Extremely high thermal conductive cement-based composites with diamond/ZnO/expanded graphite thermal conductivity network for cooling road

In recent years, the deterioration of traffic safety due to high road temperatures and the increase in transport costs have led to an urgent need for road users to reduce the temperature of the road surface. In this paper, high thermal conductivity diamond/ZnO/expanded graphite (D/ZnO/EG)1 cement-based composites were prepared by constructing and optimizing a thermal conductivity network in a cement matrix to achieve road cooling. Thermal network structure and porosity’s impact on thermal conductivity had both been investigated, and the mechanism governing thermal conductivity had also been analyzed. With a thermal conductivity of 6.338 W/(m·K), 732 % of the cement matrix, the result showed that the expanded graphite (EG) thermal conductivity network and D/ZnO significantly enhanced heat transfer. The excellent thermal transfer capacity of D/ZnO/EG cement-based composites was also shown to be beneficial in reducing pavement temperatures in the temperature distribution simulations at the road surface under solar irradiation. The above results illustrated the EG network thermal’s conductivity, the impact of D in shortening the EG spacing, and the impact of ZnO in filling the gaps, all of which were effective in enhancing thermal conductivity. In addition, D/ZnO/EG prevented crack extension and thus attenuated the damage to thermal conductivity caused by freeze–thaw cycles. This work confirms that the D/ZnO/EG cement-based composite can achieve effective heat dissipation from pavements, thereby improving traffic safety and reducing the long-term costs of road traffic.