A dehydration kinetic model of calcium silicate hydrates at high temperature

摘要

Dehydration of calcium silicate hydrates, the primary binding phase of cement paste, contributes significantly to the degradation of cementitious materials at high temperatures. Kinetics of the dehydration process is usually parameterized as the product of the classic Arrhenius equation and a kinetic expression, calibrating the influence of the temperature and the reaction degree, respectively. By means of the Exp-function approximation, an improved kinetic expression is proposed and the differential equation is solved by utilizing the Mean-value Theorem for integrals. The established dehydration model is validated by comparing with independent experimental measurements, concerning different heating regime and molar ratios of calcium-to-silicon. Both the temperature history and the calcium-to-silicon molar ratios influence the kinetics and the final status of the dehydration process. The established model provides access to further investigation of the microstructural evolution of heated concrete, containing supplementary cementitious materials.