ASTM C631-95a(2004)

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Designation: C 631 – 95a (Reapproved 2004)
Standard Specification for
Bonding Compounds for Interior Gypsum Plastering
This standard is issued under the fixed designation C631; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope suitable for application by brush, roller, and spray. The
compound shall be tinted to show, by visual inspection, where
1.1 This specification covers minimum requirements for
ithasbeenapplied.Thetintingmaterialshallnotshowthrough
bonding compounds for adhering interior gypsum plaster to
the material being bonded. The surfaces to which bonding
structurally sound surfaces.
compounds are applied shall be relatively smooth, clean, and
1.2 Thisspecificationalsocoverstestmethodsfordetermin-
dry. Surface coatings shall be removed if their nature indicates
ing performance requirements and physical properties.
an unsatisfactory condition. Surfaces shall be prepared in
1.3 The values stated in inch-pound units are to be regarded
accordance with the manufacturer’s directions.
as the standard. The SI equivalents of inch-pound units are
4.2 Consistency—The bonding compound shall be of a
approximate.
homogeneous nature with no settling of the solids. The
1.4 The following safety hazards caveat pertains only to the
compound shall be free of foreign matter, and when applied in
testmethodsdescribedinthisspecification: This standard does
accordance with the manufacturer’s directions, shall cover
not purport to address all of the safety concerns, if any,
evenly.
associated with its use. It is the responsibility of the user of this
4.3 Film Characteristics—A dry film of the bonding com-
standard to establish appropriate safety and health practices
pound shall be uniform and smooth and shall remain flexible.
and determine the applicability of regulatory limitations prior
Thefilmshallnotbenoticeablyaffectedbymildacidoralkali.
to use.
5. Performance Requirements
2. Referenced Documents
5.1 Bonding Capability—A dry film of bonding compound
2.1 ASTM Standards:
shall be capable of bonding gypsum plaster immediately after
C11 Terminology Relating to Gypsum and Related Build-
drying and 10 days after drying when tested as specified in
ing Materials and Systems
Section 12.
C28 Specification for Gypsum Plasters
5.2 Degradation—Bonding compound that separates shall
C472 Test Methods for Physical Testing of Gypsum, Gyp-
beabletobere-mixedtoauniformconsistencywhentestedas
sum Plasters, and Gypsum Concrete
specified in Section 10.
C511 Specification for Mixing Rooms, Moist Cabinets,
5.3 High Temperature Stability—Thebondstrengthshallbe
Moist Rooms, and Water Storage Tanks Used in the
not less than 20 psi (138 kPa) when tested as specified in
Testing of Hydraulic Cements and Concretes
Section 9.
3. Terminology
5.4 Freeze-Thaw Stability—The bond strength shall be not
less than 20 psi (138 kPa) when tested as specified in Section
3.1 Definitions—For definitions relating to gypsum and
11.
related building materials and systems, see Terminology C11.
5.5 Bond Strength—Bondstrengthofafreshsampleora30
4. Physical Properties
day old sample shall be not less than 20 psi (138 kPa) when
tested as specified in Section 12.
4.1 General—The bonding compound shall be a film form-
ing, non-oxidizing, non-toxic, non-flammable composition
6. Sampling
6.1 Take a sample of not less than 1 kg from each shipment
This specification is under the jurisdiction of ASTM Committee C11 on
or consignment for analysis and tests. Except in special cases,
GypsumandRelatedBuildingMaterialsandSystemsandisthedirectresponsibility
take the sample from not less than three separate containers,
of Subcommittee C11.02 on Specifications and Test Methods for Accessories and
chosen at random. In addition, take samples from containers
Related Products.
Current edition approved Oct. 10, 1995. Published December 1995. Originally
that appear to be nonrepresentative, and test separately. Imme-
approved in 1988. Last previous edition approved in 1995 as C 631–95.
diately place the samples in airtight glass containers and
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
transport to the testing laboratory in these containers. Take
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on precautions to reduce evaporation or drying to a minimum.
the ASTM website.
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C 631 – 95a (2004)
Thoroughly mix the bonding compound in the container if
there is a tendency for liquid phase separation.
7. Apparatus
7.1 Moist Cabinet—Specification C511.
7.2 Oven—A forced draft type oven, having a temperature
controlledat140 65°F(60 63°C)forhightemperaturetests
and 100 65°F(38 6 3 °C) for drying of the briquets.
