ASTM C61/C61M-00(2020)

Standard Specification for Gypsum Keene's Cement

ABSTRACT
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. The cement shall show a combined water content not more than the specified value when tested in accordance with the referenced test method. The cement shall conform to the required physical properties and shall undergo tests on setting time, compressive strength, and fineness.
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-May-2020
• ICS: 91.100.10 - Cement. Gypsum. Lime. Mortar
• Technical Committee: C11 - Gypsum and Related Building Materials and Systems
• Drafting Committee: C11.01 - Specifications and Test Methods for Gypsum Products

Relations

• Replaces: ASTM C61/C61M-00(2015) - Standard Specification for Gypsum Keene's Cement
• Effective Date: 01-Jun-2020
• Refers: ASTM C471M-24 - Standard Test Methods for Chemical Analysis of Gypsum and Gypsum Products (Metric)
• Effective Date: 01-Apr-2024
• Refers: ASTM C472-20 - Standard Test Methods for Physical Testing of Gypsum, Gypsum Plasters, and Gypsum Concrete
• Effective Date: 01-Apr-2020
• Refers: ASTM C11-18a - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 01-Oct-2018
• Refers: ASTM C11-18 - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 01-Jun-2018
• Refers: ASTM C11-17a - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 01-Oct-2017
• Refers: ASTM C471M-17a - Standard Test Methods for Chemical Analysis of Gypsum and Gypsum Products (Metric)
• Effective Date: 01-Oct-2017
• Refers: ASTM C471M-17e1 - Standard Test Methods for Chemical Analysis of Gypsum and Gypsum Products (Metric)
• Effective Date: 01-Jun-2017
• Refers: ASTM C471M-17 - Standard Test Methods for Chemical Analysis of Gypsum and Gypsum Products (Metric)
• Effective Date: 01-Jun-2017
• Refers: ASTM C11-17 - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 15-May-2017
• Refers: ASTM C471M-16a - Standard Test Methods for Chemical Analysis of Gypsum and Gypsum Products (Metric)
• Effective Date: 15-Jun-2016
• Refers: ASTM C11-16 - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 15-May-2016
• Refers: ASTM C471M-16 - Standard Test Methods for Chemical Analysis of Gypsum and Gypsum Products (Metric)
• Effective Date: 01-Jan-2016
• Refers: ASTM C11-15a - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 01-Oct-2015
• Refers: ASTM C11-15 - Standard Terminology Relating to Gypsum and Related Building Materials and Systems
• Effective Date: 01-Apr-2015

Overview

ASTM C61/C61M-00(2020) – Standard Specification for Gypsum Keene’s Cement defines requirements for various grades of anhydrous calcined gypsum, commonly known as gypsum Keene’s cement. Developed by ASTM International, this standard is intended for manufacturers, purchasers, and users of gypsum plaster in both base and finish coats. The specification ensures that Keene’s cement products meet stringent criteria for performance and consistency, supporting durable construction and high-quality decorative finishes.

Gypsum Keene’s cement is primarily valued for its hard, dense finish and is available in quick-setting and standard-setting types, as well as grades with varied fineness and setting times. The standard sets out the testing and certification processes to confirm that products comply with all necessary physical and chemical requirements.

Key Topics

• Grades and Types: Outlines available grades of gypsum Keene’s cement, focusing on quick-setting and standard-setting varieties with different degrees of fineness and setting times.
• Physical Properties: Specifies minimum requirements:
  • Combined water content: Must not exceed specified limits (not more than 2%).
  • Compressive strength: Must meet or exceed 2500 psi [17 MPa].
  • Fineness: Material must pass through specified sieves to guarantee uniformity.
  • Setting time: Must fall between 20 minutes and 6 hours depending on test results.
• Testing and Quality Control:
  • Sampling: Guidelines for randomly selecting product samples to ensure compliance.
  • Test Methods: Relies on referenced ASTM test methods for chemical analysis, physical testing, and sieve conformity.
  • Certification: A supplier statement of compliance is required when specified in purchasing agreements.
• Marking and Packaging: Requirements for clear labeling of product identity, compliance, and net weight, as well as ensuring shipment in dry, lump-free packaging.
• Safety and Compliance: Notes that safety, health, and environmental practices must be established by the user; regulatory applicability is determined by the user.
• Units of Measure: Provides for independent use of either SI (metric) or inch-pound units.

