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Development and Evaluation of Permeable Friction Course Mix Design for Florida Conditions

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Title:
Development and Evaluation of Permeable Friction Course Mix Design for Florida Conditions
Copyright Date:
2008

Subjects

Subjects / Keywords:
Asphalt ( jstor )
Databases ( jstor )
Design evaluation ( jstor )
Film thickness ( jstor )
Granite ( jstor )
Limestones ( jstor )
Minerals ( jstor )
Ovens ( jstor )
Specimens ( jstor )
Surface areas ( jstor )

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Source Institution:
University of Florida
Holding Location:
University of Florida
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All applicable rights reserved by the source institution and holding location.
Embargo Date:
7/30/2007

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DEVELOPMENT AND EVALUATION OF PERMEABLE FRICTION COURSE MIX
DESIGN FOR FLORIDA CONDITIONS

















By

LOKENDRA JAISWAL


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF ENGINEERING

UNIVERSITY OF FLORIDA


2005

































Copyright 2005

by

Lokendra Jaiswal

































This document is dedicated to my parents.















ACKNOWLEDGMENTS

I wish to specially thank Dr. Bjorn Birgisson and Dr. Reynaldo Roque for their

guidance and understanding throughout the project. I believe that their technical

knowledge and personal advice helped me to achieve this milestone in my life and career.

I really appreciate advice I received from Georg Lopp throughout my research

work and for making thing work in laboratory.

Thanks go to Dr. Christos Drakos, Georg Lopp and Greg Sholar for reviewing

Performance Test Database (P.T.D.) software and making helpful suggestions, and also

to the anonymous referees for many insightful comments.

I would like to thank Alvaro and Tung for their assistance in performing various

laboratory tests. I would like to thank Greg Sholar and Howie Mosely from the FDOT

research wing for their help during the course of the project.

Thanks go to Jaeseung, Sungho and Jianlin for there suggestion in finite element

analysis.

I would like to thank all my friends for providing an unforgettable and enjoyable

time during my two years of study in Gainesville. Finally, I would like to thank my

parents and my aunt and uncle for all the love and support they have given me throughout

my academic years.
















TABLE OF CONTENTS

page

A C K N O W L E D G M E N T S ................................................................................................. iv

L IST O F T A B L E S ........................................................................... ........... ix

LIST OF FIGURES ......... ........................................... ............ xi

A B S T R A C T .........x.................................... ....................... ................. xv

CHAPTER

1 IN TR OD U CTION .............................. ...... .. .... .. ......... ................

1.1 B ack g rou n d .................................................................................. 1
1 .2 O b je ctiv e s ................................................... ................ .. 2
1.3 Scope ................. ................ ................................. .........2
1.4 R research A approach ......................................................... ................ ..... 3

2 DEVELOPMENT OF MIX DESIGN PROCEDURE FOR POROUS
FR IC T IO N C O U R SE .............................................................. ....................... 5

2.1 Initial Study and O bjectives................................................... ................. ..5
2.2 Georgia PEM Mixture Design as per GDT 114 Test Method: B (1996).....6
2.3 Overview of Evaluation of Preliminary OGFC/PFC Mix design
Procedure Developed by Vardhan (2004)......................... .....................9
2.3.1 Determination of Compaction level for PFC..............................9
2.3.2 OGFC/PFC Mixture Design Procedure Proposed By Varadhan
(2004) .................. ......... ....... ........ .........12
2.3.3 Long-Term Oven Aging Procedure Proposed for PFC Mixture
by V aradhan (2004) ......................... .......... .... ................ ... 14
2.4 Verification of Florida Permeable Friction Course Mixture Design .........15
2 .4 .1 M materials ............................................. ................ 15
Aggregate and gradation selection.............................. .. .....15
B inder and m ineral fiber ......................................... .................... 16
2.4.2 Sample Preparation for Determination of Optimum Asphalt
C ontent ............... ...... ....... ........ ... ......... .... ... .. ........ 17
2.4.4 Mixing and Compaction of Samples for Determination of Bulk
Specific c G gravity ........................................................ .. ... 18
2.4.4 Determination of Optimum Asphalt Content.............................20









2.5 Evaluation of Film Thickness Criterion in PFC Design............................24
2.5.1 Review of Asphalt Film Thickness Calculation Methods .............27
2.5.2 Comparison of Results Obtained from Each Film Thickness
C alculation M ethod ............. .... ......... ........................................34
2.5.3 Relative Minimum Film Thickness Requirement........................36
2.6 Recommended Specification for PFC Mixture Design ...........................39
2.7 Conclusion of Verification of PFC mixture Design Procedure .................44

3 EVALUATION OF 1-295 PFC MIX DESIGN............................................. 45

3 .1 O bj e ctiv e ............ .. ............. ......... .... .......... ................ 4 5
3.2 Scope of Project ......... .. ...................................... ..... .... .. ........ .... 45
3.3 M materials used for 1-295 PFC project................................ ... ..................46
3.3.1 Aggregate and Hydrated Lime................................................. 46
3.3.2 Binder and M ineral Fiber................................... ............... 46
3.4 L location of Project...................... .. ............................. ... .......... ..... 48
3.5 Specification and Hypothesis U sed ................................. ............... 49
3.6 Determination of Optimum Asphalt Content........................................50
3.6.1 M ixing and Com action ..................................... ............... ..51
3.6.2 A sphalt Film Thickness ...................................... ............... 55
3.7 Superpave IDT Performance Test Results................................................55
3.7.1 Superpave Indirect Test Results and Analysis.............................. 57
3.8 Analysis of Fracture Result Based on Interstitial Volume and
Aggregate Interaction.................... ..........................60
3.8.1 Determination of Porosity and Interstitial Volume.....................61
3.8.2 Analysis and Conclusion............................. ................ ..............63
3.9 Verification of Locking Point of Selected Gradation for 1-295 PFC
P roje ct ................. ........... ......... .. .. ............................. ............. 6 5
3.10 Summary and Conclusion .................... .. .................. ............... 65

4 A PROPOSED NEW FRACTURE TEST FOR ASPHALT MASTIC.................67

4 .1 P u rp o se an d N eed ........................................................... ....................67
4.2 Background ............... ............................. .. .................. .............. 67
4.3 Specim en and Test D evice D esign .................................................... .... 68
4.4 Formulation of Tensile Force Transfer from Wedge to Specimen............71
4.5 Verification of Stress States within Loaded Specimen..............................74
4.6 Sample Preparation Guidelines...................... ..... ....................78
4.7 Recommendation for Further Development ...........................................81

5 PERFORMANCE TEST DATABASE (PTD)........................... .....................82

5 .1 P re fa c e ..................................................... ................ 8 2
5.1.1 Package Inform ation ........................................... ............... 82
5.1.2 System Requirements.............. ........ ...............83
5.1.3 Supported Output Format Requirement ............... .....................83
5.2 Program O verview ........................ .. ............ ................... ............... 84









5.2.1 Database Storage Outline................... ............... 86
5.2.2 Software Coding Architecture and Program Flow ......................87
5.3 Installation.................................... ........................................ 88
5.4 U ser's M annual ................................................................ .. ....... ..... 89
5.4.1 Interaction to All Interfaces of Database ................. ................89
5.4.2 B utton Function ........................................ ......... ............... 90
5.4.3 D ata Entry ......... ................................. ......... ...91
5.4.4 Navigation through Input Templates and Database.......................97
5.4.5 D ata transfer to D atabase............... ..............................................97
5.4.7 R report G eneration.................................... ........................ 102
5.4.8 Repair and R em ove Program ...................................................... 103
5.5 Sum m aries and Recom m endation...........................................................103

6 MOISTURE CONDITIONING ON 1-295 PFC PROJECT .............................105

6 .1 O bj ectiv e ............................................................................ 10 5
6 .2 S co p e ......................................................... ......................... 10 5
6.3 Materials and Methodology ............................................................106
6.3.1 Aggregate and H ydrated Lim e....................................................106
6.3.2 Binder and M ineral Fiber.................................. ............... 106
6.4 Specim en Preparation and Testing....................................................... 107
6.4.1 Mixing and Determination of Asphalt Content .........................108
6.4.2 V olum etric Properties .............. ......... ...................................109
6.4.3 Moisture Conditioning and Testing ............................................109
6.5 Fracture Test on M oisture condition.................................... ............... 112
6.5.1 Findings and Analysis..... .......... ....................................... 113
6.6 Sum m ary and Conclusion .............................................. .................. 117

7 SUPERPAVE IDT FRACTURE TEST RESULTS ............ ...............118

7 .1 M materials .............. .... .................. ...................... ............... 1 18
7.1.1 Aggregate and Hydrated Lime...............................................118
7.1.2 B inder and M ineral Fiber............................................................119
7.2 Test M ethod .................. .......................... .. .... .. .. .......... .... 120
7.2.1 Sample Preparation .......... ................................. ..............120
7.2.2 Testing Equipm ent................. .............................................. 121
7.2.3 Specimen Preparation and Testing Procedure ...........................123
7.2.4 Test Procedures and Analysis of Test Results.............................124
7.2.5 Results of Fracture Testing on PFC Mixtures..............................131
7.3 Summary and Conclusion .............................................. .................. 139

APPENDIX

A SAMPLE CALCULATION OF VOLUMETRICS FOR GPEM AND PFC
M IX T U R E ....................................................... .............. 14 0









B MAIN PROGRAMMING CODE OF PERFORMANCE TEST DATABASE
(P .T .D .) ........................................................................ 1 4 5

C EFFECTIVE ASPHALT CONTENT CALCULATION FOR FILM
THICKNESS DETERM INATION ........................................ ............... 153

D GEOMERTIC DETAILS OF FRACTURE TEST SPECIMEN AND MOLDS
FOR ASPHALT M ASTIC.......................... ....................................... ... 155

E VOLUMETRIC PROPERTIES OF MIXTURES ............................................161

F JO B M IX F O R M U L A ......... ................. .........................................................164

LIST O F R EFEREN CE S ... .... ............................................................ ............... 165

BIOGRAPHICAL SKETCH ...... ........ .. ................. .... ....................... 167
















LIST OF TABLES


Table Page

2-1 Gradation specifications according to GDT 114 (1996).........................................7

2-2 Locking Point Based on Gradient of Slope (Varadhan, 2004)..............................11

2-3 Locking Points of all Mixtures based on Gradient of Slope (Varadhan, 2004)....... 11

2-4 Composition of GPEM-Limestone gradation JMF ..............................................16

2-5 Composition of GPEM-Granite gradation JMF ............................ ............... 16

2 -6 M material qu entities ............................................................................... .. 2 0

2-7 Surface Area Factor Hveem (1991) .............................................. ............... 28

2-8 Surface area Factor suggested by Nukunya (2001) for coarse aggregate structure .29

2-9 Surface area factors for Interstitial Volume ............... ........................................31

2-10 C oreL ok calculation Sheet ............................................... ............................ 33

2-11 Comparison of Film Thickness method for Limestone mixture ............................35

2-12 Comparison of Film Thickness method for Granite mixture ................................ 35

2-13 JMF of Optimum gradation for Gradation limits as per GDT 114 (1996) ..............38

2-14 Minimum film thickness requirements for different set of Asphalt absorption.......39

2-15 Proposed Gradation and Design specifications for Florida Permeable....................40

2-16 Surface area factor as per Nukunya et al (2001) ............ ....................................43

2-17 Minimum Effective Film Thickness Requirements ...........................................43

3-1 JM F com position of Gradation (1)..................................... .......................... 47

3-2 JM F com position of G radiation (2) ................................................ .....................47

3-3 PFC Gradation Design Range from FDOT specification SECTION 337................49









3-4 Summary of Indirect Tensile Test performed on 1-295 PFC mixtures ....................58

3-5 Su rface area factors ......................................................................... ................... 63

3-6 Porosity for all the dominant aggregate size ranges (DASR) ................................64

3-7 Interstitial V olum e for different JM Fs ........................................ .....................64

3-8 Locking Point Based on Gradient of Slope..........................................................65

4-1 Part of fine aggregates to be mixed with total asphalt content (6%) of 1-295 PFC
p ro je ct ...................................... ................................................... 7 9

5-1 Buttons and there corresponding function .................................... ............... 91

6-1 Gradation of 1-295 PFC Project ................................ ......... ............... .. 106

6-2 Summary of fracture test on moisture condition sample compared with
unconditioned sam ple............ ... ...................................................... .. .... .. .. .... 115

7-1 Summary of Fracture Test results on Short-Term and Long-Term Oven Aged
Mixtures of Georgia PEM, PFC Project and OGFC Mixture .............................134

A-i Gradation for Georgia PEM-Granite............... ....................................140

A-2 Bulk Specific Gravity for Georgia PEM-Granite........................ ............... 140

A-3 Rice Test for Georgia PEM-Granite............................................. ...............141

A-4 Drain-down Test for Georgia PEM -Granite........................................................ 141

A-5 Film Thickness for Georgia PEM-Granite............ ................................142

C-1 Core-Lok Results calculation for Efffective asphalt content ..............................154

C-2 M inim um Film Thickness ............................................. ............................. 154

E-l Volumetric Properties of all the Mixtures..........................................................162

F-l Composition of Job Mix Formula of FC-5 Limestone ................ ................164

F-2 Composition of Job Mix Formula of FC-5 Granite ................................................164
















LIST OF FIGURES


Figure Page

1-1 Flow chart showing Research Approach implemented .......................................4

2-1 Gradation Band with in GDT 114 (1996) specified gradation limits used by
V aradhan (2004) ..................................................................... 13

2-2 Georgia's Permeable European Mixture gradation band.................................17

2-3 Example of determination of inconsistent optimum asphalt content...................18

2-4 Mix Design of OGFC with aggregate type: Limestone...........................22

2-5 Mix Design of OGFC with aggregate type: Granite.........................................23

2-6 Aggregate Structure for Coarse and Fine Mixtures (Nukunya et al. [2001]) ........25

2-7 (a) Granite with high film (Required against stripping) (b) Limestone with low
film thickness as compared with granite due to absorption................................34

2-8 Optimum Gradation Band for Calculating Minimum film thickness
require ent ........................................................................ 38

2-9 Proposed Gradation limits for Florida Permeable Friction Course Mixtures........41

3-1 Gradation of 1-295 PFC mixtures ........................................................ ....... 47

3-2 Project L location ............ ... ... ..... ................................... 48

3-3 Mix Design of PFC Gradation (1) with aggregate type: Granite ...................53

3-4 Mix Design of PFC Gradation (2) with aggregate type: Granite ...................54

3-5 A)Energy Ratio, B) Failure Energy, C) Failure Strain, D) DCSE, E) Creep
Compliance, F) Resilient Modulus, G) Strain Rate, H) Tensile Strength I)
C re ep R ate ..................................................... ................ 5 9

3-6 Curve showing interaction between contiguous aggregate sizes.........................61

4-1 Model showing Specimen along with bearings fitted on steel rods and wedge
in loading direction. ....................................... ............... .... ....... 68









4-2 Plan view showing geometry of specimen......................................................69

4-3 Front view showing geometry of specimen..................................... .................70

4-4 Testing Device used by Mindess & Diamond (1980) for SEM testing on
cem ent m ortar .......................................................................7 1

4-5 Static analysis of force transfer from Wedge to Steel rods (Wedge angle =
2 x 0 ) .............................................................................. 7 3

4-6 Specimen 2-D Model subdivided in to 15 surfaces ............................................75

4-7 Meshing of 15 sub surface with critical model line divided into 175 elements. ...76

4-8 Deflection of Specimen's 2-D Model subdivided. ..............................................76

4-9 Stress distributions along centerline of specimen Tensile stress is shown as
positive e ..............................................................................77

4-10 Stress distribution along circumference of steel pin................ ....... ...........78

4-11 Mold for preparing specimen for Fracture and SEM testing .................................80

4-12 Geometry of main base plate to which side plates are attached ............................80

5-1 Flow chart showing extraction and input sequence of Indirect Tensile Test
D ata ..............................................................................................8 5

5-2 Flow chart showing data input of Complex Modulus test ....................................88

5-3 Installation Screen ............ ........................................................................ .... 89

5-4 M ain Interaction Tem plate.......................................................... ............... 90

5-5 Input tem plate option s......................................... .............................................92

5-6 M S-DOS Base text file input template ...................................... ............... 93

5-7 Input dialog box ....................................... ................ .. ........ .... 94

5-8 Save changes dialog box .............................................. .............................. 95

5-9 Decision Box for clipboard changes. ............................... ............................... 95

5-10 A applied tensile stress input box .................................... ........................... ........ 96

5-11 D database M ain M enu ..........................................................................97

5-12 D database Input M ask............................................................................. ........ 98









5-13 (a) Correct state of input tables for data entry .....................................................98

5-13 (b) Incorrect state of input tables for data entry..............................................98

5-13 (c) Right click projected arrow for opening paste option ...............................99

5-13 (d) Dialog box: After selecting paste option. Opt 'Yes'.................................99

5-14 Search dialog box 'Select type of search' ....................................... ...............100

5-15 Search form ...................... ........ ................................ .......... 101

5-16 Search R result Form ........................................................................ .. 101

5-17 Report delivery option ......................... .................. ................. ............... 102

5-18 Em ail Report ............. .................. .. ....................... ......... 103

6-1 Plot of 1-295 PFC mixture's gradation .............. ......................................... 107

6-2 Mix Design of 1-295 PFC-Granite mixture......... ......................................111

6-3 Compacted pill rolled in 1/8" inch sample placed in vacuum chamber ............112

6-4 Vacuum Saturation of sample prior to moisture conditioning..........................112

6-5 Affect of conditioning over stone to stone contact of PFC mixtures ................114

6-6 Comparison of Fracture Test results A) Energy ratio, B) Fracture energy, C)
Tensile strength, D) Failure strain, E) DCSE, F) Creep compliance, G)
Resilient modulus, H) Strain rate, I)Creep rate.................................................. 116

7-1 Gradation Band of Georgia PEM and 1-295 PFC Project...............................119

7-2 ID T testing device .................. ............................. .. ...... .. ........ .... 122

7-3 Tem perature controlled cham ber ................................... ................................... 122

7-4 Typical Dense-Graded specimen with extensometers attached ...........................123

7-5 D ehum idifying cham ber ............................................ .............................. 124

7-6 Power M odel for Creep Compliance ....................................... ............... 129

7-7 FE and D CSE from Strength Test.................................... ........................ 131

7 -8 E n ergy R atio ...................................................................... 13 5

7-9 Fracture Energy.............................. ......... ..... .... ... .............. 135









7-10 Failure Strain ......... .. ..................................................................................136

7 1 1 D C S E .............................................................................1 3 6

7-12 Resilient M odulus ..................................... ........ .. ................. 137

7-13 C reep C om pliance.......... .............................................................. .. .... .. .... .. 137

7-14 Strain R ate......................................................138

7-15 Power Model Parameter (D) .......... ............... ........................... 138

7-16 Power M odel Param eter (m) ............................................ ........................ .139

A-1 Final Mix Design for Georgia PEM-Granite ................................................144

D-1 Showing 3-D view of mold designed for preparing specimen for Asphalt
M astic ...................................... ...................................................156

D-2 Base plate 3-D wire view showing position of groves and notch........................157

D -3 B ase plate geom etry .......................................................................... 158

D -4 N otch plate 3-D w ire view .............................................................. ............... 159















Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Engineering

DEVELOPMENT AND EVALUATION OF PERMEABLE FRICTION COURSE MIX
DESIGN FOR FLORIDA CONDITIONS

By

Lokendra Jaiswal

August 2005

Chair: Bjorn Birgisson
Cochair: Reynaldo Ray
Major Department: Civil and Coastal Engineering

A mix design procedure for 'Permeable Friction Course' that provides guidance on

material properties, aggregate gradation, determination of optimum asphalt content, and

mixture properties is needed for Florida conditions. This project involves 1) development

of permeable friction course mix design procedure for Florida conditions, 2) evaluation

of permeable friction course of 1-295 project, 3) development of data extraction, analysis

and database software for material properties, indirect tensile test results, and complex

modulus test results, and 4) development of fracture test on sand asphalt for SEM

analysis and tensile strength. In the course of study an extensive literature review was

done on various mix design approach, material characteristics, and laboratory process

guideline.

Sample preparation and testing are carried in the laboratory for granite and

limestone aggregate permeable friction course for determination of optimum asphalt

content, moisture conditioning and long-term oven aging. An indirect tensile test is done









on specimen with optimum asphalt content to evaluate performance of mixture. Film

thickness, an important criterion for permeable friction course for ensuring resistance

against stripping and asphalt hardening, is developed, based on the different absorption

capacity of aggregate. This proposed mix design procedure was used to design PFC

mixture for the 1-295 project. Performance test database (PTD.exe) as data analysis and

data storage software was developed using visual basic as the programming language.

This software was used throughout the project for analyzing the test results and storing in

database for future reference. Based on analysis of fracture test results of the 1-295 PFC

project, essentiality of fracture test on sand asphalt came up. A framework of fracture test

on sand asphalt which can be conducted within SEM chamber is done. Observation of

fracture test results of moisture conditioned sample of 1-295 PFC mixture showed that

coarse stone to stone contact is affected due to conditioning. Creep response of mixture

remains approximately same after conditioning as compared with unconditioned sample.

Finally, specifications and mix design procedure for PFC mixture are

recommended and recommendations for further development of sand-asphalt fracture test

are provided. Fracture test results FC-5 granite and FC-5 limestone samples, both aged

and unaged, are compared with mixture designed for GPEM development and 1-295 PFC

project.














CHAPTER 1
INTRODUCTION

1.1 Background

Porous Friction Course (PFC) improves the frictional resistance of pavements,

along with the drainage of water, for reducing the potential of aquaplaning. In the 1990's

the traditional FC-2 friction course developed by Florida was replaced by coarser open

graded friction course (FC-5) which is 1/-inch Nominal Maximum Aggregate Size

(NMAS), placed approximately 34-inch thick. Even though the FC-5 had coarser

aggregate structure and additional water storage capacity as compared to the old FC-2,

water ponding on pavement surfaces continued to be a problem. Many states in US

developed porous friction courses to over come such problems.

The Georgia DOT developed their porous friction course design by utilizing a gap-

grading aggregate and lowering the percentage of filler, following European PFC mixture

designs. The combination of gap grading, low filler, and high asphalt content lead to the

draining of asphalt binder from mixture during transportation and lay down procedure.

Due to this problem, the Georgia DOT introduced mineral fibers in Georgia PEM

mixtures.

This research project is focused to develop and evaluate the Georgia PEM (GPEM)

mix design procedure for Florida conditions, and updating the GPEM mix design by

introducing Superpave gyratory compaction. Also, in the course of this project two other

important developments are accomplished. First, a Performance Test Database (PTD)

was developed to facilitate data analysis and data storage of mixture design and









performance test results. The second achievement is the preliminary design of a new

fracture test for asphalt mastic.

1.2 Objectives

The primary objectives of the research are summarized below:

* Open Graded friction course because of their macro texture and air voids may not
have enough water storage capacity for some applications, and may also be
susceptible to stripping. The rate of susceptibility depends on climatic conditions.
Therefore the development and evaluation of mix design procedure for Porous
Friction Course (PFC) for Florida Climatic Condition is main objective of this
research project.

* Mix design for a test strip on 1-295, containing a Porous Friction Course (PFC)
mixture design developed in this research project.

* Developing data analysis and database software, to store data from Fracture Test
and Complex Modulus Test.

* Developing basics framework of fracture test for asphalt mastic.

1.3 Scope

Mix design for 1-295 highway (PFC project) provides an excellent opportunity to

use and implement mix design procedure developed for GPEM. Database developed for

data analysis and data storage is an excellent tool for referring previous mixture

properties and their performance, while selecting gradation and doing mix design

.Fracture test done on various field and lab prepared mixes enlightens many factors

affecting the fracture resistance of mixtures. These factors are discussed individually in

this thesis. It is always assumed that coarse aggregate are mainly responsible for

contribution towards fracture resistance. Steps taken to develop fracture test on sand

asphalt provides view on the contribution of fines and binder towards fracture resistance.









1.4 Research Approach

A detailed literature review was performed previously by Varadhan (2004) to

understand Georgia's mix design procedure. Figure 1-1 shows a flow chart of the

approach adopted for this research. The Georgia DOT used Marshall's blow for mix

design of PFC. This research introduced the Superpave Gyratory Compactor. Therefore, a

primary objective was to determine number of gyration required to attain compaction

level same as field compaction. Second step was to determine film thickness

corresponding to this compaction level. Different methods of determining film thickness

are carried out and then most optimize method is selected for mix design procedure.

Superpave Indirect tensile test were carried out on Short Term Oven Aged (STOA) and

Long Term Oven Aged (LTOA) mixtures for determination of facture resistance.

Simultaneously, analysis and database software was developed in order to analyze and

store data from this project. Once the mix design procedure was finalized a section of I-

295 highway is designed based on this mix design method. Two trial gradations (JMF)

were selected with in control points and mix design was carried on both of these

gradations to determine optimum asphalt content. Final selection of gradation was done

based strength and energy ratio criteria. Fracture testing was carried on all STOA and

LTOA samples from US highways- 27 and 1-295 PFC project. In the course of the project

necessity of sand asphalt's fracture resistance lead to develop new fracture test.








4



Research Approach





work done and finalizing objectives to
be achieved.


1-295 PFC prjct ad G C sap
1-295 PFC project and G3PFC samples


1-1. Flow chart showing


of Performance Test


S Data Extraction and Analysis


Analyzed data stored in database
------- ------ -- --------- -




Data


references


- d + ,-


- - !e erenCe 0 aLta ase
during Mix design
Data input



Development of
fracture test on asphalt





-ch Approach implemented


Development and evaluation of mix design procedure of
GPEM for Florida Condition.
---------------------------------------
Detennination of Compaction Level


----------------- --------------
.::::..:::::::::::::I:::::::::::::::::::
Development Thickness Criterion


Determination of aging of Fracture Test
-- - - - - :


Mix Design of Porous Friction Course (1-295 PFC based
performance test
r ------------------------------------
Selection of two trail gradation


I Mix Design


SIndirect T Test
... ... .. ... .. ... ... ... ... ... ... ... ... ... ... ... .. .. ... .. ... ... ... ... ... ... ... ... ... ... ... ... ... .. ...


I














CHAPTER 2
DEVELOPMENT OF MIX DESIGN PROCEDURE FOR POROUS FRICTION
COURSE

2.1 Initial Study and Objectives

The Georgia Department of Transportation started evaluation of Porous European

Mix (PEM), a form of Porous Friction Course Mixture, in 1992 for development a mix

design for Porous Friction Course (PFC), which is entitled for Georgia Permeable

European Mixture. Georgia PEM mixtures proved to be more permeable than

conventional OGFC, due to its gap-graded characteristics, with a predominant single size

coarse aggregate fraction that contains high percentage of air voids as specified by

Watson et al. (1998). The Georgia PEM mix design (GDT 114, 1996) was used as a

starting point for the new Florida Permeable Friction Course (PFC) mixture design. In

the following, the GPEM mixture design developed by the Georgia DOT will be

reviewed briefly, followed by the development of a new Florida PFC mixture design,

which is based on the GPEM mixture design.

Main objective of the 'Permeable Friction Course Design' is to design a highly

permeable mixture with good durability characteristics, while also providing sufficient

mixture stability through coarse stone to stone contact. In order to enhance durability, it is

desirable to have a high asphalt content, while preventing the drain down of binder, thus

providing sufficient binder film thickness. Once the coarse aggregate contact structure is

chosen, the design asphalt content is obtained by selecting four (4) trial mixtures of

varying asphalt contents, and choosing the asphalt content that results in a minimum









VMA. This is done to ensure reasonably high asphalt content. Importantly, it is

necessary to use four trial asphalt contents, rather than three. Choosing only three asphalt

contents will always result in one of the chosen asphalt contents to show a minimum,

whereas choosing four asphalt contents will result in a true minimum that can be verified.

The objectives of this chapter is to develop a Porous Friction Course (PFC) mixture

design for Florida conditions and materials using the Superpave gyratory compactor, and

to evaluate the new PFC mixture design using two mixtures that contain aggregates and

asphalt that are typical to Florida. The Georgia PEM mixture design is used as a starting

point for the development of the Florida PFC mixture design.

2.2 Georgia PEM Mixture Design as per GDT 114 Test Method: B (1996)

In the following the Georgia DOT GPEM mixture design will be reviewed and used as a

starting point for the Florida PFC mixture design approach. The first and foremost

change was the introduction of the Superpave gyratory compaction into the mixture

design in lieu of the Marshall compaction used by Georgia DOT. The main elements of

the Georgia PEM mixture design are as follows:

* Georgia DOT GPEM mixture design method (GDT-114 Test Method: B, 1996)
specifies the use of modified asphalt cement (PG 76-22) as specified in Section 820
(GDT 114,1996) and does not require the determination of surface capacity (KC) to
determine initial trial asphalt contents.

* The Georgia DOT uses the Marshall Method of compaction during the design of
the Georgia PEM mixtures.

* A stabilizing fiber is added to mixture for avoiding binder drain down, which meets
the requirement of Section 819 (GDT 114, 1996).

In the following, the steps in the Georgia PEM mixture design (GDT-114 Test

Method: B, 1996) are listed. Table 2-1 shows gradation limits as GDT 114 (1996).

A. SCOPE OF GPEM MIXTURE DESIGN









The Georgia DOT method of design for a modified open graded bituminous GPEM

mixture consists of four steps. The first is to conduct a modified Marshall mix design

(AASHTO T-245) to determine asphalt cement content. The second step is to determine

optimum asphalt content. The third step is to perform a drain down test, according to

GDT-127 (2005), or AASHTO T 305-97 (2001). The final step is to perform a boil test,

according to GDT-56, or ASTM D 3625. Table 2-1 gives gradation limits and design

requirement for Open Graded Friction Course (For 9.5 mm and 12.5 mm Gradation) and

Permeable European Mixture (12.5 mm Gradation). Gradation limits specified for 12.5

GPEM are used as design limits for development of PFC mix design for Florida Design.

There are no mixture design guidelines currently available for the determination of trial

gradations within the specification limit. Rather, the mixture designer has to use his own

judgment to determine a trial gradation within the limits provided.

Table 2-1. Gradation specifications according to GDT 114 (1996)


Mixture
Control 12.5 mm
Tolerance Asphalt Concrete PEM
Grading Requirements
S0.0 3/4 in (19 mm) sieve 100
S6.1 1/2 in (12.5 mm) sieve 80-100
+ 5.6 3/8 in (9.5 mm) sieve 35-60
+5.7 No. 4 (4.75 mm) sieve 10-25
+4.6 No.8 (2.36 mm) sieve 5 10
+2.0 No. 200 (75 tm) sieve 1-4
Design Requirement
+0.4 Range for % AC 5.5-7.0
Class of stone (Section 800) "A" only
Coating retention (GDT-56) 95
Drain-down, AASHTO T 305 (%)<0.3


B. APPARATUS









The apparatus required shall consist of the following:

1. Drain-Down equipment as specified in GDT-127 (2005) or AASHTO T 305-97
(2001)
2. Marshall design equipment as specified in AASHTO T-245
3. Boil Test Equipment as specified in GDT-56 (2005) or ASTM D 3625
4. Balance, 5000 grams Capacity 0.1 grams accuracy.

Step 2 Modified Marshall Design and Optimum AC

After determining a trial aggregate blend the following steps are required to

determine the asphalt content:

1. Heat the coarse aggregate to 3500F 3.5F (176C 2.5 o C ), heat the mould to
300oF 3.5 0 F (1480 C 2.5 0 C) and heat the AC to 330 o F 3.5 0 F (1650 C 2.5
o C).

2. Mix aggregate with asphalt at three asphalt contents in 0.5 % interval nearest to the
optimum asphalt content establishes in step 1. The three specimens should be
compacted at the nearest 0.5% interval to the optimum and three specimens each at
0.5% above and below the mid interval.

3. After mixing, return to oven if necessary and when 320oF 3.50F (1600 C 2.5 0
C) compact using 25 blows on each side

4. When compacted, cool to the room temperature before removing from the mold

5. Bulk Specific Gravity: Determine the density of a regular shaped specimen of
compacted mix from its dry mass (in grams) and its volume in cubic centimeters
obtained from its dimensions for height and radius. Convert the density to the bulk
specific gravity by dividing by 0.99707 g/cc, the density of water at 250C

Bulk Sp.Gr = W / (7 r2h/ 0.99707)
= Weight (gms) x 0.0048417/Height (in)
W = Weight of specimen in grams
R = radius in cm
H = height in cm
6. Calculate percent air voids, VMA and voids filled with asphalt based on aggregate
specific gravity

7. Plot VMA curve versus AC content

8. Select the optimum asphalt content at the lowest point on VMA curve









Step 3 Drain-Down Test

Perform the drain test in accordance with the GDT 127 (2005) (Method for

determining Drain Down characteristics in Un-compacted Bituminous Mixtures) or

AASHTO T 305-97 (2001). A mix with an optimum AC content as calculated above is

placed in a wired basket having 6.4 mm (1/4 inch) mesh openings and heated 14C (25F)

above the normal production temperature (typically around 350F) for one hour. The

amount of cement, which drains from the basket, is measured. If the sample fails to meet

the requirements of maximum drain down of 0.3%, increase the fiber content by 0.1%

and repeat the test.

Step 4 Boil Test

Perform the boil test according to GDT 56 (2005) or ASTM D 3625 with

complete batch of mix at optimum asphalt content as determined in step 2 above. If the

sample treated with hydrated lime fails to maintain 95% coating, a sample shall be tested

in which 0.5% liquid anti stripping additive has been used to treat the asphalt cement in

addition to the treatment of aggregate with hydrated lime.

2.3 Overview of Evaluation of Preliminary OGFC/PFC Mix design Procedure
Developed by Vardhan (2004)

Varadhan (2004) introduced the Superpave gyratory compaction into PFC mixture

design in lieu of the Marshall compaction used by Georgia DOT. The study used to make

the specified changes in preliminary mix design approach and the development of long-

term aging procedure for compacted PFC mixture are discussed in the following.

2.3.1 Determination of Compaction level for PFC

The Georgia DOT prepares specimen using the Marshall Hammer with 25 blows

on each side of the specimen. Due to the overall strong desire by both the FDOT and the









University of Florida researchers to use a compaction procedure that is more in line with

current mix design compaction procedures in America, it was decided to use the

Superpave gyratory compactor for compacting the specimens. Based on the work

performed by Varadhan (2004) it was determined that an appropriate compaction level of

50 gyrations was sufficient to compact OGFC mixtures. This determination was based

on a modified locking point concept (Vavrik & Carpenter, 1998). The approach by

Vavrik (1998) was developed for dense graded mixtures. Varadhan (2004) found that the

use of the locking point concept by Vavrik & Carpenter (1998) resulted in a severe over

compaction of OGFC mixtures, leading to aggregate breakdown. Therefore, the locking

point concept was modified for use in OGFC mixtures, as described by Varadhan (2004).

As determined by Vardhan (2004) the compaction curve for OGFC/PFC mixtures

follows a logarithmic trend. To identify the locking point, the rate of change of slope of

compaction curve was used. The stage, at which the rate of change of compaction was

insignificant, is the point of maximum resistance to compaction. Thus, using the

logarithmic regression of the compaction data, the rate of change of slope can be obtained

as follows:

y = m ln(x) + c

Rate of compaction = dy/dx = m/x (at any x=N)

Rate of change of slope of compaction curve = d2y/dx2 = -m/ x2 (at any x =N)

Based on the above idea the locking point was identified as the point at which two

gyrations at same gradient of slope were preceded by two gyrations at same gradient of

slope. The gradient was taken up to four decimal places, as shown in Table 2-2 for FC-5

Granite (Varadhan, 2004). The reason this was chosen as locking point was based on the









fact the change in air voids was insignificant at this stage and that this trend was

consistently observed in all the mixtures. In addition, the compaction level as identified

from visual observation was around 50-60. Thus, based on the above study, the locking

points for theses mixtures were identified as shown in Table 2-3

Table 2-2. Locking Point Based on Gradient of Slope (Varadhan, 2004)

FC-5 Granite
# of Gyrations Gradient of slope
39 0.0018
40 0.0017
41 0.0016
42 0.0015
43 0.0014
44 0.0014
45 0.0013
46 (LP) 0.0013
47 0.0012
48 0.0012
49 0.0011
50 0.0011

Table 2-3. Locking Points of all Mixtures based on Gradient of Slope (Varadhan, 2004)

Mixtures Locking Point
FC-5 Limestone 56
FC-5 Granite 46
NOVACHIP 50

Thus based on above concept the locking points for FC-5 with Limestone, FC-5

with Granite and NOVACHIP were 56, 46 and 50 respectively. The specimens were

compacted again to these gyrations and extraction of asphalt was performed to observe

the gradations after compaction.

For FC-5 Lime even when the gyrations were reduced to 56 from 125, the same

amount of breakdown was observed. This clearly indicated that in case of limestone, the

breakdown occurred in the initial stages itself i.e. at very low gyrations. Hence, even if









the gyrations were to be further reduced, the breakdown was still going to persist. For

FC-5 with granite and NOVACHIP, the gradation looks nearly the same as that of the

original gradation. In addition, the air voids for FC-5 Granite and NOVACHIP were

around 21 % and 15 % respectively, which is typical for these open graded mixtures.

Thus, from the above the study it is clear that, though the locking point of each of

these mixtures differed slightly from each other, it was around 50 gyrations. This was

further corroborated by the study done by NCAT on the compaction levels of friction

courses. NCAT suggests 50 gyrations as compaction level for all friction courses.

Thus based on this study from visual observation and rate of change of compaction,

NCAT study for friction course, Varadhan (2004) stated that 50 gyrations should be the

compaction level for friction course mixes.

2.3.2 OGFC/PFC Mixture Design Procedure Proposed By Varadhan (2004)

Use of modified asphalt cement does not require determination of surface capacity

(Kc) as per GDT 114 Test method: B (1996). Boil test is not included in proposed mix

design of PFC as a modified asphalt cement PG76-22 with 0.5% anti strip agent is used.

The gradation band used by Varadhan (2004) with in GDT 114 (1996) specified

gradation limits (Ref. Table 2-1) is shown in Figure 2-1.

