Multi-scale fatigue evaluation and thermodynamic bonding characterisation of asphalt binders and mixtures modified with aminated recycled PVC

The escalating plastic waste necessitates sustainable upcycling in the pavement industry. This study investigates the multi-scale fatigue performance and thermodynamic bonding of asphalt binders and mixtures modified with aminated recycled PVC (APVC). After chemical functionalisation of PVC was verified by FTIR, binders (2%, 4% and 6% APVC) were evaluated using surface free energy (SFE) theory and linear amplitude sweep (LAS) tests. Macroscopic fatigue was assessed via indirect tensile fatigue (ITF) testing. Results showed that APVC increased total surface free energy and the work of adhesion/cohesion. LAS analysis revealed that 6% APVC optimised fatigue capacity and mitigated damage. Consequently, 6% APVC-modified mixtures exhibited up to a 308% increase in fatigue life at 20 °C. High logarithmic correlations (R2 > 0.970) between SFE parameters and fatigue life identify the work of cohesion as a key thermodynamic indicator, suggesting APVC as a viable pathway for resilient road infrastructures.