Applications

Gypsum Keene’s cement is widely used in the construction and renovation industries, offering practical benefits for:

• Base and Finish Coats in Plaster Systems: Ensures a hard-wearing and highly polished finish for walls and ceilings, frequently chosen for high-traffic areas or decorative applications.
• Scagliola Castings: Serves as a core material for creating marble-like ornamental elements and restoration work in historic or prestigious buildings.
• Special Purpose Plaster: Its variable setting times and fineness enable tailored solutions for complex decorative or architectural projects.
• Commercial, Institutional, and Residential Settings: Suitable for a range of interior applications demanding durable and aesthetically pleasing finished surfaces.

Implementing this standard guarantees that gypsum Keene’s cement products exhibit predictable behavior during installation and performance, minimizing risk and enhancing implementation quality for contractors and builders.

Related Standards

ASTM C61/C61M closely references several other ASTM standards key to quality assurance and testing in gypsum products:

• ASTM C11: Terminology Relating to Gypsum and Related Building Materials and Systems
• ASTM C471M: Test Methods for Chemical Analysis of Gypsum and Gypsum Products
• ASTM C472: Test Methods for Physical Testing of Gypsum, Gypsum Plasters, and Gypsum Concrete
• ASTM E11: Specification for Woven Wire Test Sieve Cloth and Test Sieves

These supporting standards uphold the accuracy, consistency, and reliability of gypsum Keene’s cement as defined in ASTM C61/C61M, making them essential references for laboratories, manufacturers, and quality assurance professionals.

Keywords: anhydrous gypsum, gypsum Keene’s cement, gypsum plaster, Keene’s cement, ASTM C61, plaster specification, construction materials, plaster standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C61/C61M −00 (Reapproved 2020)
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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This specification covers various grades of anhydrous
C11 Terminology Relating to Gypsum and Related Building
calcined gypsum known as gypsum Keene’s cement, designed
Materials and Systems
for use in the base and finish coats of gypsum plaster.
C471M Test Methods for ChemicalAnalysis of Gypsum and
NOTE 1—The setting time is accelerated by the addition of other
Gypsum Products (Metric)
materials.
C472 Test Methods for Physical Testing of Gypsum, Gyp-
NOTE 2—Keene’s cements are generally available as quick-setting and
sum Plasters, and Gypsum Concrete
standard-setting types. However, various grades of gypsum Keene’s
E11 Specification for Woven Wire Test Sieve Cloth and Test
cement of different fineness and setting time are available. Grades
Sieves
intended for use in scagliola castings and other special purposes should
conform to the requirements of this specification in all respects except
3. Terminology
fineness and setting time.
3.1 Definitions:
1.2 The values stated in either inch-pound or SI (metric)
3.1.1 Definitions of terms used in this specification shall be
units are to be regarded separately as standard. Within the text,
as defined in Terminology C11.
the SI units are shown in brackets. The values stated in each
3.2 Definitions of Terms Specific to This Standard:
system shall be used independently of the other. Values from
3.2.1 scagliola, n—an imitation marble used for ornamental
the two systems shall not be combined.
interior work.
1.3 The text of this standard references notes and footnotes
4. Chemical Composition
that provide explanatory material. These notes and footnotes
shall not be considered as requirements of the standard.
4.1 Combined Water—The cement shall show a combined
water content not more than 2 % when tested in accordance
1.4 The following safety hazards caveat pertains only to the
with Test Methods C471M.
test method in the appendix of this specification: This standard
does not purport to address all of the safety concerns, if any,
5. Physical Properties
associated with its use. It is the responsibility of the user of this
5.1 Testing shall be in accordance with Test Methods C472,
standard to establish appropriate safety, health, and environ-
except that in the determination of the setting time and
mental practices and determine the applicability of regulatory
compressive strength, the consistency used shall be such that a
limitations prior to use.
35-g conical plunger, described in Test Methods C472, shall
1.5 This international standard was developed in accor-
give a penetration of 30 6 2 mm, 20 s after release, the
dance with internationally recognized principles on standard-
measurement being made 5 min after the addition of the
ization established in the Decision on Principles for the
gypsum Keene’s cement to the gauging water.
Development of International Standards, Guides and Recom-
5.1.1 Setting Time— The cement shall set in not less than
mendations issued by the World Trade Organization Technical
20 min and not more than 6 h when determined by the Vicat
Barriers to Trade (TBT) Committee.
method.
5.1.2 Compressive Strength—GypsumKeene’scementshall
have a compressive strength of not less than 2500 psi
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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2020. Published June 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1926. Last previous edition approved in 2015 as C61/ Standards volume information, refer to the standard’s Document Summary page on
C61M – 00 (2015). DOI: 10.1520/C0061_C0061M-00R20. the ASTM website.
*A Summary of Changes section appears at the end of this standard
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C61/C61M − 00 (2020)
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