Development of sustainable asphalt crack sealing materials using microwave-pyrolyzed polypropylene and recycled rubber: an experimental and molecular dynamics study

Effective crack sealing materials are crucial for maintaining asphalt pavements. This study introduces a sustainable crack repair material combining recycled crumb rubber (CR) and pyrolyzed polypropylene (PP). The integration of laboratory characterisation and molecular dynamics (MD) simulations provides a multi-scale perspective. The microwave pyrolysis of PP generates smaller molecular fragments and cross-linked structures, significantly enhance the mechanical and field performance of the sealants. Laboratory experiments were used to determine the optimal proportions of PP and CR. The CRPA-20/5 asphalt sealant formulation exhibits the best performance, with an SPD value of 3.1°C, excellent flexibility, and superior aging resistance, showing a 27.81% improvement in adhesion. MD simulations revealed that pyrolyzed PP promotes uniform dispersion of CR molecules, enhancing interfacial bonding with the crack surface, offering new insights into molecular-level interactions. This method provides environmental benefits while extending the lifespan of the road surface, offering a cost-effective and sustainable solution for road maintenance.