Application of infrared thermography for debonding detection in asphalt pavements

Conventional testing practices in pavement damage surveillance and maintenance such as coring tend to be slow, destructive in nature and not wholly representative of the entire stretch of the pavement. Newly emerging technologies based on non-destructive testing techniques, do not demand implementing destructive measures or relying on extrapolation of point data and can be implemented after developing them into a proper technique and a set testing protocol. One such emerging technique that uses infrared emissions from any structure to inspect underlying defects is infrared thermography (IRT). In a patch of pavement containing subsurface defects, the heat flow to the surface of the pavement, which itself depends on the incident solar radiation, ambient temperature and other meteorological factors, gets disrupted causing a difference in the thermal signature of the defective and the sound patches. This difference in thermal signature can potentially be detected by a thermal imaging camera. This study aims at exploring the potential of IRT technique to assess the subsurface debonding defect in asphalt pavements. For this purpose, an in situ asphalt pavement test section has been constructed and different interlayer bonding conditions have been artificially induced in it. A novel way for quantitative and qualitative analyses of thermal signatures, using MATLAB for each of these bonding conditions has been carried out. The effect of different debonding agents on the overall thermal behavior of asphalt pavement has also been evaluated. Interchange time duration between day heating and night cooling cycles has been estimated, to determine the suitable time duration for asphalt pavement inspection. The results, advantages, and limitations of the method have been presented.