Applications of Nondestructive Evaluation Techniques in Concrete Inspection

Ground penetrating radar (GPR) and infrared thermography (IRT), as two nondestructive evaluation-civil engineering (NDE-CE) technologies, are introduced in this paper to facilitate building inspection under the Mandatory Building Inspection Scheme (MBIS), as well as public housing blocks and government buildings in Hong Kong. Recognition of anomaly signal by GPR can be used for compliance check with design drawings by mapping embedded objects, and to distinguish variation of material properties such as wet or dry concrete. Post-image processing of IRT images by gradient computation provides an estimate of boundary and size of debond over external wall envelop of high-rise buildings. Both techniques are promising in MBIS because these techniques see through the ‘unseen’, and are completely nondestructive, rapid, relatively low-cost and offer data in very high resolution.