Probing the dynamics of water over multiple pore scales in cement by atomistic simulations

Abstract The presence of water in hydrated cement has significant effects on the properties of concrete. However, direct correlation of water with the macroscopic properties of concrete remains a major challenge. In this study, we use molecular dynamics simulations to determine the water dynamical properties in four pore environments of the calcium silicate hydrate (C–S–H) colloid model; interlayer pores, gel pores, connected pores and in the vicinity of a finite disk–like globule particles. It was revealed that the translational and rotational dynamics are decoupled, consequently, the translational dynamics govern the calculated T2 relaxation time at the surface. Based on NMR T2–T2 relaxation investigation, we showed an exchange between 1 and 4 nm connected pores. At short times, the adsorption/desorption of water from a 1 nm pore is limited to the edges, a behavior linked to water sorption hysteresis. The properties of water in the proximity of a finite C–S–H globule and confined in infinite pore models are comparable.