Continuous real-time monitoring of flexible pavement layer density and thickness using ground penetrating radar

Static or discrete time prediction of flexible pavement asphalt concrete (AC) layer density and thickness utilizing the ground penetrating radar (GPR) has proved to be relatively accurate compared to other in-situ methods. However, the accuracy during continuous monitoring of construction has not been validated by real construction projects. This study investigated the continuous estimation of AC layer density and thickness using GPR at a construction site in Macomb, Illinois. The first test compared AC layer density and thickness for pavement segments built in two consecutive days. The second test evaluated the construction quality of pavement segments built utilizing two types of material transfer vehicles (MTV). The GPRan software and the proposed truncation algorithm were used to calculate AC layer thickness continuously. The AC layer density and thickness estimation results were compared to core data using the ALL model. The GPR estimation values were found to be reliable. Errors of thickness results between continuous GPR data and core data from two tests are approximate 3% and 6%, respectively. The density of the new pavement segments was larger than the old ones while the thickness was almost the same. The average error between continuous density predictions and core density was 3%. The two MTVs performed similarly based on layer thickness and density results.