Simulation of chloride ion transport in concrete under wetting–drying cycle

In the corrosive environment of chloride, the drying–wetting alternating zones are most seriously eroded by harmful media. Firstly, based on the new porosity and tortuosity model, considering the interaction between the transport of water and the tortuosity in the concrete microstructure, a nonlinear diffusion–convection model of water is established. Secondly, a two-dimensional variable coefficient model of chloride ion transport in concrete under the coupled effects of drying–wetting cycles is established based on Fick’s second law. The main parameters influencing transport in the proposed model such as porosity, tortuosity, saturation of concrete and hydration degree of cement are fully considered. Finally, the model is numerically solved by the alternating direction implicit (ADI) method. The results show that the values predicted agree with those of experiments.