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ACKNOWLEDGMENT This work was sponsored by the American Association of State Highway and Transportation Officials (AASHTO), in cooperation with the Federal Highway Administration, and was conducted in the National Cooperative Highway Research Program (NCHRP), which is administered by the Transportation Research Board (TRB) of the National Academies. COPYRIGHT PERMISSION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, Transit Development Corporation, or AOC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. DISCLAIMER The opinion and conclusions expressed or implied in the report are those of the research agency. They are not necessarily those of the TRB, the National Research Council, AASHTO, or the U.S. Government. This report has not been edited by TRB.
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TABLE OF CONTENTS LIST OF TABLES ....................................................................................................................................IV LIST OF FIGURES ................................................................................................................................... V ACKNOWLEDGMENTS ........................................................................................................................VI ABSTRACT............................................................................................................................................. VII EXECUTIVE SUMMARY ........................................................................................................................ 8 CHAPTER 1- INTRODUCTION AND RESEARCH APPROACH ................................................... 10 1.1 Introduction............................................................................................................................ 10 1.1.1 Problem Statements................................................................................................... 10 1.1.1.1 Interlaboratory Study (ILS) Problem Statement........................................ 10 1.1.1.2 Aging Time Study Problem Statement...................................................... 10 1.1.2 Research Objectives.................................................................................................. 11 1.2 Scope of Study ....................................................................................................................... 11 CHAPTER 2- MATERIALS SELECTION AND MIX DESIGN ........................................................ 12 2.1 Materials Selection................................................................................................................. 12 2.1.1 Source 1 Aggregate................................................................................................... 12 2.1.2 Source 2 Aggregate................................................................................................... 12 2.1.3 Asphalt Binder .......................................................................................................... 13 2.2 Mix Designs ........................................................................................................................... 13 CHAPTER 3- INTERLABORATORY STUDY EXPERIMENTAL PLAN....................................... 14 3.1 Overall Plan............................................................................................................................ 14 3.2 Selection of Laboratories ....................................................................................................... 14 3.3 Test Samples and Test Protocols............................................................................................ 15 3.3.1 Sample Preparation ................................................................................................... 15 3.3.2 Test Protocols and Instruction and Data Forms for Participants............................... 16 CHAPTER 4- INTERLABORATORY TEST RESULTS AND ANALYSIS ..................................... 17 4.1 Test Data ................................................................................................................................ 17 4.2 Method of Analysis................................................................................................................ 17 4.3 Theoretical Maximum Specific Gravity, Gmm........................................................................ 17 4.3.1 Introduction...............................................................................................................17 4.3.2 Precision Estimates ................................................................................................... 18 4.3.3 Tests for Significance................................................................................................ 18 4.3.4 Comparison of Precision Estimates Using Mixtures with Absorptive Aggregates vs. Mixtures with Non-Absorptive Aggregates .............................................................. 19 4.3.5 Precision Statements ................................................................................................. 19 4.4 Bulk Specific Gravity, Gmb .................................................................................................... 19 4.4.1 Introduction...............................................................................................................19
ii 4.4.2 Precision Estimates ................................................................................................... 20 4.4.2.1 T166 Test Data .......................................................................................... 20 4.4.2.2 D6752 Test Data........................................................................................ 20 4.4.3 Tests for Significance................................................................................................ 20 4.4.4 Comparison of Precision Estimates Using Mixtures with Absorptive Aggregates vs. Mixtures with Non-Absorptive Aggregates .............................................................. 21 4.4.5 Precision Statements ................................................................................................. 21 4.4.5.1 T 166 ......................................................................................................... 21 4.4.5.2 D6752 ........................................................................................................ 22 4.5 Relative Density at Ni and Nd................................................................................................. 22 4.5.1 Introduction...............................................................................................................22 4.5.2 Precision Estimates ................................................................................................... 22 4.5.3 Tests for Significance................................................................................................ 23 4.5.4 Comparison of Precision Estimates Using Mixtures with Absorptive Aggregates vs. Mixtures with Non-Absorptive Aggregates .............................................................. 23 4.5.5 Precision Statement...................................................................................................24 CHAPTER 5- AGING TIME STUDY .................................................................................................... 45 5.1 Experimental Design.............................................................................................................. 45 5.2 Sample Preparation and Testing.............................................................................................45 5.3 Analysis of Selective Volumetric Properties ......................................................................... 45 5.3.1 Theoretical Maximum Specific Gravity (ASTM D2041) ......................................... 45 5.3.2 Bulk Specific Gravity AASHTO T166 ..................................................................... 46 5.3.3 Percent Air Voids of Hot Mix Asphalt ...................................................................... 46 5.3.4 Percent Absorbed Binder Content............................................................................. 47 5.3.5 Component Diagram of Asphalt Mixtures................................................................ 48 5.3.6 Asphalt Binder Film Thickness................................................................................. 48 CHAPTER 6- CONCLUSIONS AND RECOMMENDATIONS ......................................................... 