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Publication Number: FHWA-HRT-11-046
Date: June 2011

Performance Evaluation of One-Coat Systems for New Steel Bridges

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The current state of art for corrosion protection of steel bridges involves a three-coat system typically consisting of a zinc-rich primer, an intermediate coat, and a top coat. Replacing a three-coat system with fewer coats without sacrificing corrosion resistance can lead to savings in production cost and improved productivity in the steel shops. Two-coat systems evaluated in a previous Federal Highway Administration study performed on par with the widely established well-performing zinc-rich three-coat systems. In this in-house one-coat study, commercially available coating materials that can be applied as one-coat systems to new steel bridges were evaluated. Eight one.coat systems and two controls, a three-coat and a two-coat system, were chosen, and their performance was evaluated using accelerated laboratory testing (ALT) and two outdoor exposure conditions, natural weathering (NW) and natural weathering with salt spray (NWS). ALT (6,840 h) and the two outdoor exposure conditions (NW and NWS), both 18 months, were performed at the Coatings and Corrosion Laboratory at the Turner-Fairbank Highway Research Center in McLean, VA, while another outdoor exposure was performed at a marine exposure site for 24 months in Sea Isle City, NJ. The purpose of this study was to evaluate the performance ranking of various one-coat test systems.

Jorge Pagán-Ortiz
Director, Office of Infrastructure
Research and Development


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Technical Report Documentation Page

1. Report No.


2. Government Accession No. 3. Recipient’s Catalog No.

4. Title and Subtitle

Performance Evaluation of One-Coat Systems for New Steel Bridges

5. Report Date

June 2011

6. Performing Organization Code

7. Author(s)

Yuan Yao, Pradeep Kodumuri, and Seung-Kyoung Lee

8. Performing Organization Report No.

9. Performing Organization Name and Address

SES Group and Associates
614 Biddle City
Chesapeake City, MD 21915

Center for Advanced Infrastructure & Transportation
Rutgers, the State University of New Jersey 100 Brett Road
Piscataway, NJ 0854

10. Work Unit No.
11. Contract or Grant No.

12. Sponsoring Agency Name and Address

Office of Infrastructure Research and Development

Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101-2296

13. Type of Report and Period Covered
Final Report

14. Sponsoring Agency Code

15. Supplementary Notes

The Federal Highway Administration Managers were Seung-Kyoung Lee (now at Rutgers) and Y.P.Virmani, HRDI-60.

16. Abstract

In an effort to address cost issues associated with shop application of conventional three-coat systems, the Federal Highway Administration completed a study to investigate the performance of eight one-coat systems and two control coatings for corrosion protection of highway bridges. Based on prior performance, a three-coat system and a two-coat system were selected as the control coating systems. The performance of all coating systems was evaluated under accelerated laboratory and outdoor exposure conditions. Accelerated testing was performed in the laboratory for 6,840 h. Natural weathering exposure was performed in the outdoor environment for 18 months and at a marine exposure site for 24 months. A calcium sulfonate alkyd coating system was found to perform equally in comparison with the three-coat system; however, curing was a major concern. Regression analysis was used to identify correlations between color, gloss, adhesion strength, and coating defects for one-coat systems.

17. Key Words

One-coat, Two-coat, Three-coat, Steel bridge coatings, Corrosion protection, Accelerated testing, Outdoor exposure, Coating performance evaluation

18. Distribution Statement

No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161

19. Security Classif. (of this report)


20. Security Classif. (of this page)


21. No. of Pages


22. Price

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

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