ASTM C11-98

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Designation: C 11 – 98
Standard Terminology Relating to
Gypsum and Related Building Materials and Systems
This standard is issued under the fixed designation C 11; 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.
1. Scope E 337 Test Method for Measuring Humidity With a Psy-
chrometer (The Measurement of Wet- and Dry-Bulb Tem-
1.1 This standard contains terminology relating to gypsum
peratures)
and related building materials and systems. The terms are
generically defined. More specific and expanded definitions
3. Terminology
may appear in appropriate standards.
accelerator, n—a material that will shorten the setting time of
2. Referenced Documents
gypsum plasters.
2.1 ASTM Standards: accessories, n—linear formed metal, metal and paper, or
C 22/C 22M Standard Specification for Gypsum plastic members fabricated for the purpose of forming
C 28 Specification for Gypsum Plasters corners, edges, control joints, or decorative effects in con-
C 35 Specification for Inorganic Aggregates for Use in junction with gypsum board and plaster assemblies.
Gypsum Plaster adhesive, n—a substance capable of holding materials together
C 36 Specification for Gypsum Wallboard by surface attachment.
C 37 Specification for Gypsum Lath admixture, n—a material other than water, aggregate, or
C 52 Specification for Gypsum Partition Tile or Block inorganic cementitious material that is used as an ingredient
C 59 Specification for Gypsum Casting and Molding Plas- in gypsum plaster or cement plaster and is added to the batch
ter immediately before or during job mixing.
C 61 Specification for Gypsum Keene’s Cement aggregate, n—an inert granular material which may be added
C 79 Specification for Gypsum Sheathing Board to gypsum plasters (C 35).
C 317 Specification for Gypsum Concrete all purpose compound, n—a compound formulated and
C 318 Specification for Gypsum Formboard manufactured to serve as a taping or finishing compound, or
C 472 Test Methods for Physical Testing of Gypsum, Gyp- both.
sum Plasters and Gypsum Concrete anhydrite, n—the mineral consisting primarily of anhydrous
C 473 Test Methods for Physical Testing of Gypsum Board calcium sulfate, CaSO .
Products and Gypsum Lath arris (of an arch), n—the outside corner or angle formed by
C 475 Specification for Joint Compound and Joint Tape for the meeting of a wall surface with the curved surface of an
Finishing Gypsum Board arch (see Fig. 1).
C 557 Specification for Adhesives for Fastening Gypsum base coat, n—the first layer or layers of plaster applied over a
Wallboard to Wood Framing lath or other substrate. The first application is normally
C 587 Specification for Gypsum Veneer Plaster called a scratch coat and the second application is referred to
C 588 Specification for Gypsum Base for Veneer Plasters as a brown coat.
E 84 Test Method for Surface Burning Characteristics of base coat floating, n—the finishing act of spreading, compact-
Building Materials ing, and smoothing of the base coat plaster to a reasonably
E 96 Test Methods for Water Vapor Transmission of Mate- true plane.
rials bedding coat, n—that coat of plaster to receive aggregate or
E 119 Test Methods for Fire Tests of Building Construction other decorative material of any size, impinged or embedded
and Materials into its surface, before it sets.
bond plaster, n—a calcined gypsum plaster specially formu-
lated for application over rough monolithic concrete as a
This terminology is under the jurisdiction of ASTM Committee C-11 on
bonding coat for a subsequent gypsum plaster layer
Gypsum and Related Building Materials and Systems and are the direct responsi-
bility of Subcommittee C11.91 on Terminology and Editorial. (C 28).
Current edition approved Oct. 10, 1998. Published March 1999. Originally
bridging, n—in framing, sections of wood or metal pieces
published as C 11 – 16 T. Last previous edition C 11 – 95a.
2 used between framing members to stiffen, give lateral
Annual Book of ASTM Standards, Vol 04.01.
Discontinued: See 1982 Annual Book of ASTM Standards, Vol 04.01.
Annual Book of ASTM Standards, Vol 04.07.
5 6
Annual Book of ASTM Standards, Vol 04.06. Annual Book of ASTM Standards, Vol 11.03.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
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cement plaster or stucco.
( 2) to maintain proper temperature and a sufficient quantity
of water within the plaster to ensure cement hydration.
dash-bond coat, n—a thick slurry of portland cement, sand,
and water, machine-sprayed or hand-dashed with a paddle or
stiff-bristled broom to any acceptable surface, to provide
improved adhesion and a key for the subsequent portland
cement plaster or stucco coat.
density, n—the weight per unit volume of a material
(C 472).
edge (of gypsum board), n—the paper-bound edge as manu-
factured.
embedding compound—see taping compound.
