Dielectric constant influences and mechanical correlations in asphalt mixtures: Implications for non-destructive testing

Ground penetrating radar (GPR) offers a rapid and non-destructive approach to evaluating asphalt mixtures by capturing variations in their dielectric constant. As a critical electromagnetic parameter, the dielectric constant demonstrates significant potential for assessing the material composition and mechanical properties of asphalt mixtures. However, the relationship between the dielectric constant and mechanical properties remains unclear. To investigate the factors affecting the dielectric constant and its correlation with the mechanical properties of asphalt mixtures, a systematic analysis of the influencing parameters was conducted. Fitting equations were established to quantify the relationships between the dielectric constant and mechanical properties. Firstly, the effects of compaction state, testing frequency, and testing temperature on the dielectric constant were evaluated. Subsequently, forward simulations of GPR were executed on asphalt pavements with diverse air voids and detection frequencies. Finally, a fitting analysis was performed to determine the correlation between the dielectric constant and the dynamic modulus, compressive strength, and splitting tensile strength. The results indicated that the dielectric constant increased with the compaction state, decreased with increasing testing frequency until stabilized, and was insignificantly affected by changes in testing temperature. The change of air void in asphalt pavement has significantly affected the amplitude and timing of electromagnetic wave reflection. A linear positive correlation was identified between the dielectric constant and dynamic modulus as well as compressive strength, while a quadratic positive correlation existed with splitting tensile strength. This study provided theoretical and practical foundations for enhancing the reliability and accuracy of non-destructive testing in asphalt pavement. • Effects of compaction state, testing frequency, and testing temperature on the dielectric constant were evaluated. • Forward modelings of ground penetrating radar were conducted on asphalt pavements under various conditions. • Fitting equations relating the mechanical properties and dielectric constant of asphalt mixtures were established.