Cooling asphalt pavement by a highly oriented heat conduction structure

• The designed structure absorbed less 9.3% solar radiation heat.
• The structure can induce inner accumulated heat to subgrade.
• The structure releases less 12.1% heat into the atmosphere during nighttime.

In this paper, a highly oriented heat conduction structure of asphalt pavement, with a combination of low thermal conductivity layer and three-layered gradient heat conduction structure, was proposed to reduce pavement temperature and decrease nighttime heat release into the atmosphere in summer. The structure was formed by modifying contrast asphalt pavement by adding different dosages of low thermal conductivity powders to each layer. Also, it made full use of principles of thermal insulation and gradient heat conduction, and extended the scope of thermal gradient in asphalt layers. The results showed that, compared with contrast structure, the highest temperature of upper surface of bottom layer, which was used to represent the average temperature of middle and bottom layers, reduced by 2.3 °C (simulation result) and 2.4 °C (test road result). The average temperatures of middle and bottom layers reduced by 1.6 °C (at 2:30 pm) and 1.5 °C (at 6:00 pm), respectively, which were validated by test road results. Calculations of simulation result displayed that the structure released less 12.1% of heat to the atmosphere during nighttime than contrast structure. According to the results summarized above, it is concluded that the structure has a continuous cooling capacity, and is expected to reduce high temperature rutting of asphalt pavement and help to reduce high air temperature at night.