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ASTM subcommittee eyes tests for RCC compaction, density, air and flexural strength

Source: ASTM International, West Conshohocken, Pa.

ASTM Subcommittee C09.45 on Roller-Compacted Concrete is working on three proposed standards: WK33682, Test Method for Preparation, Compaction and Density Determination of Roller-Compacted Concrete Specimens by Means of the Gyratory Compactor; WK41101, Practice for Molding Roller-Compacted Concrete in Beam Molds Using a Vibrating Hammer; and, WK42461, Test Method for Density (Unit Weight) and Air Content (Pressure Method) of Freshly Mixed Roller-Compacted Concrete.

University of Arkansas Center for Training Transportation Professionals Director Stacy Williams, Ph.D., notes that the Superpave gyratory compactor was developed during the 1980s as a means to provide a laboratory simulation of the compactive effort imparted by rollers on an asphalt mat. RCC is compacted using the same type of roller, so preparing concrete specimens in a laboratory can be expected to provide similar results to those experienced in the field.

WK33682 is being developed to establish a protocol for preparing RCC laboratory specimens that more adequately represent field mixes. “The most practical application is that you can use the gyratory-compacted specimens for determining density,” says Williams. “Strength and density are key performance parameters for RCC; increases in these properties lead to increases in performance.”

WK41101 will be used to consolidate mixes into beam molds with established flexural strengths, a key data point owing to RCC’s emergence as a pavement choice for roads, shoulders and streets. WK42461 covers determination of fresh mixes’ density and air content, and will be used in RCC mix design and to augment quality control during pavement construction.

Subcommittee C09.45 is part of ASTM Committee C09 on Concrete and Concrete Aggregates; members of both will convene December 8–11 in Jacksonville, Fla. Contacts: Stacy Williams (technical), 479/575-2220, sgwill@uark.edu; Scott Orthey (ASTM staff liaison), 610/832-9730, sorthey@astm.org.