ASTM C961-06

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Designation:C961–06
Standard Test Method for
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Lap Shear Strength of Sealants
This standard is issued under the fixed designation C961; 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 shear stresses, and also provides information regarding the
adhesive bond to the substrates being tested.
1.1 This test method covers a laboratory procedure for
determining the lap shear strength of sealants. It also provides
6. Apparatus
information on the adhesive bond of the sealants to the tested
6.1 Sealant Applicator or Oven, capable of maintaining the
substrates.
sealant within 62.8°C (65°F) of the specified temperature.
1.2 The values stated in SI units are to be regarded as the
6.2 Substrates, of annealed glass that are 25.4 mm wide by
standard. The values given in parentheses are for information
76.2 mm long and 6.35 mm thick (1 by 3 by 0.25 in.). Other
only.
substrates may be used when specified (Fig. 1).
1.3 This standard does not purport to address all of the
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6.3 Template, to provide 3.18-mm ( ⁄8-in.) sealant thickness
safety concerns, if any, associated with its use. It is the
(Fig. 2).
responsibility of the user of this standard to establish appro-
6.4 Hot Knife or Spatula.
priate safety and health practices and determine the applica-
6.5 Tension Testing Machine, capable of pulling a specimen
bility of regulatory limitations prior to use.
at a rate of 12.7 mm (0.5 in.)/min.
1.4 The subcommittee with jurisdiction of this standard is
not aware of any similar or equivalent ISO standard.
7. Sampling
2. Referenced Documents 7.1 Sealant shall be free of external surface contaminants
such as talc, oil, dust, and moisture. Handling of the sealant
2.1 ASTM Standards:
surfaces in contact with the substrate shall be minimized.
C717 Terminology of Building Seals and Sealants
7.2 A 1.0-kg (2.2-lb) representative sample shall be taken
3. Terminology from bulk stock for testing.
3.1 Definitions:
8. Test Specimens
3.1.1 The definitions of the following terms used in this test
8.1 Prepare six test specimens from the bulk sample by
method are found in Terminology C717, 4.1: adhesive failure,
using the applicator or the oven method.
cohesive failure, sealant, and substrate.
8.1.1 Applicator Method:
4. Summary of Test Method 8.1.1.1 Clean the substrate surface with soap and water
followed by a water rinse and solvent wipe with methyl ethyl
4.1 The sealant is placed between two glass substrates. The
ketone (MEK).
sample is placed in a tensile tester and pulled at a constant rate
to failure. The maximum shear force and mode of failure is
NOTE 1—At the request of the sealant manufacturer, an alternative
noted. Maximum shear stress is calculated and reported. cleaning procedure may be used.
8.1.1.2 Using an appropriate die or nozzle, apply a 25.4 by
5. Significance and Use
25.4-mm (1 by 1-in.) layer of sealant onto one end of the
5.1 Sealants are generally subjected to longitudinal and
substrate surface at a thickness that when compressed will
lateral shear stresses in end use applications. This test method
comply with 8.1.1.4. Substrates shall be at a temperature of 23
measures the cohesive strength of sealants when subjected to
6 2°C, 50 6 10 % relative humidity (73.4 6 3.6°F).Apply the
sealant at the specified temperature 62.8°C (65°F) (Fig. 1).
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8.1.1.3 Immediately after sealant application place a second
ThistestmethodisunderthejurisdictionofASTMCommitteeC24onBuilding
2 2
Seals and Sealants and is the direct responsibility of Subcommittee C24.30 on
substrateontothesealanttoformanoverlapof6.45cm (1in. )
Adhesion.
(Fig. 1).
Current edition approved Sept. 1, 2006. Published September 2006. Originally
8.1.1.4 Using a template (Fig. 2), compress the overlayed
approved in 1981. Last previous edition approved in 2001 as C961 – 01. DOI:
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sealant to form the 3.18-mm ( ⁄8-in.) thick overlap (Fig. 3).
10.1520/C0961-06.
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C961–06
10.2 Visually inspect and record the mode of bond failure
(cohesiveoradhesive)andtheapproximatepercentageofeach.
10.3 Observe and record the maximum shear force in
newtons (or pounds-force).
11. Calculation
11.1 Calculate the maximum shear stress, S, as follows:
S 5 F/A
where:
2
S = maximum shear stress, Pa (or lbf/in. ),
F = maximum shear force, N (or lbf), and
2
A = contact area of the specimen with one substrate, m (or
2
in. ).
11.2 Average the results of the six specimens tested.
12. Report
12.1 Report the following informat
...