Recycled Plastics and Rubber for Green Roads: Case Study

• Correct management of end-of-life tires and waste plastics is critical, but both wastes can be an excellent addition to pavement materials.
• The structural transformation of crumb rubber into devulcanized rubber (DVR) can solve the high-viscosity typical of rubberized bitumen, but its performance is poor.

• Composites of devulcanized tire rubber and waste plastics can enhance bitumen performance while using two waste materials at the same time.

• The rutting and fatigue cracking performance of bitumen modified with these composites is comparable to heavily SBS-modified bitumen, aka high-polymer modified bitumen.

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.