Asphalt modification using a novel bio-based amido-boron additive synthesized from waste tallow

In this study, a novel and chemically engineered asphalt binder additive (AFBN) was developed through a multistep synthesis route incorporating waste tallow, 1,6-diaminohexane, and hexagonal boron nitride (h-BN). The originality of the additive lies in its dual-function molecular structure, comprising amide linkages and nitrogen sites capable of electrostatic interaction with boron species, designed to mimic and enhance the viscoelastic network of bituminous systems. The structural integrity and successful functionalization of the synthesized additive were confirmed through comprehensive spectroscopic techniques, including FTIR, 1 H-NMR (with D₂O exchange and TFA protonation), and 13 C-NMR, while thermogravimetric analysis (TGA) verified its thermal stability under asphalt modification conditions. The additive was incorporated into asphalt binders at varying ratios (1%, 2%, 4%, 6%) and evaluated via conventional binder tests, Brookfield rotational viscosity, and Dynamic Shear Rheometer (DSR) tests, both before and after Rolling Thin Film Oven Test (RTFOT) aging. The 2% AFBN-modified binder demonstrated superior rutting resistance and enhanced elastic behavior, as evidenced by increased G * /sin δ and reduced phase angle values. A multi-objective optimization study based on Response Surface Methodology (RSM) revealed that while 2% AFBN appeared optimal experimentally, a numerically optimized dose of 1.49% at 70 °C achieved a G /sin δ of 1374.19 Pa with a desirability score of 1.0, indicating maximum rheological efficiency with reduced material input. This data-driven approach highlights the capability of statistical modeling to refine binder formulation beyond conventional trial-and-error methods.