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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Mixing and Compaction Temperatures of Asphalt Binders in Hot-Mix Asphalt. Washington, DC: The National Academies Press. doi: 10.17226/14367.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Mixing and Compaction Temperatures of Asphalt Binders in Hot-Mix Asphalt. Washington, DC: The National Academies Press. doi: 10.17226/14367.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Mixing and Compaction Temperatures of Asphalt Binders in Hot-Mix Asphalt. Washington, DC: The National Academies Press. doi: 10.17226/14367.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Mixing and Compaction Temperatures of Asphalt Binders in Hot-Mix Asphalt. Washington, DC: The National Academies Press. doi: 10.17226/14367.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Mixing and Compaction Temperatures of Asphalt Binders in Hot-Mix Asphalt. Washington, DC: The National Academies Press. doi: 10.17226/14367.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Mixing and Compaction Temperatures of Asphalt Binders in Hot-Mix Asphalt. Washington, DC: The National Academies Press. doi: 10.17226/14367.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2010. Mixing and Compaction Temperatures of Asphalt Binders in Hot-Mix Asphalt. Washington, DC: The National Academies Press. doi: 10.17226/14367.
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TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2010 www.TRB.org N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP REPORT 648 Subscriber Categories Materials Mixing and Compaction Temperatures of Asphalt Binders in Hot-Mix Asphalt Randy C. West Donald E. Watson Pamela A. Turner NATIONAL CENTER FOR ASPHALT TECHNOLOGY Auburn, AL John R. Casola MALVERN INSTRUMENTS INC. Westborough, MA Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Board’s recognized objectivity and understanding of modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or duplicate other highway research programs. Published reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at: http://www.national-academies.org/trb/bookstore Printed in the United States of America NCHRP REPORT 648 Project 9-39 ISSN 0077-5614 ISBN 978-0-309-11825-5 Library of Congress Control Number 2010923478 © 2010 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION 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, or Transit Development Corporation 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. NOTICE The project that is the subject of this report was a part of the National Cooperative Highway Research Program conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. Such approval reflects the Governing Board’s judgment that the program concerned is of national importance and appropriate with respect to both the purposes and resources of the National Research Council. The members of the technical committee selected to monitor this project and to review this report were chosen for recognized scholarly competence and with due consideration for the balance of disciplines appropriate to the project. The opinions and conclusions expressed or implied are those of the research agency that performed the research, and, while they have been accepted as appropriate by the technical committee, they are not necessarily those of the Transportation Research Board, the National Research Council, the American Association of State Highway and Transportation Officials, or the Federal Highway Administration, U.S. Department of Transportation. Each report is reviewed and accepted for publication by the technical committee according to procedures established and monitored by the Transportation Research Board Executive Committee and the Governing Board of the National Research Council. The Transportation Research Board of the National Academies, the National Research Council, the Federal Highway Administration, the American Association of State Highway and Transportation Officials, and the individual states participating in the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of this report.

CRP STAFF FOR NCHRP REPORT 648 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Edward T. Harrigan, Senior Program Officer Melanie Adcock, Senior Program Assistant Eileen P. Delaney, Director of Publications Margaret B. Hagood, Editor Andréa Briere, Editor NCHRP PROJECT 09-39 PANEL Field of Materials and Construction—Area of Bituminous Materials Rita B. Leahy, Asphalt Pavement Association of California, Sacramento, CA (Chair) John H. Tenison, AMEC Earth & Environmental, Albuquerque, NM Paul J. Hoelscher, Texas DOT, Abilene, TX Gayle N. King, GHK, Inc., The Woodlands, TX Michael W. Longshaw, Kansas DOT, El Dorado, KS Louay N. Mohammad, Louisiana State University, Baton Rouge, LA Allen H. Myers, Kentucky Transportation Cabinet, Frankfort, KY Nelio J. Rodrigues, Connecticut DOT, Rocky Hill, CT John D’Angelo, FHWA Liaison Nelson H. Gibson, FHWA Liaison Frederick Hejl, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 9-39 by the National Center for Asphalt Technology, Auburn University. Randy C. West, Director, was the principal investigator and Donald E. Watson, Lead Research Engineer at the National Center for Asphalt Technology, was the co-principal investigator. John Casola, Product Sales Manager at Malvern Instruments, and Pamela Turner, Assistant Research Engineer at the National Center for Asphalt Technology, were key contributors to the research and preparation of this report. The authors thank Fred Mazzeo of Malvern Instruments for providing rheological testing and analysis and Saeed Maghsoodloo, Auburn University, for experimental design and statistical analysis. The authors thank Jason Moore and all of the staff of the National Center for Asphalt Technology who worked on this project. The authors thank the Federal Highway Administration Turner- Fairbank Highway Research Center for binder testing and the asphalt binder suppliers who provided mate- rials and information for this project. C O O P E R A T I V E R E S E A R C H P R O G R A M S

