US Patent 11279811 Polymer-modified asphalt with wax additive

An improved method forms and employs a wax to modify asphalt. The method includes: (a) selecting a solid polymeric material, (b) heating the solid polymeric material in an extruder to produce a molten polymeric material, (c) filtering the molten polymeric material, (d) placing the molten polymeric material through a chemical depolymerization process in a reactor to produce a depolymerized polymeric material, and (e) adding the depolymerized material to a pre-wax mixture to produce a polymer-modified asphalt. The addition of wax reduced the mixing time necessary to achieve improved polymer dispersion compared to the control formulation modified bitumen and reduced the viscosity of the neat bitumen. Pre-polymer addition of wax is detrimental to most properties of the resulting modified asphalt. Post-polymer addition improved viscosity reduction, higher softening point and improved dimensional stability.