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NAT IONAL COOPERAT IVE H IGHWAY RESEARCH PROGRAM NCHRP SYNTHESIS 500 Research Sponsored by the American Association of State Highway and Transportation Officials in Cooperation with the Federal Highway Administration SubScriber categorieS Bridges and Other Structures â¢ Construction â¢ Highways â¢ Materials Control of Concrete Cracking in Bridges A Synthesis of Highway Practice conSultant Henry G. Russell Henry G. Russell, Inc. Glenview, Illinois 2017
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 stud- ied 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 interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Associa- tion of State Highway and Transportation Officials (AASHTO) in 1962 initiated 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 Acad- emies 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 rea- sons: TRB maintains an extensive committee 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, universities, and industry; TRBâs relationship to the Academies is an insurance of objectivity; and TRB maintains a full-time staff of specialists 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 identi- fied by chief administrators and other staff of the highway and trans- portation departments and by committees of AASHTO. Topics of the highest merit are selected by the AASHTO Standing Committee on Research (SCOR), and each year SCORâs 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 propos- als. Administration and surveillance of research contracts are the responsibilities of the Academies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving highway transportation prob- lems 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 SYNTHESIS 500 Project 20-05, Topic 47-01 ISSN 0547-5570 ISBN 978-0-309-38981-5 Library of Congress Control No. 2016957897 Â© 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 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 necessari- ly 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 con- sidered 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 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.
TOPIC PANEL 47-01 JOHN BELCHER, Michigan Department of Transportation, Lansing BIJAN KHALEGHI. Washington State Department of Transportation, Tumwater WILL LINDQUIST, Kansas Department of Transportation, Topeka WILLIAM POTTER, Florida Department of Transportation, Tallahassee CARIN L. ROBERTS-WOLLMANN, Virginia Polytechnic Institute and State University, Blacksburg AMY E. SMITH, HDR, Austin, TX BENJAMIN A. GREYBEAL, Federal Highway Administration (Liaison) REGGIE H. HOLT, 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 MARIELA GARCIA-COLBERG, Senior Program Officer JO ALLEN GAUSE, Senior Program Officer GAIL R. STABA, 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 J. HEDGES, Interim Director, Cooperative Research Programs 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 âCOCOâ BRISENO, California Department of Transportation DAVID M. JARED, Georgia Department of Transportation CYNTHIA L. JONES, Ohio Department of Transportation MALCOLM T. KERLEY, NXL, Richmond, Virginia JOHN M. MASON, JR., Auburn University CATHERINE NELSON, Salem, Oregon ROGER C. OLSON, Minnesota Department of Transportation (Ret.) BENJAMIN ORSBON, South Dakota Department of Transportation RANDY PARK, Utah Department of Transportation ROBERT L. SACK, New York State Department of Transportation FRANCINE SHAW WHITSON, Federal Highway Administration JOYCE N. TAYLOR, Maine Department of Transportation FHWA LIAISON JACK JERNIGAN TRB LIAISON STEPHEN F. MAHER Cover figure: End zone cracks in a prestressed concrete beam (Courtesy: University of Wisconsin and Concrete Bridge Views published jointly by FHWA and the National Concrete Bridge Council).
FOREWORd Highway administrators, engineers, and researchers often face problems for which infor- mation already exists, either in documented form or as undocumented experience and prac- tice. 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 alleviat- ing 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 Officialsâthrough the mechanism of the National Cooperative Highway Research Programâauthorized the Transportation Research Board to undertake a continuing study. This study, NCHRP Proj- ect 20-5, âSynthesis of Information Related to Highway Problems,â searches out and syn- thesizes 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. Cracking of concrete in bridges continues to be a concern for bridge owners, particularly with bridge decks exposed to severe environments. The control of cracking for aesthetic, durability, and structural reasons becomes increasingly important as service-life goals are extended and higher-strength concrete, higher-strength reinforcement, and different types of reinforcement are used in bridge construction. This study provides information on methods used to control concrete cracking in bridge superstructures and substructures, and on the influence of cracking on long-term durability. The study found that no single best practice can be used to enhance concrete bridge deck performance. Useful practices include reducing drying shrinkage of the concrete mix; reducing temperature differences; nighttime concrete placements; and the use of supple- mentary cementitious materials, internal curing, shrinkage-reducing admixtures, or shrinkage- compensating concrete. Wet curing of concrete decks beginning immediately after concrete finishing and continuing for at least 7 days, followed by the application of a curing com- pound, was identified as an appropriate construction practice for concrete bridge decks. For prestressed concrete beams, end zone cracking can often be prevented by revising the detensioning sequence. Cracking in concrete substructures was of less concern than in super- structure components. Henry G. Russell, Henry G. Russell, Inc., Glenview, Illinois, 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. PREFACE By Jon M. Williams Program Director Transportation Research Board
