Based on the analysis of chloride ion-induced erosion mechanism of reinforced concrete and the Fick’s second law

a multi-factor model of the chloride ion erosion is established. In this model

the influences of water-cement ratio

humidity

time

temperature

and chloride ion binding capacity of concrete are taken into consideration

and the mathematic solution to the new model is provided by considering the boundary conditions. The new model is verified by analyzing the long-term exposed experiment data. Compared with the traditional model of Fick's second law

the model can indicate the development trend of the structure eroded by chloride and the chloride ion concentration in different depth

and at the same time

it can predicate the chlorine ion concentration on rebar surface in different corrosion periods and the initiation corrosion time of reinforcement.