Applications of Ground-Coupled GPR to Pavement Evaluation (7-2947-S)

Four case studies are presented in which ground-coupled ground-penetrating radar (GPR) was used successfully to identify subsurface problems in highway projects. These include identifying the extent of a subsurface aquifer so that a drainage system can be designed, locating underground storage tanks, locating potential sinkholes, and identifying the extent of damage caused by leaking water lines.Ground-coupled GPR has an advantage over air-launched systems in their depth of penetration. Low frequency units (100 MHZ) can penetrate 10-15 m (32-50 ft) in some soil types. The limitations of these systems are that the data collection speed is relatively slow 5-10 kph (3-6 mph), the data quality is severely impacted by the coupling between the antenna and the ground, and data interpretation relies heavily on expert interpretation. As with all GPR systems, the depth of penetration is severely limited in highly plastic clay soils.