Polarization behavior of activated reinforcing steel bars in concrete under chloride environments

Polarization behavior of activated reinforcing steel bars (rebars) in concrete was investigated by use of measured cathodic polarization curves. Five factors thought to contribute to the polarization behavior of rebars in concrete were examined, including relative humidity, Cl⁻ content, rebar diameter, water-cement ratio and corrosion duration. The Levenberg-Marquardt curve-fitting algorithm made it possible to determine the corrosion rate and electrochemical parameters of underlying anodic and cathodic sub-process simultaneously. Degrees of activation polarization and concentration polarization related to cathodic reaction were quantified. A prediction model for the average value of corrosion rate in regard to the whole surface of a corroded rebar was proposed based on the electrochemical corrosion theory. Finally, the accuracy of this model was testified by comparing the predictions of this model with published corrosion test results.