OPTIMIZATION OF THE TEMPERATURE SUSCEPTIBILITY OF BITUMEN MODIFIED WITH WASTE TIRE RUBBER BY TAGUCHI METHOD

Abstract

The purpose of this study is to optimize the temperature susceptibility of the bitumen modified with the tire rubber. For this purpose, 2, 5 and 10 % waste tire rubber (by weight of bitumen) is mixed into 70-100 penetration bitumen at mixing temperatures of 150, 160 and 170oC for mixing time of 30, 60 and 120 minute and mixing speed of 250, 350 and 450 rpm. Taguchi method is used as design of experiment method. The temperature susceptibility of the binders is evaluated by the penetration index (PI). It is found that the order of the importance of variables affecting the temperature susceptibility of binders is tire rubber content, mixing speed, mixing temperature and mixing time, respectively. Optimum conditions for the maximum PI of 3.72 are obtained at the mixing temperature of 150oC, mixing time of 120 minute tire rubber content of 10% and mixing speed of 250 rpm. As a result, this new binder is produced by fewer experiments using Taguchi method compared to the other experimental methods. Thus, using the Taguchi method could save time and energy. Moreover, it is seen that tire rubber modified bituminous binders can provide better resistance against permanent deformations due to the lower temperature susceptibility in hot climate regions.