Using Recycled Asphalt Pavement in Asphalt Mixtures in Canada

Abstract

Recycled asphalt pavement (RAP) can be used in roadway bituminous mixtures as a cost-effective portioned replacement of virgin aggregate skeleton and asphalt binder. To be successful, mixtures containing RAP should have similar characteristics to mixtures containing 100% virgin materials and should offer equal or better long-term performance under laboratory and field conditions.

Over the past 40 years, RAP mixtures in North America have performed satisfactorily when properly engineered, produced and placed. Field performance of RAP mixtures has been reported to be comparable or better than asphalt mixtures with zero recycled content. However, as RAP use has increased, Canadian agencies have observed signs of premature performance issues including cracking in asphalt pavements. This premature distress is particularly prevalent in mixtures with higher amounts of RAP.

OBJECTIVES

The project would develop a practice-ready report on the use of RAP in asphalt mixtures that can be referenced by Canadian transportation agencies. The report would be based on a review of literature, effective agency practices and input from industry leaders, and would address material management, material characterization, mixture design, plant production, and laydown of asphalt mixes produced with RAP to ensure proper performance. Asphalt mixes include both hot and warm mix, and quality, health, climate and environmental impacts should be specified for each aspect.

Key project tasks will include:

• Review international literature to summarize industry best practices and guidelines for RAP usage, with a focus on countries that have successfully used high recycled content over the last 20 years
• Summarize and update findings from a 2021 survey of Canadian agencies on their use of RAP in asphalt mixes
• Summarize lessons from a series on online learning events held by TAC’s RAP Working Group
• Development a chapter outlining recommendations for Canadian agencies on how to develop a methodology for testing, recording and sharing performance evaluations of innovations or new approaches for RAP mixes (i.e. elements to be included to ensure controls to document performance, allowing agencies to compare similarly and how to improve practices)