Following is the method developed and proposed:

Modified GDT 114 test method: B by Varadhan (2004)

1. Heat the coarse aggregate, the mould to 350 o F 3.5 o F (176 o C 2.5 o C) and the
AC to 330 oF 3.5 oF (1650 C 2.5 o C)

2. Mix aggregate with asphalt at three asphalt contents, viz., 5.5%, 6% and 6.5%. Just
before mixing, add the required amount of mineral fibers to the aggregate. Prepare
three samples at each of the asphalt content

3. After mixing, return to oven for two hours for STOA at 320 F 3.5 F (1600 C +
2.5 o C). Then compact using the Superpave Gyratory Compactor 50 gyrations










4. When compacted, cool to the room temperature before removing from the mold. It
typically takes 1 hour 45 min to cool down.

5. Bulk Specific Gravity: Determine the density of a regular shaped specimen of
compacted mix from its dry mass (in grams) and its volume in cubic centimeters
obtained from its dimensions for height and radius. Convert the density to the bulk
specific gravity by dividing by 0.99707 g/cc, the density of water at 25 C


Gradation Band by Vardhan (2004)



100
S-90
3 80
70
S60
S50-
40
30
S20
0
No No No No No No No 3/8" 1/2" 3/4
200100 50 30 16 8 4
Sieve Sizes

-- Max Control Points -- Min Control Points

Figure 2-1. Gradation Band with in GDT 114 (1996) specified gradation limits used by
Varadhan (2004)

6. Bulk Sp.Gr = W / (n r2h/ 0.99707) = Weight (gms) x 0.0048417/Height (in)

7. W = Weight of specimen in grams

8. R= radius in cm

9. H= height in cm

10. Calculate percent air voids, VMA and voids filled with asphalt based on aggregate
specific gravity

11. Plot VMA curve versus AC content

12. Select the optimum asphalt content at the lowest point on VMA curve









Drain-Down Test

Perform the drain test in accordance with the GDT 127 (2005) or AASHTO T

305-97 (2001). A mix with an optimum AC content as calculated above is placed in a

wired basket having 6.4 mm (1/4 inch) mesh openings and heated 14 C (25 F) above the

normal production temperature (typically around 350F) for one hour. The amount of

cement, which drains from the basket, is measured. If the sample fails to meet the

requirements of maximum drain down of 0.3 %, increase the fiber content by 0.1 % and

repeat the test.

It is recommended by GDOT that the asphalt content should not be below 6%

because of coating issues. The film thickness requirement for granite mixture as per

Georgia DOT is 27 microns.

Moisture Damage Test

Perform the moisture damage test in accordance with AASHTO T-283 (2003) on

compacted specimen. The specimens are rolled in 1/8" wire mesh which are kept in

position using two clamps on either edges of pills for avoiding fall down at high

temperature of 60C (140oF).

2.3.3 Long-Term Oven Aging Procedure Proposed for PFC Mixture by Varadhan
(2004)

In order to evaluate the mixture susceptibility to aging, it was necessary to develop

a modified long-term aging procedure that was based on AASHTO PP2 (1994). Since

these mixtures are very course and open, there is a possibility of these mixes falling apart

during aging. Hence, a procedure was developed to contain the compacted pills from

falling apart during aging.

S A 1/8" opening wire mesh is should be rolled around pills, with two clamps
tightened at 1-inch distance from each end of the pill. The mesh size is chosen in









order to ensure that there is good circulation of air within the sample for oxidation
and at the same time, to prevent the smaller aggregate particles from falling off
through the mesh.

* Specimens are kept in ovens with porous plate at bottom for 1850 F 5.4 F (850 C
3 C) for 120 + 0.5 hours.

* After that time period, turn off the oven and open the door. Allow the oven and
specimen to cool to room temperature for about 16 hours.

2.4 Verification of Florida Permeable Friction Course Mixture Design

2.4.1 Materials

Aggregate and gradation selection

An existing Georgia PEM gradation obtained from the Georgia DOT was used as a

starting point in the mixture design. Figure 2-2 shows the gradation for the Georgia PEM.

Interestingly, the Georgia DOT mixture design follows the middle of the specified

gradation band on the coarse side, transitioning to the maximum allowable fines content

on the fine side. This selection of gradation will likely result in a good coarse aggregate

to aggregate contact structure, as well as ensuring the highest possible amount of asphalt

binder in the mixture, without significant drain down. Two types of aggregate are used

for this development i.e. Granite and Limestone. Nova Scotia granite and oolitic

limestone from South Florida (White Rock) were used for preparing the mixtures. The

same JMF is used for both granite and limestone mixture composed of aggregates from

different stockpiles. The Job mix formula for the granite was composed of aggregates

from stockpiles #7, #789 and Granite Screens. The job mix formula for the limestone was

composed of aggregates from stockpiles S1A, S1B and limestone screens. Hydrated lime

(1% by weight of aggregate) was used as anti-stripping agent for the granite aggregates.

All aggregates were heated to 3500F 3.5F (1760 C 2.5 o C) as specified in GDT 114









Test Method: B Section C (1996). Table 2-4 and Table 2-5 shows composing of GPEM-

limestone and GPEM-garanite job mix formula.

Table 2-4. Composition of GPEM-Limestone gradation JMF
Type S1A S1B Scrns JMF Control Points
% Amount 55.56 37.37 7.07 100 Max Min
Sieve SizeSizeA0.45
37.5 5.11 100 100 100 100
25 4.26 100 100 100 100
19 3.76 100 100 100 100 100 100
12.5 3.12 82 100 100 90 100 80
9.5 2.75 28 99 100 60 60 35
4.75 2.02 3 39 99 23 25 10
2.36 1.47 2 8 70 9 10 5
1.18 1.08 2 3 54 6
0.6 0.79 1 1 40 4
0.3 0.58 1 1 30 3
0.15 0.43 1 1 13 2
0.075 0.31 1 1 2 1 4 1

Table 2-5. Composition of GPEM-Granite gradation JMF
#789 Granite
Type #7 Granite Screens Lime JMF Control Points
% Amount 55 37 7 1 100 Max Min
Sieve SizeSizeA0.45
37.5 5.11 100 100 100 100 100
25 4.26 100 100 100 100 100
19 3.76 100 100 100 100 100 100 100
12.5 3.12 82 100 100 100 90 100 80
9.5 2.75 28 99 100 100 60 60 35
4.75 2.02 2 39 99 100 23 25 10
2.36 1.47 2 6 69 100 9 10 5
1.18 1.08 2 2 46 100 6
0.6 0.79 1 1 30 100 4
0.3 0.58 1 1 17 100 3
0.15 0.43 0 1 7 100 2
0.075 0.31 0 0 1 100 1 4 1


Binder and mineral fiber


SBS modified PG 76-22 asphalt, with 0.5% anti strip agent was used in the mixture

design. Mineral fiber (Fiberand Road Fibers) supplied by "SLOSS Industries, Alabama",










0.4% by weight of total mix, was added to mix in order to avoid binder drain drown.

Chemical composition of the mineral fiber is Vitreous Calcium Magnesium Aluminum

Silicates. Mineral fibers were shredded into fine fragments before adding to the mixture.


Georgia's Permeable European Mixture Gradations for
Limestone and Granite Mixes


100
V 90
*o 80-
70
S60
S50
40
30
S20-
10 m
0
No No No No No No No 3/8" 1/2" 3/4
200100 50 30 16 8 4
Sieve Sizes

-- Georgia PEM Gradation U Max Control Points A Min Control Points

Figure 2-2. Georgia's Permeable European Mixture gradation band

2.4.2 Sample Preparation for Determination of Optimum Asphalt Content

Based on experience, the Georgia DOT procedure almost always results in design

asphalt content of 6 percent, when Georgia granite aggregates are used. However,

following the GDOT GDT-114 (1996) procedure, three trial mixtures were prepared at

different asphalt contents. The trial asphalt content of 5.5%, 6% and 6.5% were selected

for the Nova Scotia granite blend for choosing the asphalt content that results in a

minimum VMA. As per GDT 114 (1996), the specified range of percent asphalt content

is 5.5%-7.0%.

As a note, based on the early experience with the use of only three trial asphalt

contents to obtain an optimal asphalt content, it was observed that it is necessary to use

four trial asphalt contents for determining the optimum asphalt content. Choosing only










three asphalt contents will always result in one of the chosen asphalt contents to show a

minimum, whereas choosing four asphalt contents will result in a true minimum that can

be verified. Figure 2-3 shows example of determination of higher asphalt content as

optimum asphalt content due selection of (3) trial asphalt contents.


Voids in Mineral Aggregates(VMA) Vs Asphalt
Content (%AC)

29.60

29.40 Higher optimum
_29.20 asphalt content with
(3) trail asphalt
29.00

28.80

28.60

28.40

28.20
5.0 5.5 6.0 6.5 7.0 7.5
% AC

Figure 2-3. Example of determination of inconsistent optimum asphalt content

Because of this reason, a broader range of trial asphalt contents was used for the

limestone mixture, namely 5.5%, 6.0%, 6.5% and 7%. For each trail asphalt content

three pills were prepared.

2.4.4 Mixing and Compaction of Samples for Determination of Bulk Specific Gravity

Sieved aggregates from each stockpile are batched by weight of 4400 grams for

each pile. Three pills are prepared for each trial percentage. Hydrated lime 44 grams

(1.0% of aggregate weight) is added to batched samples. Table 2-2 shows the amount of

material used for mixing. Aggregates, tools, mixing drum, shredded fibers and the asphalt

binder are heated to 3300 F 3.5 o F (1650 C 2.5 o C) for at least 3 hours. Aggregates

are mixed with asphalt at all trial asphalt contents. Just before mixing, add the required









amount of mineral fibers to the aggregate. Table 2-2 shows amount of aggregates and

asphalt used for each trial blend. Once the sample is mixed it is placed in a clean metal

tray. Due to the presence of the SBS in the asphalt binder, these mixtures tend to be

"sticky" making the mixing somewhat challenging. In particular, it is important to ensure

that there is no loss of fines while retrieving the mix from the mixing drum. The

AASHTO RM 30 specification for loss of fines was used, requiring that a maximum 0.1

percent loss of fines. After mixing, mixtures are aged for short term of two hours at 3200

F 3.5 0 F (1600C 2.5 0 C) as per AASHTO PP2 (1994).

The specimens are compacted to 50 gyrations using the Superpave Gyratory

Compactor. Molds should be lubricated. The angle of gyration during compaction is 1.25

degrees. From prior experience, compacted samples should not be retrieved from molds

immediately. They should be allowed to cool for lhr 45 min before extracting the

specimens from the molds. Once the specimen is ejected from the mold, it is allowed to

cool for another 5 minutes at ambient room temperature before handling. It was found

that if sufficient cooling of the specimen after extraction of the specimen from the mold

were not followed (especially for granite mixtures), small aggregate particles would tend

to dislodge and stick to gloves due to the high specimen air voids. Finally, it was found

that it was necessary to allow the pills to cool at ambient room temperatures for another

24 hours before processing them any further.









Table 2-6. Material quantities

Bulk Specific Gravity

Aggregate Weight = 4400 grams

AC Weight Fiber Weight
AC Content AC Weit Fer Total Weight
(Grams) (Grams)
5.5 256.1 18.6 4674.7
6 280.9 18.7 4699.6
6.5 305.9 18.8 4724.7
7 331.2 18.9 4750.1
5.5 58.2 4.2 1062.4
6.0 63.8 4.3 1068.1
6.5 69.5 4.3 1073.8
7.0 75.3 4.3 1079.6

2.4.4 Determination of Optimum Asphalt Content

The determination of bulk specific gravity test in accordance with AASHTO T166

(2000) cannot be conducted on the PFC mixtures because of their high air voids. The

determination of Saturated Surface Dry (SSD) weight of the pills is not reliable for

mixtures at these high air void contents as per Cooley et al (2002). Therefore, bulk

specific gravity (Gmb) of pills was determined by Dimensional analysis, as described in

GDOT-114 (1996). The determination of Theoretical Maximum Specific Gravity (Gmm)

was made via the use of the Rice test procedure as per AASHTO T209 (2004). For

preparation of samples for determination of Theoretical Maximum Specific Gravity as

per AASHTO T-209-99 (2004), aggregates are batched by weight of 1100 grams. Two

mixes for each trial asphalt percentage are prepared.

Once all trial asphalt content pills had been prepared, the VMA was determined

from the Theoretical Maximum Specific Gravity (Gmm) and the Bulk Specific Gravity

(Gmb) determined from Dimensional analysis. The design asphalt content is selected at

the point of minimum VMA. The main purpose of using minimum VMA criterion is to









ensure reasonably high asphalt content of the mixture. Secondly, VMA is calculated on a

volume basis and is therefore not affected significantly by the specific gravity of

aggregate.

Refer Appendix A for detail calculations and Laboratory work sheets of volumetric

properties of PFC mixtures.

Figure 2-4and Figure 2-5 show a summary of the volumetrics for the limestone and

granite mixtures. Optimum asphalt contents of PFC mixtures were found to be 6.5% and

6.0% for the limestone and granite mixtures, respectively. The porous nature of limestone

resulted in a higher optimum asphalt content.


















Effective Sp Grav.
of Agg. % AC6 Gmm' Gmb2 VMA3 (%) VTM4 (%) VFA (%

2.513 5.5 2.323 1.877 29.40 19.21 34.67

6.0 2.314 1.908 28.62 17.54 38.71

6.5 2.298 1.927 28.30 16.16 42.89

7.0 2.286 1.934 28.42 15.39 45.84


Voids in mineral aggregates


29.50

S29.00

| 28.50-

28.00
4.0 5.0 6.0
% AC


Voids filled with asphalt


4800
46 00 -
44 00 -
42 00
40 00
3800
>3600
34 00
32 00
7.0 8.0 3000-
40 50 60 70 80
% AC


Voids in total mix


20 00
1900
1800
S1700
1600
1500


40 50 60
% AC


Figure 2-4. Mix Design of OGFC with aggregate type: Limestone


Optimum Asphalt Content: 6.5% VMA at Optimum Asphalt Content:- 28.30%
Mineral Fiber: 0.4% of Total Mix Aggregate Type: Limestone
Gmm1 = Maximum specific gravity of mixture, Gmb2 = Bulk specific gravity of mixture, VMA3 = Voids in Mineral Aggregates,
VTM4 = Voids in Total Mix, VFA5= Voids filled with Asphalt, AC6 = Asphalt Content


70 80














Effective Sp Grav.
of Agg. % AC6 Gmm' Gmb2 VMA3 (%) VTM4 (%) VFA (%)
2.641 5.5 2.442 1.936 30.74 20.72 32.60
6 2.414 1.961 30.23 18.78 37.86
6.5 2.389 1.967 30.38 17.68 41.82


Voids in mineral aggregates


30.80
30.70
S30.60
S30.50
S30.40
>30.30
30.20
30.10


Voids filled with Asphalt


44.00
42.00
40.00
38.00
36.00
34.00
32.00
30.00


Voids in Total Mix


21.00
20.00
19.00
18.00
17.00


5 5.5 6
% AC


5 5.5 6
% AC


6.5 7


5 5.5 6
% AC


Figure 2-5. Mix Design of OGFC with aggregate type: Granite

Optimum Asphalt Content: 6.0% VMA at Optimum Asphalt Content:- 30.23%
Mineral Fiber: 0.4% of Total Mix Aggregate Type: Limestone
Gmm = Maximum specific gravity of mixture, Gmb2 = Bulk specific gravity of mixture, VMA3 = Voids in Mineral Aggregates,
VTM4 = Voids in Total Mix, VFA5 = Voids filled with Asphalt, AC6 = Asphalt Content


0f


6.5 7


T;rrl


6.5 7









2.5 Evaluation of Film Thickness Criterion in PFC Design

The Georgia DOT uses a required minimum calculated asphalt film thickness

criterion for ensuring that the mixture has enough asphalt for adequate durability._Since

durability of mixtures is a surface phenomenon, where the binder is damaged from the

surface inward, a mixture with a low film thickness is expected to damage more than a

mixture with a thicker film, irrespective of surface area. Therefore, it is important to

clearly establish a link between the calculated film thickness and the physics of the

mixture in question. The appropriate film thickness calculation is affected by the

aggregate structure of the mix. The first attempts to calculate minimum asphalt film

thicknesses were made by Goode and Lufsey (1965). Their method was based on

empirical considerations, leading to the development of the theoretical film thickness

(Hveem, NCAT 1991), which assumes that all aggregates are rounded spheres, with

predefined surface areas, which are coated with an even thickness of asphalt film.

Recognizing that these "theoretical film thickness" calculations were developed

primarily for fine-graded mixtures with very different aggregate structures from that

found in coarse-graded mixtures, let alone OGFC and PFC mixtures, Nukunya et al.

(2001) developed an effective film thickness concept based on a physical model of

coarse-graded mixtures. Nukunya, et al. (2001) observed that the aggregate structure for

fine- and coarse-graded mixtures is fundamentally different, as shown in Figure 2-6

Fine-graded mixtures tend to have more continuous grading such that the fine-aggregates

are an integral part of the stone matrix. Coarse mixtures, on the other hand, tend to have

aggregate structures that are dominated by the coarse aggregate portion (i.e., stone-to-

stone contact).


















COARSE FINE
Figure 2-6. Aggregate Structure for Coarse and Fine Mixtures (Nukunya et al. [2001])

Therefore, coarse-graded PFC mixtures are effectively composed of two

components: the first one is the interconnected coarse aggregate, and the second

component is the fine mixture embedded in between the coarse aggregate particles. The

mixture made up of asphalt and fine aggregates coats the coarse aggregate particles, and

the fine aggregates within that matrix have access to all the asphalt within the mixture.

This results in film thicknes that is much greater than that calculated using conventional

theoretical film thickness calculation procedures that assume that the asphalt is uniformly

distributed over all aggregate particles. To account for the different nature of the

aggregate structure in coarse-graded mixtures, a modified film thickness calculation,

entitled the "effective film thickness," was developed by Nukunya, et al. (2001), in which

the asphalt binder is distributed onto the portion of the aggregate structure that is within

the mastic.

Also recognizing that the Theoretical Film Thickness (Hveem, NCAT 1991) may

not adequately represent the physics of PFC mixtures, the Georgia DOT introduced a

modified film thickness calculation. However, the Georgia DOT modified film thickness

calculation method is based on empirical considerations and yields similar results to the

theoretical film thickness calculations.









More recently, work at the University of Florida under the direction of Drs. Roque

and Birgisson has led to the establishment of a tentative gradation selection framework

for the optimization of the fracture and rutting resistance of dense graded mixtures. Key

concepts in this new proposed framework include the observation that enhanced cracking

and rutting resistance can be obtained by ensuring that the aggregates in the course

portion of the mixture gradation interact sufficiently amongst each other to allow for the

effective transfer of forces through the course-aggregate portion of the mixture. This

interaction of the course aggregate component should not reach down to the finer

materials, so as to control mixture sensitivity. For optimizing the fracture resistance of

mixtures, the material within the interstitial volume of the course aggregate portion also

needs to be proportioned and designed so that an adequate Dissipated Creep Strain

Energy (DCSE) limit is maintained, as well as providing enough flow and ductility to

enhance the fracture resistance of the mixture. Too little interstitial material, or

interstitial material with a low creep strain rate, will result in a brittle mixture. It is

anticipated that these gradation concepts will be transferable to OGFC and PFC mixtures,

thus allowing for the development of guidelines for the selection of gradations that

optimize the resistance to cracking and rutting. Using these concepts it is also possible to

define a modified film thickness that is calculated strictly based on the interstitial volume

component of the mixture.

In the following the Georgia DOT modified film thickness criterion will be

compared to the effective film thickness criterion developed by Nukunya, et al. (9), as

well as the new film thickness criterion based on interstitial volume considerations. For

completeness the "Theoretical Film Thickness proposed by (Hveem, NCAT 1991) is









also calculated and included in the comparison, even though it is recognized that it may

not adequately represent the structure of PFC mixtures. However, first the methods for

calculating these asphalt film thicknesses are reviewed.

2.5.1 Review of Asphalt Film Thickness Calculation Methods

Goode and Lufsey's method

Even though this method is not used in this research, it is important to note the

contributions of Goode and Lufsey (1965), who related empirically asphalt hardening to

voids, permeability and film thickness. They recognized that the hardening of the asphalt

binder in a mix was a function of air voids, film thickness, temperature, and time.

Goode and Lufsey (1965) introduced the concept of the ratio of the air voids to

bitumen index, as a measure of the aging susceptibility of a mix (developed for dense

graded mixture with 4% air voids). Goode and Lufsey (1965) had proposed a maximum

value of 4.0 for this ratio, which they believed, would prevent pavement distress by

reducing the aging of the asphalt film coating the aggregate. Mathematically, what they

stated was:

AirVoids(%) 4
BitumenIndex x 103 (Maximum) (2.1)

Where:

Film thickness (microns) = Bitumen index x 4870

Equation 2-1 with the air voids content of the mixture is reduced to a minimum

film thickness requirement based on air voids to bitumen index ratio analysis. The film

thickness then varies with the percent air voids as follows (Goode and Lufsey, 1965):










AirVoids(%)/x 4870
Film sickness = Voids() x 4870 (Minimum) (2.2)
4 x 10

The total air voids in the compacted PFC limestone mixtures at 50 gyrations is

16.16%. Goode and Lufsey's minimum film thickness requirement for 16.16% is 19.67

microns.

Theoretical film thickness method

This technique for calculating film thickness is based on the surface area calculated

as per Hveem (1991). The surface area factors suggested by Hveem (1991) is shown in

Table 2-7. The Film thickness of asphalt aggregates is a function of the diameter of

particles and the effective asphalt content. The film thickness is directly proportional to

volume of the effective asphalt content and inversely proportional to diameter of particle:

V x1000
T em (2.3)
iS SA x W


Tfm = Film Thickness

SA = Surface Area

Wgg = Weight of aggregate

Table 2-7. Surface Area Factor Hveem (1991)
Sieve Size Surface Area Factor

Percentage Passing Maximum Sieve Size 2
Percent Passing No. 4 2
Percent Passing No. 8 4
Percent Passing No. 16 8
Percent Passing No. 30 14
Percent Passing No. 50 30
Percent Passing No. 100 60
Percent Passing No. 200 160









Effective film thickness method (Nukunya et al, 2001)

According to this method only aggregates passing the No. 8 Sieve are taken into

account in the calculation of the surface area by using factors suggested by Hveem (1991)

Then Equation 2-3 is used for calculating Film Thickness.

Table 2-8. Surface area Factor suggested by Nukunya (2001) for coarse aggregate
structure
Surface Area
Sieve Size Factor
Factor
Percent Passing No. 8 4
Percent Passing No. 16 8
Percent Passing No. 30 14
Percent Passing No. 50 30
Percent Passing No. 100 60
Percent Passing No. 200 160

Modified film thickness method used by gdot

Georgia developed this method primarily for PEM mix with granite aggregate. The

basic assumption was that the absorption of asphalt is very low or no absorption by

surface pores of granite aggregate. The method is empirical and assumes that fixed

aggregate unit weight per pound of aggregate, based on Georgia aggregates. Hence, the

T
effective film thickness ( eff) is given as:

[ 453.6 g per Pounds divided by % Aggregate] [ 453.6 g per Pounds (2.4)
f Surface area in square ft / lb 0.09290Sq. m per sq. ft. Sp. gr. of AC
Where,
T, = Effective Film Thickness

Film thickness based on interstitial volume concept

The aggregate interaction curve is plotted to determine the portion of the gradation

curve with interacting aggregate sizes. Following is equation used for calculating points

of interaction










%Retained Particle Interaction Point = (%Retainedat Sieve Size) *100 (2.5)
-(%Retained at Succesive Sieve Size + (%Retained at Sieve Size)

The aggregates are considered to be interacting, if the percent-retained particle

interaction is between 30% and 70%. Any point that falls outside these limits is

considered to be non-interacting. Therefore, aggregate sizes below this break point are

not interacting towards contribution of strength. These aggregate sizes are filling the

cavities between the coarse aggregate structure defined by aggregate sizes above the

break point. The aggregate sizes below the break point along with asphalt are

contributing to Interstitial Volume. Mastic, comprising aggregate sizes below the break

point, asphalt, and air voids, form the interstitial volume of the compacted mixture.

Hence, the interstitial volume is the ratio of mastic in specimen to the total volume of the

compacted mixture, as shown in Equation 2-6:

(Volume of Mastic)
Interstitial Volume = ( f Mastic) (2.6)
Total Volume of Compacted Mixture

In order to calculate the film thickness of the particles in the interstitial volume, the

surface area of the particles in the interstitial volume needs to be determined. As per the

hypothesis discussed above, aggregates below the break point are within the interstitial

volume. Hence, the surface area (SA) of aggregates below break point can be obtained

from the surface area factors given in Table 2-9. As the absorption in granite is


negligible, the as the effective asphalt content (Veff) is taken to be the total asphalt


content of the compacted mixture. Weight of aggregates (Wagg) in air is taken into

account for calculating film thickness. Equation 2-7 denotes calculation of film thickness

with in interstitial volume:









V x 1000
T elm (2.7)
fim SA x W
Recognizing that these film thickness calculations all use effective asphalt content

to determine the available amount of asphalt binder for the coating of particles, it is

important to establish clear guidelines for determining the effective asphalt content of

PFC mixtures.

Table 2-9. Surface area factors for Interstitial Volume
Surface
Sieve Size Area
Factor
Percentage Passing Maximum Sieve Size 2
Percent Passin No. 4 2


Aggregate Aggregate
with in with in
interstitial interstitial
volume volume


The Georgia DOT method of film thickness calculations assumes that there is no

absorption of asphalt into the aggregate surfaces. Their method of film thickness

calculation is an empirical approach. This assumption may be a reasonable approximation

for low absorption granite aggregates. However, for high absorption limestone

aggregates it is necessary to account for absorption. In this research, asphalt absorption

was estimated using two approaches:

1) Asphalt absorption obtained from basic volumetric equations is used to calculate

effective asphalt content. This is the true asphalt contributing towards in film thickness: -

13. Effective Specific gravity (Gsb): The effective specific gravity is calculated from
the maximum specific gravity (Gmm) of mixture and Asphalt content (Pb).









Pb
1-^
G 100 (2.8)
Pb
1 100
Gmm Gb

14. Asphalt Absorption (Pa,,): The absorbed asphalt content is differences of bulk
volume of aggregate and the effective volume.

(Gse Gsb>
asb = 10Ox s x Gb (2.9)
\ Gse x Gsb

15. Effective Volume of Asphalt (Veff): The effective volume of asphalt is amount of
asphalt available for coating aggregates, which is obtained by subtracting absorbed
asphalt from Total Asphalt Content (Pota1).

V = Potal Pas (2.9)



2) Determination of effective asphalt content based on bulk specific gravity

determined through from the CoreLok test procedure as per CoreLok manual (2003).

The main justification for using the CoreLok procedure is that open graded mixes readily

absorb water and drain quickly when removed from the water tank, during the

determination of Saturated Surface Dry (SSD). Weight conditions in traditional

laboratory-based procedures for determining. The lack of control over the penetration and

drainage of water in and out of asphalt specimens creates a problem with the water

displacement measurement using the current principles for determination of specific

gravity as per Cooley et all (2002). The CoreLok system makes the determination of

SSD conditions unnecessary.

Perform calculation as per directions given in Data Collection Table: 2.10









Table 2-10. CoreLok calculation Sheet
A B C D E F G H I
Dry
Sam- Dry Sealed Sample
ple Bag Sample SampleWeight Bag
ID Weight Weight Weight After Volume Total Volume Volume Bulk
(g) before in Water Correction Volume of of Specific
Sealing Water Submersion RatioFrom (A + D) Sample Sample Gravity
(g) (g) (g) B/A Table C A/F (G-H) B/I
I
II______ __________

After determination of Bulk Specific gravity (Gmb) following steps in calculation

are involved for estimating the effective asphalt content. Air Voids in compacted mix

(VTM ) and Voids in Mineral Aggregates (VMA) are calculated using Equation 2-10 and

Equation 2-12 based on bulk specific gravity determine by CoreLok method.




VTM -- Gmb x100 (2.10)
Gmm0

W

VMAA =100 x100 (2.11)

Gmb 1

VTM.V
Veff = -V Vagg + V, (2.12)
100

Where,

VT = Total volume of compacted specimen

Vagg = Volume of aggregate

Gmm = Maximum theoretical specific gravity.

Gsb = Aggregate bulk specific gravity









VTM = Voids in total mix

VMA = Voids in Mineral aggregate.

W,= Weight of Total specimen

Wg = Weight of aggregate

2.5.2 Comparison of Results Obtained from Each Film Thickness Calculation Method

Limestone has higher absorption capacity than granite aggregate. Figure 2-7 shows

the absorption of asphalt into the surface cavities of limestone aggregate, therefore

reducing the effective asphalt content and resulting in a lower film thickness when

compared to granite mixtures.














(a) (b)
Figure 2-7. (a) Granite with high film (Required against stripping) (b) Limestone with
low film thickness as compared with granite due to absorption

The four different asphalt film thickness calculations methods discussed previously

were used to calculate the film thickness of asphalt with in compacted granite and

limestone PFC mixtures.

The surface area calculated by the Nukunya et al (2001) Method and the Interstitial

Volume method is exactly same for the two mixtures evaluated, due to the fact that the

break point defining the interstitial volume is at the No. 8 Sieve Size.









Table 2-11. Com prisonn of Film Thickness method for Limestone mixture
Film Thickness (microns) Film Thickness (microns)
Method
Asphalt absorption Corelok Method
Theoretical Film
Thickness 34.20
(Hveem 1991) 31.22
Nukunya's
Effective Film 50.71
thickness 46.29
GDOT 34.80 31.58
Interstitial
50.71
Volume 46.29

Table 2-11 shows the comparison of true film thickness to film thickness calculated from

CoreLok bulk specific gravity.

CoreLok is determining comparative film thickness. Nukunya's method and Interstitial

volume method are predicting higher film due consideration of coarse aggregate

structure.

Table 2-12. Comparison of Film Thickness method for Granite mixture
Film Thickness (microns)
Method
Asphalt Absorption

Theoretical Film
Thickness (Hveem 37.25
1991)

Nukunya's Effective 55
55.23
Film thickness
GDOT 38.10
Interstitial Volume 55.23

As shown in Table 2-12, Comparison of Film Thickness method for Granite

mixture, GDOT method is over predicting film thickness. Hence, in summary, either the

CoreLok or the equivalent water absorption methods can be used. However, the Corelok

method is still under review and development, nationally. Therefore, until the method

has been thoroughly verified on the national level, it is recommended that the equivalent









water absorption method be used as a lower limit on asphalt absorption. Similarly, the

asphalt film thickness of the aggregates within the interstitial volume is the most

theoretically correct method.

However, it is still under development and evaluation. Therefore, it is

recommended that the Effective Film Thickness calculation proposed by Nukunya, et al.

(2001) be used to determine the film thickness of PFC mixtures.

2.5.3 Relative Minimum Film Thickness Requirement

For establishing minimum film thickness requirement based on Effective Film

Thickness Nukunya et all (9), Georgia Department of Transportation minimum film

thickness criterion is used as standard. According to GDOT minimum film thickness

required for granite PFC mixture against stripping is 27 microns for surface area

calculated based on GDOT factors. This requirement is not specified in their specification

but they use it as tentative film thickness criterion.

Georgia DOT typically uses granite aggregate for their GPEM mixtures. Georgia

DOT, ignore asphalt absorption while calculating film thickness as per Eason (2004). But

limestone due to its porous surface texture has high asphalt absorption capacity. This

property of limestone does not allow attainment of high film thickness. Aggregates with

different asphalt absorption will lead different minimum film thickness. Therefore, the

relative minimum film thickness requirement is calculated for set of range of asphalt

absorption, i.e. 0-0.5%, 0.5-1 %, 1 % or more. While calculating minimum film thickness

requirement for each of these ranges, upper limit of range is considered.

For calculating the relative minimum film thickness requirement, 27 micron is used

to back calculate the effective asphalt content (VeffDOT ).









As Georgia DOT ignores asphalt absorption this effective asphalt content is total

asphalt content of the mixture. Subtracting upper limit of range of asphalt absorption

(Asphalto,,,,, ) from this the total asphalt content gives actual effective asphalt content

(VeffNukuya ). This value of effective asphalt content is substituted in standard film

thickness Equation 2-3 using surface area as per Nukunya et al (2001) as shown in Step V

for calculating relative minimum film thickness (TRelave Mim.nmum)

Optimum gradation band for surface area calculation

A gradation band, which is representative of all gradations with in specified control

limits, is required for calculating surface area for relative minimum film thickness

requirement. Average of maximum control points and minimum control points of

specified gradation limits as per GDT-114 (1996) to obtain optimum gradation, which

represents gradation between those gradation limits.

Figure 2-8 shows optimum gradation band used for calculating surface area. Job

mix formula of this optimum gradation showed in Table 2-13 is used to calculate surface

area as per Georgia DOT method (SurfaceArea GDO) and Nukunya et al. (2001)

(SurfaceAl ea _:,,,)). It is assumed that this optimum gradation represents the

different gradation band with in this specified limit. Therefore the film thickness

calculated for this optimum gradation band represents al set of gradation band with in this

gradation limit.











Optimum Gradation Band for Minimum Film thickness requirement Calculation


- Max Control points Min Control Points
-- Optimum Representative Gradation
Figure 2-8. Optimum Gradation Band for Calculating Minimum film thickness
requirement


Table 2-13. JMF of Optimum gradation for Gradation limits as per GDT 114 (1996)
Type Optimum
% Amount Gradation
Sieve SizeSize^0.45Band
37.5 5.11 100
25 4.26 100
19 3.76 100
12.5 3.12 90
9.5 2.75 48
4.75 2.02 18
2.36 1.47 8
1.18 1.08 5
0.6 0.79 4
0.3 0.58 3
0.15 0.43 2
0.075 0.31 2

Following steps are used for calculating relative film thickness requirement: -

Step I: TmlimumGDOT = 27microns


S. .. -TmmnimumGDOT x SurfaceAreaGDOT aggregate


1000


0 -
0.00


0.50 1.00 1.50 2.00 2.50 3.00 3.50
Sieve Size^0.45


p etS II: VeffGDOT









Step III: Totalphalt = effGDOT

Step IV: VeffNukua = Totalsphlt Asphaltborpon


VeffNu, a x 1000
Step V: Telahve Minimum
SurfaceAreaNukunya(2001) Waggregate


Based on above steps minimum film thickness requirement is calculated for

different set of asphalt absorption. The relative minimum film thickness for Nukunya et

al (2001) based on this concept is tabulated in Table 2-14.

Table 2-14. Minimum film thickness requirements for different set of Asphalt absorption
Ma m Effective Minimum
Maximum
A t a tion R e Total asphalt asphalt film thickness
Asphalt absorption Range asphalt
content (ml) absorption (%) content requirement
absorption (%)
(ml) (microns)
0 % to 0.5% 213.84 0.5% 191.84 32
0.5% +to 1 % 213.84 1% 169.84 28
1%+ to 1.5% 213.84 1.50% 147.84 24
Greater than 1.5
1.5% or more 214.84 125.84 13


2.6 Recommended Specification for PFC Mixture Design

SCOPE

The method of design for a modified open graded bituminous mixture consists of

four steps. The first step is the selection of a trial aggregate blend and asphalt binder.

The second step involves the determination of optimum asphalt content and checking for

adequate asphalt film thickness to ensure durability. The third step involves the

performance of AASHTO T 305-97 (2001) (i.e. a asphalt drain down test), and the fourth

step involves the performance of AASTHO T-283 (2001). The details of each step are

discussed below.









APPARATUS

The apparatus required shall consist of the following:

1. Drain-Down equipment as specified in AASHTO T 305-97 (2001).
2. Superpave gyratory compactor.
3. Equipment to perform AASHTO T-84 and T-85.
4. Balance, 5000 gr. Capacity, 0.1 gr. Accuracy.
5. 10 metal pie pans
6. Oven capable of maintaining 330 F 3.5 F (1650 C 2.5 o C)
7. Oven capable of maintaining 350 F 3.5 F (1760 C 2.5 o C
8. Timer.

STEP 1: Determination of Trial Blend and Asphalt Binder

The aggregate trial blend should be selected to fit within the gradation limits listed

in Table 2-15 and shown in Figure 2-9. The asphalt binder should be SBS modified PG

76-22 asphalt. Either the addition of 0.5% liquid anti-strip agent or 1 percent hydrated

lime is required. The use of hydrated lime requires pretreatment of the aggregates with

the hydrated lime. 0.4 % mineral fiber by weight of total mix should be added to avoid

binder drain down.

Table 2-15. Proposed Gradation and Design specifications for Florida Permeable


Mixture
Control 12.5 mm
Tolerance Asphalt Concrete PFC
Gradation Requirement
+ 0.0 3/4 in (19 mm) sieve 100
6.1 1/2 in (12.5 mm) sieve 80-100
5.6 3/8 in (9.5 mm) sieve 35-60
5.7 No. 4 (4.75 mm) sieve 10-25
+4.6 No.8 (2.36 mm) sieve 5 10
+2.0 No. 200 (75 tm) sieve 1-4
Design Requirements
+0.4 Range for % AC 5.5-7.0
AASHTO T-283 (TSR) 80
Drain-down, AASHTO T 305 (%) <0.3










Gradation Band by Vardhan (2004)



100 A-
S90
S 80 -
70
60 -
5 50
4 40
g 30 -
S20
S 10
No No N No No No No 3/8" 1/2" 3/4"
200100 50 30 16 8 4
Sieve Sizes

Max Control Points A Min Control Points

Figure 2-9. Proposed Gradation limits for Florida Permeable Friction Course Mixtures

STEP 2: Determination of Optimum Asphalt Content and Asphalt Film Thickness

* Heat the coarse aggregate, the mould to 350 F 3.5F (176C 2.5 o C) and the
AC to 330 F 3.5 F (1650 C 2.5 o C)

* Mix aggregate with asphalt to obtain at least four trial asphalt contents, viz., 5.5%,
6%, 6.5% and 7%. Just before mixing, add the required amount of mineral fibers to
the aggregate. Prepare three samples at each of the asphalt contents

* After mixing, return the mix to oven for two hours for STOA at 3200 F 3.5 o F
(160 C 2.5 o C). Then compact to 50 gyrations using the Superpave Gyratory
Compactor

* When compacted, cool down at room temperature for 1 hour 45 minutes before
removing the specimens from the compaction mold.

