RECYCLED POLYMERS FOR USE AS BITUMEN MODIFIERS

The volume of waste polymer being produced continues to rise. Disposal is difficult and waste exceeds acceptable levels. The purpose of this research is to examine the possibility of incorporating waste polymer into bitumen as a modifier. The aim was to find recycled polymer modified binders that would be similar to proven modified binders or that would augment the properties of 100 penetration grade bitumen. A wide range of recycled polymers were tested, including polyethylenes, polypropylenes, polyetherpolyurethane, ground rubber, and truck tire rubber. Tests included viscosity, penetration, softening point, aging, and rheology. Stiffness tests on samples of bituminous mixes made using a selection of binders also formed part of the research program. Although stability problems were evident with some recycled modified bitumen, some cases were found to be successful. The blend with 3% low density polyethylene substituted for 1% styrene butadiene styrene had similar properties to that of Polyflex 75, although it had lower stiffness. The most impressive was a combination of low density polyethylene, bitumen, and ethyl vinyl acetate.