Evaluation of the properties and microstructure of plastomeric polymer modified bitumens

This paper presents a laboratory study of modified bitumen containing plastomeric polymers; Evatane® 2805, Elvaloy® 3427, and Elvaloy® 4170. A 50/70 penetration grade base bitumen has been mixed with plastomeric polymers at different proportions by means of a high shear laboratory type mixer. The properties and microstructure of the samples have been determined and characterized using conventional and empirical test methods and fluorescence microscopy respectively. Qwin Plus image analysis has also been investigated in order to determine the % area distribution of plastomeric polymers throughout the base bitumen. The results indicated that polymer modification improved the conventional properties of the base bitumen such as; penetration, softening point, temperature susceptibility, etc. The microstructure and properties of the polymer modified bitumens are dependent on the type of polymer, the solubility of polymer in bitumens and polymer content. At low polymer contents, the samples revealed the existence of dispersed polymer particles in a continuous bitumen phase, whereas at high polymer contents a continuous polymer phase has been observed for the Evatane® 2805 and Elvaloy® 3427 polymers. Among the plastomeric polymers no significant polymer phase has been observed for the reactive terpolymer Elvaloy® 4170 although its conventional properties have been improved. It is also found out that a relationship exists between the polymer content and percent area distribution of polymers except for reactive terpolymer.