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Corrosion Prevention for Extending the Service Life of Steel Bridges A Synthesis of Highway Practice J. Peter Ault Elzly TEchnology corporaTion Vineland, NJ a n d Justin D. Dolph Elzly TEchnology corporaTion Reston, VA 2018 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¢ Design â¢ Maintenance and Preservation 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 SYNTHESIS 517
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 517 Project 20-05, Topic 48-03 ISSN 0547-5570 ISBN 978-0-309-39036-1 Library of Congress Control Number 2018945329 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 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. 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.
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.
CRP STAFF FOR NCHRP SYNTHESIS 517 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Crawford F. Jencks, Staff Officer Cheryl Keith, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications NCHRP PROJECT 20-05 PANEL Brian A. Blanchard, Florida DOT, Tallahassee, FL (Chair) Stuart D. Anderson, Texas A&M University, College Station, TX Socorro Briseno, California DOT, Sacramento, CA David M. Jared, Georgia DOT, Forest Park, GA Cynthia L. Jones, Ohio DOT, Columbus, OH Malcolm T. Kerley, NXL, Richmond, VA John M. Mason, Jr., Auburn University, Auburn, AL Roger C. Olson, Minnesota DOT, Bloomington, MN (retired) Benjamin T. Orsbon, South Dakota DOT, Pierre, SD Randall R. Park, Utah DOT, Salt Lake City, UT Robert L. Sack, New York State DOT, Albany, NY Francine Shaw Whitson, FHWA, Washington, DC Joyce N. Taylor, Maine DOT, Augusta, ME Jack Jernigan, FHWA Liaison Stephen F. Maher, TRB Liaison TOPIC 48-03 PANEL Caroline Rose Bennett, University of Kansas, Lawrence, KS Domenic A. Coletti, HDR, Raleigh, NC Steve C. Kahl, Michigan DOT, Lansing, MI Ivan R. Lasa, Florida DOT, Gainesville, FL Norman L. McDonald, Iowa DOT, Ames, IA (retired) John C. Rogers, Elk Grove, CA Hormoz Seradj, Oregon DOT, Salem, OR (retired) Donald R. Becker, FHWA Liaison Larry D. OâDonnell, FHWA Liaison James W. Bryant, Jr., TRB Liaison 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
FOREWORD Highway administrators, engineers, and researchers often face problems for which information already exists, either in documented form or as undocumented experience and practice. This infor- mation 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 evalu ating such useful information and to make it available to the entire highway community, the American Association of State High- way and Transportation Officialsâthrough the mechanism of the National Cooperative Highway Research Programâauthorized the Transportation Research Board to undertake a continuing study. This study, NCHRP Project 20-05, âSynthesis of Information Related to Highway Problems,â 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 Crawford F. Jencks Staff Officer Transportation Research Board One of the most often cited problems affecting not only the appearance, but more importantly, the structural integrity of steel bridges, is corrosionâan important issue, not only by itself, but as part of the ever-increasing concern over the nationâs aging and deteriorating infrastructure. A syn- thesis of current practices and existing knowledge on this particular problem seemed timely. Such a synthesis would provide a better understanding of how to help combat the problem and extend the service life of aging and newly designed steel bridges. The primary approaches for gathering information were through a literature review and a survey of transportation agencies. The technical literature reviewed included âcoated steelsâ and âuncoated steels.â Coated steel bridges were further divided by liquid coatings and metallic coatings (e.g., galvanizing and metallizing). Uncoated steels were predominately weathering-grade steels designed to form a protective rust layer (patina). The synthesis also reported on the useâalthough somewhat limited currentlyâof stainless steel for structural elements and various other components of bridge structures prone to corrosion. Forty-six state departments of transportation and three other bridge-owner agencies responded to the survey, which covered both maintenance and design. The survey addressed the challenges in making the optimal choices in design and maintenance, while recognizing that approaches will vary in different parts of the country. For example, techniques used in northern states, where deicing salts are a significant issue, may not offer much benefit in coastal states, where exposure to saltwater and sea air are of greater concern. J. Peter Ault, P.E., the studyâs principal investigator, assisted by Justin D. Dolph, collected and synthesized the information and wrote the report. The members of the topic panel are acknowl- edged on page iv. 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. Appendices A through E can be found at www.TRB.org by searching for âNCHRP Synthesis 517.â
1 Summary 3 Chapter 1 Introduction 3 Scope 4 Approaches to Corrosion Prevention of Steel Bridges 5 Study Approach and Report Organization 7 Chapter 2 Corrosion Prevention and Control for Steel Bridges 7 Corrosion-Prevention Options 7 Designing for Corrosion Prevention 9 Service Life Implications of Corrosion on Steel Bridges 10 Warranties for Corrosion Control 11 Corrosion-Control Maintenance 13 Maintaining Coated Steel Bridges 13 Maintaining Uncoated Steel Bridges 16 Relative Cost 19 Chapter 3 Corrosion Control of Uncoated Steel Bridges 19 Alternatives 19 History of Weathering Steel in Bridge Applications 20 Stainless Steels 20 History of ASTM A1010 Stainless Steel in Bridge Applications 21 Duplex Stainless Steels for Bridge Applications 22 Corrosion-Prevention Design Issues for Uncoated Steel Bridges 22 General Considerations 24 Design Detailing 29 Service Environment Considerations 32 Zone Painting 32 Corrosion Performance Specifications 33 Decision Process for Selecting Corrosion-Resistant Materials 36 Corrosion Maintenance of Uncoated Steel Bridges 37 Inspection 38 Cleaning/Washing 38 Zone Painting 41 Water Drainage 41 Full Painting of Aged, Uncoated, Corrosion-Resistant Steel Structures 42 Chapter 4 Corrosion Control of Coated Steel Bridges 43 Coating Material Alternatives 43 Liquid Coatings 46 Galvanizing 49 Metallizing 49 Duplex Coatings 50 Innovative Corrosion-Prevention Coatings for New Structures 51 Specifications C O N T E N T S
53 Corrosion-Prevention Design Issues for Coated Steel Bridges 53 Coating System Selection 56 Shop versus Field Application 57 Design Detailing 59 Service Environment Considerations 59 Zone Painting 59 Use of Warranties 60 Economics 60 Corrosion Maintenance Issues for Coated Steel Bridges 62 Do Nothing 62 Remove and Replace 62 Zone Painting 63 Spot Painting 63 Overcoating 63 Decision Process for Selecting Among Alternative Maintenance Practices 63 Integration of Painting and Structural Work 65 Chapter 5 Bridge Cleaning 65 Benefits of Bridge Cleaning 67 Bridge Cleaning with Additives 68 Chapter 6 Conclusions 68 Available Technologies 69 For the Bridge Designer 70 For the Bridge Maintainer 70 Steel Bridge Corrosion Research Needs 72 References 75 Appendices