Dielectric properties of asphalt pavement materials based on the temperature field

Nondestructive testing equipment evaluates the quality of asphalt pavements and identifies different distresses based on the difference in the relative permittivity of asphalt pavement materials at different positions of the asphalt pavement structural layers. Thus, the accurate determination of the relative permittivity of asphalt pavement materials is essential for the quality evaluation of asphalt pavements. However, the dynamic temperature field inside the asphalt pavement will affect the performance and dielectric properties of each layer mixture and therefore affect the detection accuracy of nondestructive testing equipment. In order to analyze the influence of the temperature field on dielectric properties of asphalt pavement materials, the relative permittivity of each structural layer of the actual core specimen was measured at different temperatures by using the Dielectric Constant Test Platform, and a temperature-based dielectric composite model was developed. Meantime, the temperature field simulation of the typical asphalt pavement structures and distresses were carried out based on COMSOL finite element simulation, and the heat radiation, heat conduction, and heat convection were theoretically analyzed. On this basis, the relative permittivity and the relative permittivity correction rate of each structural layer was calculated to quantify the influence of the temperature field on the dielectric properties of asphalt pavement materials. This study confirmed that a crucial correlation exists between the temperature and relative permittivity of asphalt pavement mixtures. The temperature field distribution of distresses, namely, top-down cracks, reflective cracks, and road cavity, were simulated, and then the measured dielectric permittivity of each asphalt pavement structural layer was corrected. These findings can provide a theoretical basis for the temperature correction of detection data of nondestructive testing equipment and lay the foundation for the accurate identification of typical distresses in asphalt pavement.