IR thermography for interface analysis of FRP laminates externally bonded to RC beams

Non-destructive (ND) evaluation by thermographic analysis was applied to reinforced concrete (RC) beams strengthened with CFRP lam- inates, to assess the quality of the interface between reinforcement and substrate before and under load- ing, during laboratory bending tests. The proper algorithm for processing data acquired from the thermographic system was first selected by testing reduced-scale fiber reinforced polymer (FRP)- strengthened concrete slabs with artificial defects and anomalies, deliberately placed at the interface. Portable heating equipment was purposely set-up to allow continuous scanning along the loaded beams. Results showed that infrared thermography (IRT) can supply significant qualitative and quantitative infor- mation on bonding of FRP materials applied to structural substrates, for both preliminary and in-situ investigations, by means of a reliable low-time- consuming procedure. Cross-evaluation of crack patterns during bending tests and thermographic results are also presented.