Phase separation and thermal degradation of plastic bag waste modified bitumen during high temperature storage

Abstract

Phase separation and thermal-oxidative degradation can occur during storage and transportation of polymer modified bitumens (PmB), and both phenomena may substantially erode the properties of the PmB. In this paper, we investigate the phase separation and thermal degradation issues of waste plastic bag modified bitumen (WPmB) samples stored under quiescent conditions, as suggested by the standard storage stability testing procedures, and under a low continuous agitation. As for the phase separation, empirical basic tests, dynamic rheological tests and dissolution in a diluent of a small quantity taken from each section; top, intermediate and bottom, of the WPmB stored samples are used to evaluate the potential of segregation and migration of plastic particles within the stored samples under static and agitation conditions. As for the WPmB degradation, FTIR spectra analysis and different binder ageing testings were used to estimate the effect of both heat and air on the properties of the WPmB during its storage at high temperature for a duration of 48 h. The phase separation results demonstrated that the totality of the plastic particles have separated completely from the bitumen during static storage. However the plastic remains well distributed in the bituminous matrix of the agitated samples thanks to the low continuous agitation, which obviously manage to prevent plastic particles from flocculating and then from separating. Moreover, the thermal degradation results indicate that no considerable adverse effects of the high temperature storage are observed on the ageing of the modified bitumen as well as on the thermal degradation of the waste plastic bag additive.