr. Richard Abba n (Director of Human resources, Ministry of Transportation) and Dr. Dani el D. Darku (Director Department of Urban Roads). I am thankful to Florida Department of Transportation [FDOT] for sponsoring this research. I am grateful to all FDOT office pers onnel particularly to Michael Bergin, Charles Ishee, Richard DeLorenzo, Christopher Ferraro and Craig Roberts. My appreciation is also conveyed to the staff of the Department of Ci vil and Coastal Engineering, especially Nancy McIlrath-Glanville, Donna Moss, Doretha Ra y, Carolyn Carpenter, George Lopp, Murphy Anthony, Chuck Broward, Nard Hubert and others. This is also an opportune time to thank my loving and understanding wife for all the sacrifices she made for me to co me this far. God bless you. I am indebted to Akwesi F. Mensah and Joyce Dankyi for all the support and assistance they provided me during this period. I am also thankful to the help provided by Nabil Hossiney, Li Qiang, Abhay P. Singh, Scott Ellis, Guangming Wang, Chulseung Koh Yu Chen and the host of friends whose name I can mention.

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5 Finally, I will want to thank all my friends and family who have supported me on this journey especially my father, Lawrence Amaoh Bekoe, my beloved late mother Bernice Oye Sakyi, my dear brother Michael Ankamah Beko e and my aunties, Madam Evelyn Asiedu Ofie, Mrs. Agnes Arhin and Mrs. Owusu Bennoah God bless you all.

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6 TABLE OF CONTENTS page ACKNOWLEDGMENTS...............................................................................................................4 LIST OF TABLES................................................................................................................. ..........9 LIST OF FIGURES.......................................................................................................................11 ABSTRACT...................................................................................................................................14 CHAP TER 1 INTRODUCTION..................................................................................................................15 1.1 Background and Research Need ................................................................................... 15 1.2 Hypothesis of Research ................................................................................................. 16 1.3 Research O bjectives...................................................................................................... 16 2 LITERATURE REVIEW.......................................................................................................17 2.1 Introduction ................................................................................................................... 17 2.2 Historical O verview of Concrete Recycling................................................................. 17 2.3 Current Developm ent in Concrete Recycling............................................................... 17 2.4 General Properties of RCA from Concrete Pavem ent..................................................20 2.4.1 Production of Recycled Concrete Aggregates .................................................. 20 2.4.2 Physical and Mechanical Properties of Coarse Recycled Aggregates ..............21 2.4.3 Gradation ........................................................................................................... 22 2.4.4 Particle Shape and Texture................................................................................22 2.4.5 Specific Gravity ................................................................................................ 23 2.4.6 Density ............................................................................................................ 23 2.4.7 Water Absorption .............................................................................................. 23 2.4.8 Los Angeles Abrasion L oss..............................................................................24 2.4.9 Sulfate Soundness .............................................................................................24 2.5 Properties of Concrete m ade from RCA....................................................................... 24 2.5.1 Fresh Concrete ..................................................................................................24 2.5.1.1 Mix design .......................................................................................... 24 2.5.1.2 Water cem ent ratio.............................................................................. 25 2.5.1.2 Unit weight and air content .................................................................25 2.5.1.3 Fine to coarse aggregate ratio .............................................................25 2.5.2 Hardened Concrete ............................................................................................26 2.5.2.1 Com pressive strength.......................................................................... 26 2.5.2.2 Tensile and flexural strength .............................................................. 27 2.5.2.3 Elastic m odulus...................................................................................27

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7 2.5.2.4 Drying shrinkage ................................................................................27 2.5.2.5 Coefficient of therm al expansion........................................................ 28 2.5.2.6 Creep ...................................................................................................28 2.5.2.7 Perm eability........................................................................................ 28 2.5.2.8 Freeze and thawing resistance ............................................................ 29 2.5.2.9 Carbonation, chloride penetration and reinforcem ent corrosion........ 29 3 MATERIALS AND TEST METHODS................................................................................. 30 3.1 Introduction ................................................................................................................... 30 3.2 Concrete Mix Proportions .............................................................................................30 3.3 Mix Ingredients .............................................................................................................30 3.4 Fabrication and Curing of Concrete Specim en.............................................................38 3.5 Concrete Preparation ..................................................................................................... 39 3.6 Sample Preparation.......................................................................................................39 3.6.1 Cylindrical Specim en:....................................................................................... 39 3.6.2 Beam Specimen:............................................................................................... 40 3.7 Tests on Fresh Concrete ................................................................................................ 40 3.8 Tests on Hardened Concrete .........................................................................................46 3.8.1 Compressive Strength....................................................................................... 46 3.8.2 Elastic Modulus Test ......................................................................................... 46 3.8.3 Flexural Strength Test ....................................................................................... 49 3.8.4 Splitting Tensile Strength Test ..........................................................................50 3.8.5 Free Shrinkage Test .......................................................................................... 53 3.8.6 Coefficient of Ther mal Expansion (CTE) Test................................................. 54 4 CONCRETE TEST RESULTS AND DISCUSSION ............................................................ 58 4.1 Introduction ................................................................................................................... 58 4.2 Analysis of Test Results and Discussion ......................................................................58 4.2.1 Compressive Strength Test Results................................................................... 58 4.2.1.1 Effect of RCA on com pressive strength............................................. 59 4.2.1.2 Effect of wa ter cement ratio on compressive strength........................ 59 4.2.2 Elastic m odulus Test Results............................................................................ 59 4.2.2.1 Effect of RCA on the elastic m odulus of concrete............................. 63 4.2.2.2 Effect of wa ter cement ratio on the elastic modulus of concrete........ 64 4.2.3 Flexural Strength Test R esults..........................................................................65 4.2.3.1 Effect of RCA on flexural strength ..................................................... 66 4.2.3.2 Effect of wa ter cement ratio on the flexural strength......................... 68 4.2.4 Splitting Tensile Strength Test Results .............................................................69 4.2.4.1 Effect of RCA on split ting tensile strength.........................................70 4.2.4.2 Effect of wa ter cement ratio on the splitting tensile strength............. 70 4.2.5 Free Shrinkage Test Results .............................................................................. 72 4.2.5.1 Effect of RCA on free shrinkage ........................................................ 73 4.2.5.2 Effect of wa ter cement ratio on the free shrinkage............................. 73

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8 4.2.6 Coefficient of Ther mal Expansion Test Results............................................... 75 4.2.6.1 Effects of RAP on coeffi cient of thermal expansion of concrete....... 76 4.2.6.2 Effect of wa ter cement ratio on the coefficient of thermal expansion............................................................................................ 76 4.3 Summ ary of Test Results..............................................................................................78 5 EVALUATION OF POTENTIAL PERFORMANCE OF CONCRETE CONTAINING RCA IN PAVEMENT ............................................................................................................ 79 5.1 Finite E lement Model Used to Perform Stress Analysis............................................... 79 5.2 Results of Stress Analysis using FEACONS I V Analysis............................................81 5.2.1 Effects of RCA on Stress-Strength Ra tio of Concrete Pavem ent with varying Water to Cement Ratio......................................................................... 85 5.2.2 Observation on Results of Stress Analysis ....................................................... 85 6 CONCLUSIONS AND RECOMME NDATIONS................................................................. 89 6.1 Conclusions ...................................................................................................................89 6.2 Recommendations ......................................................................................................... 89 APPENDIX A INPUT GUIDE FOR FEAC ONS IV PROGRAM ................................................................. 91 B LABORATORY TEST RESULTS....................................................................................... 98 LIST OF REFERENCES.............................................................................................................101 BIOGRAPHICAL SKETCH.......................................................................................................105

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9 LIST OF TABLES Table page 3-1 Concrete mixes containing RCA evaluated....................................................................... 31 3-2 Mix proportions for concrete containing RCA..................................................................32 3-3 Physical properties of Portland cement.............................................................................. 32 3-4 Chemical properties of Portland cement............................................................................ 32 3-5 Specific gravity and water ab sorption of virgin aggregates...............................................33 3-6 Results of Sieve analysis on the virgin aggregate.............................................................. 33 3-7 Specific gravity and water absorption of RCA.................................................................. 33 3-8 Results of Sieve analysis on RCA..................................................................................... 33 3-9 Tests performed on the concrete samples.......................................................................... 38 3-10 Standards for fresh concrete tests...................................................................................... 41 3-11 Properties of fresh concrete.............................................................................................. .41 4-1 Compressive strength test results....................................................................................... 58 4-2 Elastic modulus test results............................................................................................... .60 4-3 Flexural strength test results..............................................................................................66 4-4 Splitting tensile strength results......................................................................................... 69 4-5 Free shrinkage test results..................................................................................................73 5-1 Computed maximum stresses and stress-strength ratios in concrete pavem ent containing 0.43 w/c ratio....................................................................................................82 5-2. Computed maximum stresses and stress-st rength ratios in concrete pavement containing 0.48 w/c ratio....................................................................................................83 5-3 Computed maximum stresses and stress-strength ratios in concrete pavem ent containing 0.53 w/c ratio....................................................................................................84 A-1. Input guide for FE ACONS IV program............................................................................. 91 B-1 Results of compressive strength tests (psi) ........................................................................98

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10 B-2 Results of elastic modulus tests (x106psi).......................................................................... 98 B-3 Results of flexural strength tests (psi)................................................................................98 B-4 Results of splitting tens ile strength tests (psi).................................................................... 99 B-5 Results of free shrinkage tests (10-6 in/in).........................................................................99 B-6 Results of coefficient of thermal expansion tests (10-6 /oF)............................................. 100

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11 LIST OF FIGURES Figure page 3-1 Gradation chart for virgin aggregates................................................................................ 34 3-2 Gradation chart for RCA.................................................................................................... 34 3-3 Gradation chart for concre te m ixes containing 25%RCA................................................. 35 3-4 Gradation chart for concre te m ixes containing 50%RCA................................................. 35 3-5 Comparison of gradation for coarse aggregates................................................................. 36 3-6 Comparison of gradation for fine aggregates..................................................................... 36 3-5 Deleterious materials from stockpile of RCA .................................................................... 37 3-6 Separated coarse RCA.......................................................................................................37 3-7 Separated fine RCA...........................................................................................................38 3-8 Drum mix................................................................................................................... ........41 3-9 Scale...................................................................................................................... .............42 3-10 Cylinders on vibrating table.............................................................................................. .42 3-11 Beams covered with polythene sheets...............................................................................43 3-12 Vibration of beams.............................................................................................................43 3-13 Samples in moist curing room........................................................................................... 44 3-14 Determination of slump.................................................................................................... .44 3-15 Determination of unit weight............................................................................................. 45 3-16 Determination of air content.............................................................................................. 45 3-17 Material testing system 810 [Guang Li, 2004].................................................................. 47 3-18 Sample in compressive test................................................................................................48 3-19 Sample in modulus of elasticity test.................................................................................. 48 3-20 Flexural test setup..............................................................................................................51 3-21 Failure of sample under flexural test................................................................................. 51

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12 3-22 Splitting tensile setup.........................................................................................................52 3-23 Failed sample from splitting tensile test............................................................................ 52 3-24 Free shrinkage setup...................................................................................................... ....53 3-25 Coefficient of thermal expansion setup............................................................................. 56 3-26 Grinder................................................................................................................... ............56 3-27 Sawing machine............................................................................................................ .....57 4-1 Effect of RCA on compressive strength of 0.43 w/c ratio .................................................60 4-2 Effect of RCA on compressive strength of 0.48 w/c ratio .................................................61 4-3 Effect of RCA on compressive strength of 0.53 w/c ratio .................................................61 4-4 Effect of water cement ratio on compressive strength at 14days....................................... 62 4-5 Effect of water cement ratio on compressive strength at 28days....................................... 62 4-6 Effect of RCA on elastic modulus of 0.43 w/c ratio ..........................................................63 4-7 Effect of RCA on elastic modulus of 0.48 w/c ratio ..........................................................64 4-8 Effect of RCA on elastic modulus of 0.53 w/c ratio ..........................................................64 4-9 Effect of water cement ratio on elastic modulus at 14 days.............................................. 65 4-10 Effect of water cement ratio on elastic modulus at 28days............................................... 65 4-11 Effect of RCA on flexur al strength of 0.43 w/c ratio ........................................................ 67 4-12 Effect of RCA on flexur al strength of 0.48 w/c ratio ........................................................ 67 4-13 Effect of RCA on flexur al strength of 0.53 w/c ratio ........................................................ 68 4-14 Effect of water cement ratio on flexural strength at 14 days ............................................. 68 4-15 Effect of water cement ratio on flexural strength at 28 days ............................................. 69 4-16 Effect of RCA on splitting te nsile strength of 0.43 w/c ratio ............................................71 4-17 Effect of RCA on splitting te nsile strength of 0.48 w/c ratio ............................................71 4-18 Effect of RCA on splitting te nsile strength of 0.53 w/c ratio ............................................71 4-19 Effect of water cement ratio on splitting tensile strength at 14 days ................................. 72

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13 4-20 Effect of water cement ratio on splitting tensile strength at 28 days ................................. 72 4-21 Effect of RCA on free shrinkage of 0.43 w/c ratio............................................................ 74 4-22 Effect of RCA on free shrinkage of 0.48 w/c ratio............................................................ 74 4-23 Effect of RCA on free shrinkage of 0.53 w/c ratio............................................................ 74 4-24 Effect of water cement ratio on RCA at 28 days...............................................................75 4-25 Effect of RCA on coefficient of therm al expansion of 0.43 w/c ratio............................... 76 4-26 Effect of RCA on coefficient of therm al expansion of 0.48 w/c ratio............................... 77 4-27 Effect of RCA on coefficient of therm al expansion of 0.53 w/c ratio............................... 77 4-28 Effect of water cement ratio on coef ficient of therm al expansion at 28days..................... 77 5-1 Finite element model used in FEACONS IV analysis....................................................... 80 5-2 22-kip wheel load at sl ab corner and m iddle edge............................................................. 80 5-3 Example input file input us ed for the FEACONS IV program .......................................... 81 5-4 Effect of RCA on stress-strength ratios at the m iddle edge of slab with +20oF temperature differential for 0.43 water cement ratio......................................................... 86 5-5 Effect of RCA on stress-strength ratios at the m iddle edge of slab with +20oF temperature differential for 0.48 water cement ratio......................................................... 86 5-6 Effect of RCA on stress-strength ratios at the m iddle edge of slab with +20oF temperature differential for 0.53 water cement ratio......................................................... 87 5-7 Effect of RCA on stress-s treng th ratios at the corner edge of slab with -20oF temperature differential for 0.43 water cement ratio......................................................... 87 5-8 Effect of RCA on stress-strength ratios at th e corner edge of slab with -20oF temperature differential for 0.48 water cement ratio......................................................... 88 5-9 Effect of RCA on stress-strength ratios at th e corner edge of slab with -20oF temperature differential for 0.53 water cement ratio......................................................... 88 A-1 Example of number of nodes and elem ents.......................................................................97

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14 Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Engineering CONCRETE CONTAINING RECYCLED CONCRETE AGGREGATE FOR USE IN CONCRETE PAVEMENT By Patrick Amoah Bekoe August 2009 Chair: Mang Tia Major: Civil Engineering Our study evaluated the feasibility of usi ng concrete containing recycled concrete aggregate (RCA) in concrete pavement applic ation. Concrete containi ng 0%, 25% and 50% of RCA were produced in the laboratory and their properties vital to the performance of concrete pavement evaluated. Result from the laboratory te sting program indicates that the compressive strength and elastic modulus is re duced slightly as the percentage of RCA increases. The flexural strength, splitting tensile strength and coefficient of thermal e xpansion is about the same for concrete containing virgin aggregate and RCA. The free shrinkage increases slightly as the percentage of RCA increases. From the measur ed properties, a finite element analysis was performed to determine how the concretes c ontaining the different amounts of RCA would perform if they were used in a typical concrete pa vement in Florida. The analysis from the finite element model determined the maximum stresses under critical temperature and load conditions. The potential performance of the different pa vements was evaluated based on the computed maximum stress to the flexural strength ratio. The maximum stress to flexur al strength ratio in the pavement was found to be about the same as the percentage of RCA increases. This indicates that RCA can be used successfully in concrete pavement without affecting the performance.

