National Academies Press: OpenBook
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures. Washington, DC: The National Academies Press. doi: 10.17226/25432.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures. Washington, DC: The National Academies Press. doi: 10.17226/25432.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures. Washington, DC: The National Academies Press. doi: 10.17226/25432.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures. Washington, DC: The National Academies Press. doi: 10.17226/25432.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures. Washington, DC: The National Academies Press. doi: 10.17226/25432.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures. Washington, DC: The National Academies Press. doi: 10.17226/25432.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures. Washington, DC: The National Academies Press. doi: 10.17226/25432.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures. Washington, DC: The National Academies Press. doi: 10.17226/25432.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

2019 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 912 Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures Elzly TEchnology corporaTion Vineland, NJ Subscriber Categories Construction • Maintenance and Preservation • Materials 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, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transporta- tion results in increasingly complex problems of wide interest to high- way 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 techniques—the 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 TRB’s 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; TRB’s 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&I’s 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 912 Project 10-97 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-48043-7 Library of Congress Control Number 2019942233 © 2019 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 manufacturers’ 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 Board’s 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 CRP STAFF FOR NCHRP RESEARCH REPORT 912 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Edward T. Harrigan, Senior Program Officer Anthony P. Avery, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications Scott E. Hitchcock, Senior Editor NCHRP PROJECT 10-97 PANEL Area of Materials and Construction—Field of Specifications, Procedures, and Practices John C. Rogers, Elk Grove, CA (Chair) Scott B. Stotlemeyer, Missouri DOT, Jefferson City, MO William E. Ahearn, Barre, VT Justin Cook, Madison, AL Joshua F. Johnson, Bentley Systems, Ft. Collins, CO David Kuniega, Pennsylvania DOT, Harrisburg, PA Mohamed Mahgoub, New Jersey Institute of Technology, Mount Laurel, NJ Kelly L. Morse, Illinois DOT, Springfield, IL Marta Vasquez, Baton Rouge, LA Justin M. Ocel, FHWA Liaison

F O R E W O R D By Edward T. Harrigan Staff Officer Transportation Research Board NCHRP Research Report 912 presents practical means and methods for the effective detection and remediation of soluble salt contamination on highway steel structures. The guide will be of immediate interest to engineers in state highway agencies and industry with responsibility for the construction, maintenance, and rehabilitation of these structures. Effective detection and remediation of soluble salt contamination are essential to maxi- mizing the life of structural steel protective coatings. When present on a prepared surface, these salts are known to impact coating performance. Soluble salts may cause osmotic blistering or increase steel corrosion at defects in the coating. Current test methods may not be entirely successful in either evaluating problematic soluble salt levels prior to coating when the salts are concentrated randomly in “hot spots” (i.e., in pits in the steel) or confirm- ing that a remediated surface has a soluble salt level below an acceptance limit designated by a coating specifier. Surface preparation methods used during coating of steel structures remediate (i.e., remove) soluble salts with varying degrees of effectiveness. Past research has shown that pressure washing, abrasive blasting, or a combination of the two are not always successful in removing hot spots. The objectives of this research were to (1) evaluate the effectiveness of existing and new methods for detecting the location, distribution, and concentration of soluble salts on steel highway structures; (2) evaluate the effectiveness of existing and new remediation methods for soluble salts; (3) propose effective practices, specifications, or methods for detection and remediation of soluble salts; and (4) develop training materials for the design, specification, and field application of the detection and remediation methods by steel structure owners. The research was performed by Elzly Technology Corporation, Vineland, New Jersey. The research encompassed nearly 2,500 soluble salt measurements recorded in field and laboratory evaluations with eight commercial detection methods. The results indi- cated that each detection method has strengths and weaknesses, and that, overall, there is considerable variability in the soluble salt levels detected on representative bridge surfaces. Over 20 combinations of commercially used soluble salt remediation techniques were then evaluated in a laboratory setting. In addition, over 250 rusted-then-remediated test panels were coated and exposed in natural and accelerated tests. The results showed that a combination of mechanical and water methods is the most effective way to reduce salts to the maximum levels commonly used in highway bridge coating specifications. Panel testing further confirmed that industry standard levels for soluble salt contamination provide enough margin of error to account for the measurement and sampling variability observed in this project.

