Pore-scale chemo-mechanical modelling of leaching in ordinary Portland cement

Numerical homogenization, random dissolution model and direct reactive transport simulation based on pore scale Lattice Boltzmann method were applied to simulate microstructure evolution of ordinary cement paste upon leaching. The obtained microstructures were used to estimate the elastic moduli as function of the Ca-leached. For comparison, a simplistic approach was applied in which the leaching of CH and C–S–H were simulated randomly removing CH phase followed by removal of C–S–H. The estimated elastic moduli are then compared for different microstructure generation approaches and with volume-based homogenization approach. Comparison of reactive transport LB simulations of microstructure with random microstructure generation algorithm, suggest that at small degree of degradation the model predictions are rather close especially for the simplified scenario limited to CH leaching. The differences become more significant at the leaching level beyond 25%. The differences are related to the spatial distribution of LD C–S–H and HD C–S–H in the microstructural model. The calculated effective modulus of the cement paste with MT homogenization agrees very well with the numerical homogenization results for various degrees of CH dissolution and C–S–H dissolution, except at 100% CH dissolution where there is a noticeable deviation. The correspondence for the Poisson’s ratio between the two methods is also in excellent agreement. In particular, this study goes beyond the previous reactive transport modelling by considering kinetics of CH and C–S–H dissolution.