Critical Chloride Corrosion Threshold of Galvanized Reinforcing Bars

Determination is made of the chloride content required for galvanized reinforcing bar corrosion initiation. With the exception of there being no chromate treatment application so that the degree of hydrogen evolution for untreated bars could be evaluated, the bars conform to ASTM A767. There is comparison of bridge deck chloride surveys with test results, as well as with results for 316LN stainless steel, low carbon chromium (ASTM A1035, MMFX), and conventional (ASTM A615) reinforcement. There is a greater average galvanized reinforcement critical chloride corrosion threshold than for conventional steel. The threshold is lower when compared to ASTM A1035 and 316LN steel. Concrete porosity in the non-chromate treated bars did not increase through hydrogen gas evaluation relative to that observed for conventional reinforcement. Compared with 15 years for ASTM A1035 steel and 2.3 years for conventional steel, there is a 4.8 year average time to corrosion initiation for galvanized steel at bridge deck crack locations. There is no corrosion of 316LN stainless steel.