This report identifies improved test methods for determining laboratory mixing and compaction temperatures of modified and unmodified asphalt binders. The report will be of immediate interest to materials engineers in state highway agencies and the hot-mix asphalt (HMA) construction industry. The Asphalt Institute (AI) procedure for determining mixing and compaction tempera- tures of asphalt binders was developed for penetration- and viscosity-graded asphalt cements used in the United States until the 1990s. Since that time, the use of modified, performance-graded asphalt binders in HMA paving has increased significantly, especially on high-volume traffic routes. The AI procedure often requires heating of modified binders to unrealistically high temperatures that can potentially damage the asphalt binder. To over- come this problem, highway agencies usually rely on the modifier suppliers to recommend mixing and compaction temperatures, a circumstance that can produce mixed results. The objective of this research was to identify or develop a simple, rapid, and accurate lab- oratory procedure—suitable for routine use—for determining the mixing and compaction temperatures of both unmodified and modified asphalt binder. The research was performed by the National Center for Asphalt Technology, Auburn University, Auburn, Alabama with the support of Malvern Instruments Inc., Westborough, Massachusetts. In the course of the research, the project team evaluated existing and emerging methods to determine temperatures that will provide satisfactory aggregate coating during laboratory mix- ing and appropriate laboratory specimen compaction without degrading the asphalt binder and identified two improved, equally effective test methods. These tests, termed (1) the phase angle method and (2) the steady shear flow viscosity (SSFV) method, provide reasonable, consistent mixing and compaction temperatures that correlate well with the results of HMA coating, workability, and compactability tests for both binder types. The phase angle and SSFV mea- surements are made with the dynamic shear rheometer (DSR), already widely used in asphalt laboratories for measuring binder stiffnesses over a range of temperatures and frequencies. This report includes four appendices as follows: • Appendix A: Responses of Survey on Agency Specifications Regarding Mixing and Com- paction Temperatures; • Appendix B: Mix Design Data for Base Mix and Other Compaction Experiment Mixes; • Appendix C: Draft AASHTO Standard for Steady Shear Flow and Phase Angle Methods; and • Appendix D: Statistical Analyses of the Steady Shear Flow and Phase Angle Methods. The draft standard methods of test are under consideration for possible adoption by the AASHTO Highway Subcommittee on Materials. F O R E W O R D By Edward Harrigan Staff Officer Transportation Research Board

C O N T E N T S 1 Summary 5 Chapter 1 Background 5 Introduction 5 Literature Search 5 A Note on Units of Viscosity 6 Background on the Development of Mixing and Compaction Temperature Criteria 8 Effect of Temperature on Degradation of Asphalt Binders 9 Mixing and Compaction Temperatures for Modified Asphalt Binders 10 Survey of Current Practices for Determining Mixing and Compaction Temperatures 13 Recent Research on Proposed New Methods for Determining Mixing and Compaction Temperatures 13 Zero Shear Viscosity 14 Extrapolated High Shear Rate Viscosity 14 Steady Shear Flow 14 Shear Rate Dependency 15 Extensional Viscosity 15 Equivalent Mixture Properties 15 Workability 16 Shear Rates During Mixing and Compaction 19 Summary of Key Findings from the Literature Review 20 Chapter 2 Research Approach 20 Experimental Plan 20 Approach 20 Overview of the Experimental Research Plan 22 Materials 22 Organization of the Test Plan 23 Part 1: Binder Tests 23 Part 2: Mixture Tests 24 Description of Tests 24 Binder Tests 30 Mixture Tests 31 Summary of Research Plan 33 Chapter 3 Findings and Applications 33 Experimental Results 33 Binder Testing 33 Binder Grading 33 High Shear Rate Viscosity Method 33 Steady Shear Flow Method

33 Phase Angle Method 34 SEP Tests 37 Results of Re-Graded Binders 37 MSCR Tests 37 Analysis of Binder Degradation 43 Mixture Testing 43 Mixture Coating Tests 45 Mixture Coating Tests with Incompletely Dried Aggregate 46 Workability Tests 47 Compaction Tests 53 Indirect Tensile Creep Compliance and Strength 59 Correlation of Mixing and Compaction Temperatures 66 Comparison of SSF and Phase Angle Methods 68 Validation Experiment Results and Analysis 72 Chapter 4 Conclusions and Recommendations 72 Summary of Key Findings 73 Recommendation of a New Method for Determining Mixing and Compaction Temperatures 73 Recommendations for Further Work 73 Independent Validation 74 Refinement of the SSF and Phase Angle Methods 74 Interlaboratory Studies 74 Training 76 References A-1 Appendix A Responses of Survey on Agency Specifications Regarding Mixing and Compaction Temperatures B-1 Appendix B Mix Design Data for Base Mix and Other Compaction Experiment Mixes C-1 Appendix C Draft AASHTO Standard for Steady Shear Flow and Phase Angle Methods D-1 Appendix D Statistical Analyses of the Steady Shear Flow and Phase Angle Methods

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TRB’s National Cooperative Highway Research Program (NCHRP) Report 648: Mixing and Compaction Temperatures of Asphalt Binders in Hot-Mix Asphalt explores enhanced test methods for determining laboratory mixing and compaction temperatures of modified and unmodified asphalt binders.

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