SHRP-A-379 traducir

7.2.5 Since the specimen will be subjected to confining pressure with compressed air
during the test, confirm that the system is not leaking before starting the test. Thoroughly
check the membrane and all connecting hoses and fittings, and replace or tighten as
necessary.
NOTE8.--Vacuumcanbe usedto checkfor defectiveconnectionsor a faultymembranewhichmaycause
Ieakage.Twohosesconnectthe platensto the outsideof the confiningcellandto the atmosphere.Thesehoses
preventthe buildupof air pressurebetweenthe specimenandthe membrane,andserveto warnof anyleaksin the
membraneor the sealsbetweenthe membraneandtheplatens.
7.2.6 Place the completed specimen test assembly into the testing cell in the shear
test device. Confn'm that the specimen is in the center of the cell and not in contact with the
surrounding walls, and that the radial LVDT can move freely around the specimen without
any interference from other objects.
7.2.7 Lower the confining cell and lock in place. Bring the specimen assembly to the
required test temperature and allow sufficient time for the temperature to stabilize.
7.2.8 Open the air pressure valve to begin the test. Precondition the specimen by
rapidly applying, then removing hydrostatic pressure. Ramp the pressure to 70 kPa in one
second and immediately reduce it to 7 kPa.
7.2.9 Conduct the volurnetric test by increasing the hydrostatic pressure at a rate of
70 kPa/s to: 550 kPa at 40°C, 690 kPa at 20°C, or 830 kPa at 4°C. Maintain the pressure at
that Ievel for 10 seconds and then reduce it to 7 kPa at a rate of 25 kPa/s. Hold the specimen
at this pressure
for an additional 30 seconds.
7.2.10 Record the axial deformation on both sides of the specimen, the radial
deformation, and the hydrostatic pressure at a rate of about 10 data points per second.
NOTE9.--The volumetrictesttakesabout30 minutesto complete.Thisincludesset-up,placingof the
specimenin the cell, runningthe test, andremovingthe specimenfromthe apparatus.
7.3 Uniaxial Strain Test
7.3.1 Place the specimen (prepared in accordance with sections 6.1 and 6.2) between
the top and bottom platens.
thick,
7.3.2 Surround the specimen with a membrane, 150 mm in diameter and 0.6 mm
that is open at both ends and free of any defects.
7.3.3 Fix the membrane tightly to the platens with rubber O-rings.
7.3.4 Mount a radial LVDT around the circumference of the specimen to measure its
radial deformation. Then mount LVDTs on both sides of the specimen to measure axial
deformation
from platen to platen.
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