Stiffness and Fatigue Properties of Modified Asphalt Mixes with Waste Plastic Bottles (PET)

In this study، the stiffness and fatigue properties of asphalt concrete mixtures، modified by waste plastic bottles (PET) have been evaluated. Different amounts of PET (2% up to 10% by weight of bitumen) was added by dry process to the mix and the resilient modulus and fatigue tests at 5 and 20 °C were performed. The results showed that low amount of PET (up to 2% by weight of the bitumen) increases the stiffness and results are then descending. It also tends to harden the asphalt mixture at low temperature، the addition of PET to reduce its hardness. At high amount of PET (especially 8% and 10%)، fatigue life of mixtures increased more and the relationship between fatigue life and initial strain shows that at high loading conditions، fatigue failure will be more critical، at low to moderate temperatures. On the contrary، at lower loading conditions where the strain values are less than about 160–210 microstrain، the fatigue failure is not critical at low temperatures.