Maria Georgescu

Hydration process in 3CaO.SiO2-silica fume mixtures

Abstract The hydration process and hydrate compounds formed in the C3S-silica fume mixtures, were investigated using thermal analysis and BET specific surface determinations. Polymerization of silicates anions in the calcium silicate hydrates was studied using the molybdate method. The addition of silica fume to C3S, increases the kinetics of hydration-hydrolysis, for short periods of time (one day). An increase of Type I calcium silicate hydrates proportion was observed. The results of the molybdate complex method confirm that the presence of silica fume in a hydrating system influences the kinetics of the silicate anion polymerization process because of its pozzolanicity.

THE STUDY OF 'DSP' BINDING SYSTEMS BY THERMOGRAVIMETRY AND DIFFERENTIAL THERMAL ANALYSIS

The so-called DSP (Densified Systems containing homogenously arranged Particles) systems represent a high-performance class of inorganic binders. The hydration and hardening processes of some DSP systems, based on calcium silicates (C3S and C2S) or Portland cement/clinker with silica fume additions, were assessed, in this paper, using the thermogravimetry (TG) and differential thermal analysis (DTA). These data permit a qualitative and quantitative study of the formed hydrates as well as the estimation of hydration process kinetics.

Highly reactive dicalcium silicate synthesised by hydrothermal processing

Abstract The paper brings information concerning the synthesis and reactivity of a highly reactive dicalcium silicate using calcium silicate hydrates as precursors. The calcium silicate hydrates were prepared by hydrothermal treatments of mixtures consisting in CaO, amorphous SiO2 (ROMSIL) and water, under various hydrothermal conditions. C2S was obtained by thermal treatment – at low temperatures (700–800°C) – of these silicates hydrates. Due to this way of processing (hydrothermal synthesis and low temperature treatment), the dicalcium silicate obtained is very reactive and develops good compressive strengths in pressed mortar specimens even after one day of hardening.