DISSOLUTION OF SPARINGLY SOLUBLE INORGANIC COMPOUND IN AQUEOUS SUSPENSION CONTAINING ION-EXCHANGE RESIN .8. HYDRATION PRODUCTS OF TRICALCIUM SILICATE (CA3SIO5)

A strongly acidic ion exchange resin, H-R, is a novel dissolution agent for sparingly soluble inorganic materials in aqueous media. The dissolution proceeds by cation exchange reaction between H-R and dissolved ion of minute quantities, which promotes further dissociation tendency of the material to achieve complete dissolution. In this study, the dissolution processes of the fully and the immature hydration products Of C3S in the presence of H-R were followed by the methods of the ion exchange titration,6) chemical analysis and calorimetric measurement. The fully and the immature hydration products were obtained by stirring C3S aqueous suspensions at 80-degrees-C for 3 days and 25-degrees-C for one night, respectively. The obtained restults are summarized as follows; (1) Complete hydration is achieved by stirring C3S suspension (W/S = 10) at 80-degrees-C for only few hours giving a mixture of Ca (OH) 2 and af-willite (C3S2H3). Addition of H-R into an aqueous suspension containing the mixture results in consecutive dissolution of both compounds accompanying distinct variations in pH, specific conductivity and calorimetric thermogram. Preferential reaction between Ca(OH)2 and H-R is due to higher solubility in H2O remaining afwillite, which is dissolved by further addition of H-R. The heat of dissolution of afwillite in H-R suspension at 25-degrees-C is measured to be 273.7 kJ/mol. (2) The degree of hydration and the amount of formed Ca(OH)2 of C3S suspension hydrated for one night are estimated to be about 60% and 0.75 mol/C3S-mol, respectively, by analyzing the results obtained by the ion exchange titration and the calorimetric measurement carried out by a small addition of H-R.