Developing Inspection and Damage Detection Methods for FRP Reinforced/Strengthened Concrete Elements

The use of fiber-reinforced polymer (FRP) rebars as reinforcement and FRP sheets for repair and strengthening concrete elements has been gaining momentum as an alternative to conventional steel. This is mostly due to its benefits including lighter weight, higher strength, and better durability. However, very limited research has been conducted in relation with non-destructive testing (NDT) methods for such elements, especially those that would be applicable to damage detection in FRP bars embedded in concrete. The ability to assess the condition of the relatively new and unique FRP reinforcements will increase the confidence of the construction industry in their use as a reliable substitute to steel reinforcements. Additionally, it will provide much needed information about condition of FRP reinforced/strengthened concrete (FRP-RSC) elements for assessment of current and future condition necessary for an effective life-cycle, risk-based risk, and reliability assessment. This research project first highlights the similarities and differentiating aspects between conventionally reinforced concrete and FRP-RSC elements. It then presents the information available to-date and innovative approaches to develop or adapt tools and methods of evaluation to fill the gaps in the knowhow. Lastly, it introduces promising NDT methods and investigates their ability for damage detection and condition assessment of FRP-RSC elements. The paper also recommends inspection and condition rating methods for such elements as per established inspection specifications. The results also emphasize the need for further research and developments related to NDT applications to embedded FRP rebars. By providing the inspection community with more clarity in the application of NDT to FRP, this study offers means for verifying the performance and, therefore, help the proliferation of FRP materials in concrete structures.