FIG. 3 Permeability Test Data Sheet D 2434 – 68 (2006) 4
permeameter cylinder, making an air-tight seal. This satisfies
the condition described in
of holding the initial density
without significant volume change during the test.
6.6.4 Using a vacuum pump or suitable aspirator, evacuate
the specimen under 50 cm (20 in.) Hg minimum for 15 min to
remove air adhering to soil particles and from the voids.
Follow the evacuation by a slow saturation of the specimen
from the bottom upward (
) under full vacuum in order to
free any remaining air in the specimen. Continued saturation of
the specimen can be maintained more adequately by the use of
( 1) de-aired water, or (2) water maintained in an in-flow
temperature sufficiently high to cause a decreasing temperature
gradient in the specimen during the test. Native water or water
of low mineral content (
) should be used for the test, but
in any case the fluid should be described on the report form
). This satisfies the condition described in
saturation of soil voids.
4—Native water is the water occurring in the rock or soil in situ.
It should be used if possible, but it (as well as de-aired water) may be a
refinement not ordinarily feasible for large-scale production testing.
6.6.5 After the specimen has been saturated and the per-
meameter is full of water, close the bottom valve on the outlet
) and disconnect the vacuum. Care should be taken
to ensure that the permeability flow system and the manometer
system are free of air and are working satisfactorily. Fill the
inlet tube with water from the constant-head tank by slightly
opening the filter tank valve. Then connect the inlet tube to the
top of the permeameter, open the inlet valve slightly and open
the manometer outlet cocks slightly, to allow water to flow,
thus freeing them of air. Connect the water manometer tubes to
the manometer outlets and fill with water to remove the air.
Close the inlet valve and open the outlet valve to allow the
water in the manometer tubes to reach their stable water level
under zero head.