Process for producing tobermorite and ettringite

TLDR: In this paper, a mixture of a lime material and a siliceous material containing 10 to 40% by weight of alumina is mixed with an alkali solution, and the mixture is subjected to hydrothermal reaction with saturated water vapor at 4 to 40 kg/cm2 to form tobermorite.

Abstract: A lime material and a siliceous material containing 10 to 40% by weight of alumina are admixed with an alkali solution, and the mixture is subjected to hydrothermal reaction with saturated water vapor at 4 to 40 kg/cm2 to form tobermorite. The reaction mixture is filtered to separate the tobermorite therefrom. A lime material and a gypsum material are added to the resulting filtrate, and the mixture is reacted at room temperature to a temperature of 90° C. to form ettringite. The alkali filtrate separated from the ettringite is reused for the production of tobermorite.