Rheological and chemical characterization of plasma-treated rubberized asphalt using customized extraction method

Abstract

The storage instability issue of rubberized asphalt caused by the inherent incompatibility significantly affects its engineering performances. In this study, cold plasma was utilized to activate the inert surface of Crumb Rubber (CR) particles to further improve the compatibility in rubberized binder. Using a customized extraction method and a developed model, the mechanism of Cold Plasma Effect (CPE) was investigated by rheological and chemical methods, respectively. In terms of the rheological characterization by Dynamic Shear Rheometer (DSR) testing, the CPE on rheology was identified as the primary Particle Effect (PE) and the secondary Interaction Effect (IE). In addition, CPE together with its PE and IE portion constantly increased with an increase in CR content, while no significant tendency was found with the varying size. With respect to the chemical characterization by Gel Permeation Chromatography (GPC) testing, the results indicated the cold plasma treatment significantly resulted in an increase in the Large Molecular Size (LMS) fraction of binder, and this effect was more evident as the CR content increased and the size reduced. However, the Fourier Transform Infrared Spectroscopy (FTIR) testing failed to characterize the effect of cold plasma treatment. Furthermore, the statistical analyses reported a strong correlation between the above corresponding changes in rheology and chemistry. Above all, the mechanism of CPE on binder properties could thus primarily be seen as the promotion in diffusion of lighter fractions of asphalt binder into the plasma-treated CR particles.