Potential of Using Bio-oil as a Partial Replacement of Asphalt Binder: Chemical and Fatigue Analyses

This study aims to partially replace the conventional asphalt binder with a bio-oil to achieve a novel and sustainable value chain for paving materials commonly used in Nordic countries. For this purpose, the penetration and softening point of bituminous binders were measured to determine the optimum replacement rate of bio-oil. Fourier-transform infrared spectroscopy (FTIR) and linear amplitude sweep (LAS) test were used to evaluate the chemical and fatigue properties of the bio-extended binder. The results indicate that penetration and softening point values have an exponential and linear relation with the bio-oil content, and the optimum replacement rate was determined as 6%. The infrared spectra show that the chemical composition of the bio-extended binder is largely similar to that of the target asphalt binder while exhibiting new weak peaks due to the addition of bio-oil. The bio-extended binder showed inferior fatigue performance to the target asphalt binder, which raises concerns about the selection of bio-oil, formulation of bio-extended binder, etc. In summary, the use of bio-extended bituminous binder can be practicable. Still, proper bio-oil selection and formulation should be guaranteed, and the binder material behavior needs to be evaluated beyond the conventional penetration and softening point tests.