Comparative analysis of the rejuvenation effect of waste engine oil bottom from different recycling processes on aged asphalt

This study systematically compares the rejuvenation mechanisms and efficacy of waste engine oil bottom (WEOB) residues obtained via distillation and membrane filtration for rejuvenating aged asphalt. A series of experiments—including SARA (saturates, aromatics, resins, and asphaltenes) fractionation, dynamic shear rheometry (DSR), gel permeation chromatography (GPC), and atomic force microscopy (AFM)—were conducted to characterize the chemical composition, rheological properties, molecular weight distribution, and micromorphology of both types of WEOB and the resulting rejuvenated asphalt. The results reveal that the rejuvenation mechanism primarily relies on supplementation and dilution by low-molecular-weight components (saturates and aromatics), coupled with capability for dissolution and dispersion of asphaltene aggregates. Both types of WEOB effectively restored the penetration, softening point, and rheological properties of the aged asphalt, bringing the aged asphalt’s macro-performance and microstructure closer to those of virgin asphalt. Notably, WEOB derived from membrane filtration (MWEOB) demonstrated superior rejuvenation performance compared to distillation-derived WEOB (DWEOB). However, due to the limited capacity of WEOB to dissolve and disperse aged asphaltene aggregates, the recovery of ductility in the rejuvenated asphalt remained suboptimal. These findings provide theoretical support for optimizing process selection and engineering applications of WEOB-based rejuvenating agents.