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15 CHAPTER 1 INTRODUCTION 1.1 Background and Research Need The elastic modulus, Poissons ratio, coefficient of therm a l expansion and modulus of rupture are key material input required for critical response computation in the MechanisticEmpirical Design Guide of new and rehabilitated pavement structures. Concrete pavements using concrete with a lower modulus of elasticity wo uld have a lower stress due to the same applied load and thus could have a lower chance of cracki ng. In an investigation of the performance of I75 concrete pavements in Sarasota and Manate e counties, it was reported that the percent cracked slabs increased with an in crease in modulus of elasticity of the concrete [Tia et al. 1989]. In another research study on pavement concrete it was reported that the optimal concrete mixture for concrete pavement was not necessarily a concrete with a high flexural strength, but a concrete with a proper combina tion of low modulus of elasticity, low coefficient of thermal expansion and adequate flexur al strength [Tia et al. 1991]. Recycled concrete aggregates is currently be en used as a base material in flexible pavement construction but its use in a new rigi d pavement has not been fully exploited. Past research supported by the Florid a Department of Transportation (FDOT) has also been focused on the use of recycled concrete as base materi al for concrete and aspha lt pavement. With the increasing volume of waste or by-product materi als from industry, domestic and mining sources, decreasing availability of landfill space for disposal, depletion of virgin aggregates and the increasing cost of asphalt pavement, recycling ha s become an obvious choice not only as a base material for flexible pavement but also for new ri gid concrete pavements. Thus there is a need to assess the performance of recy cled aggregate concrete used for concrete pavement.

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16 1.2 Hypothesis of Research Incorporation of Recycled Concrete Aggregates (RCA) in c oncrete can reduce the m odulus of elasticity of concrete mixtur e and can reduce the load induced stresses in concrete pavements. RCA added to concrete mixtures reduce the flexur al strength only slightly. Addition of RCA to concrete can reduce the stress-s trength ratio and thus improve the performance of concrete pavement at critical temp erature and load condition. 1.3 Research Objectives The m ain research objectives of this study are as follows: 1. To evaluate the potential use of RCA in conc rete and its effects on the mechanical and thermal properties of concrete. 2. To assess the performance of concrete containi ng different amounts of RCA when used in a typical concrete pavement in Florida. 1.4 Research Approach The following approaches are used in this research: 1. Perform a literature review on past and present studies on the use of RCA in concrete. 2. Prepare concrete mixtures containing natura l aggregates and RCA ma terial with varying proportions. 3. Evaluate the properties of conc rete containing different amo unts of RCA in the laboratory. 4. Perform stress analyses on hypothetical conc rete pavements under critical load and temperature conditions in Florida, if these pavements were made with these concretes containing different amounts of RCA. Evaluate the potenti al performance of these hypothetical pavements based on the ratio of computed maximum stress to the flexural strength of the concrete

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17 CHAPTER 2 LITERATURE REVIEW 2.1 Introduction This Chapte r seeks to review some of the lit erature available on the subject of the history of recycling of concrete aggreg ates, production of recycled aggreg ate, the proper ties of RCA and concrete made from RCA. 2.2 Historical Overview of Concrete Recycling Recycling in the cons truction industry dates back seve ral centuries. The R omans are thought to be the first to develop recycling technology more than 1900 years ago. They built wall, roads and aqueducts with concrete using rock, and sometimes crushed burnt clay brick, as an aggregate [Schulz, 1988]. Recycling of concre te on a large scale bega n within Europe after the widespread destruction brought about by Worl d War II. In Germany, recycling became an important way of using debris created during war. Since rebuilding the transportation infrastructure was a top priority, Germany developed an early lead in the recycling of rubble into new highway construction products. For example, by 1987, some 100million tons of debris had been processed into aggregates and other produ cts in Berlin alone [Von Stein, 1993]. The first modern recorded use of concrete recycling occu rred in the U.S. in 1942 [Richardson and Jordan, 1994]. It was performed by the Portland Cement A ssociation and was used in the rehabilitation of failed road pavement in Kansas. The use of the recycled concrete became more common in the 1970s when the Army utilized it for runway construction. The Federal Highway Administration (FWHA) also began programs in recycling since the early 1970s. 2.3 Current Development in Concrete Recycling Since the year 2000, there has been a renewe d interest in recy cling, spurred by an increasing volum e of waste or by-product materi als from industry, domestic and mining sources

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18 and a decreasing availability of landfill space for disposal [M arcia et al, 2000]. In 2003, the FHWA undertook a National Review of Recycled C oncrete Aggregate use, and the results were published in September 2004. Its purpose was to capture, for technology transfer, the most advanced uses of recycled concrete aggregat e by state highway agenci es. The FHWA found that concrete routinely is being recy cled into the highways of the United States, and its principal application has been as ba se material [Kuennen, 2008]. The Construction Materials R ecycling Association maintains that 140 million tons of concrete are recycled in the United States. Ho wever, many economic factors impact the supply including equipment costs, transportation co sts and external landfill tipping fees. A major obstacle is the cost of crushing, grading, dust control and separation of undesirable constituent when using building rubble as aggregate for co ncrete. RCA from crushed concrete pavement and massive structures can prove to be an economical source of aggregate where good quality aggregates are scarce and when the cost of waste di sposal of concrete rubble is high [Mehta et al, 2006]. Aggregate producers need to contend with these factors before marking a decision to enter the recycle market. In 2005, United State Geological survey (USG S) reported the U.S average price of RCA as $7.62 per metric ton wh ich compares well with virgin stone of an average of $7.16 per metric ton. That the degree of penetration of RCA into a local market will depend on availability of demolition materials, its quality after processing local labor costs and local landfill tipping fees [Kuennen, 2007, Oct] The March 2007 issue of Rock Products reported on a Transportation Research Board paper that supported higher s ubstitution of RCA for virgin aggregates in large airf ield applications. Saeed [Saeed et al. 2007], of Applied Research Association Inc., reported in their paper, Comprehensive Ev aluation, Design and Construction Techniques for Airfield Recycled Concrete Aggr egate as Unbound Base, th at a small increase

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19 in the amount of recycled concrete aggregate to replace the virgin aggregate in pavement construction will have large econom ic and environmental benefits while extending the supply of traditional construction materials. A survey conducted of many highway agencies in the United States depicts that there is a great potential for the use of recycled aggreg ates in new pavement construction. There are sufficient published data currently available to de monstrate that RCA is a viable alternative to virgin aggregate for unbound base c ourse construction. In the State of Florida it is estimated that about 10% of the current aggregate requirement are produced from recycling .In 2001, FDOT undertook a study on the Use of recycled Concrete made with Florida lime stone aggregate for a base course in flexible pavement and the re port submitted by Kuo [Kuo et al. 2001], support the hypothesis that RCA can be used effectively as a base course when appropriate quality control techniques are utilized. Thus RCA from demolis hed materials is broadly accepted as a base material but its use as an aggregate in c oncrete itself has not been fully accepted. In 1983, deteriorated concrete from a 9 km (6 mi) long freeway pavement in Michigan was crushed, and the rubble was used as aggregate for concrete that was needed for the construction of the new pavement [Mehta et al. 2006, pp 264]. In 1986, the Illinois Department of Transportation (IDOT) undertook a demonstrati on project to monitor the construction and performance of two separate concrete pavement s constructed from an old recycled PCCP. On one project, an old, badly faulted, jointed reinforced concrete (JRC) pavement containing high quality aggregates was recycled into a new con tinuously reinforced concrete (CRC) inlay. On the second project, a deteriorated CRC pavement c ontaining D-cracking susceptible aggregates was recycled into a full-depth asphalt concrete (A C) inlay. Inlays were constructed because the existing shoulders were in good condition. The construction of both projects was monitored.

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20 Performance monitoring of the recycled pavement began in 1987, and included friction testing, ride quality testing, visual distress surveys, and deflection testing with a Falling Weight Deflectometer. After five to six years in servi ce, no major maintenance has been required and both pavements were performing well. RCA is not used in higher-quality applications often because of long-term performance considerations and because most professionals are hesitant to use a relatively untested material with no deve loped guidelines or specifications for its use [Wilburn and Goonan 1998]. Moreover, the reuse of crushed concrete as a ggregate in high-grade concrete has up to now been restricted by a lack of standards, experience, and knowledge. It would require extensive screening and testing of the recycled material to produce recycled coarse aggregate that would potentially m eet the technical specifications and performance expectations for structural Portland cement c oncrete. However, laboratory research and experience at several recent projects have proven that it is feasible to use recycled concrete as aggregate for new concrete mixtures. The use of recycled fine a ggregate is however mostly unsuitable due to the large amount of hydrated cement and gypsum. Speci fications often vary considerably by local climatic conditions and product avai lability because the quality of the recycled materials varies from location to location and is fa irly difficult to contro l The above studies suggest that there is technical feasibility in the use of recycled old PCCP as aggregates for new PCCP. 2.4 General Properties of RCA from Concrete Pavement 2.4.1 Production of Recycled Concrete Aggregates Recycled C oncrete Aggregates (RCA) from ex isting concrete pavements or other concrete structures involves the demolition of the existing structure, removal of broken concrete and transporting to the crusher, removal of steel if any, crushing, sizing and stockpiling of the aggregates. The breaking up procedure used depe nds on a number of factors key amongst them are the location, the condition of the existing pavement, and traffic. This is done to reduce the

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21 concrete into smaller sizes in order for it to be easily transported. Most commonly used demolishing equipments are hand operated power tools, vehicle-mounted equipments and the hydro demolition. The removal of the broken concre te and transporting to the crusher involves the use of various equipments key amongst them are backhoes/hydraulic excavators, Loaders/front-end loaders and truc ks/dump trucks. Crushing is usually performed in two steps: a primary crusher reduces the larg er incoming debris, and a secondary crusher further reduces the material to the desired particle size. Magnetic ferrous metal rec overy can take place after both stages. The two main types of equipment are ja w and impact crushers. Jaw crushers are best suited to reduce large or odd-shaped debris quickl y from construction and demolished projects to a manageable size. Impact crushers are more effe ctive than jaw crushers at freeing rebar encased in rubble. At the crushing plant, all steel re inforcement or wire mesh are removed and the aggregates are sized to the desi red sizes and stockpiled. The pro cessed RCA typically consists of 60% to 75% high-quality, well graded aggregates th at are held together by the hardened cement paste [Kuo et al. 2001]. The amount of cement paste that remains attached to aggregate particles in RCP after processing depends on the process used to manufacture RCP and properties of the original concrete. Cement paste attached to aggregate particles in RCP makes RCP less heavy than conventional aggregate [Saeed et al. 2007]. 2.4.2 Physical and Mechanical Properties of Coarse Recycled Aggregates Recycled coarse aggregates have attached m ortar which influences its physical and mechanical properties in both fresh and hardened concrete. The physical properties of recycled aggregates depend on both adhere d mortar quality and the am ount of adhered mortar. The crushing procedure and the dimension of the recy cled aggregate have an influence on the amount of adhered mortar [Hansen, 1986]. The adhered mortar is a porous material; its porosity depends upon the w/c ratio of the recycled concrete em ployed [Nagataki, 2000]. The absorption capacity

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22 is one of the most significant properties whic h distinguish recycled aggregate from raw aggregates, and it can have an influence both on fresh and hardened concrete properties. Compared to virgin coarse a ggregate, recycled coarse aggr egates are highly angular in shape and have a rougher surface texture, lower specific gravity, and higher water absorption. Furthermore, Recycled Aggregates are more permeable than most natural sands, crushed limestone and gravel [Chesner et al.1998]. Genera lly, up to 30% of the co nventional aggregate in concrete may be replaced by recycled aggregate without significantly a ffecting the mechanical properties of the new concrete. This may be the simplest, most economical, and least controversial way of getting wider use of recycled aggregates in new concrete [ECCO, 2003]. 2.4.3 Gradation The gradation of aggregates refers to th e particle size distribution. The gradation inf luences mainly the workability and the cost of the concrete. Specifica tions for the gradation are normally based on the gradation limits and the maximum aggregate size. As any aggregate used for concrete, RCA must meet the grada tion requirements, it must be strong, posses good dimensional stability and provide acceptable workability. Moreover, RCA must be inert and free from potential harmful impurities that affect the e nvironment. Most research into recycled coarse aggregates show that they meet ASTM C 33 specification for coarse aggregates. 2.4.4 Particle Shape and Texture The shape and textu re of aggregates particle s influences mainly the properties of fresh concrete more than hardened concrete. Co mpared to smooth and rounded particles, roughtextured, angular and elongated particles require more cement paste to produce workable concrete mixtures. Surface textur e refers to the degree to which the aggregates surface is smooth or rough and is based on visual judgment [Mehta et al, 2006, pp 276]. Surface texture depends on the hardness, grain size, and porosit y of the parent rock and its s ubsequent exposure to forces of

