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2018 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 878 Validation of the Louisiana Interlayer Shear Strength Test for Tack Coat Louay N. Mohammad Mostafa A. Elseifi Ramendra Das Wei Cao Louisiana TransporTaTion research cenTer Louisiana sTaTe universiTy Baton Rouge, LA Subscriber Categories Constructionâ â¢â Materialsâ â¢â Pavements 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 techniquesâthe 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 TRBâs 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; TRBâs relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway 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 transportation departments, by committees of AASHTO, and by the Federal Highway Administration. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&Iâs recommendations are proposed to the AASHTO Board of Direc- tors and the National 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 National Academies 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 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 878 Project 09-40A ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-44686-0 Library of Congress Control Number 2018937214 Â© 2018 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. 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 manufacturersâ 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. 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 National 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 Boardâs 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 AUTHOR ACKNOWLEDGMENTS The research reported here was performed under NCHRP Project 09-40A. The Louisiana Transporta- tion Research Center was the contractor for this study. The research team gratefully acknowledges the participation and cooperation of the state departments of transportation, industry associations, material suppliers, and contractors in providing the test sections, tack coat products, application equipment, and other associated supports throughout the course of the project. The authors also acknowledge the assis- tance of the Technical Review Panel for NCHRP Project 09-40A. DISCLAIMER The opinions and conclusions expressed or implied are those of the research agency that performed the research and are not necessarily those of the Transportation Research Board or its sponsors. This report has not been reviewed or accepted by the Transportation Research Boardâs Executive Committee or the Governing Board of the National Research Council. CRP STAFF FOR NCHRP RESEARCH REPORT 878 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Edward Harrigan, Senior Program Officer Anthony P. Avery, Senior Program Associate Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications Ann E. Petty, Senior Editor NCHRP PROJECT 09-40A PANEL Field of Materials and ConstructionâArea of Bituminous Materials Gloria Burke, Hagerstown, MD (Chair) Jack E. Cowsert, ECS Carolinas, LLP, Raleigh, NC Dale S. Decker, Dale S. Decker, LLC, Eagle, CO Roger C. Olson, Bloomington, MN Murari M. Pradhan, Arizona Department of Transportation, Phoenix, AZ Gregory A. Sholar, Florida Department of Transportation, Gainesville, FL Matthew Corrigan, FHWA Liaison
F O R E W O R D This report presents the results of a comprehensive field validation of AASHTO TP 114: âStandard Method of Test for Determining the Interlayer Shear Strength (ISS) of Asphalt Pavement Layers.â The report will be of immediate interest to the staffs of state highway agencies, materials suppliers, and paving contractors with the responsibility for the selection, evaluation, and application of tack coat materials. NCHRP Project 09-40, âOptimization of Tack Coat for HMA Placement,â which was completed in 2011, developed, among other things, AASHTO TP 114: âStandard Method of Test for Determining the Interlayer Shear Strength (ISS) of Asphalt Pavement Layers.â The objective of NCHRP Project 09-40A was to evaluate and to validate test method AASHTO TP 114 by correlating measured tack coat parameters with asphalt pavement performance at field projects constructed across the United States to support its imple- mentation. The research was conducted by the Louisiana Transportation Research Center, Louisiana State University, Baton Rouge. In the research, test method AASHTO TP 114 was used to measure the tack coat ISS on 10 field projects constructed in six states. The 10 projects included 33 in-service test sections for the evaluation of the effects of tack coat material type, pavement surface type, residual application rate, and time in service on the ISS. Further, an interface shear strength predictive model was developed for use by practitioners during the planning of overlay construction activities, selection of tack coat material type, and calculation of application rate, given the project conditions. The research demonstrated that the ISS values measured with test method AASHTO TP 114 correlated well with short-term cracking performance of the field pavements and verified that a minimum ISS of 40 psi was required for satisfactory tack coat performance. The research also established the effects of tack coat material type, pavement surface type, residual application rate, and time in service on ISS development. The practical outcome of the project is the validation of the utility of test method AASHTO TP 114 along with its threshold value of 40 psi to assess the effectiveness of tack coats to bond asphalt pavement layers to underlying asphalt or portland cement concrete surfaces. This report fully documents the research and includes three appendices presenting (1) the field project checklist, (2) photos of existing pavement distress at the Oklahoma and Louisiana field projects, and (3) a summary of test data from the field projects. ByâEdwardâHarrigan StaffâOfficer TransportationâResearchâBoard
C O N T E N T S 1â Summary 3 Chapter 1â IntroductionâandâResearchâApproach 3 1.1 Problem Statement 3 1.2 Research Objective 3 1.3 Research Scope 4 1.4 Research Approach 5 Chapter 2â StateâofâPractice 5 2.1 Tack Coat Materials 6 2.2 Characterization of Interface Bond Strength 11 Chapter 3â ExperimentalâProgram 11 3.1 Introduction 11 3.2 Project Identification 11 3.3 Project Description 14 3.4 Tack Coat Application and Overlay Construction 20 3.5 Laboratory Characterization 22 Chapter 4â ResultsâandâAnalysis 22 4.1 Rheological Properties of Tack Coat Materials 22 4.2 Pavement Surface Texture Depths 24 4.3 ISS Test Results 26 4.4 Effect of Tack Coat Material Type on ISS 29 4.5 Effect of Pavement Surface Type on ISS 30 4.6 Effect of Residual Application Rate on ISS 32 4.7 Effect of Service Time on ISS 36 4.8 Analysis of FWD Test Results 39 4.9 Relationship Between ISS and FWD Center Deflection 40 4.10 Short-Term Performance of Test Sections 41 4.11 ISS Predictive Model Development 41 4.12 Data Description for Model Development 42 4.13 Model Development Methodology 43 4.14 Multiple Linear Regression Analysis 47 4.15 Nonlinear Regression Analysis 48 4.16 Illustrative Applications of the ISS Predictive Model 50 Chapter 5â SummaryâandâConclusions 50 5.1 Conclusions 51 5.2 Implementation of Research Products
52â References 55 Appendix A 57 Appendix B 59 Appendix C Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.trb.org) retains the color versions.