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July/August 2010
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Mechanical sampling device in use. Photo courtesy of HMA Lab Supply and the Shelly Co.

Sampling Methods

Safety concerns and the need to obtain representative samples are the driving forces behind a proposed new standard being developed by ASTM International Committee D04 on Road and Paving Materials. The proposed new standard, WK26774, Practice for Sampling Bituminous Paving Material from a Truck by Means of a Mechanical Sampling Device, is under the jurisdiction of Subcommittee D04.30 on Methods of Sampling.

“It’s almost physically impossible to get a true representative sample from a truck bed by just leaning over the edge with a shovel,” says John Muhlke, D04 member and owner, HMA Lab Supply Inc. “Technicians constantly place themselves at risk for possibly falling into the truck bed while overextending their reach.”

According to Muhlke, the proposed test method will enable a user to collect a more useful sample from almost any location within the truck bed and deposit it in a sample collection device sitting on the ground.

“Manual sampling, more often than not, will collect samples that have been segregated by the loading process, and these samples will not yield accurate test results,” says Muhlke. The procedures described in the proposed new standard will allow the user to do the collection without having to approach the side of the truck bed and in a much more timely and accurate manner than if the collection were done manually.

Asphalt producers wishing to obtain better samples in a safer way will be the primary users of WK26774 once it has been approved.

Brian Johnson, chairman of D04.30 and accredidation program supervisor at the American Association of State Highway and Transportation Officials Materials Reference Laboratory, says that participation is always welcome. In addition to work on WK26774, the subcommittee is currently engaged in updating its standards with high resolution photos or updated diagrams.

CONTACT

Technical Information: Brian Johnson, AASHTO Materials Reference Laboratory, Gaithersburg, Md.

Phone: 301-975-6423

ASTM Staff: Daniel Smith

Phone: 610-832-9727