The use of fiber reinforced polymer (FRP) materials has been on the rise in bridge construction industry. They have been mostly utilized for strengthening purposes, especially as externally bonded reinforcement for columns, slabs, and beams. Their lightweight, flexibility and ease of installation, and higher strength offer an ideal solution for increasing the axial, bending, and shear resistance of existing concrete elements, as well as restoration and retrofitting of damaged members. FRP bars have also been used as internal reinforcement for concrete structural elements, providing corrosion-resistant alternatives to conventional steel reinforcements. Although the application of FRP for concrete members has offered many advantages, there have been issues and concerns associated with their long-term performance including their debonding from a concrete surface or within a concrete element. Accordingly, despite their durability, concrete elements strengthened/reinforced with FRP materials need to be inspected periodically to detect potential issues and hence prevent any premature failures. This study investigates Non-Destructive Testing (NDT) methods applicable to inspection of in-service FRP reinforced/strengthened concrete (FRP-RSC) bridge elements. Accordingly, this study first introduces damages and anomalies attributed to FRP reinforced/strengthened concrete bridge elements, and causes are discussed. The study includes a review of some promising NDT methods for the detection of these damages. The results of this study are expected to provide the inspection community more clarity in the application of NDT to FRP reinforced/strengthened concrete.
