Corrosion Prevention for Extending the Service Life of Steel Bridges (2018)

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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 • Design • 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 © 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. 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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. O’Donnell, 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 Officials—through the mechanism of the National Cooperative Highway Research Program—authorized the Transportation Research Board to undertake a continuing study. This study, NCHRP Project 20-05, “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 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 corrosion—an important issue, not only by itself, but as part of the ever-increasing concern over the nation’s 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 “coated steels” and “uncoated steels.” 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 use—although somewhat limited currently—of 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 study’s 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 “NCHRP Synthesis 517.”

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