* Determine Bulk Specific Gravity: Determine the density of a regular shaped
specimen of compacted mix from its dry mass (in grams) and its volume in cubic
centimeters obtained from its dimensions for height and radius. Convert the density
to the bulk specific gravity by dividing by 0.99707 g/cc, the density of water at 25
oC

Bulk Sp.Gr = W / (7 r2h/ 0.99707)

= Weight (gms) x 0.0048417/Height (in)
W = Weight of specimen in grams


R = radius in cm









H = height in cm

* Determine Theoretical Maximum Specific Gravity according to AASHTO T-209-
99 (2004).

* Calculate percent air voids, VMA and voids filled with asphalt based on aggregate
specific gravity

* Plot VMA curve versus AC content and determine point of minimum VMA, select
corresponding AC as Optimum asphalt content.

* Prepare a mixture at the optimal asphalt content.

* Determination of film thickness: -

Step (I) Determination of Effective Specific gravity (Psb): -

Pb
1-^
G, 100 (2.13)
Pb
1 100
Gmm Gb
Step (II) Determination of Asphalt absorption (Pu~): -

(Gse Gsb>
Pab = 10Ox s x Gb (2.14)
\ Gse x Gsb)
Waterabs Determined is in percentage of weight of aggregate. Convert into volume of

water in ml, by using following equation:-

P-ba Weight of _ggregite(grams) (2.15)
absabs ml 100*1.03
100 1.03

Step (III) Determination of Effective Volume of Asphalt (Vef): -


eff = PTotal Pabsabs ml (2.16)

(Where Po,,, = Total asphalt content in ml)

* Calculate the Effective Film thickness using following procedure as per Nukunya et
al (2001):

a) Determine Surface area (SA) from Table 2 below:









Table 2-16. Surface area factor as per Nukunya et al (2001)
Surface Area
Sieve Size Factor
Factor
Percent Passing No. 8 4
Percent Passing No. 16 8
Percent Passing No. 30 14
Percent Passing No. 50 30
Percent Passing No. 100 60
Percent Passing No. 200 160


b) Film thickness of asphalt (in microns):

V x 1000
"flm SAx W

where,


(2.17)


Wgg = Weight of aggregate
SA = Surface area

The minimum acceptable effective film thickness is determined as a function of the

measured percent asphalt absorption per weight of aggregate as follows:

Table 2-17. Minimum Effective Film Thickness Requirements


Percent Asphalt Minimum Required
Absorption Film Thickness
(micron)
0.5 % or less 32
0.5+ to 1% 28
1.0+to 1.5 % 24
Greater than 1.5 % 13

E Step 3: Performance of Drain-Down Test

Perform the drain test in accordance with the AASHTO T 305-97 (2001). A mix

with an optimum AC content as calculated above is placed in a wired basket having 6.4

mm (1/4 inch) mesh openings and heated 14 C (25 F) above the normal production

temperature (typically around 350F) for one hour. The amount of cement, which drains









from the basket, is measured. If the sample fails to meet the requirements of maximum

drain down of 0.3 %, increase the fiber content by 0.1 % and repeat the test.

Step 4: Performance of Moisture Damage Test

Perform the moisture damage test in accordance with AASHTO T-283 (2003) on

compacted specimen. The specimens are rolled in 1/8" wire mesh which are kept in

position using two clamps on either edge of the pill for avoiding mixture damage or

breakdown at the conditioning temperature of 60C (140'F). Minimum requirements

should include TSR of 0.8 or greater.

2.7 Conclusion of Verification of PFC mixture Design Procedure

The research presented in this chapter led to the following conclusions:

* It is recommended that at least (4) trial asphalt content should be used for
predicting fairly accurate optimum asphalt content.

* Only PG 76-22 SBS modified binder containing 0.5% liquid anti stripping agent
should be used.

* Minimum amount of batched sample for sample should not be less than 1000 grams
for all purposes of testing.

* Air voids levels in the PFC limestone mixture were around 16% at 50 gyrations.
Gradation analysis by Varadhan (2004) on extracted aggregate after compaction
showed that the limestone undergoes crushing early in the compaction process.
Therefore, the specified gradation limits may have to be adjusted for limestone to
obtain air voids in the desired 18-22 percent range.

* In order to ensure adequate durability, the effective film thickness method
developed by Nukunya, et al. (2004) should be used. In order to determine the
effective asphalt content, the aggregate asphalt absorption should be used.














CHAPTER 3
EVALUATION OF 1-295 PFC MIX DESIGN

PFC pavements are subjected to high temperature variance, hydroplaning and are in

direct contact with rolling loads. In order to check field performance of PFC in Florida,

construction of a test section was proposed at 1-295, Jacksonville, FL. The Mix design of

for this section follows the procedure discussed in Chapter 2.

3.1 Objective

The objective of this study is to evaluate mix design procedure of PFC mixture at I-

295 test section. The 1-295 test section will be monitored for its long-term performance.

Gradation selections for optimizing fracture resistance. Determination of optimum

asphalt content for attaining minimum voids in the mineral aggregate (VMA) for

ensuring high binder coating without drain down. Obtain a mixture for 1-295 with highest

Energy Ratio among selected gradation to ensure best performance.

3.2 Scope of Project

Separate mix design was carried on gradation proposed by DOT contractor

(Gradation (1)) and designed gradation (Gradation (2) to determine optimum asphalt

content. Following is the complete plan of project:-

For each of the gradations, 4-trial asphalt percentages are used to obtain a VMA

curve. The reason for selecting 4-trial percentages is to obtain polynomial curve for

determining point of minimum VMA. Sieving, watching, mixing and compaction, as

discussed in section 3.3.1 of this chapter, of mixes is done as specified in previous

development in laboratory. Asphalt used is SBS modified PG76-22, which contains 0.5%









anti strip agent in addition to 1% of hydrated lime added to aggregates to resist against

stripping. Dosage rate of mineral fiber is 0.4% by total weight of mix. Superpave

Indirect tensile test is run on compacted mixes for both gradations, in order to obtain

fracture test parameters including energy ratio. Process of testing and criteria considered

are discussed in section 3.4 of this chapter. Selection of gradation based on higher energy

ratio for 1-295 test section. Effect of moisture conditioning and long-term oven aging on

selected gradation.

3.3 Materials used for 1-295 PFC project

3.3.1 Aggregate and Hydrated Lime

The final aggregate blend for Gradation (1) and Gradation (2) is composed of #67

Granite stone from Pit No TM-579/NS-315, #78 Granite Stone from Pit No GA-383 and

Granite Screens from Pit No. TM-579/NS-315. The FDOT codes for these source stone

stockpiles, #67 Granite is '54', #78 Granite is '54', and for Granite Screens is '23'

respectively. The producer of these aggregates is 'Martin Marietta Aggregate'. Figure 3-1

shows the gradation band used for 1-295 PFC project and control points as per FDOT

specification SECTION 337. Table 3-1 and Table 3-2 gives details of composing of job

mix formula of Gradation (1) and Gradation (2) respectively. One percent by weight of

aggregate hydrated lime is added to the mixture as an antistrip agent. 'Global Stone

Corporation' provided hydrated lime.

3.3.2 Binder and Mineral Fiber

An SBS polymer modified asphalt cement PG 76-22 with 0.5% antistrip agent was

used in this project. Mineral fiber used was regular FIBERAND ROAD FIBERS.

'Atlantic Coast Asphalt Co.' supplied asphalt and mineral fiber. The dosage rate of

mineral fiber was 0.4% by weight of total mix.










1-295 PFC Gradations


100.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0


No No No No
200100 50 30


No No
8 4

Sieve Sizes


-- Gradation (1) DOT
A Min Control Points


3/8" 1/2" 3/4"


* Max Control Points
--- Gradation (2) UF


Figure 3-1. Gradation of 1-295 PFC mixtures


Table 3-1. JMF composition of Gradation (1)
#78 Granite
Type #67 Granite Granite Screens Lime JMF Control Points
% Amount 20 70 9 1 100 Max Min
Sieve SizeSizeA0.45
37.5 5.11 100 100 100 100 100
25 4.26 100 100 100 100 100
19 3.76 100 100 100 100 100 oo00 100
12.5 3.12 60 95 100 100 89 95 85
9.5 2.75 45 62 100 100 62 65 55
4.75 2.02 8 6 91 100 15 25 15
2.36 1.47 4 4 61 100 10 10 5
1.18 1.08 3 3 38 100 7
0.6 0.79 2 3 22 100 5
0.3 0.58 2 3 15 100 5
0.15 0.43 2 2 7 100 3
0.075 0.31 1 1 3.5 100 2 4 1

Table 3-2. JMF composition of Gradation (2)
#78 Granite
Type #67 Granite Granite Screens Lime JMF Control Points
% Amount 30.0 60.3 8.8 1 100 Max Min
Sieve SizeSizeA0.45
37.5 5.11 100 100 100 100 100
25 4.26 100 100 100 100 100


U"










Table 3-2. Continued
#78 Granite
Type #67 Granite Granite Screens Lime JMF Control Points
% Amount 30.0 60.3 8.8 1 100 Max in
19 3.76 100 100 100 100 100 1001oo
12.5 3.12 60 95 100 100 85 95 85
9.5 2.75 45 62 100 100 61 65 55
4.75 2.02 8 6 91 100 15 25 15
2.36 1.47 4 4 61 100 10 105
1.18 1.08 3 3 38 100 7
0.6 0.79 2 3 22 100 5
0.3 0.58 2 3 15 100 5
0.15 0.43 2 2 7 100 3
0.075 0.31 1 1 3.5 100 24 1



3.4 Location of Project

Figure 3-2 shows the project location, which is on 1-295 between Lem Turner Road

and Duval Road in Jacksonville, Florida. The test section starts at MP 31.910 (Station

1684+88.86 on 1-295) and ends at MP 32.839 (Station 1733+91.61 on 1-295), outside

lane at northbound and south bound.


w

VIJa, S i .e ,1-,l, .i' rf.'
FI. Ie
;I~~iljl '-"!1 Ei'~

F-

Pt,~e' Lmcd~m


AJU'jA


Figure 3-2. Project Location


%a AV .,1.
ruh ir C drI e1 r, rp fq









3.5 Specification and Hypothesis Used

As per FDOT specification SECTION 337-4, developed based on previous work

done described in Chapter 2, and the design of the PFC mixtures is based on the final

procedure developed in Chapter 3. The basic steps in the mixture design may be

summarized as follows:

1. The design number of gyration should be 50.

2. Final JMF should be within the gradation limit specified in Table 337-2 of FDOT
specification SECTION 337-3.3.2. This specified gradation limit is shown in Table
3-3

3. The PFC mix design should use a SBS modified PG 76-22 asphalt binder.

4. The optimum asphalt content should be selected at the minimum voids in the
mineral aggregate (VMA) content.

5. The air void content should be between 18 and 22 percent.

6. Hydrated Lime dosage rate of 1.0% by weight of the total dry aggregate.

7. Mineral fiber dosage rate of 0.4% by weight of the total mix.

Table 3-3. PFC Gradation Design Range from FDOT specification SECTION 337
Control Points
Sive Size
Max Min
(mm)
% Amount Passing
37.5
25
19 100 100
12.5 95 85
9.5 65 55
4.75 25 15
2.36 10 5
1.18
0.6
0.3
0.15
0.0754 1









The FDOT contractor proposed a JMF (Gradation (1)) for the given source

gradations of stockpiles. As the source gradation was gap graded and gradation limits

according to SECTION 337 are tight, it was difficult to adjust this gradation to obtain

another candidate gradation. Therefore, only one other trial gradation was used in

addition to the contractor's gradation. The second gradation, denoted as Gradation (2)

was based on increasing the amount of coarser stone in the mix. This objective was

accomplished by increasing the percentage of # 67 granite from 20 % to 30 %.

Even though, the material type used in Georgia PEM mix design development is

different than in the 1-295 PFC project, its characteristics are used as base for the

evaluation of fracture results. Table 3-1 and Table 3-2 shows source gradation and final

JMF of Gradation (1), Gradation (2) and Georgia PEM gradation. The hump in gradation

at No. 4 sieve might create some effect fracture resistance because of uneven aggregate

arrangement in mix.

3.6 Determination of Optimum Asphalt Content

Based on number of experiments, the Georgia DOT suggested that if the gradation

is within the specific limits, the initial estimate comes out to be 6% using granites that are

native to Georgia. Hence, the probable optimum asphalt content with in this gradation

band is 6% if the aggregate is Georgia granite. Depending on surface texture and

angularity of aggregates, or a change in the JMF might cause changes in optimum asphalt

content. Therefore, four trial percentages (5.5%, 5.8%, 6.2% and 6.5%) for each

gradation, and two piles for each trial percentage are produced in this project.









3.6.1 Mixing and Compaction

Sieved and batched aggregates, asphalt and mineral fiber are preheated for 3 hours

in an oven before mixing. Due to the SBS modified viscous asphalt and addition of

mineral fiber; the mixing temperature was selected as 330 o F (1650 C), to maintain

enough flow during mixing. All tools and mixing drum were also preheated to 3500 F

(1760 C).

While mixing, asphalt is added to mix of aggregate and mineral fiber. These SBS

mixes are very sticky, making mixing and handling challenging. Therefore, it is

important to ensure that while retrieving material from mixing drum there is no loss of

fines. Mixing procedure was the same for both Rice testing specimens as well as the

Superpave gyratory compacted specimens. It is also important to avoid over heating of

binder during mixing, as it causes aging of binder.

Before compaction, the mixes are subjected to Short Term Oven Aging (STOA) for

two hours, which includes stirring after one hour. Compaction temperature is reduced to

320 o F, for avoiding draindown of binder during compaction. As already stated, 50

gyrations were used to attain compaction level similar to field after traffic consolidation.

The angle of gyration kept during compaction was 1.25. Essentially, because of sticky

nature of these mixture oil is sprayed in molds.

From prior experience, compacted samples are not retrieved from the molds

immediately. They are allowed to cool from lhr 45 min before retrieving from molds.

Once the specimen is ejected from the mold let it cool for 5 min before holding specimen.

Especially in granite mixtures if cooling after ejection is not allowed small aggregates

due to high air voids stick to gloves and comes out causing discontinuity in specimen.









Allow piles to cool for 24 hr before any further processing or activity related to the

compacted specimens.

Determination of Rice specific gravity (Gmm) on loose PFC mixes was done in

accordance with AASHTO T209 (See Appendix B). Calculations of all volumetric

properties are shown in Appendix B. The determination of optimum asphalt content was

as per recommended specification, as specified in Chapter 3, by selecting AC at the

lowest point of the VMA curve.

Gradation (2) is coarser than Gradation (1), which results in more surface area in

Gradation (1) as compared to Gradation (2). Refer to Figure 3-3 and Figure 3-4 for mix

design details for Gradation (1) and Gradation (2), respectively. A decrease in effective

specific gravity of Mixture 2 with respect to Mixture 1 shows the increase in volume of

water permeable pores not absorbing asphalt. These facts support reduction in optimum

asphalt content of Gradation (2). Essentially, the VMA at optimum asphalt content is not

changing significantly for both gradations. Basically, Gradation (2) is giving air voids

(21.93 %) similar to Gradation (1) (21.2%) and all other volumetric properties are

comparable and within the restricted specification ranges. Therefore, the final selection

of gradation depends on fracture test results.




















Effective Sp Grav

of Agg % AC6 Gmm' Gmb2 VMA3 (%) VTM4 (%) VFA (%

2.732 5.5 2.513 1.944 32.777 22.655 30.883

5.8 2.501 1.955 32.603 21.820 33.073

6.2 2.473 1.964 32.600 20.578 36.877

6.5 2.470 1.966 32.721 20.379 37.718


Voids in Total Mix


Voids in Mineral Aggregates


Voids filled with Asphalt


2200


2100


2000


54 56 58


6 62 64 66
% AC


3275

3270

S3265- ---

3260______


56 58


6 62 64 66
%AC


ry uu --- ---- --- ---- --- ---
38 00
3700 _
36 00 -
35 00 --
34 00 -
33 00
3200
31 00 ---
30 00 --- ---


54 56 58


6 62 64 66
% AC


Figure 3-3. Mix Design of PFC Gradation (1) with aggregate type: Granite


Optimum Asphalt Content: 6.0% Gmm at Optimum Asphalt Content:- 2.485


Mineral Fiber: 0.4% of Total Mix VMA at Optimum Asphalt Content: 32.69%



Gmm1 = Maximum specific gravity of mixture, Gmb2 = Bulk specific gravity of mixture, VMA3 = Voids in Mineral Aggregates,


VTM4 = Voids in Total Mix, VFA5 = Voids filled with Asphalt, AC6 = Asphalt Content
















Effective Sp Grav.
of Agg. % AC6 Gmm' Gmb2 VMA3 (%) VTM 4 % VFAs (%

2.722 5.5 2.497 1.935 32.819 22.501 31.440
5.8 2.494 1.946 32.648 21.963 32.727

6.2 2.479 1.953 32.713 21.245 35.057
6.5 2.452 1.957 32.788 20.212 38.357


Voids in Total Mix


Voids in Mineral Aggregates


Voids filed with Asphalt


32.85
32.80
32.75
32.70
32.65
32.60


54 56 58 6 62 64 66
%oAC


56 58 6 62
% AC


64 66


3900
3800
3700
36 00
35 00
S34 00
33 00
3200
31 00 -
3000
5


4 56 58


6 62 64 66
%AC


Figure 3-4. Mix Design of PFC Gradation (2) with aggregate type: Granite


Optimum Asphalt Content: 5.9% Gmm at Optimum Asphalt Content:- 2.491


Mineral Fiber: 0.4% of Total Mix VMA at Optimum Asphalt Content: 32.76%


Gmm1 = Maximum specific gravity of mixture, Gmb2 = Bulk specific gravity of mixture, VMA3 = Voids in Mineral Aggregates,


VTM4 = Voids in Total Mix, VFA5 = Voids filled with Asphalt, AC6 = Asphalt Content


2300

2200

2100

2000


i/









3.6.2 Asphalt Film Thickness

As granite has fine texture, the surface absorption is negligible, meaning that water

absorption (Waterab =0) can be assumed to be negligible. The surface areas calculated for

Gradation (1) and Gradation (2) are based on the method proposed by Nukunya et al

(2001 and discussed in Chapter 3. The resulting surface areas for Mixture 1 and Mixture

2 are 1.8 mA2/Kg and 1.78 mA2/Kg, respectively. Taking the total asphalt content for

both gradation as the effective asphalt content the film thickness is calculated by

following equation mentioned in recommended specification (Chapter 2):

Vy x1000
Tm = (2.3)
Sm SA x W
Where,

16. Wgg = Weight of aggregate
SA = Surface area

Gradation (1) has film thickness of 33.12microns where as Gradation (2) has of 31.65

microns. These film thicknesses for Gradation (1) and Gradation (2) are calculated

assuming zero asphalt absorption. Both film thicknesses are above the specified

minimum film thickness requirement, i.e. 32 microns, for 0% to 0.5% asphalt absorption.

The minimum film thickness requirement is to ensure resistance against stripping and

asphalt hardening.

3.7 Superpave IDT Performance Test Results

In the following, the results from the Superpave IDT fracture testing results are

presented. The basics of the Superpave IDT test equipment and data acquisition system

have been specified by Buttlar and Roque (1994), Roque et al., (1997), and AASHTO









TP-9. Additional information on the specific testing system used in this study is as

follows:

* An environmental chamber was used to control specimen temperature. The
chamber is capable of maintaining temperatures between -30 C and 300 C with an
accuracy of +0.10 C.

* Loads were controlled using a MTS Model 418.91 MicroProfiler.

* Vertical and horizontal deformation measurements were obtained using
extensometers designed by MTS specifically for use with the Superpave IDT. A
gage length of 1.5 inches was used for all specimens.

Since the friction course mixtures are very porous, it was decided that the sample

thickness be around 1.5 -2 inches in order to avoid end effects. A cutting device, which

has a cutting saw and a special attachment to hold the pills, was used to slice the pill into

specimens of desired thickness. Two two-inch samples were obtained from each

specimen. Because the saw uses water to keep the blade wet, the specimens were dried

for one day at room temperature to achieve the natural moisture content. Before testing,

the specimens were placed in the humidity chamber for at least two days to negate

moisture effects in testing.

Gage points were attached to the samples using a steel template and vacuum pump

setup and a strong adhesive. Four gage points were placed on each side of the specimens

at distance of 19 mm (0.75 in.) from the center, along the vertical and horizontal axes. A

steel plate that fits over the attached gage points was used to mark the loading axis with a

marker. This helped placing the sample in the testing chamber assuring proper loading of

the specimen.

Standard Superpave IDT tests were performed on all mixtures to determine resilient

modulus, creep compliance, m-value, D1, tensile strength, failure strain, fracture energy,

and dissipated creep strain energy to failure. The tests were performed at 100C. First,









resilient modulus test was conducted on specimen. Thereafter, specimen was allowed to

rest for 45 min, before creep test was conducted, in order to regain delayed elasticity.

The indirect tensile strength test was performed after the creep test.

3.7.1 Superpave Indirect Test Results and Analysis

Superpave fracture testing was conducted on both mixes prepared for Gradation (1)

and Gradation (2). Mixes were subjected to short-term oven aging. Even though, these

porous mixtures with air voids around 21% does not hold moisture, the specimens were

kept in dehumidifier for 48 hours before testing. The applied stress used for calculation of

Energy ratio is 88.23 psi. Georgia PEM fracture test results were used as a reference to

understand the mechanism of aggregate structure. Table 3-4 provides a summary of

fracture test results of Georgia PEM and 1-295 PFC project mixtures.

Figure 3-5 (a) through (i), show comparison of the Superpave IDT test results. The

parameters presented include: Energy Ratio, Fracture Energy, Dissipated Creep Strain

Energy, Failure Strain, Creep Compliance, Resilient Modulus, Strain Rate, Creep Rate

and Tensile Strength between Georgia PEM and PFC mixtures. Although, Gradation (1)

shows higher tensile strength, the Energy Ratio for Gradation (1) and Gradation (2) are

1.66 and 1.20 for Gradation (1) and Gradation (2) respectively. Because of reduction in

surface area and increase in volume of water permeable pores not absorbing asphalt there

should be increase in film thickness in Gradation (2) over Gradation (1). But, the

reduction in optimum asphalt content counteracted this effect. Hence the creep response,

which is a measure of the visco-elastic nature of asphalt, was about the same for both

gradations. The creep compliance of Gradation (1) is 17.53 (1/Gpa), which is comparable

with the creep compliance of Gradation (2) i.e. 18.07 (1/Gpa).












Table 3-4. Summary of Indirect Tensile Test performed on 1-295 PFC mixtures
88.23
Property Stress=

Creep Strain
Sample Resilient compliance Tensile Fracture Failure Elastic Rate
Modulusat 1000 StrengthEnergy Strain D1 10 ) E. per
alue (kJ/m^3) atio
(Gpa) seconds (Mpa) (kJ/mA3)(10-6) aue ((k/mA3) Unit
(1/Gpa) stress

Georgia 8.35E-
Georga 4.97 19.933 1.24 4.2 4383.20.74 35E4.05 4133.730.154 1.95 1.1E-07
PEM 07
Gradation 1.2E-
4.41 17.531 1.15 3.6 3940.10.66 3.45 3679.320.150 1.67 7.9E-08
(1) 06
Gradation 8.9E-
5.01 18.078 1.12 2.4 2742.3 0.71 2.27 2518.79 0.125 1.21 8.6E-08
(2) 07









Fracture Energy


I


I


Georgia Gradation Gradation
PEM (1) (2)

Failure Strain





1-


, 5.00 -
4.00
, 3.00 -
2.00
1.00
0.00


Georgia Gradation Gradation
PEM (1) (2)


Georgia Gradation Gradation
PEM (1) (2)


DCSE


I


I


Georgia Gradation Gradation
PEM (1) (2)


Creep Compliance


Georgia Gradation Gradation
PEM (1) (2)


Resilient Modulus

6
4-
3



Georgia Gradation Gradation
PEM (1) (2)


Tensile Strength


1.20E-09
1.00E-09
8.00E-10
. 6.00E-10
2.00E-10
O.OOE+00


1
Georgia
PEM


Gradation Gradation
(1) (2)


1.50
1.00
S0.50
S0.00
r


Georgia Gradation Gradation
PEM (1) (2)


G) H)
Figure 3-5. A)Energy Ratio, B) Failure Energy, C) Failure Strain, D) DCSE, E) Creep
Compliance, F) Resilient Modulus, G) Strain Rate, H) Tensile Strength, I)
Creep Rate


2.50
S2.00
1.50
S1.00
0.50


u.uu


S5000
' 4000
S3000
2000
0 looc


- 25
20
15
S10
5


Strain Rate


"1


-- !


Energy Ratio


I-










Creep Rate

S1.20E-09
1.00E-09
8.00E-10
6.00E-10
4.00E-10
2.00E-10
.0.00E+00
Georgia Gradation Gradation
PEM (1) (2)

Figure 3-5. Continued

Essentially, due to this reason, the resilient modulus of Gradation (1) and Gradation

(2) are 4.41 Gpa and 5.01 Gpa, respectively, which are comparable magnitudes for the

resilient modulus. The Georgia PEM had a creep compliance of 19.933 1/Gpa and a creep

rate of 1x10^-7 1/psi-sec, which implies that the arrangement of aggregate structure is

such that it is giving more room for mastic between coarse aggregate. This indicates the

aggregate arrangement and interaction of coarse and fine aggregate in mixes plays an

important role thus affecting the strength of Gradation (2) relative to Gradation (1).

3.8 Analysis of Fracture Result Based on Interstitial Volume and Aggregate Interaction

Ongoing work at the University of Florida has led to the establishment of a

tentative gradation selection framework for the optimization of the fracture resistance of

dense graded mixtures. Key concepts in this new proposed framework include the

observation that enhanced cracking resistance can be obtained by ensuring that the

aggregates in the course portion of the mixture gradation interact sufficiently amongst

each other to allow for the effective transfer of forces through the course-aggregate

portion of the mixture. This interaction of the course aggregate component should not

reach down to the finer materials, so as to control mixture sensitivity. The material

within the interstitial volume of the course aggregate portion also needs to be

proportioned and designed so that an adequate Dissipated Creep Strain Energy (DCSE)










limit is maintained, as well as providing enough flow and ductility to enhance the fracture

resistance of the mixture. Too little interstitial material, or interstitial material with a low

creep strain rate, will result in a brittle mixture. It is anticipated that these gradation

concepts will be transferable to Georgia-PEM mixtures, thus allowing for the

development of guidelines for the selection of gradations that optimize the resistance to

cracking.

3.8.1 Determination of Porosity and Interstitial Volume

In the following, the portion of the coarse aggregate for each of the three mixtures

will be evaluated, followed by a characterization of the interstitial volume component.

First, the aggregate interaction curve needs to be defined:

The Aggregate Interaction Curve: Aggregate interaction curve is plot of points of

interaction of aggregate size with its successive aggregate size. Following is equation

used for calculating points of interaction: -


% Retained Particle Interaction Point= (% Retained at Sieve Size) 100 (3.1)
(% Retained at Succesive Sieve Size + (% Retained at Sieve Size)


Aggregate Interaction Curve

S 100
90



k 40
S 830
20
10
0



Contiguous sizes, nun
--- Gradation (1) Georgia PEM + Gradation (2)

Figure 3-6. Curve showing interaction between contiguous aggregate sizes









Figure 3-6 shows the aggregate interaction curves for Georgia PEM and 1-295 PFC

projects. If the percent Retained Particle Interaction falls outside the range between 30%

and 70% the aggregates in that size range are not interacting. Therefore, aggregate sizes

below this break point are not interacting towards contribution of strength. These

aggregate sizes are filling the cavities between coarse aggregate above the break points.

The aggregate sizes below the break point along with asphalt are contributing to the

Interstitial Volume. The range of aggregate sizes above this break point between 30%-

70% is called the "Dominant Aggregate Size Range" (DASR).

Porosity: Porosity for this DASR represents the actual porosity for the total mix. It

is the ratio of summation of volume of air voids and effective asphalt in compacted mix,

to volume of DASR and below.

(Volume of Air Voids) + (Volume of Effective Asphalt)
Porosity = (3.2)
Volume of Aggregates 1i ihin DASR and below DASR)
Interstitial Volume: Mastic, comprising aggregate sizes below break point, asphalt

and air voids, forms the interstitial volume of compacted mixture. The interstitial volume

is the ratio of mastic in specimen to the total volume of compacted mixture.

(Volume of Mastic)
Interstitial Volume= (Volume f Mastic) (3.3)
Total Volume of Compacted _Mixture

The film thickness based on Interstitial Volume ( fiT): Calculation of surface area

is main issue of this method. As per the hypothesis discussed above, aggregates below the

break point (i.e. aggregates within the interstitial volume) contain all of the effective

asphalt volume, thus covering the coarse aggregate. The surface area (SA) of aggregates

below the break point is calculated using surface area factors tabulated in Table 3-7 are

calculated. As the absorption in granite is negligible, the total asphalt content is taken as

V W
effective asphalt content ( eff) of the compacted mixture. Weight of aggregates ( agg) in









air is taken into account for calculating film thickness. Equation 3-1 denotes calculation

of film thickness with in interstitial volume:

V x 1000
Tflm (3.4)
SA SA xW

Table 3-5. Surface area factors


Surface Area
Percent Area Surface Area
Sieve Size Percent Factor
Passing

ft.2/lb. m2/Kg ft2/Ib. m2/Kg
11/2 in.(37.5mm) 100
1 in. (25.0mm) 100
3/4 in. (19.0mm) 100
1/2 in. (12.5mm) 89
3/8 in .(9.5mm) 62 2.0 0.41
No.4 4.75mm 15 2 0.41 0.3 0.06


Aggregate Aggregate
with in with in
interstitial interstitial
volume volume



3.8.2 Analysis and Conclusion

The DASR of Gradation (1) and the Georgia PEM is 9.5-4.75 mm, resulting in

porosity of 46.29% and 49.51% respectively. Table 3-6 shows the porosity and interstitial

volume of all the three JMFs. Due to the interaction of 12.5 mm aggregate size with

successive aggregate size, the DASR of Gradation (2) is 12.5-4.75, resulting in a porosity

of 42.71%. As porosity is below 50% the mixes should perform well in strength.

Similarly, due to the relatively high interaction resulting in percent retained particle

interaction of 44.77 percent (see Figure 3-6) in the critical 9.5-4.75 range, the Georgia

PEM mixture is expected have a higher energy ratio than Gradation (1) and Gradation









(2), which had percent retained particle interaction of 35.55% and 34.85% respectively,

as shown in Figure 3-6.

Table 3-7 shows the interstitial volume for the three mixtures studied. The

interstitial volume of Gradation (1) and Gradation (2) is comparatively the same.

Therefore due to the same amount of interstitial volume component, for both gradations,

it is not surprising that both gradations result in a similar creep response.

Table 3-6. Porosity for all the dominant aggregate size ranges (DASR)
9.5mm 4.75mm 2.36 mm

Range 12.5-9.5 9.5-4.7512.5-4.75 4.75-2.369.5-2.3612.5-2.36

Gradation (1) 74.65 46.29 42.70 52.77 42.71 39.39
Georgia PEM 71.97 49.51 46.04 50.34 38.96 36.23
Gradation (2) 73.44 47.51 42.71 53.56 43.76 39.34

The Similarly, Georgia PEM results in a higher creep compliance and strain rate

due to the higher interstitial volume. Due to this reason, the DCSE threshold for

Gradation (1) and Gradation (1) is reduced to 2.27 KJ/mA3 and 3.45 KJ/mA3, respectively

from 4.05 Kj/mA3 for the Georgia-PEM granite.

Table 3-7. Interstitial Volume for different JMFs
Film Thickness
JMF Interstitial Volume (%) with in Interstitial
Volume (Microns)
Gradation (1) 42.70 33.12
Georgia PEM 46.04 54.58
Gradation (2) 42.71 31.65

In summary, it is not possible to differentiate between the fracture performance of

Gradation (1) and (2) at the low Superpave IDT test temperature of 10 C. Therefore, it

was recommended that Gradation (1) be selected since the FDOT contractor had already

obtained all necessary materials to run that mixture. The difference in fracture









performance between Gradations (1) and (2) did not justify the selection of Gradation (2)

over Gradation (1).

3.9 Verification of Locking Point of Selected Gradation for 1-295 PFC Project

According to Vardhan (2004) the compaction curve follows a logarithmic trend. To

identify the locking point, the rate of change of slope of compaction curve was used. The

stage, at which the rate of change of compaction was insignificant, was essentially the

point of maximum resistance to compaction. The locking point, i.e. 49, was identified as

the point at which two gyrations at same gradient of slope were preceded by two

gyrations at same gradient of slope. The gradient was taken up to four decimal places (as

shown in Table 3-8 for PFC-Granite mixture, Gradation (1)).

Table 3-8. Locking Point Based on Gradient of Slope
Number of
umer of Gradient of Slope
Gyration
39 0.0022
40 0.0020
41 0.0020
42 0.0019
43 0.0018
44 0.0017
45 0.0016
46 0.0015
47 0.0015
48 0.0014
49 (LP) 0.0014
50 0.0013


3.10 Summary and Conclusion

The optimum asphalt content for Gradation (1) and Gradation (2) were determined

at 6% and 5.9% respectively. The difference in fracture test parameters for both

gradations is not significant. As shown in Table 3-7, the coarser portion in Gradation (2)









was increased by 10% over that of Gradation (1), but the interstitial volume of both

mixtures was unchanged at 42.70%. Therefore, the creep response of both mixtures is

approximately the same. This implies that interaction between coarser and finer part of

gradation and aggregate arrangement plays important role in optimizing fracture

resistance.

Gradation (1) is recommended for construction of test section at 1-295 even though

both gradations are performing well, as the Gradation (1) is giving higher Energy Ratio,

and there was simply no justification for selecting Gradation (2) over Gradation (1).














CHAPTER 4
A PROPOSED NEW FRACTURE TEST FOR ASPHALT MASTIC

4.1 Purpose and Need

Analysis of 1-295 project mixture's fracture test results shows importance of

interstitial volume in the fracture performance of mixtures. Mastic within the interstitial

volume, which is comprised of asphalt and aggregates below the break point of the

'Aggregate Interaction Curve' likely has an impact on the creep and fracture response of

mixtures. Therefore, it is important to be able to study the tensile strength and the

fracture energy of the mastic component under direct tension loading conditions. This

chapter presents the preliminary design of a new mastic fracture test.

4.2 Background

A device for studying fracture initiation and crack growth in mortar was developed

by Mindess & Diamond (1980). This device was modified version of work developed by

Subramanian et al (1978) for study of crack growth in ceramics. The specimen

configuration used by Mindesss & Diamond (1980) was similar to the compact tension

described in ASTM E399 (1978): Plain-Strain fracture toughness of Metallic Material.

This device functions is such a way that cracking is induced under carefully controlled

conditions, so that the details of slow crack growth may be observed at high

magnification in the SEM at all stages in the cracking process. This device was

constructed to permit the testing of wedge-loaded compact tension. Using this device, the

process of cracking was observed in mortar specimens. It was found that the process of

crack extension in mortars is very complicated: the crack is tortuous, there is some









branch cracking, discontinuities in the cracks are observed, and there is some tearing

away of small bits of material in some areas of cracking. The results suggest that the

simple fracture mechanics models oversimplify the geometric features of the crack

extension process.

4.3 Specimen and Test Device Design

The basic idea for this test is that tension can be induced by penetrating a wedge

between two rollers that lie on steel rods that penetrate through the specimen. Figure 4-1

shows specimen with bearings mounted on steel rods and wedge in loading direction
























Figure 4-1. Model showing Specimen along with bearings fitted on steel rods and wedge
in loading direction.

The specimen is 32 mm long, 24 mm wide and 13 mm thick with a 13 mm long and

0.6 mm wide notch at loading side of specimen.

Two 3.10 mm diameter steel rods on either side of notch were cast into specimen

for applying load. Figure 4-2 and 4.3 show the geometry of the specimen. Steel rods are







69


placed at 6 mm distance from outer edge of specimen. Steel bearings were fitted on steel

rods to make friction less application of load on specimen through rods.

A notch is provided in the specimen to create a stress concentration and pre-define

the path of cracking. Also, without the notch, there is a slight possibility that cracks

initiate at the contact area between the steel rods and the mastic, rather than in the desired

center portion of the test specimen. The steel rods are extended for 6.5 mm over the

specimen surface at both the top and the bottom sides of the specimen in order to avoid

contact of bearing roller and the driving wedge with the specimen



.0 -----4,00----.-
















7D
St 3ee







1 ^ 3.10


Steel
Rods V- 11.70 -- .70


Figure 4-2. Plan view showing geometry of specimen











/\T
teer 6,5o
Rods




26.00 1300




Notch
6, 0




Figure 4-3. Front view showing geometry of specimen

The rate of loading is directly proportional to angle of wedge. As the wedge moves

in forward direction, the distance between the bearings is increasing gradually, causing an

increase in tension at the tip of the notch stress concentrator. Due to the roller bearings,

there is no friction associated with the load transfer from the wedge to the steel rods. A

mechanical system is required to propel the wedge in a forward direction. Mindess &

Diamond (1980) developed a device, which uses a screw system for the driving of the

wedge. Their test device is shown in Figure 4-4. It consists of a frame to support the

specimen and the loading wedge; the turning of a screw advances the wedge, such that

one complete rotation of the screw advances the wedge 0.64 mm. The screw feed is

activated through a pulley system driven by a small electric motor and a gearbox with a

reduction of 360:1. The motor is rated at 12 volts; by varying the voltage using a variable

power supply, different rates of motion of the wedge can be achieved. The overall

dimensions of the device are 82.6 mm long, 41.0 mm wide and 54.0 mm high.






























Figure 4-4. Testing Device used by Mindess & Diamond (1980) for SEM testing on
cement mortar

4.4 Formulation of Tensile Force Transfer from Wedge to Specimen

The rotary action of an electrical motor moves a screw through pulley action with

the help of a rubber belt. One complete rotation of this screw moves the wedge for 0.64

mm in direction towards notch. The load applied on the wedge can be measured by

placing a load cell at the back of the specimen. As it can be assumed that the complete

system is acting as a rigid body for the determination of the balance of external forces.

