While the effort has been in place for a while, ASTM Subcommittee C09.40, responsible for standards for ready mixed concrete including ASTM C94 and C685, has developed a preliminary specification to address reuse of returned fresh (plastic) concrete. The proposed standard, ASTM WK39876, Specification for Returned Fresh Concrete for Use in a New Batch of Ready-Mixed Concrete, will be issued as a subcommittee ballot to begin the standardization process.

"Concrete is the most widely used building material in the world," says Eric Koehler, vice president, Verifi LLC, and chairman of the task group developing ASTM WK39876. "The proposed standard will help ready mixed concrete manufacturers reduce waste material and disposal requirements. 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.

After the first ballot is issued, resolution to the comments will be addressed by the task group and the subcommittee at the next ASTM meeting of Committee C09 on Concrete and Aggregates, June 9-12 in Indianapolis.