Synergistic Molecular Barrier and Hybrid Network Modifications for Enhanced Durability of Glass Fiber Reinforced Polymer Composites in Concrete

ABSTRACT Glass fiber reinforced polymer (GFRP) composites find extensive application in the field of concrete structures, but their long‐term performance is critically limited by the degradation of the polymer matrix under alkaline concrete environments. This paper presents a twofold modification strategy of using molecular barriers and stable crosslinking structure in the resin to improve its hydrophobicity, alkali hydrolysis, and interfacial bonding, and thus increase the durability of the GFRP composites. Results show that the synergistically modified system exhibits a 98.84% increase in hydrophobicity (contact angle: 140.58°) and an 80.70% reduction in surface roughness after alkali exposure, compared with the unmodified resin. After being subjected to prolonged alkaline aging, the modified resin shows a 61.21% increase in tensile strength retention, while the associated GFRP bars exhibit a 19.68% improvement in their strength retention. In addition, the synergistic effect of the three‐dimensional hybrid structure significantly enhances the interfacial adhesion between the fiber and resin. The interfacial interaction energy between the modified resin and glass fiber increased to 16 kJ/mol, accompanied by a 135.29% increase in maximum debonding strain. Therefore, this work provides a chemically synergistic and functionally graded resin matrix, which enables GFRP composites to retain long‐term performance in highly alkaline and corrosive concrete environments.