Thermal and Rheological Characteristics of Phase Change Materials in Asphalt Binder with an Extended Thermoregulation Range

Microencapsulated phase change materials (MPCMs) represent an innovative solution to potentially enhance performance of an asphalt binder and control rapid temperature fluctuations. However, the thermoregulation process primarily occurs within a limited range around the melting point of an MPCM. Thus, extending the thermoregulation range of MPCMs is necessary for improving the performance of asphalt binder across a wide range of temperatures. For this purpose, two MPCMs (melting points: 6°C and 28°C) were combined into M6+M28 (1:1), and these were blended into base binders at dosages of 5%, 10%, and 20%. Then, samples were evaluated for thermoregulation range, long-term effective transfer, and survivability through thermal profiles and enthalpy ratios at different aging levels. Rheological validation involved determining the percentage change in complex modulus (G∗) and phase angle (δ). The performance of combined MPCMs within the thermoregulation range was assessed using fatigue factors determined by a pressure aging vessel, overall rutting resistance via G∗ and δ measured by a rolling thin film oven, and overall fatigue cracking resistance using the Glover-Rowe parameter. Results showed that M6+M28 at any dosage and binder type controlled the stiffness and viscoelastic properties within an extended range of -12°C to 33°C, compared to -12°C to 16°C and 10°C to 33°C for individual MPCMs. The thermal stability of the combined MPCMs was found decrease with aging except in the soft grade binders at higher dosages. Additionally, M6+M28 improved the cracking performance within the thermoregulation range for both PG 58-28 and PG 64-22 binders, though the dosage impact varied. The Glover-Rowe parameter indicated improved fatigue cracking resistance at any dosage and for both binder types, whereas rutting resistance was enhanced only for PG 58-28 binders at any dosage.