Abstract Lignin is one of major by-product from wood and paper industry. As natural biopolymer, it could be a valid alternative as bitumen replacement and/or modifier to enhance the relevant performance of asphalt mixtures, promoting concurrently environmental benefits. In this context, the study focused on the effects of two different binders containing 30 of lignin (by weight) on the mechanical properties of bio-asphalt mixtures. Specifically, two different lignins were blended with two plain bitumens having different consistencies so obtaining two bio-binders with a similar consistency to that of a reference plain bitumen. The two bio-binders and the reference bitumen were used to produce in the laboratory three dense graded asphalt mixtures for binder courses according to the Italian Technical Specifications. The binder-aggregate adhesion, Indirect Tensile Strength, Stiffness Modulus, thermal susceptibility, fatigue resistance, and low-temperature cracking of mixtures were analysed in both unaged and long-term aged conditions. Overall, this investigation demonstrates that bio-mixtures containing lignin offer comparable results to the reference asphalt mixture. Moreover, the bio-asphalt mixtures exhibit a lower thermal susceptibility, as well as lower aging susceptibility. The findings of this research highly encourage the use of lignin as partial replacement of bitumen in asphalt pavements.
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