Determination of rheological properties of modified asphalt binder incorporating with sasobit additive

Abstract

This study investigates the rheological properties of bitumen (asphalt) binder penetration grade 80-100 and 60-70 modified with an additive Sasobit wax. This additive is a Long-Chain Aliphatic Hydrocarbon (LCAH). It is obtained from coal gasification using the Fischer-Tropsch process. Bitumen is visco-elastic material where temperature and rate of load application have a great influence on their performance. The properties evaluated include the rheological properties of the modified bitumen binder. These properties were complex shear modulus G* using Dynamic Shear Rheometer (DSR), short term aging by Rolling Thin Film Oven Test (RTFOT), long term aging by Pressure Aging Vessel (PAV), viscosity by Rotational Viscometer (RV), penetration by Penetro meter and softening point by Ring and Ball test. Results obtained from the study indicated the effect of Sasobit on the binder, and also depends on the quantity (%) of the additive used and test temperature. The binders were mixed with various percentages of the Sasobit wax at the 1, 2, 3, 4 and 5% by weight of bitumen binder. Using the Sasobit showed prominent results in improving the viscoelastic properties of ordinary bitumen. The effects Sasobit modifiers influenced significantly the rheological behaviour of bitumen by increasing its complex shear modulus (G*) and increasing the resistance of mixture against permanent deformation (Rutting). Despite the advantages of FT-paraffin on bitumen performance at high temperatures, it does not show a considerable influence on the intermediate temperature performance of bitumen. In addition, results show that increasing the additive content lowers the viscosity of modified bitumen. This in return can reduce the mixing and compaction temperature of asphalt mixtures