Rheological and mechanical performance of hot-mix asphalt with bitumen partially replaced by lignin recovered from paper industry waste

Abstract Asphalt binders are among the most widely used non-renewable resources in the construction, maintenance and operation of road infrastructure. This has intensified the search for alternative materials capable of partially replacing bitumen, encouraging research into renewable resources and industrial residues as more sustainable options. This study evaluates the maximum practical incorporation of lignin as a partial bitumen substitute, with emphasis on lignin recovered from black liquor waste (LBL) from a Peruvian paper-industry plant. An 85/100 penetration-grade binder was partially replaced with commercial lignin (CL) and LBL, selecting dosages of 10% CL and 8.5% LBL by binder mass as the most stable incorporation levels capable of upgrading performance towards behaviour comparable to 60/70-grade bitumen. Binder testing (rotational viscosity, DSR/RTFO, MSCR and BBR) and mixture performance evaluation (volumetrics, moisture susceptibility, Hamburg wheel-tracking, dynamic modulus and IDEAL-CT) were conducted. CL improved high-temperature rutting resistance and achieved a higher MSCR traffic grade (“E”), whereas LBL met specification requirements with a grade comparable to the control (“V”). All mixtures satisfied volumetric criteria and achieved TSR values above 0.80, with rutting performance remaining within the acceptance criterion. Dynamic modulus master-curve analysis indicated that LBL exhibits lower mixture stiffness at elevated temperatures than the control, consistent with its higher rutting susceptibility. Although IDEAL-CT results showed reduced cracking tolerance in lignin-containing mixtures relative to the control, overall the findings demonstrate the technical feasibility of valorising black-liquor-recovered lignin as a partial bitumen replacement in asphalt mixture design.