Textural and mechanical characterization of C-S-H gels from hydration of synthetic T1-C₃S, β-C₂S and their blends

The textural and mechanical characterization of C-S-H gels formed from the hydration of pure T1-C₃S, β-C₂S and their blends are studied by Nitrogen sorption and nanoindentation experiments. The surface area and nanoporosity of C-S-H gels formed from the hydration of β-C₂S and the 30-70 (T1-C₃S and β-C₂S mixture) are higher than those from hydration of T1-C₃S, and 70-30, with the difference decreasing with hydration age. Such changes are well supported by findings of nanoindentation study, which shows the greater relative volume of C-S-H phases with lower densities in the β-C₂S and the 30-70 pastes. With the increase in hydration age, the relative volume of C-S-H phases with higher densities increased at the expenses of those with lower density. Important quantitative correlations were found among these textural characteristics and the mean chain length, determined from 29Si magic-angle-spinning (MAS) NMR, of the C-S-H gels.