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Designation: C 494/C 494M – 99ae1

Standard Specification for

Chemical Admixtures for Concrete1
This standard is issued under the fixed designation C 494/C 494M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon(e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.

e1 NOTE—Range value in 12.2.2 was editorially corrected July 2001.

1. Scope
1.1 This specification covers materials for use as chemical
admixtures to be added to hydraulic-cement concrete mixtures
in the field for the purpose or purposesindicated for the seven
types as follows:
1.1.1 Type A—Water-reducing admixtures,
1.1.2 Type B—Retarding admixtures,
1.1.3 Type C—Accelerating admixtures,
1.1.4 Type D—Water-reducing and retarding admixtures,
1.1.5 Type E—Water-reducing and accelerating admixtures,
1.1.6 Type F—Water-reducing, high range admixtures, and
1.1.7 Type G—Water-reducing, high range, and retarding
admixtures.1.2 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.

requirements of this specification does notconstitute assurance of acceptibility of the admixture for use in prestressed concrete.

1.3 This specification provides for three levels of testing.
1.3.1 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. Uniformity and equivalence tests of
Section 6 shall becarried out to provide results against which
later comparisons can be made.
1.3.2 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.
1.3.3 Level 3—For acceptance of a lot or for measuring
uniformity within or between lots, whenspecified by the
purchaser, the uniformity and equivalence tests of Section 6
shall be used.
1.4 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.
1.5 The text of this standard references notesand footnotes
which provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered
as requirements of the standard.
1.6 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 itsuse. 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.

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 conditionsproposed 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...