Bituminous Binder and Bituminous Mixture Modified with Waste Polyethylene

RILEM TC-279 WMR task group TG 1 studied the performance of waste Polyethylene (PE) in bituminous binders and bituminous mixtures. Several laboratories participated in this study following a common protocol. Locally sources aggregates and bituminous binder and same source of waste PE were utilized. The binder experiments showed that at high temperatures, using MSCR tests, PE modified blends had better resistance to permanent deformation in comparison to the non modified binder. Whereas at intermediate temperatures, using the LAS tests, fatigue performance of the PE blends could withstand more loading cycles under low strains; however, it could sustain less loading cycles under high strains due to the increase in brittleness. Dry process was used for the mixture experiments in order to bypass the stability and inhomogeneity experience that was observed at the binder scale. The PE modified mixtures showed improved workability and increased strength. The higher the PE dosage, the higher the ITS increase with respect to the values measured for the control materials (i.e., without any plastic waste) thanks to the improved cohesion of the plastic modified mastic. The stiffness experiments tended to show an improved performance with a lower time dependence and a higher elasticity when plastic was added. The cyclic compression tests demonstrated a reduced creep rate along with a higher creep modulus thanks to the addition of PE; similar conclusions can be drawn from the experimental findings coming from wheel tracking test. Furthermore, acceptable and often improved moisture resistance was observed for PE modified materials.