Introduction: Asphalt binders exhibit strong viscoelastic behavior at intermediate temperatures (15-35°C), where rutting is no longer the dominant pavement distress. Instead, repeated traffic loading leads to fatigue cracking that progressively reduces pavement performance. Such cracks typically initiate within the bitumen mastic or at the bitumen–aggregate interface, indicating that mixture fatigue behavior is largely controlled by binder properties. Therefore, understanding binder fatigue characteristics is essential for evaluating asphalt mixture durability. Appropriate material selection and binder modification strategies are crucial for evaluating asphalt mixture durability in pavements. Methods: Utilizing Linear Amplitude Sweep (LAS) and Time Sweep (TS) tests, the damage characteristic relationships for modified asphalt with varying Cu2O dosages under multiple aging conditions were determined. This revealed the influence of modifier content on material stiffness and damage mechanics. The dynamic mechanical behavior within the Linear Viscoelastic (LVE) region was comprehensively characterized using dynamic modulus and phase angle master curves. Results: Fatigue resistance exhibited a non-monotonic trend with increasing nanoparticle content, reaching an optimum at 3% concentration, where peak fatigue life was achieved. Performance degradation beyond this threshold is postulated to result from reduced effective reactive surface area due to nanoparticle agglomeration. Discussion: Nano-Cu2O agglomeration at higher dosages limits modification efficacy, highlighting the need for optimized dispersion techniques. The study did not investigate the chemical reaction mechanisms between nano-Cu2O and asphalt or their long-term fatigue effects, introducing uncertainty regarding field performance. Conclusion: Nano-Cu2O significantly improved binder fatigue life under both unaged and aged conditions, with optimal performance at 3% dosage, producing a 16.8% increase. Higher contents caused particle agglomeration and reduced interfacial stability. LAS results indicated broader stress peaks and higher yield.
Yang et al. (Wed,) studied this question.