Rheological properties of styrene butadiene rubber modified bitumen binder

Abstract

The study investigates the rheological properties of bitumen of 60-70 penetration grade modified with Styrene Butadiene Rubber (SBR). SBR is an elastomer which is an important sort of synthetic rubber. It is a copolymer whose molecular structure primarily consists of organic compound styrene and butadiene chain. Bitumen is visco-elastic in nature. The rate of load application and temperature has a great influence on its performance. Various fundamental properties of bitumen were evaluated, namely complex shear modulus (G*), short-term ageing, long-term ageing, viscosity, penetration and softening point by using Dynamic Shear Rheometer (DSR), Rolling Thin Film Oven Test (RTFOT), Pressure Aging Vessel (PAV), Rotational Viscometer (RV), Penetrometer and Ring and Ball Test, respectively. The binders were mixed with varying percentage of SBR i.e. 0, 1, 2, 3, 4, and 5% by the weight of bitumen binder. The use of SBR has played an active role in improving the viscoelastic properties of bitumen. The use of SBR modifier changes the rheological behavior of bitumen by increasing its complex shear modulus (G*) and the resistance of mixture against permanent deformation (rutting). It was also found that increasing the content of SBR led to the increase in viscosity of modified bitumen, which helps in elevating the mixing and compaction temperature of asphalt mixtures.