Cathodic protection in reinforced concrete structures affected by macrocell corrosion: a discussion about the significance of the protection criteria

Cathodic protection is a technique that has been used to control corrosion and increase the service life of reinforced concrete structure. Standards as EN ISO 12696 give protection criteria for both impressed current and sacrificial anodes techniques, based on potential value or decay during a depolarization sequence. The polarization (current ON) and depolarization (current OFF) is experimentally studied on a corroded concrete wall thanks to six references electrodes and compared to a time-dependent modelling using FEM software COMSOL Multiphysics. Both experimental and numerical results show significant differences in the time response according to electrode location. This conclusion indicates that the concept of protection criteria defined by the standards is not suitable to assess the efficiency of cathodic protection applied to reinforced concrete structure.