Applicability assessment of stearic acid/palmitic acid binary eutectic phase change material in cooling pavement

Abstract

Phase change materials are functional materials that have the potential to cool asphalt pavement. This study focuses on the design of a stearic acid/palmitic acid binary eutectic phase change material (SA/PA-PCM) and its utilization in asphalt binder by conducting a series of tests. The results show that the dislocation density, micro-strain, and crystallinity of SA/PA-PCM increase by approximately 432%, 140%, 6%, respectively, which means that it can have a more stable crystal structure. Therefore, the SA/PA-PCM has a higher phase transition enthalpy (226.9 J/g) and a better phase transition temperature (54.8 °C) than traditional materials. Moreover, no chemical reaction is detected in the eutectic and modified asphalt binder processes. Crystalline SA/PA-PCM has the potential to increase the anti-deforming capability of the binder, whereas liquid SA/PA-PCM suppresses the rheological behaviors. The decomposition temperature of SA/PA-PCM (approximately 200 °C) is higher than that of two kinds of individual fatty acids. Meanwhile, it is still above the traditional hot-mix asphalt pavement construction temperatures. Thus, we concluded that SA/PA-PCM has exceptional phase change characteristics and is applicable for use in cooling asphalt binder. Nevertheless, encapsulating technologies must be adopted to prevent the deleterious impact of the liquefiable phase change materials on the binder.