ASTM C1681-23

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Designation: C1681 − 18 C1681 − 23
Standard Test Method for
Evaluating the Tear Resistance of a Sealant Under Constant
Strain
This standard is issued under the fixed designation C1681; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method evaluates the impact of an induced tear on a sealant specimen that is dimensioned, cured according to the
guidelines in Test Method C719 and then subjected to a constant strain. It is effective in differentiating between sealants that are
used in dynamic joints subject to abrasion, punctures, tears, or combination thereof.
1.2 Since this test method is for the evaluation of tear propagation, an adhesive failure to the substrates provides no usable data
regarding tear propagation. This would be considered a failed test and that data would be discarded, or at least separated from the
other data from specimens that did not experience an adhesive failure.
1.3 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 The committee with jurisdiction over this standard is not aware of any comparable standards published by other organizations.
This standard is similar in concept to European Technical Approval Guidelines (ETAG) 002, Part 1, Section 5.1.4.6.4—Resistance
To Tearing.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C717 Terminology of Building Seals and Sealants
C719 Test Method for Adhesion and Cohesion of Elastomeric Joint Sealants Under Cyclic Movement (Hockman Cycle)
3. Terminology
3.1 Definitions—Refer to Terminology C717 for definitions of terms used in this standard, including but not limited to the
following: adhesive failure, casting spacers, cohesive failure, separators, standard conditions.
This test method is under the jurisdiction of ASTM Committee C24 on Building Seals and Sealants and is the direct responsibility of Subcommittee C24.20 on General
Test Methods.
Current edition approved Jan. 1, 2018June 1, 2023. Published January 2018July 2023. Originally approved in 2009. Last previous edition approved in 20142018 as
C1681C1681 – 18.-14. DOI: 10.1520/C1681-18.10.1520/C1681-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 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.
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C1681 − 23
4. Summary of Test Method
4.1 Test specimens are fabricated and cured in accordance with Test Method C719. At the end of the 21-day cure period, an
induced tear is created in the specimens by making a cut with a sharp blade in the midpoint of the joint. The specimens are then
extended to a specified strain at both standard conditions and at –26 6 2°C (–15 6 3°F).–26 °C 6 2 °C (–15 °F 6 3 °F).
Propagation of the induced tear is measured at 0, 24, and 168 h.
5. Significance and Use
5.1 This test method is intended to determine if a joint that is subjected to a mechanically induced cut will resist tear propagation
during normal joint movement. A sealant with a high resistance to tear propagation will typically perform better than a sealant with
a low resistance to tear propagation.
NOTE 1—A sealant with a high resistance to tear propagation may perform better than a sealant with a low resistance to tear propagation.
6. Apparatus and Materials
6.1 A device capable of extending the test specimens to the specified strain.
6.2 Freezer, to maintain a constant temperature of –26°C 6 2°C.
6.3 A suitable measuring device such as calipers able to measure the induced tears to 0.01 mm.
6.4 #17 Knife Blade, 9 mm (0.375 in.) wide.
6.5 Spatulas, for use in applying the sealant.
6.6 Caulking Gun, for extruding sealant from cartridges when applicable.
6.7 Substrates, twelve substrates, with minimum dimensions of 25.4 mm by 76.2 mm (1 by 3 in.) of the same finish are required
for each product to be tested. Glass is the default substrate, however as mentioned in the scope, this is not an adhesion test,
therefore the sealant must exhibit excellent adhesion to the substrate. Other rigid substrates in the above noted dimension are
acceptable. Substrate blocks or plates should be of adequate thickness or reinforced such that they do not flex or break during the
testing.
6.8 Casting Spacers, provide joint dimensions of 12.7 mm by 12.7 mm by 50.8 mm (0.5 by 0.5 by 2 in.). See Fig. 5 in Test Method
C719.
6.9 Separators, to provide a constant strain on the specimen while maintaining parallel bond surfaces.
6.10 Substrate Cleaning Material.
6.11 Primer, if required on the substrates.
6.12 A suitable measuring device, such as calipers, capable of measuring the induced cut in the sealant and additional changes,
if any, in the cut to 0.01 mm.
6.13 Marker, to identify the exact placement of the induced cut.
6.14 A device which holds a #17 knife blade 9 mm (0.375 in.) wide to induce the cut into the test specimens. See Fig. 1.
7. Reagents and Materials
7.1 Spatulas, for use in applying the sealant.
C1681 − 23
FIG. 1 #17 Blade
7.2 Caulking Gun, for extruding sealant from cartridges when applicable.
7.3 Substrates—twelve substrates, with minimum dimensions of 25 by 75 mm (1 by 3 in.) of the same finish are required for each
product to be tested. Glass is the default substrate, however as mentioned in the scope, this is not an adhesion test, therefore the
sealant must exhibit excellent adhesion to the substrate. Other rigid substrates in the above noted dimension are acceptable.
Substrate blocks or plates should be of adequate thickness or reinforced such that they do not flex or break during the testing.
7.4 Casting Spacers—The casting spacers provide joint dimensions of 12.7 by 12.7 by 50.8 mm (0.5 by 0.5 by 2 in.). See Fig.
5 in Test Method C719.
7.5 Separators, to provide a constant strain on the specimen while maintaining parallel bond surfaces.
7.6 Substrate Cleaning Material.
7.7 Primer, if required on the substrates.
7.8 A suitable measuring device, such as calipers, capable of measuring the induced cut in the sealant and additional changes in
the cut to 0.01 mm.
7.9 Marker, to identify the exact placement of the induced cut.
7.10 A device which holds a #17 knife blade 9 mm (0.375 in.) wide to induce the cut into the test specimens. See Fig. 1.
7. Conditioning
7.1 Multicomponent Sealants—Prepare six test specimens for each type of substrate that is to be used in the test. After maintaining
the unopened sample for at least 24 h at standard conditions, mix thoroughly for 5 min at least 250 g 250 g of base compound with
the appropriate amount of curing agent. Extrude the sealant 12.7 by 12.7 by 50.8 mm 12.7 mm by 12.7 mm by 50.8 mm (0.5 by
0.5 by 2 in.) 2 in.) between parallel 25.4 by 76.2 mm (1 by 3 in.) 25.4 mm by 76.2 mm (1 by 3 in.) surfaces of similar blocks or
plates of the selected substrate. Use the appropriate casting spacers to form the proper size of the bead. Use adhesive tape, rubber
bands, or clamps to hold the test assembly together before and after filling it with the compound. In the case of a pourable-type
compound, use masking or any other suitable tape to retain the compound.
C1681 − 23
7.2 Clean the test substrates using the methods suggested in Test Method C719. Fabricate the joints using the casting spacers.
Mask off the top of the substrate edges, extrude the test sealant into the cavity taking care to fill in the all of the corners, tool the
top surface flat, and remove the masking tape.
7.3 Single-Component Sealants—Prepare six test specimens as described in 8.17.1 except that no mixing of components is
required. Condition the sealed cartridge or bulk container at standard conditions at least 24 h before use.
7.4 Cure specimens made with multicomponent sealants for 14 days at standard conditions. During the second week of the curing
period, free the compound from the casting spacers at the ends and bottom without damaging the sealant bead. Reference Test
Method C719 for information on how to proceed if specimens are damaged during casting spacer removal.
7.5 Cure specimens made with single-component sealants for a total of 21 days at standard conditions. See 8.6.17.6.1.
7.6 Separate the casting spacers from the sealant as soon as practical during the curing period without damaging the sealant.
Fourteen days is typically necessary. Reference Test Method C719 for information on
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