Simulation analysis of microstructure development of tricalcium silicate using the needle model of calcium silicate hydrate

Abstract

This study proposes a two-scale model for tricalcium silicate (C₃S) hydration to examine the microstructure of hydrated C₃S paste. The needle-like morphology of a calcium silicate hydrate (C-S-H) layer, as observed in many studies, was constructed using this model based on the assumption of C-S-H needles. The boundary nucleation and growth pattern of the C-S-H needles were illustrated, and the impingement among C-S-H needles and particles was considered. The pore size distribution was calculated using the rolling sphere method for the hydrated particle system and C-S-H layer. The simulation results were compared with existing experimental data, revealing consistency for the C₃S paste with different hydration times. The shape and growth parameters of the C-S-H needles were studied to model their microstructure. The microstructure constructed using this model was found to be more reasonable and could provide a more accurate description of the C-S-H morphology.