ASTM C61/C61M-00

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Designation: C 61/C 61M – 00
Standard Specification for
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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 (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.
1. Scope * E 11 Specification for Wire-Cloth and Sieves for Testing
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Purposes
1.1 This specification covers various grades of anhydrous
calcined gypsum known as gypsum Keene’s cement, designed
3. Terminology
for use in the base and finish coats of gypsum plaster.
3.1 Definitions—Definitions of terms used in this specifica-
NOTE 1—The setting time is accelerated by the addition of other
tion shall be as defined in Terminology C 11.
materials.
3.2 Definitions of Terms Specific to This Standard:
NOTE 2—Keene’s cements are generally available as quick-setting and
3.2.1 scagliola, n—an imitation marble used for ornamental
standard-setting types. However, various grades of gypsum Keene’s
interior work.
cement of different fineness and setting time are available. Grades
intended for use in scagliola castings and other special purposes should
4. Chemical Composition
conform to the requirements of this specification in all respects except
fineness and setting time.
4.1 Combined Water—The cement shall show a combined
water content not more than 2 % when tested in accordance
1.2 The values stated in either inch-pound or SI (metric)
with Test Methods C 471.
units are to be regarded separately as standard. Within the text,
the SI units are shown in brackets. The values stated in each
5. Physical Properties
system shall be used independently of the other. Values from
5.1 Testing shall be in accordance withTest Methods C 472,
the two systems shall not be combined.
except that in the determination of the setting time and
1.3 The text of this standard references notes and footnotes
compressive strength, the consistency used shall be such that a
that provide explanatory material. These notes and footnotes
35–g conical plunger, described in Test Methods C 472, shall
shall not be considered as requirements of the standard.
give a penetration of 30 6 2 mm, 20 s after release, the
1.4 The following safety hazards caveat pertains only to
measurement being made 5 min after the addition of the
the test method in the appendix of this specification: This
gypsum Keene’s cement to the gauging water.
standard does not purport to address all of the safety concerns,
5.1.1 Setting Time—Thecementshallsetinnotlessthan20
if any, associated with its use. It is the responsibility of the user
min and not more than 6 h when determined by the Vicat
of this standard to establish appropriate safety and health
method.
practices and determine the applicability of regulatory limita-
5.1.2 Compressive Strength—Gypsum Keene’s cement
tions prior to use.
shall have a compressive strength of not less than 2500 psi [17
2. Referenced Documents
MPa]. Soak standard Keene’s cement in water for 20 min with
occasional stirring before filling the mold in the compressive
2.1 ASTM Standards:
strength determination.
C 11 Terminology Relating to Gypsum and Related Build-
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5.1.3 Fineness—The cement shall all pass a No. 14 [1.40
ing Materials and Systems
mm] sieve; not less than 98 % shall pass a No. 40 [425–µm]
C 471 Test Methods for Chemical Analysis of Gypsum and
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sieve, and not less than 80 % shall pass a No. 100 [150–µm]
Gypsum Products
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sieve.
C 472 Test Methods for Physical Testing of Gypsum, Gyp-
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sum Plasters, and Gypsum Concrete
6. Sampling
6.1 Randomly select not less than 1 % of the packages, but
not less than 5 packages. Take samples of approximately equal
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This specification is under the jurisdiction of ASTM Committee C11 on
amounts from both the outer portion and the center of each
Gypsum and Related Building Materials and Systems and is the direct responsibility
package. Mix the samples so obtained to provide a composite
of Subcommittee C11.01 on Specifications and Test Methods for Gypsum Products.
Current edition approved July 10, 2000. Published August 2000. Originally
published as C 61 – 26 T. Last previous edition C 61 – 95.
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Annual Book of ASTM Standards, Vol 04.01. Detailed requirements for these sieves are given in ASTM Specification E 11.
*A Summary of Changes section appears at the end of this standard.
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C 61/C 61M
sample of not less than 15 lb [6.8 kg]. Immediately place the 10. Packaging and Marking
sam
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