Optimizing the formulation design and investigating the composite modification mechanism of pyrolysis carbon Black/Polyethylene/Synthetic plant ester composite modified asphalt

Pyrolysis carbon black (PCB) is the surplus product of waste tires after pyrolysis. Polyethylene (PE) is the main component of disposable plastic bags, and synthetic plant ester (SPE) is an environmentally friendly plasticizer that has recently emerged. In this study, the aforementioned three materials were used to prepare an environmentally friendly composite-modified asphalt (CM-A). The optimization of the formulation design of the PCB/ PE/SPE additive with asphalt was performed using the response surface mixture-design method, with conventional asphalt performance as the control index. The compound modification mechanism was investigated using modern microscopic testing techniques. The recommended formulations for the additives were BA:PCB:PE:SPE = 0.881:0.081:0.022:0.016 by mass. The resulting CM-A exhibited comparable penetration, ductility, and fatigue properties to base asphalt (BA), with higher high-temperature rutting resistance and softening point values. Microscopic test results revealed that the PCB/PE/SPE was physically blended with asphalt. The plasticizing effect of SPE enhanced the plasticity of PE molecules and significantly improved the compatibility properties of PE and BA. The thermal behavior of CM-A was similar to that of BA but with a slightly higher ash content due to the presence of PCB. The results provide a reference for the industrial production of asphalt modifiers, modification mechanism studies, and a new solution to alleviate environmental pollution and resource waste problems from solid waste accumulation.