Active infrared thermographic inspection technique for elevated concrete structures using remote heating system

Conventionally, the inspection of elevated concrete structures requires the use of scaffolding or an aerial truck. In this study, elevated railway structures constructed of reinforced concrete were inspected using active infrared thermography. The inspection area corresponded to half of the middle slab covering an area of 16.8 m2; one inspection was carried out that took about 15 min. A remote heating system consisting of a 6-kW air-cooled xenon arc lamp and a scanner system was developed to detect hidden defects in elevated concrete structures without the need for an aerial truck or scaffolding. The generation of a thermal image and irradiation are carried out simultaneously by the beam scanning. High-contrast infrared thermal images can be obtained by the simple image processing procedure that is proposed.