The System CaO‐Al ₂ O ₃ ‐H ₂ O

Abstract

Phase equilibria have been determined in the system CaO‐Al 2 O 3 ‐H 2 O in the temperature range 100° to 1000°C. under water pressures of up to 3000 atmospheres. Only three hydrated phases are formed stably in the system: Ca(OH) 2 , 3CaO·Al 2 O 3 ·6H 2 O, and 4CaO·3Al 2 O 3 ‐3H 2 O. Pressure‐temperature curves delineating the equilibrium decomposition of each of these phases have been determined, and some ther‐mochemical data have been deduced therefrom. It has been established that both the compounds CaO·Al 2 O 3 and 3CaO·Al 2 O 3 have a minimum temperature of stability which is above 1000°C. The relevance of the new data to some aspects of cement chemistry is discussed.