Enhanced Thermal Insulation of Steel Slag Based on Ultrathin Friction Course with Ceramic Fiber

Rutting distress and urban heat island effects correlated to high temperatures negatively affect asphalt pavement, so reducing pavement temperature and heat absorption is necessary. This study developed a thermal insulation friction course (TIFC) made of steel slag (SS), limestone, and ceramic fiber (CF). Stone matrix asphalt (SMA)-5 asphalt mixtures with various CF contents and aggregate types were used as the TIFC. Pavement performance and thermal constants were tested. Cooling and heat insulation performance in the laboratory and outdoors were conducted through infrared temperature image characterization, respectively. Corresponding heat absorption was then calculated. Results showed that SS and lower CF result in lower volume performance. SS can enhance TIFC's higher skid resistance. The highest moisture resistance and interlayer shear strength appeared when SS and 2% CF were employed. SS and CF reduced the asphalt mixture's temperature and heat absorption. TIFC with SS and 2% CF showed the lowest heat conductivity, diffusivity, and maximum interlayer shear strength. TIFC with SS and 2% CF also showed maximum cooling effects. TIFC will help to address rutting and urban heat island effects, which is beneficial for road engineering and environmental sustainability.