Sustained-thermal-regulation composite PCMs using porous waste-derived support and epoxy encapsulation for enhanced thermal resilience of asphalt pavements

Polyethylene glycol (PEG) has been widely recognized as a promising phase-change heat storage material for enhancing the high-temperature adaptability of asphalt pavements. However, PEG tends to leak during melting, which compromises pavement performance and long-term functionality. To address this issue, a dual strategy combining vacuum impregnation and epoxy encapsulation was developed to prepare composite phase-change materials (cPCMs) with high latent heat and anti-leakage properties. PEG was first adsorbed into porous carriers via vacuum impregnation and subsequently encapsulated with epoxy resin. Various carrier-supported cPCMs were incorporated into asphalt for comparative evaluation. The composites were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TG), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and leakage tests, while the modified asphalts were evaluated by DSC, conventional tests, dynamic shear rheometer (DSR), and bending beam rheometer (BBR). Results showed that epoxy encapsulation significantly enhanced integrity and durability. Among all carriers, red-mud-based cPCM exhibited the highest latent heat of 135.54 J/g, zero leakage after 100 thermal cycles, and superior thermal stability with only 0.11% mass loss at 250 °C. The corresponding phase-change asphalt demonstrated excellent temperature-regulating capability and met pavement performance requirements under both high- and low-temperature conditions. Overall, this dual strategy effectively realizes long-term thermal regulation for asphalt pavements and promotes the sustainable reuse of solid waste materials such as red mud, offering a green and durable solution for smart, energy-responsive road systems.