Storage stability and high-temperature performance of asphalt binder modified with recycled plastic

Huge amounts of generated non-degradable plastic wastes constitute a major global environmental nuisance. The combined annual municipal solid waste (MSW) generation of Saudi Arabian Kingdom (KSA) exceeds 14,000,000 tonnes, with an average per capita of 1.4 kg/day. Plastic wastes constitute up to 10% of these MSW. The local asphalt can only perform satisfactorily without polymer modification in an environment with a maximum pavement temperature below 64°C. But the 7-day maximum pavement temperature ranges between 64°C and 76°C within the Kingdom. Dynamic storage stability, high-temperature performance, non-recoverable creep compliance (Jnr), and strain recovering tendency of recycled high- and low-density polyethylene (RHDPE and RLDPE), and recycled polypropylene-(RPP) modified asphalt binders in combination with styrene–butadiene–styrene (SBS) and polybilt (PB) were presented in this study. Improved high-temperature performance was observed. Even though the recycled plastic waste-modified binders lack sufficient strain recovering ability, RLDPE and RHDPE could be utilised along with an elastomeric SBS to achieve a higher recovery and strain resistance, than that which could be achieved if the same amount of SBS alone is used. RPP content above 2% will lead to an unstable modified asphalt binder. The RHDPE content below 4% and the RLDPE content below 6% whether containing either SBS or PB have shown good storage stability trait under mild agitation, in terms of both time degradation and separation.