Initial hydration process of calcium silicates in Portland cement: A comprehensive comparison from molecular dynamics simulations

As the main components of Portland cement, calcium silicates show substantial differences in their hydration reactivity which have not been fully explained. A comprehensive comparison of the initial hydration process of calcium silicates, namely dicalcium silicate (C2S) and tricalcium silicate (C3S), was conducted using molecular dynamics simulations. The initial hydration process was divided into three stages using cut-off times of 0.001 ns and 3 ns. The hydration of M-3-C3S (010) was more evident than that of beta-C2S (100), supported by the hydroxylation degree, radial distribution function, atomic density profile, etc. The coordination number of the surface Ca atoms might be the underlying reason for such a difference. Interactions between cement surfaces and water molecules were mainly characterised by solid O-H bonding and Ca-water O bonding. Dissolution of Ca atoms was observed, although quite scarce, while no dissolution of Si atoms was observed.

Automated summary

A comprehensive comparison of the initial hydration process of calcium silicates, namely dicalcium silicate (C2S) and tricalcium silicate (C3S), was conducted using molecular dynamics simulations. It was found that the hydration of M-3-C3S was more evident than beta-C2S, possibly due to the coordination number of the surface Ca atoms. Interactions between cement surfaces and water molecules were mainly characterized by solid O-H bonding and Ca-water O bonding.