Tannic acid-activated biochar enables dual environmental and durability enhancements in asphalt

Abstract

Asphalt fumes not only cause environmental pollution but also accelerate binder aging. In this study, tannic acid (TA) was employed to activate biochar, endowing it with dual functions in fume suppression and anti-aging. The TA-activated biochar (TB) possessed a more developed microporous structure, larger surface area, and abundant polyphenolic groups with free radical scavenging ability, resulting in enhanced adsorption and antioxidation capacity. Fume tests revealed that incorporating TB reduced the concentrations of VOCs and H₂S by 58.2% and 96.1%, respectively, while the ozone formation potential (OFP) and secondary organic aerosol potential (SOAP) decreased by 69.2% and 65.8%. After TFOT and UV aging, TB-modified asphalt exhibited excellent aging resistance, with more than a 50% reduction in softening-point increment and viscosity aging index, and ductility retention after aging was significantly improved. Improvements in rutting factor, low-temperature flexibility, and stress-relaxation capability further confirmed enhanced performance across the service temperature range. This work provides a sustainable approach to developing low-emission, aging-resistant asphalt pavements via enhanced adsorption-antiaging synergy in biochar.