Lesson 4/Learning Event 3
Open the valve carefully and permit the sand to fill the space under the cone.
Close the valve and weigh the apparatus and remaining sand. Record this weight (line 8, Figure
19). The difference in weight between the starting and final values (lines 7 and 8) is the weight
of sand in the tray and cone (line 9).
After making the calibration, recover as much of the sand from the tray as feasible without
disturbing the tray or the soil in the hole. Brush the remaining sand particles lightly from within
the tray.
Digging the Sample. The next procedure is to dig into the soil through the center hole in the tray. A
hole is required which is about six inches deep and approximately the same diameter as the hole in the
tray. The digging of samples in nonplastic coarse-grained soils is difficult, especially in keeping the
walls of the hole undisturbed. Driving a chisel or other tool with a hammer should not be tried unless no
other method works and then only near the center of the hole. Keep the inside of the hole as free of
pockets and sharp protruberances as possible. Coarse-grained material with plastic fines or fine-grained
soils are easier to dig. Take care to remove all loose particles from the hole and to see that all the
removed particles are included in a container whose weight has been previously determined and
recorded. Weigh the sample and container immediately and record the weight. Keep the lid on the
container as much as possible to prevent excessive moisture loss until it can be weighed. Mark the
container for later identification when the soil moisture content is determined.
Volume-of-Hole Determination
After removing the soil sample from the hole, proceed as follows:
Place the sand-cone apparatus on the metal plate over the hole. Do not jar or shake the container
to cause compaction of the sand.
Open the valve and allow the sand to fill the hole in the ground and space under the cone.
When the sand stops flowing, close the valve, remove the apparatus, and weigh it and the
remaining sand. Record this weight (line 11, Figure 31).
The weight of the sand required to fill the hole equals the weight of the apparatus and sand (line 8
transferred to line 10) minus the final weight (from item above) and minus the weight of sand in the
template and cone (line 9).
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