The load (P) on the specimen applied by wedge, is measured by a load cell located at the

end of the specimen.

In the following, the static analysis is presented for calculating horizontal thrust on

the steel rod due to wedge loading:









Taking Moment at point B, shown in Figure 4-5, results in:

x
-(P x ) + xx = 0 (4.1)

Solving for Va

x
Va xx = (P x )
2
P
Va = (4.2)
2
Where,

P = Applied load on wedge

Va = Vertical component of resultant 'Ra'

x = Horizontal distance between bearings

As the wedge moves in the y-direction, there is a change of distance 'x'. In the above

equation there is no affect of 'x'. The force components Va and Ha, shown in Figure 4-5

denote the the vertical and horizontal component of the reaction Ra. The angle 0 in

Equation 4-3 is the half angle of the wedge used to apply the load. Resolving forces in the

horizontal direction for equilibrium at point A results in:

H, =cos0 x R (4.3)

and Va = sinO x Ra (4.4)

Substituting Equation 4-2 into Equation 4-4, results in:

P
sin0 xR =R
2

Hence, solving for Ra results in:

P 1
Ra -x (4.5)
2 sin 0






73



P




------- -
7
\ /
\ /
1
Y
\ /
", /
Ha \ B Hb

S :\ /


/90-e 9/-e



Va Vb



x
X


Figure 4-5. Static analysis of force transfer from Wedge to Steel rods (Wedge angle =
2x0)

Finally, solving for H, by substituting value of Ra from Equation 4-5 to 4.3 results

in:

P 1
H = cos x x (4.6)
2 sin 0

This means that the wedge angle (0 x 2) is inversely proportional to horizontal thrust

Ha. Therefore, a small wedge angle will result in a high horizontal thrust, hence

minimizing the effect of the vertical component of the vertical force 'P'. However, a

small wedge angle requires a longer wedge to cause the same magnitude of horizontal









force (tensile force) than a large angle wedge. As this specimen is designed for compact

fracture testing on mastic, it may be desirable to keep the testing device as small as

possible. Therefore, it is recommended to make the wedge angle at least 4-5 degrees.

The final wedge designed for this study has has a wedge angle of 4.50, resulting in:

H, = 12.72 x P (For 0 = 2.250) (4.7)

Hence horizontal thrust is approximately 12 times P.

4.5 Verification of Stress States within Loaded Specimen

In order to verify the stress concentration at the notch and to ensure that the sizing

of the steel rods did not cause excessive bearing forces in the specimen, a finite element

analysis using ADINA was performed.

Considering the line of symmetry along the centerline of the notch, the specimen is

divided into two half, with only one half being analyzed with ADINA. Plain stress

analysis is done on 2-D model of specimen in ADINA by dividing the total surface in to

15 sub surfaces, shown in Figure 4-6. The isotropic linear elastic material finite element

analysis in ADINA is done on specimen. The critical section line is divided into 170

elements with last element to first element ratio 0.25. Figure 4-7 shows meshing of sub

surfaces divided. The modulus of steel adopted is 19GPa with Poisson ratio of 0.3 for the

finite element analysis. The modulus of asphalt mastic at temperature 100 C is taken 4

Gpa and poisons ratio was 0.18. Essentially, while executing plain stress finite element

analyses in ADINA the stress obtain at any section are irrespective to modulus.

In order to keep the problem general, all results below are presented in terms of

normalized loads. A horizontal thrust of 12.72 x P is applied at steel pin's center. In

ADINA, the load P is taken as P = 1, for simplicity. Therefore the Ha = 12.72 and Va =









0.5 from Equation 4-4 and Equation 4-7. Figure 4-8 shows the exaggerated deformation

of the 2-D model due to the effects of Ha and Va.















U U

F1 d i t 1
S24 S16




S 25:: j




Figure 4-6. Specimen 2-D Model subdivided in to 15 surfaces







76









317

















Figure 4-7. Meshing of 15 sub surface with critical model line divided into 175 elements.





DISP MAG 166

17





B V
C-


Figure 4-8. Deflection of Specimen's 2-D Model subdivided.









The predicted stress (oyy) distribution along the centerline of the specimen is

shown in Figure 4-9. As expected, the maximum stress is found at the tip of notch

(oyy = 273 x P/ mm2), which confirms the stress concentration effects of the

notch.


Stress (6yy) Distribution from tip of Notch along center of specimen

300.00

250.00 Stress at Tip of
I \Notch 273 P/mm^2
< 200.00

S150.00

S100.00

50.00

0.00

-50.0o0 0 0.70 0.90 1.10 1.30 1.50 1.70 1.90 2.10

Coordinate distance (mm)


Figure 4-9. Stress distributions along centerline of specimen Tensile stress is shown as
positive.

Figure 4-10 shows the distribution of stresses (oyy) along the circumference of the

steel pins at contact with the mastic. The normalized stress distribution is a function of

the load "P" which is applied to the wedge. Part of this contact surface facing loading is

in compression. As the steel pin is loaded, the surface behind the loading area develops

tension. Due to the observed stresses at the tip of notch being substantially higher than

stresses at the contact surface between the mastic and the steel pins, the initiation of crack

is much more likely to be at the tip of the notch.




































Figure 4-10. Stress distribution along circumference of steel pin



4.6 Sample Preparation Guidelines

Aggregates contributing to the interstitial volume below the break point in the

aggregate interaction curve, discussed previously in section 5.5.1, are mixed with total

asphalt content of the 1-295 PFC mixture for preparing the mastic.

Table 4-1 shows the proportion of the aggregate gradation below the breakpoint for

the 1-295 PFC mixture that is mixed with the 6 percent asphalt by weight of the total

mixture (see Chapter 5 for mixture design details).


Stress distribution along circumference of Steel Pin

30.00

20.00

< 10.00

0 0.00

10.00

-20.00

-30.00


Circumferential distance (mm)









Table 4-1. Part of fine aggregates to be mixed with total asphalt content (6%) of 1-295
PFC project


Sieve Size


11/2 in. (37.5mm)
1 in. (25.0mm)
3/4 in. (19.0mm)
1/2 in. (12.5mm)
3/8 in .(9.5mm)


F-
Aggregate
within
interstitial
volume


Aggregate
within
interstitial
volume


The aggregates and asphalt binder are heated to 3300 F 3.5 o F (1650 C 3.5F)

for 2 hours before mixing. The aggregates are mixed with the asphalt binder using

equipment as specified in AASHTO T-209-99 (2004) for mixing. The prepared mastic is

molded into the desired shape, using a mold shown in Figure 4-11. Figure 4-12 shows

geometry of main base plate to which side plates are attached. As the asphalt tends to

bulge inside after cooling at the surface in contact with air, it is recommended that the

mastic should be filled to a level slightly above the mold surface. The mold in Figure 4-

10 is designed to provide a flat surface for trimming the excess mastic. First fit the steel

pins and then assemble the mold into the groves of the bottom base plate and notch plate.

Then, the top base plate is fitted on top and all bolts are screwed into position for a tight

mold.











A '-


Figure 4-11. Mold for preparing specimen for Fracture and SEM testing


Figure 4-12. Geometry of main base plate to which side plates are attached


~G~






81


4.7 Recommendation for Further Development

Further work needs to be done for developing a test device and deformation

measurement system. The following recommendations should be considered in further

development:

* A trial test specimen needs to be molded using the mold shown in Figure 4-11 to
check workability.

* A wedge angle within the range of 4% to 5% to obtain maximum horizontal thrust
with optimum wedge length, is recommended.














CHAPTER 5
PERFORMANCE TEST DATABASE (PTD)

5.1 Preface

This program was developed to store and analyze data from performance testing of

mixtures (Performance Test Database: PTD). The program is entirely interactive. It

is set up for easy navigation from one part of the program to another. The functionalities

included are: 1) data input, 2) data extraction, 3) data export to database, 4) data analysis,

and 5) report generation. All the instructions for using the tutorial are available in the

help menu and user's manual in order to work with the program's interface.

Program details in this manual are provided for system administrators or

programmers that want to understand its architecture and design, to extend or modify

the PTD.

5.1.1 Package Information

This package for the PTD contains the following:

a) The User's Manual.

b) One set of CDs labeled PTD

The User's Manual contains information on how to operate the program and how to

execute the commands. It also describes terminology behind programming and provides

details of algorithms developed for specific task.









5.1.2 System Requirements

The minimum requirements for successfully executing the PTD program are:

a) Windows2000/Me/Xp or later.

b) 64 MB RAM.

c) Hard disk with 2.5 MB of free space.

The PTD program may be installed either onto a hard-disk system or onto a

network computer system, and can also be easily uninstalled by using the provided

installation software.

5.1.3 Supported Output Format Requirement

The P.T.D. supports multiple report output formats. All reports are generated in a

native Access format which is transformed into other output formats by Visual Basic

commands. The following formats are supported :

Print

This output format requires a computer system connected to a printer. This format

uses default printer settings. The report is printed directly using this option.

Rich text format

This format creates word file with a rich text format extension (.rtf) at a user

specified directory. Image characters of the report are not retained in this output format.

Email

This output format provides the means to export a report to other systems through

email. An automated function is used to send a report as an attachment to an email. This

option requires that the Microsoft Outlook SendmailTM be activated. There is an option to

choose the format of the report from the Rich text format, Snapshot format, Microsoft

Excel Format, HTML, and MS-Dos text format.









The rich text, Snapshot and HTML formats are preferred as original alignment is

maintained in the extracted data.

5.2 Program Overview

The Superpave Indirect Tensile Test at Low Temperatures (ITLT) computer

program can be used to analyze test data obtained from the Superpave Indirect Tensile

Test. The ITLT program generates five text files, which have the following extensions: -

.MRO, .FAM, .OUT, .IN an .STR files. For input into the PTD database, the Data from

these text files need to be extracted, analyzed and stored for a future reference. This

database is designed with an aim to not only store performance test data, but also to keep

track of the findings and analysis of different mix design and performance test on various

materials. Extracted data from text files is reformatted in order to make storage easier in

the database. The included search engine makes allows the user to customize desired

queries of data and analysis results. The data and analysis results categorized according to

the search criteria are then reported through report generation.

Visual basic for Excel Applications was used to automate the process of data

extraction and formatting in a tabular form. The flowchart in Figure 5-1 provides a

complete overview on the flow of data from raw data files to storage, analysis, and final

report generation.

All the test readings from text files are inputted into an Excel file. There is

interface, which is developed in visual basic that has categorized option for each set of

test data for extracting data from text file.




Full Text

PAGE 1

DEVELOPMENT AND EVALUATION OF PE RMEABLE FRICTION COURSE MIX DESIGN FOR FLORIDA CONDITIONS By LOKENDRA JAISWAL 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 2005

PAGE 2

Copyright 2005 by Lokendra Jaiswal

PAGE 3

This document is dedicated to my parents.

PAGE 4

ACKNOWLEDGMENTS I wish to specially thank Dr. Bjorn Birgisson and Dr. Reynaldo Roque for their guidance and understanding throughout the project. I believe that their technical knowledge and personal advice helped me to achieve this milestone in my life and career. I really appreciate advice I received from Georg Lopp throughout my research work and for making thing work in laboratory. Thanks go to Dr. Christos Drakos, Georg Lopp and Greg Sholar for reviewing Performance Test Database (P.T.D.) software and making helpful suggestions, and also to the anonymous referees for many insightful comments. I would like to thank Alvaro and Tung for their assistance in performing various laboratory tests. I would like to thank Greg Sholar and Howie Mosely from the FDOT research wing for their help during the course of the project. Thanks go to Jaeseung, Sungho and Jianlin for there suggestion in finite element analysis. I would like to thank all my friends for providing an unforgettable and enjoyable time during my two years of study in Gainesville. Finally, I would like to thank my parents and my aunt and uncle for all the love and support they have given me throughout my academic years. iv

PAGE 5

TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iv LIST OF TABLES.............................................................................................................ix LIST OF FIGURES...........................................................................................................xi ABSTRACT.......................................................................................................................xv CHAPTER 1 INTRODUCTION...................................................................................................1 1.1 Background..................................................................................................1 1.2 Objectives....................................................................................................2 1.3 Scope............................................................................................................2 1.4 Research Approach......................................................................................3 2 DEVELOPMENT OF MIX DESIGN PROCEDURE FOR POROUS FRICTION COURSE..............................................................................................5 2.1 Initial Study and Objectives.........................................................................5 2.2 Georgia PEM Mixture Design as per GDT 114 Test Method: B (1996).....6 2.3 Overview of Evaluation of Preliminary OGFC/PFC Mix design Procedure Developed by Vardhan (2004)....................................................9 2.3.1 Determination of Compaction level for PFC...................................9 2.3.2 OGFC/PFC Mixture Design Procedure Proposed By Varadhan (2004).............................................................................................12 2.3.3 Long-Term Oven Aging Procedure Proposed for PFC Mixture by Varadhan (2004).......................................................................14 2.4 Verification of Florida Permeable Friction Course Mixture Design.........15 2.4.1 Materials........................................................................................15 Aggregate and gradation selection.................................................15 Binder and mineral fiber................................................................16 2.4.2 Sample Preparation for Determination of Optimum Asphalt Content...........................................................................................17 2.4.4 Mixing and Compaction of Samples for Determination of Bulk Specific Gravity.............................................................................18 2.4.4 Determination of Optimum Asphalt Content.................................20 v

PAGE 6

2.5 Evaluation of Film Thickness Criterion in PFC Design............................24 2.5.1 Review of Asphalt Film Thickness Calculation Methods.............27 2.5.2 Comparison of Results Obtained from Each Film Thickness Calculation Method........................................................................34 2.5.3 Relative Minimum Film Thickness Requirement..........................36 2.6 Recommended Specification for PFC Mixture Design.............................39 2.7 Conclusion of Verification of PFC mixture Design Procedure.................44 3 EVALUATION OF I-295 PFC MIX DESIGN.....................................................45 3.1 Objective....................................................................................................45 3.2 Scope of Project.........................................................................................45 3.3 Materials used for I-295 PFC project.........................................................46 3.3.1 Aggregate and Hydrated Lime.......................................................46 3.3.2 Binder and Mineral Fiber...............................................................46 3.4 Location of Project.....................................................................................48 3.5 Specification and Hypothesis Used...........................................................49 3.6 Determination of Optimum Asphalt Content.............................................50 3.6.1 Mixing and Compaction................................................................51 3.6.2 Asphalt Film Thickness.................................................................55 3.7 Superpave IDT Performance Test Results.................................................55 3.7.1 Superpave Indirect Test Results and Analysis...............................57 3.8 Analysis of Fracture Result Based on Interstitial Volume and Aggregate Interaction.................................................................................60 3.8.1 Determination of Porosity and Interstitial Volume........................61 3.8.2 Analysis and Conclusion................................................................63 3.9 Verification of Locking Point of Selected Gradation for I-295 PFC Project........................................................................................................65 3.10 Summary and Conclusion..........................................................................65 4 A PROPOSED NEW FRACTURE TEST FOR ASPHALT MASTIC.................67 4.1 Purpose and Need......................................................................................67 4.2 Background................................................................................................67 4.3 Specimen and Test Device Design............................................................68 4.4 Formulation of Tensile Force Transfer from Wedge to Specimen............71 4.5 Verification of Stress States within Loaded Specimen..............................74 4.6 Sample Preparation Guidelines..................................................................78 4.7 Recommendation for Further Development..............................................81 5 PERFORMANCE TEST DATABASE (PTD)......................................................82 5.1 Preface........................................................................................................82 5.1.1 Package Information......................................................................82 5.1.2 System Requirements.....................................................................83 5.1.3 Supported Output Format Requirement.........................................83 5.2 Program Overview.....................................................................................84 vi

PAGE 7

5.2.1 Database Storage Outline...............................................................86 5.2.2 Software Coding Architecture and Program Flow.........................87 5.3 Installation..................................................................................................88 5.4 Users Manual............................................................................................89 5.4.1 Interaction to All Interfaces of Database.......................................89 5.4.2 Button Function.............................................................................90 5.4.3 Data Entry......................................................................................91 5.4.4 Navigation through Input Templates and Database.......................97 5.4.5 Data transfer to Database...............................................................97 5.4.7 Report Generation........................................................................102 5.4.8 Repair and Remove Program.......................................................103 5.5 Summaries and Recommendation............................................................103 6 MOISTURE CONDITIONING ON I-295 PFC PROJECT................................105 6.1 Objective..................................................................................................105 6.2 Scope........................................................................................................105 6.3 Materials and Methodology.....................................................................106 6.3.1 Aggregate and Hydrated Lime.....................................................106 6.3.2 Binder and Mineral Fiber.............................................................106 6.4 Specimen Preparation and Testing...........................................................107 6.4.1 Mixing and Determination of Asphalt Content...........................108 6.4.2 Volumetric Properties..................................................................109 6.4.3 Moisture Conditioning and Testing.............................................109 6.5 Fracture Test on Moisture condition........................................................112 6.5.1 Findings and Analysis..................................................................113 6.6 Summary and Conclusion........................................................................117 7 SUPERPAVE IDT FRACTURE TEST RESULTS............................................118 7.1 Materials..................................................................................................118 7.1.1 Aggregate and Hydrated Lime.....................................................118 7.1.2 Binder and Mineral Fiber.............................................................119 7.2 Test Method.............................................................................................120 7.2.1 Sample Preparation......................................................................120 7.2.2 Testing Equipment.......................................................................121 7.2.3 Specimen Preparation and Testing Procedure.............................123 7.2.4 Test Procedures and Analysis of Test Results.............................124 7.2.5 Results of Fracture Testing on PFC Mixtures..............................131 7.3 Summary and Conclusion........................................................................139 APPENDIX A SAMPLE CALCULATION OF VOLUMETRICS FOR GPEM AND PFC MIXTURE...........................................................................................................140 vii

PAGE 8

B MAIN PROGRAMMING CODE OF PERFOMANCE TEST DATABSE (P.T.D.)................................................................................................................145 C EFFECTIVE ASPHALT CONTENT CALCULATION FOR FILM THICKNESS DETERMINATION.....................................................................153 D GEOMERTIC DETAILS OF FRACTURE TEST SPECIMEN AND MOLDS FOR ASPHALT MASTIC...................................................................................155 E VOLUMETRIC PROPERTIES OF MIXTURES...............................................161 F JOB MIX FORMULA.........................................................................................164 LIST OF REFERENCES.................................................................................................165 BIOGRAPHICAL SKETCH...........................................................................................167 viii

PAGE 9

LIST OF TABLES Table Page 2-1 Gradation specifications according to GDT 114 (1996)............................................7 2-2 Locking Point Based on Gradient of Slope (Varadhan, 2004).................................11 2-3 Locking Points of all Mixtures based on Gradient of Slope (Varadhan, 2004).......11 2-4 Composition of GPEM-Limestone gradation JMF..................................................16 2-5 Composition of GPEM-Granite gradation JMF.......................................................16 2-6 Material quantities....................................................................................................20 2-7 Surface Area Factor Hveem (1991).........................................................................28 2-8 Surface area Factor suggested by Nukunya (2001) for coarse aggregate structure.29 2-9 Surface area factors for Interstitial Volume.............................................................31 2-10 CoreLok calculation Sheet.......................................................................................33 2-11 Comparison of Film Thickness method for Limestone mixture..............................35 2-12 Comparison of Film Thickness method for Granite mixture...................................35 2-13 JMF of Optimum gradation for Gradation limits as per GDT 114 (1996)...............38 2-14 Minimum film thickness requirements for different set of Asphalt absorption.......39 2-15 Proposed Gradation and Design specifications for Florida Permeable....................40 2-16 Surface area factor as per Nukunya et al (2001)......................................................43 2-17 Minimum Effective Film Thickness Requirements.................................................43 3-1 JMF composition of Gradation (1)...........................................................................47 3-2 JMF composition of Gradation (2)...........................................................................47 3-3 PFC Gradation Design Range from FDOT specification SECTION 337................49 ix

PAGE 10

3-4 Summary of Indirect Tensile Test performed on I-295 PFC mixtures....................58 3-5 Surface area factors..................................................................................................63 3-6 Porosity for all the dominant aggregate size ranges (DASR)..................................64 3-7 Interstitial Volume for different JMFs.....................................................................64 3-8 Locking Point Based on Gradient of Slope..............................................................65 4-1 Part of fine aggregates to be mixed with total asphalt content (6%) of I-295 PFC project.......................................................................................................................79 5-1 Buttons and there corresponding function...............................................................91 6-1 Gradation of I-295 PFC Project.............................................................................106 6-2 Summary of fracture test on moisture condition sample compared with unconditioned sample.............................................................................................115 7-1 Summary of Fracture Test results on Short-Term and Long-Term Oven Aged Mixtures of Georgia PEM, PFC Project and OGFC Mixture................................134 A-1 Gradation for Georgia PEM-Granite......................................................................140 A-2 Bulk Specific Gravity for Georgia PEM-Granite...................................................140 A-3 Rice Test for Georgia PEM-Granite.......................................................................141 A-4 Drain-down Test for Georgia PEM-Granite...........................................................141 A-5 Film Thickness for Georgia PEM-Granite.............................................................142 C-1 Core-Lok Results calculation for Efffective asphalt content.................................154 C-2 Minimum Film Thickness......................................................................................154 E-1 Volumetric Properties of all the Mixtures..............................................................162 F-1 Composition of Job Mix Formula of FC-5 Limestone...........................................164 F-2 Composition of Job Mix Formula of FC-5 Granite................................................164 x

PAGE 11

LIST OF FIGURES Figure Page 1-1 Flow chart showing Research Approach implemented...........................................4 2-1 Gradation Band with in GDT 114 (1996) specified gradation limits used by Varadhan (2004)....................................................................................................13 2-2 Georgias Permeable European Mixture gradation band.......................................17 2-3 Example of determination of inconsistent optimum asphalt content.....................18 2-4 Mix Design of OGFC with aggregate type: Limestone.......................................22 2-5 Mix Design of OGFC with aggregate type: Granite............................................23 2-6 Aggregate Structure for Coarse and Fine Mixtures (Nukunya et al. [2001])........25 2-7 (a) Granite with high film (Required against stripping) (b) Limestone with low film thickness as compared with granite due to absorption...................................34 2-8 Optimum Gradation Band for Calculating Minimum film thickness requirement............................................................................................................38 2-9 Proposed Gradation limits for Florida Permeable Friction Course Mixtures........41 3-1 Gradation of I-295 PFC mixtures..........................................................................47 3-2 Project Location.....................................................................................................48 3-3 Mix Design of PFC Gradation (1) with aggregate type: Granite........................53 3-4 Mix Design of PFC Gradation (2) with aggregate type: Granite........................54 3-5 A)Energy Ratio, B) Failure Energy, C) Failure Strain D) DCSE, E) Creep Compliance, F) Resilient Modulus, G) Strain Rate, H) Tensile Strength I) Creep Rate..............................................................................................................59 3-6 Curve showing interaction between contiguous aggregate sizes...........................61 4-1 Model showing Specimen along with bearings fitted on steel rods and wedge in loading direction................................................................................................68 xi

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4-2 Plan view showing geometry of specimen.............................................................69 4-3 Front view showing geometry of specimen...........................................................70 4-4 Testing Device used by Mindess & Diamond (1980) for SEM testing on cement mortar........................................................................................................71 4-5 Static analysis of force transfer from Wedge to Steel rods (Wedge angle = 2x ).......................................................................................................................73 4-6 Specimen 2-D Model subdivided in to 15 surfaces...............................................75 4-7 Meshing of 15 sub surface with critical model line divided into 175 elements....76 4-8 Deflection of Specimens 2-D Model subdivided.................................................76 4-9 Stress distributions along centerline of specimen Tensile stress is shown as positive...................................................................................................................77 4-10 Stress distribution along circumference of steel pin..............................................78 4-11 Mold for preparing specimen for Fracture and SEM testing.................................80 4-12 Geometry of main base plate to which side plates are attached............................80 5-1 Flow chart showing extraction and input sequence of Indirect Tensile Test Data........................................................................................................................85 5-2 Flow chart showing data input of Complex Modulus test.....................................88 5-3 Installation Screen..................................................................................................89 5-4 Main Interaction Template.....................................................................................90 5-5 Input template options............................................................................................92 5-6 MS-DOS Base text file input template..................................................................93 5-7 Input dialog box.....................................................................................................94 5-8 Save changes dialog box........................................................................................95 5-9 Decision Box for clipboard changes......................................................................95 5-10 Applied tensile stress input box.............................................................................96 5-11 Database Main Menu.............................................................................................97 5-12 Database Input Mask..............................................................................................98 xii

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5-13 (a) Correct state of input tables for data entry.......................................................98 5-13 (b) Incorrect state of input tables for data entry.....................................................98 5-13 (c) Right click projected arrow for opening paste option......................................99 5-13 (d) Dialog box: After selecting paste option. Opt Yes.....................................99 5-14 Search dialog box Select type of search............................................................100 5-15 Search form..........................................................................................................101 5-16 Search Result Form..............................................................................................101 5-17 Report delivery option.........................................................................................102 5-18 Email Report........................................................................................................103 6-1 Plot of I-295 PFC mixtures gradation.................................................................107 6-2 Mix Design of I-295 PFC-Granite mixture..........................................................111 6-3 Compacted pill rolled in 1/8 inch sample placed in vacuum chamber..............112 6-4 Vacuum Saturation of sample prior to moisture conditioning.............................112 6-5 Affect of conditioning over stone to stone contact of PFC mixtures...................114 6-6 Comparison of Fracture Test rsults A) Energy ratio, B) Fracture energy, C) Tensile strength, D) Failure strain, E) DCSE, F) Creep compliance, G) Resilient modulus, H) Strain rate, I)Creep rate....................................................116 7-1 Gradation Band of Georgia PEM and I-295 PFC Project....................................119 7-2 IDT testing device................................................................................................122 7-3 Temperature controlled chamber.........................................................................122 7-4 Typical Dense-Graded specimen with extensometers attached...........................123 7-5 Dehumidifying chamber......................................................................................124 7-6 Power Model for Creep Compliance...................................................................129 7-7 FE and DCSE from Strength Test........................................................................131 7-8 Energy Ratio........................................................................................................135 7-9 Fracture Energy....................................................................................................135 xiii

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7-10 Failure Strain........................................................................................................136 7-11 DCSE...................................................................................................................136 7-12 Resilient Modulus................................................................................................137 7-13 Creep Compliance................................................................................................137 7-14 Strain Rate............................................................................................................138 7-15 Power Model Parameter (D1)..............................................................................138 7-16 Power Model Parameter (m)................................................................................139 A-1 Final Mix Design for Georgia PEM-Granite.......................................................144 D-1 Showing 3-D view of mold designed for preparing specimen for Asphalt Mastic...................................................................................................................156 D-2 Base plate 3-D wire view showing position of groves and notch........................157 D-3 Base plate geometry.............................................................................................158 D-4 Notch plate 3-D wire view...................................................................................159 xiv

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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Engineering DEVELOPMENT AND EVLUATION OF PERMEABLE FRICTION COURSE MIX DESIGN FOR FLORIDA CONDITIONS By Lokendra Jaiswal August 2005 Chair: Bjorn Birgisson Cochair: Reynaldo Ray Major Department: Civil and Coastal Engineering A mix design procedure for Permeable Friction Course that provides guidance on material properties, aggregate gradation, determination of optimum asphalt content, and mixture properties is needed for Florida conditions. This project involves 1) development of permeable friction course mix design procedure for Florida conditions, 2) evaluation of permeable friction course of I-295 project, 3) development of data extraction, analysis and database software for material properties, indirect tensile test results, and complex modulus test results, and 4) development of fracture test on sand asphalt for SEM analysis and tensile strength. In the course of study an extensive literature review was done on various mix design approach, material characteristics, and laboratory process guideline. Sample preparation and testing are carried in the laboratory for granite and limestone aggregate permeable friction course for determination of optimum asphalt content, moisture conditioning and long-term oven aging. An indirect tensile test is done xv

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on specimen with optimum asphalt content to evaluate performance of mixture. Film thickness, an important criterion for permeable friction course for ensuring resistance against stripping and asphalt hardening, is developed, based on the different absorption capacity of aggregate. This proposed mix design procedure was used to design PFC mixture for the I-295 project. Performance test database (PTD.exe) as data analysis and data storage software was developed using visual basic as the programming language. This software was used throughout the project for analyzing the test results and storing in database for future reference. Based on analysis of fracture test results of the I-295 PFC project, essentiality of fracture test on sand asphalt came up. A framework of fracture test on sand asphalt which can be conducted within SEM chamber is done. Observation of fracture test results of moisture conditioned sample of I-295 PFC mixture showed that coarse stone to stone contact is affected due to conditioning. Creep response of mixture remains approximately same after conditioning as compared with unconditioned sample. Finally, specifications and mix design procedure for PFC mixture are recommended and recommendations for further development of sand-asphalt fracture test are provided. Fracture test results FC-5 granite and FC-5 limestone samples, both aged and unaged, are compared with mixture designed for GPEM development and I-295 PFC project. xvi

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CHAPTER 1 INTRODUCTION 1.1 Background Porous Friction Course (PFC) improves the frictional resistance of pavements, along with the drainage of water, for reducing the potential of aquaplaning. In the 1990s the traditional FC-2 friction course developed by Florida was replaced by coarser open graded friction course (FC-5) which is -inch Nominal Maximum Aggregate Size (NMAS), placed approximately -inch thick. Even though the FC-5 had coarser aggregate structure and additional water storage capacity as compared to the old FC-2, water ponding on pavement surfaces continued to be a problem. Many states in US developed porous friction courses to over come such problems. The Georgia DOT developed their porous friction course design by utilizing a gap-grading aggregate and lowering the percentage of filler, following European PFC mixture designs. The combination of gap grading, low filler, and high asphalt content lead to the draining of asphalt binder from mixture during transportation and lay down procedure. Due to this problem, the Georgia DOT introduced mineral fibers in Georgia PEM mixtures. This research project is focused to develop and evaluate the Georgia PEM (GPEM) mix design procedure for Florida conditions, and updating the GPEM mix design by introducing Superpave gyratory compaction. Also, in the course of this project two other important developments are accomplished. First, a Performance Test Database (PTD) was developed to facilitate data analysis and data storage of mixture design and 1

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2 performance test results. The second achievement is the preliminary design of a new fracture test for asphalt mastic. 1.2 Objectives The primary objectives of the research are summarized below: Open Graded friction course because of their macro texture and air voids may not have enough water storage capacity for some applications, and may also be susceptible to stripping. The rate of susceptibility depends on climatic conditions. Therefore the development and evaluation of mix design procedure for Porous Friction Course (PFC) for Florida Climatic Condition is main objective of this research project. Mix design for a test strip on I-295, containing a Porous Friction Course (PFC) mixture design developed in this research project. Developing data analysis and database software, to store data from Fracture Test and Complex Modulus Test. Developing basics framework of fracture test for asphalt mastic. 1.3 Scope Mix design for I-295 highway (PFC project) provides an excellent opportunity to use and implement mix design procedure developed for GPEM. Database developed for data analysis and data storage is an excellent tool for referring previous mixture properties and their performance, while selecting gradation and doing mix design .Fracture test done on various field and lab prepared mixes enlightens many factors affecting the fracture resistance of mixtures. These factors are discussed individually in this thesis. It is always assumed that coarse aggregate are mainly responsible for contribution towards fracture resistance. Steps taken to develop fracture test on sand asphalt provides view on the contribution of fines and binder towards fracture resistance.

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3 1.4 Research Approach A detailed literature review was performed previously by Varadhan (2004) to understand Georgias mix design procedure. Figure 1-1 shows a flow chart of the approach adopted for this research. The Georgia DOT used Marshalls blow for mix design of PFC. This research introduced the Superpave Gyratory Compactor. Therefore, a primary objective was to determine number of gyration required to attain compaction level same as field compaction. Second step was to determine film thickness corresponding to this compaction level. Different methods of determining film thickness are carried out and then most optimize method is selected for mix design procedure. Superpave Indirect tensile test were carried out on Short Term Oven Aged (STOA) and Long Term Oven Aged (LTOA) mixtures for determination of facture resistance. Simultaneously, analysis and database software was developed in order to analyze and store data from this project. Once the mix design procedure was finalized a section of I-295 highway is designed based on this mix design method. Two trial gradations (JMF) were selected with in control points and mix design was carried on both of these gradations to determine optimum asphalt content. Final selection of gradation was done based strength and energy ratio criteria. Fracture testing was carried on all STOA and LTOA samples from US highways27 and I-295 PFC project. In the course of the project necessity of sand asphalts fracture resistance lead to develop new fracture test.

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4 Figure 1-1. Flow chart showing Research Approach implemented Reference of database during Mix design Data in p u t Mix Design of Porous Friction C ourse (I-295 PFC project) based performance test Selection of two trail grad ation M i x D e s i gn Indirect Tensile Test Selection of gradation based on energ y r a tio Development an d evaluation of mix design pro c edure of GPEM for Florida Condition. Determ inat ion o f Com p action L e vel Developm ent o f Film Thickn ess Criterion Determ inat ion o f aging eff e c t of F r acture T e s t Developm ent o f P e rform ance Tes t Database Data Extr act ion and Anal ysis Anal yzed da ta s t or ed in database Data entr y of PFC mixtures in d a tabase for referen ces Develop m ent of fracture test o n as p hal t Fracture testing on sample s (STOA and LTOA) from I-295 PFC project and GPFC samples Data input Thesis Literatur e R e view: Stud y o f pr evious work done and finalizing ob jectiv es to be achieved. Res earch Appro ach

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CHAPTER 2 DEVELOPMENT OF MIX DESIGN PROCEDURE FOR POROUS FRICTION COURSE 2.1 Initial Study and Objectives The Georgia Department of Transportation started evaluation of Porous European Mix (PEM), a form of Porous Friction Course Mixture, in 1992 for development a mix design for Porous Friction Course (PFC), which is entitled for Georgia Permeable European Mixture. Georgia PEM mixtures proved to be more permeable than conventional OGFC, due to its gap-graded characteristics, with a predominant single size coarse aggregate fraction that contains high percentage of air voids as specified by Watson et al. (1998). The Georgia PEM mix design (GDT 114, 1996) was used as a starting point for the new Florida Permeable Friction Course (PFC) mixture design. In the following, the GPEM mixture design developed by the Georgia DOT will be reviewed briefly, followed by the development of a new Florida PFC mixture design, which is based on the GPEM mixture design. Main objective of the Permeable Friction Course Design is to design a highly permeable mixture with good durability characteristics, while also providing sufficient mixture stability through coarse stone to stone contact. In order to enhance durability, it is desirable to have a high asphalt content, while preventing the drain down of binder, thus providing sufficient binder film thickness. Once the coarse aggregate contact structure is chosen, the design asphalt content is obtained by selecting four (4) trial mixtures of varying asphalt contents, and choosing the asphalt content that results in a minimum 5

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6 VMA. This is done to ensure reasonably high asphalt content. Importantly, it is necessary to use four trial asphalt contents, rather than three. Choosing only three asphalt contents will always result in one of the chosen asphalt contents to show a minimum, whereas choosing four asphalt contents will result in a true minimum that can be verified. The objectives of this chapter is to develop a Porous Friction Course (PFC) mixture design for Florida conditions and materials using the Superpave gyratory compactor, and to evaluate the new PFC mixture design using two mixtures that contain aggregates and asphalt that are typical to Florida. The Georgia PEM mixture design is used as a starting point for the development of the Florida PFC mixture design. 2.2 Georgia PEM Mixture Design as per GDT 114 Test Method: B (1996) In the following the Georgia DOT GPEM mixture design will be reviewed and used as a starting point for the Florida PFC mixture design approach. The first and foremost change was the introduction of the Superpave gyratory compaction into the mixture design in lieu of the Marshall compaction used by Georgia DOT. The main elements of the Georgia PEM mixture design are as follows: Georgia DOT GPEM mixture design method (GDT-114 Test Method: B, 1996) specifies the use of modified asphalt cement (PG 76-22) as specified in Section 820 (GDT 114,1996) and does not require the determination of surface capacity (KC) to determine initial trial asphalt contents. The Georgia DOT uses the Marshall Method of compaction during the design of the Georgia PEM mixtures. A stabilizing fiber is added to mixture for avoiding binder drain down, which meets the requirement of Section 819 (GDT 114, 1996). In the following, the steps in the Georgia PEM mixture design (GDT-114 Test Method: B, 1996) are listed. Table 2-1 shows gradation limits as GDT 114 (1996). A. SCOPE OF GPEM MIXTURE DESIGN

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7 The Georgia DOT method of design for a modified open graded bituminous GPEM mixture consists of four steps. The first is to conduct a modified Marshall mix design (AASHTO T-245) to determine asphalt cement content. The second step is to determine optimum asphalt content. The third step is to perform a drain down test, according to GDT-127 (2005), or AASHTO T 305-97 (2001). The final step is to perform a boil test, according to GDT-56, or ASTM D 3625. Table 2-1 gives gradation limits and design requirement for Open Graded Friction Course (For 9.5 mm and 12.5 mm Gradation) and Permeable European Mixture (12.5 mm Gradation). Gradation limits specified for 12.5 GPEM are used as design limits for development of PFC mix design for Florida Design. There are no mixture design guidelines currently available for the determination of trial gradations within the specification limit. Rather, the mixture designer has to use his own judgment to determine a trial gradation within the limits provided. Table 2-1. Gradation specifications according to GDT 114 (1996) Mixture Control Tolerance Asphalt Concrete 12.5 mm PEM Grading Requirements 0.0 3/4 in (19 mm) sieve 100 6.1 1/2 in (12.5 mm) sieve 80-100 5.6 3/8 in (9.5 mm) sieve 35-60 .7 No. 4 (4.75 mm) sieve 10-25 .6 No.8 (2.36 mm) sieve 5 10 .0 No. 200 (75 m) sieve 1-4 Design Requirement .4 Range for % AC 5.5-7.0 Class of stone (Section 800) "A" only Coating retention (GDT-56) 95 Drain-down, AASHTO T 305 (%) <0.3 B. APPARATUS

