Numerical simulation of effective diffusivity in concrete with random microcracks

Abstract

Cracks in concrete structures can provide preferential transport pathways for the ingress of aggressive media. Therefore, it is important to understand the relationship between cracks and the durability properties of concrete. Numerical modeling is an efficient and practical means of investigating the effect of cracks, especially microcracks, on the diffusivity of concrete. In this study, a modeling scheme was developed to predict the effective diffusivity of cracked concrete. Numerical samples containing randomly overlapping and nonoverlapping microcracks were generated, and the effects of microcrack geometrical parameters were investigated. The results showed a critical area fraction of microcracks in the diffusion process, which was related to the aspect ratio, orientation, and tortuosity of microcracks. The effective diffusivity was found to be closely related to the crack orientation and tortuosity. Moreover, the tortuosity of nonoverlapping microcracks was observed to be greater than that of overlapping microcracks at the same area fraction.