7.3 Freezer—A freezer having a controlled temperature
of−10 6 2 °F (-23 6 1 °C).
7.4 Balance—Abalancecapableofweighingatleast2500g
at a precision of 0.1 g.
7.5 Timing Device—Astandard clock or watch with second
hand.
7.6 Tamper—A tamper made up of a nonabsorptive, non-
abrasive, non-brittle material and having a cross section of ⁄2
in. by 1 in. (13 by 25 mm) and approximately 5 to 6 in. (130
to 150 mm) long. The tamping face shall be flat and at right
angles to the length of the tamper.
7.7 Straight Edge—Asteel straight edge not less than 4 in.
(100mm)longandnotlessthan ⁄16in.(1.6mm)normorethan
⁄8 in. (3.2 mm) in thickness.
7.8 Spatula—Aspatulawithametalblade6in.(150mm)in
length and ⁄2 in. (13 mm) in width, with straight edges.
7.9 Paint Brush—A standard 1 in. (25 mm) wide brush,
with natural or synthetic bristles.
7.10 Testing Machine—Any type that is of sufficient capac-
ity and that is capable of applying the load continuously and
without shock at the rate of 0.05 in. (1.27 mm)/min, with
NOTE 1—1 in.=25.4 mm
provision for adjustment of the rate of loading.
FIG. 2 Briquet Specimen for Tensile Strength Test
7.11 Briquet Molds—The molds for making test specimens
shall be made of metal not attacked by the plaster mortar and
7.13 Clips for Briquet Testing Machine— The clips for
shall have sufficient material in the sides to prevent spreading
holding the tension test specimen shall be in accordance with
during molding. Gang molds, when used, shall be of the type
Fig. 3.
shown in Fig. 1. The dimensions of the briquet molds shall
8. Conditioning
conform to the following requirements: width of mold, be-
tween inside faces, at waist line of the briquet, 1 in. (25.4 mm)
8.1 Room Temperature and Humidity— Maintain the air
with permissible variations of 60.01 in. (0.25 mm) for molds
temperatureinthevicinityofthemixingandtestingarea,70 6
in use and 60.005 in. (0.13 mm) for new molds; thickness of
5°F(21 6 3 °C). Maintain the relative humidity at 50 62%.
moldsmeasuredatthepointofgreatestthicknessoneitherside
8.2 Temperature of the Mixing Water—72 62°F(22 6 1
of the mold at the waist line, 1 in. (25.4 mm) with permissible
°C).
variations of+0.004 in. (0.10 mm) and−0.002 in. (0.05 mm)
9. High Temperature Test
for new molds and−0.02 in. (0.5 mm) for molds in use. The
inside faces at the waist line shall have a vertical slot 0.03 in. 9.1 Significance and Use—This test method provides pro-
(0.75 mm) wide by 0.06 in. (1.5 mm) deep to accept the cedures for evaluating the bond strength of adhesives after
divider. The briquet specimens shall conform to the dimen- being exposed to accelerated aging at high temperature.
sional requirements shown in Fig. 2. 9.2 Specimen Preparation—Foreachtestspecimen,transfer
7.12 Divider—Sheet brass 0.02 in. (0.05 mm) thick, 1.1 in. the bonding compound, taken from the sample obtained, into a
(27.8 mm) wide by 1 in. (25.4 mm) high. standard 1 pt (400 mL) glass container.
FIG. 1 Briquet Gang Mold
C 631 – 95a (2004)
NOTE 1—1 in.=25.4 mm
FIG. 3 Clips for Briquet Testing Machine
9.3 Procedure—Placethespecimenintheovenfor30days. 10.4 Tests and Retests—Bonding compound that fails to be
Remove the container, allow the compound to cool to room remixed to a uniform consistency shall be considered to have
temperature, mix the compound to a uniform consistency, and failed the test.
test as specified in Section 12. 10.5 Report—Determine the extent of settling and separa-
9.4 Test and Retests—Test six briquets and report the tion by measuring, and report as a percentage of the height of
average of the test results. If the result of any one of the six the specimen in the clear glass container, represented by the
tests varied more than 15% from the average, reject it and location of the liquid/solid interface.
report the average of the other five te
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