Novel Asphalt-Mix Design with High Thermal Diffusivity for Alleviating the Urban Heat Island

Abstract

Excessive surface temperature of asphalt pavement in summer is one of the main causes of urban heat islands (UHIs), so reducing pavement temperature is a potential research perspective for alleviating the UHI effect. This paper proposes a new type of asphalt-mix design. The thermal diffusivity of asphalt pavement is effectively enhanced by replacing the limestone coarse aggregate (LCA) of traditional asphalt mixture with quartzite coarse aggregate (QCA) with high thermal conductivity, which accelerates the heat diffusion of pavements to reduce the pavement temperature and the air temperature near the ground. By designing the material composition of high thermal diffusivity asphalt concrete (HTD-AC) with different replacement ratios of QCA, the asphalt concrete achieves a higher thermal diffusivity than traditional asphalt concrete. In addition, the mechanical properties of QCA and its adhesion to asphalt were tested. It was proved that the QCA meets road requirements, and QCA can be used in the preparation of HTD-AC. Moreover, asphalt pavement with high thermal diffusivity was verified to have good service performance, which effectively guarantees the quality and safety of urban traffic.