Development and characterization of a novel steel slag-based composite phase change aggregate for snow/ice melting of asphalt pavements

Abstract

Steel slag is a solid waste which originates frrom the steelmaking industry. Its improper disposal can cause serious environmental pollution and land encroachment. Currently, recycling steel slag as aggregate for asphalt paving has been identified as an emerging sustainable way to promote the secondary reuse of solid waste. However, the functional use of steel slag aggregates still needs further exploration to maximize its utilization efficiency. This study aimed to develop a novel steel slag-based composite phase change aggregate (SS-CPCA) for snow/ice melting of asphalt pavements. Firstly, a binary n-alkane eutectic system was established to determine the binary eutectic composite of PCMs. In combination with the DSC test results, the n-tetradecane and n-octadecane were screened out as the best binary eutectic composite, of which eutectic mass ratio, phase change temperature, and enthalpy were 84.4: 15.6, 2.87 °C, and 179.60 J/g, respectively. The SS-CPCA was then developed by using the coarse steel slag aggregate to adsorb the PCM composite while using the cement mortar as a coating. A type of SMA-13 asphalt mixture was subsequently selected and used for fabricating the SS-CPCA asphalt mixture. Finally, the pavement performance and temperature regulation performance of the SS-CPCA based asphalt mixture were tested and compared with those of the steel slag-based asphalt mixture. The test results indicated that the pavement performance properties of SS-CPCA asphalt mixture satisfied the specification requirements, verifying the feasibility of utilization of the SS-CPCA for asphalt paving. Moreover, it showed that the incorporation of SS-CPCA has the capability to increase the surface temperature of SMA-13 asphalt mixture as high as 3.4 ℃, while extending the cooling time to 780 s when the asphalt mixture surface temperature reaches 0 ℃. These findings demonstrate that the developed SS-CPCA has a promising snow/ice melting performance for asphalt pavements.