Lattice Boltzmann simulation of permeability of cement-based materials

Abstract

Due to its importance on the durability assessment and service life prediction of reinforced concrete structures, it is essential to estimate the permeability of cement-based materials. This paper presents a microstructure-based permeability modeling of cement-based materials using the lattice Boltzmann (LB) method, where a multiple-relaxation-time (MRT) corrosion operator is utilized. The MRT-LB model is applied to simulate the single-phase 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. In the numerical experiments, the effects of water-to-cement (w/c) ratio, degree of hydration and effective porosity on the water permeability of cement paste are evaluated. The simulations are validated with experimental data obtained from the literature. The results indicate that the simulated permeability is close to the measured permeability for the samples at early age. For the samples with effective porosity higher than 20%, the simulation shows a good agreement with the experiment. In addition, for both simulation and experiments, the relationship between the water permeability and the effective porosity is highly correlated. This implies that the effective porosity is a critical parameter which determines the permeability of cement-based materials.