Behavior of Carbon Fiber Anchors in Alkaline Environment

The durability of externally bonded carbon fiber reinforced polymer (CFRP) systems remains a significant challenge, prompting extensive global research to enhance their longevity. This study investigates the impact of accelerated conditioning on the flexural performance of concrete prisms reinforced with anchored CFRP systems. The strengthened prisms were immersed in water at 23°C with an alkaline pH of 11.4 for 6 and 18 weeks to simulate harsh environmental exposure. Four-point bending tests were conducted post-conditioning to evaluate load-bearing behavior, ultimate capacity, and capacity loss compared to control specimens. Results showed that short-term exposure (6 weeks) led to a 16% reduction in ultimate load capacity, attributed to early-stage degradation caused by alkali attack on the adhesive bond. Conversely, long-term exposure (18 weeks) resulted in a 6.25% increase in load capacity, reflecting the resilience developed through prolonged hydration, matrix densification, and stabilization of the FRP-concrete interface. These findings highlight the dual effects of alkalinity: initial degradation followed by long-term performance enhancement. This study underscores the importance of exposure duration and highlights the potential for improved durability in CFRP-anchored systems through optimized conditioning and material design.