Quantitative evaluation of microscale frictional stability in modified asphalts: Insights from chaos dynamics and time-series analysis

While asphalt friction critically impacts road safety, existing studies predominantly focus on macroscale properties, leaving microscale dynamic stability mechanisms underexplored. A novel chaos dynamics-based framework integrating AFM friction tests, time-series analysis, and the maximum Lyapunov exponents (MLE) were developed to quantify the stability of modified asphalts in the current work. Four types of asphalt: base asphalt, SBS-modified asphalt (SBS-MA), organic montmorillonite-modified asphalt (OMMT-MA), and titanium dioxide-modified asphalt (TiO 2 -MA), were prepared and subjected to rolling thin film oven (RTFO) aging. The experimental results revealed that microscale surface morphology, stick–slip behavior, and dynamic friction stability are significantly influenced by the type and dispersion of modifiers. TiO 2 -MA exhibited the smallest friction force fluctuation, lowest pile-up volume, and lowest MLE, indicating the highest dynamic stability. In contrast, OMMT-MA showed weak shear resistance and chaotic frictional behavior due to uneven modifier dispersion. The proposed framework offers a new quantitative approach to characterize and differentiate the frictional performance of modified asphalts, providing mechanistic insights for optimizing asphalt design under dynamic loading conditions.