Electrochemical Methods for Judgment of Critical State of Reinforcement Corrosion in Concrete

An artificial climate experiment system was designed and established to study the reinforcement corrosion of concrete structures exposed to simulated marine environment. Electrochemical methods such as corrosion potential, linear polarization and electrochemical impedance spectroscopy were applied to study the reinforced steel bar corrosion threshold of ordinary portland concrete (OPC). The concrete specimens were cured for 14 days in a standard cure environment before placed in the artificial climate cabinet. The results show that the corrosion current density of reinforcing bar increases rapidly in a order of magnitude when the surface chloride concentration near the steel bar reaches the chloride threshold value for reinforcement corrosion. Both linear polarization and electrochemical impedance spectroscopy can be used to determine the corrosion threshold accurately.