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8 The apparatus required shall consist of the following: 1. Drain-Down equipment as specified in GDT-127 (2005) or AASHTO T 305-97 (2001) 2. Marshall design equipment as specified in AASHTO T-245 3. Boil Test Equipment as specified in GDT-56 (2005) or ASTM D 3625 4. Balance, 5000 grams Capacity 0.1 grams accuracy. Step 2 Modified Marshall Design and Optimum AC After determining a trial aggregate blend the following steps are required to determine the asphalt content: 1. Heat the coarse aggregate to 350F 3.5F (176C 2.5 C ), heat the mould to 300F 3.5 F (148 C 2.5 C) and heat the AC to 330 F 3.5 F (165 C 2.5 C). 2. Mix aggregate with asphalt at three asphalt contents in 0.5 % interval nearest to the optimum asphalt content establishes in step 1. The three specimens should be compacted at the nearest 0.5% interval to the optimum and three specimens each at 0.5% above and below the mid interval. 3. After mixing, return to oven if necessary and when 320F 3.5F (160 C 2.5 C) compact using 25 blows on each side 4. When compacted, cool to the room temperature before removing from the mold 5. Bulk Specific Gravity: Determine the density of a regular shaped specimen of compacted mix from its dry mass (in grams) and its volume in cubic centimeters obtained from its dimensions for height and radius. Convert the density to the bulk specific gravity by dividing by 0.99707 g/cc, the density of water at 25C Bulk Sp.Gr = W / ( r2h/ 0.99707) = Weight (gms) 0.0048417/Height (in) W = Weight of specimen in grams R = radius in cm H = height in cm 6. Calculate percent air voids, VMA and voids filled with asphalt based on aggregate specific gravity 7. Plot VMA curve versus AC content 8. Select the optimum asphalt content at the lowest point on VMA curve

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9 Step 3 Drain-Down Test Perform the drain test in accordance with the GDT 127 (2005) (Method for determining Drain Down characteristics in Un-compacted Bituminous Mixtures) or AASHTO T 305-97 (2001). A mix with an optimum AC content as calculated above is placed in a wired basket having 6.4 mm (1/4 inch) mesh openings and heated 14C (25F) above the normal production temperature (typically around 350F) for one hour. The amount of cement, which drains from the basket, is measured. If the sample fails to meet the requirements of maximum drain down of 0.3%, increase the fiber content by 0.1% and repeat the test. Step 4 Boil Test Perform the boil test according to GDT 56 (2005) or ASTM D 3625 with complete batch of mix at optimum asphalt content as determined in step 2 above. If the sample treated with hydrated lime fails to maintain 95% coating, a sample shall be tested in which 0.5% liquid anti stripping additive has been used to treat the asphalt cement in addition to the treatment of aggregate with hydrated lime. 2.3 Overview of Evaluation of Preliminary OGFC/PFC Mix design Procedure Developed by Vardhan (2004) Varadhan (2004) introduced the Superpave gyratory compaction into PFC mixture design in lieu of the Marshall compaction used by Georgia DOT. The study used to make the specified changes in preliminary mix design approach and the development of long-term aging procedure for compacted PFC mixture are discussed in the following. 2.3.1 Determination of Compaction level for PFC The Georgia DOT prepares specimen using the Marshall Hammer with 25 blows on each side of the specimen. Due to the overall strong desire by both the FDOT and the

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10 University of Florida researchers to use a compaction procedure that is more in line with current mix design compaction procedures in America, it was decided to use the Superpave gyratory compactor for compacting the specimens. Based on the work performed by Varadhan (2004) it was determined that an appropriate compaction level of 50 gyrations was sufficient to compact OGFC mixtures. This determination was based on a modified locking point concept (Vavrik & Carpenter, 1998). The approach by Vavrik (1998) was developed for dense graded mixtures. Varadhan (2004) found that the use of the locking point concept by Vavrik & Carpenter (1998) resulted in a severe over compaction of OGFC mixtures, leading to aggregate breakdown. Therefore, the locking point concept was modified for use in OGFC mixtures, as described by Varadhan (2004). As determined by Vardhan (2004) the compaction curve for OGFC/PFC mixtures follows a logarithmic trend. To identify the locking point, the rate of change of slope of compaction curve was used. The stage, at which the rate of change of compaction was insignificant, is the point of maximum resistance to compaction. Thus, using the logarithmic regression of the compaction data, the rate of change of slope can be obtained as follows: y = m ln(x) + c Rate of compaction = dy/dx = m/x (at any x=N) Rate of change of slope of compaction curve = d2y/dx2 = -m/ x2 (at any x =N) Based on the above idea the locking point was identified as the point at which two gyrations at same gradient of slope were preceded by two gyrations at same gradient of slope. The gradient was taken up to four decimal places, as shown in Table 2-2 for FC-5 Granite (Varadhan, 2004). The reason this was chosen as locking point was based on the

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11 fact the change in air voids was insignificant at this stage and that this trend was consistently observed in all the mixtures. In addition, the compaction level as identified from visual observation was around 50-60. Thus, based on the above study, the locking points for theses mixtures were identified as shown in Table 2-3 Table 2-2. Locking Point Based on Gradient of Slope (Varadhan, 2004) FC-5 Granite # of Gyrations Gradient of slope 39 0.0018 40 0.0017 41 0.0016 42 0.0015 43 0.0014 44 0.0014 45 0.0013 46 (LP) 0.0013 47 0.0012 48 0.0012 49 0.0011 50 0.0011 Table 2-3. Locking Points of all Mixtures based on Gradient of Slope (Varadhan, 2004) Mixtures Locking Point FC-5 Limestone 56 FC-5 Granite 46 NOVACHIP 50 Thus based on above concept the locking points for FC-5 with Limestone, FC-5 with Granite and NOVACHIP were 56, 46 and 50 respectively. The specimens were compacted again to these gyrations and extraction of asphalt was performed to observe the gradations after compaction. For FC-5 Lime even when the gyrations were reduced to 56 from 125, the same amount of breakdown was observed. This clearly indicated that in case of limestone, the breakdown occurred in the initial stages itself i.e. at very low gyrations. Hence, even if

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12 the gyrations were to be further reduced, the breakdown was still going to persist. For FC-5 with granite and NOVACHIP, the gradation looks nearly the same as that of the original gradation. In addition, the air voids for FC-5 Granite and NOVACHIP were around 21 % and 15 % respectively, which is typical for these open graded mixtures. Thus, from the above the study it is clear that, though the locking point of each of these mixtures differed slightly from each other, it was around 50 gyrations. This was further corroborated by the study done by NCAT on the compaction levels of friction courses. NCAT suggests 50 gyrations as compaction level for all friction courses. Thus based on this study from visual observation and rate of change of compaction, NCAT study for friction course, Varadhan (2004) stated that 50 gyrations should be the compaction level for friction course mixes. 2.3.2 OGFC/PFC Mixture Design Procedure Proposed By Varadhan (2004) Use of modified asphalt cement does not require determination of surface capacity (Kc) as per GDT 114 Test method: B (1996). Boil test is not included in proposed mix design of PFC as a modified asphalt cement PG76-22 with 0.5% anti strip agent is used. The gradation band used by Varadhan (2004) with in GDT 114 (1996) specified gradation limits (Ref. Table 2-1) is shown in Figure 2-1. Following is the method developed and proposed: Modified GDT 114 test method: B by Varadhan (2004) 1. Heat the coarse aggregate, the mould to 350 F 3.5 F (176 C 2.5 C) and the AC to 330 F 3.5 F (165 C 2.5 C) 2. Mix aggregate with asphalt at three asphalt contents, viz., 5.5%, 6% and 6.5%. Just before mixing, add the required amount of mineral fibers to the aggregate. Prepare three samples at each of the asphalt content 3. After mixing, return to oven for two hours for STOA at 320 F 3.5 F (160 C 2.5 C). Then compact using the Superpave Gyratory Compactor 50 gyrations

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13 4. When compacted, cool to the room temperature before removing from the mold. It typically takes 1 hour 45 min to cool down. 5. Bulk Specific Gravity: Determine the density of a regular shaped specimen of compacted mix from its dry mass (in grams) and its volume in cubic centimeters obtained from its dimensions for height and radius. Convert the density to the bulk specific gravity by dividing by 0.99707 g/cc, the density of water at 25 C Gradation Band b y Vardhan (2004) 0102030405060708090100Sieve SizesPercentage Passing Max Control Points Min Control Points No. No. No. No. No. No. No. 3/8" 1/2" 3/4" 200 100 50 30 16 8 4 Figure 2-1. Gradation Band with in GDT 114 (1996) specified gradation limits used by Varadhan (2004) 6. Bulk Sp.Gr = W / ( r2h/ 0.99707) = Weight (gms) 0.0048417/Height (in) 7. W = Weight of specimen in grams 8. R = radius in cm 9. H= height in cm 10. Calculate percent air voids, VMA and voids filled with asphalt based on aggregate specific gravity 11. Plot VMA curve versus AC content 12. Select the optimum asphalt content at the lowest point on VMA curve

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14 Drain-Down Test Perform the drain test in accordance with the GDT 127 (2005) or AASHTO T 305-97 (2001). A mix with an optimum AC content as calculated above is placed in a wired basket having 6.4 mm (1/4 inch) mesh openings and heated 14 C (25 F) above the normal production temperature (typically around 350F) for one hour. The amount of cement, which drains from the basket, is measured. If the sample fails to meet the requirements of maximum drain down of 0.3 %, increase the fiber content by 0.1 % and repeat the test. It is recommended by GDOT that the asphalt content should not be below 6% because of coating issues. The film thickness requirement for granite mixture as per Georgia DOT is 27 microns. Moisture Damage Test Perform the moisture damage test in accordance with AASHTO T-283 (2003) on compacted specimen. The specimens are rolled in 1/8 wire mesh which are kept in position using two clamps on either edges of pills for avoiding fall down at high temperature of 60C (140F). 2.3.3 Long-Term Oven Aging Procedure Proposed for PFC Mixture by Varadhan (2004) In order to evaluate the mixture susceptibility to aging, it was necessary to develop a modified long-term aging procedure that was based on AASHTO PP2 (1994). Since these mixtures are very course and open, there is a possibility of these mixes falling apart during aging. Hence, a procedure was developed to contain the compacted pills from falling apart during aging. A 1/8 opening wire mesh is should be rolled around pills, with two clamps tightened at 1-inch distance from each end of the pill. The mesh size is chosen in

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15 order to ensure that there is good circulation of air within the sample for oxidation and at the same time, to prevent the smaller aggregate particles from falling off through the mesh. Specimens are kept in ovens with porous plate at bottom for 185 F 5.4 F (85 C 3 C) for 120 0.5 hours. After that time period, turn off the oven and open the door. Allow the oven and specimen to cool to room temperature for about 16 hours. 2.4 Verification of Florida Permeable Friction Course Mixture Design 2.4.1 Materials Aggregate and gradation selection An existing Georgia PEM gradation obtained from the Georgia DOT was used as a starting point in the mixture design. Figure 2-2 shows the gradation for the Georgia PEM. Interestingly, the Georgia DOT mixture design follows the middle of the specified gradation band on the coarse side, transitioning to the maximum allowable fines content on the fine side. This selection of gradation will likely result in a good coarse aggregate to aggregate contact structure, as well as ensuring the highest possible amount of asphalt binder in the mixture, without significant drain down. Two types of aggregate are used for this development i.e. Granite and Limestone. Nova Scotia granite and oolitic limestone from South Florida (White Rock) were used for preparing the mixtures. The same JMF is used for both granite and limestone mixture composed of aggregates from different stockpiles. The Job mix formula for the granite was composed of aggregates from stockpiles #7, #789 and Granite Screens. The job mix formula for the limestone was composed of aggregates from stockpiles S1A, S1B and limestone screens. Hydrated lime (1% by weight of aggregate) was used as anti-stripping agent for the granite aggregates. All aggregates were heated to 350F 3.5F (176 C 2.5 C) as specified in GDT 114

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16 Test Method: B Section C (1996). Table 2-4 and Table 2-5 shows composing of GPEM-limestone and GPEM-garanite job mix formula. Table 2-4. Composition of GPEM-Limestone gradation JMF Type S1A S1B Scrns JMF Control Points % Amount 55.56 37.37 7.07 100 Max Min Sieve Size Size^0.45 37.5 5.11 100 100 100 100 25 4.26 100 100 100 100 19 3.76 100 100 100 100 100 100 12.5 3.12 82 100 100 90 100 80 9.5 2.75 28 99 100 60 60 35 4.75 2.02 3 39 99 23 25 10 2.36 1.47 2 8 70 9 10 5 1.18 1.08 2 3 54 6 0.6 0.79 1 1 40 4 0.3 0.58 1 1 30 3 0.15 0.43 1 1 13 2 0.075 0.31 1 1 2 1 4 1 Table 2-5. Composition of GPEM-Granite gradation JMF Type #7 #789 Granite Granite Screens Lime JMF Control Points % Amount 55 37 7 1 100 Max Min Sieve Size Size^0.45 37.5 5.11 100 100 100 100 100 25 4.26 100 100 100 100 100 19 3.76 100 100 100 100 100 100 100 12.5 3.12 82 100 100 100 90 100 80 9.5 2.75 28 99 100 100 60 60 35 4.75 2.02 2 39 99 100 23 25 10 2.36 1.47 2 6 69 100 9 10 5 1.18 1.08 2 2 46 100 6 0.6 0.79 1 1 30 100 4 0.3 0.58 1 1 17 100 3 0.15 0.43 0 1 7 100 2 0.075 0.31 0 0 1 100 1 4 1 Binder and mineral fiber SBS modified PG 76-22 asphalt, with 0.5% anti strip agent was used in the mixture design. Mineral fiber (Fiberand Road Fibers) supplied by SLOSS Industries, Alabama,

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17 0.4% by weight of total mix, was added to mix in order to avoid binder drain drown. Chemical composition of the mineral fiber is Vitreous Calcium Magnesium Aluminum Silicates. Mineral fibers were shredded into fine fragments before adding to the mixture. Geor g ia's Permeable European Mixture Gradations for Limestone and Granite Mixes0102030405060708090100Sieve SizesPercentage Passing Georgia PEM Gradation Max Control Points Min Control Points No. No. No. No. No. No. No. 3/8" 1/2" 3/4" 200 100 50 30 16 8 4 Figure 2-2. Georgias Permeable European Mixture gradation band 2.4.2 Sample Preparation for Determination of Optimum Asphalt Content Based on experience, the Georgia DOT procedure almost always results in design asphalt content of 6 percent, when Georgia granite aggregates are used. However, following the GDOT GDT-114 (1996) procedure, three trial mixtures were prepared at different asphalt contents. The trial asphalt content of 5.5%, 6% and 6.5% were selected for the Nova Scotia granite blend for choosing the asphalt content that results in a minimum VMA. As per GDT 114 (1996), the specified range of percent asphalt content is 5.5%-7.0%. As a note, based on the early experience with the use of only three trial asphalt contents to obtain an optimal asphalt content, it was observed that it is necessary to use four trial asphalt contents for determining the optimum asphalt content. Choosing only

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18 three asphalt contents will always result in one of the chosen asphalt contents to show a minimum, whereas choosing four asphalt contents will result in a true minimum that can be verified. Figure 2-3 shows example of determination of higher asphalt content as optimum asphalt content due selection of (3) trial asphalt contents. V oids in Mineral Aggregates(VMA) Vs Asphalt Content (%AC)28.2028.4028.6028.8029.0029.2029.4029.605.05.56.06.57.07.5% ACVMA Higher optimum asphalt content with (3) trail asphalt Figure 2-3. Example of determination of inconsistent optimum asphalt content Because of this reason, a broader range of trial asphalt contents was used for the limestone mixture, namely 5.5%, 6.0%, 6.5% and 7%. For each trail asphalt content three pills were prepared. 2.4.4 Mixing and Compaction of Samples for Determination of Bulk Specific Gravity Sieved aggregates from each stockpile are batched by weight of 4400 grams for each pile. Three pills are prepared for each trial percentage. Hydrated lime 44 grams (1.0% of aggregate weight) is added to batched samples. Table 2-2 shows the amount of material used for mixing. Aggregates, tools, mixing drum, shredded fibers and the asphalt binder are heated to 330 F 3.5 F (165 C 2.5 C) for at least 3 hours. Aggregates are mixed with asphalt at all trial asphalt contents. Just before mixing, add the required

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19 amount of mineral fibers to the aggregate. Table 2-2 shows amount of aggregates and asphalt used for each trial blend. Once the sample is mixed it is placed in a clean metal tray. Due to the presence of the SBS in the asphalt binder, these mixtures tend to be sticky making the mixing somewhat challenging. In particular, it is important to ensure that there is no loss of fines while retrieving the mix from the mixing drum. The AASHTO RM 30 specification for loss of fines was used, requiring that a maximum 0.1 percent loss of fines. After mixing, mixtures are aged for short term of two hours at 320 F 3.5 F (160C 2.5 C) as per AASHTO PP2 (1994). The specimens are compacted to 50 gyrations using the Superpave Gyratory Compactor. Molds should be lubricated. The angle of gyration during compaction is 1.25 degrees. From prior experience, compacted samples should not be retrieved from molds immediately. They should be allowed to cool for 1hr 45 min before extracting the specimens from the molds. Once the specimen is ejected from the mold, it is allowed to cool for another 5 minutes at ambient room temperature before handling. It was found that if sufficient cooling of the specimen after extraction of the specimen from the mold were not followed (especially for granite mixtures), small aggregate particles would tend to dislodge and stick to gloves due to the high specimen air voids. Finally, it was found that it was necessary to allow the pills to cool at ambient room temperatures for another 24 hours before processing them any further.

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20 Table 2-6. Material quantities Bulk Specific Gravity Aggregate Weight = 4400 grams AC Content AC Weight (Grams) Fiber Weight (Grams) Total Weight 5.5 256.1 18.6 4674.7 6 280.9 18.7 4699.6 6.5 305.9 18.8 4724.7 7 331.2 18.9 4750.1 5.5 58.2 4.2 1062.4 6.0 63.8 4.3 1068.1 6.5 69.5 4.3 1073.8 7.0 75.3 4.3 1079.6 2.4.4 Determination of Optimum Asphalt Content The determination of bulk specific gravity test in accordance with AASHTO T166 (2000) cannot be conducted on the PFC mixtures because of their high air voids. The determination of Saturated Surface Dry (SSD) weight of the pills is not reliable for mixtures at these high air void contents as per Cooley et al (2002). Therefore, bulk specific gravity (Gmb) of pills was determined by Dimensional analysis, as described in GDOT-114 (1996). The determination of Theoretical Maximum Specific Gravity (Gmm) was made via the use of the Rice test procedure as per AASHTO T209 (2004). For preparation of samples for determination of Theoretical Maximum Specific Gravity as per AASHTO T-209-99 (2004), aggregates are batched by weight of 1100 grams. Two mixes for each trial asphalt percentage are prepared. Once all trial asphalt content pills had been prepared, the VMA was determined from the Theoretical Maximum Specific Gravity (Gmm) and the Bulk Specific Gravity (Gmb) determined from Dimensional analysis. The design asphalt content is selected at the point of minimum VMA. The main purpose of using minimum VMA criterion is to

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21 ensure reasonably high asphalt content of the mixture. Secondly, VMA is calculated on a volume basis and is therefore not affected significantly by the specific gravity of aggregate. Refer Appendix A for detail calculations and Laboratory work sheets of volumetric properties of PFC mixtures. Figure 2-4and Figure 2-5 show a summary of the volumetrics for the limestone and granite mixtures. Optimum asphalt contents of PFC mixtures were found to be 6.5% and 6.0% for the limestone and granite mixtures, respectively. The porous nature of limestone resulted in a higher optimum asphalt content.

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22 Effective Sp Grav. of Agg. % AC6 Gmm1 Gmb2 VMA3 (%) VTM4 (%) VFA5 (%) 2.513 5.5 2.323 1.877 29.40 19.21 34.67 6.0 2.314 1.908 28.62 17.54 38.71 6.5 2.298 1.927 28.30 16.16 42.89 7.0 2.286 1.934 28.42 15.39 45.84 Voids in total mix14.0015.0016.0017.0018.0019.0020.004.05.06.07.08.0% ACVTM (%) Voids in mineral aggregates28.0028.5029.0029.504.05.06.07.08.0% ACVMA (%) Voids filled with asphalt30.0032.0034.0036.0038.0040.0042.0044.0046.0048.004.05.06.07.08.0% ACVFA (%) Figure 2-4. Mix Design of OGFC with aggregate type: Limestone Optimum Asphalt Content: 6.5% VMA at Optimum Asphalt Content:28.30% Mineral Fiber: 0.4% of Total Mix Aggregate Type: Limestone Gmm1 = Maximum specific gravity of mixture, Gmb2 = Bulk specific gravity of mixture, VMA3 = Voids in Mineral Aggregates, VTM4 = Voids in Total Mix, VFA5 = Voids filled with Asphalt, AC6 = Asphalt Content

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23 Effective Sp Grav. of Agg. % AC6 Gmm1 Gmb2 VMA3 (%) VTM4 (%) VFA5 (%) 2.641 5.5 2.442 1.936 30.74 20.72 32.60 6 2.414 1.961 30.23 18.78 37.86 6.5 2.389 1.967 30.38 17.68 41.82 Voids in mineral aggregates30.1030.2030.3030.4030.5030.6030.7030.8055.566.57% ACVMA (%) Voids filled with Asphalt30.0032.0034.0036.0038.0040.0042.0044.0055.566.57% ACVMA (%) Voids in Total Mix17.0018.0019.0020.0021.0055.566.57% ACVTM (%) Figure 2-5. Mix Design of OGFC with aggregate type: Granite Optimum Asphalt Content: 6.0% VMA at Optimum Asphalt Content:30.23% Mineral Fiber: 0.4% of Total Mix Aggregate Type: Limestone Gmm1 = Maximum specific gravity of mixture, Gmb2 = Bulk specific gravity of mixture, VMA3 = Voids in Mineral Aggregates, VTM4 = Voids in Total Mix, VFA5 = Voids filled with Asphalt, AC6 = Asphalt Content

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24 2.5 Evaluation of Film Thickness Criterion in PFC Design The Georgia DOT uses a required minimum calculated asphalt film thickness criterion for ensuring that the mixture has enough asphalt for adequate durability. Since durability of mixtures is a surface phenomenon, where the binder is damaged from the surface inward, a mixture with a low film thickness is expected to damage more than a mixture with a thicker film, irrespective of surface area. Therefore, it is important to clearly establish a link between the calculated film thickness and the physics of the mixture in question. The appropriate film thickness calculation is affected by the aggregate structure of the mix. The first attempts to calculate minimum asphalt film thicknesses were made by Goode and Lufsey (1965). Their method was based on empirical considerations, leading to the development of the theoretical film thickness (Hveem, NCAT 1991), which assumes that all aggregates are rounded spheres, with predefined surface areas, which are coated with an even thickness of asphalt film. Recognizing that these theoretical film thickness calculations were developed primarily for fine-graded mixtures with very different aggregate structures from that found in coarse-graded mixtures, let alone OGFC and PFC mixtures, Nukunya et al. (2001) developed an effective film thickness concept based on a physical model of coarse-graded mixtures. Nukunya, et al. (2001) observed that the aggregate structure for fineand coarse-graded mixtures is fundamentally different, as shown in Figure 2-6 Fine-graded mixtures tend to have more continuous grading such that the fine-aggregates are an integral part of the stone matrix. Coarse mixtures, on the other hand, tend to have aggregate structures that are dominated by the coarse aggregate portion (i.e., stone-to-stone contact).

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25 COARSE FINE Figure 2-6. Aggregate Structure for Coarse and Fine Mixtures (Nukunya et al. [2001]) Therefore, coarse-graded PFC mixtures are effectively composed of two components: the first one is the interconnected coarse aggregate, and the second component is the fine mixture embedded in between the coarse aggregate particles. The mixture made up of asphalt and fine aggregates coats the coarse aggregate particles, and the fine aggregates within that matrix have access to all the asphalt within the mixture. This results in film thicknes that is much greater than that calculated using conventional theoretical film thickness calculation procedures that assume that the asphalt is uniformly distributed over all aggregate particles. To account for the different nature of the aggregate structure in coarse-graded mixtures, a modified film thickness calculation, entitled the effective film thickness, was developed by Nukunya, et al. (2001), in which the asphalt binder is distributed onto the portion of the aggregate structure that is within the mastic. Also recognizing that the Theoretical Film Thickness (Hveem, NCAT 1991) may not adequately represent the physics of PFC mixtures, the Georgia DOT introduced a modified film thickness calculation. However, the Georgia DOT modified film thickness calculation method is based on empirical considerations and yields similar results to the theoretical film thickness calculations.

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26 More recently, work at the University of Florida under the direction of Drs. Roque and Birgisson has led to the establishment of a tentative gradation selection framework for the optimization of the fracture and rutting resistance of dense graded mixtures. Key concepts in this new proposed framework include the observation that enhanced cracking and rutting resistance can be obtained by ensuring that the aggregates in the course portion of the mixture gradation interact sufficiently amongst each other to allow for the effective transfer of forces through the course-aggregate portion of the mixture. This interaction of the course aggregate component should not reach down to the finer materials, so as to control mixture sensitivity. For optimizing the fracture resistance of mixtures, the material within the interstitial volume of the course aggregate portion also needs to be proportioned and designed so that an adequate Dissipated Creep Strain Energy (DCSE) limit is maintained, as well as providing enough flow and ductility to enhance the fracture resistance of the mixture. Too little interstitial material, or interstitial material with a low creep strain rate, will result in a brittle mixture. It is anticipated that these gradation concepts will be transferable to OGFC and PFC mixtures, thus allowing for the development of guidelines for the selection of gradations that optimize the resistance to cracking and rutting. Using these concepts it is also possible to define a modified film thickness that is calculated strictly based on the interstitial volume component of the mixture. In the following the Georgia DOT modified film thickness criterion will be compared to the effective film thickness criterion developed by Nukunya, et al. (9), as well as the new film thickness criterion based on interstitial volume considerations. For completeness the Theoretical Film Thickness proposed by (Hveem, NCAT 1991) is

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27 also calculated and included in the comparison, even though it is recognized that it may not adequately represent the structure of PFC mixtures. However, first the methods for calculating these asphalt film thicknesses are reviewed. 2.5.1 Review of Asphalt Film Thickness Calculation Methods Goode and Lufseys method Even though this method is not used in this research, it is important to note the contributions of Goode and Lufsey (1965), who related empirically asphalt hardening to voids, permeability and film thickness. They recognized that the hardening of the asphalt binder in a mix was a function of air voids, film thickness, temperature, and time. Goode and Lufsey (1965) introduced the concept of the ratio of the air voids to bitumen index, as a measure of the aging susceptibility of a mix (developed for dense graded mixture with 4% air voids). Goode and Lufsey (1965) had proposed a maximum value of 4.0 for this ratio, which they believed, would prevent pavement distress by reducing the aging of the asphalt film coating the aggregate. Mathematically, what they stated was: 410(%)3exBitumenIndAirVoids (Maximum) (2.1) Where: Film thickness (microns) = Bitumen index x 4870 Equation 2-1 with the air voids content of the mixture is reduced to a minimum film thickness requirement based on air voids to bitumen index ratio analysis. The film thickness then varies with the percent air voids as follows (Goode and Lufsey, 1965):

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28 31044870(%) AirVoidsessFilmThickn (Minimum) (2.2) The total air voids in the compacted PFC limestone mixtures at 50 gyrations is 16.16%. Goode and Lufseys minimum film thickness requirement for 16.16% is 19.67 microns. Theoretical film thickness method This technique for calculating film thickness is based on the surface area calculated as per Hveem (1991). The surface area factors suggested by Hveem (1991) is shown in Table 2-7. The Film thickness of asphalt aggregates is a function of the diameter of particles and the effective asphalt content. The film thickness is directly proportional to volume of the effective asphalt content and inversely proportional to diameter of particle: aggefffilmWSAVT1000 (2.3) filmT = Film Thickness SA = Surface Area aggW = Weight of aggregate Table 2-7. Surface Area Factor Hveem (1991) Sieve Size Surface Area Factor Percentage Passing Maximum Sieve Size 2 Percent Passing No. 4 2 Percent Passing No. 8 4 Percent Passing No. 16 8 Percent Passing No. 30 14 Percent Passing No. 50 30 Percent Passing No. 100 60 Percent Passing No. 200 160

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29 Effective film thickness method (Nukunya et al, 2001) According to this method only aggregates passing the No. 8 Sieve are taken into account in the calculation of the surface area by using factors suggested by Hveem (1991) Then Equation 2-3 is used for calculating Film Thickness. Table 2-8. Surface area Factor suggested by Nukunya (2001) for coarse aggregate structure Sieve Size Surface Area Factor Percent Passing No. 8 4 Percent Passing No. 16 8 Percent Passing No. 30 14 Percent Passing No. 50 30 Percent Passing No. 100 60 Percent Passing No. 200 160 Modified film thickness method used by gdot Georgia developed this method primarily for PEM mix with granite aggregate. The basic assumption was that the absorption of asphalt is very low or no absorption by surface pores of granite aggregate. The method is empirical and assumes that fixed aggregate unit weight per pound of aggregate, based on Georgia aggregates. Hence, the effective film thickness () is given as: effT AC of gr. Sp. ft. sq.per m 0.09290Sq. lbft / squarein area Surface] Poundsper g 453.6 [ ] Aggregate %by divided Poundsper g 453.6 [effT (2.4) Where, = Effective Film Thickness effT Film thickness based on interstitial volume concept The aggregate interaction curve is plotted to determine the portion of the gradation curve with interacting aggregate sizes. Following is equation used for calculating points of interaction :

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30 )Re(%Re(%100*)Re(%intRe%SizeSieveattainedSizeSieveSuccesiveattainedSizeSieveattainedPonInteractioParticletained (2.5) The aggregates are considered to be interacting, if the percent-retained particle interaction is between 30% and 70%. Any point that falls outside these limits is considered to be non-interacting. Therefore, aggregate sizes below this break point are not interacting towards contribution of strength. These aggregate sizes are filling the cavities between the coarse aggregate structure defined by aggregate sizes above the break point. The aggregate sizes below the break point along with asphalt are contributing to Interstitial Volume. Mastic, comprising aggregate sizes below the break point, asphalt, and air voids, form the interstitial volume of the compacted mixture. Hence, the interstitial volume is the ratio of mastic in specimen to the total volume of the compacted mixture, as shown in Equation 2-6: MixtureCompactedofVolumeTotalMasticofVolumeVolumealInterstiti____)__(_ (2.6) In order to calculate the film thickness of the particles in the interstitial volume, the surface area of the particles in the interstitial volume needs to be determined. As per the hypothesis discussed above, aggregates below the break point are within the interstitial volume. Hence, the surface area (SA) of aggregates below break point can be obtained from the surface area factors given in Table 2-9. As the absorption in granite is negligible, the as the effective asphalt content (V) is taken to be the total asphalt content of the compacted mixture. Weight of aggregates (W) in air is taken into account for calculating film thickness. Equation 2-7 denotes calculation of film thickness with in interstitial volume: eff agg

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31 aggefffilmWSAVT1000 (2.7) Recognizing that these film thickness calculations all use effective asphalt content to determine the available amount of asphalt binder for the coating of particles, it is important to establish clear guidelines for determining the effective asphalt content of PFC mixtures. Table 2-9. Surface area factors for Interstitial Volume Sieve Size Surface Area Factor Percentage Passing Maximum Sieve Size 2 Percent Passing No. 4 2 Percent Passing No. 8 4 Percent Passing No. 16 8 Percent Passing No. 30 14 Percent Passing No. 50 30 Percent Passing No. 100 60 Percent Passing No. 200 160 Aggregate with in interstitial volume Aggregate with in interstitial volume The Georgia DOT method of film thickness calculations assumes that there is no absorption of asphalt into the aggregate surfaces. Their method of film thickness calculation is an empirical approach. This assumption may be a reasonable approximation for low absorption granite aggregates. However, for high absorption limestone aggregates it is necessary to account for absorption. In this research, asphalt absorption was estimated using two approaches: 1) Asphalt absorption obtained from basic volumetric equations is used to calculate effective asphalt content. This is the true asphalt contributing towards in film thickness: 13. Effective Specific gravity (Gsb): The effective specific gravity is calculated from the maximum specific gravity (Gmm) of mixture and Asphalt content (). Pb

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32 GbPbGmmPbGse10011001 (2.8) 14. Asphalt Absorption (): The absorbed asphalt content is differences of bulk volume of aggregate and the effective volume. asbP GbGsbGseGsbGsePasb100 (2.9) 15. Effective Volume of Asphalt (): The effective volume of asphalt is amount of asphalt available for coating aggregates, which is obtained by subtracting absorbed asphalt from Total Asphalt Content (). effV TotalP asbTotaleffPPV (2.9) 2) Determination of effective asphalt content based on bulk specific gravity determined through from the CoreLok test procedure as per CoreLok manual (2003). The main justification for using the CoreLok procedure is that open graded mixes readily absorb water and drain quickly when removed from the water tank, during the determination of Saturated Surface Dry (SSD). Weight conditions in traditional laboratory-based procedures for determining. The lack of control over the penetration and drainage of water in and out of asphalt specimens creates a problem with the water displacement measurement using the current principles for determination of specific gravity as per Cooley et all (2002). The CoreLok system makes the determination of SSD conditions unnecessary. Perform calculation as per directions given in Data Collection Table: 2.10

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33 Table 2-10. CoreLok calculation Sheet A B C D E F G H I J Sam-ple I D Bag Weight(g) Dry Sample Weight before Sealing (g) Sealed Sample Weight in Water (g) Dry Sample Weight After Water Submersion(g) RatioB/A Bag Volume CorrectionFrom Table Total Volume(A + D) C Volumeof Sample A/F Volumeof Sample (G-H) Bulk Specific Gravity B/I I II After determination of Bulk Specific gravity (Gmb) following steps in calculation are involved for estimating the effective asphalt content. Air Voids in compacted mix (VTM) and Voids in Mineral Aggregates (VMA) are calculated using Equation 2-10 and Equation 2-12 based on bulk specific gravity determine by CoreLok method. 1001GmmGmbVTM (2.10) 100100GmbWGsbWVMATagg (2.11) TTVVaggVVTMVeff100. (2.12) Where, TV = Total volume of compacted specimen Vagg = Volume of aggregate Gmm = Maximum theoretical specific gravity. Gsb = Aggregate bulk specific gravity

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34 VTM = Voids in total mix VMA = Voids in Mineral aggregate. TW = Weight of Total specimen aggW = Weight of aggregate 2.5.2 Comparison of Results Obtained from Each Film Thickness Calculation Method Limestone has higher absorption capacity than granite aggregate. Figure 2-7 shows the absorption of asphalt into the surface cavities of limestone aggregate, therefore reducing the effective asphalt content and resulting in a lower film thickness when compared to granite mixtures. (a) (b) Figure 2-7. (a) Granite with high film (Required against stripping) (b) Limestone with low film thickness as compared with granite due to absorption The four different asphalt film thickness calculations methods discussed previously were used to calculate the film thickness of asphalt with in compacted granite and limestone PFC mixtures. The surface area calculated by the Nukunya et al (2001) Method and the Interstitial Volume method is exactly same for the two mixtures evaluated, due to the fact that the break point defining the interstitial volume is at the No. 8 Sieve Size.

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35 Table 2-11. Comparison of Film Thickness method for Limestone mixture Method Film Thickness (microns) Asphalt absorption Film Thickness (microns) Corelok Method Theoretical Film Thickness (Hveem 1991) 34.20 31.22 Nukunya's Effective Film thickness 50.71 46.29 GDOT 34.80 31.58 Interstitial Volume 50.71 46.29 Table 2-11 shows the comparison of true film thickness to film thickness calculated from CoreLok bulk specific gravity. CoreLok is determining comparative film thickness. Nukunyas method and Interstitial volume method are predicting higher film due consideration of coarse aggregate structure. Table 2-12. Comparison of Film Thickness method for Granite mixture Method Film Thickness (microns) Asphalt Absorption Theoretical Film Thickness (Hveem 1991) 37.25 Nukunya's Effective Film thickness 55.23 GDOT 38.10 Interstitial Volume 55.23 As shown in Table 2-12, Comparison of Film Thickness method for Granite mixture, GDOT method is over predicting film thickness. Hence, in summary, either the CoreLok or the equivalent water absorption methods can be used. However, the Corelok method is still under review and development, nationally. Therefore, until the method has been thoroughly verified on the national level, it is recommended that the equivalent

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36 water absorption method be used as a lower limit on asphalt absorption. Similarly, the asphalt film thickness of the aggregates within the interstitial volume is the most theoretically correct method. However, it is still under development and evaluation. Therefore, it is recommended that the Effective Film Thickness calculation proposed by Nukunya, et al. (2001) be used to determine the film thickness of PFC mixtures. 2.5.3 Relative Minimum Film Thickness Requirement For establishing minimum film thickness requirement based on Effective Film Thickness Nukunya et all (9), Georgia Department of Transportation minimum film thickness criterion is used as standard. According to GDOT minimum film thickness required for granite PFC mixture against stripping is 27 microns for surface area calculated based on GDOT factors. This requirement is not specified in their specification but they use it as tentative film thickness criterion. Georgia DOT typically uses granite aggregate for their GPEM mixtures. Georgia DOT, ignore asphalt absorption while calculating film thickness as per Eason (2004). But limestone due to its porous surface texture has high asphalt absorption capacity. This property of limestone does not allow attainment of high film thickness. Aggregates with different asphalt absorption will lead different minimum film thickness. Therefore, the relative minimum film thickness requirement is calculated for set of range of asphalt absorption, i.e. 0-0.5%, 0.5-1 %, 1 % or more. While calculating minimum film thickness requirement for each of these ranges, upper limit of range is considered. For calculating the relative minimum film thickness requirement, 27 micron is used to back calculate the effective asphalt content. )(GDOTVeff

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37 As Georgia DOT ignores asphalt absorption this effective asphalt content is total asphalt content of the mixture. Subtracting upper limit of range of asphalt absorption () from this the total asphalt content gives actual effective asphalt content (). This value of effective asphalt content is substituted in standard film thickness Equation 2-3 using surface area as per Nukunya et al (2001) as shown in Step V for calculating relative minimum film thickness (). absorptionAsphalt NukunyaVeff MinimumlativeT_Re Optimum gradation band for surface area calculation A gradation band, which is representative of all gradations with in specified control limits, is required for calculating surface area for relative minimum film thickness requirement. Average of maximum control points and minimum control points of specified gradation limits as per GDT-114 (1996) to obtain optimum gradation, which represents gradation between those gradation limits. Figure 2-8 shows optimum gradation band used for calculating surface area. Job mix formula of this optimum gradation showed in Table 2-13 is used to calculate surface area as per Georgia DOT method () and Nukunya et al. (2001) (). It is assumed that this optimum gradation represents the different gradation band with in this specified limit. Therefore the film thickness calculated for this optimum gradation band represents al set of gradation band with in this gradation limit. GDOTaSurfaceAre )2001(NukunyaaSurfaceAre

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38 Optimum Gradation Band for Minimum Film thickness requirement Calculation 0204060801000.000.501.001.502.002.503.003.504.00Sieve Size^0.45Percentage Passing (%) Max Control points Min Control Points O p timum Re p resentative Gradation Figure 2-8. Optimum Gradation Band for Calculating Minimum film thickness requirement Table 2-13. JMF of Optimum gradation for Gradation limits as per GDT 114 (1996) Type % Amount Sieve Size Size^0.45 Optimum Gradation Band 37.5 5.11 100 25 4.26 100 19 3.76 100 12.5 3.12 90 9.5 2.75 48 4.75 2.02 18 2.36 1.47 8 1.18 1.08 5 0.6 0.79 4 0.3 0.58 3 0.15 0.43 2 0.075 0.31 2 Following steps are used for calculating relative film thickness requirement: Step I: micronsTimumGDOT27min Step II: 1000minaggregateGDOTimumGDOTGDOTWaSurfaceAreTVeff

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39 Step III: GDOTasphaltVeffTotal Step IV: absorptionasphaltNukunyaAsphaltTotalVeff Step V: aggregateNukunyaNukunyaMinimumlativeWaSurfaceAreVeffT )2001(_Re1000 Based on above steps minimum film thickness requirement is calculated for different set of asphalt absorption. The relative minimum film thickness for Nukunya et al (2001) based on this concept is tabulated in Table 2-14. Table 2-14. Minimum film thickness requirements for different set of Asphalt absorption Asphalt absorption Range Total asphalt content (ml) Maximum asphalt absorption (%) Effective asphalt content (ml) Minimum film thickness requirement (microns) 0 % to 0.5% 213.84 0.5% 191.84 32 0.5% + to 1 % 213.84 1% 169.84 28 1%+ to 1.5% 213.84 1.50% 147.84 24 1.5% or more 214.84 Greater than 1.5 % 125.84 13 2.6 Recommended Specification for PFC Mixture Design SCOPE The method of design for a modified open graded bituminous mixture consists of four steps. The first step is the selection of a trial aggregate blend and asphalt binder. The second step involves the determination of optimum asphalt content and checking for adequate asphalt film thickness to ensure durability. The third step involves the performance of AASHTO T 305-97 (2001) (i.e. a asphalt drain down test), and the fourth step involves the performance of AASTHO T-283 (2001). The details of each step are discussed below.

