Geology Reference
In-Depth Information
Figure 9-1
Definition of Shrinkage
Limit
Plasticity Index
Water Content (%)
where:
R
shrinkage ratio
V
soil volume change, cm 3
Δ
V o
volume of oven-dried soil, cm 3
w
change in water content, g
Δ
M o
mass of oven-dried soil, g
Because
w
(
V )(
ρ w ), where
ρ w is the unit mass of water in g/cm 3 ,
Δ
Δ
Eq. (9-1) may be rewritten as
¢ V
V o
>
R
1
¢ V
21
ρ w
2>
M o
or
M o
R
V o
1
21
ρ w
2
Because the unit mass of water,
ρ w , is 1 g/cm 3 , the shrinkage ratio may
be expressed simply as [1]
M o
V o
R
(9-2)
Evaporating dish [about 140 mm (5 1 2 in.) in diameter; see Figures
9-2 and 9-3]
APPARATUS
AND SUPPLIES
Spatula
Shrinkage dish (see Figures 9-2 and 9-3)
Straightedge (steel)
Glass cup [about 57 mm (2 1 2 in.) in diameter and about 31 mm
(1 1 4 in.) in height; see Figures 9-2 and 9-3]
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