Improving the impermeability of cement/epoxy coating interface by g-C3N5: A molecular dynamics study

YD Yao and FJ Tang and ST Yang and B Li, MATERIALS TODAY COMMUNICATIONS, 41, 110763 (2024).

DOI: 10.1016/j.mtcomm.2024.110763

The accumulation of chloride that penetrates through the concrete cover from the ambient environment is the primary factor contributing to the interfacial degradation between concrete and epoxy-coated steel rebar. In this study, a nitrogen-rich carbon nitride (g-C3N5) modified epoxy (EP) coating is proposed to enhance the impermeability of the concrete/epoxy interface. The local structure, dynamic characteristics, and impermeability mechanism of g-C3N5 inserted into the interface of concrete/epoxy coating during the penetration of NaCl solution are studied using the molecular dynamics method. It is found that the insertion of g-C3N5 at the concrete/ epoxy interface effectively slows down the penetration of NaCl solution. The g-C3N5 nanosheets block the C-S-H channel, and the water molecules form hydrogen bonds with the nitrogen and oxygen-containing groups in the gC3N5 grafted with oxygen- containing functional groups (g-C3N5-COOH), significantly inhibiting the movement of water molecules. The oxygen-containing functional groups on g-C3N5-COOH form hydrogen bonds with the non- bridging oxygen on the surface of C-S-H and the oxygen in EP, respectively. This enhances the interaction of the C-S-H/epoxy interface and reduces the degree of interfacial peeling. The impermeability mechanism of the C-SH/epoxy interface and the capture of corrosive particles can offer molecular insights into the interface design of cement/organic coatings.

Return to Publications page