ASTM C61/C61M-00(2006)

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Designation:C61/C61M–00 Designation: C 61/C 61M – 00 (Reapproved 2006)
Standard Specification for
Gypsum Keene’s Cement
This standard is issued under the fixed designation C 61/C 61M; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope *
1.1 This specification covers various grades of anhydrous calcined gypsum known as gypsum Keene’s cement, designed for use
in the base and finish coats of gypsum plaster.
NOTE 1—The setting time is accelerated by the addition of other materials.
NOTE 2—Keene’s cements are generally available as quick-setting and standard-setting types. However, various grades of gypsum Keene’s cement of
different fineness and setting time are available. Grades intended for use in scagliola castings and other special purposes should conform to the
requirements of this specification in all respects except fineness and setting time.
1.2The1.2 The values stated in either inch-pound or SI (metric) units are to be regarded separately as standard. Within the text,
the SI units are shown in brackets. The values stated in each system shall be used independently of the other. Values from the two
systems shall not be combined.
1.3The1.3 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes
shall not be considered as requirements of the standard.
1.4 The following safety hazards caveat pertains only to the test method in the appendix 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.
2. Referenced Documents
2.1 ASTM Standards:
C11 Terminology Relating to Gypsum and Related Building Materials and Systems
C 471M Test Methods for Chemical Analysis of Gypsum and Gypsum Products (Metric)
C 472 Test Methods for Physical Testing of Gypsum, Gypsum Plasters,Plasters and Gypsum Concrete
E11 Specification for Wire- Cloth and Sieves for Testing Purposes
3. Terminology
3.1 Definitions—Definitions of terms used in this specification shall be as defined in Terminology C 11.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 scagliola, n—an imitation marble used for ornamental interior work.
4. Chemical Composition
4.1 Combined Water—Thecementshallshowacombinedwatercontentnotmorethan2 %whentestedinaccordancewithTest
Methods C 471M.
5. Physical Properties
5.1 TestingshallbeinaccordancewithTestMethodsC 472,exceptthatinthedeterminationofthesettingtimeandcompressive
strength, the consistency used shall be such that a 35–g conical plunger, described in Test Methods C 472, shall give a penetration
of 30 6 2 mm, 20 s after release, the measurement being made 5 min after the addition of the gypsum Keene’s cement to the
gauging water.
5.1.1 Setting Time— The cement shall set in not less than 20 min and not more than 6 h when determined by the Vicat method.
This specification is under the jurisdiction of ASTM Committee C11 on Gypsum and Related Building Materials and Systems and is the direct responsibility of
Subcommittee C11.01 on Specifications and Test Methods for Gypsum Products .
Current edition approved July 10, 2000. Published August 2000. Originally published as C61–26T. Last previous edition C61–95.
Current edition approved May 1, 2006. Published May 2006. Originally approved in 1926. Last previous edition approved in 2000 as C 61/C 61M – 00.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 04.01.volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard.
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C 61/C 61M – 00 (2006)
5.1.2 Compressive Strength—Gypsum Keene’s cement shall have a compressive strength of not less than 2500 psi [17 MPa].
Soak standard Keene’s cement in water for 20 min with occasional stirring before filling the mold in the compressive strength
determination.
5.1.3 Fineness—The cement shall all pass a No. 14 [1.40 mm] sieve; not less than 98 % shall pass a No. 40 [425–µm] sieve,
and not less than 80 % shall pass a No. 100 [150–µm] sieve.
6. Sampling
6.1 Randomly select not less than 1 % of the packages, but not
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