INTROduCTION In 1969, the U.S.DOT was two years old, the Boeing 747 made its first flight, and Apollo 11 landed on the moon. The Woodstock music festival was held in upstate New York, Wal-Mart was founded, and the âMiracle Metsâ won the World Series. At the Highway Research Board (now TRB), the NCHRP had been in existence for just seven years. In the late â60s, something had become clear to the staff and sponsors: not every problem faced by transportation practitioners required new research. Many state and local agencies developed their own solutions to day-to-day problems and issues, but had no idea what practices were being employed by their colleagues across the country, or how effective they were. As it was phrased at the time, âThere exists a vast storehouse of information relating to nearly every subject of concern to highway administrations and engineers. Much of it results from research and much from successful application of the engineering ideas of men faced with problems in their day to day work.â Setting aside the quaint notion that in 1969 apparently only men had engineering ideas, the idea was born for a new program to seek out, compile, and synthesize the most useful knowledge and current practices for the benefit of transportation practitioners. NCHRP Synthesis No. 1 dealt with a topic that is still of vital importance today: the safety of road maintenance workers. The report Traffic Control for Freeway Maintenance documented how agencies supplemented the Manual on Uniform Traffic Control Devices with standard worksite layouts and detailed instructions on their placement and removal. The Synthesis outlined how some agencies provided additional signing and lighting to accommodate night work, including âelectric lights placed under translucent plastic traffic cones.â Four hundred and ninety-nine (499) studies later, the Synthesis of Practice is consistently the highest rated annual project by NCHRPâs governing board, the AASHTO Standing Committee on Research and its Research Advisory Committee. The time and money saved by identifying and employing practices documented in the Synthesis series have saved countless dollars, time, and lives. Incidentally, the first syntheses included a postage-paid postcard that could be filled out and returned with responses to two questions: how did readers apply the information in the synthesis, and how could the synthesis be improved to be more effective? As TRB continues to seek ways to understand and maximize the impacts of its work, these two questions are as relevant today as they were in 1969. Donât expect to see postcards that require a hand-written response, but donât be sur- prised to see us asking these two simple questions more often in the future. Neil Pedersen, Executive Director Transportation Research Board
CONTENTS 1 SUMMARY 3 CHAPTER ONE INTRODUCTION Background, 3 Objectives and Scope, 3 Study Approach, 4 Report Organization, 4 5 CHAPTER TWO TYPES AND CAUSES OF CONCRETE CRACKING IN BRIDGES Plastic Shrinkage Cracks, 5 Plastic Settlement Cracks, 5 Autogenous Shrinkage, 6 Drying Shrinkage Cracks, 6 Thermal Cracks, 6 Cracking in Bridge Decks, 6 Cracking in Adjacent Box Beam Bridges and Slab Beam Bridges, 19 Cracking in Pretensioned Concrete Beams, 21 Cracking in Nonprestressed Concrete Beams, 25 Cracking in Substructures, 26 Effective Practices for Control of Concrete Cracking, 28 31 CHAPTER THREE EFFECTS OF CONCRETE CONSTITUENT MATERIALS ON CRACKING Concrete Constituent Materials for Bridge Decks, 31 Concrete Constituent Materials for Other Components, 36 Internal Curing, 37 Self-Consolidating Concrete, 39 Summary of the Effects of Concrete Constituent Materials, 39 40 CHAPTER FOUR EFFECTS OF CONSTRUCTION PRACTICES ON CRACKING Curing Practices, 40 Weather Conditions, 42 Placement Length and Construction Sequence, 42 Other Practices, 43 Summary of Construction Practices, 43 44 CHAPTER FIVE EFFECTS OF REINFORCEMENT TYPE ON CRACK CONTROL Yield Strength of Reinforcement, 44 Corrosion-Resistant Steel Reinforcement, 44 Fiber-Reinforced Polymer Reinforcement, 45 Specifications for Crack Control, 47 Conclusions About the Effects of Reinforcement Type on Crack Control, 53
54 CHAPTER SIX INFLUENCE OF CRACKING ON LONG-TERM BRIDGE PERFORMANCE AASHTO LRFD Specifications for Durability, 56 Permissible Crack Widths, 56 Determination of Bar Spacing to Control Crack Widths, 57 Service Life, 59 Conclusions About the Influence of Cracking on Long-Term Bridge Performance, 60 61 CHAPTER SEVEN CASE EXAMPLES California Department of Transportation, 61 Kansas Department of Transportation, 62 Pennsylvania Department of Transportation, 64 Washington State Department of Transportation, 65 68 CHAPTER EIGHT CONCLUSIONS AND SUGGESTIONS FOR FUTURE RESEARCH Conclusions, 68 Suggestions for Future Research, 70 72 ABBREVIATIONS 73 REFERENCES 83 APPENDIX A SURVEY QUESTIONNAIRE 88 APPENDIX B SUMMARY OF RESPONSES TO SURVEY QUESTIONNAIRE 101 APPENDIX C CROSS REFERENCE TABLE FOR AASHTO LRFD BRIDGE DESIGN SPECIFICATIONS 102 APPENDIX D RESEARCH PROBLEM STATEMENT 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.