Prediction model for the time-varying corrosion rate of rebar based on micro-environment in concrete

The corrosion rate of rebar in concrete is time dependent, and calculation of this rate is very important in predicting corrosion cracking and the corresponding service life of the rebar. In the present paper, the controlling factors of the corrosion rate of rebar in concrete under atmospheric environment were first analyzed, and conclusion for joint control of cathode and anode activation polarizations was drawn. Based on the corrosion dynamic equations under activation polarization control, an electrochemical fundamental model for the corrosion rate of rebar was established. Then, based on this model and the test results on the corrosion of rebar in concrete and the resistivity of concrete under artificial climate environment, a prediction model for the corrosion rate of rebar was presented comprehensively, which takes into account the effects of the concrete’s micro-environment and corrosion time. Finally, feasibility of the prediction model was verified through comparisons between the predicted and measured values both under artificial and natural climate environment.

► Corrosion rate of rebar is controlled by activation polarizations under atmosphere.
► Electrochemical fundamental model for corrosion rate of rebar in concrete is built.
► Prediction model for the time-varying corrosion rate of rebar in concrete is built.