A critical review of infrared thermography as a method for non-destructive evaluation of FRP rehabilitated structures

The increasing use of fibre reinforced composites as externally bonded reinforcement on concrete as a means of rehabilitation has created a need for the development and implementation of rapid methods of field level non-destructive evaluation. These methods must provide inspectors with the ability not only to inspect structures for defects, but also to be amenable for use in varying field conditions and as a means of comparing size and location of defects between periods of inspection. Infrared thermography, which essentially uses data from temperature differentials to detect and characterise defects and anomalies, presents a potentially efficient technique for non-contact, real-time inspection and data interpretation. This paper provides a review of the technique itself, while assessing the variations thereof. It also provides a critical assessment of challenges that must be overcome before the method can be routinely used as a means of inspection of externally bonded fibre reinforced polymer (FRP) composites.