Computational analysis of thermal conductivity of asphalt mixture based on a multiscale mathematical model

This paper presents an analytical method to determine the effective thermal conductivity of asphalt mixture, considering morphological characteristics and thermal properties of each component. The heat transfer process in asphalt mixture was modeled through reasonable simplifications. A multiscale model was developed to calculate the effective thermal conductivity of asphalt mixture based on the principle of minimum thermal resistance. The thermal prediction results were validated with experimental data reported in the literature. A new parameter, regarded as the morphological factor, was deduced to quantify the contribution of dispersed phase morphology to thermal conductivity of asphalt mixtures. The results show that the morphological factor of coarse aggregate, generally ranging from 0.2 to 0.7, can be represented by normal distribution. The sphericity and orientation angle of coarse aggregate have combined effects on the effective thermal conductivity of asphalt mixture, which can be characterized by the proposed morphological factor. Moreover, the effective thermal conductivity is positively related to aggregate content, thermal conductivity of aggregate, and fine aggregate matrix, but negatively correlated with morphological factor and porosity.