Document Type : Research Article
School of Civil Engineering, Iran University of Science and Technology (IUST).
School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran
The use of crumb rubber to modify the binders has been the interest of researchers for many years. It has been proven that the use of asphalt mixtures containing crumb rubber is leading to improve performance and increase durability of asphalt pavement. However, increasing the viscosity of crumb rubber modified (CRM) binder which increases mixing and compaction temperature of asphalt mixture, is known as one of the disadvantages of using crumb rubber. So, there is a good concept for using warm mix additives to besides improving the performance of asphalt mixture, reduce energy consumption and environmental pollution also be considered. On the other hand, the binder has an important role in the investigation of the performance of the asphalt mixture. It is also time-consuming and costly to evaluate the properties of asphalt mixtures. Hence, evaluating the performance characteristics of the binder helps in understanding the performance of asphalt mixtures against various types of damage. The main objective of this study is to investigate the effect of organic warm mix additives (waxes) on the rutting performance of CRM binders by using the multiple creep stress recovery (MSCR) test. It was found that the MSCR test results have a good correlation to rutting than SHRP criteria. The results of this study showed that the use of polypropylene wax in addition to increasing rutting resistance of CRM binder also will lead to an increase in pavement traffic level by one degree. Despite this, slack wax reduced the rutting resistance of the CRM binder by increasing the Jnr parameter.