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40 APPARATUS The apparatus required shall consist of the following: 1. Drain-Down equipment as specified in AASHTO T 305-97 (2001). 2. Superpave gyratory compactor. 3. Equipment to perform AASHTO T-84 and T-85. 4. Balance, 5000 gr. Capacity, 0.1 gr. Accuracy. 5. 10 metal pie pans 6. Oven capable of maintaining 330 F 3.5 F (165 C 2.5 C) 7. Oven capable of maintaining 350 F 3.5 F (176 C 2.5 C 8. Timer. STEP 1: Determination of Trial Blend and Asphalt Binder The aggregate trial blend should be selected to fit within the gradation limits listed in Table 2-15 and shown in Figure 2-9. The asphalt binder should be SBS modified PG 76-22 asphalt. Either the addition of 0.5% liquid anti-strip agent or 1 percent hydrated lime is required. The use of hydrated lime requires pretreatment of the aggregates with the hydrated lime. 0.4 % mineral fiber by weight of total mix should be added to avoid binder drain down. Table 2-15. Proposed Gradation and Design specifications for Florida Permeable Mixture Control Tolerance Asphalt Concrete 12.5 mm PFC Gradation Requirement 0.0 3/4 in (19 mm) sieve 100 6.1 1/2 in (12.5 mm) sieve 80-100 5.6 3/8 in (9.5 mm) sieve 35-60 .7 No. 4 (4.75 mm) sieve 10-25 .6 No.8 (2.36 mm) sieve 5 10 .0 No. 200 (75 m) sieve 1-4 Design Requirements .4 Range for % AC 5.5-7.0 AASHTO T-283 (TSR) 80 Drain-down, AASHTO T 305 (%) <0.3

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41 Gradation Band b y Vardhan (2004) 0102030405060708090100Sieve SizesPercentage Passing Max Control Points Min Control Points No. No. No. No. No. No. No. 3/8" 1/2" 3/4" 200 100 50 30 16 8 4 Figure 2-9. Proposed Gradation limits for Florida Permeable Friction Course Mixtures STEP 2: Determination of Optimum Asphalt Content and Asphalt Film Thickness Heat the coarse aggregate, the mould to 350F 3.5F (176C 2.5 C) and the AC to 330 F 3.5 F (165 C 2.5 C) Mix aggregate with asphalt to obtain at least four trial asphalt contents, viz., 5.5%, 6%, 6.5% and 7%. Just before mixing, add the required amount of mineral fibers to the aggregate. Prepare three samples at each of the asphalt contents After mixing, return the mix to oven for two hours for STOA at 320 F 3.5 F (160 C 2.5 C). Then compact to 50 gyrations using the Superpave Gyratory Compactor When compacted, cool down at room temperature for 1 hour 45 minutes before removing the specimens from the compaction mold. Determine Bulk Specific Gravity: Determine the density of a regular shaped specimen of compacted mix from its dry mass (in grams) and its volume in cubic centimeters obtained from its dimensions for height and radius. Convert the density to the bulk specific gravity by dividing by 0.99707 g/cc, the density of water at 25 C Bulk Sp.Gr = W / ( r2h/ 0.99707) = Weight (gms) 0.0048417/Height (in) W = Weight of specimen in grams R = radius in cm

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42 H = height in cm Determine Theoretical Maximum Specific Gravity according to AASHTO T-209-99 (2004). Calculate percent air voids, VMA and voids filled with asphalt based on aggregate specific gravity Plot VMA curve versus AC content and determine point of minimum VMA, select corresponding AC as Optimum asphalt content. Prepare a mixture at the optimal asphalt content. Determination of film thickness: Step (I) Determination of Effective Specific gravity (): asbP GbPbGmmPbGse10011001 (2.13) Step (II) Determination of Asphalt absorption (): asbP GbGsbGseGsbGsePasb100 (2.14) absWater Determined is in percentage of weight of aggregate. Convert into volume of water in ml, by using following equation:03.1*100)(__*_gramsaggregateofWeightPPabsmlabsabs (2.15) Step (III) Determination of Effective Volume of Asphalt (): effV mlabsabsTotaleffPPV_ (2.16) (Where = Total asphalt content in ml) TotalP Calculate the Effective Film thickness using following procedure as per Nukunya et al (2001): a) Determine Surface area (SA) from Table 2 below:

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43 Table 2-16. Surface area factor as per Nukunya et al (2001) Sieve Size Surface Area Factor Percent Passing No. 8 4 Percent Passing No. 16 8 Percent Passing No. 30 14 Percent Passing No. 50 30 Percent Passing No. 100 60 Percent Passing No. 200 160 b) Film thickness of asphalt (in microns): aggefffilmWSAVT1000 (2.17) where, aggW = Weight of aggregate SA = Surface area The minimum acceptable effective film thickness is determined as a function of the measured percent asphalt absorption per weight of aggregate as follows: Table 2-17. Minimum Effective Film Thickness Requirements Percent Asphalt Absorption Minimum Required Film Thickness (micron) 0.5 % or less 32 0.5+ to 1 % 28 1.0+ to 1.5 % 24 Greater than 1.5 % 13 E Step 3: Performance of Drain-Down Test Perform the drain test in accordance with the AASHTO T 305-97 (2001). A mix with an optimum AC content as calculated above is placed in a wired basket having 6.4 mm (1/4 inch) mesh openings and heated 14 C (25 F) above the normal production temperature (typically around 350F) for one hour. The amount of cement, which drains

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44 from the basket, is measured. If the sample fails to meet the requirements of maximum drain down of 0.3 %, increase the fiber content by 0.1 % and repeat the test. Step 4: Performance of Moisture Damage Test Perform the moisture damage test in accordance with AASHTO T-283 (2003) on compacted specimen. The specimens are rolled in 1/8 wire mesh which are kept in position using two clamps on either edge of the pill for avoiding mixture damage or breakdown at the conditioning temperature of 60C (140F). Minimum requirements should include TSR of 0.8 or greater. 2.7 Conclusion of Verification of PFC mixture Design Procedure The research presented in this chapter led to the following conclusions: It is recommended that at least (4) trial asphalt content should be used for predicting fairly accurate optimum asphalt content. Only PG 76-22 SBS modified binder containing 0.5% liquid anti stripping agent should be used. Minimum amount of batched sample for sample should not be less than 1000 grams for all purposes of testing. Air voids levels in the PFC limestone mixture were around 16% at 50 gyrations. Gradation analysis by Varadhan (2004) on extracted aggregate after compaction showed that the limestone undergoes crushing early in the compaction process. Therefore, the specified gradation limits may have to be adjusted for limestone to obtain air voids in the desired 18-22 percent range. In order to ensure adequate durability, the effective film thickness method developed by Nukunya, et al. (2004) should be used. In order to determine the effective asphalt content, the aggregate asphalt absorption should be used.

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CHAPTER 3 EVALUATION OF I-295 PFC MIX DESIGN PFC pavements are subjected to high temperature variance, hydroplaning and are in direct contact with rolling loads. In order to check field performance of PFC in Florida, construction of a test section was proposed at I-295, Jacksonville, FL. The Mix design of for this section follows the procedure discussed in Chapter 2. 3.1 Objective The objective of this study is to evaluate mix design procedure of PFC mixture at I-295 test section. The I-295 test section will be monitored for its long-term performance. Gradation selections for optimizing fracture resistance. Determination of optimum asphalt content for attaining minimum voids in the mineral aggregate (VMA) for ensuring high binder coating without drain down. Obtain a mixture for I-295 with highest Energy Ratio among selected gradation to ensure best performance. 3.2 Scope of Project Separate mix design was carried on gradation proposed by DOT contractor (Gradation (1)) and designed gradation (Gradation (2) to determine optimum asphalt content. Following is the complete plan of project:For each of the gradations, 4-trial asphalt percentages are used to obtain a VMA curve. The reason for selecting 4-trial percentages is to obtain polynomial curve for determining point of minimum VMA. Sieving, batching, mixing and compaction, as discussed in section 3.3.1 of this chapter, of mixes is done as specified in previous development in laboratory. Asphalt used is SBS modified PG76-22, which contains 0.5% 45

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46 anti strip agent in addition to 1% of hydrated lime added to aggregates to resist against stripping. Dosage rate of mineral fiber is 0.4% by total weight of mix. Superpave Indirect tensile test is run on compacted mixes for both gradations, in order to obtain fracture test parameters including energy ratio. Process of testing and criteria considered are discussed in section 3.4 of this chapter. Selection of gradation based on higher energy ratio for I-295 test section. Effect of moisture conditioning and long-term oven aging on selected gradation. 3.3 Materials used for I-295 PFC project 3.3.1 Aggregate and Hydrated Lime The final aggregate blend for Gradation (1) and Gradation (2) is composed of #67 Granite stone from Pit No TM-579/NS-315, #78 Granite Stone from Pit No GA-383 and Granite Screens from Pit No. TM-579/NS-315. The FDOT codes for these source stone stockpiles, #67 Granite is 54, #78 Granite is , and for Granite Screens is respectively. The producer of these aggregates is Martin Marietta Aggregate. Figure 3-1 shows the gradation band used for I-295 PFC project and control points as per FDOT specification SECTION 337. Table 3-1 and Table 3-2 gives details of composing of job mix formula of Gradation (1) and Gradation (2) respectively. One percent by weight of aggregate hydrated lime is added to the mixture as an antistrip agent. Global Stone Corporation provided hydrated lime. 3.3.2 Binder and Mineral Fiber An SBS polymer modified asphalt cement PG 76-22 with 0.5% antistrip agent was used in this project. Mineral fiber used was regular FIBERAND ROAD FIBERS. Atlantic Coast Asphalt Co. supplied asphalt and mineral fiber. The dosage rate of mineral fiber was 0.4% by weight of total mix.

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47 I-295 PFC Gradations0.010.020.030.040.050.060.070.080.090.0100.0Sieve SizesPercentage Passing Gradation (1) DOT Max Control Points Min Control Points Gradation (2) UF No. No. No. No. No. No. No. 3/8" 1/2" 3/4" 200 100 50 30 16 8 4 Figure 3-1. Gradation of I-295 PFC mixtures Table 3-1. JMF composition of Gradation (1) Type #67 Granite #78 Granite Granite Screens Lime JMF Control Points % Amount 20 70 9 1 100 Max Min Sieve Size Size^0.45 37.5 5.11 100 100 100 100 100 25 4.26 100 100 100 100 100 19 3.76 100 100 100 100 100 100 100 12.5 3.12 60 95 100 100 89 95 85 9.5 2.75 45 62 100 100 62 65 55 4.75 2.02 8 6 91 100 15 25 15 2.36 1.47 4 4 61 100 10 10 5 1.18 1.08 3 3 38 100 7 0.6 0.79 2 3 22 100 5 0.3 0.58 2 3 15 100 5 0.15 0.43 2 2 7 100 3 0.075 0.31 1 1 3.5 100 2 4 1 Table 3-2. JMF composition of Gradation (2) Type #67 Granite #78 Granite Granite Screens Lime JMF Control Points % Amount 30.0 60.3 8.8 1 100 Max Min Sieve Size Size^0.45 37.5 5.11 100 100 100 100 100 25 4.26 100 100 100 100 100

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48 Table 3-2. Continued Type #67 Granite #78 Granite Granite Screens Lime JMF Control Points % Amount 30.0 60.3 8.8 1 100 Max Min 19 3.76 100 100 100 100 100 100 100 12.5 3.12 60 95 100 100 85 95 85 9.5 2.75 45 62 100 100 61 65 55 4.75 2.02 8 6 91 100 15 25 15 2.36 1.47 4 4 61 100 10 10 5 1.18 1.08 3 3 38 100 7 0.6 0.79 2 3 22 100 5 0.3 0.58 2 3 15 100 5 0.15 0.43 2 2 7 100 3 0.075 0.31 1 1 3.5 100 2 4 1 3.4 Location of Project Figure 3-2 shows the project location, which is on I-295 between Lem Turner Road and Duval Road in Jacksonville, Florida. The test section starts at MP 31.910 (Station 1684+88.86 on I-295) and ends at MP 32.839 (Station 1733+91.61 on I-295), outside lane at northbound and south bound. Figure 3-2. Project Location

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49 3.5 Specification and Hypothesis Used As per FDOT specification SECTION 337-4, developed based on previous work done described in Chapter 2, and the design of the PFC mixtures is based on the final procedure developed in Chapter 3. The basic steps in the mixture design may be summarized as follows: 1. The design number of gyration should be 50. 2. Final JMF should be within the gradation limit specified in Table 337-2 of FDOT specification SECTION 337-3.3.2. This specified gradation limit is shown in Table 3-3 3. The PFC mix design should use a SBS modified PG 76-22 asphalt binder. 4. The optimum asphalt content should be selected at the minimum voids in the mineral aggregate (VMA) content. 5. The air void content should be between 18 and 22 percent. 6. Hydrated Lime dosage rate of 1.0% by weight of the total dry aggregate. 7. Mineral fiber dosage rate of 0.4% by weight of the total mix. Table 3-3. PFC Gradation Design Range from FDOT specification SECTION 337 Control Points Max Min Sive Size (mm) % Amount Passing 37.5 25 19 100 100 12.5 95 85 9.5 65 55 4.75 25 15 2.36 10 5 1.18 0.6 0.3 0.15 0.075 4 1

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50 The FDOT contractor proposed a JMF (Gradation (1)) for the given source gradations of stockpiles. As the source gradation was gap graded and gradation limits according to SECTION 337 are tight, it was difficult to adjust this gradation to obtain another candidate gradation. Therefore, only one other trial gradation was used in addition to the contractors gradation. The second gradation, denoted as Gradation (2) was based on increasing the amount of coarser stone in the mix. This objective was accomplished by increasing the percentage of # 67 granite from 20 % to 30 %. Even though, the material type used in Georgia PEM mix design development is different than in the I-295 PFC project, its characteristics are used as base for the evaluation of fracture results. Table 3-1 and Table 3-2 shows source gradation and final JMF of Gradation (1), Gradation (2) and Georgia PEM gradation. The hump in gradation at No. 4 sieve might create some effect fracture resistance because of uneven aggregate arrangement in mix. 3.6 Determination of Optimum Asphalt Content Based on number of experiments, the Georgia DOT suggested that if the gradation is within the specific limits, the initial estimate comes out to be 6% using granites that are native to Georgia. Hence, the probable optimum asphalt content with in this gradation band is 6% if the aggregate is Georgia granite. Depending on surface texture and angularity of aggregates, or a change in the JMF might cause changes in optimum asphalt content. Therefore, four trial percentages (5.5%, 5.8%, 6.2% and 6.5%) for each gradation, and two piles for each trial percentage are produced in this project.

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51 3.6.1 Mixing and Compaction Sieved and batched aggregates, asphalt and mineral fiber are preheated for 3 hours in an oven before mixing. Due to the SBS modified viscous asphalt and addition of mineral fiber; the mixing temperature was selected as 330 F (165 C), to maintain enough flow during mixing. All tools and mixing drum were also preheated to 350 F (176 C). While mixing, asphalt is added to mix of aggregate and mineral fiber. These SBS mixes are very sticky, making mixing and handling challenging. Therefore, it is important to ensure that while retrieving material from mixing drum there is no loss of fines. Mixing procedure was the same for both Rice testing specimens as well as the Superpave gyratory compacted specimens. It is also important to avoid over heating of binder during mixing, as it causes aging of binder. Before compaction, the mixes are subjected to Short Term Oven Aging (STOA) for two hours, which includes stirring after one hour. Compaction temperature is reduced to 320 F, for avoiding draindown of binder during compaction. As already stated, 50 gyrations were used to attain compaction level similar to field after traffic consolidation. The angle of gyration kept during compaction was 1.25. Essentially, because of sticky nature of these mixture oil is sprayed in molds. From prior experience, compacted samples are not retrieved from the molds immediately. They are allowed to cool from 1hr 45 min before retrieving from molds. Once the specimen is ejected from the mold let it cool for 5 min before holding specimen. Especially in granite mixtures if cooling after ejection is not allowed small aggregates due to high air voids stick to gloves and comes out causing discontinuity in specimen.

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52 Allow piles to cool for 24 hr before any further processing or activity related to the compacted specimens. Determination of Rice specific gravity (Gmm) on loose PFC mixes was done in accordance with AASHTO T209 (See Appendix B) Calculations of all volumetric properties are shown in Appendix B. The de termination of optimum asphalt content was as per recommended specification, as specifi ed in Chapter 3, by selecting AC at the lowest point of the VMA curve. Gradation (2) is coarser than Gradation (1 ), which results in more surface area in Gradation (1) as compared to Gradation (2). Refer to Figure 3-3 and Figure 3-4 for mix design details for Gradation (1) and Gradation (2), respectively. A decrease in effective specific gravity of Mixture 2 with respect to Mixture 1 shows the increase in volume of water permeable pores not absorbing asphalt. These facts support re duction in optimum asphalt content of Gradation (2). Essentially, the VMA at optimum asphalt content is not changing significantly for both gradations. Ba sically, Gradation (2) is giving air voids (21.93 %) similar to Gradation (1) (21.2%) and all other volumetric properties are comparable and within the restricted specifica tion ranges. Therefore, the final selection of gradation depends on fracture test results.

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53 Effective Sp Grav of Agg % AC6 Gmm1 Gmb2 VMA3 (%) VTM4 (%) VFA5 (%) 2.732 5.5 2.513 1.944 32.777 22.655 30.883 5.8 2.501 1.955 32.603 21.820 33.073 6.2 2.473 1.964 32.600 20.578 36.877 6.5 2.470 1.966 32.721 20.379 37.718 Voids in Total Mix20.0021.0022.0023.005.45.65.866.26.46.6% ACVTM Voids in Mineral Aggregates32.5532.6032.6532.7032.7532.805.45.65.866.26.46.6% ACVMA Voids filled with Asphalt30.0031.0032.0033.0034.0035.0036.0037.0038.0039.005.45.65.866.26.46.6% ACVMA Figure 3-3. Mix Design of PFC Gradation (1) with aggregate type: Granite Optimum Asphalt Content: 6.0% Gmm at Optimum Asphalt Content:2.485 Mineral Fiber: 0.4% of Total Mix VMA at Optimum Asphalt Content: 32.69% Gmm1 = Maximum specific gravity of mixture, Gmb2 = Bulk specific gravity of mixture, VMA3 = Voids in Mineral Aggregates, VTM4 = Voids in Total Mix, VFA5 = Voids filled with Asphalt, AC6 = Asphalt Content

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54 Voids filled with Asphalt30.0031.0032.0033.0034.0035.0036.0037.0038.0039.005.45.65.866.26.46.6% ACVMA % Gmm1 = Maximum specific gravity of mixture, Gmb2 = Bulk specific gravity of mixture, VMA3 = Voids in Mineral Aggregates, VTM4 = Voids in Total Mix, VFA5 = Voids filled with Asphalt, AC6 = Asphalt Content Effective Sp Grav. of Agg. % AC6 Gmm1 Gmb2 VMA3 (%) VTM4 (%) VFA5 (%) 2.722 5.5 2.497 1.935 32.819 22.501 31.440 5.8 2.494 1.946 32.648 21.963 32.727 6.2 2.479 1.953 32.713 21.245 35.057 6.5 2.452 1.957 32.788 20.212 38.357 Mineral Fiber: 0.4% of Total Mix VMA at Optimum Asphalt Content: 32.76% Optimum Asphalt Content: 5.9% Gmm at Optimum Asphalt Content:2.491 Voids in Total Mix20.0021.0022.0023.005.45.65.866.26.46.6% ACVTM % Voids in Mineral Aggregates32.6032.6532.7032.7532.8032.855.45.65.866.26.46.6% ACVMA % Figure 3-4. Mix Design of PFC Gradation (2) with aggregate type: Granite

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55 3.6.2 Asphalt Film Thickness As granite has fine texture, the surface absorption is negligible, meaning that water absorption (=0) can be assumed to be negligible. The surface areas calculated for Gradation (1) and Gradation (2) are based on the method proposed by Nukunya et al (2001 and discussed in Chapter 3. The resulting surface areas for Mixture 1 and Mixture 2 are 1.8 m^2/Kg and 1.78 m^2/Kg, respectively. Taking the total asphalt content for both gradation as the effective asphalt content the film thickness is calculated by following equation mentioned in recommended specification (Chapter 2): absWater aggefffilmWSAVT1000 (2.3) Where, 16. = Weight of aggregate aggW SA = Surface area Gradation (1) has film thickness of 33.12microns where as Gradation (2) has of 31.65 microns. These film thicknesses for Gradation (1) and Gradation (2) are calculated assuming zero asphalt absorption. Both film thicknesses are above the specified minimum film thickness requirement, i.e. 32 microns, for 0% to 0.5% asphalt absorption. The minimum film thickness requirement is to ensure resistance against stripping and asphalt hardening. 3.7 Superpave IDT Performance Test Results In the following, the results from the Superpave IDT fracture testing results are presented. The basics of the Superpave IDT test equipment and data acquisition system have been specified by Buttlar and Roque (1994), Roque et al., (1997), and AASHTO

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56 TP-9. Additional information on the specific testing system used in this study is as follows: An environmental chamber was used to control specimen temperature. The chamber is capable of maintaining temperatures between -30 C and 30 C with an accuracy of + 0.1C. Loads were controlled using a MTS Model 418.91 MicroProfiler. Vertical and horizontal deformation measurements were obtained using extensometers designed by MTS specifically for use with the Superpave IDT. A gage length of 1.5 inches was used for all specimens. Since the friction course mixtures are very porous, it was decided that the sample thickness be around 1.5 inches in order to avoid end effects. A cutting device, which has a cutting saw and a special attachment to hold the pills, was used to slice the pill into specimens of desired thickness. Two two-inch samples were obtained from each specimen. Because the saw uses water to keep the blade wet, the specimens were dried for one day at room temperature to achieve the natural moisture content. Before testing, the specimens were placed in the humidity chamber for at least two days to negate moisture effects in testing. Gage points were attached to the samples using a steel template and vacuum pump setup and a strong adhesive. Four gage points were placed on each side of the specimens at distance of 19 mm (0.75 in.) from the center, along the vertical and horizontal axes. A steel plate that fits over the attached gage points was used to mark the loading axis with a marker. This helped placing the sample in the testing chamber assuring proper loading of the specimen. Standard Superpave IDT tests were performed on all mixtures to determine resilient modulus, creep compliance, m-value, D1, tensile strength, failure strain, fracture energy, and dissipated creep strain energy to failure. The tests were performed at 10C. First,

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57 resilient modulus test was conducted on specime n. Thereafter, specimen was allowed to rest for 45 min, before creep test was conducte d, in order to regain delayed elasticity. The indirect tensile strength test was performed after the creep test. 3.7.1 Superpave Indirect Test Results and Analysis Superpave fracture testing was conducted on both mixes prepared for Gradation (1) and Gradation (2). Mixes were subjected to short-term oven aging. Even though, these porous mixtures with air voids around 21% does not hold moisture, the specimens were kept in dehumidifier for 48 hours before testi ng. The applied stress used for calculation of Energy ratio is 88.23 psi. Georgia PEM fracture test results were used as a reference to understand the mechanism of aggregate stru cture. Table 3-4 pr ovides a summary of fracture test results of Georgia PEM and I-295 PFC project mixtures. Figure 3-5 (a) through (i), show comparison of the Superpave IDT test results. The parameters presented include: Energy Ratio, Fracture Energy, Dissipated Creep Strain Energy, Failure Strain, Creep Compliance, Re silient Modulus, Strain Rate, Creep Rate and Tensile Strength between Georgia PEM and PFC mixtures. A lthough, Gradation (1) shows higher tensile strength, the Energy Ratio for Gradation (1) and Gradation (2) are 1.66 and 1.20 for Gradation (1) and Gradation (2) respectively. Because of reduction in surface area and increase in volume of water pe rmeable pores not absorbing asphalt there should be increase in film thickness in Gr adation (2) over Gradation (1). But, the reduction in optimum asphalt content counteracte d this effect. Hence the creep response, which is a measure of the visco-elastic natu re of asphalt, was about the same for both gradations. The creep compliance of Gradation (1) is 17.53 (1/Gpa), which is comparable with the creep compliance of Gradation (2) i.e. 18.07 (1/Gpa).

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58 Table 3-4. Summary of Indirect Tensile Test performed on I-295 PFC mixtures Property Stress= 88.23 p si Sample ResilientModulus(Gpa) Creep complianceat 1000 seconds (1/Gpa) Tensile Strength(Mpa) Fracture Energy (kJ/m^3) Failure Strain (10-6) m-value D1 DCSE (kJ/m^3) e0(10-6) Elastic E. (kJ/m^3) Energy Ratio Strain Rate p er Unit stress Georgia PEM 4.97 19.933 1.24 4.2 4383.2 0.74 8.35E-07 4.05 4133.73 0.154 1.95 1.1E-07 Gradatio n (1) 4.41 17.531 1.15 3.6 3940.1 0.66 1.2E-06 3.45 3679.32 0.150 1.67 7.9E-08 Gradatio n (2) 5.01 18.078 1.12 2.4 2742.3 0.71 8.9E-07 2.27 2518.79 0.125 1.21 8.6E-08

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59 Energy Ratio0.000.501.001.502.002.50GeorgiaPEMGradation(1)Gradation(2)Energy Ratio A) Fracture Energy012345GeorgiaPEMGradation(1)Gradation(2)Fracture Energy (kJ/m^3) .B) Failure Strain010002000300040005000GeorgiaPEMGradation(1)Gradation(2)Faliure Strain (10-6) C) DCSE0.001.002.003.004.005.00GeorgiaPEMGradation(1)Gradation(2)DCSE (kJ/m^3) D) Creep Compliance0510152025GeorgiaPEMGradation(1)Gradation(2)Creep Compliance (1/Gpa) E) Resilient Modulus0123456GeorgiaPEMGradation(1)Gradation(2)Resilient Modulus (Gpa) F) Strain Rate0.00E+002.00E-104.00E-106.00E-108.00E-101.00E-091.20E-09GeorgiaPEMGradation(1)Gradation(2)Strain Rate G) Tensile Strength0.000.501.001.50GeorgiaPEMGradation(1)Gradation(2)Tensile Strength (MPa) H) Figure 3-5. A)Energy Ratio, B) Failure Energy, C) Failure Strain D) DCSE, E) Creep Compliance, F) Resilient Modulus, G) Strain Rate, H) Tensile Strength I) Creep Rate

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60 Creep Rate0.00E+002.00E-104.00E-106.00E-108.00E-101.00E-091.20E-09GeorgiaPEMGradation(1)Gradation(2)Creep Rate (1/psi-sec) I) Figure 3-5. Continued Essentially, due to this reason, the resilient modulus of Gradation (1) and Gradation (2) are 4.41 Gpa and 5.01 Gpa, respectively, which are comparable magnitudes for the resilient modulus. The Georgia PEM had a creep compliance of 19.933 1/Gpa and a creep rate of 1x10^-7 1/psi-sec, which implies that the arrangement of aggregate structure is such that it is giving more room for mastic between coarse aggregate. This indicates the aggregate arrangement and interaction of coarse and fine aggregate in mixes plays an important role thus affecting the strength of Gradation (2) relative to Gradation (1). 3.8 Analysis of Fracture Result Based on Interstitial Volume and Aggregate Interaction Ongoing work at the University of Florida has led to the establishment of a tentative gradation selection framework for the optimization of the fracture resistance of dense graded mixtures. Key concepts in this new proposed framework include the observation that enhanced cracking resistance can be obtained by ensuring that the aggregates in the course portion of the mixture gradation interact sufficiently amongst each other to allow for the effective transfer of forces through the course-aggregate portion of the mixture. This interaction of the course aggregate component should not reach down to the finer materials, so as to control mixture sensitivity. The material within the interstitial volume of the course aggregate portion also needs to be proportioned and designed so that an adequate Dissipated Creep Strain Energy (DCSE)

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61 limit is maintained, as well as providing enough flow and ductility to enhance the fracture resistance of the mixture. Too little interstitial material, or interstitial material with a low creep strain rate, will result in a brittle mixture. It is anticipated that these gradation concepts will be transferable to Georgia-PEM mixtures, thus allowing for the development of guidelines for the selection of gradations that optimize the resistance to cracking. 3.8.1 Determination of Porosity and Interstitial Volume In the following, the portion of the coarse aggregate for each of the three mixtures will be evaluated, followed by a characterization of the interstitial volume component. First, the aggregate interaction curve needs to be defined: The Aggregate Interaction Curve: Aggregate interaction curve is plot of points of interaction of aggregate size with its successive aggregate size. Following is equation used for calculating points of interaction: )Re(%Re(%100*)Re(%intRe%SizeSieveattainedSizeSieveSuccesiveattainedSizeSieveattainedPonInteractioParticletained (3.1) Aggregate Interaction Curve010203040506070809010012.5-9.59.5-4.754.75-2.362.36-1.181.18-0.60.6-0.30.3-0.150.15-0.0750.075-0Contiguous sizes, mm % Retained Particle Interaction Gradation (1) Georgia PEM Gradation (2) Figure 3-6. Curve showing interaction between contiguous aggregate sizes

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62 Figure 3-6 shows the aggregate interaction curves for Georgia PEM and I-295 PFC projects. If the percent Retained Particle Interaction falls outside the range between 30% and 70% the aggregates in that size range are not interacting. Therefore, aggregate sizes below this break point are not interacting towards contribution of strength. These aggregate sizes are filling the cavities between coarse aggregate above the break points. The aggregate sizes below the break point along with asphalt are contributing to the Interstitial Volume. The range of aggregate sizes above this break point between 30%-70% is called the Dominant Aggregate Size Range (DASR). Porosity: Porosity for this DASR represents the actual porosity for the total mix. It is the ratio of summation of volume of air voids and effective asphalt in compacted mix, to volume of DASR and below. )_______)___()___(DASRbelowandDASRwithinAggregatesofVolumeAsphaltEffectiveofVolumeVoidsAirofVolumePorosity (3.2) Interstitial Volume: Mastic, comprising aggregate sizes below break point, asphalt and air voids, forms the interstitial volume of compacted mixture. The interstitial volume is the ratio of mastic in specimen to the total volume of compacted mixture. MixtureCompactedofVolumeTotalMasticofVolumeVolumealInterstiti____)__(_ (3.3) The film thickness based on Interstitial Volume (): Calculation of surface area is main issue of this method. As per the hypothesis discussed above, aggregates below the break point (i.e. aggregates within the interstitial volume) contain all of the effective asphalt volume, thus covering the coarse aggregate. The surface area (SA) of aggregates below the break point is calculated using surface area factors tabulated in Table 3-7 are calculated. As the absorption in granite is negligible, the total asphalt content is taken as effective asphalt content () of the compacted mixture. Weight of aggregates () in filmT effV aggW

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63 air is taken into account for calculating film thickness. Equation 3-1 denotes calculation of film thickness with in interstitial volume: aggefffilmWSAVT1000 (3.4) Table 3-5. Surface area factors Surface Area Factor Surface Area Sieve Size Percent Passing ft.2/lb. m2/Kg ft2/lb. m2/Kg 11/2 in.(37.5mm) 100 1 in. (25.0mm) 100 3/4 in. (19.0mm) 100 1/2 in. (12.5mm) 89 3/8 in .( 9.5mm ) 62 2.0 0.41 No. 4 (4.75mm) 15 2 0.41 0.3 0.06 No. 8 (2.36mm) 10 4 0.82 0.4 0.08 No.16 (1.18mm) 7 8 1.64 0.6 0.12 No.30 ( 600um ) 5 14 2.87 0.8 0.16 No.50 ( 300um ) 5 30 6.14 1.5 0.30 No.100 (150um ) 3 60 12.29 2.1 0.42 No.200 ( 75um ) 2 160 32.77 3.5 0.73 Aggregate with in interstitial volume Aggregate with in interstitial volume 3.8.2 Analysis and Conclusion The DASR of Gradation (1) and the Georgia PEM is 9.5-4.75 mm, resulting in porosity of 46.29% and 49.51% respectively. Table 3-6 shows the porosity and interstitial volume of all the three JMFs. Due to the interaction of 12.5 mm aggregate size with successive aggregate size, the DASR of Gradation (2) is 12.5-4.75, resulting in a porosity of 42.71%. As porosity is below 50% the mixes should perform well in strength. Similarly, due to the relatively high interaction resulting in percent retained particle interaction of 44.77 percen (see Figure 3-6) in the critical 9.5-4.75 range, the Georgia PEM mixture is expected have a higher energy ratio than Gradation (1) and Gradation

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64 (2), which had percent retained particle interaction of 35.55% and 34.85% respectively, as shown in Figure 3-6. Table 3-7 shows the interstitial volume for the three mixtures studied. The interstitial volume of Gradation (1) and Gradation (2) is comparatively the same. Therefore due to the same amount of interstitial volume component, for both gradations, it is not surprising that both gradations result in a similar creep response. Table 3-6. Porosity for all the dominant aggregate size ranges (DASR) 9.5mm 4.75mm 2.36 mm Range 12.5-9.5 9.5-4.75 12.5-4.75 4.75-2.36 9.5-2.36 12.5-2.36 Gradation (1) 74.65 46.29 42.70 52.77 42.71 39.39 Georgia PEM 71.97 49.51 46.04 50.34 38.96 36.23 Gradation (2) 73.44 47.51 42.71 53.56 43.76 39.34 The Similarly, Georgia PEM results in a higher creep compliance and strain rate due to the higher interstitial volume. Due to this reason, the DCSE threshold for Gradation (1) and Gradation (1) is reduced to 2.27 KJ/m^3 and 3.45 KJ/m^3, respectively from 4.05 Kj/m^3 for the Georgia-PEM granite. Table 3-7. Interstitial Volume for different JMFs JMF Interstitial Volume (%) Film Thickness with in Interstitial Volume (Microns) Gradation (1) 42.70 33.12 Georgia PEM 46.04 54.58 Gradation (2) 42.71 31.65 In summary, it is not possible to differentiate between the fracture performance of Gradation (1) and (2) at the low Superpave IDT test temperature of 10 C. Therefore, it was recommended that Gradation (1) be selected since the FDOT contractor had already obtained all necessary materials to run that mixture. The difference in fracture

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65 performance between Gradations (1) and (2) did not justify the selection of Gradation (2) over Gradation (1). 3.9 Verification of Locking Point of Selected Gradation for I-295 PFC Project According to Vardhan (2004) the compaction curve follows a logarithmic trend. To identify the locking point, the rate of change of slope of compaction curve was used. The stage, at which the rate of change of compaction was insignificant, was essentially the point of maximum resistance to compaction. The locking point, i.e. 49, was identified as the point at which two gyrations at same gradient of slope were preceded by two gyrations at same gradient of slope. The gradient was taken up to four decimal places (as shown in Table 3-8 for PFC-Granite mixture, Gradation (1)). Table 3-8. Locking Point Based on Gradient of Slope N umber of Gyration Gradient of Slope 39 0.0022 40 0.0020 41 0.0020 42 0.0019 43 0.0018 44 0.0017 45 0.0016 46 0.0015 47 0.0015 48 0.0014 49 (LP) 0.0014 50 0.0013 3.10 Summary and Conclusion The optimum asphalt content for Gradation (1) and Gradation (2) were determined at 6% and 5.9% respectively. The difference in fracture test parameters for both gradations is not significant. As shown in Table 3-7, the coarser portion in Gradation (2)

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66 was increased by 10% over that of Gradation (1), but the interstitial volume of both mixtures was unchanged at 42.70%. Therefore, the creep response of both mixtures is approximately the same. This implies that interaction between coarser and finer part of gradation and aggregate arrangement plays important role in optimizing fracture resistance. Gradation (1) is recommended for construction of test section at I-295 even though both gradations are performing well, as the Gradation (1) is giving higher Energy Ratio, and there was simply no justification for selecting Gradation (2) over Gradation (1).

