Development of Statistical Models of the Effects of Waste Engine Oil (WEO) on Different Grades of Asphalt

This research examines the impact of Waste Engine Oil (WEO) as a modifier on the physical properties of asphalt binders across three different grades (40/50,50/60, and 60/70). The goal is to explore sustainable alternatives that enhance pavement performance and workability. Asphalt binders were modified with WEO at concentrations of (2%, 4%, 6%, 8%, and 10%) by weight and subjected to selected tests, including penetration, softening point, flash and fire points, and Rolling Thin Film Oven (RTFO) aging. To analyze the effect of WEO content quantitatively, second-degree polynomial regression models were developed for each test across the three grades. The results demonstrated that moderate additions of WEO (2-4%) significantly improved binder flexibility and penetration depth, facilitating better workability, especially in cooler climates. However, higher concentrations of WEO (above 8%) led to excessive softening, reduced thermal stability, and diminished resistance to aging. Despite noticeable reductions in flash and fire points, all modified binders met ASTM safety requirements. The study concludes that optimal WEO content ranges between (2-4%) for scenarios prioritizing long-term durability and thermal stability, while (4-6%) is suitable for applications emphasizing enhanced flexibility and workability. These findings underscore WEO’s potential as an environmentally sustainable and performance-enhancing asphalt binder modifier when applied within controlled limits.