The main objective of this study was the investigation of the characteristic properties of lignin-modified bitumen with different lignin contents. Three (3) blends with different lignin contents (5%, 10% and 15% by weight of bitumen) were produced. Characteristic properties such as penetration, ring & ball, elastic recovery, force ductility, dynamic viscosity and storage stability were determined for the reference bitumen and the three lignin blends. Furthermore, the results of the tests were utilized to calculate the Penetration Index (PI), Activation Energy (Ea), Viscosity-Temperature Susceptibility (VTS) Index and Mixing Temperature (Tmixing) along with their respective Pearson’s Correlation Coefficient (PCC), R2 and p-values. The main conclusion was that Kraft lignin powder hardens the conventional bitumen. Specifically, the addition of 15% lignin to the bitumen hardened the blend to such a degree that the bitumen changed category from 50/70 to 35/50 with respect to EN 12591. Additionally, a strong linear statistical correlation was observed between Ea and VTS Index suggesting that these values should be taken into consideration when characterizing the temperature susceptibility of bio-modified bitumen.

Bio-binder; Bio-bitumen; Lignin