Document Type : Original Article
Authors
1
Faculty of Engineering, Payam Noor University of Tehran
2
Assistant Professor, Transportation department, Faculty of Engineering, Payam Noor University of Tehran
3
Department of Civil Engineering, Iran University of Science and Technology, Tehran, Iran
Abstract
In this study, additive of waste polybutadiene rubber and Sasobit were used to increase bitumen performance. For this purpose, samples of bitumen 85/100 with 1, 2, 2.3, 3, 4, 5 and 6% polymer percentages (weight percentage of bitumen) and also 2.5% of Sasobit by using a high shear mixer were prepared. At first, classic bituminous tests (penetration degree, softness point, specific gravity, flash point, viscometer, and ductility) were carried out on bitumen. The preliminary results of the study showed that the waste PBR polymer reduces the degree of penetration and specific gravity and also increases the softness point and stiffens bitumen. In the ductility test, with increasing the amount of polymer, the elastic property decreases, and with percentages higher than 2.3 bitumen weight percent, the extensibility rate is less than 100. Therefore, 2.3% was selected as the optimum value of PBR polymer. Then, to evaluate the high temperature of bitumen, a dynamic shear rheometer (DSR) test was performed on modified bitumen samples. To evaluate the heat-treated bitumen modified with PBR, a thermal-gravimetrical analysis test (TGA) was performed and the results showed that the addition of PBR polymer increases thermal stability. The results also showed that adding waste PBR polymer to bitumen as well as in combination with Sasobit increased rutting resistance and generally improved the high temperature performance of bitumen. Accordingly, the mixture of 2.3%PBR and 2.3%PBR+2.5%Sasobit, respectively, increases the high temperature performance grade of bitumen, in one and two degrees. In the following, by the dynamic creep test and the effect of the wheel track at high temperature, the rutting resistance of asphalt mixtures samples were investigated and the results of this test showed that the resistivity of the produced sample 2.3% PBR + 2.5% Sasobit was significantly higher than other mixtures.
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