Using Recycled Asphalt Shingles with Warm Mix Asphalt Technologies

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 890: Using Recycled Asphalt Shingles with Warm Mix Asphalt Technologies documents the development of a design and evaluation procedure that provides acceptable performance of asphalt mixtures incorporating warm mix asphalt (WMA) technologies and recycled asphalt shingles (RAS)—with and without recycled asphalt pavement (RAP)—for project-specific service conditions.

Since the introduction of the first WMA technologies in the U.S. about a decade ago, it has quickly become widely used due to reduced emissions and production costs of mixing asphalt at a lower temperature. The use of RAS has increased significantly over the past 10 years primarily due to spikes in virgin asphalt prices between 2008 and 2015. The report addresses the amount of mixing between RAS binders and virgin binders when WMA is used. 

It provides additional guidance for designing, producing, and constructing asphalt mixtures that use both RAS and WMA to address several gaps in the state-of-the-knowledge on how these two technologies work, or perhaps, don’t work together.

The report also identifies ways to minimize the risk of premature failure due to designing and producing mixes containing WMA technologies and RAS with poor constructability and durability.