Determining hydration mechanisms for initial fall and main hydration peak in tricalcium silicate hydration using a two-scale hydration simulation model

Abstract

This study aimed to determine the hydration mechanisms of the initial fall and main hydration peak in tricalcium silicate (C3S) hydration using a two-scale hydration simulation model. The model could consider the coalescence of etch pits, the dependence of the interfacial dissolution rate on solution undersaturation, and the boundary nucleation and growth of calcium silicate hydrate (CSH). The results indicated that (1) the dissolution theory could reproduce the initial fall of the hydration rate in C3S hydration; (2) when only the dissolution theory was considered, a discrepancy in Si concentration at the very early age of hydration was found between the results obtained from simulation and experiment; and (3) the main hydration peak could be ascribed to the combined effect of the dissolution of C3S with the coalescence of etch pits, the nucleation and growth of CSH, and the shrinkage of particles.