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23 attrition. Demolished plain and reinforced concrete can be crushed in various types of crushers to provide recycled aggregate with an acceptable pa rticle shape, but the t ype of crushing equipment influences the gradation and othe r characteristics of crushed c oncrete fines. Compared with natural aggregates, the surface te xture and shape of recycled aggregates are generally rough, porous and highly angular. This is attributed to the presence of the old mortar. Typically 30% to 60% by volume of old mortar is adhered to recycl ed coarse aggregate particles, depending on the aggregate size. More old mortar is attached to the smaller size fractions of coarse aggregate [ECCO, 2003]. 2.4.5 Specific Gravity Due to the large am ount of old mortar and cem ent paste adhered to recycled aggregates, their specific gravity (relative dens ity) is 5% to 10% lower than th at of the virgin aggregates in old concrete. Typical values of specific gravity of recycled aggregates range between 2.2 and 2.5 in the saturated surface dry condition. [ECCO, 2003]& [Saeed et al. 2007] 2.4.6 Density In general recycled agg regates have densit ies slightly lower than virgin aggregates. Hansen [Hansen, 1986] and the Building Contractors Society of Japan (1978) attributed this to the low density of attached cement mortar to the aggregates. Variations in water-cement ratios of the concrete did not significantly affect the densities [Hansen, 1986]. 2.4.7 Water Absorption Water absorption of recy cled aggregates happens to be one of the major property differences between recycled and virgin aggregates. The Building Contractors Society of Japan (1978) and Hansen [Hansen, 1986] concluded that the higher wa ter absorption of the coarse aggregates is a result of the absorption of the old cement mortar attached to the aggregate particles. NHRP Report 598 (2007) ga ve typical water absorption of recycled coarse aggregates

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24 in the United States to be between 2% to 6%. Absorption rates for crushe d concrete fines range from 4% to 8%. Pre-soaking of recycled aggregat es is sometimes recommended to help maintain uniformity. 2.4.8 Los Angeles Abrasion Loss The abras ion resistance of aggregates is very important in concrete pavements. ASTM C 33 indicates that aggregates for use in concrete construction should have abrasion loss of less than 50% for general construction and for cr ushed stone used under pavements should have losses less than 40%. [Hansen,1986] concluded based on data available that recycled concrete aggregates produced from all but the poorest quality recycled concrete can be expected to pass ASTM requirements for concrete aggregates. NHRP Report 598 (2007) gave typical LA abrasion Loss for recycled coarse aggregates in th e United States to be between 20% to 45%. 2.4.9 Sulfate Soundness Sulfate soundness tests (ASTM C 88) are requi red by ASTM C 33 and recycled concrete fine and coarse aggregates m ay be tested by ASTM C 88 to ensure that appropriate resistance to freezing and thawing of the recycled aggreg ates. NHRP Report 598 (2007) gave typical Magnesium Sulfate Loss for recycled coarse aggreg ates in the United States to be less than 9%. 2.5 Properties of Concrete made from RCA 2.5.1 Fresh Concrete 2.5.1.1 Mix design The principles used to design concrete m ixtures with conventional aggregates apply to using recycled aggregates with additional care. Trial mixtures are required to determine proper proportions and to check new concretes qualit y. Hansen [Hansen, 1986] recommended that all recycled concrete aggregates are pre-soaked to offset the high absorption before mixing.

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25 2.5.1.2 Water cement ratio Selection of the w/c is the most critical part of controlling the concrete strength. There is excellent correlation between w/c and compressive and flexural strength. Hansen concluded that the w/c is valid for recycled aggregate concrete as it is for concrete made with virgin materials, but only the level of strengt h development would be redu ced [Hansen 1986]. To produce a similar workability, Mukail [Mukai et al. 1979] f ound that 5% more water was required for a recycled coarse aggregate concrete. Buck [Buc k, 1976] has found that approximately 15% more water was needed to produce the same workability for both fine and coarse recycled aggregate concrete. Mukail [Mukai et al. 1979] and Hansen and Narud [Hansen and Narud,1983] found that bleeding from recycled aggregate concrete to be slightly less than that of those using virgin aggregates. 2.5.1.2 Unit weight and air content Mukail [Mukai et al. 1979] and Hansen and Narud [Hansen and Narud,1983] concluded that unit weights of concrete m ade using recycled concrete as aggregate were within 85%to 95% and 95%, respectively, of the original concrete mixture. Mukail [Mukai et al. 1979] found that air contents of freshly recycled concrete were hi gher and varied more than air contents of fresh control mixtures. Hansen and Narud [Hansen and Narud, 1983] found that air contents of recycled aggregate concrete were up to 0.6% higher. Hansen [Hansen, 1986] concluded that the air contents of recycled aggregate concrete were slightly higher and that densities can be 5% to 15% lower. 2.5.1.3 Fine to coarse aggregate ratio From the point of view of both economy and cohesion of fresh concrete, Building Contractors Society of Japan (1978) found that the optimum ratio of fine-to-coarse aggregate is the same for recycled aggregate concrete as it is for concrete made from virgin materials

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26 [Hansen, 1986]. Studies by Kasai [Kasai, 1985] indicat e that the fineness of recycled concrete aggregates decreases with time of mixing. This is most likely a re sult of mechanical removal of cement paste from the recycled coarse aggregates. 2.5.2 Hardened Concrete 2.5.2.1 Compressive strength A num ber of studies have investigated the strengths of concrete made with recycled aggregates. Most found reductions in streng ths from approximately 5% to 24% using recycled aggregates [Hansen, 1986]. Hansen and Narud [Hansen and Narud, 1983] found that recycled aggregate concrete obtained approximately the same strengths as the original concrete from they were made. Bernier [Bernier et al. 1978] found similar results, ex cept that in the case of highstrength concrete produced from low-strength re cycled coarse aggregates, they found that the compressive strength was 39% lower than the high-strength concrete produced from highstrength recycled aggregates. Hansen and Narud [Hansen and Narud, 1983]concluded that the compressive strength of recycled concrete depend s on the strength of the or iginal concrete and it is largely controlled by a combination of the wa ter-cement ratio (w/c) of the original concrete and the w/c of the recycled concrete. Reports by Hansen and Narud [Hansen and Narud, 1983] and Buck [Buck, 1976] concluded that higher stre ngth concrete could be made from recycled aggregates from lower-strength concrete. Concrete manufactured from both coarse and fine recycled aggregates has been investigated. The majority of researchers found that the compressive strengths for concrete manufactured from recycled coarse and fine a ggregates were lower by 15 % to 40% of strengths of concrete made with all naturally occurring materials. Rasheeduzzafar [Rasheeduzzafar, 1984] found that the low strength and corresponding high water absorption for recycled concrete could be offset by lowering the w/c of th e recycled concrete by 0.05 to 0.10

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27 Blends of 50% natural and 50% recycled sa nds produced strengths 10% to 20% less than recycled concrete made with al l natural sands. Further examina tion reveals that certain portions of the fine recycled aggregates appear to inhibi t recycled concrete perfor mance. Studies indicate that the majority of strength loss is brought about by that portion of the recycled aggregate smaller than 2 mm. Therefore, the use of any recycled fines in concrete production may be prohibited [Hansen,1986]. 2.5.2.2 Tensile and flexural strength Various researchers have invest igated the effect of recycled aggregates on flexural and tensile strengths. The majority of findings indica te that concrete made from recycled coarse aggregates and natural fine aggregates has gene rally the same or, at most, a 10% reduction in tensile strength. Generally, conc rete made from recycled coar se and fine aggregates has reductions in tensile strengths of less than 10% and a maximum of 20% reduction for the worst case [Hansen,1986]. 2.5.2.3 Elastic modulus Building Contractors Society of Japan (1978) investigated the change in modulus of elasticity of concrete m ade using recycled concrete aggregates. Th ey reported that the reductions in modulus of elasticity made w ith recycled coarse and fine aggr egates varied from 25% to 40%. They also reported that the reductions in modul us of concrete made with recycled coarse aggregates varied only from 10% to 33%. 2.5.2.4 Drying shrinkage Concrete m ade with recycled coarse aggregates and natural sands produced shrinkages of 20% to 50% greater than concrete made with all natural aggr egates Building Contractors Society of Japan (1978). Concrete made with recycled coarse and fine aggreg ates produced shrinkages that are 70% to 100% greater than that of co rresponding natural aggregates Building Contractors

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28 Society of Japan (1978). Hansen [Hansen, 1986] found that shrinkages were greater for higherstrength concrete than for lower strength concre te. The increase in the drying shrinkage may be due to the combined effects of lower modulus of elasticity of the aggregates and additional shrinkage caused by mortar adhering to aggregat es [Sri Ravindrarajah et al.1985]. Thus from shrinkage point of view, the use of recycled aggr egates is undesirable. However it is possible to reduce the shrinkage by making modi fications to the mix design. 2.5.2.5 Coefficient of thermal expansion Coefficient of therm al expansion (CTE) is a key property of concre te that control the amount of expansion/contraction due to changes in temperature. Coefficient of thermal expansion of a mix mainly depends on the aggreg ate type and the amount of aggregate in a mix. Limestone is known to have the lowest coefficients of thermal expansion compared to rocks such as sandstone and granite. A research by Smith et all (2009) on concre te containing 0%, 15%, 30%, and 50% of coarse RCA showed that as the coarse RCA content increased the CTE decreased. 2.5.2.6 Creep Hansen (1986) found that creep for concrete m anufactured from recycled aggregates to be 30% to 60% greater than conc rete manufactured from virgin ma terials. These results are not surprising because concrete containing recycled aggregates has up to 50% more paste volume, and creep of concrete is proportiona l to the content of paste or mortar in concrete [Lamond et al. 2001]. 2.5.2.7 Permeability Concrete m ade from recycled aggregates W/C of 0.5 to 0.7, has permeability two to five times that of concrete made with natural aggregates [Hansen 1986].

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29 2.5.2.8 Freeze and thawing resistance Many studies of freezing -and-thawing resistance indicate that there is almost no difference between that of concrete made with virgin aggregates and with recycled aggregates [Hansen, 1986]. A report by the Building Contractors Societ y of Japan (1978), however, indicated that concrete made from recycled coarse and fine aggregates had significantly reduced resistance to freezing-and-thawing damage. They also found that if the fine aggregates were replaced with virgin materials, the freezing-and-thawing resist ance was comparable to the original concrete. Another Japanese study indicated th at air entrained concrete made with recycled aggregates has less freezing-and-thawing resistance than the concre te made with virgin materials [Hasaba et al. 1981]. 2.5.2.9 Carbonation, chloride penetr ation and reinforcement corrosion The Building Contractors Society of Japan (1978 ) concluded that the rate of carbonation of a recycled aggregate concrete made with concrete that had already suffered carbonation was 65% higher than the control concrete made with c onventional aggregates. Th e Building Contractors Society of Japan also concluded th at reinforcement in recycled c oncrete may corrode faster than in conventional concrete. This accelerated corrosion, however, could be offset by reducing the w/c of the recycled concrete. Additional st udies by Rasheeduzzafar [Rasheeduzzafar, 1984] confirmed these conclusions. Hansen [Hansen, 1986] also concluded th at a reduction in w/c reduces corrosion potential of recycled concrete.

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30 CHAPTER 3 MATERIALS AND TEST METHODS 3.1 Introduction This chapter deals with details of m ix proportion and mix ingredients used for the concrete mixtures in this research. It also explains the standard method and fabrication procedure for the preparation of concrete mixture in laboratory and the standard ASTM testing methods performed in this research study. 3.2 Concrete Mix Proportions The percentages of RCA incorporated in the different concrete m ixtures evaluated are shown in Table 3-1. The mix proportions for thes e different mixtures are shown in Table 3-2. 3.3 Mix Ingredients The properties of the ingredients used for the m ix are below Water : Water supplied from the city of Gaines ville grid was used for the mix. It was ensured that no foreign impurities got into the water. Cement : Portland cement type I/II supplied by Florida Rock Industry was used. Table3-3and Table 3-4 shows the physical and chemical properties of the cement determined by Florida Department of Transportation. Virgin Aggregates : Silica sand from Goldhead of Florid a was used as fine aggregate and number 57 Miami Oolite limestone was used as co arse aggregate. Physic al properties of this aggregate were obtained by Florida Department of Transportation pe rsonnel. The results of these properties for fine and coarse aggregate are s hown in Table 3-5 and Ta ble 3-6. Figure 3-1 shows the gradation chart for the fine and coarse aggregate. Recycled Concrete Aggregates (RCA): RCA was obtained from the stockpile of Kimmins Construction Corporation in Tampa. The RCA contained deleterious materials such as

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31 wood, plastics, metals and glass. These materials were hand picked from the stockpile during and after sieving. Figure 3-5 shows some of the de leterious materials removed from the RCA. The material was separated into coarse and fine portio ns using a #4 sieve. Figure 3-6 and Figure 3-7 shows respectively coarse and fine the material s which have been separated by a mechanical shaker. Tests were run on the RCA to determ ine their specific gr avity, water absorption, gradation and LA abrasion Loss. The results of sieve analysis on RCA material are shown in Table 3-8 and Figure 3-2 shows th e Gradation. Results of specifi c gravity water absorption and LA abrasion Loss of RCA mate rials are shown in Table 3-7. Combined gradation curve: Figures 3-3 to 3-4 shows the combined gradation curve of the virgin and recycled aggregates based on the concrete mixtures containing different percentages of RCA. A comparison of the gradation for coarse and fine aggregate containing different amount of RCA is also shown in figures 3-5 to 3-6. Table 3-1. Concrete mixes containing RCA evaluated Mix Number W/C Ratio Cement Content (lb/cy) Virgin Coarse Aggregates (%) Coarse RCA (%) Virgin Fine Aggregate Fine RCA (%) Total RCA (%) 1 0.43 628 100 0 100 0 0 2 0.43 628 75 25 75 25 25 Set 1 3 0.43 628 50 50 50 50 50 1 0.48 563 100 0 100 0 0 2 0.48 563 75 25 75 25 25 Set-2 3 0.48 563 50 50 50 50 50 1 0.53 508 100 0 100 0 0 2 0.53 508 75 25 75 25 25 Set-3 3 0.53 508 50 50 50 50 50 (Note: Coarse aggregate and coarse RCA are vol ume percent by total coarse aggregate, fine aggregate and fine RCA are volume percent by to tal fine aggregate. Total RCA is the total percentage replacement of coarse RCA and fine RCA)

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32 Table 3-2. Mix proportions fo r concrete containing RCA Mix Number W/C Ratio Cement Content (lb/cy) Water Content (lb/cy) Virgin Coarse Aggrega tes (lb/cy) Virgin Fine Aggrega te (lb/cy) Coarse RCA (lb/cy) Fine RCA (lb/cy) 1 0.43 628 270 1726 1198 0 0 2 0.43 628 270 1294 898 426 266 Set 1 3 0.43 628 270 863 599 853 531 1 0.48 563 270 1755 1219 0 0 2 0.48 563 270 1316 914 434 270 Set-2 3 0.48 563 270 878 610 876 540 1 0.53 508 270 1781 1237 0 0 2 0.53 508 270 1335 927 440 275 Set-3 3 0.53 508 270 891 619 879 549 Table 3-3. Physical properties of Portland cement Test Standard Specification Cement Loss on Ignition ASTM C114 2.6% Loss on Ignition (Acid Insoluble) ASTM C114 0.08% 7-Day Compressive Strength ASTM C109 4880 psi Time of Setting (Initial) ASTM 266 101 min Time of Setting (Final) ASTM 266 200 min Table 3-4. Chemical properties of Portland cement Constituents Percentage Aluminum Oxide 5.0% Ferric Oxide 4.2% Magnesium Oxide 0.7% Sulfur Trioxide 3.1% Tricalcium Aluminate 6.0% Tricalcuim Silicate 69.0% Total alkali as Na2O 0.41%

