Extended aging performance of high RAP mixtures and the role of softening oils

ABSTRACT

Recently, there is a growing interest in increasing content of reclaimed asphalt pavement (RAP) material in the production of Hot Mix Asphalt (HMA) pavements to further reduce material costs and to preserve non-renewable resources. This study aims to evaluate the long-term performance of high RAP mixtures containing various softening oils. Both petroleum-based and bio-based oils were applied in preparing the 30% RAP and 50% RAP mixtures. The mixtures were subjected to the short-term oven aging (4 h), long-term oven aging (8 h), and extended-term aging (16 h) in the laboratory. Their performance, including the rutting, fatigue cracking at intermediate temperature, and low temperature cracking, were measured and compared with the control mixtures. The results indicate that the softening oils in this study can be used to produce asphalt mixtures containing high percentages of RAP with similar performance to a virgin mixture utilising the same aggregates and mixture design. In addition, the results show that making decisions to compare, qualify, or otherwise accept mixtures using the short-term aging results alone can be very risky. It is clearly shown in this study that relative ranking of mixture performance can change based on the level of aging.

KEYWORDS:

• Recycled asphalt mixture
• high RAP
• softening oils
• long-term aging
• rutting resistance
• cracking resistance

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Wisconsin Department of Transportation [grant number TPF-5(352)].