Advanced GPR Technologies for Mixed Pavement Type Evaluation: A New Jersey Case Study

Abstract: Accurate and detailed pavement layer identification and thickness measurement present significant challenges in New Jersey's complex roadway network, characterized by undocumented transitions between composite and flexible pavements. Historical as-built records often prove unreliable for determining complex pavement structure within the project boundaries. This study implemented two types of multichannel Ground Penetrating Radar (GPR) technologies: 3D Step-Frequency air-launched GPR and dual-frequency ground-coupled GPR systems. These systems were used to accurately identify layer interfaces and measure thicknesses in these mixed pavement types, extending to subgrade depths and unbound layers. While air-launched 3D GPR data was found to be compromised in areas with underground utilities and nearby electrical transmission lines, the complementary use of ground-coupled GPR provided additional validation and ensured comprehensive subsurface imaging. Field validations across multiple sites in New Jersey confirmed the reliability of this integrated approach in detecting subtle structural variations and layer interfaces. Results showed that this combination of GPR technologies provides transportation agencies with comprehensive structural data for informed maintenance planning and rehabilitation decisions, while reducing the need for exploratory coring. The accurate identification of pavement structure transitions enables agencies to sectionalize pavements more effectively, leading to optimized project scoping and more targeted rehabilitation strategies for long-term pavement performance.