Asphalt Recovery

A proposed new ASTM International standard will be used for testing the asphalt used in common pavements. WK40799, Practice for Recovery of Asphalt from Solution Using Toluene and the Rotary Evaporator, is being developed by Subcommittee D04.25 on Analysis of Bituminous Mixtures, part of ASTM International Committee D04 on Road and Paving Materials.

Asphalt pavements comprise mostly liquid asphalt binder (bitumen) and aggregates, which are blended differently (coarse, fine, open, dense) for various needs. Asphalt binder is also graded to meet different climatic and load requirements.

"For example, different liquid binders are used for cold, rural areas, as compared to hot, urban environments," says Phillip Blankenship, senior research engineer, Asphalt Institute, and a D04 member.

WK40799 will provide laboratories with the instructions to extract liquid asphalt bitumen from asphalt-aggregate mixture using toluene and a rotary evaporator. The practice is designed to minimize changes in the asphalt properties during the recovery process.

After the liquid asphalt has been recovered, its properties can be measured to understand the performance of an in-place pavement. Additionally, the proposed standard will allow the recovery of bitumen in reclaimed asphalt pavement and recycled asphalt shingles.

"This proposed standard promotes a more consistent measurement of the recovered liquid binder using a rotary evaporator," says Blankenship.

Once approved, the proposed standard will be used by private, research and consulting laboratories as well as departments of transportation. Interested parties are invited to join in the standards developing activities of D04.25. The subcommittee will eventually be seeking laboratories to participate in interlaboratory testing of WK40799.

CONTACT Technical Information: Phillip Blankenship, PE, Asphalt Institute • Lexington, Ky. • Phone: 859-288-4986 | ASTM Staff: Daniel Smith • Phone: 610-832-9727 | Upcoming Meeting: June 24-26 • June Committee Week • Toronto, Ontario, Canada

Rotovapor asphalt recovery procedure.

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