Morphology and image analysis of polymer modified bitumens

This paper presents a laboratory study of styrene butadiene styrene (SBS); ethylene vinyl acetate (EVA) and ethylene butyl acrylate (EBA) based polymer modified bitumen samples (PMBs). The PMBs have been produced by mixing a 50/70 penetration grade unmodified (base) bitumen with copolymers at different proportions. The fundamental characteristics of the PMBs have been determined using conventional methods. The morphology of the samples as well as the percent area distribution of polymers throughout the base bitumen have been characterized and determined by means of fluorescent light optic microscopy and Qwin-Plus image analysis software, respectively. The results indicate that the fundamental properties and morphology of the modified bitumens are dependent on the type of polymer and polymer content. Polymer modification improves the conventional properties of the base bitumen such as penetration, softening point, temperature susceptibility. At low polymer contents, the samples reveal the existence of dispersed polymer particles in a continuous bitumen phase, whereas at high polymer contents a continuous polymer phase is observed. Moreover it is found out that a relationship exists between the polymer content and percent area distribution of polymers. (C) 2008 Elsevier Ltd. All rights reserved.