Molecular quantification of the decelerated dissolution of tri-calcium silicate (C₃S) due to surface adsorption

The C₃S hydration often experiences a slow-dissolving period (induction period) following the initial rapid dissolution. The mechanism of this phenomenon is unclear despite a century of study. Molecular dynamics (MD) simulation may provide atomic-scale evidence, but is often limited to short duration of simulation. To fill this gap, this paper explores an accelerated simulation scheme through raising temperature. Evolution of the C₃S (010) crystal plane in contact with water were simulated at 300 K, 500 K, 700 K and 1000 K. Configurations of water molecular, Si[sbnd]O and Ca[sbnd]O coordination were studied as a function of hydration time. The dissolution and adsorption of [Ca] and [Si] species were quantified to calculate the kinetics of each fundamental steps. The results confirm that rising temperature in our simulation scheme increases the reaction rate without alternating the configurations of species. It further enables observing the re-adsorption of dissolved species which correlates with a reduction of net-dissolution rate.