Devulcanized Tire Rubber–Waste Plastic Compounds: A Solution to Improve Storage Stability of Plastic-Modified Bitumen

Recycled and post-consumers waste plastics have recently emerged as potential polymer modifiers of bitumen with the goal of reducing costs and environmental impacts associated with asphalt production. However, field applications have been limited by storage stability concerns due to poor bitumen–plastic affinity. A new compound obtained with a chemo-mechanical blending process of devulcanized tire rubber (DVR), waste plastics (low-density polyethylene (LDPE) and polypropylene (PP)), and a set of proprietary chemicals is proposed to mitigate phase separation during storage. The rheological characterization of bitumen modified with the new compounds consistently indicated improved stability compared to bitumen produced by adding either plastics or DVR only. The simultaneous addition of non-compounded DVR and plastics did not reach satisfactory results in terms of phase separation. Hence, enhancement can be attributed to plasticizers and compatibilizers agents added during the production process of the new materials. Calorimetric and Fourier Transform Infrared (FT–IR) characterizations showed minor differences between the use of DVR–LDPE and DVR–PP compounds, with the former to be preferrable.