Probing the early stages of hydration in dicalcium silicates at electronic level

beta-C2S and gamma-C2S are utilized for the development of low-carbon cementitious materials due to their low Ca/Si ratio, low production temperature, and great potential in CO2 capture and storage. During carbonation, the hydration state of the surface in the presence of water impacts the degree of carbonation. Therefore, this work investigated the initial hydration reaction behavior between beta-C2S and gamma-C2S through electronic property calculations, the ab initio molecular dynamics simulations, and well-tempered metadynamics simulations, from bulk to surface calcium ions dissolution. Research indicates that calcium ions with low symmetry and oxygen ions with high electron density are more reactive. Compared to the gamma-C2S (010) surface, the beta-C2S (100) surface exhibits stronger hydration reactivity. Simulations of calcium ion dissolution on surfaces have revealed the existence of different dissolution mechanisms for calcium ions on different surfaces. The aforementioned study facilitates a more profound comprehension of the initial hydration reactivity disparities between mineral phases.