7. Procedure
7.1 Place the specimen in the loading device so that it is
centered on the bottom platen. Adjust the loading device
carefully so that the upper platen just makes contact with the
specimen. Zero the deformation indicator. Apply the load so as
to produce an axial strain at a rate of
1
⁄
2
to 2 %/min. Record
load, deformation, and time values at sufficient intervals to
define the shape of the stress-strain curve (usually 10 to 15
points are sufficient). The rate of strain should be chosen so that
the time to failure does not exceed about 15 min (Note 7).
Continue loading until the load values decrease with increasing
strain, or until 15 % strain is reached. The rate of strain used for
testing sealed specimens may be decreased if deemed desirable
for better test results. Indicate the rate of strain in the report of
the test data, as required in 9.1.7. Determine the water content
of the test specimen using the entire specimen, unless repre-
sentative trimmings are obtained for this purpose, as in the case
of undisturbed specimens. Indicate on the test report whether
the water content sample was obtained before or after the shear
test, as required in 9.1.2.
N
OTE
7—Softer materials that will exhibit larger deformation at failure
should be tested at a higher rate of strain. Conversely, stiff or brittle
materials that will exhibit small deformations at failure should be tested at
a lower rate of strain.
7.2 Make a sketch, or take a photo, of the test specimen at
failure showing the slope angle of the failure surface if the
angle is measurable.
7.3 A copy of a example data sheet is included in Appendix
X1. Any data sheet can be used, provided the form contains all
the required data.
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