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33 Table 3-5. Specific gravity and water absorption of virgin aggregates Coarse Aggregates Fine Aggregates SSD Specific Gravity 2.37 2.64 Dry Bulk Specific Gravity 2.30 2.63 Dry Apparent Specific Gravity 2.53 2.65 Absorption 4.0 0.4 LA Abrasion Loss 37 / Table 3-6. Results of Sieve analysis on the virgin aggregate Sieve Size Sieve Size ( mm) Percentage Passing Coarse Aggregates Percentage Passing Fine Aggregates 1.5 37.0 100 / 1 25.0 100 / 12.5 50 / #4 4.75 7 100 #8 2.36 4 98 #16 1.18 / 87 #30 0.60 / 64 #50 0.30 / 35 #100 0.15 / 7 Fineness Modulus 2.09 Table 3-7. Specific gravity a nd water absorption of RCA Coarse RCA Fine RCA SSD Specific Gravity 2.34 2.34 Dry Bulk Specific Gravity 2.19 2.19 Dry Apparent Specific Gravity 2.58 2.56 Absorption 6.93 6.46 LA Abrasion Loss 49 / Table 3-8. Results of Sieve analysis on RCA Sieve Size Sieve Size ( mm) Percentage Passing Coarse Aggregates Percentage Passing Fine Aggregates 1.5 37.0 100 / 1 25.0 96 / 12.5 60 / #4 4.75 10 98.7 #8 2.36 4.0 88.5 #16 1.18 / 69.8 #30 0.60 / 51.6 #50 0.30 / 33.9 #100 0.15 / 20.6 Fineness Modulus 2.40

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34 Sieve SizePercentage Passing 0 10 20 30 40 50 60 70 80 90 100 110 1.5" 1" 1/2" #4 #8 #16 #30 #50 #100 Fine Aggregate Coarse Aggregate Figure 3-1. Gradation chart for virgin aggregates Sieve SizePercentage Passing 0 10 20 30 40 50 60 70 80 90 100 110 1.5" 1" 1/2" #4 #8 #16 #30 #50 #100 Fine RCA Coarse RCA Figure 3-2. Gradation chart for RCA

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35 Sieve SizePercentage Passing 0 10 20 30 40 50 60 70 80 90 100 110 1.5" 1" 1/2" #4 #8 #16 #30 #50 #100 Combined fine RCA Combined coarse RCA Figure 3-3. Gradation chart for c oncrete mixes containing 25%RCA Sieve SizePercentage Passing 0 10 20 30 40 50 60 70 80 90 100 110 1.5" 1" 1/2" #4 #8 #16 #30 #50 #100 Combined fine RCA Combined coarse RCA Figure 3-4. Gradation chart for c oncrete mixes containing 50%RCA

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36 Sieve SizePercentage Passing 0 10 20 30 40 50 60 70 80 90 100 110 1.5" 1" 1/2" #4 #8 #16 #30 #50 #100 Coarse 25% RCA Virgin RCA 50% RCA Figure 3-5. Comparison of grada tion for coarse aggregates Sieve SizePercentage Passing 0 10 20 30 40 50 60 70 80 90 100 110 #4 #8 #16 #30 #50 #100 Fine Virgin 25% RCA RCA 50% RCA Figure 3-6. Comparison of gradation for fine aggregates

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37 Figure 3-5. Deleterious material s from stockpile of RCA Figure 3-6. Separated coarse RCA

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38 Figure 3-7. Separated fine RCA 3.4 Fabrication and Curing of Concrete Specimen Concrete m ixtures were produced in the labora tory using a nine cubic feet drum mixer as shown in Figure 3-8. For each concrete mix, about seven cubic feet of fresh concrete was produced to fabricate twelve cyli nders (6" 12"), six cylinders (4 8"), six beams (6" 6" 22") and three prisms (3" 3" 11.25"). Tabl e 3-9 shows the details of tests performed on concrete samples with various sp ecimen sizes and curing periods. Table 3-9. Tests performed on the concrete samples Test Specimen Size Curing Period Compressive Strength 6" x 12" Cylinder 14 and 28 days Elastic Modulus 6" x 12" Cylinder 14 and 28 days Flexural Strength 6" x 6" x 22" Beam 14 and 28 days Splitting Tensile Strength 6" x 12" Cylinder 14 and 28 days Coefficient of Thermal Expansion 4" x 8" Cylinder 28 days Drying Shrinkage 3" 3" 11.25" Prism 28 days

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39 3.5 Concrete Preparation The following steps were followed to produce concrete in the laboratory; 1. Fill c loth bags with virgin and RCA fine aggregates required for mix. 2. Dry the fine aggregates for at least 24 hours in an oven at 23 0 F, and then let it cool for another 24 hours. 3. Fill jute bags with virgin and RCA co arse aggregates required for the mix. 4. Soak the coarse aggregates material for at l east 48 hours and remove it from the water for at least 45 minutes before weighing. 5. Based on the mix design, batch the virgin coarse aggregate, virgin fine aggregate, coarse RCA, fine RCA, cement and water using a weighing scale as shown in Figure 3-9. 6. Place the coarse aggregate, fine aggregate, co arse RAP and fine RAP in a drum mixer. 7. Run the mixer for 30 seconds 8. Add more than half of the mixing water and mix it for 1 minute 9. Place cement and mix it for 3 minutes, followed by a 2 minute rest, followed by a 3 minute mixing. 10. Perform fresh concrete property te sts as presented in Section 3.7 3.6 Sample Preparation After concrete was produced, som e portion of th e concrete was immediately used for conducting tests to determine fresh concrete properties as discussed in Section 3.7. The remaining concrete was used to fabricate different samples as follows: 3.6.1 Cylindrical Specimen: 1. Place conc rete in molds such that they are half filled. 2. Place the molds on a vibrating table and vi brate for 45 seconds. Then fill the molds completely and vibrate it for another 45 s econds. Figure 3-13 shows the cylinders on the vibratory table. 3. Finish the concrete surface with a hand trowel.

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40 4. Cover the concrete with plastic caps. 5. Remove the samples from the molds after 24 hours and place them in a moist curing room as shown in Figure 3-13. 3.6.2 Beam Specimen: 1. Place conc rete in molds such that they are half filled. 2. Vibrated with a hand equipped internal vibrator as shown in Figure 3-12 3. Finish the concrete surface with a hand trowel. 4. Cover the concrete with polythene sheets as shown in Figure 3-11. 5. Remove the samples from the molds after 24 hours and place them in a moist curing room as shown in Figure 3-13. 3.7 Tests on Fresh Concrete Table 3-13 provides the list of ASTM standard tests perform ed on the fresh concrete used in this study. The properties of the fresh conc rete mixtures are pres ented in Table 3-11. Slump Test: The test was run in accordance with ASTM C143. The slump is very useful in detecting variations in the uniformity of a mix of given nom inal proportions; it is a measure of consistency of the fresh concrete. This test is conducted immediately after the concrete has been made. Fig 3-14 shows a typical dete rmination of slump after mixing Unit Weight Test: The test was used to verify the dens ity of concrete mixtures as per the procedures of ASTM C138 standard. The theore tical unit weight was calculated and compared with the laboratory unit weight to determin e whether the mix was properly batched. Fig 3-15 shows a typical determination of unit weight after mixing Air Content Test: The entrapped air in the conc rete mix was determined by the pressure method in accordance with ASTM C231 test procedure. The Pressure meter was used for this test and an aggregate correction factor determined for each mix. Fig 3-16 shows a typical determination of air content after mixing

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41 Temperature Test: This test was run in accordance with ASTM C1064 test procedure to measures the temperature of freshly mixed concrete. Table 3-10. Standards for fresh concrete tests Test Standard Slump ASTM C143 Unit Weight ASTM C138 Air Content ASTM C173 Temperature ASTM C1064 Table 3-11. Properties of fresh concrete Mix Number W/C Ratio Cement (lb/cy) Water (lb/cy) Slump (in) Unit Weight (lbs/ft3) Air Content (Percent) Temperature (oF) 1 0.43 628 270 1.00 142 2.0 78 2 0.43 628 270 1.00 141 2.0 78 Set-1 3 0.43 628 270 1.00 140 1.2 79 1 0.48 563 270 1.50 142 2.0 78 2 0.48 563 270 1.00 141 2.0 78 Set-2 3 0.48 563 270 1.00 139 1.3 80 1 0.53 508 270 1.50 141 2.0 77 2 0.53 508 270 3.25 140 1.6 78 Set-3 3 0.53 508 270 1.75 139 1.4 81 Figure 3-8. Drum mix

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42 Figure 3-9. Scale Figure 3-10. Cylinders on vibrating table

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43 Figure 3-11. Beams covered with polythene sheets Figure 3-12. Vibration of beams

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44 Figure 3-13. Samples in moist curing room Figure 3-14. Determination of slump

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45 Figure 3-15. Determination of unit weight Figure 3-16. Determination of air content

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46 3.8 Tests on Hardened Concrete 3.8.1 Compressive Strength The standard ASTM C39 test procedure was fo llowed in running the compressive strength on the 6" 12" cylindrical specim ens. The ends of the specimen were gri nded before testing to ensure even loading during test. Figure 3-26 shows the grinder that was used. The diameter of each specimen was taken before placing it in an MTS 810 material testing system as shown in Figure 3-17 and Figure 3-18. The testing machin e was hydraulic controlled with a maximum capacity of 220kips. Load was applied to the specimen at a constant loading rate of 35 psi/s until complete failure occurred. The outputs of the load cell from the testing machine were connected to a data acquisition system, which records th e data during the test. The maximum load is recorded and the compressive stress computed by dividing the maximum load by the cross sectional area of the specimen. The type of fracture was also recorded. 3.8.2 Elastic Modulus Test The standard ASTM C469 test procedure was fo llowed in running the elastic m odulus test on the 6" 12" cylindrical specimens. The ends of the specimen were gri nded before testing to ensure even loading during test. Two 4-inch displacement gages, held by four springs were mounted on the sides of the specimen. The speci men was then placed in a MTS 810 material testing system as shown in Figure 3-17and Figure 3-18. The testing machine was hydraulic controlled with a maximum capacity of 220 kips. Lo ad was applied to the specimen at a constant loading rate of 35 psi/s until 40% of the maximu m load obtained from the compressive strength test is attained. The outputs of the displacement gages and the lo ad cell from the testing machine were connected to a data acquisition system, whic h records the data during the test. The average displacement reading was used to calculate the stra in, and reading from the load cell was used to calculate the stress.

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47 The modulus of elasticity was calculated as follows: )000050.0( 1 )(2 12 SSE where E = Chord modulus of elasticity, psi S2 = Stress corresponding to 40% of ultimate load S1 = Stress corresponding to a longitudinal strain, 1, of 50 millionths, psi and 2 = Longitudinal strain produced by stress S2 Figure 3-17. Material testi ng system 810 [Guang Li, 2004]

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48 Figure 3-18. Sample in compressive test Figure 3-19. Sample in m odulus of elasticity test

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49 3.8.3 Flexural Strength Test The flexural strength test wa s run in accordance with ASTM C78 on 6" 6" 22" beam specimen at each age and the average strength was computed. Before testing, the two loading surfaces were grounded evenly by using a grinding stone to ensure that the applied load was uniform. The flexural stre ngth was calculated according to the type of fracture in the beam as follows: 1. If the fracture initiates in th e tension surface within the middle third of the span length, calculate the modulus of rupture as follows 2bd PL R Where R = modulus of rupture, psi P = maximum applied load indicated by the testing machine, lbf L = span length, in, or mm, b = average depth of specimen, in, or mm, at the fracture, and d = average depth of specimen, in, or mm, at the fracture. 2. If the fracture occurs in the tension surface outside of the middle third of the span length by not more than 5% of the span length, cal culate the modulus of rupture as follows 23 bd Pa R Where R = modulus of rupture in psi P = maximum applied load indicated by the testing machine in lbf

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50 a = average distance between line of fractur e and the nearest support measured on the tension surface of the beam, in, or mm. b = average depth of specimen, in, or mm, at the fracture, and d = average depth of specimen, in, or mm, at the fracture. 3. If the fracture occurs in the tension surface outside of the middle third span length by more than 5% of the span length, discard the results of the test. 3.8.4 Splitting Tensile Strength Test The splitting tensile strength of concrete was run in accordance with ASTM C496 on cylindrical specimens (6 12). Four lines were drawn along the centre of the cylinder to mark the edges of the loaded plane and to help align the test specimen before the application of load. Figure 3-22 shows a typical setup of the cylinder during testing. A strip of wood, 3mm thick and 25mm wide, was inserted between the cylinder and the platens; this helped the applied force to be uniformly distributed. Load was applied and in creased until failure by i ndirect tension in the form of splitting along vertical diameter took place. The splitting tensile strength of a cylinder specimen was calculated using the following equation: LD P T2 Where T = splitting tensile strength of cylinder in psi, P = Maximum applied load in lbf, L = Length of cylinder in inch, D = Diameter of cylinder in inch.

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51 Figure 3-20. Flexural test setup Figure 3-21. Failure of sa mple under flexural test

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52 Figure 3-22. Splitting tensile setup Figure 3-23. Failed sample from splitting tensile test

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53 3.8.5 Free Shrinkage Test The free shrinkage measurement was made in accordance with ASTM C157 using 3 X 3X 11.25 square prism specimens. Figure 3-24 s hows a mold used to cast the sample. Steel end plates with a hole at their centers were us ed to install gage studs at both ends of the specimen. The specimens were removed from the molds at an age of 23 h (after the addition of water to cement during the mixing operation) and th en placed in lime-saturated water which was Figure 3-24. Free shrinkage setup

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54 maintained at 73.4 1 F (23.0 0.5C) for a minimum of 30 min. At an age of 24 h, the specimens were removed from water storage one at a time, and wiped with a damp cloth. An initial reading was immediately taken with a leng th comparator. The specimens were then stored in the drying room and comparator readings we re taken of each specimen after 28 days. Figure 3-24 shows the test set-up of the free shrinkage te st. The length change of a specimen at any age after the initial comparator r eading was calculated as follows: 100 G CRD initial CRD x Lx Where Lx =Length change of specimen at any age, %, CRD = Difference between the comparator reading of the specimen and the reference bar, G = gage length. 3.8.6 Coefficient of Thermal Expansion (CTE) Test The CTE test was run in accordance with AAS HTO TP60. The test set-up is shown in Figure 3-25. The samples were sawed using a sa wing machine as shown in Figure 3-27 and then ground using a grinding machine as shown in Figure 3-25. This helped the samples to be in the desired length (7 0.1 inch ) required for the test. The procedure for the CTE test is as follows: 1. Place the support frame, with LVDT attached, in the water bath and fill the bath with cold tap water. Place the four temperature sensors in the bath at locations that will provide an average temperature for the bath as a whole. To avoid any sticking at the points of contact with specimen, put a very thin film of silicon grease on the end of the support buttons and LVDT tip. 2. Remove the specimen from the moisture room and measure its length at room temperature to the nearest 0.1 mm (0.004 in.). After meas uring the length, place the specimen in the support frame located in the controlled temperat ure bath, making sure th at the lower end of the specimen is firmly seated against the support buttons, and the LVDT tip is seated against the upper end of the specimen.

