The Effect of CR and SBS Modification on Permanent Deformation Properties of Asphalt Binder and Mixtures

This paper presents the results of a study on rutting resistance properties of Crumb Rubber (CR) modified asphalt mixtures in comparison with unmodified asphalt mixtures and Styrene Butadiene Styrene (SBS) modified asphalt mixtures. A total of six asphalt binder combinations were produced in laboratory, using identical base asphalt binder, the same SBS sources and five different CR contents. These five combinations, as well as the base asphalt binder, were tested using rotational viscosity (RV) and dynamic shear rheometer (DSR) to evaluate their viscosity and rutting properties at high temperatures. Hamburg wheel track rutting test was also performed on asphalt mixtures which were prepared by the same base asphalt, 5٪SBS modified asphalt and 16٪CR modified asphalt binders. The results showed that modifying the asphalt binder with Crumb Rubber and SBS, enhances rutting resistance properties of the asphalt mixtures; and that the rutting resistance of the asphalt mixtures containing 5٪SBS and 16٪CR modified asphalts, are almost similar and superior to that of the unmodified asphalt mixture. Moreover, the results of wheel track rutting test are in good agreement with the rheological properties of asphalt binders determined by DSR test.