Life cycle assessment of eco-friendly asphalt pavement involving multi-recycled materials: A comparative study

In this research, a comparative Life Cycle Assessment (LCA) is conducted to evaluate the environmental potential of utilizing multi recycled materials in asphalt pavement construction. These Materials are Reclaimed Asphalt Pavement (RAP), Off-spec Fly Ash (OFA), and a Food Waste Bio-oil (FWBO). A comparative analysis is performed on producing one ton of asphalt mixture considering multiple scenarios, which stem from virgin materials extraction, recycled materials production, transportation, and asphalt mix production. The study analyzed six percentages of RAP replacement to aggregate and asphalt binder, 0%, 15%, 30%, 50%, 80%, and 100% RAP. Moreover, two proposed products substituted 11% virgin asphalt binder by weight in the different mixtures. The first product is the FWBO, which is utilized alone as an asphalt binder rejuvenator with the highest two RAP rate scenarios: 80 and 100%. The second product is a blend of the OFA with the FWBO with a 2:1 ratio, which is evaluated with all the investigated scenarios. After assessing the baseline scenario, two alternative scenarios are investigated. The first alternative is utilizing natural gas to replace the commonly used Heavy Fuel Oil (HFO) in the asphalt mix production process. The second alternative scenario is changing the FWBO extraction technique from Soxhlet to Ultrasonic Assisted-oil Extraction (UAE). Open-LCA software is used for modeling all the investigated scenarios in the light of TRACI v.2.1 impact assessment methodology in this case study. The results show a reduction in environmental impacts with RAP utilization and the new eco-friendly products. Shifting asphalt mix plant fuel to natural gas instead of HFO offers considerable potential environmental benefits. Adopting the UAE as FWBO rejuvenator extraction method showed less energy and solvent consumption than the Soxhlet extraction, resulting in less environmental impacts.