Effects of bio-nano ashes and nano limestone on the tensile metrics and rheological parameters as a measure of bitumen performance

Early pavement deterioration remains a major challenge in asphalt pavement construction, primarily due to temperature-induced distresses such as rutting and fatigue cracking. Conventional bitumen modification methods have been improving bitumen performance, but often rely on non-renewable or environmentally harmful additives. This study introduces a novel bio-nano ash (BNA) derived from coffee husk ash (CHA) and wood ash (WA) as a suitable bio-nanomaterial for bitumen modification, compared with mineral nano limestone (LS). The bio-nano ashes were prepared by controlled burning in a closed chamber to minimize CO 2 emission and secure eco-friendly synthesis. The 70/100 pen bitumen was modified with nanomaterials at 1.5%, 3.5%, and 5.5% by weight of bitumen. The additives were characterized using X-Ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer, Emmette, and Teller method (BET) analysis. Evaluating and modeling tensile metric performance, rheological properties and Bitumen-Fast-Characterization test (BFCT) using a dynamic shear rheometer (DSR) were evaluated. Results revealed that BNA significantly enhanced the tensile maximum force (F max ) and rutting resistance of modified bitumen compared with nano LS, due to increased complex shear modulus, elevated Equi-shear modulus temperature (T BTSV ) and reduced phase angle (δ BTSV ). At 5.5% WA, the maximum peak force and cumulative area were observed, indicating excellent energy absorption and the best overall mechanical performance of modified bitumen. The values of (R 2 = 0.999) from linear regression confirmed a strong, consistent link between mechanical and rheological parameters, evidencing bio-nano ash from bio-waste as a high-performance, eco-friendly bitumen modified supporting sustainable asphalt engineering.