ASTM C494/C494M-08a

Standard Specification for Chemical Admixtures for Concrete

ABSTRACT
This specification covers the materials and the test methods for use in chemical admixtures to be added to hydraulic-cement concrete mixtures in the field. The seven types of admixtures are indicated as follows: Type A—water reducing; Type B—retarding; Type C—accelerating; Type D—water reducing and retarding; Type E—water reducing and accelerating; Type F—water reducing, high range; and Type G—water reducing, high range, and retarding. The materials used in the concrete mixtures shall include Type I or Type II cement, pozzolan, fine and coarse aggregates, and air-entraining admixture. Samples of freshly mixed concrete from at least three separate batches for each condition of concrete shall be tested in accordance with the slump, air content, time of setting, and water content tests. Physical properties retesting shall consist of uniformity and equivalence tests using infrared analysis which is intended to compare qualitatively the composition of different samples, residue by oven drying which shall be either a forced circulation type or one with provision for free access of air, and specific gravity determination using hydrometers. Test specimens of the hardened concrete shall be prepared in accordance to compressive strength, flexural strength, resistance to freezing and thawing, and length change.
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 purposes indicated for the eight 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,  
1.1.7 Type G—Water-reducing, high range, and retarding admixtures, and
1.1.8 Type S—Specific performance 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.
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.  
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...

General Information

• Status: Historical
• Publication Date: 31-Aug-2008
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.23 - Chemical Admixtures

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation: C494/C494M – 08a
Standard Specification for
1
Chemical Admixtures for Concrete
This standard is issued under the fixed designation C494/C494M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
NOTE 3—Admixtures that contain relatively large amounts of chloride
1. Scope*
may accelerate corrosion of prestressing steel. Compliance with the
1.1 This specification covers materials for use as chemical
requirements of this specification does not constitute assurance of accept-
admixtures to be added to hydraulic-cement concrete mixtures
ability of the admixture for use in prestressed concrete.
in the field for the purpose or purposes indicated for the eight
1.3 This specification provides for three levels of testing.
types as follows:
1.3.1 Level 1—During the initial approval stage, proof of
1.1.1 Type A—Water-reducing admixtures,
compliance with the performance requirements defined in
1.1.2 Type B—Retarding admixtures,
Table 1 demonstrates that the admixture meets the require-
1.1.3 Type C—Accelerating admixtures,
mentsofthisspecification.Admixtures(exceptforTypesB,C,
1.1.4 Type D—Water-reducing and retarding admixtures,
E, and S) shall qualify for provisional compliance when the
1.1.5 Type E—Water-reducing and accelerating admixtures,
physical requirements and any of the alternative compressive
1.1.6 Type F—Water-reducing, high range admixtures,
strength requirements in Table 1 are met. If subsequent test
1.1.7 Type G—Water-reducing, high range, and retarding
results at 6 months or one year fail to meet the standard
admixtures, and
requirement of 100% of reference strength, the compliance of
1.1.8 Type S—Specific performance admixtures.
theadmixturetothisstandardiswithdrawnandallusersofthe
1.2 This specification stipulates tests of an admixture with
admixture shall be notified immediately. Uniformity and
suitable concreting materials as described in 11.1-11.3 or with
equivalence tests of Section 6 shall be carried out to provide
cement, pozzolan, aggregates, and an air-entraining admixture
resultsagainstwhichlatercomparisonscanbemade(SeeNote
proposed for specific work (11.4). Unless specified otherwise
4).
by the purchaser, the tests shall be made using concreting
materials as described in 11.1-11.3. NOTE 4—Allowing for provisional compliance while retaining longer
termcompressivestrengthrequirementspromotesmorerapidqualification
NOTE 1—It is recommended that, whenever practicable, tests be made
of new materials, but also provides assurance that new admixture
using the cement, pozzolan, aggregates, air-entraining admixture, and the
technologies will not exhibit unexpected longer term performance. The
mixture proportions, batching sequence, and other physical conditions
alternative compressive strength requirements in Table 1 are based on
proposedforthespecificwork(11.4)becausethespecificeffectsproduced
statisticalanalysisof103SpecificationC494/C494Mevaluationtests.The
by chemical admixtures may vary with the properties and proportions of
alternative requirements correspond to a 99% probability of passing
the other ingredients of the concrete. For instance, Types F and G
2
subsequent test age requirements.
admixturesmayexhibitmuchhigherwaterreductioninconcretemixtures
1.3.2 Level 2—Limited retesting is described in 5.2, 5.2.1
having higher cement factors than that listed in 12.1.1.
Mixtureshavingahighrangewaterreductiongenerallydisplayahigher and 5.2.2. Proof of compliance with the requirements of Table
rate of slump loss. When high-range admixtures are used to impart
1demonstratescontinuedconformityoftheadmixturewiththe
increased workability (6 to 8-in. slump [150 to 200–mm]), the effect may
requirements of the specification.
be of limited duration, reverting to the original slump in 30 to 60 min
1.3.3 Level 3—For acceptance of a lot or for measuring
depending on factors normally affecting rate of slump loss. The use of
uniformity within or between lots, when specified by the
chemical admixtures to produce high-slump (flowing) concrete is covered
purchaser, the uniformity and equivalence tests of Section 6
by Specification C1017/C1017M.
shall be used.
NOTE 2—The purchaser should ensure that the admixture supplied for
use in the work is equivalent in composition to the admixture subjected to
1.4 The values stated in either SI units or inch-pound units
test under this specification (see Section 6, Uniformity and Equivalence).
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; there
...