Infrared thermography detection of delamination in bottom of concrete bridge decks

Abstract

Infrared thermography (IRT) has been widely used in detecting the subsurface delamination of bridge deck. However, IRT inspection on delamination zones of the bridge deck which have limited exposure to direct solar radiation (e.g., the bottom surface of the bridge deck) is rather challenging due to the relatively low thermal contrast (ΔT) development in these zones. Therefore, the purpose of this study is to conduct a series of experimental studies in conjunction with numerical modeling for investigating the effectiveness of IRT in delamination detection of bridge deck components which are normally not exposed to direct solar radiation. Specially, the effects of different environmental conditions, thickness of bridge deck, and defect characteristics on the absolute thermal contrast (ΔT) development were systematically investigated. The results show that IRT can effectively detect the subsurface delamination of concrete bridge deck located in regions that are not exposed to the direct solar radiation. In addition, the development of detectable thermal contrast (>0.5 C) is much dependent on the rate of change in ambient temperature with a suitable detection period between 8 am and 4 pm. Furthermore, it shows that the value of ΔT increases with the increase of bridge deck thickness and delamination size.

Experimental evaluation of heat transition mechanism in concrete with subsurface defects using infrared thermography

“…These insulations on the side faces did not cause any disturbance to the flow of heat into the slabs from top surface, collecting the thermal images and analysing the heat transfer mechanism around the defective concrete. Similar concept of applying insulating formwork on the boundaries of test slabs to imitate larger concrete structures was also adopted by other researchers such as Nasim Khan Raja et al [37,38].…”