Synergistic Effect of Nanosilica on Rutting and Cracking Resistance in Polymer-Modified Asphalts

Abstract: In many regions worldwide, modified binders have become the standard for enhancing pavement performance. To address the limitations of polymer-modified asphalts, nanomaterials such as nanosilica have been widely adopted as asphalt binder modifiers. This study explores the synergistic effects of nanosilica particles in improving the performance of various polymer-modified asphalts. Two polymers—polyethylene and polypropylene—were incorporated into the asphalt binder at varying concentrations. Fourier-transform infrared (FTIR) spectroscopy was used to investigate the chemical interactions between the nanosilica and polymer-modified binders. Performance properties, including fatigue life at different temperatures and resistance to rutting deformation, were evaluated. Response Surface Methodology (RSM), based on a Central Composite Design, was utilized to develop performance predictive models and optimize the overall asphalt mixture. Additionally, the reliability of the nano-modified polymer asphalt binders was assessed using parametric survival analysis. The results revealed a significant improvement in fatigue life for nano-modified polymer asphalts compared to control mixtures, indicating greater resistance to fatigue cracking under high-stress conditions. Rutting deformation was reduced by nearly 50% in nano-modified mixtures compared to standard polymer-modified asphalts. Moreover, polypropylene-based nano-modified asphalts demonstrated superior rutting resistance compared to their polyethylene counterparts, highlighting polypropylene’s greater ability to enhance mixture stiffness. Reliability analysis further confirmed that polypropylene nano-modified asphalts outperformed polyethylene nano-modified asphalts at all strain levels. The validation of the RSM model showed a strong correlation between predicted and experimental results, with prediction errors under 7%, demonstrating the model's robustness.