Evaluation of heat transfer properties of asphalt mixtures
Seong-Kyum Kim, Kwan-Ho Lee
Abstract
The purpose of this study is to evaluate the heat transfer characteristics of three representative types (WC-2, reWC-2, PA-13) of asphalt pavement used in Korea and provide basic properties for future related research. Thermal conductivity, specific heat capacity, thermal emissivity and diffusivity were conducted under various conditions according to ASTM and KS. The WC-2 displayed a 12.6 % higher maximum heat flux compared to the PA-13. Furthermore, when comparing thermal conductivity obtained via HFM, the thermal conductivity was 51.5 % higher for the WC-2 and 27.8 % higher for the PA-13. In the case of the WC-2 with low porosity, there is a greater potential for heat accumulation and faster heat transfer than in the PA-13. The change in heat flux of saturated asphalt mixtures due to heat accumulation occurred in two stages, dependent on upper surface and lower evaporation. Moisture within the pores of a specimen, as opposed to complete dryness, led to increased thermal conductivity. Water occupied the volume that air typically occupied, which reduced the temperature difference between the upper and lower portions. As a result, thermal conductivity values increased by up to 4.4 % for the WC-2 and up to 21.7 % for the PA-13.