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Frequently Asked Questions
Cement & Concrete
Technology Home > FAQs > SCC
Q: What is Self-Consolidating Concrete (SCC) and
how is it tested?
A: Self-Consolidating concrete (SCC)
is a high-performance concrete that can flow easily into tight and
constricted spaces without segregating and without requiring vibration.
The key to creating self-consolidating concrete (SCC), also referred
to as self-compacting, self-leveling, or self-placing concrete,
is a mixture that is fluid, but also, stable, to prevent segregation.
To achieve the desired flowability a new generation of superplasticizers
based on polycarboxylate ethers works best. Developed in the 1990s,
they produce better water reduction and slower slump loss than traditional
superplasticizers. The required level of fluidity is greatly influenced
by the particular application under consideration. Obviously the
most congested structural members demand the highest fluidity. However,
element shape, desired surface finish, and travel distance can also
determine the required fluidity.
Generally, the higher the required flowability of the SCC mix,
the higher the amount of fine material needed to produce a stable
mixture. However, in some cases, a viscosity-modifying admixture
(VMA) can be used instead of, or in combination with, an increased
fine content to stabilize the concrete mixture.
Test Methods
SCC is characterized by its unique fresh concrete properties. Therefore,
new test methods are being developed to characterize SCC properties.
See table for test methods approved or under consideration at ASTM:
| Test Method |
Description |
| Slump Flow |
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ASTM C 1611
Test is performed similar to the conventional slump test (ASTM
C 143) using the Abrams cone (use of inverted cone possible).
However, instead of measuring the slumping distance vertically,
the mean spread of the resulting concrete patty is measured
horizontally. This number is recorded as the slump flow.
Measured characteristic: Filling ability (deformability)
& stability
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| J-Ring |
 |
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ASTM C 1621
The J-Ring consists of a ring of reinforcing bar such that it
will fit around the base of a standard slump cone. The slump
flow with and without J-Ring is measured, and the difference
calculated.
Measured characteristic: Passing ability
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| Column Segregation |
 |
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ASTM C 1610
Test evaluates static stability of a concrete mixture by quantifying
aggregate segregation. A column is filled with concrete and
allowed to sit for awhile after placement. The column is then
separated into three or four pieces. Each section is removed
individually and the concrete from that section is washed over
a No. 4 sieve and the retained aggregate weighed. A non-segregating
mix will have a consistent aggregate mass distribution in each
section. A segregating mix will have higher concentrations of
aggregate in the lower sections.
Measured characteristic: Stability
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Additional Resources: (Click on title for link)
NRMCA, CIP
37—Self-Consolidating Concrete, Concrete in Practice,
2004
McGovern, M., “Going with the Flow,” Concrete Technology
Today, CT022, Portland Cement Association, Skokie, Illinois,
July 2002, pages 1, 2, and 8. Click
here to download article.
EFNARC guidelines, Specification
and Guidelines for Self-Compacting Concrete
Order Self-Compacting
Concrete: Bibliography of Resources (2nd ed.)
PCA Library Bibliography Series No. 6 (LB06.02) Portland Cement
Association, c2004
for an extensive list of SCC references.
Read More
Interested in Self-Consolidating Grout?
Read Masonry
Today, Vol. 14, No. 2, Winter 2004/2005,
Flow with Show: Self-Consolidating Concrete
Offers New Opportunities for Architectural Concrete
ACI Committee 237, Self-Consolidating Concrete, ACI 237-07,
American Concrete Institute, Farmington Hills, Michigan, 2007, 32
pages
ACBM, Self-Consolidating
Concrete,
RP440, Advanced Cement-Based Materials Center, Evanston, Illinois,
2007, 42,pages.
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