Improving the adhesion properties of cement/epoxy interface using graphene-based nanomaterials: Insights from molecular dynamics simulation

The cement/epoxy interface is a critical component in a repair system. Normally, the adhesion properties of the epoxy coating are negatively affected by the presence of moisture or the ingress of harmful species to the interface. In this paper, the interfacial properties between the cross-linked epoxy and hydrated calcium silicate (C–S–H) using graphene (GR) and graphene oxide (GO) nanomaterials were investigated utilizing molecular dynamics (MD) simulation. Various reinforcement schemes were adopted, including adding the GR or GO layer and modifying the epoxy with GR or GO nanomaterials. In addition, three exposure systems (dry, wet, and salty) were considered. The results indicated that introducing a GO sheet at the epoxy/C–S–H interface enhanced the adhesion energy as the oxygen-containing functional groups in the GO provided better tight-binding patterns with the C–S–H surface as well as the epoxy overlay. Modifying the epoxy by GR nanosheet also increased the adhesion energy due to its suitably-oriented conformation inside the epoxy matrix. Moreover, the introduction of graphene reinforcement effectively mitigates the diffusion of moisture and chloride ions. The reported results will certainly enhance our understanding of the sustainability and durability of the epoxy-bonded concrete systems under aggressive moist and chloride environments.