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ASTM C 494/C 494M Document Information:
Title
Standard Specification for Chemical Admixtures for Concrete
ASTM International
Publication Date:
Jan 1, 2008
Scope:
This specification covers materials for use as chemical
admixtures to be added to hydraulic-cement concrete mixtures in the
field for the purpose or purposes indicated for the seven types as
follows:
Type A—Water-reducing admixtures,
Type B—Retarding admixtures,
Type C—Accelerating admixtures,
Type D—Water-reducing and retarding admixtures,
Type E—Water-reducing and accelerating admixtures,
Type F—Water-reducing, high range admixtures, and
Type G—Water-reducing, high range, and retarding
admixtures.
This specification stipulates tests of an admixture with
suitable concreting materials as described in 11.1-11.3 or with
cement, pozzolan, aggregates, and an air-entraining admixture
proposed for specific work (11.4). Unless specified otherwise by
the purchaser, the tests shall be made using concreting materials
as described in 11.1-11.3.
NOTE 1—It is recommended that, whenever practicable, tests be
made using the cement, pozzolan, aggregates, air-entraining
admixture, and the mixture proportions, batching sequence, and
other physical conditions proposed for the specific work (11.4)
because the specific effects produced by chemical admixtures may
vary with the properties and proportions of the other ingredients
of the concrete. For instance, Types F and G admixtures may exhibit
much higher water reduction in concrete mixtures having higher
cement factors than that listed in 12.1.1.
Mixtures having a high range water reduction generally display a
higher rate of slump loss. When high-range admixtures are used to
impart increased workability (6 to 8-in. slump [150 to 200–mm]),
the effect may be of limited duration, reverting to the original
slump in 30 to 60 min depending on factors normally affecting rate
of slump loss. The use of chemical admixtures to produce high-slump
(flowing) concrete is covered by Specification C 1017.
NOTE 2—The purchaser should ensure that the admixture supplied
for use in the work is equivalent in composition to the admixture
subjected to test under this specification (see Section 6,
Uniformity and Equivalence).
NOTE 3—Admixtures that contain relatively large amounts of
chloride may accelerate corrosion of prestressing steel. Compliance
with the requirements of this specification does not constitute
assurance of acceptability of the admixture for use in prestressed
concrete.
This specification provides for three levels of testing.
Level 1—During the initial approval stage, proof of
compliance with the performance requirements defined in Table 1
demonstrates that the admixture meets the requirements of this
specification. Admixtures (except for Types B, C, and E) shall
qualify for provisional compliance when the physical requirements
and any of the alternative compressive strength requirements in
Table 1 are met. If subsequent test results at 6 months or one year
fail to meet the standard requirement of 100 % of reference
strength, the compliance of the admixture to this standard is
withdrawn and all users of the admixture shall be notified
immediately. Uniformity and equivalence tests of Section 6 shall be
carried out to provide results against which later comparisons can
be made (See Note 4).
NOTE 4—Allowing for provisional compliance while retaining
longer term compressive strength requirements promotes more rapid
qualification of new materials, but also provides assurance that
new admixture technologies will not exhibit unexpected longer term
performance. The alternative compressive strength requirements in
Table 1 are based on statistical analysis of 103 Specification C
494/C 494M evaluation tests. The alternative requirements
correspond to a 99 % probability of passing subsequent test age
requirements.2
Level 2—Limited retesting is described in 5.2, 5.2.1
and 5.2.2. Proof of compliance with the requirements of Table 1
demonstrates continued conformity of the admixture with the
requirements of the specification.
Level 3—For acceptance of a lot or for measuring
uniformity within or between lots, when specified by the purchaser,
the uniformity and equivalence tests of Section 6 shall be
used.
The values stated in either inch-pound or SI units shall be
regarded separately as standard. The values stated in each system
may not be exact equivalents; therefore, each system must be used
independently of the other, without combining values in any
way.
The text of this standard references notes and footnotes which
provide explanatory material. These notes and footnotes (excluding
those in tables and figures) shall not be considered as
requirements of the standard.
The following precautionary caveat pertains only to the test
method sections, Sections 11-18 of this Specification: This
standard does not purport to address all of the safety concerns, if
any, associated with its use. It is the responsibility of the user
of this standard to establish appropriate safety and health
practices and determine the applicability of regulatory limitations
prior to use.
*A Summary of Changes section appears at the end of this
standard.
2 Supporting data have been filed at ASTM
International Headquarters and may be obtained by requesting
Research Report RR: C09-1030.
Keywords:
- accelerating
- chemical admixtures
- concrete
- physical requirements
- retarding
- testing
- water reducing
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