Geology Reference
In-Depth Information
contact with the lower porous plate or screen, or previously formed
layer, and fill the funnel with sufficient soil to form a layer, taking
soil from different areas of the sample in the pan. Lift the funnel by
15 mm (0.60 in.), or approximately the unconsolidated layer thick-
ness to be formed, and spread the soil with a slow spiral motion,
working from the perimeter of the device toward the center, so that
a uniform layer is formed. Remix the soil in the pan for each succes-
sive layer to reduce segregation caused by taking soil from the pan.
(4.2) For soils with a maximum size greater than 9.5 mm (
3
⁄
8
in.),
spread the soil from a scoop. Uniform spreading can be obtained by
sliding a scoopful of soil in a nearly horizontal position down along
the inside surface of the device to the bottom or to the formed layer,
then tilting the scoop and drawing it toward the center with a sin-
gle slow motion; this allows the soil to run smoothly from the scoop
in a windrow without segregation. Turn the permeability cylinder
sufficiently for the next scoopful, thus progressing around the in-
side perimeter to form a uniform compacted layer of a thickness
equal to the maximum particle size.
(5) Compact successive layers of soil to the desired relative den-
sity by appropriate procedures, as follows, to a height of about 2 cm
(0.8 in.) above the upper manometer outlet.
(5.1)
Minimum Density (0% Relative Density)
—Continue placing
layers of soil in succession by one of the procedures described in
(4.1) or (4.2) until the device is filled to the proper level.
(5.2)
Maximum Density (100% Relative Density):
(5.2.1)
Compaction by Vibrating Tamper
—Compact each layer of
soil thoroughly with the vibrating tamper, distributing the light
tamping action uniformly over the surface of the layer in a regular
pattern. The pressure of contact and the length of time of the
vibrating action at each spot should not cause soil to escape from
beneath the edges of the tamping foot, thus tending to loosen the
layer. Make a sufficient number of coverages to produce maximum
density, as evidenced by practically no visible motion of surface
particles adjacent to the edges of the tamping foot.
(5.2.2)
Compaction by Sliding Weight Tamper
—Compact each
layer of soil thoroughly by tamping blows uniformly distributed
over the surface of the layer. Adjust the height of drop and give suf-
ficient coverages to produce maximum density, depending on the
coarseness and gravel content of the soil.
(5.2.3)
Compaction by Other Methods
—Compaction may be accom-
plished by other approved methods, such as by vibratory packer
equipment, where care is taken to obtain a uniform specimen with-
out segregation of particle sizes.
(5.3)
Relative Density Intermediate between 0 and 100%
—By trial
in a separate container of the same diameter as the permeability
cylinder, adjust the compaction to obtain reproducible values of
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