ASTM C792-93(1998)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:C792–93 (Reapproved 1998)
Standard Test Method for
Effects of Heat Aging on Weight Loss, Cracking, and
Chalking of Elastomeric Sealants
This standard is issued under the fixed designation C 792; 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 loss of functional sealant components. Exposure to high-
temperature environments will accelerate the loss of volatiles.
1.1 This test method covers a laboratory procedure for
5.2 This test method measures weight loss. It can be used in
determining the effects of heat aging on weight loss, cracking,
combination with a knowledge of sealant density to estimate
and chalking of cured-in-place elastomeric joint sealants
shrinkage. In addition, when compared to sealant theoretical
(single- and multicomponent) for use in building construction.
weight solids, it provides an estimate of the extent to which
1.2 This standard does not purport to address all of the
functionalsealantcomponentscanbevolatilizedwhenexposed
safety problems, if any, associated with its use. It is the
to high service temperatures. Substantial losses of this type
responsibility of the user of this standard to establish appro-
may help predict early failures in durability.Also, development
priate safety and health practices and determine the applica-
of cracks or chalking, or both, lessens sealant service life.
bility of regulatory limitations prior to use.
However, a sealant that develops no cracks or chalking, or low
2. Referenced Documents weight loss in this test method, does not necessarily assure
good durability.
2.1 ASTM Standards:
C 717 Terminology of Building Seals and Sealants
6. Apparatus
3. Terminology
6.1 Forced-Draft Oven, controlled at 70 6 2°C (158 6
3.6°F).
3.1 Definitions—See Terminology C 717 for definitions of
6.2 Balance, sensitive to 0.01 g.
the following terms used in this test method: compound,
6.3 Rectangular Brass Frame, with inside dimensions 130
elastomeric, non-sag sealant, sealant, and self-leveling sealant.
1 1
by 40 by 6.4 mm (5 by 1 ⁄2 by ⁄4 in.).
4. Summary of Test Method
6.4 Aluminum Plates, three, each 152 by 80 by 0.6 to 1.6
mm (24 to 16 gage).
4.1 Three sealant specimens are spread on thin aluminum
6.5 Straightedge, metal or plastic, about 152 mm (6 in.)
plates and, after determining net weights of sealant, are cured
long.
for 7 days at 23 6 2°C (74 6 3.6°F) and 50 6 5 % relative
6.6 Thin Knife Blade.
humidity. Immediately following this initial cure time two
6.7 Spatula, steel, about 152 mm (6 in.) long.
specimens are exposed in a forced-draft oven maintained at 70
6 2°C (1586 3.6°F) for 21 days. At the end of this exposure
7. Procedure
the percentage weight loss of the sealant is determined and
7.1 Unless otherwise specified by those authorizing the test,
examination is made for presence of cracks and chalking.
standard conditions of temperature and relative humidity for
5. Significance and Use
the test shall be 23 6 2°C, (73 6 3.6°F) and 50 6 5%,
respectively.
5.1 Weight loss through volatilization of components of a
7.2 Test of Multicomponent Sealants:
sealant in a building joint may affect sealant appearance
7.2.1 Condition at least 400 g of base compound and
because of shrinkage and sealant performance because of the
appropriate amount of curing agent in a closed container for at
least 24 h at standard conditions; then mix thoroughly for 5
min.
This test method is under the jurisdiction of ASTM Committee C-24 on
Building Seals and Sealants and is the direct responsibility of Subcommittee C24.20
7.2.2 Weigh the three aluminum plates to the nearest 0.01 g.
on General Test Methods.
7.2.3 Fill the rectangular frame, after centering it on an
Current edition approved April 15, 1993. Published June 1993. Originally
aluminum plate, with a portion of the conditioned compound,
published as C 792 – 75. Last previous edition C 792 – 75 (1987).
Annual Book of ASTM Standards, Vol 04.07. and strike it off flat with a straightedge. Immediately lift the
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