The effect of base bitumen properties on the performance of bitumen blends containing higher dosages of bio-ethanol industry-based lignin

The objective of this study is to assess the influence of different base bitumen types on the properties of lignin–bitumen blends containing high dosages of bio-ethanol industry-based lignin. It also evaluates the feasibility of formulating blends with up to 30% lignin. Partial replacement of base bitumens (VG40, VG30, and VG20) with 20% and 30% lignin by weight was carried out. The chemical characteristics of the resulting blends were analyzed using CHNS analyser (carbon, hydrogen, nitrogen, and sulfur), Fourier-transform infrared spectroscopy (FTIR), and thin-layer chromatography with flame ionization detection (TLC-FID). In addition, the blends were evaluated for stripping resistance, rheological behavior, aging index, rutting resistance, and fatigue performance. The relationship between the chemical composition and rheological properties of the base bitumen and the corresponding lignin–bitumen blends was also examined. The results indicate that blending bio-ethanol industry-based lignin with different base bitumens up to 30% is primarily a physical process. However, the chemical composition of the base bitumen significantly affects the elemental composition and colloidal structure of the blends. Physical properties such as softening point and viscosity, |G*|/sinδ, rutting resistance (J_nr), and moisture damage resistance are not significantly influenced by the base bitumen type. In contrast, separation, aging index, percent recovery, and fatigue life strongly depend on the base bitumen's colloidal structure and lignin dosage. While bitumen blends with higher dosages of lignin (up to 30%) are feasible using softer-grade bitumens, a slight compromise in fatigue performance may be expected due to microstructural discontinuities.