Influence of different rejuvenating agents on rheological behavior and dynamic response of recycled asphalt mixtures incorporating 60% RAP dosage

Abstract

Utilizing reclaimed asphalt pavement (RAP) to produce recycled asphalt mixture is gaining great interests due to landfill space reduction and saving of natural resources. This study investigated the influence of different rejuvenators on rheological behavior of the aged binder and dynamic response of recycled asphalt mixtures incorporating 60% RAP dosage. The frequency sweep test and steady state shear test were performed by Dynamic Shear Rheometer (DSR) to characterize the rheological behavior of different rejuvenated binders. Dynamic response behaviors of recycling asphalt mixtures, including dynamic modulus, phase angle, fatigue, were evaluated by using Simple Performance Test (SPT) and Four-Point Bending Test (4 PB). Analysis on the experimental results showed that the rheological behavior of the aged binder can be restored by incorporating appropriate rejuvenating agents, such as vegetable oil and composite rejuvenator. The three-point bending test revealed that the viscosity level was an important factor to influence the cracking resistance of recycled asphalt mixtures containing high RAP dosage. Due to a high RAP dosage, the dynamic modulus of recycled asphalt mixture was increased while the fatigue life was reduced. The incorporation of rejuvenating agents can restore the visco-elastic behavior of recycled asphalt mixtures, but it was difficult to recover the dynamic modulus and fatigue life to similar level as that of the new asphalt mixture. Among the four rejuvenating agents used in this research, the composite rejuvenator obtained the best overall performance.