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CHAPTER 4 A PROPOSED NEW FRACTURE TEST FOR ASPHALT MASTIC 4.1 Purpose and Need Analysis of I-295 project mixtures fracture test results shows importance of interstitial volume in the fracture performance of mixtures. Mastic within the interstitial volume, which is comprised of asphalt and aggregates below the break point of the Aggregate Interaction Curve likely has an impact on the creep and fracture response of mixtures. Therefore, it is important to be able to study the tensile strength and the fracture energy of the mastic component under direct tension loading conditions. This chapter presents the preliminary design of a new mastic fracture test. 4.2 Background A device for studying fracture initiation and crack growth in mortar was developed by Mindess & Diamond (1980). This device was modified version of work developed by Subramanian et al (1978) for study of crack growth in ceramics. The specimen configuration used by Mindesss & Diamond (1980) was similar to the compact tension described in ASTM E399 (1978): Plain-Strain fracture toughness of Metallic Material. This device functions is such a way that cracking is induced under carefully controlled conditions, so that the details of slow crack growth may be observed at high magnification in the SEM at all stages in the cracking process. This device was constructed to permit the testing of wedge-loaded compact tension. Using this device, the process of cracking was observed in mortar specimens. It was found that the process of crack extension in mortars is very complicated: the crack is tortuous, there is some 67

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68 branch cracking, discontinuities in the cracks are observed, and there is some tearing away of small bits of material in some areas of cracking. The results suggest that the simple fracture mechanics models oversimplify the geometric features of the crack extension process. 4.3 Specimen and Test Device Design The basic idea for this test is that tension can be induced by penetrating a wedge between two rollers that lie on steel rods that penetrate through the specimen. Figure 4-1 shows specimen with bearings mounted on steel rods and wedge in loading direction Figure 4-1. Model showing Specimen along with bearings fitted on steel rods and wedge in loading direction. The specimen is 32 mm long, 24 mm wide and 13 mm thick with a 13 mm long and 0.6 mm wide notch at loading side of specimen. Two 3.10 mm diameter steel rods on either side of notch were cast into specimen for applying load. Figure 4-2 and 4.3 show the geometry of the specimen. Steel rods are

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69 placed at 6 mm distance from outer edge of specimen. Steel bearings were fitted on steel rods to make friction less application of load on specimen through rods. A notch is provided in the specimen to create a stress concentration and pre-define the path of cracking. Also, without the notch, there is a slight possibility that cracks initiate at the contact area between the steel rods and the mastic, rather than in the desired center portion of the test specimen. The steel rods are extended for 6.5 mm over the specimen surface at both the top and the bottom sides of the specimen in order to avoid contact of bearing roller and the driving wedge with the specimen Figure 4-2. Plan view showing geometry of specimen

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70 Figure 4-3. Front view showing geometry of specimen The rate of loading is directly proportional to angle of wedge. As the wedge moves in forward direction, the distance between the bearings is increasing gradually, causing an increase in tension at the tip of the notch stress concentrator. Due to the roller bearings, there is no friction associated with the load transfer from the wedge to the steel rods. A mechanical system is required to propel the wedge in a forward direction. Mindess & Diamond (1980) developed a device, which uses a screw system for the driving of the wedge. Their test device is shown in Figure 4-4. It consists of a frame to support the specimen and the loading wedge; the turning of a screw advances the wedge, such that one complete rotation of the screw advances the wedge 0.64 mm. The screw feed is activated through a pulley system driven by a small electric motor and a gearbox with a reduction of 360:1. The motor is rated at 12 volts; by varying the voltage using a variable power supply, different rates of motion of the wedge can be achieved. The overall dimensions of the device are 82.6 mm long, 41.0 mm wide and 54.0 mm high.

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71 Figure 4-4. Testing Device used by Mindess & Diamond (1980) for SEM testing on cement mortar 4.4 Formulation of Tensile Force Transfer from Wedge to Specimen The rotary action of an electrical motor moves a screw through pulley action with the help of a rubber belt. One complete rotation of this screw moves the wedge for 0.64 mm in direction towards notch. The load applied on the wedge can be measured by placing a load cell at the back of the specimen. As it can be assumed that the complete system is acting as a rigid body for the determination of the balance of external forces. The load (P) on the specimen applied by wedge, is measured by a load cell located at the end of the specimen. In the following, the static analysis is presented for calculating horizontal thrust on the steel rod due to wedge loading:

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72 Taking Moment at point B, shown in Figure 4-5, results in: 0)2(xVxPa (4.1) Solving for : aV )2(xPxVa 2PVa (4.2) Where, P = Applied load on wedge aV = Vertical component of resultant Ra x = Horizontal distance between bearings As the wedge moves in the y-direction, there is a change of distance x. In the above equation there is no affect of x. The force components Va and Ha, shown in Figure 4-5 denote the the vertical and horizontal component of the reaction Ra. The angle in Equation 4-3 is the half angle of the wedge used to apply the load. Resolving forces in the horizontal direction for equilibrium at point A results in: aaRH cos (4.3) and aaRV sin (4.4) Substituting Equation 4-2 into Equation 4-4, results in: 2sinPRa Hence, solving for Ra results in: sin12PRa (4.5)

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73 Figure 4-5. Static analysis of force transfer from Wedge to Steel rods (Wedge angle = 2x ) Finally, solving for by substituting value of Ra from Equation 4-5 to 4.3 results in: aH sin12cosPHa (4.6) This means that the wedge angle ( x 2) is inversely proportional to horizontal thrust Therefore, a small wedge angle will result in a high horizontal thrust, hence minimizing the effect of the vertical component of the vertical force P. However, a small wedge angle requires a longer wedge to cause the same magnitude of horizontal aH

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74 force (tensile force) than a large angle wedge. As this specimen is designed for compact fracture testing on mastic, it may be desirable to keep the testing device as small as possible. Therefore, it is recommended to make the wedge angle at least 4-5 degrees. The final wedge designed for this study has has a wedge angle of 4.5, resulting in: PHa72.12 (For = 2.25) (4.7) Hence horizontal thrust is approximately 12 times P. 4.5 Verification of Stress States within Loaded Specimen In order to verify the stress concentration at the notch and to ensure that the sizing of the steel rods did not cause excessive bearing forces in the specimen, a finite element analysis using ADINA was performed. Considering the line of symmetry along the centerline of the notch, the specimen is divided into two half, with only one half being analyzed with ADINA. Plain stress analysis is done on 2-D model of specimen in ADINA by dividing the total surface in to 15 sub surfaces, shown in Figure 4-6. The isotropic linear elastic material finite element analysis in ADINA is done on specimen. The critical section line is divided into 170 elements with last element to first element ratio 0.25. Figure 4-7 shows meshing of sub surfaces divided. The modulus of steel adopted is 19GPa with Poisson ratio of 0.3 for the finite element analysis. The modulus of asphalt mastic at temperature 10 C is taken 4 Gpa and poisons ratio was 0.18. Essentially, while executing plain stress finite element analyses in ADINA the stress obtain at any section are irrespective to modulus. In order to keep the problem general, all results below are presented in terms of normalized loads. A horizontal thrust of 12.72 x P is applied at steel pins center. In ADINA, the load P is taken as P = 1, for simplicity. Therefore the Ha = 12.72 and Va =

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75 0.5 from Equation 4-4 and Equation 4-7. Figure 4-8 shows the exaggerated deformation of the 2-D model due to the effects of Ha and Va. Figure 4-6. Specimen 2-D Model subdivided in to 15 surfaces

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76 Figure 4-7. Meshing of 15 sub surface with critical model line divided into 175 elements. Figure 4-8. Deflection of Specimens 2-D Model subdivided.

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77 The predicted stress (yy) distribution along the centerline of the specimen is shown in Figure 4-9. As expected, the maximum stress is found at the tip of notch (yy = 273 x P/ mm2), which confirms the stress concentration effects of the notch. Stress (yy) Distribution from tip of Notch along center of specimen-50.000.0050.00100.00150.00200.00250.00300.000.500.700.901.101.301.501.701.902.10Coordinate distance (mm)Stress,yy (P/mm^2 ) Stress at Tip of Notch 273 P/mm^2 Figure 4-9. Stress distributions along centerline of specimen Tensile stress is shown as positive. Figure 4-10 shows the distribution of stresses (yy) along the circumference of the steel pins at contact with the mastic. The normalized stress distribution is a function of the load P which is applied to the wedge. Part of this contact surface facing loading is in compression. As the steel pin is loaded, the surface behind the loading area develops tension. Due to the observed stresses at the tip of notch being substantially higher than stresses at the contact surface between the mastic and the steel pins, the initiation of crack is much more likely to be at the tip of the notch.

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78 Stress distribution along circumference of Steel Pin-30.00-20.00-10.000.0010.0020.0030.000123456Circumferential distance (mm)Stress (P/mm^2) Ha =12.72 x P Va = 0.5 x P Figure 4-10. Stress distribution along circumference of steel pin 4.6 Sample Preparation Guidelines Aggregates contributing to the interstitial volume below the break point in the aggregate interaction curve, dicussed previously in section 5.5.1, are mixed with total asphalt content of the I-295 PFC mixture for preparing the mastic. Table 4-1 shows the proportion of the aggregate gradation below the breakpoint for the I-295 PFC mixture that is mixed with the 6 percent asphalt by weight of the total mixture (see Chapter 5 for mixture design details).

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79 Table 4-1. Part of fine aggregates to be mixed with total asphalt content (6%) of I-295 PFC project Sieve Size 11/2 in. (37.5mm) 1 in. (25.0mm) 3/4 in. (19.0mm) 1/2 in. (12.5mm) 3/8 in .( 9.5mm ) No. 4 (4.75mm) No. 8 (2.36mm) No.16 (1.18mm) No.30 ( 600um ) No.50 ( 300um ) No.100 (150um ) No.200 ( 75um ) Aggregate within interstitial volume Aggregate within interstitial volume The aggregates and asphalt binder are heated to 330 F 3.5 F (165 C 3.5F) for 2 hours before mixing. The aggregates are mixed with the asphalt binder using equipment as specified in AASHTO T-209-99 (2004) for mixing. The prepared mastic is molded into the desired shape, using a mold shown in Figure 4-11. Figure 4-12 shows geometry of main base plate to which side plates are attached. As the asphalt tends to bulge inside after cooling at the surface in contact with air, it is recommended that the mastic should be filled to a level slightly above the mold surface. The mold in Figure 4-10 is designed to provide a flat surface for trimming the excess mastic. First fit the steel pins and then assemble the mold into the groves of the bottom base plate and notch plate. Then, the top base plate is fitted on top and all bolts are screwed into position for a tight mold.

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80 Figure 4-11. Mold for preparing specimen for Fracture and SEM testing Figure 4-12. Geometry of main base plate to which side plates are attached

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81 4.7 Recommendation for Further Development Further work needs to be done for developing a test device and deformation measurement system. The following recommendations should be considered in further development: A trial test specimen needs to be molded using the mold shown in Figure 4-11 to check workability. A wedge angle within the range of 4% to 5% to obtain maximum horizontal thrust with optimum wedge length, is recommended.

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CHAPTER 5 PERFORMANCE TEST DATABASE (PTD) 5.1 Preface This program was developed to store and analyze data from performance testing of mixtures (Performance Test Database: PTD ). The program is entirely interactive. It is set up for easy navigation from one part of the program to another. The functionalities included are: 1) data input, 2) data extraction, 3) data export to database, 4) data analysis, and 5) report generation. All the instructions for using the tutorial are available in the help menu and users manual in order to work with the program's interface. Program details in this manual are provided for system administrators or programmers that want to understand its architecture and design, to extend or modify the PTD. 5.1.1 Package Information This package for the PTD contains the following: a) The User's Manual. b) One set of CDs labeled PTD The User's Manual contains information on how to operate the program and how to execute the commands. It also describes terminology behind programming and provides details of algorithms developed for specific task. 82

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83 5.1.2 System Requirements The minimum requirements for successfully executing the PTD program are: a) Windows2000/Me/Xp or later. b) 64 MB RAM. c) Hard disk with 2.5 MB of free space. The PTD program may be installed either onto a hard-disk system or onto a network computer system, and can also be easily uninstalled by using the provided installation software. 5.1.3 Supported Output Format Requirement The P.T.D. supports multiple report output formats. All reports are generated in a native Access format which is transformed into other output formats by Visual Basic commands. The following formats are supported : Print This output format requires a computer system connected to a printer. This format uses default printer settings. The report is printed directly using this option. Rich text format This format creates word file with a rich text format extension (.rtf) at a user specified directory. Image characters of the report are not retained in this output format. Email This output format provides the means to export a report to other systems through email. An automated function is used to send a report as an attachment to an email. This option requires that the Microsoft Outlook SendmailTM be activated. There is an option to choose the format of the report from the Rich text format, Snapshot format, Microsoft Excel Format, HTML, and MS-Dos text format.

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84 The rich text Snapshot and HTML formats are preferred as orignal alignment is maintained in the extracted data. 5.2 Program Overview The Superpave Indirect Tensile Test at Low Temperatures (ITLT) computer program can be used to analyze test data obtained from the Superpave Indirect Tensile Test. The ITLT program generates five text files, which have the following extensions: .MRO, .FAM, .OUT, .IN an .STR files. For input into the PTD database, the Data from these text files need to be extracted, analyzed and stored for a future reference. This database is designed with an aim to not only store performance test data, but also to keep track of the findings and analysis of different mix design and performance test on various materials. Extracted data from text files is reformatted in order to make storage easier in the database. The included search engine makes allows the user to customize desired queries of data and analysis results. The data and analysis results categorized according to the search criteria are then reported through report generation. Visual basic for Excel Applications was used to automate the process of data extraction and formatting in a tabular form. The flowchart in Figure 5-1 provides a complete overview on the flow of data from raw data files to storage, analysis, and final report generation. All the test readings from text files are inputted into an Excel file. There is interface, which is developed in visual basic that has categorized option for each set of test data for extracting data from text file.

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85 Raw f iles f ro m I n d i rect Ten s il e T estin g m ach in e Figure 5-1. Flow chart showing extraction and input sequence of Indirect Tensile Test Data For analysis of this data there is a customized button with caption Analyze. Once this data is extracted visual basic pop-up form comes up asking for applied stress to be used for calculating energy ratio, after which the calculation of DCSE, Elastic Energy, Analysis (VBAExcel) Database (VBAAccess) Reformatting Data I.T.L.T. output is text files (.MRO, .FAM, .OUT, .IN & .STR) Windows Based Interface MS DOS Based Interface I.T.L.T. output is excel file (New IDT format.xls) Analyzed data by I.T.L.T. Data Extraction (VBAExcel) Analysis (VBAExcel) Data Mining/Search ( S Q L ) Report Test Data (Tabulated) Material Properties (Summary and Bar charts) Report End

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86 Energy ratio and Strain rate are performed. These raw and analyzed data are exported into the database developed in Microsoft Access. The Structural Query Language (SQL) is used to develop search criteria. Search results can be retained in desired output format through a built-in visual basic environment. 5.2.1 Database Storage Outline Data stored in the database are organized for ease of retrieval. Following is the list of data and mixture properties that the database stores:1. Gradation 2. Volumetrics (Maximum specific gravtiy, Bulk specific gravity, Air voids, Absorbed asphalt, effective asphalt content, Voids in meneral aggregates, Voids filled with asphalt, N-design, Bulk specific gravity of aggregates) 3. Mixture properties:Mixture type ( Open graded Friction Course, Dense graded fine, or dense graded coarse) Aggregate Type, Mixture Source, Binder Type, Binder content and Miscelleanous 4. Superpave Indirect Tensile test data a. Resilient Modulus test data b. Creep Test data c. Strength test data 5. Superpave Indirect Test Analyzed data :Resilient modulus, Creep compliance, Tensile strain, Fracture energy, Faliure strain, D1, m-value, Dessipated creep strain energy, Elastic energy, Energy ratio. 6. Compex Modulus test and analyzed data: Stress amplitude, Strain amplitude, Dynamic modulus, Elastic modulus, Phase angle. The flow chart

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87 in Figure 5-2 depicts a brief sketch of the data flow in the program up to the report generation. 7. APA Ruth depth 5.2.2 Software Coding Architecture and Program Flow The software broadly covers to basic types of data extraction, analysis and storage first is from Indirect Tensile Test and second is Complex Modulus Test Data. Appendix C gives complete coding written to generate: Input template Macros written in Excel for specific functions are called in Main Macro of the module to attain main task. Visual Basic Form components are assigned with a command to execute these modules. The data is analyzed based on extracted data values and external input of applied stress is required to complete variables values in equations with in Macros. A common macro, which is programmed to change the Visual Basic Form Components features on completion of specific tasks, is assigned to all modules. If any changes or extension is required to the main code, this macro does not need any changes. These macrocodes are specified in Appendix C. Database Data transfer is automated using Microsoft Clipboard Unicode text format. Each line ends with a carriage return/linefeed (CR-LF) combination. A null character signals the end of the data. Data entered on screen template is automatically transferred to tables that are contented/related with other table containing their identity properties. An Access-VBA code collects all fragmented query parameters and then returns a unified SQL (Structural Query Language) statement, which generates the master query. This master query is the source for the main search result template.

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88 Database (VBAAccess) Data Mining/Search ( S Q L ) Material Properties (Summary and Bar c harts) Test Data (Tabulated) Report Report Data Extraction (VBA Excel ) Reformatting Data Complex Modulus Test Results File End Figure 5-2. Flow chart showing data input of Complex Modulus test 5.3 Installation The installation program copies the Performance Test Database software and other database supporting files into a directory. The default directory is c:\Program

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89 Files\Database. The target drive or directory name can be changed during the installation as desired. The installation also creates a Windows Program Group called PTD.exe Installation procedure: 1) Insert the CD into the CD drive. 2) Double click setup file setup.msi. 3) On the installation screen, modify the drive or directory name if desired, and then click NEXT. Figure 5-3 shows the installation screen. 4) Once installation is completed, click CLOSE for closing installation program. 5) Same setup file can be used for uninstalling or repairing the program. Figure 5-3. Installation Screen 5.4 Users Manual 5.4.1 Interaction to All Interfaces of Database The user interface for the P.T.D. is browser based. Double click PTD icon on desktop or in start menu to run program.

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90 As shown in Figure 5-1, on screen a Main Interaction form pop up. This form is means to direct user towards different part of PTD. Select the type of activity need to be carried out. Step 1: For data entry, select first option Open Input Template for data entry in database and then press OPEN button. Step 2: -Similarly for data search and report generation in different format, select second option Data Search and Report generation and then press OPEN button. Step 3: To end program press QUIT button. Browser Figure 5-4. Main Interaction Template 5.4.2 Button Function The most current functions corresponding to buttons is described as follows:

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91 Table 5-1 shows common button and there corresponding functions. All the menus, buttons, etc. conform as much as possible to the standards of Microsoft Windows Common User Access (CUA). Table 5-1. Buttons and there corresponding function Button Function Open To open an activity, define by an option selected. Quit To quit program. Input To extract data from text file as indicated and populate table. Copy To copy data from table to the clipboard as indicated. Reset Erase the data from table and reset all control properties. Main Menu To close that template and switch to main menu template. Help To access users manual. To add set of data record to database. To delete set of data record from database To navigate previous or next record. To navigate last record. End application. Search To search data records for selected query. Print Report To export search result in desired output format. 5.4.3 Data Entry Output files from I.T.L.T software are text files or Excel files. Extraction and analysis of data from the both this formats is similar. Following are the steps for inputting data from MS DOS base interface or Windows Base Interface: Step 1: Once you choose data entry option two templates are opened. First is Performance Test Database Main Menu (refer Fig) and Input Template options (refer Figure 5-5). Select the type of format of your specimen test file, whether it is MS-DOS

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92 base text files or excel file. Desired option continues to template design for specified kind of format. Both template works in same manner except the input interfaces are designed to incorporate the different files from I.T.L.T software. Figure 5-5. Input template options Step 2: As shown in Figure 5-6, page tab are provided for navigating different parts of program. Frame tags define the type of text file name and sub frame tags denote the test reading whose input is assigned to underneath button. You can access this user manual while using the program by clicking help button.

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93 Figure 5-6. MS-DOS Base text file input template Step 3: Once input button is pressed a dialog box is opened, for navigating your computer system, which is designed to open only assigned file type. In current example assigned file type is .MRO file. This provides user ease of searching file at his system. Refer Figure 5-4 for details.

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94 Figure 5-7. Input dialog box Step 4: Select file and then press open to continue. After the input process is completed a dialog box pops up (Figure 5-8) asking whether you want to save changes in opened file. Through out this program opt No for such kind of dialog box. As we dont want to change the main source files. Status of any activity is recorded and shown by changing color of button assigned. Sometimes while using this program you will face a dialog box as shown in Figure 5-6, where it asks whether to save clipboard contents. Always opt Yes for such decision boxes.

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95 Figure 5-8. Save changes dialog box Figure 5-9. Decision Box for clipboard changes.

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96 Step 5: For extracting data from different text files same procedure needs to be followed. For analyzing Indirect Tensile Test data navigate to IDT Analyzed Data using page tabs, then press analyze button which initiates an input box for applied tensile stress, as shown in Figure 5-10. The applied tensile stress is taken at the bottom of the AC layer and is very much dependent on the stiffness of the AC layer. Figure 5-10. Applied tensile stress input box

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97 5.4.4 Navigation through Input Templates and Database Once you have inputted data for all tests, these analyzed and tabulated data need to be transferred to database. For navigation between database and inputted template press key F10 and then Windows key on Key Pad. For activating Database Input Mask you have to click Input New Data button at Database main menu (Ref Figure Figure 5-11. Database Main Menu 5.4.5 Data transfer to Database Input mask (Figure 5-12) contains a set of field, which has to be entered manually. Data for particular mixture, which need to be entered in those fields, can be easily found on logbook. Use Main Menu button for closing input mask and return to database main menu.

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98 Figure 5-12. Database Input Mask While inputting data to any table in this database the correct form of tables is shown in Figure 5-13 (a). It is very essential that there is no data in input table. When there is data in table its form looks as shown in Figure 5-10 (b). Delete the data by selecting arrow head shown and right click and thereafter selecting delete option. Figure 5-13. (a) Correct state of input tables for data entry Figure 5-13. (b) Incorrect state of input tables for data entry For inputting data right click on the arrow at left side to open paste option. Select the paste option for transferring data in clipboard to the screen table linked to internal database storage area. Figure 5-13 (c) shows this process.

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99 Figure 5-13. (c) Right click projected arrow for opening paste option Figure 5-13 (d) shows confirmation of pasting data asked by Microsoft assistance. Press yes to complete the data transfer process. Figure 5-13. (d) Dialog box: After selecting paste option. Opt Yes 5.4.6 Data Search Data stored in database needs haul out in proper presentable format. Following steps describes process of data search and report generation and transferring report to different output format as per required. Step 1: Press Search button at Main Database Menu Form. Customized Microsoft assistance pops up with a dialog box. Select the type of search criteria, which is to be

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100 carried out of Materials Properties and Test Data file. Ref. Figure 5-11 for this process demonstration. Figure 5-14. Search dialog box Select type of search Step 2: Once the type of search is selected corresponding Search Form (Figure 5-15) comes on screen for entering the search criteria. Search can be made based on, ranges for quantitative parameters like Asphalt content, air voids etc, fix criteria by selecting option commands and variables. Search Button clicked with out any data entry will display all mixtures details. Figure 5-16 shows search results. Upper part of form shows properties of individual mixture in frame, and at bottom bar chart are generated comparing properties of all mixture satisfying the search criteria. Set of navigation button at right top side allows to navigate to properties of other mixture.

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101 Figure 5-15. Search form Figure 5-16. Search Result Form

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102 5.4.7 Report Generation For presentation of results produced by query, report generation and its output in desired format is developed, as shown in Figure 5-17, by pressing Print Report button and following the Microsoft Assistance directions. Figure 5-17. Report delivery option Following report delivery format are available through this software: 1. Print Report: Selection of this option leads to print of report through printer using default printer setting. 2. Create File Word: This option create rich text format file at desired location on system. 3. Email Report: For web transfer of report this option is designed. Figure 5-18 shows different types of format can be selected which are attached to automatically generated email. Note: Microsoft Snapshot format is the recommended output format for best bar chart and other graphic details.

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103 Figure 5-18. Email Report 5.4.8 Repair and Remove Program For repairing or removing the program from your PC, double click the same setup.msi file. The options on template developed on screen direct the repair and remove process. For any assistance regarding this program use, program extension and suggestion please email to contact@lokendra.us. Your queries and suggestion are important of us to improve the quality and performance of Performance Test Database, and any other software development. 5.5 Summaries and Recommendation This software is capable to support all kind of data generated for SuperpaveTM Indirect Tensile Test text files, Mixture properties, Volumetric properties, Gradation details, APA rut depth, and Complex modulus data. Software has a separated interface, which calculates fracture test parameters like energy ration, DCSE and Strain rate. Therefore it can be used has analyzes software. This software has capability to produce report in Rich text format, Snapshot format, HTML format, and Direct Print document. It is recommended to develop a Storage Area Network (SAN) for this software (P.T.D.) for developing Distributed Database Management System. This will ease data input and availability of certain information in database to global users. A Storage Area Network (SAN) is any high-performance network whose primary purpose is to enable

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104 storage devices to communicate with computer systems and with each other. Basically from single user P.T.D., data is transferred to globally accessible P.T.D. interface so that there is common set of data stored in all databse.

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CHAPTER 6 MOISTURE CONDITIONING ON I-295 PFC PROJECT The AASHTO T283 (2003) moisture conditioning protocol was adopted to evaluate the moisture sensitivity of the I-295 PFC mixture. The Superpave IDT test and associated fracture parameters were used to quantify the effects of moisture damage. 6.1 Objective Due to high air voids and dense graded pavement at bottom these porous mixtures retain water for long time. This continuous exposure to moisture at high temperature affects coarse aggregate arrangement and also causes stripping. PFC mixture if does not have sufficient resistance towards these effects, then it will lead to decrease in tensile strength. The main objective of moisture conditioning is to measure damage due to conditioning and predict resistance of mixture against moisture in actual field conditions. 6.2 Scope The scope of project for determination of moisture sensitivity is tabulated as following: Optimum asphalt content of I-295 PFC project gradation was determined and six pills of 6-inches diameter were prepared. Three for moisture conditioning and three as control samples, i.e. Unconditioned samples. Moisture conditioning was conducted, as per AASHTO T-283 (2003) protocol with modification, on three 6-inches diameter pills compacted in laboratory using Superpave gyratory compactor. SuperPave IDT was used to perform Resilient Modulus (MR), Creep Compliance, and Strength tests (13, 14, 15) for determining fracture parameters. 105

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106 6.3 Materials and Methodology 6.3.1 Aggregate and Hydrated Lime The final aggregate blend for Gradation (1) and Gradation (2) is composed of #67 Granite stone from Pit No TM-579/NS-315, #78 Granite Stone from Pit No GA-383 and Granite Screens from Pit No. TM-579/NS-315. The F.D.O.T. code for this source stone stockpiles #67 Granite, #78 Granite and Granite Screens are 54, 54 and 23 respectively. Producer of these aggregates is Martin Marietta Aggregate. Table 6-1 shows JMF used for I-295 PFC project and Figure 6-1 plot this gradation along with control points as per FDOT specification SECTION 337. Hydrated lime is added to mixture as antistrip agent, 1% by weight of aggregate. Global Stone Corporation provided hydrated Lime and its Pit No. is Luttrel Co. TENN. 6.3.2 Binder and Mineral Fiber An electrometric type of polymer modified asphalt cement PG 76-22 with 0.5% antistrip agent was used in this project. Mineral fiber used was regular FIBERAND ROAD FIBERS. Atlantic Coast Asphalt Co. supplied asphalt and mineral fiber. The dosage rate of mineral fiber was 0.4% by weight of total mix. Table 6-1. Gradation of I-295 PFC Project Sieve Size Percent Passing (%) 11/2 in. (37.5mm) 100 1 in. (25.0mm) 100 3/4 in. (19.0mm) 100 1/2 in. (12.5mm) 89 3/8 in. (9.5mm) 62 N o. 4 (4.75mm) 15 N o. 8 (2.36mm) 10 N o.16 (1.18mm) 7 N o.30 (600m) 5 N o.50 (300m) 5

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107 Table 6-1. Continued Sieve Size Percent Passing (%) N o.100 (150m) 3 N o.200 (75m ) 2 I-295, PFC Project's Selected Gradation0.010.020.030.040.050.060.070.080.090.0100.0Sieve SizesPercentage Passing (%) PFC-Granite Mixture Max Control Points Min Control Points No. No. No. No. No. No. No. 3/8" 1/2" 3/4" 200 100 50 30 16 8 4 Figure 6-1. Plot of I-295 PFC mixtures gradation 6.4 Specimen Preparation and Testing Based on number of experiments, the Georgia DOT suggested that if the gradation is within the specific limits, the initial estimate comes out to be 6%. Therefore, for gradations that control points the surface capacity (Kc) determination is not needed. The probable optimum asphalt content with in this gradation band is 6%. Depending on surface texture and angularity of aggregates and change in JMF might cause changes in optimum asphalt content. Four trial percentages (5.5%, 5.8%, 6.2% and 6.5%), and two piles for each trial percentage are produced in this project.

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108 6.4.1 Mixing and Determination of Asphalt Content Sieved and batched aggregates, asphalt and mineral fiber are preheated for 3 hours in oven before mixing. Due to viscous asphalt and addition of mineral fiber temperature of mixing selected was 330 F, to maintain enough flow during mixing. All tools and mixing drum were also preheated to maintain desired temperature. While mixing, asphalt is added to mix of aggregate and mineral fiber. These mixes are very sticky due to which it makes mixing very difficult. Ensure that while retrieving material from mixing drum there is no lose of fines. Mixing procedure was same both Rice and servopac samples. Avoid over heating of binder during mixing, as it causes aging of binder. Before compaction, mixes are subjected to Short Term Oven Aging (STOA) for two hours, which includes stirring after one hour. Compaction temperature is reduced to 320 F, for avoiding draindown of binder during compaction. As already stated, 50 gyration were used to attain compaction level similar to field. The angle of gyration kept during compaction was 1.25. Essentially, because of sticky nature of these mixture oil is sprayed in molds. From prior experience, compacted samples are not retrieved from molds immediately. They are allowed to cool from 1hr 30 min before retrieving from molds. Once the specimen is ejected from the mold let it cool for 5 min before holding specimen. Especially in granite mixtures if cooling after ejection is not allowed small aggregates due to high air voids stick to gloves and comes out causing discontinuity in specimen. Allow piles to cool for 24 hr before processing any other activity over it. Determination of Rice specific gravity (Gmm) on loose PFC mixes in accordance with AASHTO T209, Refer Appendix B, was conducted. Calculations of all volumetric

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109 properties are shown in Appendix B. The determination of the optimum asphalt content as per recommended, as specified in chapter 3, was done by selecting AC at lowest point at VMA curve. 6% is the determined optimum asphalt content for this PFC-granite mixture. 6.4.2 Volumetric Properties Figure 6-2 summarizes the volumetric properties for the mixture studied. The maximum specific gravity (Gmm) and Bulk specific gravity (Gmb) of mixture at optimum asphalt content are 2.485 and 1.957 respectively. The total air voids is designed mixture is 21.27 %. It should be noted that the effective film thickness (EFT) was developed by Nukunya et al. (9) to account for the nature of the coarse aggregate-to-aggregate contact structure in coarse-graded mixtures. Film thickness calculated as per Nukunya et al (9) is 35.4 microns. Film thickness is above specified minimum film thickness requirement, i.e. 35 microns, for 0%0.5% asphalt absorption. The minimum film thickness requirement is to ensure resistance against stripping and asphalt hardening. This indicates mixture have sufficient asphalt content. 6.4.3 Moisture Conditioning and Testing Three samples were then subjected to saturation according to the AASHTO T-283 (2003) procedure, with the following modifications: 9. Since the PFC mixture has air voids around 21%, it is possible that the specimens creep during or fail during moisture conditioning. To over come this problem, the specimens were wrapped in 1/8 mesh and two clamps are provided without exerting pressure. 17. Wire mesh wrapped specimen is vacuum saturated at 25 inches of Hg absolute suction pressure for 30 minutes at a temperature of 25C. This allows water to penetrate into specimen, intercepting pocket of mastic. The vacuum saturation setup is shown in Figure 6-4.

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110 18. Vacuum saturated samples are immersed in preheated water bath at 60C 1C temperature. Samples are conditioned in hot water bath for 24 1 hour. 19. After 24 hours samples are moved to water ba th with temperature 25 0.5C for 2 hours. Conditioned samples are kept 36 hours for draining all water before removing the wire mesh. Once the specimens had drained for 36 hours, both the conditioned and unconditioned specimens were cut, by a wet saw, into 2-inch thick specimens. The specimens were placed in a dehumidifier ch amber for 48 hours. This ensured that the surface of the specimen was dry. SuperPave IDT was used to perform Resilient Modulus (MR), Creep Compliance, and Strength te sts (13, 14, 15) from which the following properties were determined: tensile strength, resilient m odulus, fracture energy limit (FE), dissipated creep strain energy limit (DCSE), creep compliance, and m-value. The FE and DCSE values and the modulus can be accurately determined using the SuperPave Indirect Tensile Test following the procedures developed by Roque and Buttlar, and Buttlar and Roque (16, 17). Us ing these mixture properties and the HMA fracture mechanics framework developed at the University of Florida (Roque et al., 2004), the Energy Ratio was calculated.

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111 Gmm1 = Maximum specific gravity of mixture, Gmb2 = Bulk specific gravity of mixture, VMA3 = Voids in Mineral Aggregates, VTM4 = Voids in Total Mix, VFA5 = Voids filled with Asphalt, AC6 = Asphalt Content Voids filled with Asphalt30.0031.0032.0033.0034.0035.0036.0037.0038.0039.005.45.65.866.26.46.6% ACVFA Effective Film Thickness (EFT) as per Nukunya et al for PFC-mixture with optimum asphalt content: 35.4 microns Effective Sp Grav of Agg % AC6 Gmm1 Gmb2 VMA3 (%) VTM4 (%) VFA5 (%) 2.732 5.5 2.513 1.944 32.777 22.655 30.883 5.8 2.501 1.955 32.603 21.820 33.073 6.2 2.473 1.964 32.600 20.578 36.877 6.5 2.470 1.966 32.721 20.379 37.718 Mineral Fiber: 0.4% of Total Mix VMA at Optimum Asphalt Content: 32.69% Optimum Asphalt Content: 6.0% Gmm at Optimum Asphalt Content:2.485 Voids in Total Mix20.0021.0022.0023.005.45.65.866.26.46.6% ACVTM Figure 6-2. Mix Design of I-295 PFC-Granite mixture Voids in Mineral Aggregates32.5532.6032.6532.7032.7532.8055.566.57% ACVMA

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112 Figure 6-3. Compacted pill rolled in 1/8 inch sample placed in vacuum chamber Figure 6-4. Vacuum Saturation of sample prior to moisture conditioning 6.5 Fracture Test on Moisture condition Moisture conditioning causes sever damage to strength of mixture therefore it is essential to handle sample carefully during testing for obtaining consistent results. In order to avoid end effects due to porous nature of OGFC and PFC mixtures, the Superpave IDT specimen thickness to be cut from compacted pill was kept around 1.5

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113 inches.After cutting, all specimens were allowed to dry in a constant humidity chamber for a period of two days. Figure 9.5 shows a picture of the dehumidifying chamber used. Four brass gage points (5/16-in. diameter by 1/8-in. thick) were affixed with epoxy to each specimen face. The strain gage extensometers were mounted on the specimen. Horizontal and vertical deformations were measured on each side of the specimen. Since the PFC air voids content is very high (around 18-22%), handling of the specimens at room temperature could cause specimen damage. Therefore specimens with glued gauge points were placed in a cooling chamber at a temperature 10 0.5 C for at least 3 hours before attaching the strain gage extensometers to the specimens. Without this step, occasional loss of gauge points, along with stone or mastic, was experienced, thus compromising the specimen for further testing. The test specimen was placed into the load frame. A seating load of 5 to 8 pounds was applied to the test specimen to ensure proper contact of the loading heads. As mentioned earlier, a 45-minute rest period was allowed between tests at different frequencies. Start up load for resilient modulus test was kept around 60 % of load applied on unconditioned sample during resilient modulus test to obtain resilient deformation of 100 microns (instead of 100-180 microns). If initial load applied is high it damages specimen in resilient test itself. 6.5.1 Findings and Analysis Moisture conditioning was done in water bath of 60C for 24 hours on I-295 PFC samples. At such a high temperature and due negligible surface absorption capacity of granite mixture asphalt tends to flows with in mixture. Table 6-2 shows summary of fracture testing result of the conditioned and un-conditioned sample. Creep compliance of conditioned mix is 17.66 1/Gpa, which is not a significant change as compared to unconditioned sample i.e. 17.53 1/Gpa. The strain rate per unit

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114 stress of unconditioned sample, i.e. 7.9 x 10^-8 1/psi-sec, remains same after conditioning. This indicates that the asphalt with in is not affected from the conditioning substantially. Where as, the threshold limit DCSE had reduced from 3.45 KJ/m^3 to 1.03 KJ/m^3 due to conditioning. Fracture energy also plummet from 3.6 KJ/m^3 to 1.1 KJ/m^6 as result of conditioning. Probably, as granite is not absorbing asphalt and asphalt at such a high temperature is in liquid state, the reinforcement of mixture due to stone to stone contact is affected as shown in Figure 6-5. Therefore the failure strain is reducing around half as compared to unconditioned sample. The energy ratio, calculated as per Roque et al (2004), of conditioned specimen is 0.6, which is good value as compared with energy ratio, i.e. 1.67, of unconditioned sample. Resilient modulus is increased to 5.25 Gpa from 4.41 Gpa, due to conditioning but this change is not significant. This confirms the constant strain rate and creep compliance. Figure 6-5. Affect of conditioning over stone to stone contact of PFC mixtures

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115 Table 6-2. Summary of fracture test on moisture condition sample compared with unconditioned sample Property Sample Resilient Modulus(Gpa) Creep complianceat 1000 seconds (1/Gpa) Tensile Stren g th(Mpa) Fracture Energy (kJ/m^3) Failure Strain (10-6) m-value D1 DCSE (kJ/m^3) e0(10-6) Elastic E. (kJ/m^3) Ener gy Ratio Strain Rate per Unit stress (1/psi-sec) Creep Rate (1/psi-sec) Unconditioned 4.41 17.53 1.15 3.6 3940 0.66 1.16E-06 3.45 3679.32 0.150 1.67 7.916E-08 8.86E-08 Conditioned 5.25 17.67 0.84 1.1 1827 0.73 7.9E-07 1.03 1666.89 0.067 0.60 8.827E-08 8.91E-08

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116 Energy Ratio0.000.501.001.502.00UnconditionedConditionedEnergy Ratio A Fracture Energy01234UnconditionedConditionedFracture Energy (kJ/m^3) B Tensile Strength01234UnconditionedConditionedTensile Strength (MPa) C Failure Strain010002000300040005000UnconditionedConditionedFaliure Strain (10-6) D DCSE0.001.002.003.004.00UnconditionedConditionedDCSE (kJ/m^3) E Creep Compliance0.005.0010.0015.0020.00UnconditionedConditionedCreep Compliance (1/Gpa) F Figure 6-6. Comparison of Fracture Test rsults A) Energy ratio, B) Fracture energy, C) Tensile strength, D) Failure strain, E) DCSE, F) Creep compliance, G) Resilient modulus, H) Strain rate, I)Creep rate

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117 Resilient Modulus0123456UnconditionedConditionedResilient Modulus (Gpa) G) Strain Rate0.00E+002.00E-104.00E-106.00E-108.00E-101.00E-09UnconditionedConditionedStrain Rate(in/in) H) Creep Rate0.00E+002.00E-104.00E-106.00E-108.00E-101.00E-09UnconditionedConditionedCreep Rate (1/psi-sec) .I) Figure 6-6. Continued 6.6 Summary and Conclusion The energy ratio is reduced 0.6 from 1.67. Initial energy ratio of unconditioned indicates good field performance. Moisture conditioning procedure was to sever because of the warm water soaked in vacuum saturated specimen. This could have developed internal water pressure. Even though, after under going this conditioning liberation of energy ratio 0.6 is indicting good field performance. Finally, sample is still in good shape to with stand further conditioning, indicating good field performance of mixture for I-295.

