Modelling the coupled evolution of hydration and porosity of cement-based materials

A modelling of the relationship between the evolution of endogenous hydration and that of porosity of cement-based materials was carried out. The mass balance equations of anhydrous and hydrates were written in molecular scale, then, transposed in macroscopic scale by using the volume averaging technique. The combined system of obtained equations (porosity equation and macroscopic mass balances) was solved numerically. The model validation was done in two steps in the case of two mortars cured during 2, 7 and 21 days. Simulation results of hydration rates were compared to the experimental results obtained by SEM images analysis and the theoretical evolution in time of the porosity was checked against MIP results. Globally, a good correlation between simulation results and experimental ones was noticed. However, to less disturbing the hydration process of the material, it seems desirable to improve the drying mode of the samples before SEM analyses or MIP tests.