Study and Comparison between Effect of SBR\PS Blend and SBS on Asphalt Mixtures Fatigue Failure

Road safety and convenience of driving has been greatly affected by pavement quality; so, it is essential to evaluate the asphalt performance and its common failure such as Fatigue. Nowadays, an increase in frequency of heavy load traffic causes premature fatigue distresses in asphalt pavements which leads to enhancement the costs of road maintenance and repairs. This makes the improvement of the properties of bitumen and asphalt mixtures inevitable. Although the amount of bitumen in asphalt mixtures is not high, it has a significant impact on mixture performance. Styrene-butadiene-styrene is known as one of the most used polymers to improve the properties of asphalt which has led researchers to use alternative materials with the same functional properties due to the lack of sufficient instability in bitumen and its high price. In this study, to find a suitable alternative for this polymer, a mixture of low-cost polymers of styrene-butadiene-rubber and polystyrene has been used with the ratio from 35 to 65 percentage of each combination. In this regard, styrene-butadiene-styrene and polymer blends has been added to the bitumen of the asphalt samples by 3 to 5 percentage. Moreover, 2 percent nanoclay has been mixed inorder to increase the stability of the polymers in bitumen. Thereafter, four-point bending beam and indirect stretch tests has been utilized to evaluate fatigue performance of samples. The results of this research shows that the polymer blends with mentioned composition can be used instead of unstable and expensive traditional SBS, especially when samples have more than 50 percentage styrene-butadiene-rubber in their compositions.