Solubility of tricalcium aluminate from 10 °C to 40 °C

Abstract

Fundamental reaction-transport models of Portland cement hydration have been difficult to refine and validate because of the challenge of obtaining accurate data on the reaction rates and solubility of the four major clinker phases. Here we provide the first measurements of the solubility product of cubic tricalcium aluminate (C3A) as a function of temperature between 10 °C and 40 °C. The measurements were obtained by examining dissolution rates as a function of solution saturation and extrapolating the lowest dissolution rates to zero by nonlinear regression. That procedure yields ln Ksp(C3A), for the dissolution: C3A + 2H2O = 3Ca2+ +2AlO2− + 4OH−, of −43.74, −48.02, −49.48 and −50.56 at temperatures of 10 °C, 20 °C, 30 °C and 40 °C, respectively. These Ksp data were regressed to several candidate temperature models used in thermodynamic modeling to estimate the functional dependence of the standard Gibbs energy of dissolution on temperature. The results can be used to refine thermodynamic models of cementitious materials and related simulation approaches for predicting microstructure development of concrete binders.