Thermodynamic and mechanical evaluation of moisture susceptibility in asphalt mixtures modified with aminated recycled PVC

Abstract The escalating accumulation of plastic waste, particularly polyvinyl chloride (PVC), necessitates sustainable recycling strategies in infrastructure engineering. This study investigates the chemical transformation of waste PVC into aminated recycled PVC (APVC) as a high-performance bitumen modifier to enhance the moisture stripping resistance of asphalt mixtures. APVC was synthesized through chemical amination and verified using FTIR. The research employed a multi-scale approach, integrating surface free energy (SFE) theory to characterize bitumen-water interactions with macro-scale mechanical testing, supported by aggregate surface analysis via the universal sorption device (USD). Results indicated that APVC modification significantly increased the total SFE of the bitumen, specifically boosting the basic component. This is attributed to the introduction of amine functional groups acting as Lewis bases, which establish strong chemical anchoring with the acidic silanol sites of granite. Thermodynamic analysis revealed that APVC was exceptionally effective in reducing debonding energy, with the granite-bitumen system surpassing the limestone system in thermodynamic resistance to debonding at a 6% dosage. Macroscopic evaluations via indirect tensile strength (ITS) tests confirmed these findings, with statistical validation via Tukey’s HSD test ( P < 0.05). The TSR of granite mixtures improved from 73.3% to 88.7%. A clear correlation was established between thermodynamic indices and mechanical performance. Ultimately, APVC serves as a potent anti-stripping agent that can potentially extend the service life of pavements by mitigating moisture-induced distresses like potholes in real-world conditions.