Assessing the direct interaction of asphalt binder with stearic acid/palmitic acid binary eutectic phase change material

• Crystalline SA/PA-PCM enhanced the rutting resistance of the asphalt. • SA/PA-PCM formed a stable layered structure system inside the binder. • The maximum temperature difference between the asphalt was 11.5 °C. • The temperature peak of the modified binders lagged behind 40 min. To achieve the practical application of the stearic acid/palmitic acid binary eutectic phase change material (SA/PA-PCM) as an asphalt additive for cooling asphalt pavements in the summer, this study aimed to explore the direct interaction of asphalt with SA/PA-PCM. A series of tests were implemented to analyze the chemical composition, microstructure, thermophysical and rheological behaviors and thermal regulating properties of the SA/PA-PCM-modified binders. The results showed that a binder with a higher content of crystalline SA/PA-PCM corresponded to greater elastic modulus, complex modulus, elastic recovery potential, and creep behaviors, suggesting a positive role for SA/PA-PCM in the high-temperature rutting resistance and low-temperature cracking resistance of asphalt. These results are ascribable to the fact that incorporating SA/PA-PCM reconstructed the chemical composition of asphalt and formed a stable layered structure system inside the binder. However, the liquefied SA/PA-PCM destroyed the internal layered structure in the modified binders, resulting in a double loss of elasticity and viscosity. Furthermore, SA/PA-PCM improved the specific heat capacity of the binder by approximately 20%. The distinguished temperature regulating property was reflected by the obvious temperature difference (max 11.5 °C) and temperature hysteresis (approximately 40 min) between the modified binder and the base binder.