Activation preparation of waste tire pyrolytic carbon black and its reinforcing application in modified asphalt

Abstract

Pyrolytic carbon black (PCB) has been shown to improve the performance of asphalt, but its use in modified asphalt often results in poor low-temperature behavior, fatigue resistance, and compatibility. This study explores four activation strategies (HCl, KOH, steam, CO₂) to enhance the performance of PCB-modified asphalt. PCB's physical and chemical properties were characterized by ash content measurements, scanning electron microscopy (SEM), and nitrogen adsorption. Among these, HCl activation enhanced compatibility, low-temperature crack resistance, and fatigue resistance of PCB-modified asphalt. KPCB-A demonstrated a 3.1°C improvement in high-temperature failure temperature compared to PCB-A. Steam activation maximized fatigue resistance (196 million cycles at 1 % strain) through mesopore-dominated structures. CO₂ activation, which does not alter PCB's chemical properties, yields similar performance to HCl activation. Fluorescence microscopy (FM) and image analysis revealed that the increased specific surface area of activated PCB correlated with improved asphalt compatibility. The increased pore volume enhanced PCB's adsorption potential, and chemical activation (compared to physical activation) further enhanced the adsorption of light components. This study quantified the performance trade-offs of different activation methods, revealed the linkage between PCB pore structure and the performance of modified asphalt, and advanced the sustainable reuse of PCB in asphalt pavements.