Rejuvenated Graphene Nanoplatelets Unlocking Extrinsic Self-Healing in Asphalt Binders

The aging and fatigue susceptibility of asphalt binders significantly reduce the pavement service life. This work presents a multifunctional strategy to enhance binder durability through the development of rejuvenated graphene nanoplatelets (GnP-Rej), where a vegetable-oil-based rejuvenator is intercalated within graphene nanoplatelets, enabling microwave-activated self-healing. Structural and thermal characterizations using Fourier Transformed Infrared spectroscopy (FTIR), Raman Spectroscopy (RS), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Thermogravimetric Analysis (TGA) confirmed successful rejuvenator's intercalation with the graphene nanoplatelets via noncovalent interactions. Additionally, rheological tests revealed that low-to-moderate neat GnP contents (0.1-0.18 wt %) improved rutting resistance (G*/sin(δ)), with microwave treatment further enhancing binder flexibility via improved rejuvenator diffusion. Fatigue testing using Linear Amplitude Sweep (LAS) method showed that microwave-activated rejuvenated graphene nanoplatelets (GnP-Rej_MW) formulations, particularly at 0.24 wt %, significantly extended fatigue life and reduced strain sensitivity (lowest B = 3.39), outperforming untreated counterparts. 2.2.3. Multiple Stress Creep Recovery (MSCR) results confirmed these findings, with 0.1-0.18 wt % GnP-Rej_MW binders demonstrating the best balance of deformation resistance (low Jnr) and elastic recovery (high R3.2%). Healing analysis revealed that microwave-activated binders with 0.18-0.24 wt % GnP-Rej achieved Healing Index (HI) above 1.4, confirming effective stiffness recovery and self-healing behavior. Overall, the combination of graphene nanoplatelets, biobased rejuvenator, and microwave activation provides a scalable route to smart, self-healing asphalt binders. These materials offer a promising solution for extending pavement lifespan while reducing maintenance frequency and cost.