Influence du rapport E/C sur l'hydratation, la microstructure et les déformations endogènes de pâtes de ciment durcies

This work deals with the influence of the W/C ratio on the cement hydration and on the chemical characteristics and the microstructure of hydrated compounds. Results obtained with various techniques show that the W/C ratio has a significant influence on the structural characteristics of the hydrated cement pastes. Whatever the time of hydration, it appears that the materials have a different behaviour when W/C is higher than 0.40. This limit could correspond to a “percolation threshold” of water within the capillary pore network. When W/C increases, the amount of calcium hydroxide, referred to a unit mass of initial cement, increases whereas the CaO/SiO2 of C-S-H has a tendency to decrease. Moreover, for the autogenous deformations recorded during hydration, a swelling phase is exhibited before shrinkage phase with high W/C ratios. In the case of low W/C ratios, only shrinkage is observed.