Influence of Temperature on the Dielectric Properties of Asphalt Mixtures

Asphalt mixtures, composed of air, aggregate (limestone), and asphalt (matrix), are sensitive to temperature. In order to clarify the influence of temperature on the dielectric properties of asphalt mixtures and improve the accuracy of ground-penetrating radar (GPR) testing, this paper investigates the dielectric properties of limestone, two types of asphalt [Asphalt 70 and styrene-butadiene-styrene (SBS)-modified asphalt] and asphalt mixtures [stone matrix asphalt (SMA) and SBS-SMA mixtures] covering temperature range of -30 degrees C to 60 degrees C using the open-ended coaxial probe kit method and waveguide cavity method, respectively. The results indicate that the dielectric constants and loss factors of limestone, asphalt, and asphalt mixtures increase in various degrees with the increase of temperature. Approximately linear relationships between the dielectric constants and loss factors of limestone, asphalt, and asphalt mixtures and temperature are discerned. This denotes the influence of temperature on the dielectric properties of asphalt mixtures is not negligible. At the same time, the accuracy of nondestructive testing and evaluation of asphalt pavement based on GPR technology highly depends on the composite dielectric model of asphalt mixtures. Via the introduction of temperature coefficients, the dielectric regression model of asphalt mixtures considering the effect of temperature is established. Compared with the traditional dielectric models, the proposed model has higher accuracy. (C) 2022 American Society of Civil Engineers.