Short-Term Laboratory Conditioning of Asphalt Mixtures (2015)

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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 815 Short-Term Laboratory Conditioning of Asphalt Mixtures David Newcomb Amy Epps Martin Fan Yin Edith Arambula Eun Sug Park Arif Chowdhury Texas a&M TransporTaTion insTiTuTe College Station, TX Ray Brown Carolina Rodezno Nam Tran naTional CenTer for asphalT TeChnology Auburn, AL Erdem Coleri David Jones John T. Harvey James M. Signore universiTy of California paveMenT researCh CenTer Berkeley, CA Subscriber Categories Construction • Materials • Pavements TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2015 www.TRB.org 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 is the most effective way to solve 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 results in increasingly complex problems of wide inter- est to highway authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniques—the National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRB’s recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRB’s relationship to the Academies is an insurance of objectivity; and TRB maintains a full-time staff of specialists in high- way transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs identified by chief administrators and other staff of the highway and transporta- tion departments and by committees of AASHTO. Topics of the highest merit are selected by the AASHTO Standing Committee on Research (SCOR), and each year SCOR’s recommendations are proposed to the AASHTO Board of Directors and the Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and surveillance of research contracts are the responsibilities of the Acad- emies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving 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 by going to http://www.national-academies.org and then searching for TRB Printed in the United States of America NCHRP REPORT 815 Project 09-52 ISSN 0077-5614 ISBN 978-0-309-37489-7 Library of Congress Control Number 2015954187 © 2015 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, FRA, FTA, Office of the Assistant Secretary for Research and Technology, PHMSA, or TDC 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 report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the National Academies of Sciences, Engineering, and Medicine. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; or the program sponsors. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; and the sponsors of 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 the report.

The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Ralph J. Cicerone is president. The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. C. D. Mote, Jr., is president. The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.national-academies.org. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to increase the benefits that transportation contributes to society by providing leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Board’s varied activities annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.

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 AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 9-52 by the Texas A&M Transportation Institute, a member of The Texas A&M University System, with the Texas A&M Univer- sity Research Foundation serving as fiscal administrator. Dr. David Newcomb, senior research engineer at the Texas A&M Transporta- tion Institute, was the project director and principal investigator. Other authors of this report are Dr. Amy Epps Martin, Mr. Fan Yin, Dr. Edith Arambula, Dr. Eun Sug Park, and Mr. Arif Chowdhury from the Texas A&M Transportation Institute; Dr. Ray Brown, Dr. Carolina Rodezno, and Dr. Nam Tran from the National Cen- ter for Asphalt Technology; and Dr. Erdem Coleri, Dr. David Jones, Dr. John Harvey, and Dr. James M. Signore from the University of California Pavement Research Center. The Western Research Institute and the University of Nevada Reno were very generous in allowing the research team to share their field sites and for providing critical information to the research team. A sub- stantial debt of gratitude is owed the state departments of transporta- CRP STAFF FOR NCHRP REPORT 815 Christopher W. Jenks, Director, Cooperative Research Programs Christopher Hedges, Manager, National Cooperative Highway Research Program Edward T. Harrigan, Senior Program Officer Anthony Avery, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Senior Editor NCHRP PROJECT 09-52 PANEL Field of Materials and Construction—Area of Bituminous Materials Frank Fee, Frank Fee, LLC, Media, PA (Chair) Cathrina Barros, Caltrans, Sacramento, CA Pete Capon, Rieth-Riley Construction, Inc., Goshen, IN Timothy R. Clyne, Minnesota DOT, Roseville, MN Joseph DeVol, Washington State DOT, Tumwater, WA John E. Grieco, Massachusetts DOT, Boston, MA Scott A. Schram, Iowa DOT, Ames, IA Annette G. Smith, PQ Corporation, Malvern, PA Vivek Tandon, University of Texas at El Paso, El Paso, TX James A. Williams III, Mississippi DOT, Brandon, MS Jack Youtcheff, FHWA Liaison Matthew Corrigan, Federal Highway Administration Liaison Kent R. Hansen, National Asphalt Pavement Association Liaison tion of Texas, New Mexico, Wyoming, Iowa, South Dakota, Florida, Indiana, and Connecticut for their willingness to provide test sections and support. The following contractors allowed the research team access to their jobs and provided a great deal of assistance in achiev- ing the goals of the project: J.H. Hamilton Construction Co. (New Mexico); Tilcon, a division of Oldcastle Materials, Inc. (Connecticut); Rieth-Riley Construction Co. (Indiana); Reese-Albert Construction Co. (Odessa, Texas); Manatts, Inc. (Iowa); Commercial Asphalt Co. (South Dakota); McGarvin-Moberly Construction Co. (Wyoming); Duval Asphalt (Florida); and Ramming Paving Co., a division of Summit Construction Co. (Austin, Texas). The authors would like to acknowledge Dr. Jon Epps from the Texas A&M Transportation Institute and Mr. Chuck Paugh from the Federal Highway Administration for their contributions to this study. The assistance of Rick Canatella, Stephen Johnson, Daniel Furdock, Guillermo Gomez Salas, Adam Joel Taylor, Grant Julian, and Eyoab Zegeye in laboratory-related activities is greatly appreciated.

