Pore-scale modelling of 3D moisture distribution and critical saturation in cementitious materials

Abstract

The understanding and prediction of moisture distribution and critical moisture content above which fluid and ion transport can occur in porous media is of significant technological importance. A novel computational methodology for simulating moisture distribution and calculating critical content in 3D images of microstructures is presented. The method accounts for the liquid–gas interaction and liquid/gas–solid interaction at the pore scale. Microstructures of cement pastes at different curing ages, obtained by high-resolution X-ray micro-computed tomography, are analyzed. The equilibrium moisture distribution in the 3D microstructures is acquired. The degree of connectivity of the liquid and gas phases is calculated as a function of water saturation level. The critical water saturation for each phase is obtained. It is shown that the moisture distribution and connectivity of each phase depend strongly not only on the degree of water saturation but also on the structures of the pore space and the solid phase. The critical water saturation increases with the decrease of porosity. The results from the simulations are in very good agreement with the experimental data reported in the literature. The proposed methodology is applicable to image-based modelling of all porous media.