Pavement Evaluation Using Ground Penetrating Radar

Ground Penetration Radar (GPR) is fast becoming a viable technology for pavement survey. It is a noninvasive, continuous, high-speed field test tool that has been used for evaluation of pavement conditions. Potential applications of GPR include: (1) determination of pavement layer thickness; (2) striping layer of asphalt pavement; and, (3) subsurface defects and underground objects. Currently, the Office of Materials at Mn/DOT owns a SIR 2000 data acquisition system and 4 antennae. The GPR technology has been used in the state to help local and district engineers evaluate pavement conditions, such as pavement thickness and underground objects. The Minnesota Road Research (MnROAD) test facility has been used to verify the system and it shows that the calculated pavement thickness from GPR is within 5% of traditional field test coring result. Furthermore, a research project is being conducted to use GPR time history data to obtain dielectric constant and pavement thickness together. Software based on wave propagation is developed to analyze and determine the two parameters. The results showed that this method gives reasonable results on both dielectric constant and thickness. This is an improvement over the current GPR analysis, which requires an estimate on dielectric constant to obtain pavement thickness. The paper will describe Mn/DOT's experience on GPR applications and data analysis techniques.