F O R E W O R D By Edward T. Harrigan Staff Officer Transportation Research Board This report presents proposed changes to AASHTO R 30, Mixture Conditioning of Hot Mix Asphalt (HMA), and a proposed AASHTO practice for conducting plant aging studies. Thus, the report will be of immediate interest to materials engineers in state highway agen- cies and the construction industry with responsibility for design and production of hot and warm mix asphalt. Laboratory conditioning of asphalt mixtures during the mix design process to simulate their short-term aging influences the selection of the optimum asphalt content. In addition, conditioning affects the mixture and binder stiffness, deformation, and strength evaluated with fundamental characterization tests to assess mixture performance. The conditioning process must also address the rapidly increasing use of warm mix asphalt (WMA), for which production temperatures are substantially lowered from those required for hot mix asphalt (HMA). Past research using limited field data found that 2 hours of oven conditioning at the anticipated compaction temperature reasonably reproduced the binder absorption and stiffening that occurs during construction for both WMA and HMA. As would be expected, the binder in a WMA mixture conditioned 2 hours at its lower compaction temperature is less stiff than that in a similarly conditioned HMA mixture. Such reduced aging is signifi- cant in interpreting WMA performance test results compared to those of HMA for both laboratory- and field-produced mixtures. The current standard conditioning procedure, AASHTO R 30, Mixture Conditioning of Hot Mix Asphalt (HMA), was developed over two decades ago and was reviewed to determine whether it required updating to address today’s asphalt materials and mix production processes. The objective of this research was to develop procedures and associated criteria for short- term laboratory conditioning of asphalt mixtures—both HMA and WMA—for mix design and performance testing to simulate the effects of (1) plant mixing and processing to the point of loading in the transport truck and (2) an initial period of field performance. The research was performed by the Texas A&M Transportation Institute, Texas A&M University, College Station, Texas, in conjunction with the National Center for Asphalt Technology, Auburn, Alabama, and the Pavement Research Center, University of California, Berkeley, California. The short-term aging of asphalt mixtures was investigated through a series of statisti- cally designed laboratory and field experiments. The research confirmed a key finding of NCHRP Project 9-49, “Performance of WMA Technologies: Stage I—Moisture Susceptibil- ity” (see NCHRP Report 763), that the effects of plant mixing and processing to the point of loading in the transport truck are well simulated by 2 hours of oven aging at either 275°F (135°C) for HMA or 240°F (116°C) for WMA. Further, the research found that an initial field performance period of 1 to 2 years (depending on the specific project climate) is well

simulated by 5 days of oven aging at 85°C (185°F). This latter finding calls into question the original recommendation from research conducted by the Strategic Highway Research Program, i.e., that these conditions were equivalent to 5 to 10 years of field aging. Using resilient modulus as a metric, the field experiment found that the stiffness of WMA was initially lower than that of HMA for the majority of the field projects, but it caught up to HMA stiffness in about 17 months in warmer climates and 30 months in colder climates. The report recommends using cumulative degree-days (heating, base 32°F[0°C]) rather than time in service to accurately quantify field aging and account for differences in con- struction dates and climates for various field sites. Practical outcomes of the project are presented as (1) proposed changes to AASHTO R 30 and (2) a proposed AASHTO practice to measure the effects of asphalt plant mixing and processing on binder absorption by aggregate and asphalt mixture characteristics in the field. This report fully documents the research and includes seven appendices.

C O N T E N T S 1 Summary 5 Chapter 1 Background 6 Project Objectives and Scope 6 Previous Research on Short-Term Conditioning 9 Previous Research on Long-Term Aging 13 Chapter 2 Research Approach 13 Experimental Design 13 Phase I Experiment 13 Phase II Experiment 16 Laboratory Tests 16 Resilient Modulus 16 Dynamic Modulus 17 Hamburg Wheel-Tracking Test 18 Dynamic Shear Rheometer 20 Bending Beam Rheometer 20 Fourier Transform Infrared Spectroscopy 21 Field Sites 23 Specimen Fabrication 25 Chapter 3 Findings and Applications 25 Phase I 25 Mixture Volumetrics 25 Simulation of Plant Aging 31 Identification of Factors Affecting the Performance of Short-Term Aged Asphalt Mixtures 38 Phase II 38 Quantification of Field Aging 40 Correlation of Field Aging with Laboratory LTOA Protocols 43 Identification of Factors With Significant Effects on Mixture Aging Characteristics 50 Chapter 4 Conclusions and Suggested Research 50 Phase I Experiment 50 Simulation of Plant Aging 51 Factor Analysis 51 Phase II Experiment 51 Quantification of Field Aging and Correlation to Laboratory LTOA Protocols 52 Factor Analysis 52 Suggested Research

54 References 56 Abbreviations, Acronyms, and Symbols A-1 Appendix A Construction Reports B-1 Appendix B Effect of Plant Type on Binder Aging C-1 Appendix C Preliminary Laboratory Experiment D-1 Appendix D Round Robin Study E-1 Appendix E Statistical Analysis F-1 Appendix F Proposed AASHTO Recommended Practice for Conducting Plant Aging Studies G-1 Appendix G Recommended Changes to Standard Practice for Mixture Conditioning of Hot Mix Asphalt (HMA)