Polymer-Based Flame-Retardant Asphalt: A Comprehensive Review of Materials, Performance, and Evaluation Methods

The growing demand for durable, fire-resistant, and sustainable pavements has intensified research on asphalt as a polymeric composite system. This review provides a comprehensive analysis of asphalt from the perspective of polymer science, focusing on (1) material composition: asphalt chemistry and polymer-binder interaction, and the introduction of polymer modifiers; (2) material properties: rheology, thermal stability, mechanical properties and flame retardancy; and (3) evaluation methods: derivative thermogravimetric analysis, cone calorimeter, scanning electron microscope and computer simulation. Applications in road infrastructure, industrial surfaces, and high-temperature environments are discussed, emphasizing how polymer modifications enhance performance under operational stresses. Evaluation methodologies, including wheel-tracking tests and thermogravimetric and derivative thermogravimetric analysis, are critically reviewed to quantify deformation, thermal degradation, and fire-resistance mechanisms at both microstructural and molecular levels. Several key challenges remain, including understanding the long-term interaction between polymers and asphalt, optimizing the dispersion of reinforcing materials, and maximizing the performance of recycled polymers. This review aims to guide future research on polymer-modified asphalt systems to achieve safer, more durable, and more sustainable pavement solutions.