The Combined Effect of SBS and Proplast in Improving the Stone Mastic Asphalt Performance

In this study, the role of both SBS and Proplast fiber additives in improving the performance of SMA in confronting the rutting phenomenon has been investigated. Using Stone Mastic asphalt mixtures can play a considerable role in reducing persistent and plastic deformation caused by rutting. To perform the experiments, 84 Marshall samples and 8 samples in the slab form were prepared in 4 types. In order to determine the optimum asphalt content, the Marshall design method was used and additives, with extensive studies in the literature, were selected as 5% SBS and 0.6% Proplast fibers. Then marshall stability to flow ratio, bitumin draindown from the mix and determining rutting percentage using French method ,tests were conducted and then these materials were added to the stone mastic asphalt mix, individually and simultaneously. The results showed that samples containing SBS only or containing both SBS and Proplast fibers simultaneously, has better endurance comparing to samples without additives. They showed an increase of about 10 percent in endurance and also the lowest rutting percentages among all the samples as well, while samples without additives showed the highest rutting percentage among all the samples. Regarding to the results of the experiments, using SBS and Proplast fibers simultaneously leads to a reduction in rutting percentage to around half, comparing to samples without additives. Finally, based on the results of this study it can be concluded that the use of both SBS and Proplast fibers in the SMA, can not only improve the physical characteristics of this type of asphalt, but also can have a significant role in dealing with the rutting phenomenon and so can be considered as a good choice for hot areas with heavy traffic loads