Defect size measurement and far distance infrared detection in CFRP-concrete and CFRP-steel systems

Knowledge of the precise size of unbond, debond areas and delaminations aids the assessment and evaluation of the integrity of structures retrofitted with carbon fibre-reinforced polymer (CFRP) systems. This assessment and monitoring can lead to reduced stress from over loading and keep the structure well beyond the serviceability limit. At the same time, reading the size of defects accurately can help radically with repair and maintenance. This paper investigates the ability of infrared thermography (IRT) non-destructive testing to determine subsurface defect sizes with high accuracy. Different designed defects in several specimens were measured using active pulse thermography technique IRT. These defects were located under different CFRP materials. Far distance detection and measurement of bond defects were also investigated with different pulse intervals applied to different specimens.