Thermal regulation and molecular stabilization mechanism of composite phase change material modified cement-emulsified asphalt

Increasing extreme heat events have intensified heat accumulation in urban environments, exacerbating urban heat island effects and reducing outdoor thermal comfort, thereby creating an urgent demand for thermally regulated infrastructure materials. Here, we develop a high-density polyethylene (HDPE) supported PA (paraffin) composite phase change material (CPCM) to simultaneously improve structural stability and thermal regulation performance of cement-emulsified asphalt (CEA) in road applications. Molecular dynamics simulations reveal that HDPE effectively suppresses PA migration through intermolecular interactions and polymer chain entanglement, thereby enhancing CPCM stability at elevated temperatures. The optimized CPCM-CEA composite exhibits a pronounced thermal regulation effect, requiring 120 min longer to reach 50°C and maintaining a 4.3°C lower surface temperature than the control specimen under identical heating conditions. This work provided a framework for designing thermally regulated pavement materials for mitigating heat accumulation in urban environments.