Rheological, healing and microstructural properties of unmodified and crumb rubber modified asphalt incorporated with graphene/carbon black composite.

• GC was synthesized by the ball milling method and employed for asphalt modification. • GC improved the mechanical properties and rutting resistance of asphalt binders. • GC promoted the thermal-activated healing potential of the two asphalt binders. • GC uniformly dispersed in asphalt binders by physical and chemical reactions. Graphene, featuring excellent mechanical, electrical, thermal, and optical properties, has received increasing attention in asphalt modification. However, high production costs and poor dispersibility used in asphalt binders have limited its large-scale application. Therefore, in the present work, a high-quality and inexpensive carbon black, a typical carbon-based material and tire processing by-product, was selected to compound graphene to improve its dispersion in the base and crumb rubber (CR) modified asphalt matrix well as reducing the cost of utilization. This modifier is ultimately expected to enhance the performances of both the base and CR modified asphalt. First, the graphene/carbon black composite (GC) was prepared by the ball milling method and used to modify the asphalt binders. Then, the dynamic viscoelastic mechanical tests, i.e., multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), and fatigue-healing cycle test, have been conducted to comprehensively evaluate the rheological and healing properties of the base and crumb rubber (CR) modified asphalt binder. Subsequently, scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy were adopted to reveal the morphology and interaction between GC and asphalt binders. The test results indicated that the incorporation of GC significantly improved the high-temperature rutting resistance and heat-activated healing performance of the two asphalt binders. Moreover, the introduction of GC enhanced the fatigue damage tolerance and low-temperature ductility of the CR modified asphalt. Meanwhile, the loose GC interacted with the asphalt molecules to form tight connections through physical and chemical reactions. This may cast some light on the application of GC in asphalt modification. [ABSTRACT FROM AUTHOR]