Enhanced corrosion resistance of reinforcing steels in simulated concrete pore solution with low molybdate to chloride ratios

The effect of molybdate on corrosion resistance of the conventional low-carbon reinforcing steel (LC steel) and a Cr-bearing reinforcing steel (10% Cr steel), when exposure to saturated Ca(OH)(2 )solution simulating concrete pore environment with low molybdate to chloride ratios, was investigated by using various electrochemical measurements and surface characterization techniques. The results show that a small amount of molybdate could delay the corrosion process of both steels effectively in the presence of high chloride concentration, and the improved inhibition efficiency is highlighted with increasing molybdate to chloride ratio from 0.01 towards 0.1. In addition, it is further confirmed that, in the condition of alkaline solution with high chloride concentration, 10% Cr steel has significantly higher corrosion resistance than LC steel, regardless of molybdate. Based on a comprehensive analysis on these results, the inhibition mechanisms of molybdate for both steels are proposed in chloride-contaminated alkaline concrete pore solution.