This paper proposes a unique, and proprietary, combination of a polyethylene and an elastomer for the modification of paving asphalts in order to minimize low temperature cracking and reduce rutting at elevated seasonal temperatures under heavy loads. A key objective of the research was to demonstrate the effectiveness of recycled polyethylene (PE) as a material for the modification of paving asphalts. The results indicate that the technology has the potential to create a sustainable downstream market for the safe diversion of large amounts of low grade post consumer polyethylene. Minor contaminants and mixed coloration of these waste materials pose difficulties for many potential applications but show no significant adverse effects on the quality of the modified asphalts. In addition to creating an important outlet for waste plastics, substantial material cost savings are possible over virgin polyethylene.

Asphalts modified by this process contain polyethylene particles which remain emulsified by an elastomeric steric layer. The liquid emulsion remains permanently stable at elevated temperatures and is not adversely affected by repeated heating/cooling cycles.

The low temperature fracture toughness of several asphalts modified with different grades of polyethylene was improved at temperatures near -20°C when compared to that of unmodified asphalt and another polymer modified asphalt. These same compositions also exhibited greater stiffness and elasticity at elevated temperatures near 60°C. Mix design and performance for selected stabilized PE modified binders were also enhanced when compared with unmodified asphalt.

The incentive for this research is the prospect of paved roads having substantially longer service lifetimes using environmentally neutral waste polyethylenes as modifiers.