Abstract
Conductive asphalt concrete with high thermal conductivity has been proposed to improve the solar energy collection and snow melting efficiencies of asphalt solar collector (ASC). This paper aims to provide some insight into choosing the basic materials for preparation of conductive asphalt concrete, as well as determining the evolution of thermal characteristics affected by environmental factors. The thermal properties of conductive asphalt concrete were studied by the Thermal Constants Analyzer. Experimental results showed that aggregate and conductive filler have a significant effect on the thermal properties of asphalt concrete, while the effect of asphalt binder was not evident due to its low proportion. Utilization of mineral aggregate and conductive filler with higher thermal conductivity is an efficient method to prepare conductive asphalt concrete. Moreover, change in thermal properties of asphalt concrete under different temperature and moisture conditions should be taken into account to determine the actual thermal properties of asphalt concrete. There was no noticeable difference in thermal properties of asphalt concrete before and after aging. Furthermore, freezing–thawing cycles strongly affect the thermal properties of conductive asphalt concrete, due to volume expansion and bonding degradation.
Highlights
Asphalt binder is a viscoelastic solid at ambient temperature, which acts as a glue to bind aggregates and mineral fillers together [1]
Various 2-D/3-D steady/transient models have been developed to study the thermal response of asphalt pavement by the finite element method (FEM) [2,5,6,7] and the finite difference method (FDM) [8,9]
The main objective of this paper is to provide some insight into choosing the basic materials commonly used in pavement for design and preparation of conductive asphalt concrete, as well as determining the evolution of thermal characteristics affected by environmental factors for accurately assessing the performance of asphalt solar collector (ASC)
Summary
Asphalt binder is a viscoelastic solid at ambient temperature, which acts as a glue to bind aggregates and mineral fillers together [1]. Since asphalt molecules consist of weak chemical bonds that could be changed with temperature, mechanical behavior of asphalt pavement is strongly dependent on temperature. Such flexible pavement would be relatively “soft” and susceptible to permanent deformation under repeated traffic loading at high temperature, while it would be relatively “hard” and susceptible to thermal cracking at low temperature [2,3]. An understanding of temperature distribution is highly essential to determine the physical properties of asphalt mixture for predicting the pavement performance (e.g., rutting resistance analysis or thermal cracking analysis) [4]. The thermal properties of asphalt mixture—such as the thermal conductivity, thermal diffusivity, and specific heat—have significant effects on the distribution and variation of Materials 2017, 10, 218; doi:10.3390/ma10030218 www.mdpi.com/journal/materials
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