Enhancing bond properties between epoxy resins and cementitious materials through entropy-driven hydrophobic interaction

Abstract

The application of epoxy resin in coatings and grouting with cementitious materials significantly enhances structural durability by providing reinforcement and facilitating long-term maintenance. However, interface degradation between epoxy resin and cementitious materials remains a major challenge, especially in aggressive conditions. Drawing on the entropy-driven thermodynamic adhesion mechanism, this study introduces a novel approach to enhance bond strength via hydrophobic surface modification of the substrate. The treatment resulted in a 34.7 % increase in flexural bond strength, with the contact angle of the substrate rising from 17.2° to 101.4°. The primary driving force behind enhanced adhesion is the hydrophobic interaction between the benzene rings in the epoxy resin and the low surface free energy of alkyl groups on the cement surface. Furthermore, this improvement demonstrated long-term effectiveness under conditions of water immersion, thermo-oxidative aging, and ultraviolet exposure.