Geoscience Reference
In-Depth Information
measured and field performance that relates to compression and water flow. Con-
solidation test results are particularly impacted by gas. The gas content of peat is
difficult to determine and nowidely recognizedmethod is yet available. A gas content of
5-10% of the total volume of the soil is reported for peat and organic soils (
Muskeg
Engineering Handbook
, 1969).
3.8 ORGANIC CONTENT
As mentioned earlier, organic content is an important parameter for peat and organic
soils, which set them apart from the mineral soils (silts and clay). The organic content
is usually determined from the loss of ignition test as a percentage of oven dried mass
(ASTMD 2974). The moist sample is first dried in the oven at a temperature of 105
◦
C
for 24 hours. A crucible is then placed in the muffle furnace at a temperature of 450
◦
C
for 1 hour and weighed to obtain its mass,
M
1
. The dry soil from the oven is then
weighed with the crucible giving
M
2
. The soil sample together with the crucible is
finally heated in the furnace at 450
◦
C for 5 hours, and the mass is then recorded as
M
3
after it has cooled at room temperature. Loss of ignition,
N
, is calculated as
N
=
(
M
2
−
M
3
)
/
(
M
2
−
M
1
)
(3.1)
The organic content (
H
) is calculated according to an equation proposed by Skempton
and Petley (1970) as follows:
H
%
=
100
−
C
(100
−
N
)
(3.2)
where
C
is the correction factor. For a temperature of 450
◦
C, C
1.0 (Arman, 1971).
In Europe, a higher temperature of 550
◦
C is used for combustion of peat, and
C
=
1.04
is then applied as the correction. However, the difference is usually small and hence
not significant for practical considerations (Edil, 2003).
Table 3.2 shows the organic content of various peat deposits found throughout
the world for comparison.
=
Table 3.2
Organic content of various peat deposits.
Peat deposit
Organic content (%)
Antoniny fibrous peat, Poland
65-85
Co. Offaly fibrous peat, Ireland
98-99
Cork amorphous peat, Ireland
80
Cranberry bog peat, Massachusetts
60-77
Italy peat
70-80
Japan peat
20-98
Canada peat
17-80
Hokkaido peat
20-98
West Malaysia peat
65-97
East Malaysia peat
50-98
Central Kalimantan peat
41-99
