Multifaceted assessment of modifying and rejuvenating asphalt binders with recycled waste plastic and engine oil

This study tackles the environmental challenges associated with the growing accumulation of waste plastic (WP), specifically recycled low-density polyethylene (R-LDPE), by examining its impact on the performance of asphalt binders amid extreme weather and heavy traffic conditions. The research investigates how R-LDPE modifies both virgin asphalt binder (VAB) and recycled asphalt binder (RAB) rejuvenated with 15% waste engine oil (WEO). Three proportions of R-LDPE (2%, 3%, and 4% by weight of VAB) were evaluated, with findings indicating that 2% is the optimal amount for enhancing binder properties. The study involved morphological, thermal, and chemical evaluations using scanning electronic microscope (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Additionally, comprehensive rheological and mechanical properties were assessed, including tests for penetration, softening point, rotational viscosity (RV), dynamic shear at high and intermediate temperatures, multiple stress creep and recovery (MSCR), and linear amplitude sweep (LAS). The results revealed that R-LDPE incorporation significantly improves the thermal stability, stiffness, and rutting resistance of asphalt binders, with modified RAB outperforming VAB in rutting resistance, while fatigue resistance was optimized with 2% R-LDPE. The MSCR test results further revealed enhanced elastic recovery and reduced creep, indicating superior resistance to repeated loading. The LAS test indicated an improvement in fatigue life and better resistance to crack propagation under cyclic loading. Overall, the use of R-LDPE and WEO enhanced the investigated binder's durability and performance, making them more suitable for hot climates and high-stress applications.