Effects of long term oven aging on RAP mixtures

As the use of Reclaimed Asphalt Pavement in asphalt concrete mixtures increases, it is important to understand how the addition of already aged asphalt binder affects the overall properties and performance of the mixture. In this study, four plant-produced mixtures containing 0%, 20%, 30%, and 40% RAP were long term oven aged in the laboratory to three levels. For each RAP content and aging level, several properties were investigated. These included dynamic modulus, phase angle, relaxation modulus, push pull fatigue with continuum damage analysis, and flow number. In general, as RAP content increased, aging had less of an effect on stiffness. The Global Aging System (GAS) was also used to predict the change in dynamic modulus over time using the virgin binder properties. This method over predicted the measured changes in stiffness. Mixes with 20% RAP had the best fatigue performance. Regardless of the aging level, the addition of RAP increased flow number