Research on dielectric properties of asphalt concrete with GPR

While the thickness of asphalt road surface was detected with Ground penetrating radar, Velocity of GPR wave was a key to calculate thickness well and truly. In order to get a new method to calculate speed, three groups of asphalt concrete samples were made in laboratory, which component and thickness were different. Then their dielectric constants were measured using reflection wave method. Based on these measured data, the dielectric constant model of asphalt concrete and external factors was analyzed. Studies results show that the dielectric constant of asphalt mainly depends on its composition ratio and dielectric properties; it may be indicated by an amended linear model. In addition, the thickness of test block and changes of antenna frequency also affect the dielectric constant value we should correct it during the test. Case study showed that calculating thickness with the new formula could greatly improve the accuracy of detected pavement thickness.