Methods and Practices on Reduction and Elimination of Asphalt Mix Segregation (2015)

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NAT IONAL COOPERAT IVE H IGHWAY RESEARCH PROGRAM NCHRP SYNTHESIS 477 TRANSPORTATION 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 SubScriber categorieS Highways  •  Materials Methods and Practices on Reduction and Elimination of Asphalt Mix Segregation A Synthesis of Highway Practice conSultant Mary Stroup-Gardiner Gardiner Technical Service Monterey, California

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. 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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 SYNTHESIS 477 Project 20-05, Topic 45-12 ISSN 0547-5570 ISBN 978-0-309-27182-0 Library of Congress Control No. 2015933592 © 2015 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their manuscripts 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 non of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMSCA, 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 development 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 Co- operative 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 of the 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. NOTE: 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.

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TOPIC PANEL 45-12 CATHRINA BARROS, California Department of Transportation, Sacramento FREDERICK HEJL, Transportation Research Board RICHARD M. HEWITT, Florida Department of Transportation, Deland BAOSHAN HUANG, University of Tennessee, Knoxville GERALD A. HUBER, Heritage Research Group, Indianapolis, IN GREGORY D. JOHNSON, Minnesota Department of Transportation, Maplewood JEFFREY MANN, New Mexico Department Transportation, Santa Fe JEFFREY S. UHLMEYER, Washington State Department of Transportation, Tumwater BRAD NEITZKE, Federal Highway Administration (Liaison) JOHN S. YOUTCHEFF, Federal Highway Administration (Liaison) SYNTHESIS STUDIES STAFF STEPHEN R. GODWIN, Director for Studies and Special Programs JON M. WILLIAMS, Program Director, IDEA and Synthesis Studies JO ALLEN GAUSE, Senior Program Officer GAIL R. STABA, Senior Program Officer DONNA L. VLASAK, Senior Program Officer TANYA M. ZWAHLEN, Consultant DON TIPPMAN, Senior Editor CHERYL KEITH, Senior Program Assistant DEMISHA WILLIAMS, Senior Program Assistant DEBBIE IRVIN, Program Associate COOPERATIVE RESEARCH PROGRAMS STAFF CHRISTOPHER W. JENKS, Director, Cooperative Research Programs CHRISTOPHER HEDGES, Manager, National Cooperative Highway Research Program EILEEN P. DELANEY, Director of Publications NCHRP COMMITTEE FOR PROJECT 20-05 CHAIR BRIAN A. BLANCHARD, Florida Department of Transportation MEMBERS STUART D. ANDERSON, Texas A&M University SOCORRO “COCO” BRISENO, California Department of Transportation CYNTHIA J. BURBANK, FHWA (retired) CYNTHIA L. GERST, Ohio Department of Transportation MALCOLM T. KERLEY, Virginia Department of Transportation (retired) JOHN M. MASON, JR., Auburn University CATHERINE NELSON, Salem, Oregon RANDALL R. “RANDY” PARK, Utah Department of Transportation ROGER C. OLSON, Minnesota Department of Transportation BENJAMIN I. ORSBON, South Dakota Department of Transportation ROBERT L. SACK, New York State Department of Transportation JOYCE N. TAYLOR, Maine Department of Transportation FRANCINE SHAW WHITSON, Federal Highway Administration FHWA LIAISONS JACK JERNIGAN MARY LYNN TISCHER TRB LIAISON STEPHEN F. MAHER Cover figure: Credit: Mary Stroup-Gardiner.

