Performance and Sustainability Assessment of Environmentally Friendly Additives in Asphalt Pavements

Due to the limitation of natural resources and population growth, the increasing consumption of non-renewable resources has accelerated their rapid depletion. Pavements are one of the main consumers of resources. In this study, five categories of environmentally friendly additives including photocatalysts, recycled materials, nanomaterials, and natural fibers have been analyzed based on a review of studies from the last two decades. The findings show that titanium dioxide, with its high nitrogen oxide removal efficiency, is the most effective photocatalyst. Crumb rubber at 15% by weight increases the rutting parameter (G*/sinδ) by up to 680%, but worsens the fatigue parameter (G*×sinδ) by up to 320%. SBS polymer at 4% improves rutting resistance by 140% while also increasing fatigue resistance by 5%. Natural fibers (hemp, coconut, goat wool) increase toughness by up to 30%, making them a suitable alternative to synthetic fibers. Among nanomaterials, nanosilica at 7% improves the rutting parameter by up to 319%. Gilsonite and polyphosphoric acid additives, with 450% and 200% increases in the rutting parameter respectively, are effective options for heavy-duty applications. However, nanosilica and gilsonite reduce fatigue resistance by 28% and 95% respectively, while polyphosphoric acid has no negative effect on fatigue. The conscious selection of additives based on local conditions and attention to the rutting-fatigue trade-off is the key to achieving sustainable pavements, and it can create positive economic and environmental impacts in the pavement industry while reducing pressure on natural resources.