Bitumens Modified with Recycled Polymers

Increasing traffic loading and volumes on roads has led to the use of polymer modified binders to improve the performance of bitumen in terms of additional strength, durability and increased resistance to rutting and fatigue cracking. Generally those modifiers currently in use are virgin polymers but the research investigate the possibility of using waste polymers instead. The aim was to find a recycled polymer modified binder that would be similar to a proven modified binder (Polyflex 75) or would augment the properties of 100 penetration grade bitumen. A wide range of recycled polymers was tested including polyethylenes, polypropylenes, polyetherpolyurethane, ground rubber and truck tyre rubber. Although there were some problems with stability in the bitumen some were found to be successful. The blen with 3% by mass of low density polyethylene substituted for 1% by mass of styrene butadience styrene had similar properties to that of Polyflex 75 although it had a lower stiffness. A combination of ethylene vinyl acetate with low density polyethylene showed similar viscosity to that of a 100 penetration bitumen while having an increased softening point. The blends showing promise need to be subjected to further investigation, in particular to evaluate how these blends perform in optimized bituminous mixes.