RAP and the Aging of Asphalt Concrete

The primary reason for limited use of reclaimed asphalt pavement (RAP) is the uncertainty of the long-term pavement performance. Understanding the response of virgin material and RAP material to oxidative aging is important to the selection of virgin and RAP binder. Five different percentages (0%, 15%, 25%, 35% and 40%) of RAP included asphalt concrete (AC) were designed to compare the effects of aging on hot mix asphalt (HMA). To assess the effect of aging on AC, the samples were subjected to oven aging following AASHTO R30 protocol. Successive aging the samples were conducted to quantify which RAP percentage is more susceptible to long-term aging. Dynamic modulus tests were conducted on control and aged AC samples. Results show aging of the material increases the complex modulus of all the samples irrespective of RAP percentages. The master curves indicates that as more RAP is added to the mixes, the curves shift upwards at the high frequency and a slight upward shift at the low frequency end of the curve.