Molecular dynamics simulation investigation on the anti-freezing mechanisms of CSH-GS/GO interfaces

Although graphene sheet (GS) and graphene oxide (GO) are two popular additives for improving the frost resistance of concrete, unclear anti-icing mechanisms of GS/GO cross-linked on the surface of calcium silicate hydrate (CSH) has hindered the design of concrete with higher durability in cold regions. To address this issue, we perform molecular dynamics simulation to reveal the icing processes of CSH-GS/GO interfaces. It is found that CSH-GS/GO interfaces can greatly suppress the crystallization process of ice compared to the original CSH surface. The crystallization process significantly weakens the chemical connectivity between CSH and GO, leading to the separation between them and ultimately the inhibition of icing. Massive H-bonds between CSH and GO disrupt the crystallization process, which is considered as the original cause of inhibition. Additionally, freezing of the solution drives salt ions to the surface of GO sheets. The existence of weak limited water (WLW) in the critical unfreezing region is resulted from the dynamic behaviors of nanosheets and ultra-high ions concentration. This work reports the ice regulation with GS/GO and opens a new avenue for the application of 2D nanomaterials in promoting anti-freezing ability of cement-based materials.