عنوان مقاله [English]
In this study, the waste polybutadiene rubber was used for the first time to improve the bitumen performance at intermediate and low temperatures. The 85/100 bitumen samples were prepared using a high-shear mixer with 1, 2, 2.3, 3, 4 and 5% polymer. The rotational viscometer, softening point, penetration and ductility tests were first performed on the polymeric bitumen. The initial results of the study showed that polybutadiene rubber increases the viscosity and softening point and increases the penetration index. In the ductility test, by increasing the amount of polymer, the cohision property of modified bitumen is decreased, and for the percentages greater than 2.3%, the ductility level is less than 100 cm. Therefore, the 2.3% level was selected as the maximum amount of polybutadiene rubber in the subsequent tests. Then, the dynamic shear rheometer test at the medium temperatures and the bending beam rheometer test at low temperatures were conducted on the modified bitumen sample for the 1, 2 and 2.3% polymer. The results of the study showed that this polymer improves the bitumen performance at the medium and low temperatures and can improve the low bitumen temperature up to 1°. In order to evaluate the role of this polymer in the asphalt mixture, the semi-circular bending test was performed at low temperature. The results of the asphalt mixture test showed that polybutadiene rubber at 2.3 wt% of bitumen increases the fracture toughness by 65% at -10 °C.