To meet the challenge of the new design life of 100 years for major concrete bridges in the U.S., economical and corrosion resistant reinforcing bars will be needed. Preliminary data from an investigation funded by the U.S. Federal Highway Administration that was aimed at identifying reinforcing bars that will have better performance than the current epoxy-coated bars had suggested that stainless steel clad bars could be such a bar. For the purpose of verifying those results, the behavior of clad bars in test concrete blocks that were subjected to weekly cycles of ponding with a saturated salt solution and drying was compared with those of three solid stainless steel (316LN, 304, and 2205) bars and the traditional carbon steel bars. The behaviors of these bars were monitored by regular measurements of the macrocell current, corrosion rate, and open- circuit potential, made throughout the first 700 days of exposure. The data indicated that the clad bars exhibited practically the same good corrosion resistance as the three solid stainless steel bars did. While the carbon steel bars had started to corrode even after just 90 days of exposure, the clad bars and all the other bars have yet to show any discernible corrosion activity even after 700 days. Comparison of the estimated chloride concentrations in the concrete blocks at these two time benchmarks indicated that the clad bars and the stainless steel bars were able to tolerate at least 15 times more of the corrosive chloride ions than the carbon steel bars did.
Key Words: Concrete bridges, corrosion of reinforcing bars, stainless steel bars, carbon steel bars, clad steel bars