Mix Design and Performance of Crumb Rubber Modified Asphalt SMA

摘要

The scrap tire crumb rubber modified (CRM) bitumen mixture with over 20% crumb has higher viscosity, better flexibility, improved anti-fatigue and anti-aging properties. This paper mainly investigated material design and performance of asphalt rubber stone mastic mix (AR-SMA). The rotation viscosity test was used to ascertain adoption of fiber in AR-SMA. Due to the swelling of asphalt rubber mortar, the gap-coarse graded aggregate must be used in asphalt rubber concrete to provide enough free space. This paper reinforces material composition and grade proportion range of adapted AR-SMA depending on special characteristic of this mix. After confirming best grade of AR-SMA, this paper used the Marshall method to design job mix formula (IMF) of AR-SMA13. The best CRM asphalt binder content and feasible gradation middle value were obtained by Marshall Test and volume parameter calculation. In performance evaluation phase, two SMA usually used in Beijing region were added in comparison with AR-SMA. Mechanical properties of AR-SMA mix were evaluated by wheel rutting test(WRT), midpoint beam bending test(MBBT) at low temperatures, indirect tensile strength test(ITST) at various freeze/thaw cycles, Cantabro test, and Schellenburg binder drainage test. The results indicate that the pavement performance of AR-SMA is very excellent, compared to the other two SMA's frequently used in Beijing region.