Changes of Properties of Bitumen Binders by Additives Application

Abstract

Requirements for properties of bituminous binders are determined in the European standards. The physico-chemical behaviour of bitumen depends on its colloidal structure (asphaltenes dispersed into an oily matrix constituted by saturates, aromatics and resins) that depends primarily on its crude source and processing. Bitumen properties are evaluated by group composition, elementary analysis, but more often conventional or functional tests. Bitumen for road uses is assessed according to the physical characteristics. For the purpose of improving the qualitative properties of bitumen and asphalts the additives are applied e.g. to increase elasticity, improving the heat stability, improving adhesion to aggregate, to decrease viscosity, increasing the resistance to aging, to prevent binder drainage from the aggregate surface, etc. The objective of presented paper is to assess and compare effect of additives on properties of bitumen binders. In paper, the results of bitumen properties, penetration, softening point, and dynamic viscosity of two paving grade bitumen 35/50, 50/70 and polymer modified bitumen PmB 45/80-75 are analyzed and also the changes of these properties by the application of selected additives (Sasobit, Licomont BS100, Wetfix BE and CWM) to improve adhesion to aggregate and improve workability. Measurements of properties have been performed according to the relevant European standards. The laboratory tests showed significantly increasing the softening point of paving grade bitumen 50/70 and 35/50 by 13 to 45°C. The effect of various additives on bitumen softening point is different. Penetration varies according to type of bitumen and type of used additive. The penetration values of modified bitumen PmB 45/80-75 with additives Sasobit and Licomont BS100 show increase of bitumen stiffness of 16 0.1mm and a shift in the gradation. The changes in penetration and in softening point significantly shown when calculating on Penetration index as a parameter of temperature susceptibility. The additives changed the viscosity of bitumen to lower values mostly with modified bitumen. In case of the additive Wetfix BE mix in 35/50caused the viscosity increase. The additive changes the properties of original bituminous binders, and that can affect the properties of asphalt mixtures and asphalt layers.