Publication Number: FHWA-SA-97-022
Date: April 1997

Shopping for a Superpave Gyratory Compactor? Start with the AASHTO Specifications

The Superpave gyratory compactor is fast becoming standard equipment for highway agencies and contractors alike, which is attracting new vendors to the market. About a half-dozen manufacturers now sell the devices, and this competition should lead to better prices, new features, and other benefits for buyers. But just like with any new and complex piece of equipment, agencies and contractors should shop carefully to ensure that they're buying gyratory compactors compatible with the Superpave system.

The Superpave gyratory compactor, developed under the Strategic Highway Research Program (SHRP), quickly and easily produces specimens for use in measuring the volumetric properties of an asphalt mix, which indicate how well the mix will perform under real-world traffic and environmental conditions. Because the device is small enough to be set up at the job site, it can be used to ensure that the delivered asphalt mix meets the job specifications.

Superpave gyratory compactors must meet the criteria that appear in the American Association of State Highway and Transportation Officials (AASHTO) provisional specification TP4-93, "Standard Method for Preparing and Determining the Density of Hot Mix Asphalt (HMA) Specimens by Means of the SHRP Gyratory Compactor."^* The specification, which discusses the preparation and analysis of Superpave mixes, details exactly how a Superpave gyratory compactor must perform, its capacities and capabilities, and the features it must have.

FHWA's John Bukowski says highway agencies and contractors comparing Superpave gyratory compactors should review the AASHTO specification and ask vendors whether their products comply with the specification. Prospective buyers should also talk with the vendors' other customers.

As the market matures, it will get easier to select a Superpave gyratory compactor, Bukowski says. The expert task group on Superpave mix design procedures is developing protocols that the Superpave regional centers can use to test new Superpave gyratory compactors.

For more information, contact John Bukowski at FHWA (telephone: 202-366-1287; fax: 202-366-7909; email: john.bukowski@fhwa.dot.gov) or Tom Harman at FHWA (telephone: 202-366-0859; fax: 202-366-7909; email: tom.harman@fhwa.dot.gov).

* Published in AASHTO Provisional Specifications (1996) (Publication Code PS-96), available from AASHTO at 444 N. Capitol St., N.W., Suite 249, Washington, D.C. 20001 (telephone: 202-624-5800; fax: 202-624-5806)

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