ASTM C61/C61M-00(2015)

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Designation: C61/C61M − 00 (Reapproved 2011) C61/C61M − 00 (Reapproved 2015)
Standard Specification for
Gypsum Keene’s Cement
This standard is issued under the fixed designation C61/C61M; 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 U.S. 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.
1.2 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.
1.3 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
C471M Test Methods for Chemical Analysis of Gypsum and Gypsum Products (Metric)
C472 Test Methods for Physical Testing of Gypsum, Gypsum Plasters and Gypsum Concrete
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
3. Terminology
3.1 Definitions—Definitions of terms used in this specification shall be as defined in Terminology C11.
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—The cement shall show a combined water content not more than 2 % when tested in accordance with Test
Methods C471M.
5. Physical Properties
5.1 Testing shall be in accordance with Test Methods C472, except that in the determination of the setting time and compressive
strength, the consistency used shall be such that a 35–g conical plunger, described in Test Methods C472, 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.
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 May 1, 2011Oct. 1, 2015. Published May 2011October 2015. Originally approved in 1926. Last previous edition approved in 20062011 as
C61/C61M – 00 (2006).(2011). DOI: 10.1520/C0061_C0061M-00R11.10.1520/C0061_C0061M-00R15.
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*A Summary of Changes section appears at the end of this standard
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C61/C61M − 00 (2015)
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.
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 compress
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