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55 3. Connect the LVDT and temperature sensors to a data acquisition system which is connected to a laptop computer. 4. Set the temperature of the water bath to 10 1C (50 2 F). When the bath reaches this temperature, allow the bath to remain at this temperature until thermal equilibrium of the specimen has been reached, as indicated by cons istent readings of LVDT to the nearest 0.00025 mm (0.00001 in.) taken every 10 mi nutes over a one-half hour period. 5. Record the temperature readings from the four sensors to the nearest 0.1 C (0.2 F). Record the LVDT reading to the nearest 0. 00025 mm (0.00001 in.). These are the initial readings. 6. Set the temperature of the wate r bath to 50 1C (122 2 F). When the bath reaches this temperature, allow the bath to remain at this temperature until thermal equilibrium of the specimen has been reached, as indicated by cons istent readings of LVDT to the nearest 0.00025 mm (0.00001 in.). 7. Record the temperature readings from the four sensors to the nearest 0.1 C (0.2 F). Record the LVDT reading to the nearest 0. 00025 mm (0.00001 in.). These are the second readings. 8. Set the temperature of the water bath to 10 1 C (50 2 F). When the bath reaches this temperature, allow the bath to remain at this temperature until thermal equilibrium of the specimen has been reached. 9. Record the temperature readings from the four sensors to the nearest 0.1 C (0.2 F). Record the LVDT reading to the nearest 0. 00025 mm (0.00001 in.). These are the final readings. The CTE of one expansion or c ontraction test segment of a concrete specimen is calculated as follows: CTE= ( La/L0) / T Where La = actual length change of specimen dur ing temperature change, mm or in. L0 = measured length of specimen at r oom temperature, mm or in.; and T = measured temperature change (ave rage of the four sensors), C.

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56 The test result is the averag e of the two CTE values obtained from the expansion test segment and contraction test segment, and is calculated as follows: 2 contration CTE expansion CTE CTE Figure 3-25. Coefficient of thermal expansion setup Figure 3-26. Grinder

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57 Figure 3-27. Sawing machine

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58 CHAPTER 4 CONCRETE TEST RESULTS AND DISCUSSION 4.1 Introduction This chapter presents the results of comp ressive strength, elastic modulus, flexural strength, splitting tensile strength, free shrinka ge and coefficient of thermal expansion tests on the different concrete mixtures evaluated in this study. The effects of RC A on the properties of concrete are discussed. 4.2 Analysis of Test Results and Discussion 4.2.1 Compressive Strength Test Results The average compressive strengths at various cu ring periods of different concrete mixtures are presented in Tables 4-1. The individual comp ressive strength values are shown in Table B-1 in Appendix B. Table 4-1. Compressive strength test results Age of Testing (Days) 14 28 Mix number W/C ratio Coarse aggregates Coarse RCA Fine aggregates Fine RCA Total RCA Compressive Strength (psi) 1 0.43 100 0 100 0 0 5241 5425 2 0.43 75 25 75 25 25 5442 6031 Set-1 3 0.43 50 50 50 50 50 4934 5404 1 0.48 100 0 100 0 0 4921 5317 2 0.48 75 25 75 25 25 5287 5578 Set-2 3 0.48 50 50 50 50 50 4892 5083 1 0.53 100 0 100 0 0 4350 4508 2 0.53 75 25 75 25 25 4403 4874 Set-3 3 0.53 50 50 50 50 50 4392 4617 (Note: Coarse aggregate and coarse RCA are vol ume percent by total coarse aggregate, fine aggregate and fine RCA are volum e percent by total fine aggregate. Total RCA is the total percentage replacement of coarse RCA and fine RCA)

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59 4.2.1.1 Effect of RCA on compressive strength Analysis shown in Figures 4-1 to 4-3 show a comparison of compressive strength of concrete mixes made with different percentage RCA. At 0.43 water cement ratio, at 14 days, the compressive strength increase by 4.03% and decreases by 5.86% for 25% RCA and 50% RCA respectively compared to the c ontrol mix. At 28 days, the comp ressive strength is increased by 11.17% and decreased by 0.39% for 25% RCA and 50% RCA respectively. For 0.48 water cement ratio, at 14 days, the compressive strength increase by 7.44% and decreased by 0.59% for 25% RCA and 50% RCA respectively compared to the control mix. At 28days, the compressive strength is increased by 4.91% and decreased 4.40% for 25% RCA and 50% RCA respectively. For 0.53 water cement ratio, at 14 days, the comp ressive strength increase by 1.22% and 0.97% for 25% RCA and 50% RCA respectively compar ed to the control mix. At 28days, the compressive strength is increased by 8.12% and 2.42% for 25% RCA and 50% RCA respectively. From the above, the compressive strength is ge nerally reduced to about 6% for concrete containing 50%RCA at 28 days. There is, however an apparent increase in the compressive strength of the 25% RCA concrete. This could be due to the variability in the test results. It can also be seen that the compressi ve strength increases from 14 days to 28 days in all instances. 4.2.1.2 Effect of water cement ra tio on compressive strength The compressive strength of concrete depends mainly on its water to cement ratio. From Figures 4-4 to 4-5 there is a consistent decrease in compressive strength as the water cement ratio increases for both the control and the RCA concrete. 4.2.2 Elastic Modulus Test Results The average elastic moduli at various curing periods of different concrete mixtures are presented in Tables 4-2. The individual elastic modulus values are show n in Table B-2 in Appendix B.

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60 Table 4-2. Elastic modulus test results Age of Testing (Days) 14 28 Mix number W/C ratio Coarse aggregates Coarse RCA Fine aggregates Fine RCA Total RCA Elastic Modulus (X106psi) 1 0.43 100 0 100 0 0 3.90 4.08 2 0.43 75 25 75 25 25 3.83 3.96 Set-1 3 0.43 50 50 50 50 50 3.71 3.69 1 0.48 100 0 100 0 0 3.85 3.88 2 0.48 75 25 75 25 25 3.90 4.01 Set-2 3 0.48 50 50 50 50 50 3.48 3.67 1 0.53 100 0 100 0 0 3.55 3.70 2 0.53 75 25 75 25 25 3.44 3.72 Set-3 3 0.53 50 50 50 50 50 3.15 3.33 0 1000 2000 3000 4000 5000 6000 7000 02550 Percent RCACompressive Strength (psi) 14 days 28 days Figure 4-1. Effect of RCA on compre ssive strength of 0.43 w/c ratio

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61 0 1000 2000 3000 4000 5000 6000 7000 02550 Percent RCACompressive Strength (psi) 14 days 28 days Figure 4-2. Effect of RCA on compre ssive strength of 0.48 w/c ratio 0 1000 2000 3000 4000 5000 6000 7000 02 55 0 Percent RCACompressive Strength (psi) 14 days 28 days Figure 4-3. Effect of RCA on compre ssive strength of 0.53 w/c ratio

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62 0 1000 2000 3000 4000 5000 6000 0.430.480.53 Water Cement RatioCompressive Strength at 14days (psi) Control 25% RCA 50% RCA Figure 4-4. Effect of water cement ratio on compressive strength at 14days 0 1000 2000 3000 4000 5000 6000 7000 0.43 0.48 0.53 Water Cement RatioCompressive Strength at 28days (psi) Control 25% RCA 50% RCA Figure 4-5. Effect of water cement ratio on compressive strength at 28days

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63 4.2.2.1 Effect of RCA on the elastic modulus of concrete Figure 4-6 to 4-8 presents the analysis of elastic modulus te st. It shows that there is a general reduction of elastic modul us of concrete as the percen tage of RCA increases. At 0.43 water cement ratio, at 14 days, the elastic modul us decreases by 1.80% and 4.87% for 25% RCA and 50% RCA respectively compared to the control mix. At 28days, the elastic modulus is decreased by 2.94% and 9.56% for 25% RCA and 50% RCA respectively. For 0.48 water cement ratio, at 14 days, the elastic modulus in crease by 1.30% and decreased by 9.61% for 25% RCA and 50% RCA respectively compared to th e control mix. At 28 days, the compressive strength is increased by 3.88% and decreased 3.35% for 25% RCA and 50% RCA respectively. For 0.53 water cement ratio, at 14 days, the elas tic modulus decreases by 3.10% and 11.27% for 25% RCA and 50% RCA respectively compared to the control mix. At 28days, the elastic modulus is increased by 0.54% and decreased by 10% for 25% RCA and 50% RCA respectively. From the above results there is a decrease of about 10% in elastic modulus for concrete containing 50% RCA at 28 days. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 02550 Percent RCAElastic Modulus (X10 6 psi) 14 days 28 days Figure 4-6. Effect of RCA on el astic modulus of 0.43 w/c ratio

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64 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 02 55 0 Percent RCAElastic Modulus (X106psi) 14 days 28 days Figure 4-7. Effect of RCA on el astic modulus of 0.48 w/c ratio 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 02550 Percent RCAElastic Modulus (X106psi) 14 days 28 days Figure 4-8. Effect of RCA on el astic modulus of 0.53 w/c ratio 4.2.2.2 Effect of water cement ratio on the elastic modulus of concrete From Figures 4-9 to 4-10 there is a consistent decrease in elastic modulus as the water cement ratio increases for both the control and the RCA concrete.

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65 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0.43 0.48 0.53 Water Cement RatioMOE at 14 days (x106psi)) Control 25% RCA 50% RCA Figure 4-9. Effect of water cement ratio on elastic modulus at 14 days 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0.430.480.53 Water Cement RatioMOE at 28 days (x106psi)) Control 25% RC A 50% RC A Figure 4-10. Effect of water cement ratio on elastic modulus at 28days 4.2.3 Flexural Strength Test Results The average flexural strength at various curing periods of different c oncrete mixtures are presented in Tables 4-3. The i ndividual flexural st rength values are shown in Table B-3 in Appendix B.

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66 Table 4-3. Flexural strength test results Age of Testing (Days) 14 28 Mix number W/C ratio Coarse aggregates Coarse RCA Fine aggregates Fine RCA Total RCA Flexural Strength (psi) 1 0.43 100 0 100 0 0 767 778 2 0.43 75 25 75 25 25 717 768 Set-1 3 0.43 50 50 50 50 50 706 771 1 0.48 100 0 100 0 0 718 761 2 0.48 75 25 75 25 25 672 754 Set-2 3 0.48 50 50 50 50 50 636 688 1 0.53 100 0 100 0 0 654 659 2 0.53 75 25 75 25 25 628 664 Set-3 3 0.53 50 50 50 50 50 576 675 4.2.3.1 Effect of RCA on flexural strength Results shown in Figures 4-11 to 4-13 show a comparison of flexural strength of concrete mixes made with different percen tage RCA. At 0.43 water cement ratio, at 14 days, the flexural strength decreases by 6.52 % and 7.95% for 25% RCA and 50% RCA respectively compared to the control mix. At 28days, the fl exural strength decreases by 1.29% and 0.9% for 25% RCA and 50% RCA respectively. For 0.48 water cement ratio, at 14 days, the flexural strength decreases by 6.41% and 11.42% for 25% RCA and 50% RCA respectively compared to the control mix. At 28days, it decreases by 0.92% and 9.59% for 25% RCA and 50% RCA respectively. For 0.53 water cement ratio, at 14 days, the flexural st rength decrease by 3.98% and 11.93% for 25% RCA and 50% RCA respectively comp ared to the control mix. At 28days, the flexural strength increases by 0.76% and 2.43% for 25% RCA and 50% RCA respectively. The above, result shows a general reduction of fl exural strength with increasing percentage of RCA at 14 days for the different water cement ratios. However at 28day s, there is a general

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67 reduction for the 0.43 and 0.48 water cement rati os and an increase for the 0.53 water cement ratio as the RCA percentage increases. It can al so be seen that the flexural strength increases from 14days to 28days in each instance. 0 100 200 300 400 500 600 700 800 02 55 0 Percent RCAFlexural Strength (psi) 14 days 28 days Figure 4-11. Effect of RCA on flex ural strength of 0.43 w/c ratio 0 100 200 300 400 500 600 700 800 02 55 0 Percent RCAFlexural Strength (psi) 14 days 28 days Figure 4-12. Effect of RCA on flex ural strength of 0.48 w/c ratio

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68 0 100 200 300 400 500 600 700 800 02 55 0 Percent RCAFlexural Strength (psi) 14 day s 28 day s Figure 4-13. Effect of RCA on flex ural strength of 0.53 w/c ratio 4.2.3.2 Effect of water cement rati o on the flexural strength From Figures 4-14 to 4-15 there is a consistent decrease in flexural strength as the water cement ratio increases for both the control and the RCA concrete. 0 100 200 300 400 500 600 700 800 900 0.43 0.48 0.53 Water Cement RatioFlexural Strength at 14 days (psi) Control 25% RCA 50% RCA Figure 4-14. Effect of water cement ra tio on flexural strength at 14 days

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69 580 600 620 640 660 680 700 720 740 760 780 800 0.43 0.48 0.53 Water Cement RatioFlexural Strength at 28 days (psi) Control 25% RC A 50% RC A Figure 4-15. Effect of water cement ra tio on flexural strength at 28 days 4.2.4 Splitting Tensile Strength Test Results The average Splitting Tensile Strength at various curing periods of different concrete mixtures are presented in Tables 4-4. The individual elastic m odulus values are shown in Table B-4 in Appendix B. Table 4-4. Splitting tensile strength results Age of Testing (Days) 14 28 Mix number W/C ratio Coarse aggregates Coarse RCA Fine aggregates Fine RCA Total RCA Splitting Tensile Strength (psi) 1 0.43 100 0 100 0 0 590 537 2 0.43 75 25 75 25 25 559 601 Set-1 3 0.43 50 50 50 50 50 455 522 1 0.48 100 0 100 0 0 538 557 2 0.48 75 25 75 25 25 536 513 Set-2 3 0.48 50 50 50 50 50 508 540 1 0.53 100 0 100 0 0 485 474 2 0.53 75 25 75 25 25 439 483 Set-3 3 0.53 50 50 50 50 50 390 476

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70 4.2.4.1 Effect of RCA on spli tting tensile strength Results shown in Figures 4-16 to 4-18 show a comparison of splitting tensile strength of concrete mixes made with different percentage RCA. At 0.43 water cement ratio, at 14 days, the splitting tensile strength decreases by 5. 25 % and 22.88% for 25% RCA and 50% RCA respectively compared to the control mix. At 28da ys, the splitting tensile strength increases by 11.92% and decreases by 2.79% for 25% RCA and 50% RCA respectively. For 0.48 water cement ratio, at 14 days, the splitting tensile strength decreases by 0.37% and 5.58% for 25% RCA and 50% RCA respectively compared to the control mix. At 28days, it decreases by 7.90% and 3.05% for 25% RCA and 50% RCA respectively. For 0.53 water cement ratio, at 14 days, the splitting tensile strength decrease by 9.49% and 19.59% for 25% RCA and 50% RCA respectively compared to the control mix. At 28da ys, the splitting tensile strength increases by 1.90% and 0.42% for 25% RCA and 50% RCA respectively. The above result shows a general reduction of fl exural strength with increasing percentage of RCA at 14 days for the different water cement ratios. However, at 28days, there is a general reduction for 0.48 water cement ratio and a genera l increase for the 0.53 water cement ratio as the RCA percentage increases. There is also an increase at 25% RCA and a decrease for the 50% RCA for the 0.43 water cement ratio. Generally, the sp litting tensile strength is about the same as the control mix up to 50% RCA at 28 days. 4.2.4.2 Effect of water cement ratio on the splitting tensile strength From Figures 4-19 to 4-20 there is a general d ecrease in flexural Splitting Tensile as the water cement ratio increases for both the cont rol and the RCA concrete. There is however increases in splitting tensile strength at 25% RCA compared to the control mix. This could be due to the variability in the test method.

