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REPORT
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Publication Number:  FHWA-HRT-20-065    Date:  September 2020
Publication Number: FHWA-HRT-20-065
Date: September 2020

 

Coating Performance on Existing Steel Bridge Superstructures

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FOREWORD

This report documents a study that evaluated the corrosion protection performance of four coating systems applied to steel substrates with various chloride contamination levels. The purpose of the study was to identify coating systems that can provide extended service life for steel bridges with minimal surface preparation. This study helps estimate the amount of chloride contamination that coating systems can tolerate without premature failure. Owners, consultants, contractors, and technical experts interested in the durability of coatings applied to contaminated steel substrates may benefit from the information contained herein.

Cheryl Allen Richter, P.E., Ph.D.
Director, Office of Infrastructure
Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation (USDOT) in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

 

Technical Report Documentation Page

1. Report No.

FHWA-HRT-20-065

2. Government Accession No. 3. Recipient's Catalog No.
4. Title and Subtitle

Coating Performance on Existing Steel Bridge Superstructures

5. Report Date

September 2020

6. Performing Organization Code
7. Author(s)

R. Liu and A. Runion

8. Performing Organization Report No.
9. Performing Organization Name and Address

SES Group & Associates, LLC
614 Biddle Street
Chesapeake City, MD 21915

10. Work Unit No. (TRAIS)
11. Contract or Grant No.

DTFH61-17-D-00017

12. Sponsoring Agency Name and Address

Office of Infrastructure Research and Development
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101

13. Type of Report and Period Covered

Final Report; June 2014–December 2019

14. Sponsoring Agency Code

HRDI-10

15. Supplementary Notes

For this research, the Contracting Officer's Representatives were Chip Becker (HRDI-10) and later Frank Jalinoos (HRDI-30), Corrosion and Coatings Program Managers.

16. Abstract

This study evaluated the performance of four coating systems applied on chloride-contaminated steel substrates. The purpose of the study was to identify coating systems that can provide extended service life for steel bridges with minimal surface preparation at a much reduced cost. The study helps estimate the amount of chloride contamination coating systems can tolerate without significant premature failure. The chloride contamination levels tested in this study were 0, 20, and 60 μg/cm2. The coating systems tested were two 3-coat systems (one with inorganic zinc-rich primer and the other with organic zinc-rich primer), a 2-coat system with carbon nanotubes in its zinc-rich primer, and a 1-coat system of high-ratio calcium sulfonate alkyd. Coated panels were exposed to two conditions: accelerated laboratory testing and outdoor natural weathering. The 3-coat systems had the best corrosion protection performance among the tested specimens. The inorganic zinc primer performed slightly better than the organic zinc primer. The 2-coat system demonstrated the highest adhesion strength over all levels of chloride contamination.

17. Key Words

Coating, chloride, corrosion

18. Distribution Statement

No restrictions. This document is available through the National Technical Information Service, Springfield, VA 22161.
http://www.ntis.gov

19. Security Classification
(of this report)

Unclassified

20. Security Classification
(of this page)

Unclassified

21. No. of Pages

47

22. Price

N/A

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
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