Investigating the toughness and fatigue behavior of conventional and SBS modified asphalt mixes

Temperature susceptibility is one of the main inherent properties of asphalt binders. Nowadays, polymer materials are extensively utilized to extend the range of service temperature which finally will confine the temperature induced damages in asphalt mixes. The main goal of this research was to investigate the effect of temperature on the toughness index and fatigue properties of SBS modified asphalt mixes. Utilizing a UTM apparatus which equipped with a temperature control chamber, the indirect tensile strength and indirect tensile fatigue tests were carried out at three testing temperatures of −10, 20 and 50 °C. Based on obtained results at lower temperatures toughness index considerably reduced which indicated the lower flexibility of studied mixes. However, toughness index of modified mixes was to some extent higher than that of conventional mixes. Obtained results confirmed that at high loading conditions, fatigue failure will be more critical at low to moderate temperatures. In contrast, at lower loading conditions in which the strain values are less than about 200-250 microstrain the fatigue failure is not critical at low temperatures.