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71 0 100 200 300 400 500 600 700 02 55 0 Percent RCASplitting Tensile Strength (psi) 14 days 28 days Figure 4-16. Effect of RCA on splitti ng tensile strength of 0.43 w/c ratio 0 100 200 300 400 500 600 700 02 55 0 Percent RCASplitting Tensile Strength (psi) 14 days 28 days Figure 4-17. Effect of RCA on splitti ng tensile strength of 0.48 w/c ratio 0 100 200 300 400 500 600 700 02 55 0 Percent RCASplitting Tensile Strength (psi) 14 days 28 days Figure 4-18. Effect of RCA on splitti ng tensile strength of 0.53 w/c ratio

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72 0 100 200 300 400 500 600 700 0.43 0.48 0.53 Water Cement Ratio14 Days Splitting Tensile Strength (psi) Control 25% RCA 50% RCA Figure 4-19. Effect of water cement ratio on splitting tensile strength at 14 days 0 100 200 300 400 500 600 700 0.430.480.53 Water Cement Ratio28 Days Splitting Tensile Strength (psi) Control 25% RC A 50% RC A Figure 4-20. Effect of water cement ratio on splitting tensile strength at 28 days 4.2.5 Free Shrinkage Test Results The average free shrinkage values at 28 days of curing for the different concrete mixtures are presented in Table 4-5. The individual free shri nkage strain values are shown in Table B-5 in Appendix B.

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73 4.2.5.1 Effect of RCA on free shrinkage Results shown in Figures 4-21 to 4-23 show a comparison of free shrinkage of concrete mixes made with different percentage RCA. At 0.43 water cement ratio, at 28 days, the free shrinkage increases by 192.98 % for 25% RCA and remains the sa me 50% RCA compared to the control mix. For 0.48 water cement ratio, at 28 days, the free shrinkage decreases by 34.48% and increases by 22.99% for 25% RCA and 50% RCA respectively compared to the control mix. For 0.53 water cement ratio, at 28 days, the fr ee shrinkage increases by 285% and 1250% for 25% RCA and 50% RCA respectively compared to the control mix. The above result does not show a consistent trend in free shrinkage with increasing percentage of RCA. However, th ere is a general increase in free shrinkage as the percentage of RCA increases. 4.2.5.2 Effect of water cement ratio on the free shrinkage From Figure 4-24 there is a general increase in free shrinkage as the water cement ratio increases for concrete containing 50% RCA. However, there is no clear trend for concrete the control mix and concre te containing 25% RCA. Table 4-5. Free shrinkage test results Age of Testing (Days) 28 Mix number W/C ratio Coarse aggregates Coarse RCA Fine aggregates Fine RCA Total RCA Free Shrinkage (x10-6 in/in) 1 0.43 100 0 100 0 0 57 2 0.43 75 25 75 25 25 167 Set-1 3 0.43 50 50 50 50 50 57 1 0.48 100 0 100 0 0 87 2 0.48 75 25 75 25 25 57 Set-2 3 0.48 50 50 50 50 50 107 1 0.53 100 0 100 0 0 20 2 0.53 75 25 75 25 25 77 Set-3 3 0.53 50 50 50 50 50 270

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74 0 50 100 150 200 250 300 02 55 0 Percent RCAFree Shrinkage (X106 in/in) 28 days Figure 4-21. Effect of RCA on fr ee shrinkage of 0.43 w/c ratio 0 50 100 150 200 250 300 02550 Percent RCAFree Shrinkage (X10-6 in/in) 28 days Figure 4-22. Effect of RCA on fr ee shrinkage of 0.48 w/c ratio 0 50 100 150 200 250 300 02 55 0 Percent RCAFree Shrinkage (X10-6 in/in) 28 days Figure 4-23. Effect of RCA on fr ee shrinkage of 0.53 w/c ratio

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75 0 50 100 150 200 250 300 02 55 0 Percentage of RCAFree Shrinkage (X10-6 in/in) 0.43 0.48 0.53 Figure 4-24. Effect of water cement ratio on RCA at 28 days 4.2.6 Coefficient of Thermal Expansion Test Results The mean coefficients of thermal expansion at 28 days of curing for the different concrete mixtures are shown in Table 4-6. Individual coefficient of therma l expansion values are shown in Table B-6. Table 4-6. Coefficient of thermal expansion test results Age of Testing (Days) 28 Mix number W/C ratio Coarse aggregates Coarse RCA Fine aggregates Fine RCA Total RCA Coefficient of thermal expansion (10-6/oF) 1 0.43 100 0 100 0 0 5.51 2 0.43 75 25 75 25 25 5.41 Set-1 3 0.43 50 50 50 50 50 5.16 1 0.48 100 0 100 0 0 5.39 2 0.48 75 25 75 25 25 5.46 Set-2 3 0.48 50 50 50 50 50 5.29 1 0.53 100 0 100 0 0 5.26 2 0.53 75 25 75 25 25 5.20 Set-3 3 0.53 50 50 50 50 50 5.47

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76 4.2.6.1 Effects of RAP on coefficient of thermal expansion of concrete Figure 4-25 to figure 4-27 shows the results of coefficient of thermal expansion for concrete with different RCA conten ts at different water cement ratio s. It shows that coefficient of thermal expansion for concrete mixtures co ntaining RCA is about the same as the control mixture. At 0.43 water cement ratio, the coeffi cient of thermal expans ion decreases by 1.82% and 6.35 % for 25%RCA and 50%RCA respectively compared to the control mix. At 0.48 water cement ratio, the coefficient of thermal expansion increases by 1.30% at 25% RCA and decreases by 1.86% at 50% RCA compared to th e control mix. At 0.53 water cement ratio, the coefficient of thermal expansion decreases at 25% RCA and then increases at 50% RCA compared with the control mix. The above analysis depicts that there is no clear difference in the coefficient of thermal expansion of the control mi x and the concrete with the different percentage of RCA. The slight difference may be due to the variability in the test results. 4.2.6.2 Effect of water cement ratio on the coefficient of thermal expansion From Figure 4-28 there is no difference in th e coefficient of thermal expansion as the water cement ratio increases fo r both the concrete containing the RCA and the control mix. 0 1 2 3 4 5 6 02550Coefficient of Thermal Expansion (X10-6 in/in/oF) 28 days Figure 4-25. Effect of RCA on coefficient of thermal e xpansion of 0.43 w/c ratio

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77 0 1 2 3 4 5 6 02550Coefficient of Thermal Expansion (X10-6 in/in/oF) 28 days Figure 4-26. Effect of RCA on coefficient of thermal e xpansion of 0.48 w/c ratio 0 1 2 3 4 5 6 02 55 0Coefficient of Thermal Expansion (X10-6 in/in/oF) 28 days Figure 4-27. Effect of RCA on coefficient of thermal e xpansion of 0.53 w/c ratio 0 1 2 3 4 5 6 0.43 0.48 0.53 Water Cement RatioCoefficient of Thermal Expansion(X10-6 in/in/oF) Control 25% RCA 50% RCA Figure 4-28. Effect of water cement ratio on coefficient of thermal expansion at 28days

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78 4.3 Summary of Test Results From the test results, the compressive strength and elastic m odulus are reduced slightly as the percentage of RCA increases up to 50%. The splitting tensile strength, flexural strength and coefficient of thermal expansion are about the sa me as the control mix for concrete containing RCA up to 50%. The drying shrinkage decreases s lightly as the percentage of RCA increases up to 50%.

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79 CHAPTER 5 EVALUATION OF POTENTIAL PERFORMANCE OF CONCRETE CONTAINING RCA IN PAVEME NT 5.1 Finite Element Model Used to Perform Stress Analysis The nine different concrete mixes were analyzed to determine their performance on a typical concrete pavement in Florida. Their el astic modulus, compressive strength, density and coefficient of thermal expansion were used to m odel the concrete. The anal ysis was performed to determine the maximum stresses in the concrete slab if it were loaded by a 22-kip wheel applied at the critical loading positions, at the slab corner and middle edge as shown in Figure 5-2. Temperature differentials of +20F, 0F and -20F in the concrete slab were used in the analysis. The FEACONS IV (Finite Element Analysis of Concrete Slabs version IV) program was used to perform the stress analysis. The FEAC ONS program was previously developed at the University of Florida for FDOT for the analysis of PCC pavements subjected to load and thermal effects, and had demonstrated to be a fairly effect ive and reliable tool for this type of analysis. Figure 5-1 shows the finite element model used to perform the stress an alysis. Figure 5-3 shows the details of input guide used for FEACONS IV program. Analysis us ing the FEACONS model was performed to determine stresses in a 10-inch concrete pavement slab if it were loaded by 22kip axle load at two critical loading positions, namely at the slab corner and at the middle of the slab edge. The middle of the slab edge is the most critical loading positi on in the day time when the temperature differential in the slab is positiv e, while the slab corner is the most critical loading position at night when the temperature differential is negative. The following parameters were used to model the concrete pavement. 1. Slab thickness = 10 in; slab lengt h = 15 ft; slab width = 12 ft 2. Subgrade modulus, ks = 0.3 kci; edge stiffness, ke = 30 ksi 3. Joint linear stiffness, kl = 500 ksi; Joint torsion stiffness kt = 1000 k-in/in

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80 Figure 5-1. Finite element model used in FEACONS IV analysis Figure 5-2. 22-kip wheel load at slab corner and middle edge

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81 Figure 5-3. Example input file inpu t used for the FEACONS IV program 5.2 Results of Stress Analysis using FEACONS IV Analysis Using the stresses calculated by FEACONS IV program and the determined flexural strength, stress-strength ratios were calculated to compare the performance of the concrete with RCA. Tables 5-1 to 5-3 shows the st ressstrength ratios at the corn er and middle edge of the slab with +20F, -20F and +0F temperature differential. Mesh details used for all the analysis

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82 Table 5-1. Computed maximum stresses and stress-strengt h ratios in concrete paveme nt containing 0.43 w/c ratio Temperature difference of +20oF between top and bottom Computed Stress (psi) Stress Ratio Mix No. W/C ratio Coarse Agg. Coarse RCA Fine Agg. Fine RCA Total RCA Mean 28day water saturated CTE (10-6/oF) Mean 28day Modulus of Elasticity (ksi) Mean 28-day Modulus of Rupture (psi) CornerMiddle Edge CornerMiddle Edge 1 0.43 100 0 100 0 0 5.83 4080 778 400 483 0.51 0.62 2 0.43 75 25 75 25 25 5.41 3960 768 410 510 0.53 0.66 3 0.43 50 50 50 50 50 5.16 3690 771 388 474 0.50 0.61 Temperature difference of -20oF between top and bottom Computed Stress (psi) Stress Ratio Mix No. W/C ratio Coarse Agg. Coarse RCA Fine Agg. Fine RCA Total RCA Mean 28day water saturated CTE (10-6/oF) Mean 28day Modulus of Elasticity (ksi) Mean 28-day Modulus of Rupture (psi) CornerMiddle Edge CornerMiddle Edge 1 0.43 100 0 100 0 0 5.83 4080 778 333 312 0.43 0.40 2 0.43 75 25 75 25 25 5.41 3960 768 354 332 0.46 0.43 3 0.43 50 50 50 50 50 5.16 3690 771 312 291 0.40 0.38 Temperature difference of 0oF between top and bottom Computed Stress (psi) Stress Ratio Mix No. W/C ratio Coarse Agg. Coarse RCA Fine Agg. Fine RCA Total RCA Mean 28day water saturated CTE (10-6/oF) Mean 28day Modulus of Elasticity (ksi) Mean 28-day Modulus of Rupture (psi) CornerMiddle Edge CornerMiddle Edge 1 0.43 100 0 100 0 0 5.83 4080 778 170 187 0.22 0.24 2 0.43 75 25 75 25 25 5.41 3960 768 175 192 0.23 0.25 3 0.43 50 50 50 50 50 5.16 3690 771 170 186 0.22 0.24

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83 Table 5-2. Computed maximum stresses and stress-strengt h ratios in concrete paveme nt containing 0.48 w/c ratio Temperature difference of +20oF between top and bottom Computed Stress (psi) Stress Ratio Mix No. W/C ratio Coarse Agg. Coarse RCA Fine Agg. Fine RCA Total RCA Mean 28day water saturated CTE (10-6/oF) Mean 28day Modulus of Elasticity (ksi) Mean 28-day Modulus of Rupture (psi) CornerMiddle Edge CornerMiddle Edge 1 0.48 100 0 100 0 0 5.84 3880 761 392 471 0.52 0.62 2 0.48 75 25 75 25 25 5.46 4010 754 402 489 0.53 0.65 3 0.48 50 50 50 50 50 5.29 3670 688 384 447 0.56 0.65 Temperature difference of -20oF between top and bottom Computed Stress (psi) Stress Ratio Mix No. W/C ratio Coarse Agg. Coarse RCA Fine Agg. Fine RCA Total RCA Mean 28day water saturated CTE (10-6/oF) Mean 28day Modulus of Elasticity (ksi) Mean 28-day Modulus of Rupture (psi) CornerMiddle Edge CornerMiddle Edge 1 0.48 100 0 100 0 0 5.84 3880 761 322 300 0.42 0.39 2 0.48 75 25 75 25 25 5.46 4010 754 337 315 0.45 0.42 3 0.48 50 50 50 50 50 5.29 3670 688 306 278 0.44 0.40 Temperature difference of 0oF between top and bottom Computed Stress (psi) Stress Ratio Mix No. W/C ratio Coarse Agg. Coarse RCA Fine Agg. Fine RCA Total RCA Mean 28day water saturated CTE (10-6/oF) Mean 28day Modulus of Elasticity (ksi) Mean 28-day Modulus of Rupture (psi) CornerMiddle Edge CornerMiddle Edge 1 0.48 100 0 100 0 0 5.84 3880 761 170 186 0.22 0.24 2 0.48 75 25 75 25 25 5.46 4010 754 172 188 0.23 0.25 3 0.48 50 50 50 50 50 5.29 3670 688 167 184 0.24 0.27

