Phase equlibria in the CaO — Al₂O₃ — SiO₂ — H₂O system at 5°C, 20°C and 38°C

Gehlenite hydrate (C₂ASH₈) is the primary crystalline phase formed by the hydration of cements made by blending high-alumina cement with ground granulated blastfurnace slag. Phase relations in the CaO—Al₂O₃— SiO₂—H₂O system have been studied at 5°C, 20°C and 38°C to determine the likely stability of C₂ASH₈ in such cements. Some invariant-point compositions have been calculated using the solubility products obtained from the experimental results. These compositions have been used to identify the likely stable and metastable phase assemblages in the system. The compositions of siliceous hydrogarnets formed in the system have been determined.