This video demonstrates the
proper procedures for
conducting a soil density test
by use of the Sand Cone
method, as well as the
procedures for the Microwave
method of drying soil.
The bulk density of the sand
is needed to compute the
volume of the hole made in the
embankment when running the
Sand Cone test.
This needs to be determined
prior to using the test sand
in the field.
At the same time, it is
imperative that the cone
correction factor is
also determined.
The cone correction factor is
the amount of sand it takes to
fill the cone of the testing
apparatus, plus it includes
the space between the
base plate and the
surface of the test.
The weight of the removed soil,
along with the bulk
density, are used to determine
the volume of the test hole.
The volume of the test
hole is used to
determine the dry density.
Place the empty apparatus
upright on
a firm, level surface.
Close the valve and fill
the funnel with sand.
Open the valve and keep the
funnel at least half full with
sand during filling.
When the sand stops flowing into
the apparatus, close the
valve sharply and empty
the excess sand.
Determine and record
the weight of the
apparatus filled with sand.
The Sand Cone test procedure is
to dig a test hole, place
the Sand Cone over the hole and
fill the hole with sand.
Once a test site has been
selected, make sure it is
level and free from
loose material.
Place the base plate over the
smooth area and securely
fasten it down with the
pins included in
the compaction kit.
The next step is to dig a hole
to a depth of approximately
four to five inches deep and
to the same diameter as the
hole in the base plate.
This depth should provide a
proper volume based on the
maximum particle size.
Caution should be taken when
removing the soil from the
test hole, so that none of
the material is lost.
A fine brush is used to remove
soil particles that may be
clinging to the auger, spoon,
or on the base plate.
As you are digging the hole,
put the material retrieved
from the hole into
a non-absorbent
moisture-tight container.
Make sure the container
has a lid that
can be securely tightened.
Once all the material has been
removed, seal the container to
prevent loss of moisture.
All of the soil, including any
loose soil at the bottom of
the hole, should be placed
in the container.
Great care must be taken to get
the walls of the hole as
smooth as possible as this
affects the volume
measurement.
Shape the bottom and sides of
the test hole with the spoon
used in removing the soil.
When the test hole is ready,
with the valve closed, invert
the cone with the sand filled
jar in the center hole of the
base plate.
Open the valve so that sand
flows down into the test hole.
This part of the test should be
done in such a way that the
Sand Cone is free from any
vibrations or disturbances
during the flowing
of the sand.
Vibrations can affect the bulk
density of the sand and
decrease the accuracy
of the test.
Once the sand flow stops, close
the valve and remove the
sand cone apparatus.
Next, weigh the container filled
with the soil removed
from the test hole.
Record this weight.
Now weigh the Sand Cone
apparatus and record.
The difference between the
initial weight of the Sand
Cone apparatus and the final
weight are used in the
calculations to determine the
weight of the sand needed to
fill the hole.
A previously determined cone
calibration factor is also
used to calculate the
weight of the sand
needed to fill the hole.
The weights are used
to determine the
volume of the test hole.
The volume of the test
hole is used to
determine the dry density.
The next step demonstrated in
this video is the procedure
used to determine the moisture
content of the soil by use of
the microwave method
of drying soil.
Take between 300 to 500 grams
of the soil sample
taken from the hole.
Place the sample in a
microwave-safe container that
has a known tare weight.
Weigh and record.
As shown in this video, the
Microwave method of drying
soil is being run in the field
at the test location.
The microwave is being
powered with the use
of a portable generator.
Place the soil sample in the
microwave oven and run the
microwave for three minutes
using the defrost setting.
Remove the sample and stir it.
Return it to the oven.
Continue with one minute cycles
of drying and stirring
the sample.
Weigh the sample after
each interval.
Stirring the sample aids
in uniform drying.
Stirring also helps you see when
the sample is dry, since
generally dry soil particles
will not stick to a spoon.
Continue drying until a constant
weight is achieved.
The time needed to achieve
constant weight will vary
depending on the type
of soil, sample
size, and the microwave.
Complete the final calculations
using the
appropriate worksheet.
