ASPHALTopics | Spring 2020 | VOL 33 | NO 1

RAP processing and fractionation at Capital Paving.
matrix. Using the RAP Binder Ratio in determining the amount
of RAP for the mixture is recommended. This method defines
the total allowable amount of asphalt material from recycled
asphalt present in a mixture based on the total percentage
of asphalt in the mixture. The advantage of the Binder Ratio
versus percent RAP is that the percentage of aged AC in
the mix can be controlled as the AC content of all recycled
products in the mix are accounted for. 3
4. Employing quality control and RAP best management
practices are recommended. The goal of processing RAP
is to make a uniform material that meets the needs of mix
designs that will use RAP as a component. Setting the
crusher top size is a balance between the need to utilize
the material in a range of mix types versus the generation
of additional fines. The primary advantage of fractionating
RAP is that having stockpiles of different RAP sizes provides
more flexibility in meeting mix design requirements.
Sampling, testing, and analysis of the RAP are vital to
good management of this valuable material. For mix
designs using RAP, the data needed from tests on the
RAP include: asphalt binder content of the RAP; gradation
of the aggregate recovered from the RAP; bulk specific
gravity of the RAP aggregate; consensus properties of
the aggregate recovered from the RAP; and for high RAP ››
50
stability machines.
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3
“The ABCs of RAP” – A 2015 OAPC (OHMPA) publication.
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