ASTM C793-02
(Test Method)Standard Test Method for Effects of Accelerated Weathering on Elastomeric Joint Sealants
Standard Test Method for Effects of Accelerated Weathering on Elastomeric Joint Sealants
SCOPE
1.1 This test method covers a laboratory procedure for determining the effects of accelerated weathering on cured-in-place elastomeric joint sealants (single- and multicomponent) for use in building construction.
1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.
1.3 The committee with jurisdiction over this standard is not aware of any comparable standards published by other ASTM committees or other organizations.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C 793 – 02
Standard Test Method for
Effects of Accelerated Weathering on Elastomeric Joint
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Sealants
This standard is issued under the fixed designation C 793; 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 of the cold exposure the specimens are bent over a mandrel
within1satthe specified temperature.
1.1 This test method covers a laboratory procedure for
determining the effects of accelerated weathering on cured-in-
5. Significance and Use
place elastomeric joint sealants (single- and multicomponent)
5.1 It is known that ultraviolet radiation contributes to the
for use in building construction.
degradation of sealants in exterior building joints. The use of a
1.2 The values stated in SI units are to be regarded as the
laboratory accelerated weathering machine with ultraviolet
standard. The values in parentheses are for information only.
radiation and intermittent water spray appears to be a feasible
1.3 The committee with jurisdiction over this standard is not
means to give indications of early degradation by the appear-
aware of any comparable standards published by other ASTM
ance of sealant cracking. However, other factors such as UV
committees or other organizations.
exposure in combination with extension may produce more
1.4 This standard does not purport to address all of the
severe degradation than UV alone. The effect of the test is
safety concerns, if any, associated with its use. It is the
made more sensitive by the addition of the bending of the
responsibility of the user of this standard to establish appro-
specimen at cold temperature.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
6. Apparatus
2. Referenced Documents 6.1 Exposure Apparatus—An accelerated weathering ma-
chine, twin-enclosed carbon arc with 102-18 light/water spray
2.1 ASTM Standards:
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cycle (102 min of light followed by 18 min of light and
C 717 Terminology of Building Seals and Sealants
deionized water). It shall conform to Type D of Practice G 23.
G 23 Practice for Operating Light-Exposure Apparatus
(Carbon-Arc Type) With and Without Water for Exposure
NOTE 1—There are several other weathering machines described in
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of Nonmetallic Materials Practice G 23 available for use, and these may or may not give different
results from the one described under Type D. Instruments that have a
3. Terminology means of humidification should operate without the humidifier.
3.1 Definitions—See Terminology C 717 for applicable
6.2 Freezer or Cold Box, having a temperature controlled
definitions of the following terms: cure, elastomeric, joint,
at −26 6 2°C (−15 6 3.6°F).
sealant, and substrate.
6.3 Rectangular Brass Frame, with inside dimensions 130
1 1
by 40 by3mm(5by1 ⁄2 by ⁄8 in.).
4. Summary of Test Method
6.4 Aluminum Plates, three, each 152 by 80 by 0.3 mm (6 by
4.1 Three sealant specimens are spread on aluminum plates
3 by 0.01 in.).
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and exposed to 250 h of ultraviolet radiation with intermittent
6.5 Steel Mandrel, 12.7 mm ( ⁄2 in.) in diameter and about
water spray in a standard accelerated weathering machine.
102 mm (4 in.) long.
Following this treatment the specimens are exposed for 24 h in
6.6 Thin-Bladed Knife.
a freezer maintained at −26 6 2°C (−15 6 3.6°F). At the end
6.7 Straightedge, metal or plastic, about 152 mm (6 in.)
long.
6.8 Spatula, steel, about 152 mm (6 in.) long.
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This test method is under the jurisdiction of ASTM Committee C24 on Building
Seals and Sealants and is the direct responsibility of Subcommittee C24.40 on
7. Standard Test Conditions
Weathering.
Current edition approved May 10, 2002. Published June 2002. Originally
7.1 Unless otherwise specified by those authorizing the test,
e1
published as C 793 – 75. Last previous edition C 793 – 91 (1997) .
standard conditions of temperature and relative humidity shall
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Annual Book of ASTM Standards, Vol 04.07.
be 23 6 2°C (73.4 6 3.6°F) and 50 6 5 %, respectively.
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Discontinued; see 1999 Annual Book of ASTM Standards, Vol 14.04.
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C793–02
frame until the sealant is sufficiently set that it will retain its rectangular
8. Procedure
shape.
8.1 Test of Multicomponent Sealants:
8.2 Test of Single-Component Sealants:
8.1.1 Condition at least 200 g of base compound and
8.2.1 Condition at least 200 g of compound in a closed
appropriate amount of curing agent and pigment, if required, in
container for at least 24
...
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