Bitumens modified with recycled polymers

Increasing traffic loading and volumes on roads has led to the use of polym er modified binders to improve the performance of bitumen in terms of addit ional strength, durability and increased resistance to rutting and fatigue cracking. Generally those modifiers currently in use are virgin polymers bu t the research investigates the possibility of using waste polymers instead . The aim was to find a recycled polymer modified binder that would be simi lar to a proven modified binder (Polyflex 75) or would augment the properti es of 100 penetration grade bitumen. A wide range of recycled polymers was tested including polyethylenes, polyp ropylenes, polyetherpolyurethane, ground rubber and truck tyre rubber. Alth ough there were some problems with stability in the bitumen some were found to be successful. The blend with 3% by mass of low density polyethylene su bstituted for 1% by mass of sytrene butadiene styrene had similar propertie s to that Polyflex 75 although it had a lower stiffness. A combination of e thylene vinyl acetate with low density polyethylene showed similar viscosit y to that of a 100 penetration bitumen while hating an increased softening point. The blends showing promise need to be subjected to further investiga tion. in particular to evaluate how those blends perform in optimised bitum inous mixes.