An innovative method for measuring pavement dielectric constant using the extended CMP method with two air-coupled GPR systems

Ground penetrating radar (GPR) is a common non-destructive tool for pavement layer thickness measurement. The accuracy of such measurement is directly affected by the accurate prediction of the dielectric constant of pavement material using GPR. In this study, an innovative extended common mid-point (XCMP) method using two air-coupled GPR systems was developed to improve the accuracy of the traditional method for pavement material dielectric constant estimation. The equations and algorithm for calculating the dielectric constant of pavement material were developed, and then the accuracy of this new method was validated successfully by the data collected from a custom-designed test site. •An innovative method, XCMP, was developed to estimate pavement dielectric constant.•XCMP utilizes two air-coupled GPR antenna systems sharing the same mid-point.•XCMP works better for multi-lift thick pavements compared with the classic method.•The accuracy of XCMP can be further improved with increased GPR sampling rate.•XCMP is also applicable to many other structures in addition to pavement.