Civil Engineering Association

PERFORMANCE EVALUATION OF VARIOUS CORROSION PROTECTION SYSTEMS OF BRIDGES IN COLORADO

Corrosion of reinforced concrete structures has been a significant problem for many state and transportation agencies since the application of deicing salts was introduced. Much research has been conducted to develop corrosion protection systems that can prolong the life span of reinforced concrete structures. CDOT has several routine and experimental measures to prevent corrosion of the rebar including epoxy-coated rebar, calcium nitrite admixture, organic corrosion inhibitors, a thick cover of quality concrete, and a waterproofing membrane covered by an asphalt overlay.
An extensive literature review was performed to collect information on various corrosion protection systems that have been used in the U.S. and around the world. Current CDOT practices in terms of corrosion protection measures were reviewed. A draft inspection plan for Colorado’s bridge structures was proposed. This plan could be further refined in the future to evaluate the performance of routine measures and experimental measures for corrosion protection. Field inspections were conducted for two sets of bridges (total of 16 bridges). One set is for evaluating the corrosion damage in some bridges in the TREX project (a major ongoing highway project in the Denver area), and the other set is for the inspection of various corrosion protection systems that have been used in Colorado. The seven TREX bridges inspected in this project used three corrosion protection methods: epoxy-coated rebar, asphalt overlay, and membranes. Corrosion of steel and corrosion-induced damage in concrete occurred in all bridges except the Dry Creek Bridge, which is relatively new. The degree of corrosion is quite high. Nine other bridges with different corrosion protection systems were inspected to study the effectiveness of these protection methods.
Based on the inspection results, we can conclude that, in general, corrosion of steel bars in concrete is an existing problem for highway bridges in Colorado. The extent of the problem is quite significant. Among the three most commonly used protection systems (epoxy-coated rebar, corrosion inhibitors, and membranes), the results obtained in the present study are inconclusive for determining which system is better.