Utilizing waste tire crumb rubber (CR) in asphalt modification is a promising method to enhance pavement performance while addressing the issue of waste tire disposal. Elevating CR content without compromising the pavement performance of asphalt is crucial for its practical and sustainable applications. However, conventional crumb-rubber-modified asphalt (CRMA) exhibits weakened physical and pavement properties when the CR content exceeds 25 wt%. Here, we propose a hybridization strategy combining CR and devulcanized CR (DCR) to produce high-performance modified asphalt with a total rubber content of up to 43 wt%. Modified asphalt containing 30 wt% CR and 13 wt% DCR (30CR-13DCRMA) demonstrates remarkable physical properties, with a softening point of 78.4 °C and a ductility of 15.33 cm. Rheology tests further reveal its superior rutting resistance (G*/sin δ), fatigue tolerance (G*·sin δ), and overall pavement performance compared to neat CR- or DCR-modified asphalt. Through rheological analysis, sol fraction measurement, gel permeation chromatography (GPC), and atomic force microscope (AFM) tests, it is revealed that the synergistic effect of CR and DCR can enhance the absorption capabilities of rubber particles, promoting their full swelling and resulting in a biphasic hard/soft microstructure within the asphalt matrix. This structural reorganization contributes to the outstanding comprehensive properties of this modified asphalt. This work establishes a hybrid-rubber asphalt system with high CR incorporation and well-balanced performance, offering a viable pathway toward sustainable pavement engineering.

Surfactants based on dynamic covalent bonds have attracted great interest in the past few decades due to the coexistence of covalent and non-covalent bonds. As a novel structure of surfactants, Gemini surfactants exhibit excellent surface activity and aggregation behavior. This work synthesized dicot quaternary ammonium salts containing aldehyde precursors, which can self-bind with primary amines of different chain lengths in water to undergo Schiff base reactions and generate pH responsive dynamic surfactants. Different linking groups and hydrophobic chain lengths were used to synthesize Gemini surfactants. The micelle aggregation behavior and surface activity of Gemini surfactants were systematically studied through surface tension, fluorescent probes, and conductivity. Particularly, the Gemini surfactant with 6 carbon atoms between amphiphilic groups and 10 carbon atoms in hydrophobic tail chain change the surface tension of water to 28.88mN·m⁻¹ with a critical micelle concentration of 0.117 mmol·L⁻¹.Products with different chain lengths and linking groups exhibit different micelle aggregation characteristics. Dynamic light scattering, rheology, and cryogenic transmission electron microscopy were used to study their high concentration aggregation behavior and the self-assembled vesicles and worm-like micelles of Gemini surfactants were revealed finally. The ability of micelles to encapsulate and release curcumin was studied by UV-visible spectroscopy and fluorescence spectroscopy, and it was found that they have excellent encapsulation ability for curcumin. Different from micelles, the aggregation behavior of Gemini surfactants changed with the concentration of them in aqueous solution increased.