Cooling optimization of asphalt pavement by topology optimization and cooling mechanism analysis

Abstract

The higher temperature in the hot summer area will seriously damage the safety and comprehensive performance of the asphalt pavement, thus it must be cooled down quickly and orderly. At present, the cooling pavements are designed mainly based on engineering experience, and the quantitative relationship between design objective and variable is not constructed during the design process. In addition, it is difficult to determine whether the material distribution of cooling pavement is optimal. These limit the further improvement of the pavement cooling effect. In this study, the relationship between the design objective (minimum average temperature of upper layer) and design variable (thermal conductivity of pavement) of cooling pavement was built by numerical simulation, and the cooling pavement with the best cooling effect was obtained by topological optimization technology. The influence of the initial value and distribution of the thermal conductivity on the average temperature were explored during the design process. The thermal effect analysis and thermal resistance were used to determine cooling mechanism of optimized cooling pavement. The topology optimization results demonstrated that the minimum average temperature could be obtained when the initial value of the thermal conductivity gradually increased with the increase in pavement depth. The optimized cooling pavement showed good cooling effect at night. The thermal effect analysis results showed that the design of optimized cooling pavement reduced the net heat absorption and the heat transfer efficiency of the pavement, and increased the thermal resistance inside the pavement, thus achieving the pavement cooling. Compared with the ordinary asphalt pavement, the pavement surface temperature and interior temperature could be reduced by up to 9.18 °C and 13.29 °C, respectively. The maximum heat absorption, dissipation and net heat flux absorption of the optimized cooling pavement were decreased by 65.59 %, 63.87 % and 59.40 %, respectively. The reduction of the net heat flux absorption and heat release in the optimized cooling pavement are conducive to mitigating the high temperature rutting and the heat island effect at night, respectively. Finally, the indoor irradiation test was carried out to evaluate the cooling effect of optimized model. The temperatures of optimized group at 7 cm and surface were 5.29 °C and 2.5 °C lower than those of control group, respectively. The effectiveness of the topology optimization design for cooling pavement were verified.