Recycle of waste tire rubber powder in a novel asphalt rubber pellets for asphalt performance enhancement

Abstract

Asphalt rubber has been considered as an ideal road construction material due to its excellent rutting resistance, fatigue performance, crack resistance, and noise reduction functions. However, the preparation of asphalt rubber requires special equipment and takes higher cost. In this paper, a kind of asphalt rubber modifier pellets (ARP) that can be directly injected was prepared using a screw extruder, so as to simplify the production process and reduce equipment energy consumption during the synthesis of asphalt rubber. Industrial modifier PelletPAVE as control group, firstly, scanning electron microscopy (SEM) was employed to examine the internal microstructure of the two types of modifier pellets, and the storability were further evaluated. The rotational viscosity, High and low temperature rheological behaviors and fatigue properties of asphalt with two modifier pellets were investigated by rotational viscometer, dynamic shear rheometer (DSR), and bending beam rheometer (BBR), respectively. Finally, Infrared spectroscopy was used to explore the mechanism of modification. The findings revealed that 50% crumb rubber, 40% asphalt, and 10% calcium hydroxide are the optimal material compositions for preparing asphalt rubber pellets. The modifier particles coated with anti-sticking agent can achieve the same storability as PelletPAVE. The viscosity of the modifier pellets modified asphalt prepared is marginally higher than that of the PelletPAVE modified asphalt. Incorporating modifier pellets to asphalt demonstrates superior fatigue and crack resistance than PelletPAVE, as well as lower high temperature performance. Action mechanism of modified asphalt with both types of modifier pellets is regarded as a physical process. The asphalt rubber pellets prepared in this study reveal the merits of easy transportation, convenient direct injection, and wide application field.