Performance characteristics of modified bitumen with respect to its physical and rheological properties

Bitumen is a complex polymeric mixture of hydrocarbon molecules and some functional groups. There are chemical changes occurring when bitumen is modified with a polymer or even during ageing. In order to enhance the performance and service properties of bitumen, polymers are added. Polymer Modified Bitumen (PMB) are used extensively in asphalt surfacing and seals. PMB has to characterised differently from viscosity grade bitumen and the improved performance properties are difficult to demonstrate with convention empirical rheological tests. The challenge in physical property characterization is to develop physical tests that can satisfactorily characterize key asphalt binder parameters and how these parameters change throughout the life of an HMA pavement. In India, the methods for rheological characterization of bituminous binders are inadequate to characterize the bitumen. Hence a complete rheological study and charaterization of bitumen using dynamic shear rheometer would be helpful. The changes in physical and rheological properties by the addition of Ethylene Vinyl Acetate (EVA), a plastomer, Linear Butadiene Styrene (SBS), an elastomer and Crumb Rubber (CR) are discussed in the paper to some extent.