Research on thermal properties and heat transfer of asphalt mixture based on 3D random reconstruction technique

Abstract

This paper presented a 3D random reconstruction technique (3DRRT) of asphalt mixture considering design parameters and aggregate shape features. Virtual sample of asphalt mixture was assumed to be composed of three components: coarse aggregate, asphalt matrix, and air voids. Then, 3D heat transfer finite element models were performed to predict thermal parameters of asphalt mixture. Besides, the computed results were compared with the direct experimental measurements given in the literature. Finally, effect of design parameters and material properties of each component on the thermal properties of asphalt mixture was investigated in the computational environment. The results indicate that it is reliable to predict the thermal properties of asphalt mixture based on the FEM with 3DRRT. The gradation type, aggregate particle shape and air voids size have little influence on the thermal conductivity of asphalt mixture. The thermal conductivity of asphalt mixture is affected by the interaction of each component. When the heat transfer capacity of asphalt matrix is lower than that of aggregate, the increase of asphalt content will reduce the thermal conductivity of asphalt mixture. However, a reverse trend will be observed when the thermal conductivity of asphalt matrix is higher than that of aggregate. The thermal conductivity of asphalt matrix has a decisive impact on that of asphalt mixture. Therefore, it is recommended to modify the thermal conductivity of asphalt matrix to enhance or weaken that of asphalt mixture. Simultaneously, the thermal conductivity of asphalt mixture decreases with the ascent in air voids content. As for heat transfer in asphalt mixture, coarse aggregate particles constitute the main channel of heat transfer, asphalt matrix acts as a bridge in the heat transportation, and the air void plays the role of thermal resistance.