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CHAPTER 7 SUPERPAVE IDT FRACTURE TEST RESULTS In this chapter, all Superpave IDT fracture test results from US-27 and I-295 project are presented and compared with an aim to evaluate the fracture performance of these mixtures. 7.1 Materials 7.1.1 Aggregate and Hydrated Lime Two types of aggregate are used for the development of Georgia PEM for Florida condition i.e. Granite and Limestone. Nova Scotia granite and oolitic limestone from South Florida (White Rock) were used for preparing the mixtures. Same JMF is used for both granite and limestone mixture composing of aggregates from different stockpiles. Job mix formula of granite was composed of aggregates from stockpiles #7, #789 and Granite Screens. Job mix formula of limestone was composed of aggregates from stockpiles S1A, S1B and limestone screens. Hydrated lime (1% by weight of aggregate) was used as anti stripping agent for granite aggregates. FC-5 limestone and FC-5 granite are composition of stockpiles as shown in Appendix F. Hydrated lime is added to FC-5 Granite mixture with a dosage rate of 1%. Table F.2 of appendix show JMF of FC-5 granite with 1 % limestone. The final aggregate blend for I-295 Permeable Friction Course (PFC) project is composed of #67 Granite stone from Pit No TM-579/NS-315, #78 Granite Stone from Pit No GA-383 and Granite Screens from Pit No-TM-579/NS-315. The F.D.O.T. code for this source stone stockpiles #67 Granite, #78 Granite and Granite Screens are 54, 54 and 23 118

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119 respectively. Producer of these aggregates is Martin Marietta Aggregate. Hydrated lime is added to mixture as antistrip agent, 1% by weight of aggregate. Global Stone Corporation provided hydrated Lime and its Pit No. is Luttrel Co. TENN. Figure 7-1 shows Gradation used for Georgia PEM and I-295 PFC project. Gradations of Georgia PEM and I-295 PFC Project0102030405060708090100Sieve SizesPercentage Passing (%) Georgia PEM Granite and Limestone I-295 PFC Granite Mixture No. No. No. No. No. No. No. 3/8" 1/2" 3/4" 200 100 50 30 16 8 4 Figure 7-1. Gradation Band of Georgia PEM and I-295 PFC Project 7.1.2 Binder and Mineral Fiber SBS modified PG 76-22 asphalt, with 0.5% anti strip agent was used in the mixture design. Mineral fiber (Fiberand Road Fibers) supplied by SLOSS Industries, Alabama, 0.4% by weight of total mix, was added to mix in order to avoid binder drain drown. Chemical composition of mineral fiber is Vitreous Calcium Magnesium Aluminum Silicates. Mineral fibers were shredded into fine fragments before adding to mix. An electrometric type of polymer modified asphalt cement PG 76-22 with 0.5% antistrip agent was used in I-295 PFC project. Mineral fiber used was regular FIBERAND ROAD FIBERS. Atlantic Coast Asphalt Co. supplied asphalt and mineral fiber. The dosage rate of mineral fiber was 0.4% by weight of total mix.

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120 7.2 Test Method SuperPaveTM IDT was used to perform Resilient Modulus (MR), Creep Compliance, and Strength tests (14, 15) from which the following properties were determined: tensile strength, resilient modulus, fracture energy limit (FE), dissipated creep strain energy limit (DCSE), creep compliance, and m-value. The FE and DCSE values and the modulus can be accurately determined using the SuperPave Indirect Tensile Test following the procedures developed by Roque and Buttlar, and Buttlar and Roque (16, 17). Using these mixture properties and the HMA fracture mechanics framework developed at the University of Florida, the Energy Ratio was calculated (Roque, et al, 2004). 7.2.1 Sample Preparation Both OGFC and PFC mixtures are very porous. Therefore both the long-term oven aging procedure and the Superpave IDT test procedure that was developed for dense-graded mixtures by Roque and Buttlar (1992) cannot be used unmodified. In the following, the long-term oven aging procedure used will be discussed, followed by a discussion on the Superpave IDT sample preparation and test procedures used. Long-Term Oven Aging Procedure The PFC and OGFC mixtures were subjected to long-term aging according to AASHTO PP2 (1994). However, the mixtures being very course and open, there was a possibility of these mixtures flowing or even falling apart during aging. Hence, the following procedure was developed to contain the compacted pills from falling apart during aging: 1. A 1/8 inch opening wire mesh is rolled around pills, with two tightening clamps located on each side of the specimen, at a distance of 1 inch from the top and bottom of the specimen, respectively. The mesh size was chosen to ensure that

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121 there is good circulation of air within the sample for oxidation and at the same time, to prevent the smaller aggregate particles from falling through the mesh. 2. Following AASHTO PP2, the specimens are kept in an oven with porous plate at bottom for 185 F 5.4 F (85 C 3 C) for 120 0.5 hours. 3. After that time period, the oven is turned off and the doors are opened to allow the oven and specimens to cool to room temperature for 16 0.5 hours. 7.2.2 Testing Equipment The basics of the Superpave IDT test equipment and data acquisition system have been specified by Buttlar and Roque (1994), Roque et al., (1992), and AASHTO TP-9. Figure 7-2 shows a picture of the Superpave IDT testing setup used. Additional information on the specific testing system used in this study is as follows: An environmental chamber was used to control specimen temperature. The chamber is capable of maintaining temperatures between -30 C and 30 C with an accuracy of + 0.1C. Figure 7-3 shows a picture of the environmental chamber used. Loads were controlled using a MTS Model 418.91 MicroProfiler. The data acquisition system used was Labtech Notebook Pro software. A data acquisition program written specially for complex modulus tests. Approximately 50 data points per loading cycle were obtained. Vertical and horizontal deformation measurements were obtained using extensometers designed by MTS specifically for use with the Superpave IDT. A gage length of 1.5 inches was used for all specimens. Figure 7-4 shows a picture of the extensometers used.

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122 Figure 7-2. IDT testing device Figure 7-3. Temperature controlled chamber

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123 Figure 7-4. Typical Dense-Graded specimen with extensometers attached 7.2.3 Specimen Preparation and Testing Procedure Test specimens were obtained from 6-in. diameter specimens that were compacted to 50 gyrations with the Superpave gyratory compactor. Each Superpave gyratory compacted specimen yielded two Superpave IDT specimens. Three specimens were tested at each of three test temperatures for each mixture. Additional details on the testing procedure used are as follows: In order to avoid end effects due to porous nature of OGFC and PFC mixtures, the Superpave IDT specimen thickness to be cut from compacted pill was kept around 1.5 in. After cutting, all specimens were allowed to dry in a constant humidity chamber for a period of two days. Figure 7-5 shows a picture of the dehumidifying chamber used. Four brass gage points (5/16-in. diameter by 1/8-in. thick) were affixed with epoxy to each specimen face. The strain gage extensometers were mounted on the specimen. Horizontal and vertical deformations were measured on each side of the specimen. Since the PFC

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124 air voids content is very high (around 18-22%), handling of the specimens at room temperature could cause specimen damage. Therefore specimens with glued gauge points were placed in a cooling chamber at a temperature 10 0.5 C for at least 3 hours before attaching the strain gage extensometers to the specimens. Without this step, occasional loss of gauge points, along with stone or mastic, was experienced, thus compromising the specimen for further testing. The test specimen was placed into the load frame. A seating load of 5 to 8 pounds was applied to the test specimen to ensure proper contact of the loading heads. As mentioned earlier, a 45-minute rest period was allowed between tests at different frequencies. Figure 7-5. Dehumidifying chamber 7.2.4 Test Procedures and Analysis of Test Results Standard Superpave IDT tests, as specified by Roque & Butlar (1992) were performed on all mixtures to determine resilient modulus, creep compliance, m-value, D1, tensile strength, failure strain, fracture energy, and dissipated creep strain energy to failure. The tests were performed at 10C. Resilient Modulus Test The resilient modulus is defined as the ratio of the applied stress to the recoverable strain when repeated loads are applied. The test was conducted according to the system

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125 developed by Roque & Butlar (1992) to determine the resilient modulus and the Poissons ratio. The resilient modulus test was performed in load control mode by applying a repeated haversine waveform load to the specimen for a 0.1 second followed by a rest period of 0.9 seconds. The load was selected to keep the horizontal strain in the linear viscoelastic range, in which horizontal strain is typically 100 to 180 micro-strains. The procedures for resilient modulus test are as follows: 1. The specimens compacted are cut parallel to the top and bottom faces using a water-cooled masonry saw to produce 2 inches thick specimens having smooth and parallel faces. 2. Four aluminum gage points are affixed with epoxy to each trimmed smooth face of the specimen. 3. Test samples are stored in a humidity chamber at a constant relative humidity of 60 percent for at least 2 days. In addition, specimens are cooled at the test temperature for at least 3 hours before testing. 4. Strain gauges are mounted and centered on the specimen to the gage points for the measurement of the horizontal and vertical deformations. 5. A constant pre-loading of approximately 10 pounds is applied to the test specimens to ensure proper contact with the loading heads before test loads are applied. Applying a repeated haversine waveform load for five seconds to obtain horizontal strain between 100 to180 micro-strains then tests the specimen. If the horizontal strains are higher than 50 micro-strains, the load is immediately removed form the specimen, and specimen is allowed to recover for a minimum 3minutes before reloading at different loading level. 6. When the applied load is determined, data acquisition program begins recording test data. Data are acquired at a rate of 150 points per seconds. 7. The resilient modulus and Poissons ratio are calculated by the following equations, which were developed based on three dimensional finite element analysis by Roque and Buttlar (11). The equation is involved in the Superpave Indirect Tensile Test at Low Temperatures (ITLT) program, which was developed by Roque & Butlar (1994). P GL H t D C co m p MR=

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126 Where, MR = Resilient modulus P = Maximum load GL = Gauge Length H = Horizontal Deformation t, D = Thickness, Diameter Ccomp = 0.6354 (X/Y)-1-0.332 Creep test Creep compliance is a function of time-dependent strain over stress. The creep compliance curve was originally developed to predict thermally induced stress in asphalt pavement. However, because it represents the time-dependent behavior of asphalt mixture, it can be used to evaluate the rate of damage accumulation of asphalt mixture. As shown in Figure 5-5, D0, D1, and m-value are mixture parameters obtained from creep compliance tests. Although D1 and m-value are related to each other, D1 is more related to the initial portion of the creep compliance curve, while m-value is more related to the longer-term portion of the creep compliance curve. The m-value has known to be related to the rate of damage accumulation and the fracture resistance of asphalt mixtures. In other words, the lower the m-value, the lower the rate of damage accumulation. However, mixtures with higher m-value typically have higher DCSE limits. The creep compliance is a time dependant strain, (t), divided by a constant stress. That is, the inverse of the creep compliance, which is called creep

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127 stiffness, is a kind of stiffness. According to the analysis conducted by Roque & Butlar (1994), MR is higher than creep compliance stiffness at 1 second. The Superpave Indirect Tensile Test at Low Temperatures (ITLT) computer program was used to determine creep properties of the mixtures. The test was conducted in a load control mode by applying a static load. The load was selected to keep the horizontal strain in the linear viscoelastic range, which is below a horizontal strain of 180 micro strains at 100 seconds and 750 microns at 1000 seconds. The test procedure was presented by Roque & Butlar (1992). The procedures for indirect tensile creep test consist of the following steps: The preparation of test samples and the pre-loading are same as those for resilient modulus test Apply a static load for 1000 seconds. If the horizontal deformation is greater than 180 micro inch at 100 seconds, the load is immediately removed from the specimen, and specimen is allowed to recover for a minimum 3 minutes before reloading at a different level. At 100 sec, the horizontal deformation should be less than 750 micro inches When the applied load is determined, the data acquisition program records the loads and deflections at a rate of 10 Hz for the first 10 seconds, 1Hz for the next 290 seconds, and 0.2 Hz for the remaining 700 seconds of the creep test. The computer program, ITLT, was used to analyze the load and deflection data to calculate the creep compliance properties. Creep compliance and Poissons ratio are computed by the following equations. = -0.1+1.480 (X/Y) 2 0.778 (t/D)2 (X/Y)2 Where, D (t) = Creep Compliance P GL D( t ) = H t D Ccom p

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128 Strength test Failure limits such as tensile strength, failure strain, and fracture energy were determined from strength tests using the Superpave IDT. These properties are used for estimating the cracking resistance of the asphalt mixtures. The strength test was conducted in a displacement control mode by applying a constant rate of displacement of 50 mm/min for field mix and 100 mm/min for saturated mix until the specimens failed. The horizontal and vertical deformation and the applied load are recorded at the rate of 20 Hz during the test. The maximum tensile strength is calculated as the following equation. b d 2 P C sx S t = Where, St = Maximum Indirect tensile Strength P = Failure load at first crack Csx = 0.948 0.01114 (b/D) 0.2693 + 1.436 (b/D) b, D = Thickness, diameter

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129 Figure 7-6. Power Model for Creep Compliance

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130 From the strength test and the resilient modulus test, fracture energy and dissipated creep strain energy can be determined. Fracture energy is a total energy applied to the specimen until the specimen fractures. Dissipated creep strain energy (DCSE) is the absorbed energy that damages the specimen, and dissipated creep strain energy to failure is the absorbed energy to fracture (DCSEf). As shown in the Figure 7-7, fracture energy and DCSEf can be determined as described below. The ITLT program also calculates fracture energy automatically. MR = & 0 = MR f-St S t f 0 MR Elastic Energy (EE) = () St (f 0) Fracture energy (FE) = St () d (Upper Limit of strain is Faliure strain f, Refer Figure 7-7) f 0 Dissipated Creep Strain energy (DSCE) = FE EE Where, St = Tensile Strength f = Failure Tensile Strain 0 = Elastic Strain MR = Resilient Modulus

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131 Figure 7-7. FE and DCSE from Strength Test 7.2.5 Results of Fracture Testing on PFC Mixtures The short-term oven aged and long-term oven aged test results for the PFC friction courses are presented in Table 7-1 and Figure 7-8 through 7-16, along with a comparison with results from the OGFC mixtures from US Hwy 27, Highlands County. Below, the short-term oven aged and the long-term oven aged results are discussed briefly. Discussion of results for short-term oven aged mixtures The original GPEM mixture designs in this project used NS315 aggregate from Nova Scotia and oolitic limestone from South Florida, with an existing gradation obtained from the GDOT. Hence, these two mixtures are entitled GPEM (Granite) and GPEM (Limestone), respectively. The mixture entitled PFC (granite) is the mixture that was designed for the test section on I-295, Jacksonville. Finally, the granite and limestone OGFC mixtures from US Hwy 27, Highlands County are shown for comparison purposes.

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132 The Energy ratio for short-term oven aged Georgia PEM-G (Granite) and PFC-G (Granite) ranges from between 1.5 and 2, which indicates good field performance. Similarly, for the GPEM (Limestone) mixture, the short-term oven aged energy ratio is around to 3.5. In the case of GPEM (Granite), the short-term oven aged failure strain is around 4000 micro strain and the DCSE limit is close to 4 KJ/m3. In comparison, the short-term oven aged GPEM (Limestone) had a DCSE limit of 3.28 KJ/m3. This lower DCSE limit is primarily due to the low failure strain 2735 micro strain as compared with granite mixture (4000 micro strain). For the short-term oven aged PFC-G the DCSE limit is 3.5 KJ/m3 with a failure strain of 3940 micro strains. Discussion of results for long-term oven aged mixtures All granite mixtures showed a decrease in the energy ratio due to long-term aging. As shown in Figure 7-10 the failure-strain of the granite mixtures was reduced by half, as compared to the short-term oven aged mixtures. This decrease in the failure strain led to a decrease in the DCSE limit. The resilient modulus for the long-term oven aged mixtures is not affected significantly when compared with short-term oven aged mixtures. Interestingly, limestone mixtures in general have a rough texture, with a lot of crevices and pores on the aggregate surfaces. During the long-term oven aging, the temperature is around 85 C, and at such a high temperature, the asphalt will flow, further enhancing the absorption of the asphalt into the crevices and the pores in the aggregate. This absorption mechanism may result in a mixture with enhanced ductility and failure strains, thus resulting in higher energy ratios. For example, in the extreme, the FC-5 Limestone mixture showed a significant increase in the energy ratio from 1.62 to 3.57,

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133 due to an increase in both failure strain and fracture energy. This shows that FC-5 limestone has sufficient cavities to absorb flowing asphalt. Interestingly, the GPEMLimestone has a high-energy ratio for short-term oven aged conditions of about 3.3, and only a slightly reduced energy ratio of 3.09 for the long-term oven aged conditions. It is possible that the added mineral fiber is play ing a role in reducing the absorption during long term oven aging, along with the SBS m odified asphalt, which tends to be stickier than the ARB-12 asphalt.

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134 Table 7-1. Summary of Fr acture Test results on Short-Term an d Long-Term Oven Aged Mixtures of Georgia PEM, PFC Project and OGFC Mixture Property Sample Resilient Modulus (Gpa) Creep compliance at 1000 seconds (1/Gpa) Tensile Stren g th (Mpa) Fracture Energy (kJ/m^3) Failure Strain (10-6) m-value D1 DCSE (kJ/m^3) e0(10-6) Elastic E. (kJ/m^3) Energy Ratio Strain Rate per Unit stress (1/psi-sec) Short-Term Oven Aged Mixtures GPEM-G 4.97 19.93 1.24 4.2 4383 0.74 8.35E-07 4.05 4133.73 0.154 1.95 1.061E-07 GPEM-L 5.81 3.54 1.59 3.5 2735 0.51 6.75E-07 3.28 2461.61 0.22 3.32 1.161E-08 FC-5 G 4.98 7.23 1.16 3 3248 0.60 7.84E-07 2.86 3014.79 0.14 1.59 2.896E-08 FC-5L 7.35 1.88 1.11 0.9 982.1 0.48 4.29E-07 0.82 831.50 0.08 1.62 5.808E-09 PFC-G 4.41 17.53 1.15 3.6 3940 0.66 1.16E-06 3.45 3679.319 0.150 1.67 7.916E-08 Long-Term Oven Aged Mixtures GPEM-G 4.9 10.93 0.97 1.1 1552 0.70 5.86E-07 1.00 1354.31 0.10 0.86 5.127E-08 GPEM-L 6.27 2.47 1.57 2.3 2026 0.34 1.59E-06 2.10 1775.57 0.20 3.09 5.536E-09 FC-5 G 4.81 8.74 0.89 1 1454 0.77 2.80E-07 0.92 1268.76 0.08 0.68 4.567E-08 FC-5L 7.57 1.81 1.69 2.1 1609 0.43 5.92E-07 1.91 1385.89 0.19 3.57 4.972E-09 PFC-G 3.28 27.91 0.94 1.6 2349 0.692 1.56E-06 1.47 2062.21 0.135 0.49 1.283E-07

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135 Energy Ratio0.000.501.001.502.002.503.003.504.00FC-5 G FC-5 L PFC-GraniteGPEM(Granite)GPEM (Limestone)ER Short-Term Oven Aged Long-Term Oven Aged Figure 7-8. Energy Ratio Fracture Energy0.000.501.001.502.002.503.003.504.004.50FC-5 G FC-5 L PFC-GraniteGPEM (Granite)GPEM (Limestone)FE (KJ/m3) Short-Term Oven Aged Long-Term Oven Aged Figure 7-9. Fracture Energy

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136 Faliure Strain0.0500.01000.01500.02000.02500.03000.03500.04000.04500.05000.0FC-5 G FC-5 L PFC-GraniteGPEM(Granite)GPEM (Limestone)Faliure Strain (in/in) Short-Term Oven Aged Long-Term Oven Aged Figure 7-10. Failure Strain DCSE0.000.501.001.502.002.503.003.504.004.50FC-5 GFC-5 LPFC-GraniteGPEM(Granite)GPEM(Limestone)DCSE (KJ/m3) Short-Term Oven Aged Long-Term Oven Aged Figure 7-11. DCSE

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137 Resilient Modulus0.001.002.003.004.005.006.007.008.00FC-5 G FC-5 L PFC-GraniteGPEM(Granite)GPEM (Limestone)Mr (1/GPa) Short-Term Oven Aged Long-Term Oven Aged Figure 7-12. Resilient Modulus Creep Compliance0.00E+005.00E+001.00E+011.50E+012.00E+012.50E+013.00E+01FC-5 G FC-5 L PFC-GraniteGPEM(Granite)GPEM (Limestone)Creep Rate (1/Gpa) Short-Term Oven Aged Long-Term Oven Aged Figure 7-13. Creep Compliance

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138 Strain Rate00.000000020.000000040.000000060.000000080.00000010.000000120.00000014FC-5 G FC-5 L PFC-GraniteGPEM(Granite)GPEM (Limestone)Strain Rate (1/psi-sec) Short-Term Oven Aged Long-Term Oven Aged Figure 7-14. Strain Rate D10.00E+005.00E-071.00E-061.50E-062.00E-06FC-5 G FC-5 L PFC-GraniteGPEM(Granite)GPEM (Limestone)D1 Short-Term Oven Aged Long-Term Oven Aged Figure 7-15. Power Model Parameter (D1)

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139 m00.10.20.30.40.50.60.70.80.9FC-5 G FC-5 L PFC-GraniteGPEM(Granite)GPEM (Limestone)m Short-Term Oven Aging Long-Term Oven Aging Figure 7-16. Power Model Parameter (m) 7.3 Summary and Conclusion Summary and conclusion of findings and analysis of Superpave IDT fracture test results are as follows: All limestone short-term oven aged mixtures are showing higher energy ratio as compared with granite short-term oven aged mixture. Due to absorption of asphalt in FC-5 limestone mixture during long-term oven aging, ductility is increased resulting in higher failure strain and energy ratio. Where as in GPEM limestone mixture use of SBS modified mixture, which is stickier than AR-12, and mineral fiber is reducing absorption of flowing asphalt at high temperature. Therefore, there is slight reduction in failure strain and energy ratio with approximately same tensile strength as compared with short-term oven aged samples. All granite mixture show substantial drop in failure strain, failure energy and energy ratio due to long-term oven aging. GPEM-granite and PFC-granite short-term oven aged mixture posses highest failure strain, fracture energy and energy ratio, as compared with FC-5 granite. Same mixtures is showing highest drop, more than 50%, in energy ratio, failure strain and fracture energy ratio.

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APPENDIX A SAMPLE CALCULATION OF VOLUMETRICS FOR GPEM AND PFC MIXTURE Table A-1. Gradation for Georgia PEM-Granite Type #7 #789 Granite Granite Screens Lime JMF Control Points % Amount 55 37 7 1 100 Max Min Sive Size Size^0.45 37.5 5.11 100 100 100 100 100 25 4.26 100 100 100 100 100 19 3.76 100 100 100 100 100 100 100 12.5 3.12 82 100 100 100 90 100 80 9.5 2.75 28 99 100 100 60 60 35 4.75 2.02 2 39 99 100 23 25 10 2.36 1.47 2 6 69 100 9 10 5 1.18 1.08 2 2 46 100 6 0.6 0.79 1 1 30 100 4 0.3 0.58 1 1 17 100 3 0.15 0.43 0 1 7 100 2 0.075 0.31 0 0 1 100 1 4 1 Table A-2. Bulk Specific Gravity for Georgia PEM-Granite AC (%) Number Height (cm) Weight (gms) Bulk Specific Gravity Avg Bulk Specific Gravity 5.5 1 13.668 4659.3 1.930 1.936 2 13.618 4657.1 1.936 3 13.586 4658.3 1.941 6.0 1 13.539 4682.0 1.958 1.961 2 13.557 4683.0 1.956 3 13.468 4681.5 1.968 140

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141 Table A-2. continued AC (%) Number Height (cm) Weight (gms) Bulk Specific Gravity Avg Bulk Specific Gravity 6.5 1 13.583 4704.9 1.961 1.967 2 13.449 4701.8 1.979 3 13.598 4707.1 1.960 Table A-3. Rice Test for Georgia PEM-Granite % A/C 5.5 6 6.5 Wt. Flask+Sample 2876 2867.6 2884.5 2851.7 2892 2892.6 Wt Flask 1872.9 1872.9 1875.7 1844.8 1872.9 1872.9 Wt Sample (A) 1003.1 994.7 1008.8 1006.9 1019.1 1019.7 Wt Flask+Water(D) 6126 6126 6125 6117.6 6126.1 6075.6 Wt Flask+Water+Sample(E) 6719.5 6714.7 6715.8 6707.4 6720.6 6671.4 SSD(B) 1005.4 995.4 1009.2 1007.2 1022.2 1022.2 Multiplier 1.00061 1.00038 1.00095 1.00095 1.00084 1.00084 Gmm 2.437 2.447 2.413 2.415 2.385 2.393 Avg Gmm 2.442 2.414 2.389 % Agg 0.945 0.940 0.935 Gse 2.647 2.660 2.640 2.641 2.625 2.636 Avg Gse 2.641 Table A-4. Drain-down Test for Georgia PEM-Granite %AC: 6.0 Mix Type: GPEM Sample: A B Mi, (g) Weight of mix before 1-hr aging 1274.2 1275.3 Pf, (g) (weight of paper disc + asphalt after draindown) 10.4 10.3 Pi, (g) (Initial Wt. Of paper Disc) 10.3 10.2 D (%Draindown) 0.01 0.01

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142 Table A-4. continued %AC: 6.0 Mix Type: GPEM Davg (Avg) 0.01 Drain-down test: Passes X Fails Table A-5. Film Thickness for Georgia PEM-Granite Sieve Percent Surface Area Factor SurfaceArea Size Passing ft.2/lb. m2/Kg ft2/lb. m2/Kg 11/2 in.(37.5mm) 100 1 in. (25.0mm) 100 3/4 in. (19.0mm) 100 1/2 in. (12.5mm) 90 3/8 in .( 9.5mm ) 60 2.0 0.41 No. 4 (4.75mm) 23 2 0.41 0.5 0.10 No. 8 (2.36mm) 9 4 0.82 0.4 0.08 No.16 (1.18mm) 6 8 1.64 0.5 0.10 No.30 ( 600um ) 4 14 2.87 0.6 0.12 No.50 ( 300um ) 3 30 6.14 0.9 0.19 No.100 (150um ) 2 60 12.29 1.1 0.23 No.200 ( 75um ) 1 160 32.77 1.7 0.35 hrs Total Surface Area 7.6 1.57 AC % = 6.0

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143 Table A-5. continued Film Thickness = [ 453.6 g per Pounds divided by % Aggregate ] [ 453.6 g per Pounds ] Surface area in square ft / lb 0.0 9290Sq. m per sq. ft. Sp. gr. of AC Or = 453.6 divided by 0.94 Minus 453.6 28.953 divided by 0.731 Or = Film Thickness 39.6 Micron Coating

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144 Effective Sp Gravof Agg% ACGmmGmbVMAVTMVFA2.6415.52.4421.93630.7420.7232.6062.4141.96130.2318.7837.866.52.3891.96730.3817.6841.82Optimum AC6% Mixing Temperature330 F Mineral Fiber0.4% of Total Mix Compaction Temperature325 F VMA30.1030.2030.3030.4030.5030.6030.7030.805.45.65.866.26.46.6% ACVMA VTM17.0018.0019.0020.0021.005.45.65.866.26.46.6% ACVTM VFA30.0032.0034.0036.0038.0040.0042.0044.0055.566.57% ACVMA Figure A-1. Final Mix Design for Georgia PEM-Granite

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APPENDIX B MAIN PROGRAMMING CODE OF PERFOMANCE TEST DATABSE (P.T.D.)

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APPENDIX C EFFECTIVE ASPHALT CONTENT CALCULATION FOR FILM THICKNESS DETERMINATION C-1 Water Absorption and Effective Asphalt Calculation 153

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154 Table C-1. Core-Lok Results calculation for Efffective asphalt content A BCDEFGHIJBag Weight (g ) Dry Sample Weight before Sealing (g ) Sealed Sample Weight in Water (g ) Dry Sample Weight After Water SubmerdioRatio B/ A Bag Volume Correction From TableTotal V olume (A + D) CVolume of Sample A /FVolume of Sample ( G-H ) Bulk Specific Gravity B/II50.74700.32328.8470092.710.7062421.971.8132350.0872.0001II50.74700.72312.54700.792.720.7062438.971.8132367.0871.9859Sam-ple ID Gmb2.00011.985 9 2 Gmb1.993 Table C-2. Minimum Film Thickness Effective Asphalt content Asphalt Absorption (%) Effective asphalt (ml) Film thickness (microns) 4.36 0.5 191.84 32.30 3.86 1 169.84 28.59 3.36 1.5 147.84 24.89 2.86 2 125.84 21.19 1.86 3 81.84 13.78 0.86 4 37.84 6.37

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APPENDIX D GEOMERTIC DETAILS OF FRACTURE TEST SPECIMEN AND MOLDS FOR ASPHALT MASTIC

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156 Figure D-1. Showing 3-D view of mold designed for preparing specimen for Asphalt Mastic

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157 Figure D-2. Base plate 3-D wire view showing position of groves and notch

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158 Figure D-3. Base plate geometry

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159 Figure D-4. Notch plate 3-D wire view.

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160 Figure D-5 Notch plate geometry

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APPENDIX E VOLUMETRIC PROPERTIES OF MIXTURES

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Table E-1. Volumetric Properties of all the Mixtures Volumetric Properties Denotation GPEM-Granite GPEM-Limestone I-295 PFC Granite Gradation (1) I-295 PFC Granite Gradation (2) FC-5 Granite FC-5 Limestone Bulk specific Gravity Gsb 2.626 2.442 2.729 2.716 2.623 2.444 Maximum Specific Gravity Gmm 2.414 2.298 2.485 2.491 2.441 2.336 Specific Gravity of Asphalt Gb 1.03 1.03 1.03 1.03 1.03 1.03 Total Asphalt Pb (%) 6.00 6.50 6.00 5.90 6.00 6.40 Effective Specific Gravity Gse 2.640 2.513 2.731 2.734 2.675 2.558 Asphalt Absorption Pab (%) 0.215 1.193 0.031 0.252 0.762 1.874 Effective Asphalt Content Peff (%) 5.785 5.307 5.969 5.648 5.238 4.526 Bulk Specific Gravity of Compacted Gravit y (Dimensional Analysis) Gmb 1.961 1.927 1.957 1.945 1.916 1.923 Voids in Mineral Aggregates VMA 30.23 28.3 32.69 32.76 32.67 29.64 Voids filled with Asphalt VFA 3.86 42.89 34.94 33.05 34.17 40.34 Voids in Total Mix VTM 18.78 16.16 21.27 21.93 21.51 17.68 Bulk Specific Gravity of Compacted Gravity (CoreLok) Gmb 1.992 162

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163 Table E-1. Continued. Volumetric Properties Denotation GPEMGranite GPEMLimestone I-295 PFC Granite Gradation (1) I-295 PFC Granite Gradation (2) FC-5 Granite FC-5 Limestone Water Absorption Wab (%) 3.38 Film Thickness (GDOT's method) (Microns) 38.08 34.76 27.12 25.77 19.96 24.12 Effective Film Thickness (Nukunya, 2001) (Microns) 54.58 50.07 33.12 31.65 23.95 32.19 Theoretical Film Thickness (Hveem, 1991) (Microns) 36.94 33.89 26.26 25.03 19.48 23.71

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APPENDIX F JOB MIX FORMULA Table F-1. Composition of Job Mix Formula of FC-5 Limestone Blend 45 48 7 JMF N umber of StockPiles S1A S1B Scrns 3/4" 19.0mm 100 100 100 100.0 1/2" 12.5mm 79 100 100 90.6 3/8" 9.5mm 36 92 100 67.4 N o. 4 4.75mm 7 26 100 22.6 N o. 8 2.36mm 3 7 68 9.5 N o. 16 1.18mm 3 3 67 7.5 N o. 30 600m 3 3 55 6.6 N o. 50 300m 3 2 35 4.8 N o. 100 150m 2 2 14 2.8 S I E V E S I Z E N o. 200 75m 1 1 3 1.1 Specific Gravity 2.4252 2.4509 2.527 2.444 Table F-2. Composition of Job Mix Formula of FC-5 Granite Blend 77 12 10 1 JMF N umber of Stockpiles #7 #789 Granite Granite Screens Lime 3/4" 19.0mm 100 100 100 100 100.0 1/2" 12.5mm 95 100 100 100 96.2 3/8" 9.5mm 64 92 100 100 71.3 N o. 4 4.75mm 11 20 97 100 21.6 N o. 8 2.36mm 3 5 68 100 10.7 N o. 16 1.18mm 2 3 43 100 7.2 N o. 30 600m 2 3 28 100 5.7 N o. 50 300m 2 3 18 100 4.7 N o. 100 150m 2 3 11 100 4.0 S I E V E S I Z E N o. 200 75m 1.1 2.5 8 100 2.9 Specific Gravity 2.627 2.633 2.58 2.69 2.624 164

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LIST OF REFERENCES Cooley, L. A., B.D. Prowell, M. R. Hainin, M. S. Buchanan, J. Harrington. Bulk Specific gravity Round-Robin using the Corelok Vacuum Sealing Device, National center of Asphalt Technology, NCAT Report 02-11, November 2002. Georgia Department of Transportation. Sample Testing and Inspection. http://tomcat2.dot.state.ga.us/thesource/sti/index.html GDT Table of Contents, October 27, 2004. Goode, J.F., L.A. Lufsey. Voids, Permeability, Film Thickness VS. Asphalt Hardening. Proceedings of AAPT, Vol. 35, pp 420-463, 1965. InstroTek. CoreLok Manual. http://www.instrotek.com/download.htm Raleigh, NC 27617 USA, November 10, 2003. Kandhal, P. S., R. B. Mallick. Open Graded Asphalt Friction Course: State of The Practice, NCAT Report No. 98-7, May 1998. Method of Test for Determining Optimum Asphalt Content for Open-Graded Bituminous Paving Mixtures. Georgia Department of Transportation, GDT-114, June 1989, Revised May 28, 1996. Mindess, S., S. Diamond. A Preliminary SEM Study of Crack Propagation in Mortar. In Journal of the Cement and Concrete Research, Vol. 10,pp 509-519,April 21 1980. Nukanya, B., R. Roque, M. Tia, B. Birgisson. Evaluation of VMA and other Volumetric Properties as Criteria for the Design and Acceptance of Superpave Mixtures. Journal of the Association of Asphalt Paving Technologists, Vol. 70, pp 38-69, 2001. Roque, R., W.G. Butlar. Development and Evaluation of the Strategic Highway Research Program Measurement and Analysis System for Indirect Tensile Testing at Low temperatures. Transportation Research Record 1454, TRB, National Research Council, Washington, D.C., 1994. Roque, R., Z. Zhang, B. Shankar. Determination of Crack Growth Rate Parameters using the Superpave IDT. Journal of the Association of Asphalt Paving Technologists, Vol.68, 1999. Subramanian, K. N., P.F. Becher, C.C. Wu. Paper presented at the 80th Annual Meeting of the American Ceramic Society, Detroit, May 1978. 165

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166 Vardhan A. Evaluation of Open-Graded And Bonded Friction Course For Florida, Masters Thesis, University of Florida, August 2004. Vavrik, W.R., S.H. Carpenter. Calculating Air Voids at Specified Number of Gyrations in Superpave Gyratory Compactor. In Transportation Research Record 1630, TRB, National Research Council, Washington, D.C., 1998. Watson, D., A. Johnson, D. Jared. Georgia Department of Transportations Progress in Open Graded Friction Course Development. Transportation Research Record 1616,TRB, National research Council, Washington, D.C., 1998.

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BIOGRAPHICAL SKETCH Lokendra Jaiswal was born on August 27, 1981, in the city of Indore, India. He received his Diploma in Civil Engineering from Maharashtra State Board of Technical Education, Nagpur, India, May 1999. He received his bachelors degree in civil engineering from University of Pune, Pune, in May 2002. After his undergraduate studies, He came to the University of Florida to pursue a Master of Engineering degree. He plans to work in a Structural engineering consultancy firm in Florida after he graduates with his M.E. degree. 167