Evaluation of Road Pavement and Subsurface Defects Mapping Using Ground Penetrating Radar (GPR)


GPR is frequently used for inspection road pavement (thickness estimation, damage detection and diagnosis), so this technique was selected for this purpose. Three types of antennas were used: 250, 500 and 800 MHz. In the field, the survey has been carried out on one lanes paved road about 1250 m long inside University of Technology Campus. The obtained radargrams raw data were analyzed using sophisticated softwares to determine asphalt and concrete layers thicknesses for base and subase. Several inspections have been carried out to study the effect of changing the operating setting parameters of GPR on the data accuracy and interpretation for paved roads damages and the pavement layers thicknesses. The interpretation results, using 250 MHz antenna, showed the possibility of identifying buried plastic pipe and the flexible pavement layer. While the rigid pavement layer is unresolved. With 500 MHz antenna, the plastic pipe, rigid pavement, steel reinforcement bars and joint sheet cork appeared clearly. It was found that the short type of the Max. Time Window using antenna 800 MHz is the most suitable for detecting some radar anomalies (plastic pipe, cork sheet and reinforcement bars and pavement thickness) which were more clearly defined. No change is noticed on radargrams when applying different point intervals. The suitable radar wave velocity for estimating the thicknesses of the surface, binder and rigid pavement layers were 80, 160 and 180 m/ns respectively. While, the surface cracks were undetectable with 800 MHz antenna but the cause of such crack was identified. Correlation GPR thickness data with the asphalt core data, states that the error of the thickness measurements from GPR resulted in average deviation (the percentage error) of about 4%.