Long-term performance of asphalt mixtures containing bio-extended bituminous binders: laboratory investigation and accelerated pavement testing

Bio-extended bituminous binders were formulated with tall oil pitch (TOP). Their corresponding asphalt mixtures were prepared. Various laboratory tests and full-scale accelerated pavement testing (APT) were conducted to evaluate their long-term performance. It is indicated that, at 25°C, the aged bio-extended 70/100 binder with 5% TOP had similar fatigue resistance to its reference. At 10°C, the aged bio-extended 160/220 binder with 21% TOP was marginally less resistant to fatigue at small strains. The asphalt mixture with bio-extended 160/220 binder had higher stiffness at 10°C and similar water sensitivity to its reference. Although the aged mixture with bio-extended binder showed higher strength to resist cracks at 5°C, it was more brittle, leading to faster crack propagation. After further moisture conditioning, the mixture became weaker but less brittle. The full-scale APT indicated that the section with bio-extended binders was more resistant to permanent deformation. Overall, the results suggest potential for larger-scale testing.