57 6.1 General ................................................................................................................................... 57 6.2 Conclusions and Recommendations Related to Interlaboratory Study .................................. 58 6.2.1 ASTM D2041............................................................................................................ 58 6.2.1.1 Conclusions ............................................................................................... 58 6.2.1.2 Recommendations ..................................................................................... 58 6.2.2 AASHTO T166......................................................................................................... 58 6.2.2.1 Conclusions ............................................................................................... 58 6.2.2.2 Recommendations ..................................................................................... 58 6.2.3 ASTM D6752 Results...............................................................................................58 6.2.3.1 Conclusions ............................................................................................... 58 6.2.3.2 Recommendations ..................................................................................... 59 6.2.4 AASHTO T312......................................................................................................... 59 6.2.4.1 Conclusions ............................................................................................... 59 6.2.4.2 Recommendations ..................................................................................... 59 6.3 Conclusions and Recommendations Related to Aging Time Study....................................... 60 6.3.1.1 Conclusions ............................................................................................... 60 6.3.1.2 Recommendations ..................................................................................... 60 REFERENCES.......................................................................................................................................... 62
iii APPENDIX A............................................................................................................................................ 63 APPENDIX B ............................................................................................................................................ 65 APPENDIX C............................................................................................................................................ 74 APPENDIX D............................................................................................................................................ 76 APPENDIX E ............................................................................................................................................ 77 APPENDIX F ............................................................................................................................................ 78
iv LIST OF TABLES Table 3-1- ILS sample production schedule ........................................................................................... 15 Table 3-2- Test properties determined in the ILS study ....................................................................... 16 Table 4-1- Volumetric properties of three replicates of Source 1 mixtures in the ILS study ............ 25 Table 4-2- Volumetric properties of three replicates of Source 2 mixtures in the ILS Study............ 26 Table 4-3- Precision estimates of volumetric properties of the four mixtures .................................... 27 Table 4-4- Combined statistics of volumetric properties of Source 1 and Source 2 mixtures ........... 28 Table 4-5- Results of t-test on bias of the volumetric properties of 9.5-mm and 19-mm mixtures ... 28 Table 4-6- Results of t-test on bias of the volumetric properties measured according to T166 and D6752 ....................................................................................................................................... 28 Table 4-7- Results of F test for comparison of precision estimates for volumetric properties of 9.5- mm and 19-mm mixtures ....................................................................................................... 29 Table 4-8- Results of F test for comparison of the precision estimates of T166 and D6752............... 29 Table 4-9- Precision estimates of selective volumetric properties using mixtures with absorptive aggregates and mixtures with non-absorptive aggregates; âFinerâ mixtures represent 9.5-mm in Phase 4 and 12.0-mm in Phase 1 studies and âcoarserâ mixtures represent 19- mm mixtures ........................................................................................................................... 30 Table 4-10- Results of F test for comparing precision estimates of volumetric properties of mixtures with absorptive aggregates (Phase 4) and mixtures with non-absorptive aggregates (Phase 1) ............................................................................................................... 30 Table 5-1- Average of the measured volumetric properties in the aging time study .......................... 50 Table 5-2- Summary of results of ANOVA on Gmm values in the aging time study............................ 51 Table 5-3- Summary of results of ANOVA on Gmb values in the aging time study............................. 51 Table 5-4- Summary of results of ANOVA on air void values in the aging time study ...................... 51
v LIST OF FIGURES Figure 3-1- Box samples for participating laboratories......................................................................... 16 Figure 4-1- Box plots of maximum specific gravity (Gmm) -D2041 ....................................................... 31 Figure 4-2- h and k consistency statistics of maximum specific gravity (Gmm)-D2041 ....................... 32 Figure 4-3- Box plots of bulk specific gravity (Gmb)-T166..................................................................... 33 Figure 4-4- h and k consistency statistics of bulk specific gravity (Gmb)-T166.................................... 34 Figure 4-5- Box plots of bulk specific gravity (Gmb)-D6752 .................................................................. 35 Figure 4-6- h and k consistency statistics of bulk specific gravity (Gmb)-D6752 ................................. 36 Figure 4-7- Box plots of relative density at Nin computed using T 166 Gmb values-T312 ................... 37 Figure 4-8- h and k consistency statistics of relative density at Nin using T166 Gmb-T312................. 38 Figure 4-9 - Box plots of relative density at Nd computed uisng T 166 Gmb values-T312 ................... 39 Figure 4-10- h and k consistency statistics of relative density at Nd using T166 Gmb-T312................ 40 Figure 4-11- Box plots of relative density at Nin computed uisng D6752 Gmb values-T312 ................ 41 Figure 4-12- h and k consistency statistics of relative density at Nin using D6752 Gmb-T312............. 42 Figure 4-13- Box plots of relative density at Nd computed uisng D6752 Gmb values-T312................. 43 Figure 4-14- h and k consistency statistics of relative density at Nd using D6752 Gmb-T312 ............. 44 Figure 5-1- Average Gmm values of the four mixtures at various aging times ..................................... 52 Figure 5-2- Average Gmb values of the four mixtures at various aging times...................................... 52 Figure 5-3- Average % air void values of the four mixtures at various aging times .......................... 53 Figure 5-4- Average difference in % air voids of 2-hour and consequent aging times....................... 53 Figure 5-5- Average of % absorbed asphalt of the four mixtures at various aging times.................. 54 Figure 5-6- Average difference in % absorbed asphalt of 2-hour and consequent aging times ........ 54 Figure 5-7- The volumetric component diagram of the S1-9.5-mm mixture at various aging times 55 Figure 5-8- The volumetric component diagram of the S1-19-mm mixture at various aging times . 55 Figure 5-9- The volumetric component diagram of the S2-9.5-mm mixture at various aging times 56 Figure 5-10- The volumetric component diagram of the S2-19-mm mixture at various aging times56 Figure 5-11- Asphalt film thickness in the four mixtures at various aging times ............................... 57
