Thermodynamic investigation of the CaO-Al[sub 2]O[sub 3]-CaCO[sub 3]-H[sub 2]O closed system at 25 C and the influence of Na[sub 2]O

The solubilities of calcium hemicarboaluminate, calcium monocarboaluminate and calcium tricarboaluminate have been determined and the equilibrium phase diagram for the CaO-Al[sub 2]O[sub 3]-CaCO[sub 3]-H[sub 2]O closed system at 25 C has been calculated. Six isothermally invariant points have been located involving six stable hydrates: CH, C[sub 3]AH[sub 6], AH[sub 3], calcium hemicarboaluminate, calcium monocarboaluminate and calcite. Calcium tricarboaluminate, the carbonate analogue of ettringite, does not appear to be stable at 25 C. This study was part of a larger study on radioactive waste solidification.

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