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84 Table 5-3. Computed maximum stresses and stress-strengt h ratios in concrete paveme nt containing 0.53 w/c ratio Computed Stress (psi) Stress Ratio Mix No. W/C ratio Coarse Agg. Coarse RCA Fine Agg. Fine RCA Total RCA Mean 28day water saturated CTE (10-6/oF) Mean 28day Modulus of Elasticity (ksi) Mean 28-day Modulus of Rupture (psi) CornerMiddle Edge CornerMiddle Edge 1 0.53 100 0 100 0 0 4.98 3700 659 372 420 0.56 0.64 2 0.53 75 25 75 25 25 5.20 3720 664 376 439 0.57 0.66 3 0.53 50 50 50 50 50 5.47 3300 675 376 437 0.56 0.65 Temperature difference of -20oF between top and bottom Computed Stress (psi) Stress Ratio Mix No. W/C ratio Coarse Agg. Coarse RCA Fine Agg. Fine RCA Total RCA Mean 28day water saturated CTE (10-6/oF) Mean 28day Modulus of Elasticity (ksi) Mean 28-day Modulus of Rupture (psi) CornerMiddle Edge CornerMiddle Edge 1 0.53 100 0 100 0 0 4.98 3700 659 278 259 0.42 0.39 2 0.53 75 25 75 25 25 5.20 3720 664 292 272 0.44 0.41 3 0.53 50 50 50 50 50 5.47 3300 675 293 274 0.43 0.41 Temperature difference of 0oF between top and bottom Computed Stress (psi) Stress Ratio Mix No. W/C ratio Coarse Agg. Coarse RCA Fine Agg. Fine RCA Total RCA Mean 28day water saturated CTE (10-6/oF) Mean 28day Modulus of Elasticity (ksi) Mean 28-day Modulus of Rupture (psi) CornerMiddle Edge CornerMiddle Edge 1 0.53 100 0 100 0 0 4.98 3700 659 162 178 0.25 0.27 2 0.53 75 25 75 25 25 5.20 3720 664 165 182 0.25 0.27 3 0.53 50 50 50 50 50 5.47 3300 675 163 179 0.24 0.27

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85 5.2.1 Effects of RCA on Stress-Strength Ratio of Concrete Pavement with varying Water to Cement Ratio Figure 5-4 to Figure 5-9 shows th e comparison of the stressstrength ratios at the corner and middle edge of the slab with +20F, and 20 F temperature differentials for various water cement ratios. It shows that stress-strength ratio of the control mix is about the same for the concrete containing RCA at the middle edge and corner of the slab. At 28 days, with +20F temperature differential, the stress-strength ratio at the middle edge of the slab for the concrete mixtures with 043 water to cement ratio, there is an increase of 6.54% and decrease of 1.61% for 25% and 50% respectively compared to the control mix. For 0.48 water cement ratio there is an increase of 4.84% and 4.84% for 25% RCA and 50% RCA respectively for concrete compared to the control mix. For 0.53 water cement ratio there is an increase of 3.13% and 1.56% for 25% RCA and 50% RCA respectively for concrete compared to the cont rol mix. At 28 days, with 20F temperature differential, the stress-strength ratio at the corner edge of the slab for the concrete mixtures with 043 water to cement ratio, there is an incr ease of 6.98% and decrease of 6.96% for 25% and 50% respectively compared to the control mix. For 0.48 water cement ratio there is an increase of 7.14% and 4.76% for 25% RCA and 50% RCA resp ectively for concrete compared to the control mix. For 0.53 water cem ent ratio there is an increase of 4.76% and 2.38% for 25% RCA and 50% RCA respectively for c oncrete compared to the control mix. 5.2.2 Observation on Result s of Stress Analysis From the results presented in Tables 5-1 thr ough Table 5-3, it can be seen that the most critical loading condition, which results in the maximum computed stress, was the condition when the 22-kip axle load was applied at the middle edge of the slab when the temperature differential is +20F. Thus the observation of poten tial performance of the various concrete mixes will be focused mainly on the computed stress-str ength ratio at this condition. From the results

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86 presented in Table 5-1 through Tabl e 5-8, it can be seen that the computed stressstrength of the control mix was generally about the same as a c oncrete with containing RCA. Thus the concrete containing RCA up to about 50% will have the same performance as the concrete containing virgin aggregates. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 02 55 0Stress to strength ratio 28 days Figure 5-4. Effect of RCA on stress-strength ra tios at the middle edge of slab with +20oF temperature differential for 0.43 water cement ratio. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 02550Stress to strength ratio 28 days Figure 5-5. Effect of RCA on stress-strength ra tios at the middle edge of slab with +20oF temperature differential for 0.48 water cement ratio.

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87 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 02 55 0 C Stress to strength ratio 28 days Figure 5-6. Effect of RCA on stress-strength ra tios at the middle edge of slab with +20oF temperature differential for 0.53 water cement ratio. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 02550Stress to strength ratio 28 days Figure 5-7. Effect of RCA on stre ss-strength ratios at the corn er edge of slab with -20oF temperature differential for 0.43 water cement ratio.

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88 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 02 55 0 PRCA Stress to strength ratio 28 days Figure 5-8. Effect of RCA on stress-strength ra tios at the corner edge of slab with -20oF temperature differential for 0.48 water cement ratio. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 02550Stress to strength ratio 28 days Figure 5-9. Effect of RCA on stress-strength ra tios at the corner edge of slab with -20oF temperature differential for 0.53 water cement ratio.

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89 CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS 6.1 Conclusions This study evaluated feasibility of using conc rete containing recycled concrete aggregate (RCA) in concrete pavement applications. C oncrete containing 0%, 25%, 50% of RCA were produced in the laboratory, and evaluated for th eir properties which are relevant to performance of concrete pavements. Results of the laborat ory testing program indi cate that compressive strength and elastic modulus decreas es slightly as the percentage of RCA increases. The splitting tensile strength, flexural strength and coefficient of thermal expa nsion are about the same for the control mix and the concrete containing RCA. Th e drying shrinkage decrea ses slightly as the percentage of RCA increases. When a finite el ement analysis was performed to determine the maximum stresses in typical concrete pavements in Florida under critical temperature and load conditions, the maximum stresses to strength ratios in the pavement were found to be about the same for the control mix and concrete contai ning RCA. Thus the RCA will have the same performance as the control mix. With the use of RCA up to about 50%, there will not be much difference in its performance compared with concre te containing virgin aggregate. Thus the main advantage for the use of the RCA is the economical and environmental benefit. 6.2 Recommendations The results of this limited labor atory testing program and finite element analysis indicate that the use of RCA as aggregate replacement in pavement concrete appears to be not only feasible but also perform the same as concre te containing virgin a ggregates. It is thus recommended that further research be conducted in this area to further validate this finding. It is recommended that further research wo rk be done in the following areas:

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90 1. To conduct a full factorial experiment to inves tigate the properties of concrete containing RCA as affected by (a) the mechanical prope rties of the RCA, (b) the gradation of the RCA, (c) properties of the virg in aggregate, (d) w/c of th e concrete and (e) mineral admixtures such as fly ash and ground blast-furnace slag. 2. To evaluate the potential performance of the va rious concrete mixes tested in the factorial experiment using finite element analysis wh ere the maximum stresses in typical concrete pavements in Florida under critical temperat ure and load conditions would be determined using the measured properties. The results of th ese analyses can then be used to develop a method for optimizing a concrete mix design incorporating RCA. 3. To conduct accelerated pavement testing on conc rete pavement slabs made with concrete containing RCA to evaluate the actual fiel d performance of these concrete mixes. 4. To perform a life cycle cost analysis to determine the actual cost savings from the use of RCA 5. To perform a computer x-ray tomography on the RCA to assess the degree of distress existing in it. 6. To perform a scanning electron microscopy to exam the microstructu re of the concrete containing RCA and determine how the va rious constituents can be improved.

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91 APPENDIX A INPUT GUIDE FOR FEACONS IV PROGRAM There are tw o types of input to the FEACONS IV program they are: 1. The input data which describe the problem. 2. The command statements which give specif ic instructions for execution of the program. Both the input data and the command statements must appear in the i nput file in the same order as specified. All of the input data are freeformatted so that the data are not limits to any specific columns. Adjoining data must be se parated by a blank or a comma. However, a command statement must start at the first column of each line. Inputs to the program are listed in Table A-1. Table A-1. Input guide for FEACONS IV program Item Input Mandatory (M) or Optional (O) 1 Number of runs M 2 Number of x-divisions on slab #1 Number of x-divisions on slab #2 Number of x-divisions on slab #3 Number of y-divisions M 3 Number of bonded layers (1 or 2) M 4 Thickness of top layer (in inches), Elastic modulus of top layer (in ksi), Poissons ratio of both layers M 5 Skip if number of bonded layers = 1, otherwise Thickness of second layer (in inches) Elastic modulus of second layer (in ksi) 6 Thickness of subbase (in inches) Elastic modulus of subbase layer (ksi) (enter 0, 0 if not used) M 7 x-coordinates of nodes along the x axis (in inches) M

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92 Table A-1. Continued Item Input Mandatory (M) or Optional (O) 8 y-coordinates of nodes along the y axis (in inches) M 9 Command LINEAR (for linear sub-grade), or NONLINEAR (for nonlinear sub-grade) M 10 Subgrade modulus in kci (if LINEAR), or Coefficient A, Coeffici ent B (if NONLINERAR) (The force-deflection rela tionship is: F = Ad + Bd2, where F = force/area in ksi, and d = deflection in inches) M 11 Command GAP (if initial gaps are to be read), or NO GAP M 12 Skip if NO GAP. Otherwise, input: Number of gaps Node number, Depth of gap in inches (Use one line for each node with gap) M 13 Command CONC FORCE (if concentrated loads are to be read in), or NO CONC FORCE M 14 Skip if NO CONC FORCE, Otherwise: Number of Concentrated Forces (on one line) Node number, Magnitude of load in kips (use one line for each node) M 15 Command UNIF LOAD (if uniform load is to be read in), or NO UNIF LOADS M 16 Skip if NO UNIF LOAD. Otherwise: Number of elements with unifo rm loads (on one line) Element number, Uniform load in ksi (use one line for each element) M 17 Density of 1st layer (in pcf) M 18 Skip if number of layers = 1, otherwise Density of 2nd layer (in pcf) M 19 Command TEMPERATURE EF FECT (if effects of temperature differentials are to be considered) or No TEMPERATURE EFFECT (Temperature effect can not be considered if a subbase layer is used.) M 20 Skip if NO TEMPERATURE EFFECT. Otherwise: Coefficient of thermal expansion (in 1/.F), Temperature at the top of the slab (in .F) Temperature at the bottom of the slab (in .F) M

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93 Table A-1. Continued Item Input Mandatory (M) or Optional (O) 21 Spring coefficient for the edges (in ksi) M 22 Linear spring coefficient for the joints (in ksi), Torsional spring coefficient for the joints (in k-in) M 23 Linear spring coefficient for th e dowel joints (in ksi), Torsional spring coefficient for the dowel joints (in k/in) SLIP (in inches) M 24 Number of load increments to co mpute the effects of slab weight, Number of load increments to compute the effects of temperature Differentials, Number of load increments to compute the effects of applied loads M 25 Command PRINT INITIAL DEFL ECTION (if deflection caused by the combined effects of slab weight and temperature differentials are to be printed) O 26 If the command PRINT INTIAL DEFLECTION is read in, read in: Total number of sets of nodes to be printed, Starting node number, Ending node number, Increment between the nodes (the last three numbers represent a node set. The next node set follows here if there is more than one node set) 0 27 Command PRINT DEFLECTION (i f deflections caused by applied loads are to be printed) O 28 If PRINT DEFLECTION is read in, read in: Total number of sets of nodes to be printed, Starting node number, Ending node number, Increment between the nodes (Similar to No.26) O 29 Command PRINT MAXIMUM DEFLECTION, read in: (If maximum deflections between sp ecific nodes are to be printed) O 30 If PRINT MAXIMUM DEFLECTION, read in: Number of sets of nodes, Starting node number, Ending node number, Increment (Similar to No.26) O

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94 Table A-1. Continued Item Input Mandatory (M) or Optional (O) 31 Command PRINT MOMENTS (If moments at the nodes are to be printed) O 32 If PRINT MOMENTS, read in: Number of sets of nodes, Starting node number, Ending node number, Increment (Similar to no.26) O 33 Command PRINT MAXIMUM MOMENTS if maximum moments between specific nodes are to be printed) O 34 If PRINT MAXIMUM MOMENTS, read in: Number of sets of nodes, Starting node number, Ending node number, Increment (Similar to No.26) O 35 Command PRINT TOP STRESSES (If stresses at the top of th e slabs are to be printed) O 36 If PRINT TOP STRESSES, read in: Number of sets of nodes, Starting node number, Ending node number, Increment (Similar to No.26) O 37 Command PRINT MAXIMUM STRESSES (If maximum stresses between specific nodes are to be printed) 38 If PRINT BOTTOM STRESSES, read in: (Similar to No.26) 39 Command PRINT 1STLAYE R BOTTOM STRESSES (if stresses at the bottom of the top layer are to be printed) 40 If PRINT MAXIMUM STRESSES, then read in: Number of sets of nodes, Starting node number, Ending node number, Increment (Similar to No.26) 41 Command PRINT BOTTOM STRESSES (If stresses at the bottom of th e slabs are to be printed)

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95 Table A-1. Continued Item Input Mandatory (M) or Optional (O) 42 If PRINT PRINCIPAL STRESSES, then read in: Number of sets of nodes, DEG, Starting node number, Ending node number,Increment (If DEG = 1, angles will be in degrees. If DEG = 2, angles will be in radians.) (The last four numbers represent a node set. The next node set follows here if there is more than one node set) 36A Command PRINT 1STL AYER BOTTOM STRESSES (If stresses at the bottom of the top layer are to be printed) O 36B If PRINT 1STLAYER BOTTOM ST RESSES is read in, read in: Total number of sets of nodes to be printed, Starting node number, Ending node number, Increment between the nodes. (This is similar to item 26) O 38A Command PRINT 2NDLAYER TOP STRESSES (if stresses at the top of the bottom layer are to be printed) O 38B If PRINT 2NDLAYER TOP STRESSES is read in, read in: Total number of sets of nodes to be printed, Starting node number, Ending node number, Increment between nodes. (This is similar to item 26) O 38C Command PRINT SUBBASE TOP STRESSES (if stresses at the top of the unbonded subbase layer are to be printed) O 38D If PRINT SUBBASE TOP STRESSES read in, read in: Total number of sets of nodes to be printed, Starting node number, Ending node number, Increment between the nodes. (This is similar to item 26) O 39 Command PRINT MAXIMUM STRESSES 1STLAYER TOP (if maximum stresses at the top of the top layer, between specific nodes, are to be printed) [revised] O 40 If PRINT MAXIMUM STRESSES 1STLAYER TOP, then read in: Total number of sets of nodes to be printed, Starting node number, Ending node number, Increment between the nodes. (Similar to No.26) [revised] O

