Partial Replacement of Fossil-Based Bitumen with Lignin from the Bioethanol Industry and Biooils

The objective of this study is to evaluate the partial replacement of fossil-based bitumen with lignin from the bioethanol industry and biooils. Two different biooils, waste cooking oil (WCO) and cashew nut shell liquid (CNSL), were incorporated at 1%, 3%, and 5% dosage (by weight of base bitumen), along with 20% bioethanol industry-based lignin as a partial replacement for the base bitumen. To assess the composite effect on base bitumen, the prepared blends were characterized for chemical composition (carbon, hydrogen, nitrogen, and sulfur analysis and Fourier transform infrared spectroscopy), physical properties, temperature susceptibility (viscosity), rheological properties, aging susceptibility (rheological aging index), rutting resistance (multiple stress creep and recovery), fatigue resistance (time sweep test), durability cracking (Glover-Rowe parameter test), and moisture damage resistance (rolling bottle test). The findings demonstrate that partial replacement of base bitumen with lignin and biooils is a physical process, and the biooils recovered the low molecular weight substances of lignin-bitumen blends, indicated by the increased hydrogen to carbon (H/C) ratio. Adding biooils with lignin improved fatigue life, cracking resistance, and moisture damage resistance, and reduced thermal susceptibility, regardless of type. Adding WCO reduces aging susceptibility, whereas CNSL increases it at higher dosages due to volatilization. Among the tested combinations, a 1% biooil blend provided acceptable rutting resistance and storage stability, while sustaining improvements in other key properties.