The key products of the project are a comprehensive, practical guide (this report) of means and methods for effective detection and remediation of soluble salt contamination on highway steel structures and supporting training materials. The research is fully documented in two volumes. This report, NCHRP Research Report 912, is the first volume; it contains the guide and the following four appendices: Appendix A: The Society for Protective Coatings (SSPC) Technology Guide 15, Field Methods for Extraction and Analysis of Soluble Salts on Steel and Other Nonporous Substrates, Appendix B: Training: Introduction to Soluble Salts, Appendix C: Training: Detection of Soluble Salt Contamination, and Appendix D: Training: Remediation of Soluble Salt Contamination. The second volume, titled Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures is a technical report presenting the results of the laboratory and field testing and their analyses that support the guidance contained in NCHRP Research Report 912. This technical report can be downloaded from the NCHRP Project 10-97 summary website at https://apps.trb.org/cmsfeed/TRBNetProjectDisplay. asp?ProjectID=3863. The NCHRP Research Report 912 Appendices B, C, and D PowerPoint presentations can be found on the TRB website (www.trb.org) by searching for “NCHRP Research Report 912.”

C O N T E N T S 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. 1 Chapter 1 Introduction 1 Scope 1 Technical Background 3 Chapter 2 Key Issues for Salt Detection and Remediation 3 When Is There a Significant Corrosion Risk Associated with Soluble Salt Contamination? 4 What Indicator of Soluble Surface Salts Should Be Measured? 6 How Much Salt Should Be Allowed on Surfaces Prior to Painting? 6 How Should Soluble Salts Be Detected? 8 Where and How Often Should an Inspector Measure Soluble Salt Concentrations? 9 What Are the Best Practices to Remediate Soluble Salts? 11 How Much Effort (Cost) Is Required to Remediate Soluble Salt Contamination? 11 What Are Some Examples of Specification Language for Allowable Soluble Salt Concentration? 12 What Industry Standards Exist Relating to Soluble Salt Detection and Remediation? 14 Endnotes A-1 Appendix A The Society for Protective Coatings (SSPC) Technology Guide 15, Field Methods for Extraction and Analysis of Soluble Salts on Steel and Other Nonporous Substrates B-1 Appendix B Training: Introduction to Soluble Salts C-1 Appendix C Training: Detection of Soluble Salt Contamination D-1 Appendix D Training: Remediation of Soluble Salt Contamination

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Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures Get This Book
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TRB’s National Cooperative Highway Research Program (NCHRP) Research Report 912: Guidelines for Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures consolidates practical guidance on the detection and remediation of soluble salt contamination prior to coating steel highway structures.

Soluble salts are those that dissociate in solution into anionic and cationic components. The soluble salts referenced in this guideline are soluble in water at nominal room temperatures. Soluble salts may be transferred to a steel bridge structure as an airborne aerosol (generally from marine or industrial sources), wind-blown debris, and debris transferred from vehicles or rainwater. In many cold climates, the most common source of soluble salts on bridges is deicing materials.

The report presents a brief background on soluble salts as well as information in the form of responses to a series of practical questions that an inspector, contractor, or designer may pose. Appendices B through D of the report are also available in PowerPoint format.

Appendix B – Training: Introduction to Soluble Salts

Appendix C – Training: Detection of Soluble Salt Contamination

Appendix D – Training: Remediation of Soluble Salt Contamination

The contractor’s final report, titled Detection and Remediation of Soluble Salt Contamination Prior to Coating Steel Highway Structures, is a technical report presenting the results of the laboratory and field testing and their analyses that support the guidance contained in NCHRP Research Report 912. This contractor’s final report and associated appendices can be found on the NCHRP Project 10-97 web page.

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