Source data of cement hydration inhibition by silane coupling agents elucidated from atomistic simulations and hydration experiments

Silane coupling agents are widely recognized to retard early hydration when incorporated into fresh cement paste, yet the atomic-level mechanisms underlying their effects on clinker dissolution, such as the adsorption of silane monomer onto reactive surface sites and the modification of ion detachment pathways, remain largely unexplored. Here we show dissolution pathways of tricalcium silicate (Ca₃SiO₅) under 3-aminopropyl triethoxysilane impact using <i>ab initio</i> metadynamics, with subsequent experimental validation of the retardation effects in silane-treated pastes. The shielding effect of silane induces a shift in the free energy changes of stepwise calcium dissolution from negative to positive and alters the most stable coordination state of calcium during dissolution, resulting in the transition of calcium dissolution from spontaneous to non-spontaneous. Specifically, hydrolyzed silane monomer dissociatively adsorbs onto Ca₃SiO₅ surface by forming ionic Ca-O bonds, thereby occupying reactive sites and introducing steric hindrance. This, in turn, impedes coordination between calcium ions and water molecules. Experimental results further corroborate these interactions, as evidenced by reduced calcium concentrations in silane-treated pastes, which in turn slowed hydration process. These findings offer nanoscopic insights into the role of SCAs in cement hydration and provide a foundation for future research into the complex interactions within organic/cement systems.