Surface modification of ground tire rubber particles by cold plasma to improve compatibility in rubberised asphalt

Abstract

The inert surface of Ground Tire Rubber (GTR) particles results in its weak compatibility with asphalt matrix and thus causes serious phase separation in rubberised asphalt. Meanwhile, plasma treatment is able to modify the polymer surface effectively. This study applied cold plasma to modify the surface of GTR particles for compatibility improvement in rubberised asphalt. The surface characteristics of plasma-treated GTR particles with varying treatment power and time were investigated, by means of water contact angle metre, X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscope (SEM), respectively. The results reported the enhanced surface hydrophilicity, lipophilicity, and roughness as well as the incorporation of oxygen-containing functional groups of GTR particles after plasma treatment. The optimal processing parameters were determined as the discharge power of 250 W and the processing time of 8 min. The GTR-asphalt compability after the most effective plasma treatment was evaluated by measuring the storage stability and rotational viscosity of rubberised binder. Regardless of base asphalt source, GTR particle size and dosage, cold plasma treatment truly enhanced the compatibility. Furthermore, the increased dosage from 10% to 20% and the decreased size from 30 to 80 mesh generally had a growing positive effect on compatibility.