Simulation analysis on hydration kinetics and microstructure development of tricalcium silicate considering dissolution mechanisms

Abstract

Dissolution mechanisms are used to explain the dissolution of tricalcium silicate (C3S) in cement hydration. The change of solution undersaturation activates different mechanisms and eventually induces the anisotropic dissolution which plays a crucial role in the microstructure development and hydration kinetics. The dissolution is simply considered as isotropic. Therefore, the influence of dissolution mechanisms on the hydration of C3S cannot be considered in numerical models. Furthermore, the influence of the combination of different dissolution mechanisms on the microstructure development and hydration kinetics of C3S is poorly understood. The purpose of this study was to analyze the influence of different combinations of dissolution mechanisms on the microstructure development and hydration kinetics of C3S, and to provide a new method for improving the existing hydration numerical models. Therefore, the influence of the combinations of different mechanisms on the microstructure development and hydration kinetics of C3S was analyzed and a new simulation method was proposed for simulating the dissolution mechanisms of C3S. The analysis results indicated that: (1) the integral absolute error result of the degree of hydration for the “classical” dissolution mode (CDM), anisotropic dissolution mode A (ADM-A), and anisotropic dissolution mode B (ADM-B) was 7.1%, 4.6%, and 8.2%, respectively; (2) the ADM-A would transform into the CDM when the particle was covered by the etch pits; (3) the time needed for the dissolution mode transformed from the ADM-A into the CDM, and from the ADM-B into the CDM depended on the dislocation density and the nucleation probability of two-dimensional vacancy islands, respectively; (4) the evolution of the degree of hydration obtained from the ADM-A and ADM-B depended on the dislocation density and the nucleation probability of two-dimensional vacancy islands, respectively; (5) the evolution of the hydration rate obtained from the ADM-A and ADM-B could be explained by the evolution of the reactive surface area and the interfacial dissolution rate.