Prediction of mass transport in cracked-unsaturated concrete by mesoscale lattice model

The ingress of mass in a harsh chloride environment leads to the corrosion of reinforcing steel bars and deterioration of the structural performance. This paper deals with a two-dimensional (2D) numerical model for water and chlorides transport in the cracked-unsaturated concrete on the mesoscale level, in which concrete is modeled as a composite material with impermeable coarse aggregates embedded in the porous matrix which is separated by vulnerable interfacial transition zone (ITZ). Coupled with the unsaturated flow theory and the cubic law of water through a single crack, the transport coefficients for water and chloride ions in a single crack are developed by treating the crack as a parallel-plate configuration. The lattice network developed on the basis of Voronoi tessellation is presented to investigate mass transport process in the cracked-unsaturated concrete subjected to drying-wetting (D/W) cycles. The above proposed transport model coupled with the mesoscale lattice approach is validated by comparison with the available experimental findings from the literature. The numerical results indicated that the computational models are able to well represent the mass (water and chloride) movement within the cracked-unsaturated concrete. Furthermore, the cyclic D/W action and crack width/length within concrete are crucial for the transport properties of unsaturated concrete.