Part 1: A study on the properties of synthetic hydroxyledgrewite

Abstract

In this work, for the first time chemical and physical properties of hydroxyledgrewite synthesized under hydrothermal conditions were examined. Hydroxyledgrewite was synthesized in the primary mixture consisted of CaO and amorphous SiO 2 ÁnH 2 O, when the molar ratio of CaO/SiO 2 was equal to 2.25. The synthesis has been carried out in unstirred suspensions under saturated steam pressure at 200°C temperature for 48 hours. It was proved that synthetic hydroxyledgrewite is stable till 675°C and at higher temperature recrystallized to c-C 2 S, a 0 L -C 2 S, while upon subsequent cooling transformed into b-C 2 S. In addition to this, it was also determined that the density and specific heat capacity at 25°C are equal to 2.668 AE 5 g/cm 3 and 0.928 J/(gÁK), respectively. Synthetic hydroxyledgrewite showed disordered aggregates of plate-like particles, while calculated S BET value is equal to 13.961 m 2 /g. According gas adsorption results, it was obtained that hydroxyledgrewite is a mesoporous material. Also, it was obtained that after 72 hours of activated hydroxyledgrewite hydration, the amount of released heat was equal to 74.34 J/g. The product of synthesis and calcination were characterized by XRD, STA, DSC, SEM, TEM, FT-IR analyses, and BET method. K E Y W O R D S calcium silicate hydrate, hydrothermal, microstructure, synthesis, thermal properties