Testing of Selected Metallic Reinforcing Bars for Extending the Service Life of Future Concrete Bridges: Testing in Outdoor Concrete Blocks

About the report:

To meet the challenge of a design life of 100 years for major concrete bridges, economical and corrosion-resistant reinforcing bars will be needed. The preliminary results for stainless steel-clad bars in a recent investigation funded by the Federal Highway Administration suggested that stainless steel-clad bars could quality. To verify these results, this investigation compared the behavior of clad bars, three solid stainless steel (316LN, 304, and 2205) bars, and the traditional carbon steel bars in test concrete blocks exposed to weekly cycles of ponding with a saturated salt solution and drying. Regular measurements of electrochemical parameters such as macrocell current, corrosion rate, and open-circuit potential throughout the first 700 days of exposure indicated that the clad bars and the three solid stainless-steel bars have virtually the same excellent resistance to corrosion. Whereas the carbon steel bars started to corrode after only 90 days of exposure, the other bars did not evidence any discernible corrosion activity, even after 700 days. A comparison of the estimated chloride concentrations at 90 and 700 days indicated that the clad bars and the stainless-steel bars could tolerate at least 15 times more corrosive chloride ions than could the carbon steel bars.

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