During flaw evaluation of road bridge floor slabs, confirmation of the cracks in terms of width, angle and area is critical. With the thermography method, one of the available diagnosis techniques, it is difficult to evaluate the cracks developed by thermodiffusion by using the heat source from the measuring plane. In this study, correlations of the various crack patterns generated on RC girders and changes in the surface temperature were clarified using the heat transfer of the pavement heat supplied from the floor slab surface during asphalt improvement work, rather than the measurement plane. As a result, it was confirmed that various surface temperature distributions corresponding to crack patterns could be confirmed in heat images from the heat transfer of pavement heat, and that the pattern of developed cracks can be conjectured. Furthermore, in the non-steady heat transfer analysis, the evaluation method of cracks in terms of width, angle and area as well as the reproducibility was also were clarified.
