PANI–CS polymer blend for durable RAP-containing asphalt mixtures with reduced environmental impact

This study investigates the influence of a polyaniline–chitosan (PANI: CS) polymer blend used as a dual-functional additive on the rheological, aging, fatigue, and performance properties of bitumen binders and asphalt mixtures. Two road bitumens (70/100 and 50/70) were modified under different technological conditions and evaluated using conventional physical tests, aging simulations, and fatigue characterization based on the Linear Amplitude Sweep (LAS) method combined with the Viscoelastic Continuum Damage (VECD) model. Asphalt mixtures produced using hot mix asphalt (HMA) and warm mix asphalt (WMA) technologies containing reclaimed asphalt pavement (RAP) were also analyzed in terms of volumetric properties, moisture resistance, stiffness modulus, and environmental performance using a screening life cycle assessment. Modification with the PANI: CS blend resulted in a 23–38% reduction in penetration and a moderate increase in softening point, indicating controlled stiffening of the binder. The modified binders exhibited improved resistance to short- and long-term aging and showed reduced susceptibility to oxidative hardening. Fatigue analysis demonstrated that mixing temperature and conditioning time significantly influence damage initiation and crack propagation. Asphalt mixtures with the modified binder satisfied specification requirements, while screening life cycle assessment indicated a 16% reduction in global warming potential and about 30% reduction when normalized to service life.