The effects of crumb waste tires on low temperature and elastic properties of bitumen and bituminous hot mixtures

In this study, performances of bitumen and asphalt mixtures modified by crumbrubber were compared to those modified by styrene-butadiene-styrene (SBS). The resultant mixtures were evaluated for their rheological and mechanical performances by different experimental techniques, such as rheological bitumen tests i.e., dynamic shear rheometer (DSR), bending beam rheometer (BBR), and hot mixture performance tests i.e., indirect tensile stiffness modulus, fatigue, semi-circular bending and toughness index. The experimental studies show that it is necessary to use two times more crumb rubber than SBS in order to reach the same performance attained by SBS. Crumb-rubber modification at high additive content exhibits higher elastic response, i.e., recoverable strain, than SBS modified mixture does. While the resistance to crack initiation of crumb-rubber modified mixtures increases with the increasing additive content, the resistance to the crack propagation decreases dramatically according to fatigue and semi-circular bending tests.Keywords: Crumb rubber, Styrene-butadiene-styrene, Rheological Properties, Performance Tests, Crack Propagation