Effect of Cl^- on Corrosion Process of Rebar in Concrete

The corrosion rules of rebar steel in simulated chloride environments were studied by accelerating corrosion test of dry-wet cyclic immersion through measuring the corrosion weight loss of reinforcing steel and monitoring the change of pH value in the process of reinforcing steel corrosion. The results showed that the corrosion rate of rebar increased first and then decreased with the increase of Cl- concentration. With decreasing the pH value, the corrosion process of reinforcing steel passed the passivation area, depassivation area and activation area. In the depassivation area (pH =12.3～11), the corrosion rate of reinforcing steel increased rapidly. The decrease of pH value caused by reinforcing steel corrosion was much larger than that caused by the carbonation of Ca(OH)2.