Three-Dimensional Orthorectified Simulation and Ground Penetrating Radar Detection of Interlayer Bonding Condition in Asphalt Pavements

To assess three-dimensional ground-penetrating radar (GPR) applicability for evaluating interlayer bonding in asphalt pavements with semi-rigid base layers, and analysis the GPR detection mechanism. Using forward simulation to create various medium models and analyze electromagnetic wave transmission in air, water, and sand. Four distinct pavement structures were subjected to GPR testing, and the amplitude intensity levels and image processing techniques to assess asphalt pavement interlayer bonding, and validated by comparing the results with core samples. The findings revealed that electromagnetic wave transmission processes were significantly influenced by medium uniformity. Non-uniform medium models generated considerable stray waves, akin to typical "noise," closely mirroring real pavement conditions. Poorly bonded areas exhibited clearer hyperbolic ripples, primarily due to significant differences in dielectric constants of filling materials. Amplitude strength effectively evaluated bonding across different asphalt pavement configurations and lanes, typically following a normal distribution. Enhanced interlayer contact correlated with smaller amplitudes, while weaker bonding led to larger amplitudes. The amplitude distribution in the center of lanes differed significantly from wheel track areas, and the interlayer bonding condition of center lanes was better than wheel track belt. Additionally, radar plan views exhibited considerable variation across different interlayer contact conditions. The image processing method can evaluate the interlayer contact condition of different pavement structures across full cross-sections.