Numerical simulation of the effect of cement particle shapes on capillary pore structures in hardened cement pastes

Cement powder shapes have a pivotal role in particle packing and microstructural development, while its effect on capillary pore structure formation in three-dimension has not been fully understood. In this study, the modified CEMHYD3D model building on previous work of irregular-shaped cement particles is firstly used to simulate the evolution of capillary pore structures in cement pastes at various water-to-cement ratios. Pore networks at different curing time and degree of hydration are extracted and visualized. Subsequently, some home-made programs for determining three-dimensional pore structure characteristics including porosity, pore size distribution, pore connectivity and pore tortuosity are carried out on these simulated pore network extractions in hardened cement pastes. The results indicate that shape-induced larger surface area in more non-equiaxed irregular-shaped cement particles can improve pore structure parameters in hardened cement pastes, but this effect will be slight in the later curing period and at a low water-to-cement ratio. In addition, the less considered geometric difference plays a role in pore structure evolution especially for extremely non-equiaxed cement particle. However, the geometric attribute has a weak effect on pore structure parameters overall. It can also be concluded that the pore-to-solid ratio is still the most pronounced influence factor for pore structure parameters in hardened cement pastes.