Microstructure-based modeling of permeability of cementitious materials using multiple-relaxation-time lattice Boltzmann method

Due to its importance on the durability assessment and service life prediction of reinforced concrete structures, it is essential to estimate the permeability of cementitious materials. This paper presents a microstructure-based permeability modeling of cementitious materials using lattice Boltzmann (LB) method, where a multiple-relaxation-time (MRT) collision operator is used. The implementation and accuracy of the MRT-LB model is verified against the analytical and theoretical solutions of velocity profile and permeability for simple geometries. After verification, the MRT-LB model is applied to simulate the fluid flow in saturated cement paste. The microstructure of cement paste is generated by HYMOSTRUC3D. Following the onset of steady-state flow, the overall mean velocity is obtained and the water permeability is calculated according to Darcy’s law. The effects of water-to-cement (w/c) ratio, degree of hydration, curing age and effective porosity on the water permeability of cement paste are evaluated. The simulations are validated with experimental data obtained from literature. The results indicate that the simulated permeability is close to the measured permeability for the specimens at early age. In addition, for both simulation and experiments, the relationship between the permeability and effective porosity is highly correlated. This implies that the effective porosity is a critical parameter which determines the permeability of cementitious materials.