Durability of FRP bars and FRP-reinforced concrete beams: A critical review of accelerated aging tests and performance insights

The utilization of fiber-reinforced polymer (FRP) bars in concrete structures offers a promising solution to tackle the chloride-induced corrosion issues of steel reinforcement in concrete. Against this background, extensive research has been conducted on the durability of FRP bars at both material and component levels, aiming to promote the application of this high-performance structural material. This paper presents a comprehensive review on the accelerated aging tests (AAT) related to FRP bars, FRP bar-concrete bonded joints and FRP-reinforced concrete beams subjected to various environmental conditions (e.g., solution immersion, wet-dry cycles, freeze-thaw cycles, high temperature, UV radiation) and/or loading conditions (i.e., with and without sustained loads). Critical parameters influencing the durability issues are extensively discussed based on three databases that were collected by the authors containing over 15,200 test specimens. The findings indicated that the mechanical properties of FRP bars were particularly sensitive to direct solution immersion. A significant dispersion in the test results for bond strength, closely related to bar surface treatment, was observed compared to other mechanical properties of FRP bars. The coupled actions of environmental conditioning and sustained loading were found to have a significantly detrimental impact on the tensile strength of FRP bars, while sustained load tended to reduce the load capacity and overall behavior of FRP-reinforced concrete beams, regardless of exposure conditions. Based on the findings from the review, recommendations for future work are also proposed.