Multi-Dimensional Performance Evaluation and Basalt Fiber Strengthening Effect of Secondary Hot In-Place Recycled Asphalt Mixtures

To address the rapid performance deterioration and secondary maintenance challenges of highway asphalt pavements that have undergone a first-round hot in-place recycling, this study investigates the feasibility of secondary recycling. Using the Yangzhou section of the G40 Expressway (Class II mild aging) and the Lianyungang section of the G30 Expressway (Class VI severe aging) as engineering backgrounds, three recycling schemes were designed and evaluated: Scheme A (100% RAP control), Scheme B (RAP with rejuvenator and virgin aggregate), and Scheme C (Scheme B reinforced with toughening basalt fibers). A comprehensive multi-dimensional testing protocol—including dynamic stability, semi-circular bending (SCB), low-temperature beam stripping, and Hamburg wheel-tracking—was employed to systematically evaluate the pavement performance of the second-time hot in-place recycled asphalt mixtures. The results indicate that while secondary recycled mixtures (Schemes A and B) maintain acceptable high-temperature stability, their intermediate-to-low temperature cracking resistance serves as the critical bottleneck, failing to meet standard specifications. In contrast, compared with Scheme A (100% RAP control), Scheme C (with basalt fibers) increased the flexibility index by 646.2–946.7%, the low-temperature fracture energy by 96.7–261.0%, and the Hamburg wheel-tracking stripping point by 48.1–62.2%, effectively mitigating the brittle fatigue common in aged recycled binders. According to the Jiangsu Expressway Maintenance Design Guidelines, the incorporation of basalt fibers elevated the comprehensive performance grade of the mixture from below Grade C to Grade A. This research provides a robust scientific basis and a “digital filter” for the large-scale engineering application of sustainable secondary recycling technology in heavy-traffic environments.