Multiscale Experimental Investigation on the Reinforcement Mechanism and Applications of Carbon Nanotube–Modified Asphalt

This study aims to elucidate the influence mechanisms of carbon nanotubes (CNTs) on asphalt binder and mixture performance through multiscale experimental characterization. Dynamic shear rheometry (DSR), multistress creep recovery (MSCR), single-edge notched beam (SENB) fracture testing, and atomic force microscopy (AFM) were employed to quantitatively correlate CNT concentrations with enhanced rheological properties and creep resistance. The recommended CNT dosage was determined based on homogeneous dispersion, performance improvement, and cost-effectiveness analysis. Subsequent evaluations focused on the high- and low-temperature stability, viscoelastic behavior, and fatigue resistance of CNT-modified asphalt mixtures at the identified recommended dosage. The results demonstrated the following: Microstructural analysis showed that CNT-induced wax crystallization and chemical interaction reorganized the colloidal structure of the asphalt. A 1.0% CNT dosage was identified as the recommended value to achieve uniform dispersion, performance gain, and cost-effectiveness. Validation tests on the mixture showed a 27% reduction in rutting depth, a 9.9% to 45.1% increase in dynamic modulus, and a 28% increase in flexural strength, confirming the cross-scale synergies from nanomodification to macroscopic performance. This research establishes a theoretical-experimental framework for designing nanoengineered asphalt materials, offering a viable solution for durable pavement infrastructure under extreme environmental and mechanical stress conditions.