Geoscience Reference
In-Depth Information
Figure 7.28
Moisture content reductions versus curing periods for various types of treated fibrous
peat samples.
may be explained by the fact that as the treated fibrous samples lose their moisture
content through the air curing period, they gain strength because of their wooden
fibre content. According to Figure 7.28, this condition is more relevant to samples
containing less OPC (5%). As these woody fibres, whichmake upmost of the structural
identity of fibrous peat, lose their moisture and become drier, the samples become more
solid and thus gain more strength. As soon as the stabilized samples containing less
OPC (samples with 5% (Figure 7.22) or 0% (Figure 7.27)) are soaked, their gain in
strength decreases significantly, and their actual strengths are revealed.
CBR tests were conducted on various types of OPC treated fibrous peat for their
unsoaked as well as soaked CBR values. The CBR samples first were air cured for three
months, and then tested under unsoaked and soaked conditions. Figure 7.29 shows
the results, indicating that:
(a)
For stabilized fibrous peat with 15% OPC, cured for 90 days, the unsoaked and
soaked CBR increase by factors of over 23 (from 0.8 to 19%) and 9 (from 0.8 to
7.2%), respectively
(b)
For stabilized fibrous peat with 15%OPC, 0.15% polypropylene fibres, cured for
90 days, the unsoaked and soaked CBR increase by factors of over 28 (from 0.8
to 23) and over 18 (from 0.8 to 15).
Three months of air curing, as well as 15% OPC and 0.15% polypropylene fibres
used to stabilize fibrous peat, will increase the general rating of
in situ
peat from very
poor (CBR from 0 to 3%) to fair and good (CBR from 7 to above 20%) (Bowles,
1978).
Peat samples stabilized with OPC and polypropylene fibres show an increase in
CBR values by as much as 39% (with 50% OPC). The OPC acts as a binding agent
and is responsible for the increase in the mechanical strength of the samples. When
