Review of very high-content reclaimed asphalt use in plant-produced pavements: state of the art

Abstract

Asphalt is the most recycled material in the USA at a re-use rate of 99%. However, by average only 10 -20% reclaimed asphalt pavement (RAP) is used in a given mix design and large part of the RAP is degraded for use in lower value applications. The amount of RAP in asphalt mixtures can be significantly increased with the application of good RAP management practice, readily available modern production technologies and advanced knowledge of mix design. This paper summarises the state-of-the-art approaches for increasing the amount of RAP in asphalt mixtures above 40%. The production challenges and common pavement distresses of very high RAP content mixtures are identified and methods to optimise the mix design as well as production technology in order to allow manufacturing of such sustainable mixtures are described. The best practices for RAP management and economic benefits of high RAP use are also discussed.

Determining optimum rejuvenator dose for asphalt recycling based on Superpave performance grade specifications

“…Further research is also necessary to investigate the effect of rejuvenator dose optimization on the mixture performance-related properties. The effects of adding virgin binder and aggregates are likely to impose new challenges, including rejuvenator diffusion into the RAP binder as well as rejuvenator effect on blending of RAP and virgin binder [31,32,3]. Some of these questions are answered in other stages of this research and summarized in short video: http://youtu.be/y-rYvdGiEbY…”

“…One of the main limitations to allow higher RAP recycling is the aged RAP binder. Unless treated, it stiffens the mixture and can cause cracking failures of the pavement [3]. At low RAP content, softer virgin binder can be used to compensate for the aging effect.…”

Warm Mix Asphalt

“…One major advantage of production using WMA technologies is the potential to increase the Reclaimed Asphalt Pavement (RAP) and Reclaimed Asphalt Shingles (RAS) content in mixture (Bonaquist 2011a;Zaumanis and Mallick 2013;Kristjansdottir 2007). Since mixture workability is increased even at reduced temperature, less superheating is required for virgin aggregates when adding RAP and RAS.…”

Warm-Mix Asphalt and Pavement Sustainability: A Review

“…Zaumanis and Mallick [29] reviewed the state-of-the-art approaches for increasing the amount of RAP in asphalt mixtures above 40% and concluded that RAP content can be significantly increased with the application of good RAP management practices, readily available modern production technologies and advanced knowledge of mix design. Case studies from Germany, Netherlands, and South Africa have reported up to 50% RAP content in mixes [12] [21].…”

“…Environmental benefits include reduced emissions and fuel usage associated with extraction and transportation of virgin materials, reduced demands on non-renewable resources, and reduced landfill space for disposal of construction debris [28]. As it were, pushing for mixes having 100% RAP content could create a cycle of reuse that optimizes the utilization of natural resources and makes pavement construction a sustainable process [29]. What is more, the process of reclaiming and processing RAP materials has a very low environmental impact [8].…”