ASTM C792-04

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Designation:C792–04
Standard Test Method for
Effects of Heat Aging on Weight Loss, Cracking, and
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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 5. Significance and Use
1.1 This test method covers a laboratory procedure for 5.1 Weight loss through volatilization of components of a
determining the effects of heat aging on weight loss, cracking, sealant in a building joint may affect sealant appearance
and chalking of cured-in-place elastomeric joint sealants because of shrinkage and sealant performance because of the
(single- and multicomponent) for use in building construction. loss of functional sealant components. Exposure to high-
1.2 This standard does not purport to address all of the temperature environments will accelerate the loss of volatiles.
safety problems, if any, associated with its use. It is the 5.2 This test method measures weight loss. It can be used in
responsibility of the user of this standard to establish appro- combination with a knowledge of sealant density to estimate
priate safety and health practices and determine the applica- shrinkage. In addition, when compared to sealant theoretical
bility of regulatory limitations prior to use. weight solids, it provides an estimate of the extent to which
1.3 There is no known ISO equivalent to this test method. functionalsealantcomponentscanbevolatilizedwhenexposed
to high service temperatures. Substantial losses of this type
2. Referenced Documents
may help predict early failures in durability.Also, development
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2.1 ASTM Standards: of cracks or chalking, or both, lessens sealant service life.
C 717 Terminology of Building Seals and Sealants
However, a sealant that develops no cracks or chalking, or low
weight loss in this test method, does not necessarily assure
3. Terminology
good durability.
3.1 Definitions—See Terminology C 717 for definitions of
6. Apparatus
the following terms used in this test method: compound,
elastomeric, non-sag sealant, sealant, and self-leveling sealant. 6.1 Forced-Draft Oven, controlled at 70 6 2°C (158 6
3.6°F).
4. Summary of Test Method
6.2 Balance, sensitive to 0.01 g.
4.1 Three sealant specimens are spread on thin aluminum
6.3 Rectangular Brass Frame, with inside dimensions 130
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plates and, after determining net weights of sealant, are cured
by 40 by 6.4 mm (5 by 1 ⁄2 by ⁄4 in.).
for 7 days at 23 6 2°C (74 6 3.6°F) and 50 6 5 % relative
6.4 Aluminum Plates, three, each 152 by 80 by 0.6 to 1.6
humidity. Immediately following this initial cure time two
mm (24 to 16 gage).
specimens are exposed in a forced-draft oven maintained at 70
6.5 Straightedge, metal or plastic, about 152 mm (6 in.)
6 2°C (1586 3.6°F) for 21 days. At the end of this exposure
long.
the percentage weight loss of the sealant is determined and
6.6 Thin Knife Blade.
examination is made for presence of cracks and chalking.
6.7 Spatula, steel, about 152 mm (6 in.) long.
7. Procedure
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This test method is under the jurisdiction of ASTM Committee C-24 on
7.1 Unless otherwise specified by those authorizing the test,
Building Seals and Sealants and is the direct responsibility of Subcommittee C24.20
standard conditions of temperature and relative humidity for
on General Test Methods.
Current edition approved Dec. 1, 2004. Published January 2005. Originally the test shall be 23 6 2°C, (73 6 3.6°F) and 50 6 5%,
approved in 1975. Last previous edition approved in 1998 as C 792 – 93 (1998).
respectively.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
7.2 Test of Multicomponent Sealants:
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
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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C792–04
7.2.1 Condition at least 400 g of base compound and 7.3.1 Condition at least 400 g of compound in a closed
appropriate amount of curing agent in a closed container for at container for at least 24 h at standard conditions.
least 24 h at standard conditions; then mix thoroughly for 5 7.3.2 Follow the same procedure as specified in 7.2.1-7.2.6,
min. eliminating the mixing necessary for multicomponent sealants.
7.2.2 Weigh the three aluminum plates to the nearest 0.01 g.
8. Report
7.2.3 Fill the rectangular
...