Hydrothermal characteristics of high-slag cement pastes made with and without silica sand

High-temperature steam curing of different cementitious materials is almost always associated with building products having improved physicomechanical and binding characteristics. The properties of these autoclaved products are always governed by the chemical composition and physical state of the formed hydration products which act as the main binding centres. In the present study, high-slag cement (HSC) and HSC-ground sand (GS) specimens were hydrothermally treated at pressures of 8 atm of saturated steam for different autoclaving periods. Compressive strength tests were done on the hydrothermally hardened specimens; then hydration kinetics, phase composition and microstructure of the formed hydrates were studied using the ground, dried samples. The results of compressive strength could be related to the phase composition and microstructure of the formed hydration products. These results were also explained on the basis of reactivity of both HSC and GS towards the hydrothermal reaction.