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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