Delamination characterization in thin asphalt pavement structure using dispersive GPR data

Detection of delamination in asphalt pavement by non-destructive ground penetrating radar (GPR) is useful for effective maintenance and repair. However, limitations of GPR survey resolution and multiple wave interferences have made thin delamination layer characterization a challenging task in conventional common offset profiling (COP) mode. In this paper, a new method is proposed for characterizing delamination layers in asphalt pavement using the GPR waveguide dispersion model in a wide-angle reflection and refraction (WARR) configuration. The approach was validated through synthetic experiments and laboratory experiments using an asphalt pavement model. The results show that the cutoff frequencies of all modes are sensitive to air-filled delamination, while water-filled delamination leads to a significant decrease in the phase velocity of GPR waves. By observing these trends, we are able to detect delamination layers with 1 cm thickness and identify delamination layers with different properties. This new method can aid in the detection and identification of delamination layers in asphalt pavement structures.