Abstract
This study examines the effect of cationic bio-based adhesion promoters (APs) derived from rapeseed oil (RO) on the performance of bitumen and asphalt mixtures. Several synthesized APs with varying polyamine content were evaluated and compared with commercial additives (Wetfix® BE, Nouryon, Netherlands and Carbazole AK-M, SPETSKONTRAKT, Kyiv, Ukraine). Modification of bitumen with bio-based APs improved adhesion to glass and crushed stone while keeping penetration, softening point, and ductility within standard limits. Among the tested formulations, AP20 demonstrated the most balanced performance, achieving high adhesion values even at low dosages (0.2–0.4 wt. %). Asphalt concrete mixes prepared with AP20 exhibited enhanced water resistance and higher indirect tensile strength ratio (ITSR), indicating improved durability under moisture exposure. These findings highlight the potential of rapeseed oil-based adhesion promoters as effective and sustainable alternatives to conventional anti-stripping agents in road construction.