Water dissociation and hydrogen penetration in C3S hydration from DFT and molecular dynamics simulations

XG Lin and WJ Wang and Y Ren and B Li and Y Zhang and JY Zhang and Y Zhang, THEORETICAL CHEMISTRY ACCOUNTS, 144, 55 (2025).

DOI: 10.1007/s00214-025-03212-6

The hydration of C3S controls mechanical properties and rheological performances of cement. To date, there has been rare fundamental understanding of C3S hydration at the atomic level. In this work, DFT and MD method are used to present a complete picture of water dissociation and hydrogen penetration in C3S hydration. The results show that water prefer to dissociate at ionic O atoms on the surface, forming a hydroxyl group and a H atom. As water coverage increasing, the H atom penetration becomes exothermic and easier, the reducibility of inner layer O atoms increases, which is attributed to the changed CBM of O atoms of inner layer. The results of MD simulation show a "H passivation layer" after 2300 ps of hydration process in the hydrated C3S structure; the dissociated H atoms penetrate the inner layer of C3S forming H-w-O-s bonds, preventing the further penetration of H atoms. We believe this work lays groundwork for durability design of cement concrete and give a new insight of interfacial modifications in cement hydration.

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