Strategies to improve performance of reclaimed asphalt pavement-recycled asphalt shingle mixtures

ABSTRACT

Recycling highway construction materials and minimising the use of virgin materials can reduce the pavement life cycle costs, improve highway network condition, conserve natural resources, and protect the environment. However, aged binder in reclaimed asphalt pavement (RAP) and recycled asphalt shingle (RAS) makes asphalt pavements more brittle and creates long-term durability problems. In this study, the performance benefits of using softer virgin binder grade and increased virgin binder content strategies in RAP and RAS mixture production in Oregon were quantified. Semi-circular bend and flow number tests were conducted on prepared samples in laboratory to assess their cracking and rutting performance with low or no RAP (0% and 15%), high RAP (30% and 40%), and RAP&RAS, three binder contents (total binder contents with RAP/RAS and virgin binder – 6%, 6.4%, and 6.8%), and three binder grades (PG 58-34, PG 64-22, and PG 76-22). Moreover, possible combinations of RAP/RAS content, binder content, and binder grade to produce asphalt mixtures with high cracking and rutting performances were suggested using regression modelling and sensitivity analysis. The results of this study show that increasing binder content does not create any significant impact on the cracking performance of RAP&RAS mixtures but it is an effective strategy to improve the fatigue cracking resistance of 30% and 40% RAP mixtures.

KEYWORDS:

• Recycling
• reclaimed asphalt pavement
• recycled asphalt shingle
• high binder content
• semi-circular bend
• flow number
• rutting and cracking

Acknowledgment

This paper describes research activities that were requested and sponsored by the Oregon Department of Transportation (ODOT). The contents of this paper reflect the views of the authors and do not reflect the official views or policies of the State of Oregon or Federal Highway Administration. Federal and State sponsorship and interest are gratefully acknowledged. The authors thank the members of the ODOT Project Technical Advisory Committee and ODOT research for their advice and assistance. The authors would like to thank Blaine Wruck, Tim Flowerday, Nicholas Kolstad, John Paul Morton, Andrew Johnson, Mostafa Estaji, Ihsan Obaid, Natasha Anisimova, Matthew Haynes, and Jawad Qassem for their help with sieving, batching, and measuring theoretical maximum specific gravity of prepared samples, as well as James Batti for his help in the laboratory.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 Binder content.

Additional information

Funding

This work was supported by Oregon Department of Transportation [grant number 30530-16-10].