| Abstrakt: |
The limitations and depletion of fuel reserves, escalation of costs, and adverse environmental impacts associated with using bitumen in road construction have highlighted the importance of investigating the efficacy of numerous viable substitutes for bitumen. This study aims to evaluate the impact of diverse bio-extenders as bitumen extenders on bitumen’s mechanical and environmental characteristics. After examining the concept of biomass, this study introduced biomass waste derivatives (bio-oils, lignin, and molasses) and their chemical structure. A thorough examination was conducted to assess the bio-extender’s effects on both the rheological properties of bitumen and the mechanical characteristics of asphalt mixtures. Then, a bio-extender type and quantity were put forth to align with established standards. Finally, a comparative analysis was conducted between the carbon dioxide emissions and associated costs of sustainable and conventional extenders. The findings indicate that many bio-oils positively influence the low-temperature performance of asphalt binders and mixtures but negatively influence their high-temperature performance. Bio-oil increases the physical characteristics, such as penetration by 30%, and reduces the softening point to 3℃. Due to the softening of asphalt bio-oil, the resistance against low-temperature cracking increases, and the resistance against rutting decreases. The optimal inclusion of lignin and molasses reduces penetration until 30% and increases the softening point by about 25%, which indicates a more resistant bitumen against temperature sensitivity. The rutting parameter (i.e., G*/sinδ) increases to 50%, and its fatigue life increases to 12% in optimal value. However, with the increase of the strain level, the fatigue life decreases. The low-temperature cracking resistance improves by 5%. The utilization of bio-oil may necessitate the incorporation of a modifier to counterbalance the inadequate high-temperature performance of bio-oil, owing to its lightweight constituents. The results indicate that using bio-extenders in bitumen can lower the costs and greenhouse gas emissions by about 40% and 20%, respectively. The study findings show that bio-extenders exhibit considerable promise as substitutes for petroleum bitumen. |
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