FIG. 1 Arris (of an Arch)
end (of gypsum board), n—the end perpendicular to the
support, and minimize rotation.
paper-bound edge. The gypsum core is always exposed.
brown coat, n—the second coat in three-coat gypsum plaster
expansion joint, n—see control (expansion-contraction)
application.
joint.
building construction joint, n—a designed division of a
face, n—the surface designed to be left exposed to view or to
building that allows movement of all component parts of the
receive decoration or additional finishes.
building, in any plane, which may be caused by thermal,
featured edge, n—an edge configuration of the paper bound
seismic, wind loading or any other force. The construction of
edge of gypsum board that provides special design or
the separation is accomplished by one of the following
performance.
methods: (1) manufactured devices suitable for this applica-
fineness modulus, n—an empirical factor obtained by adding
tion, or (2) by field fabrication of suitable materials.
total percentages of a sample of aggregate retained on each
calcined gypsum, n—a dry powder; primarily calcium sulfate
of a specified series of sieves and dividing by 100. The sieve
hemihydrate, resulting from calcination of gypsum; cemen-
sizes used are: No. 100 (150 μm), No. 50 (300 μm), No. 30
titious base for production of most gypsum plasters: also
(600 μm), No. 16 (1.18 mm), No. 8 (2.36 mm), No. 4 (4.75
3 3 1
called plaster of paris; sometimes called stucco.
mm), ⁄8 in. (9.5 mm), ⁄4 in. (19.0 mm), 1 ⁄2in. (38.1 mm) and
calcium sulfate, n—the chemical compound CaSO .
4 larger, increasing in the ratio of 2 to 1.
cementitious material, n—a material that, when mixed with
finish coat, n—the final layer of plaster applied over a basecoat
water, with or without aggregate, provides the plasticity and
or other substrate.
the cohesive and adhesive properties necessary for place-
finish coat floating, n—the finishing act of spreading, com-
ment, and the formation of a rigid mass.
pacting, and smoothing the finish coat plaster or stucco to a
combined water, n—the water chemically held, as water of
specified surface texture.
crystallization, by the calcium sulfate dihydrate or hemihy-
finishing compound, n—( sometimes called topping com-
drate crystal.
pound) a compound specifically formulated and manufac-
compressive strength, n—the maximum load sustained by a
tured for use over taping or all purpose compounds to
standard specimen of a material when subjected to a crush-
provide a smooth and level surface for the application of
ing force.
decoration.
consistency, n—a property of a material determined by the
fire-resistance classification, n— a standard rating of fire-
complete flow force relation (C 557).
resistance and protective characteristics of a building con-
consistency (normal), n—the number of millilitres of water
struction or assembly (E 119).
per 100 g of gypsum plaster or gypsum concrete required to
flame spread classification, n—a standard rating of relative
produce a mortar or a slurry of specified fluidity (C 472).
surface burning characteristics of a building material as
control (expansion-contraction) joint, n—a designed separa-
compared to a standard material (E 84).
tion in the system materials that allows for movement caused
flexural strength, n—the maximum load sustained by a
by expansion or contraction of the system. The construction
standard specimen of a sheet material when subjected to a
of the separation is accomplished by one of the following
bending force.
methods: (1) manufactured devices suitable for this applica-
framing member, n—stud, plate, track, joist, furring, and
tion, or (2) by field fabrication of suitable materials.
other support to which a gypsum panel product, or metal
core (of gypsum board), n—the hardened material filling the
plaster base is attached.
space between the face and back papers consisting substan-
free water, n—all water contained by gypsum board or plaster
tially of rehydrated gypsum with additives.
in excess of that chemically held as water of crystallization.
cored tile or block, n—see gypsum tile or block (C 52).
gauging plaster, n—a calcined gypsum plaster used with lime
corner reinforcement, exterior, n— a preformed section of
for a finish coat (C 28).
wire or expanded sheet steel, for the reinforcement of
grout, n—gypsum or portland cement plaster used to fill
exterior stucco external corners (arrises).
crevices or to fill hollow metal frames.
cure (portland cement plaster or stucco), v—(1) to provide
gypsum, n—the mineral consisting primarily of fully hydrated
conditions conducive to the hydration process of portland
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calcium sulfate, CaSO ·2H O or calcium sulfate dihydrate foil-backed gypsum wallboard—a gypsum wallboard with
4 2
(C 22). the back surface covered with a continuous sheet of pure
1 5
gypsum backing board, n—a ⁄4 in. to ⁄8 in. gypsum board for bright finished aluminum foil (C 36).
use as a backing for gypsum wallboard, acoustical tile, or type X gypsum wallboard—a gypsum wallboard specially
other dry cladding. manufactured to provide specific fire-resistant characteristics
water resistant gypsum backing board—a gypsum board (C 36).
designed for use on walls primarily as a base for the hemihydrate, n—the dry powder, calcium sulfate hemihy-
application of ceramic, or plastic
...