The National Academies

NCHRP 10-37 [Completed]

Performance of Epoxy-Coated Reinforcing Steel in Highway Bridges

  Project Data
Funds: $350,000
Research Agency: Kenneth C. Clear, Inc./Florida Atlanta University
Principal Investigator: Mr. Kenneth C. Clear and Dr. William H. Hartt
Effective Date: 5/1/1991
Completion Date: 7/31/1994

The highway industry has made extensive use of epoxy-coated reinforcing steel bars in bridges during the last 15 years. Many states now specify epoxy-coated bars as the preferred protective system to reduce corrosion-induced deterioration in concrete bridge decks. As an extension of the concept, epoxy-coated reinforcing steel has also been used in concrete substructure elements although, there are differences in deck and substructure applications, especially, in respect to the size of the reinforcing steel and the amount of fabrication (i.e., the amount of bending of the steel bar after the epoxy coating has been applied).

This NCHRP research was prompted because of extensive premature corrosion of epoxy-coated reinforcing steel that had occurred in various substructure members of bridges built in the Florida Keys. Corrosion was initially observed in areas that contained bent reinforcing steel bars, but later it was also found on straight bars. These deteriorating members were in the "splash zone" and, thus, were subjected to salt spray and cycles of wetting and drying. High air and water temperatures also contributed to an adverse environment. In addition, other---albeit isolated and limited---instances of unsatisfactory performance of epoxy-coated reinforcement had been noted. Given these instances, there was a need to examine the potential for corrosion of epoxy-coated reinforcing steel in all highway bridges under a variety of environmental conditions.

The research project was designed to (1) determine the reasons for unsatisfactory corrosion performance of epoxy-coated reinforcing steel, (2) determine where it has occurred in highway bridges, and (3) make recommendations for improvements to current practice and specifications. The researchers reviewed the history of the development and use of epoxy-coated reinforcement in concrete structures, examined the practices involved in the production and application of epoxy-coated reinforcement, assessed field samples of existing bridges, and conducted laboratory evaluations of various testing techniques to predict long-term performance. Recommendations were made to improve the use of epoxy-coated reinforcing steel.

This research contract is complete; however, specimens used in the laboratory evaluations of testing techniques will be maintained by Florida Atlantic University under NCHRP Project 10-37A. Although some specimens have been destroyed and the findings included in this report, the NCHRP agreed with the researchers that it would be beneficial to extend the monitoring of the remaining laboratory specimens.

The research results from this contract have been published as NCHRP Report 370, "Performance of Epoxy-Coated Reinforcing Steel in Highway Bridges." Specification writers and materials, design, and construction engineers concerned with reinforced concrete structures will be interested in the findings from this research.

To create a link to this page, use this URL: http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=248