Recycled plastics and rubber for green roads: The case study of devulcanized tire rubber and waste plastics compounds to enhance bitumen performance

Devulcanized rubber (DVR) and waste plastics have been studied separately as bitumen modifiers, but their individual drawbacks prevent full implementation in the field. In this paper, two pelletized composites produced by coupling DVR with waste low-density polyethylene (LDPE) and polypropylene (PP) were investigated. Linear viscoelastic properties, rutting, and fatigue cracking performance were evaluated, and results were compared to those obtained on neat and polymer-modified bitumen with high styrene-butadiene-styrene content (HiPMB). The non-recoverable creep compliance was reduced with the increasing addition of DVR with either LDPE or PP, and the modified bitumen can be classifiable as “E” grade like the common HiPMB. Bitumen modified with DVR-LDPE compounds showed the best fatigue cracking performance overall, and can fully replace the industrial HiPMB. The implications of these results go beyond the sole performance improvement since these compounds can significantly reduce the environmental impact of road construction by using two waste materials simultaneously.