Pavement Layer Dielectric Characteristics Of The Pilot Study

As a new non-destructive, speedy and lower-cost technology for pavement testing, the Ground Penetrating Radar (GPR) has played an important and indispensable role in testing of pavement properties, and shows a bright prospect and great benefit to society and economy.The dielectric difference of pavement material is the precondition of the application of GPR. The reflected GPR wave is the function of the material dielectric properties, and the explanation, estimation and backcalculation of GPR data are all based on the analysis of the material dielectric properties. The pavement properties, such as thickness, compaction, void content, moisture content and asphalt content etc, are all obtained based on the study of pavement dielectric property. Meanwhile, as a kind of composite material, the establishment of its dielectric model is an important step for studying the pavement dielectric property. Therefore, the study on the pavement dielectric and the dielectric model is an important part of the applied technology of GPR, and will supply a theory for the application of GPR.The experiment study on the pavement dielectric property and the dielectric model is done in this paper in order to solve the problems of GPR applied technology. The main achievements and conclusions of this paper are summarized as follows:1) The status and development of GPR applied technology, working principle of GPR, the characteristics of the pulse electromagnetic wave propagation in pavement systems and the application of the GPR in pavement testing and evaluation are introduced.2) The basic theory of dielectric property and the dielectric property of pavement material are analyzed to provide the theory for the application of GPR in pavement.3) The dielectric constant of the composite and volumetric concentrations and density of its components are gained through experiments on the dielectric properties of pavement material. Also the rules of dielectric constant's diversification in the age, the relationship between the dielectric constant and density, the relationship between the dielectric constant and strength and the influence of the asphalt-aggregate ratio, aggregate gradation and water cement ratio on the dielectric constant are obtained in this paper.4) Kinds of dielectric models and their applications are introduced. The flexibility of dielectric models of composite material normally used in pavement is validated and modified based on experiment.