Green synthesis of a broad-spectrum UV-blocking bitumen modifier: Investigation of anti-aging performance and mechanism in bitumen

The popularization of inorganic nanomaterials doping, which serves as an effective method to improve the aging resistance of bitumen, is constrained by suboptimal lipophilicity and limited broad-spectrum UV absorption. To overcome this, we synthesized an environmentally-friendly, broad-spectrum UV-blocking nanocomposite by coating nano TiO2–ZnO (Nano-TZ) with sustainable lignin. TEM, T-IR, and photocatalytic activity test results indicate successful lignin coating on the Nano-TZ surface, with the optimal concentration being 15% (Nano-15L@TZ). Rheological test results demonstrated improved UV- and thermal-oxidative aging resistance of the Nano-15L@TZ-modified bitumen compared to those treated with uncoated nanomaterials. The synergistic modification mechanism of the Nano-15L@TZ composite was elucidated by combining the contact angle with UV–Vis and XPS VB tests. Nano-TZ exhibited broad-spectrum UV blocking properties that mitigated the UV aging of bitumen and lignin, while lignin effectively improved its compatibility with bitumen and captured radicals generated by Nano-TZ and aged bitumen.