W. CONSHOHOCKEN, PA. — Formalizing a method for making a cylindrical specimen of roller-compacted concrete in a gyratory compactor is the primary purpose of a proposed new ASTM International standard. Roller-compacted concrete pavements are made up of concrete materials but are constructed like asphalt pavement: the mixture is placed with a paver and then compacted with rollers.

ASTM WK33682, Test Method for Preparation, Compaction and Density Determination of Roller-Compacted Concrete Specimens by Means of the Superpave Gyratory Compactor, is being developed by Subcommittee C09.45 on Roller-Compacted Concrete, part of ASTM International Committee C09 on Concrete and Concrete Aggregates.

Stacy G. Williams, Ph.D., P.E., Center for Training Transportation Professionals, and a C09 member, says that the superpave gyratory compactor, developed about 20 years ago, mimics the kneading compaction mechanism that takes place during field compaction.

“The superpave gyratory compactor represented a major shift in the way that asphalt mixtures were designed,” says Williams. “We are always looking for ways to get better correlations between field and laboratory material properties in order to close the gap between the design and production phases of construction. Since RCC pavements are compacted just like asphalt pavements, it seems reasonable that a laboratory-scale compactor designed to imitate field roller compaction would also be appropriate for RCC.”

Once approved, the proposed new standard will be used by RCC mix designers. “Because the gyratory compactor is primarily used in the asphalt industry, I would suspect it will be most applicable to contractors/designers who take part in both the asphalt and concrete industries,” says Williams.

Interested parties, particularly those with experience working with RCC, are invited to participate in the ongoing development of ASTM WK33682.