NDE of fiber-reinforced polymer composites bonded to concrete using IR thermography

Infrared thermography is a non-destructive evaluation technique that can be used to identify debonded areas in FRP strengthening systems applied to concrete. This research provides a summary of IR thermography experiments that were conducted on full-scale AASHTO girders strengthened with four different FRP composite systems. Significant findings were that the thickness of the FRP system as well as the material composition strongly influences the ability to detect defects at the FRP/concrete interface. Additional experiments were conducted on small-scale specimens with implanted defects. Results from these experiments indicate that IR thermography is capable of detecting defects under multi-layer FRP composite systems; however the defect signal strength and time to maximum signal vary significantly from single-layer systems.