Infrared thermography and ultrasound techniques for detecting FRP-concrete adhesion problems

Externally bonded Fiber Reinforced (FRP) are increasingly being used for strengthening, repairing and retrofitting of existing structures due to their excellent mechanical and physical properties. However, the structural efficiency of the reinforcement techniques is dependent on a proper application. For this reason an important role is played by the quality control of the application by using Non Destructive Techniques (NDT). In this paper, Infrared Thermography (IRT) and Ultrasound Techniques (UT) have been experimented for non destructively evaluating concrete specimens strengthened with different kind of FRP, with the aim of verifying the reliability of IRT and UT in detecting adhesion anomalies and defects. For this purpose, some ar-tificial defects of various sizes and depth were deliberately settled in the interface between the FRP and its substrate on the specimen