Characteristics of elastomeric and plastomeric binders in contact with natural asphalts

Bituminous binders are known to have simple rheological properties. Natural asphalts, such as Trinidad Lake Asphalt (TLA) and Uintaite, are often used for bitumen modification in order to obtain improved performance of the respective asphalt mixture (such as stiffness and deformation resistance). This paper presents the results from a series of assessments of ‘empirical’ and rheological properties of bituminous binders, which incorporate natural asphalts (specifically TLA and Uintaite) and/or polymer modifiers. Binder ‘empirical’ properties, measured by penetration and Ring and Ball softening point tests, showed that natural asphalts reduce or increase these respective “empirical” values at the level anticipated by “conventional blending formulas”. However, rheological analysis showed that the “stiffening” effect caused by addition of natural asphalts, which is normally anticipated in the case of asphalt incorporating unmodified bitumen, took place in a different way if a polymer modifier was also used.