||Concrete Industry Invited to Discuss Standardization of Self-Compacting
Concrete Admixtures at June Meeting
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). //
Copyright 2001, ASTM