Performance and blending evaluation of asphalt mixtures containing reclaimed asphalt pavement

This study aims to (1) determine an optimum amount of Reclaimed Asphalt Pavement (RAP) such that its addition does not adversely impact the fracture resistance of asphalt mixtures, and (2) determine the amount of RAP binder that is active in the total mix. For this purpose, the asphalt mixtures containing three RAP contents (15, 25 and 35%) and their recovered binders were characterized. The binders were subjected to the performance grading, frequency sweep, multiple stress creep and recovery (MSCR) and linear amplitude sweep (LAS) tests. The mixtures were evaluated using dynamic modulus, Hamburg Wheel Tracking (HWT), Flow Number (FN), Semi Circular Bend (SCB), and Ideal Cracking Tolerance (Ideal-CT). The blending efficiency of the RAP binder was determined using the Hirsch model. Based on the performance results and the relatively low binder content of asphalt mixtures in Qatar, it is recommended to use up to 20% RAP in asphalt mixtures.