Numerical study on effects of the degree of water saturation on ICCP of chloride-contaminated RC structures

The effect of the degree of concrete water saturation on impressed current cathodic protection (ICCP) of chloride-contaminated reinforced concrete (RC) structures was investigated using a numerical model that includes transport of oxygen and ions, electrode reactions, and steel polarization. The results indicate that the local current density and potential at the steel surface are significantly affected by the saturation degree. The risk of the hydrogen embrittlement of steel may rise in a voltage-controlled ICCP when the concrete saturation degree increases, and the applied voltage needs to be reduced in this case. For RC structures having a high saturation degree, ICCP has a stronger ability to increase the pH around the steel reinforcement and to remove Cl⁻. When the concrete saturation degree is low, the stationary numerical model based on the Laplace equation is recommended to investigate or design ICCP if neglecting its effect on the Cl⁻ removal and pH increase. When the concrete saturation degree is high, the time-dependent numerical model, including transport of oxygen and ions, electrode reactions, and steel polarization, is recommended.