Permeability prediction of hydrated cement paste based on its 3D image analysis

Abstract

Porous volume of hydrated cement paste is an important passage of fluid transport and thus needs to be characterized, aiming to predict its permeability, analyze its fluid mechanism and evaluate its contribution to fluid transport of cement-based materials. First, hydrated cement paste is applied to FIB/SEM (Focused Ion Beam) observation, REV (Representative Element Volume) analysis and pore size characterization. Then, we apply Katz-Thompson Equation and LBM (Lattice Boltzmann Method) to predict its permeability based on 3D porous volume, respectively. Finally, the influence of pore size on fluid transport of hydrated cement paste is analyzed and further discussed. Results show that single FIB/SEM sample can hardly be representative of hydrated cement paste. CPSD (Continues Pore Size Distribution) gives proper pore size distribution of hydrated cement paste, which is underestimated by MIP (Mercury Intrusion Porosimetry) and simulated MIP. LBM provides more details than the prediction of Katz-Thompson equation and gives a permeability in the range of 0.7–5.7 × 10−18 m2. Analysis of pore size effect shows that the medium and large capillary pores of 50–150 nm have great influence on the permeability and thus are the main passage of fluid transport in hydrated cement paste.