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96 Table A-1. Continued Item Input Mandatory (M) or Optional (O) 40A Command PRINT MAXIMUM STRESSES 1STLAYER BOTTOM (if maximum stresses at the botto m of the top layer, between specific nodes, are to be printed) O 40B If PRINT MAXIMUM STRESSES 1STLAYER BOTTOM, then (inputs similar to item 26) O 40C Command PRINT MAXIMUM STRESSES 2NDLAYER BOTTOM (if maximum stresses at the botto m of the bottom layer, between specific nodes, are to be printed) O 40D If PRINT MAXIMUM STRESSES 2NDLAYER BOTTOM, then (inputs similar to item 26) O 40E Command PRINT MAXIMUM STRESSES 2NDLAYER TOP (if maximum stresses at the top of the bottom layer, between specific nodes, are to be printed) O 40F Command PRINT MAXIMUM STRESSES SUBASE TOP (if maximum stresses at the top of the unbonded subbase layer, between specific nodes, are to be printed) O 43 Command PRINT MAXIMUM PRINCIPAL STRESSES (If maximum principal stresses between specific nodes are to be printed) (For top stresses only) O 44 If PRINT MAXIMUM PRIN CIPAL STRESSES, then: Number of sets of nodes, Starting node number, Ending node number, Increment. (Similar to item 26) O 45 Command FINISH (This is to mark the end of a set of data. The next set of data in the same formats as items (2) through (39) follows here, if there is more than one run to be made.) M Numbering of Nodes and Element In using the FEACONS IV program it is essential that the nodes and the elements of the chosen finite-element mesh are numbered prop erly. The nodes and elements are numbered from left to right and from bottom to top such that they start at the lower left corner of the first slab,

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97 and proceed up in the vertical di rection for the full width of the slab. The number of nodes and the y coordinates of the chosen nodes in the y dir ection (along the width) in each slab should be the same as those of the other slabs. However, the number of nodes and distances between two nodes in the x direction (al ong the length) may vary from one slab to another. Figure A-1. Example of number of nodes and elements

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98 APPENDIX B LABORATORY TEST RESULTS Table B-1. Results of com pre ssive strength tests (psi) Age of testing (days) 14 days 28 days Samples Samples w/c 1 2 3 1 2 3 Control Mix 0.43 5156 5122 5443 5495 5413 5367 0.48 4956 4875 4932 5355 5391 5205 0.53 4255 4203 4591 4527 4534 4463 25% RCA 0.43 5371 5462 5524 6008 5914 6171 0.48 5227 5421 5213 5608 5555 5570 0.53 4518 4433 4257 4982 4798 4841 50% RCA 0.43 4857 4872 5072 5571 5572 5070 0.48 4693 4931 5051 5048 5185 5015 0.53 4318 4484 4375 4625 4586 4640 Table B-2. Results of elastic modulus tests (x106psi) Age of testing (days) 14 days 28 days Samples Samples w/c 1 2 1 2 Control Mix 0.43 3.9 3.9 4.00 4.15 0.48 3.85 3.85 3.90 3.85 0.53 3.55 3.55 3.65 3.75 25% RCA 0.43 3.85 3.80 3.93 3.98 0.48 3.87 3.92 4.02 4.00 0.53 3.45 3.42 3.68 3.75 50% RCA 0.43 3.47 3.95 3.73 3.65 0.48 3.50 3.45 3.68 3.65 0.53 3.10 3.20 3.35 3.30 Table B-3. Results of fle xural strength tests (psi) Age of testing (days) 14 days 28 days Samples Samples w/c 1 2 3 1 2 3 Control Mix 0.43 754 791 755 728 778 827

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99 Table B-3. Continued Age of testing (days) 14 days 28 days Samples Samples w/c 1 2 3 1 2 3 Control Mix 0.48 710 730 713 780 742 759 0.53 637 658 666 664 648 664 25% RCA 0.43 685 710 756 809 747 748 0.48 631 689 696 794 726 741 0.53 633 629 621 668 647 678 50% RCA 0.43 700 731 686 757 790 767 0.48 555 641 712 719 706 638 0.53 583 553 591 647 715 665 Table B-4. Results of splitti ng tensile strength tests (psi) Age of testing (days) 14 days 28 days Samples Samples w/c 1 2 3 1 2 3 Control Mix 0.43 633 528 610 562 509 539 0.48 539 515 559 545 560 567 0.53 466 501 489 561 439 422 25% RCA 0.43 589 581 506 567 594 643 0.48 478 619 510 498 506 535 0.53 438 428 450 434 549 467 50% RCA 0.43 375 479 510 402 631 534 0.48 491 477 555 556 525 539 0.53 371 321 478 475 468 485 Table B-5. Results of free shrinkage tests (10-6 in/in) Age of testing (days) 28 days Samples w/c 1 2 3 Control Mix 0.43 50 70 50 0.48 20 70 170 0.53 30 0 30

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100 Table B-5. Continued Age of testing (days) 28 days Samples w/c 1 2 3 25% RCA 0.43 140 190 170 0.48 80 50 40 0.53 80 40 110 50% RCA 0.43 50 60 60 0.48 80 170 70 0.53 270 270 270 Table B-6. Results of coefficien t of thermal expansion tests (10-6 /oF) Age of testing (days) 28 days Samples w/c 1 2 3 Control Mix 0.43 5.83 5.37 5.32 0.48 5.85 5.31 5.01 0.53 4.98 5.45 5.36 25% RCA 0.43 5.76 5.00 5.48 0.48 5.54 5.35 5.49 0.53 5.19 5.31 5.09 50% RCA 0.43 5.23 5.28 4.97 0.48 5.38 5.43 5.05 0.53 5.73 5.19 5.47

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101 LIST OF REFERENCES Bernier, G., Malier, Y. and Mazwrs J (1978), New Material from Concrete Demolition waste, The bibeton proceedings, International Confer ence on the Use of By-Products and Waste civil Engineering, pp. 157-162. In Lamond, J. F. et al, Removal and Reuse of Hardened Concrete ACI committee 555 report March 2001 Buck, A. D., (1976), Recycled concrete, Misc ellaneous Paper C-72-14, Report 2, U.S. Army Engineers Waterways Experiment station, Vicksburg, Miss, 200pp. Building Contractors Society of Japan, (1978) Study on Recycled Aggregate and Recycled Aggregate Concrete, Concrete Journal, V. 16, No. 7, pp. 18-31. (in Japanese) In Lamond, J.F. et al, Removal and Reuse of Hardened Concrete ACI committee 555 report March 2001 Chesner, W., Collins, R., MacKay, M. and Emery, J. (1998) User Guidelines for Wasteand Byproduct Materials in Pavement Cons truction. FHWA Report FHWA-RD-97-148, Federal Highway Administra tion, McLean, Virginia. Chini, A. and Kuo, S. S. (1998). Guidelines and Specifications for the Use of Reclaimed Aggregates in pavement. Florida Depart ment of Transportation Final Report for Contract BA 509, State Material s Office, Gainesville, FL Chuang-Tsair S. (1989) Recycled Portland Cement Concrete as Aggregate for New Concrete Pavements Masters Thesis of University of Florida, Gainesville. Environmental Council for Conc rete Organizations (ECCO) [Internet] [updated 2003 Aug. 26; cited 2009 July 7]. Available from: http://www.ecco.org/pdfs/Ev22.pdf Guang Li, 2004, The Effect of Moisture Content on the Tensile Strength Properties of Concrete, Thesis Presented to the Graduate School of University of Florida. Hansen, T. C., and Narud, H, (1983) Strengt h of Recycled Concrete Made from Crushed Concrete Coarse Aggregate, Concrete Intern ational, V. 5, No. 1, Jan., pp. 79-83. In Lamond, J.F. et al, Removal and Reuse of Hardened Concrete ACI committee 555 report March 2001 Hansen, T. C., (1986), The Second RILEM State of the Art Report on Recycled Aggregates and Recycled Aggregate Concrete, Materials a nd Structures, V.1, No. 111, May-June, pp. 201-246. In Lamond, J.F. et al, Removal and Reuse of Hardened Concrete ACI committee 555 report March 2001 Hasaba, S.; Kawamura, M.; Toriik K.; and Takemoto, K., (1981) Drying Shrinkage and Durability of the Concrete Ma de of Recycled Concrete Aggregate, The Japan Concrete Institute, V. 3, pp. 55-60. In Lamond, J.F. et al, Removal and Reuse of Hardened Concrete ACI committee 555 report March 2001

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102 Hooton, R. D Influence of SF replacement of ce ment on physical properties and resistance to sulfate attack, freezing and thawing, and al kali silica reactivity ACI Materials Journal March-April 1993 Kasai, Y. E, (1985) Studies into the Reuse of Demolished Concrete in Japan, Reuse of Concrete and Brick Materials, Pro ceedings II, EDA/RILEM Demo-Recycling Conference, Rotterdam, European Demolition A ssociation, the Netherlands. In Lamond, J.F. et al, Removal and Reuse of Harden ed Concrete ACI comm ittee 555 report March 2001 Kuennen Tom (2007) Waste Aggregat es Rock Products March 2007 Issue Kuennen Tom (2007) The economics of Recycling Rock Products October 2007 Issue Kuennen Tom (2008) Green Highways now part of complete package Better Roads Magazine February 2008 Issue Kuo, S.S, Mahgoub, H. S. and Ortega, J.E. (2001) Use of Recycled Concrete Made with Florida Limestone Aggregate for a Base Course in Fl exible Pavement. Florida Department of Transportation Final Report for Contract BC 409, State Materials Office, Gainesville, FL. Lamond, J.F. et al, Removal and Reuse of Hardened Concrete ACI committee 555 report March 2001 Malhotra, V. M, (1976), Use of Recycled Conc rete as a New Aggregat e Report 76-18, Canada Center for Mineral and Ener gy Technology, Ottawa, Canada. Marcia J. Simon, Warren H. Chesner, T Ta ylor Eighmy and Howard Jungedy K. National Research Project on Recycling in Highway Construction Public Roads July/August 2000 Mehta, P. K., and Monteiro, P. J. M. (2006) Concrete: Microstructure, Properties, and Materials, McGraw-Hill College Custom Series, pp. 264 & pp 276. Mukai et al., (1979) Study on Reuse of Waste Concrete for Aggregate for Concrete, Paper Presented at a Seminar on Energy and Resources Conservation in Concrete Technology, Japan-U.S. Cooperative Science Program, San Francisco, Calif. In Lamond, J.F. et al, Removal and Reuse of Hardened Conc rete ACI committee 555 report March 2001 Nabil Hossiney, (2008) Concrete containing recycled asphalt pavement for use in concrete pavement, Masters Thesis of University of Florida, Gainesville. National Cooperative Highway Research Progr am (NCHRP) Report 598 [Internet] [updated 2008 April 14; cited 2009 March 6]. Available from: http://onlinepubs.trb .org/onlinepubs/nch rp/nchrp_rpt_598.pdf

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103 S. Nagataki, A. Gokce, T. Saeki, Effects of recycled aggregate characteristics on performance parameters of recycled aggregate conc rete, Proceedings of Fifth CANMET/ACI International Conference on Durability of Concrete, Barcelona, Spain, June 2000, pp. 5171. Saeed A., Hammons I.M., Reed L.J, (2007) Comprehensive evaluation, design, and construction techniques for airfield Recycled concrete aggregate as unbound base Paper 07-3263, Transportation Research Board (2007) Sergenian J. T. (1996) The Use of Recycled A ggregates in the Construction of Portland Cement Concrete Pavement Masters Thesis of University of Florida, Gainesville. Schulz, R. R. (1988) Concrete with recycled rubble-developments in West Germany. In Y. Kasai (ed.) Rilem: Reuse of demolition waste, 500-509. Chapman and Hall, London. Rasheeduzzafar, K. A. (1984), Recycled Concre te-A Source of New Aggregates, Cement, Concrete, and aggregates, V.6, No.1, pp. 17-27. "Recycling Concrete Pavement," Concrete Pavi ng Technology, TB-014P, American Concrete Pavement Association, Skokie, Illinois, 1993. Richardson, B. J. E., and Jordan, D. O. (1994) Use of recycled concrete as a road pavement material within Australia 1994. Proceeding of the 17th ARRB Conference, Part 3, 17(3), pp 213-228. Smith J. T, Tighe S. L. Recycled Concrete Aggregates Coefficient of Thermal Expansion: Characterization, Variability, Impact on Performance Paper 09-2196, Transportation Research Board 2009 Sri Ravindrarajah, R. and Tam, C. T., (1985) Recycled Concrete as Fine and Coarse aggregates in Concrete Magaziine of concrete Research. Vol.39, No. 141, pp. 214-220. In ChuangTsair S. (1989) Recycled Portland Cement Concrete as Aggregate for New Concrete Pavements Masters Thesis of University of Florida, Gainesville. Tia, M., Bloomquist, D., Alungbe, G.D., and Ri chardson, D., 1991, Coefficient of Thermal Expansion of Concrete Used in Florida, Research Report, University of Florida. Tia, M., Wu, C.L., Ruth, B.E., Bloomquist, D ., and Choubane, B., 1989, Field Evaluation of Rigid Pavement Design System--Phase IV, Re search Report, University of Florida, August. Von Stein, E. L. (1993), Construction and demolit ion debris. In H. F. Lund (ed.) the McGrawHill recycling handbook, 20.1-20.19. McGraw-Hill, New York. Wilburn, D. R. and Goonan, T. G., (1998) A ggregate from Natural and Recycled Sources, Economic Assessment of Construction Appli cations A Materials Flow Analysis.

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104 United States Geological Survey Circular 1176, United States Department of Interior, Washington, DC (1998) 37 pp.

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105 BIOGRAPHICAL SKETCH Patrick Amoah Bekoe was born in 1979 at Koforidua, Ghana. He attended the Kwame Nkrumah University of Science and Technol ogy from September 1998 to June 2002 where he earned his Bachelor of Science degree in ci vil engineering in Marc h 2003. He was employed with the Department of Feeder roads under the Ministry of Transportation from October 2003 and was awarded the Ministry of Transportation Fe llowship to pursue his masters degree in civil engineering at the University of Florida in sp ring 2008. He graduated from the University of Florida in summer 2009. He was awarded the gra duate school fellowship by the University of Florida to pursue a PHD in civil engineering.