ASTM C28/C28M-00

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Designation: C 28/C 28M – 00
Standard Specification for
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Gypsum Plasters
This standard is issued under the fixed designation C 28/C 28M; 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
3
Purposes
1.1 This specification covers four gypsum plasters; gypsum
mill-mixed plaster, gypsum neat plaster, gypsum wood fibered
3. Terminology
plaster and gypsum gauging plaster.
3.1 Definitions—Definitions shall be in accordance with
1.2 The values stated in either inch-pound or SI (metric)
Terminology C 11.
units are to be regarded separately as the standard. Within the
3.2 Definitions of Terms Specific to This Standard:
text, the SI units are shown in brackets. The values stated in
3.2.1 gypsum gauging plaster for finish coat, n—a calcined
each system shall be used independently of the other. Values
gypsum plaster designed to be mixed with lime putty for the
from the two systems shall not be combined. This paragraph
finish coat.
does not apply to the appendix.
3.2.2 gypsum neat plaster, n—calcined gypsum mixed at
1.3 The text of this standard references notes and footnotes
the mill with other ingredients to control working quality and
which provide explanatory material. These notes and footnotes
setting time.
(excluding those in tables and figures) shall not be considered
3.2.2.1 Discussion—Neat plaster is either fibered or unfi-
as requirements of the standard.
bered. The addition of aggregate is required on the job.
1.4 The following safety hazards caveat pertains only to the
3.2.3 gypsum mill-mixed plaster, n—calcined gypsum plas-
test methods described in the appendix to this specification.
ter, mixed at the mill with a mineral aggregate, designed to
This standard does not purport to address all of the safety
function as a base coat to receive various finish coats.
concerns, if any, associated with its use. It is the responsibility
3.2.3.1 Discussion—Other materials are not prohibited from
of the user of this standard to establish appropriate safety and
being added to control setting time and other desirable working
health practices and determine the applicability of regulatory
properties.
limitations prior to use.
3.2.4 gypsum wood-fibered plaster, n—A calcined gypsum
2. Referenced Documents plaster in which wood fiber is used as an aggregate.
2.1 ASTM Standards:
4. Materials
C 11 Terminology Relating to Gypsum and Related Build-
2 4.1 Calcined Gypsum—Calcined gypsum shall be manufac-
ing Materials and Systems
2 tured from gypsum meeting the requirements of Specification
C 22 Specification for Gypsum
C 22.
C 35 Specification for Inorganic Aggregates for Use in
2 4.2 Vermiculite Aggregate, Specification C 35.
Gypsum Plaster
4.3 Perlite Aggregate, Specification C 35.
C 471M Test Methods for Chemical Analysis of Gypsum
2 4.4 Sand Aggregate, Specification C 35.
and Gypsum Products
4.5 Ottawa Sand, Specification C 778 for 20–30 sand.
C 472 Test Methods for Physical Testing of Gypsum, Gyp-
2 4.6 Wood Fiber, non staining wood fiber.
sum Plasters, and Gypsum Concrete
2
C 778 Specification for Standard Sand
5. Composition
5.1 When tested in accordance with Test Methods C 471M,
calcined gypsum shall contain no less than 66.0 weight %
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CaSO · ⁄2 H O.
2
4
1
This specification is under the jurisdiction of ASTM Committee C11 on
5.2 Aggregate—plasters shall contain a volume of aggregate
Gypsum and Related Building Materials and Systems and is the direct responsibility
not more than that shown in Table 1.
of Subcommittee C11.01 on Specifications and Test Methods for Gypsum Products.
Current edition approved May 10, 2000. Published July 2000. Originally
{1
published as C 28 – 20 T. Last previous edition C 28 – 96 .
2 3
Annual Book of ASTM Standards, Vol 04.01. Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
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C 28/C 28M
TABLE 1 Composition and Physical Properties
B
Composition, Aggregate per 100 lb Compressive Strength
A
Setting Time
of Plaster, not more than not less than
Product Aggregate Type
3 3
ft m hours psi MPa
1
Mill-Mixed Plaster over Lath Base Vermiculite 2 0.057 1 ⁄2 to 8 450 3.1
1
Perlite 2 0.057 1 ⁄2 to 8 600 4.1
1
Sand 2.5 0.071 1 ⁄2to 8 700 4.8
1
Mill-Mixed Plaster over Masonry Vermiculite 3 0.085 1 ⁄2 to 8 325 2.2
1
Perlite 3 0.085 1 ⁄2 to 8 400 2.8
1
Sand 3 0.085 1 ⁄2to 8 400 2.8
C D
Neat Plaster none . . 2 to 16 750 5.2
1
Wood Fibered Pla
...