Deterioration mechanism of adhesion properties of FRP-soil interface induced by moisture

PC Wei and ZY Yin and YJ Wang and FP Gao, CANADIAN GEOTECHNICAL JOURNAL, 62, 0317 (2025).

DOI: 10.1139/cgj-2025-0317

The deterioration of fiber-reinforced polymer (FRP)-soil interfacial adhesion due to water intrusion has been a core issue in geotechnical engineering, but its microscopic mechanism remains unclear. In this study, molecular dynamics (MD) simulation method is employed to reveal the microscopic deterioration mechanism of water on adhesion properties of epoxy-quartz (i.e., FRP-soil subsystem) interface, the structural and dynamic characteristics of interlayer water film. The steered molecular dynamics pulling simulation and the modified Bell's model are used to evaluate the adhesion energy of epoxy-quartz interface in dry and wet cases. The simulation results show that (1) the interfacial water film weakens adhesion strength of epoxy-quartz interface, playing a dual role in "interface isolation" and "lubrication", aggravating the interfacial debonding. (2) The work of adhesion, maximum pulling force, potential of mean force, and adhesion energy of dry system are significantly higher than those of wet system. (3) The interlayer water film has a distinct layered structure: bound, free, and sparse water layers, which have different angle orientations and density distributions. (4) The diffusion coefficient increases with the rising thickness of free water layer, which may trigger a capillary-seepage effect and aggravate interface deterioration. This study provides atomic-scale insights into moisture-induced FRP-soil interface failure mechanism.

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