ASTM C09.40 eyes standard for recycling returned ready mixed

Source: ASTM International, West Conshohocken, Pa.

A proposed standard, WK39876, Specification for Returned Fresh Concrete for Use in a New Batch of Ready-Mixed Concrete, will cover process, verification and record keeping procedures for recycling mixes.

A significant amount of concrete is returned to plants, ASTM Subcommittee C09.40 on Ready-Mixed Concrete notes, resulting in wasted material, the need for disposal and unnecessary environmental impact. Those issues can be minimized since some of the returned concrete is suitable for reuse and can be incorporated into new batches. An ASTM standard could ensure that returned fresh concrete mixed with new concrete has user-specified characteristics.

“The proposed standard will help ready mixed concrete producers reduce waste material and disposal requirements,” says Eric Koehler, vice president of Verifi LLC and chairman of the task group developing ASTM WK39876. “Purchasers and specifiers of concrete can obtain concrete with greater recycled content while ensuring the concrete is of high quality.”

Koehler notes that technology available to facilitate the reuse of returned fresh concrete includes hydration-stabilizing admixtures that can be used to extend the setting time of concrete and ensure that concrete can be used in a new batch. In addition, truck-mounted equipment can be used to measure, manage and record concrete slump, water content, temperature and load size throughout the delivery cycle to reduce the need for manual testing.

Subcommittee C09.40 welcomes all stakeholders, particularly those with experience in using returned fresh concrete, to contribute to ASTM WK39876 development. The task force will convene next during the ASTM Committee C09 week, June 9–12 in Indianapolis. Contacts: (technical) Eric Koehler, 617/498-4354; [email protected]; (ASTM staff, committee liaison) Scott Orthey, 610/832-9730; [email protected].