Modern two-component modifiers inhibiting the aging process of road bitumen

Abstract

The bitumen physicochemical properties of are constantly changing during both the production of asphalt mixtures and the service of road pavements. These changes involve bitumen hardening which consequently cause formation of defects and cracks in road pavements. Therefore, in recent years, prolonging road pavement life by inhibiting the bitumen aging process is a key trend in road engineering, bringing many economic, environmental and social benefits. In line with these trends, the main objective of this research was inhibition of short-term bitumen aging by two-component chitosan-based polymer composites containing ligands with different chemical structures, i.e. polyaniline, methacrylamide and 2-acrylamido-2-methylpropanesulfonic acid. This paper presents their effect on the TFOT aging process, as well as physicochemical and structural changes. Studies show that the strongest anti-aging properties are demonstrated by the chitosan:polyaniline composite. Its use at 2 % w/w allows it to maintain 90 % of the primary penetration value, increase the softening point by only 2°C and increase dynamic viscosity by 17% in comparison to non-aged modified bitumen. In addition, the use of the composite makes it possible to reduce the degree of bitumen components oxidation, which is seen from the reduction of carbonyl and sulfoxide indices by more than 33 % and 47 %, respectively.