Modeling the effects of microcracks on water permeability of concrete using 3D discrete crack network

In order to better understand the transport mechanism associated with the microstructural heterogeneity of cracked concrete composite, a modeling scheme is proposed and employed to assess the effects of microcracks on water permeability of concrete. Numerical samples containing 3D discrete crack network (unpercolated and percolated) with different geometric parameters (including crack density, width, length and roughness) are generated to represent the cracked concrete composite, and the effective permeability is estimated using finite element method (FEM). Extensive numerical simulations for more than 8600 concrete samples are carried out to extract the effects of microcracks on the water permeability. The results indicate that crack percolation is a determinant factor for increasing the transport properties of concrete. In addition, for concrete composite with unpercolated crack network, the influential factors to water permeability are crack density and length, while the effect from crack width is negligibly small; and for the percolated case, crack density, width and roughness are more closely correlated with the permeability of cracked composite.