A Comparison of Dielectric Constants of Various Asphalts Calculated from Time Intervals and Amplitudes

When measurements by a Ground Penetrating Radar are evaluated, a dielectric constant is very important electrical property of pavement materials. The numerical value of the dielectric constant is different for various materials used in road construction and it affects the signal velocity in pavement layers. The main subject of research outputs introduced in the article is comparison of dielectric constants of the various asphalts calculated from time intervals and amplitudes. The series of laboratory and in situ measurements were made on three different asphalts (Asphalt Concrete (AC), Porous Asphalt (PA) and Stone Mastic Asphalt SMA)). The Ground Penetrating Radar (GPR) with 2 GHz air-coupled antenna was used. The antenna was moved over three sections: floor, a steel plate and an asphalt slab. The dielectric constant of asphalt was determined using time interval between positive amplitudes peaks representing the asphalt slab thickness and also using the amplitudes values. It was found the dielectric constants of the AC, PA and SMA differed regardless the calculation method. Differences in dielectric constant values were also found between two calculation methods.