Durability of Reinforced Concrete Beams Externally Strengthened with CFRP Laminates under Harsh Climatic Conditions

This paper addresses the durability of reinforced concrete beams strengthened with carbon fiber-reinforced polymer (CFRP) laminates under natural and saline environments in the Arabian Gulf. Beam specimens were conditioned under sunlight and saline water for 180, 360, and 730 days and tested under four-point bending until failure. The load-deflection curves, strains, failure modes, ductility, and stiffness of the exposed beams were evaluated. The CFRP-strengthened specimens exhibited a 67% higher ultimate load capacity than control specimens after 28 days and up to 51% and 71% higher load capacity than control specimens after two years of direct sunlight and saline water exposure, respectively. No pronounced loss in strength and stiffness or damage to the epoxy was observed. Failure modes were transformed from cohesive to adhesive due to saline water exposure, whereas sunlight-exposed samples exhibited no failure-pattern change, and failures remained cohesive or interfacial. For design and analysis, environmental strength reduction factors are proposed and compared to current industry guidelines. Thus, CFRP-strengthened laminates can endure and perform effectively when subjected to severe environments of high salinity, temperature, and humidity.