Incorporating transmitter–receiver offset to interpret pavement layer thicknesses by GPR

This study evaluates the necessity of considering Transmitter–Receiver (T–R) offset distance for predicting pavement layer thicknesses from two-way travel time data captured by a Ground Penetrating Radar (GPR) antenna. For the purpose of this study, GPR testing was conducted at an instrumented pavement section at Milepost (MP) 141 on Interstate I-40 near Albuquerque, New Mexico, USA. The GPR system used for this study consists of 2.0 GHz air-launched, 900 MHz ground-coupled, and 400 MHz ground-coupled antennas. The entire instrumented test section was tested with different antenna configurations. The two-way travel time is used for calculating layer thicknesses using two approaches: one considering the T–R offset, which is a non-conventional approach and the other without considering the T–R offset, which is a conventional approach. Statistical analysis namely, t-test is performed on the predicted layer thicknesses from these two approaches. The analysis indicates that these two approaches are significantly different. The predicted thicknesses by these two approaches are compared to each other. It is observed that the approach considering the T–R offset predicts the layer thicknesses with better accuracy compared to the conventional approach. Therefore, it is recommended to use the T–R offset in predicting pavement layer thickness from GPR data.