Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments (2017)

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2017 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 RESEARCH REPORT 837 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments Y. Richard Kim Javon Adams Cassie Castorena Mohammad Ilias Jeong Hyuk Im North CaroliNa State UNiverSity Raleigh, NC Hussain Bahia Preeda Chaturabong Andrew Hanz Petrina T. Johannes UNiverSity of WiSCoNSiN-MadiSoN Madison, WI Subscriber Categories Maintenance and Preservation • Materials 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. 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Published research 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 RESEARCH REPORT 837 Project 09-50 ISSN 0077-5614 ISBN 978-0-309-44616-7 Library of Congress Control Number 2017930268 © 2017 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 research 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. 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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. Marcia McNutt 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 committees, task forces, and panels 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 CRP STAFF FOR NCHRP RESEARCH REPORT 837 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Amir N. Hanna, Senior Program Officer Natasha R. Donawa, Senior Program Assistant Eileen P. Delaney, Director of Publications Ellen M. Chafee, Senior Editor NCHRP PROJECT 09-50 PANEL Field of Materials and Construction—Area of Bituminous Materials Kee Y. Foo, California DOT, Sacramento, CA (Chair) Amit Bhasin, University of Texas at Austin, Austin, TX Steven Brakeall, Maryland State Highway Administration, Hanover, MD Shongtao Dai, Minnesota DOT, Maplewood, MN Stacey D. Diefenderfer, Virginia Transportation Research Council, Charlottesville, VA Gary L. Hoffman, Pennsylvania Asphalt Pavement Association, Harrisburg, PA Bryce P. Simons, Edgewood, NM (formerly with New Mexico DOT) Jack Youtcheff, FHWA Liaison Nelson H. Gibson, TRB Liaison

This research report presents recommended emulsion performance grade (EPG) spec- ifications for asphalt emulsions used in three pavement preservation surface treatments (PSTs): chip seal, microsurfacing, and spray seals. These EPG specifications are climate- driven and applicable to traffic loads that are anticipated during the service life of each PST. The report also presents recommended test protocols for evaluating some of the properties of binders for which test methods are not readily available. The information contained in the report will guide materials and maintenance engineers in evaluating, selecting, and specifying binders for use in PSTs that will provide acceptable performance and service life. The information contained in the report will be of immediate interest to materials and maintenance engineers and others involved in specifying and evaluating materials intended for use in PSTs. The properties of asphaltic binders used in PSTs are very important to the performance of the treatment in which they are used. However, the asphaltic binders used in such treat- ments are often selected based on availability and other factors that are not necessarily related to the performance of the final product. Often distress, such as raveling, bleeding, rutting, and cracking of these treatments, can be traced directly to improper selection and use of the emulsion used in these PSTs. Clearly, proper emulsion selection is necessary for attaining desired performance. EPG specifications that specify quality in terms related to long-term performance will help in the selection of the proper emulsion for a specific application. Although such speci- fications have been developed for the constituents of hot-mix asphalt mixtures used in pavements, EPG specifications are not readily available for binders used in PSTs. Therefore, research was needed to (1) evaluate existing binder tests and, if necessary, identify new tests that relate to performance and (2) develop EPG specifications that provide a direct relation- ship between key quality characteristics of asphaltic binders and PST performance. Under NCHRP Project 09-50, “Performance-Related Specifications for Asphaltic Binders Used in Preservation Surface Treatments,” North Carolina State University worked with the objective of recommending EPG specifications for the selection of asphalt emulsion used in PSTs. To accomplish this objective, the researchers reviewed available information to identify the types and causes of critical distresses that relate to asphalt binder performance for each type of PST and investigated binder and mixture test methods that address these distress types. A framework for developing EPG specifications for binders used in chip seal, microsurfacing, and spray seal applications was then proposed and validated in a short- term field experiment; proposed specifications for these emulsions were then prepared (included as Attachment 1). Also, test protocols for evaluating some of the properties of F O R E W O R D By Amir N. Hanna Staff Officer Transportation Research Board

binders for which test methods are not readily available and proposed changes to an existing test method were prepared (included as Attachment 2). The recommended EPG specifica- tions, test protocols, and changes to the current test method will be particularly useful to highway agencies as they will help identify emulsions that will provide the desired properties and performance of the specific PST type and thus accrue the anticipated benefits. Five appendices contained in the research agency’s final report provide detailed informa- tion on the different aspects of the research. These appendices can be accessed on the TRB website (www.trb.org) by searching on NCHRP Research Report 837.

1 Summary 3 Chapter 1 Research Approach 5 Chapter 2 Results, Interpretation, and Applications 5 2.1 Critical Distresses and Characterization of Material Properties Related to PST Performance 5 2.1.1 Typical Materials Used for Surface Treatments 6 2.1.2 Distress Types in Asphalt Surface Treatments That Are Affected by Binder Properties 8 2.1.3 Review of Existing Specifications for Surface Treatments 8 2.1.4 Material Properties Related to Performance and Test Methods Used in Proposed EPG Specifications 13 2.2 Test Materials for the Development of the Performance-Graded Specifications 14 2.2.1 Selection of Emulsion Materials 15 2.2.2 Emulsion Acquisition 16 2.3 Performance-Graded Specifications Framework 16 2.3.1 Intended Use of the EPG Specifications 17 2.3.2 EPG Specification Design Temperature Grade Concepts 20 2.3.3 Traffic Designations for the EPG Specifications 20 2.3.4 Binder Grade Naming Designations for EPG Specifications 21 2.3.5 Underlying Concept and Outline for the Development of the EPG Specifications 23 2.4. Performance-Graded Specification Limits 23 2.4.1 Fresh Asphalt Emulsion EPG Specification Limits 25 2.4.2 Residual Binder Test Limits 50 2.5 Performance-Graded Specifications in Practice 50 2.5.1 Estimated EPG Specification Testing Time 50 2.5.2 Equipment Required for Test Methods Used in EPG Specifications 50 2.5.3 Implications of Three Levels of Traffic in the EPG Specifications 51 2.5.4 Emulsion Grading Example for EPG Specifications 51 2.6 Short-Term Validation of Performance-Graded Specifications 51 2.6.1 Chip Seal Short-Term Validation 54 2.6.2 Microsurfacing Short-Term Validation 57 Chapter 3 Summary and Recommendations for Research 57 3.1 Summary of EPG Specification Features 57 3.2 Recommendations for Future Research C O N T E N T S

59 References 61 Attachment 1 Proposed Specifications 84 Attachment 2 Proposed Test Methods