Study On Infrared Thermal Image Technique In Quality Inspection Of Anti-Crack Layer In External Thermal Insulation System On Wall

In this thesis, the feasibility of utilizing infrared thermal images apparatus for inspecting the quality of bond between anti-crack layers and insulation layer in external thermal insulation system on wall made of mortar with small expended and vitrified ball is investigated and discussed, based on the experimental study. Taking into account various exposure surroundings of buildings, the wall facing direction, moisture content, size and shape of defects layers are set as the testing parameters in this study. In order to inspect the quality of bond between anti-crack layers and insulation layer, samples with various defects are made in advance, and the thermal images obtained by the apparatus are analyzed and compared with the actual defects. The conclusion as follows can be drawn based on the testing results in this thesis:1. It is essential that accurate grasp of radiation rate of materials to determination of surface temperatures of the samples. As of temperature changes predominate inspection of defects, there is no significant influence of the radiation rate on experimental results of characteristics of defects. The radiation rate of anti-crack layer is0.86in this study.2. When defects are set in the exterior wall faced to east, south and west, their characteristics can be completely judged based on the obtained thermal images, but approximate locations of defects can be only estimated for the exterior wall faced to north.3. With moisture contents increase, thermal conductivity of insulated materials increases, and differences in temperatures increase between the surfaces of defects and its surroundings, more obvious display of the defects can be shown, which benefits effectiveness of inspection.4. Infrared thermal image apparatus can be used to inspect defects in anti-crack layer with various sizes and shapes. The larger size and depth of the defects are the better effectiveness of inspection is. In the range of this study, infrared thermal image apparatus can be used for inspecting defects with the sizes not smaller than20mm and the depths not smaller than3mm, which meets the need of inspection quality in construction engineering. 5. The shapes of defects can be shown much clearer and more stable in the thermal images for cooling phase (i.e., temperature drop) than that for heating phase (i.e., temperature rise).6. Infrared thermal image apparatus is suitable for quality inspection of anti-crack layer in external thermal insulation system on wall made of mortar with small expended and vitrified ball. However, for insulation system made of expanded polystyrene board, the method is only applicable to larger defects.