Effects of Crumb Rubber and Carbon Black Obtained from Pyrolysis of Crumb Rubber on the Rheological Properties of Bituminous Binders

In this study, two different sizes (smaller and larger sizes of No.40 sieve) of crumb rubber (CR) and the carbon black, which was acquired as a result of the pyrolysis of crumb rubber, were employed in the bitumen modification with 3 different rates (5%, 10% and 15%). Penetration, softening point, rotational viscometer and dynamic shear rheometer (DSR) tests were carried out on both pure and modified binders. Additionally, penetration index (PI) values, which is an indicator of binders against thermal sensitivity, were determined. As a result of penetration, softening point and viscosity tests, it was observed that with the increase of CR used in the bitumen modification, the penetration values decreased, and softening points and viscosity values increased regularly. This condition indicates that the stiffness of the bitumen increases with CR utilization. In the evaluation of the sizes of CR, it was determined that the sizes of the materials had no considerable effect on these three tests. In the PI values, it was concluded that thermal sensitivities were lower compared to pure bitumen, except in the 5% CR with smaller sizes of No.40. As a result of the DSR test, it was concluded that with the increase of CR content, the parameters of binders in the resistance against rutting and their elasticity were increased. The utilization of carbon blacks, which obtained from the pyrolysis of CR, in the bitumen modification reduced the effectiveness of CR and especially the carbon black from smaller sizes of No.40 CR demonstrated no improvement in the properties of pure bitumen