Multi-scale peridynamic investigation of chloride penetration in concrete under drying-wetting cycles

A multi-scale peridynamic (PD) model was developed to simulate chloride penetrating process in concrete under drying-wetting cycles. The meso-structure characteristics of concrete and advection-diffusion were considered simultaneously. The governing equations of chloride penetrating during drying-wetting cycles was originally established under the framework of PD theory. Subsequently, the corresponding boundary conditions for wetting and drying process were constructed. The accumulative effect of chloride under drying-wetting cycles was taken into account with the superposition method. Numerical examples demonstrate that the multi-scale PD model is robust and efficient in capturing the variation of chloride concentration and relative humidity. The results show that with the approach to the exposed surface, the differentials of relative humidity rise significantly. The chloride concentration is affected by positions of reference points and relative humidity. Namely, it increases first and then decrease or remain constant during every drying-wetting cycle. Notably, the maximum chloride concentration occurs in a region adjacent to exposed surface rather than on the exposed surface, which coincides well with the experimental phenomenon reported in the literature.