Microencapsulated Phase Change Material in Asphalt for Urban Heat Island Mitigation: A Critical Review of Laboratory-Based Experimental Evidence.

Abstract

Urban heat island (UHI) intensification is strongly associated with dark, impervious pavements that absorb, store, and re-radiate solar energy. Among emerging pavement-cooling strategies, phase change materials (PCMs) offer a latent-heat-based mechanism for moderating thermal peaks without relying solely on reflectivity or permeability. In asphalt systems, however, direct PCM incorporation is constrained by leakage, incompatibility with bitumen, and thermo-mechanical instability during mixing and service. Microencapsulation has therefore emerged as a leading strategy because it protects the PCM core, improves dispersion, and enhances thermal durability. By analyzing laboratory-based literature on microencapsulated PCM (MPCM) integrated into asphalt binders and asphalt mixtures, this study evaluates the effectiveness of MPCM in asphalt, its performance in the management of pavement heat, thermal regulation performance, mechanical implications, and research gaps.