FOREWORD The report documents methods and practices on reduction and elimination of asphalt mix segregation. This synthesis provides guidance on how to reduce or eliminate segrega- tion during aggregate production, mix design, asphalt mix production, mix transport and transfer, and placement. Successful options for reducing or eliminating segregate, as well as caveats for what not to do, are included for the following topics: segregation descriptions and segregation specifications (standard sections, advantages, disadvantages, incentives/ disincentives, and desired changes). A survey was sent to members of the American Association of State Highway and Trans- portation Officials (AASHTO) Committee on Construction (with a 96% state response rate). The same on-line survey was submitted to state Asphalt Pavement Association (APA) representatives to collect information from the paving industry’s perspective on successful construction equipment and practices for minimizing or eliminating segregation, as well. Mary Stroup-Gardiner, Gardiner Technical Service, Monterey, California, collected and synthesized the information and wrote the report. The members of the topic panel are acknowledged on the preceding page. This synthesis is an immediately useful document that records the practices that were acceptable within the limitations of the knowledge available at the time of its preparation. As progress in research and practice continues, new knowledge will be added to that now at hand. Highway administrators, engineers, and researchers often face problems for which infor- mation already exists, either in documented form or as undocumented experience and practice. This information may be fragmented, scattered, and unevaluated. As a consequence, full knowledge of what has been learned about a problem may not be brought to bear on its solution. Costly research findings may go unused, valuable experience may be overlooked, and due consideration may not be given to recommended practices for solving or alleviating the problem. There is information on nearly every subject of concern to highway administrators and engineers. Much of it derives from research or from the work of practitioners faced with problems in their day-to-day work. To provide a systematic means for assembling and evaluating such useful information and to make it available to the entire highway commu- nity, the American Association of State Highway and Transportation Officials—through the mechanism of the National Cooperative Highway Research Program—authorized the Trans- portation Research Board to undertake a continuing study. This study, NCHRP Project 20-5, “Synthesis of Information Related to Highway Problems,” searches out and synthesizes useful knowledge from all available sources and prepares concise, documented reports on specific topics. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice. This synthesis series reports on current knowledge and practice, in a compact format, without the detailed directions usually found in handbooks or design manuals. Each report in the series provides a compendium of the best knowledge available on those measures found to be the most successful in resolving specific problems. PREFACE By Donna L. Vlasak Senior Program Officer Transportation Research Board

CONTENTS 1 SUMMARY 5 CHAPTER ONE INTRODUCTION Project Background, 5 Synthesis Objectives, 5 Synthesis Scope, 5 Report Organization, 5 7 CHAPTER TWO LITERATURE REVIEW Descriptions of Segregation, 7 End-of-Truck Segregation, 7 Random Segregation, 7 Longitudinal Segregation, 7 Temperature Segregation, 9 Detecting Segregation, 9 Visual Method, 9 Surface Texture, 10 Temperature Differences, 12 Ground Penetrating Radar, 14 Intelligent Compaction, 15 Summary of Methods for Detecting Segregation, 16 Testing, 16 Quality Control/Quality Assurance Testing, 18 Performance-Related Testing, 23 How and Where Mix Segregates, 24 Aggregate Production, 24 Mix Designs, 25 Asphalt Plants, 27 Mix Transfer from Haul Truck to Paver, 33 Paver, 38 Pavement Distresses and Pavement Condition in Segregated Areas, 41 Top-down Cracking, 42 Reflective Cracking, 42 Ride Quality, 43 Specifications, 44 Alberta, Canada, 44 Texas, 45 Research Development of Segregation Specifications, 46 47 CHAPTER THREE SURVEY RESULTS Descriptions, Detection, Responsibility, and Training, 47 Descriptions, 47 Detection, 47 Responsibility for Detecting Segregation, 47 Training and Certification Programs, 48 Testing, 50 Roadway Density Testing, 50 Laboratory Testing, 50

Specifications, 51 Incentives/Disincentives, 55 Advantages, 55 Disadvantages, 55 Dispute Resolution, 55 Desired Changes in Segregation Specification, 56 Summary of Segregation Specification Comments, 56 Pavement Distresses in Segregated Areas, 56 Reducing Segregation During Design, Production, and Placement, 57 Mix Designs, 57 Gradations and Mix Type, 58 Material and Mix Production, 60 Pavers, 63 66 CHAPTER FOUR CONCLUSIONS 74 ABBREVIATIONS AND ACRONYMS 75 REFERENCES 79 APPENDIX A ON-LINE SURVEY FORM 102 APPENDIX B RESPONDENTS 103 APPENDIX C CHECKLIST FOR REDUCING OR ELIMINATING SEGREGATION 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.