Effect of aging levels and induction factors on self-healing ability by induction heating method in hot asphalt mixtures

Asphalt aging severely degrades pavement performance, necessitating efficient self-healing technologies. The self-healing mechanism was evaluated using induction heating facilitated by scrap iron powder as the inductive agent, incorporated into the filler. The study assesses the combined influence of four critical factors: aging levels (Short-Term/Long-Term), inductive agent dosage (30 % and 70 % of filler volume), inductive agent particle size (46 μm and 63μm), and testing temperature (5 °C and 25 °C). Samples were prepared with silica materials and AC 70–60 bitumen. Healing potential was quantified using the Semicircular Bending (SCB) test. The inductive agent was analyzed using X-ray Fluorescence)XRF( and binder chemical changes were evaluated using Fourier-Transform Infrared Spectroscopy (FTIR). To statistically isolate the effect of each factor on the self-healing capability, a Factorial Analysis of Variance (ANOVA) was employed. The ANOVA results conclusively identified Aging as the most statistically significant factor (p < 0.001), leading to a sharp decline in the Healing Index (e.g., from 56 % STA to 42 % LTA at 25 °C). This performance reduction was chemically substantiated by FTIR analysis, which showed an increase in harmful aging-related functional groups (Carbonyl and Sulfoxide). Conversely, the Inductive Agent dosage showed a significant positive effect (p = 0.040), as higher concentrations increased the induced temperature (up to 81.5 °C) and impr°ved Healing efficiency. Under optimal conditions, samples achieved 100 % recovery of fracture toughness, validating the method's full potential. Ultimately, this study provides a validated statistical and chemical framework, demonstrating that optimized induction heating achieves a 100 % restoration of fracture toughness, marking a significant stride towards economically viable and sustainable self-healing pavement solutions. • ANOVA: Aging is the most dominant factor affecting the Healing Index (HI). • 100 % HI achieved in Short-Term Aged samples with 70 % scrap iron powder dosage. • The 70 % scrap iron powder dosage (inductive agent) has a significant positive effect on HI. • HI reduction in Long-Term Aged samples is due to severe capillary flow restriction. • FTIR analysis: Increased carbonyl/sulfoxide groups impaired binder repairability.