Geology Reference
In-Depth Information
Note 2 —This method has been proven to provide more consis-
tent, repeatable results than determining the dry mass prior
to testing. This is most probably due to the loss of soil solids
during the deairing phase of testing.
DATA
Data collected in this test should include the following:
[A] Calibration of Pycnometer
Mass of pycnometer, M p (g)
Mass of pycnometer plus water at calibration temperature, M pw,c (g)
Temperature of water at calibration, T c (°C)
[B] Specific Gravity Determination
Mass of pycnometer plus water and soil at test temperature T t ,
M pws,t (g)
Temperature of contents of pycnometer when M pws,t was deter-
mined, T t (°C)
Mass of large evaporating dish or beaker, M d (g)
Mass of large evaporating dish or beaker plus oven-dried soil, M ds (g)
CALCULATIONS [1]
(1) Calculate the specific gravity of soil to the nearest 0.01 using
the equations [1]
# r w , t
M pw , t M p
V p
(6-3)
1
2
where:
M pw,t mass of the pycnometer and water at the test tempera-
ture ( T t ), g,
M p the average calibrated mass of the dry pycnometer, g,
V p the average calibrated volume of the pycnometer (see
Eq 6-2), mL, and
r w, t the density of water at the test temperature ( T t ), g/mL
from Table 6-1.
(2) Calculate the specific gravity of soil solids at the test tempera-
ture, G t as follows:
r s
r w , t
M s
G t
(6-4)
M pw , t
M pws , t M s
1
2
where:
the density of the soil solids, g/cm 3
r s
r w, t
the density of water at the test temperature ( T t ), from
Table 6-1, g/mL or g/cm 3 ,
M s
the mass of the oven dry soil solids (g), and
M pws,t
the mass of pycnometer, water, and soil solids at the
test temperature, ( T t ), g.
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