Optimization of Hot Mix Asphalt Using Diesel Engine Waste Oil and Reclaimed Asphalt Pavement to Improve Stability and Durability

The demand for conventional pavement materials is increasing daily. This high demand has led to the scarcity and rising prices of materials such as bitumen and virgin aggregates. Consequently, alternatives to conventional (virgin) materials in asphalt mixtures are becoming a growing concern. The primary aim of this research is to evaluate the potential of using diesel engine waste oil (DEWO) as a rejuvenator for hot mix asphalt (HMA) modified with reclaimed asphalt pavement (RAP). The RAP used in this study was rejuvenated with virgin bitumen modified with DEWO in proportions of 2%, 4%, and 6% of the virgin bitumen. The rejuvenated RAP was then added to the HMA in proportions of 20%, 40%, and 60% to assess its mechanical performance. The addition of RAP to the HMA yielded the highest Marshall stability at 40% RAP and 4% DEWO, representing a 41% improvement compared to the unmodified HMA. The Marshall flow decreased by 1% for all RAP proportions, except at 6% DEWO, where it increased by 3%. The air voids and bulk density of the mixture were within the acceptable limits of standard specifications for all RAP proportions. Additionally, the mixture showed a maximum improvement of 19% in resistance to moisture damage and a significant 89% increase in resistance to punching load at 40% RAP and 4% DEWO. Therefore, it is concluded that HMA containing RAP can be effectively modified with DEWO to meet relevant durability and volumetric performance requirements.