Environmental Engineering Reference
In-Depth Information
Table 2.1 Specific Gravity of Several Minerals
to be taken into consideration when there is a phase change
as temperature is changed. Rocks and minerals exist only in
the solid phase for most geotechnical engineering problems.
Specific heat capacity
C
s
is defined as the quantity of heat
required to raise the temperature of a unit mass of material
by one degree Kelvin. The SI units for specific heat capacity
are kilojoules per kilogram per degree Kelvin (kJ/kg K). An
average value for the specific heat capacity for rocks and
minerals is 0.85 kJ/kg K. Specific heat capacity values for
a series of rocks and minerals are presented in Table 2.2
(Tarnawski and Wagner, 1991).
Thermal conductivity
λ
s
is defined as the ability of the
material to transmit heat through conduction. The SI units
for thermal conductivity are Watts per meter per degree
Kelvin (W/m/ K). Typical values for the thermal conductiv-
ity of various rocks and minerals are presented in Table 2.2.
The thermal conductivity can be seen to vary from about 1
to 7 for most materials with hematite showing a value of
about 11.3 W/m K.
Mineral
Specific Gravity,
G
s
Quartz
2.65
K feldspars
2.54-2.57
Na-Ca feldspars
2.62-2.76
Calcite
2.72
Dolomite
2.85
Muscovite
2.7-3.1
Biotite
2.8-3.2
Chlorite
2.6-2.9
Pyrophyllite
2.84
Serpentine
2.2-2.7
2.61
a
;2.64
Kaolinite
±
0.02
Halloysite (2H
2
O)
2.55
2.84
a
; 2.60-2.86
Illite
2.74
a
; 2.75-2.78
Montmorillonite
Attapulgite
2.30
2.3.2 Water Phase
The water phase plays an important role in the behavior
of soils. There are several physical properties that are of
particular interest when dealing with soils. Water may exist
Source:
From Lambe and Whitman, 1979.
a
Calculated from crystal structure.
the specific gravity of the solid phase. Specific volume
v
0
is generally defined as the inverse of density; therefore,
specific volume is the ratio of volume to mass.
The density of the soil particles,
ρ
s
, is defined as
Table 2.2 Specific Gravity and Thermal Properties
of Solid Minerals
M
s
V
s
Minerals
Specific Heat
Thermal
ρ
s
=
(2.9)
and
Capacity,
C
s
Conductivity,
Specific
λ
s
(W/m K)
Gravity,
G
s
Rocks
(kJ/kg K)
where:
Quartz
0.698
7.69
2.65
M
s
=
mass of solids and
Calcite
0.793
3.57
2.71
V
s
=
volume of solids.
Dolomite
0.930
5.50
2.86
Orthoclase
0.610
2.31
2.58
The specific gravity of the soil particles is defined as the
ratio of the density of the soil particles to the density of water
at a temperature of 4
◦
C under standard pressure conditions
(i.e., 101.3 kPa). In the International System of Units (SI),
the specific gravity is referred to as the relative density of
the soil particles:
Muscovite
—
2.32
2.85
Biotite
—
1.17
2.98
Chlorite
—
5.14
2.64
Talc
0.870
6.10
2.82
Hematite
0.610
11.28
5.14
Granite
0.880-1.382
1.65-2.83
2.60-2.65
ρ
s
ρ
w
Gneiss
0.766-0.871
2.58-2.94
2.70-2.73
G
s
=
(2.10)
Marble
0.750
2.79-2.89
2.60-2.69
Limestone
0.825-0.950
1.70-2.68
2.41-2.67
The density of water at 4
◦
C and 101.3 kPa is 1000 kg/m
3
.
Some typical values of specific gravity
G
s
for soil solids are
presented in Table 2.1.
Sandstone
0.762-1.072
2.18-5.10
2.35-2.97
Slate
0.779
1.89-2.59
2.70-2.76
Organics
1.923
0.25
1.30
2.3.1.2 Thermal Properties of Solids
There are two thermal properties that are of primary interest in
geotechnical engineering: specific heat capacity and thermal
conductivity. There are also phase change properties that need
Source
: From Tarnawski and Wagner, 1991.
Note:
The thermal properties of solids, water, and air can be
combined to provide typical thermal properties for various
soil types and mixtures.
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