Desulphurisation of waste rubber powder using mechanochemical method and the influence on modified asphalt

The desulfurization treatments are vital for recycling waste rubber powder (WRP). The mechanochemical method accelerates desulfurization activation of additives, enhancing WRP's surface roughness and activity. This study employed mechanochemical desulfurization to produce desulfurized waste rubber powder (DWRP) modified asphalt. Variables like desulfurizer content, mixing temperature, and time were examined during the desulfurization process. Results revealed that organic disulfide (OGDS) had minimal impact on rubber's main chain but significantly affected sulfur cross-linked bonds. Optimal desulfurization conditions for OGDS were determined: 3.0% content, 140°C temperature, and 30 min mixing time. Scanning electron microscopy illustrated the destructive micromorphology of DWRP, featuring irregular surfaces with numerous holes or protrusions. DWRP-modified asphalt exhibited enhanced properties: a 44% increase in 5°C ductility, a 57% reduction in 180°C viscosity, and a 75% decrease in segregation softening point difference.