Defect detection of concrete structures using both infrared thermography and elastic waves

There are many nondestructive testing techniques that can be applied to assess the condition of existing concrete structures with little expenditure of human labor. The objective of the current research is to pilot-study how one can combine active infrared thermography (IRT) with elastic wave techniques. In such a manner, the fast scanning of a large structure is followed by elastic wave probing at a given small area. Concrete slabs with embedded defects are heated by means of lamps prior to acquisition of thermal images. The thermal images recorded show clear indication of hidden defects of various depths and areas. At present, the results of IRT provide only limited quantitative information regarding the depth of hidden defects in concrete. Depth of defects is readily deduced based on spectral analyses of received elastic wave signals. The fusion of information gathered from IRT and elastic waves provides effective and efficient means for inspection of the building exterior.