Admixtures save concrete installers a variety of headaches. They are added to concrete mix to increase strength or shorten curing time of blocks and pavers. They can minimize cracks from drying shrinkage when added to fresh concrete for tilt-up slabs, lift slabs, or slabs cast over membrane. Some produce desired setting time and finishing characteristics.

To discuss possible standards for new “self-compacting concrete” admixtures, ASTM Committee C09 on Concrete and Concrete Aggregates invites engineering professors, admixture manufacturers, precast and pre-stressed concrete producers, consulting engineers, and transportation officials to an organizational meeting on Tuesday, June 26, 5 p.m., Marriott Hotel, Norfolk, Va.

At the meeting, specific standard requirements for self-compacting concrete admixtures, a proposed title and scope for a basic standard, and the creation of working groups under a possible subcommittee for self-compacting concrete will be considered.

The new class of self-compacting concrete admixtures has profound performance differences than its predecessors and is significantly changing the way precast and pre-stressed concrete is manufactured, according to Fred Kinney of Committee C09.

“This new class of admixture far outperforms conventional high range water reducers in precast concrete,” said Kinney, who manages the Technical Center for ESSROC Cement, Ohio. “It is not only a more efficient concrete water reducer, and is not retarding, but it also can modify the plastic concrete rheological properties so that it flows ‘like water’ while not letting the material segregate. This unique combination of properties reduces casting time, curing time, and totally eliminates the need for consolidation of precast and prestressed concrete.

“The actual molecules used for this additive have been in development for more than 20 years and just recently someone got it right,” he continued. “Because of the unique performance of this class of additive it was suggested by Sid Freeman of PCI [Precast/Prestressed Concrete Institute, a national representative body] that a new subcommittee be considered to develop standards and test methods that would standardize and quantify the materials and their use.”

For further technical information, contact the organizing chair: Frederick D. Kinney, Manager, Technical Center, ESSROC Cement, Middlebranch, Ohio (phone: 330/966-8415). Committee C09 meets June 24-27 in Norfolk. For meeting or membership details, contact Staff Manager Jim Olshefsky, ASTM (phone: 610/832-9714). //

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