Geoscience Reference
In-Depth Information
Figure 7.22
Unconfined compressive strength (UCS) values for fibrous peat and 5% OPC with and
without polypropylene fibres (PPF) vs. curing time.
The minimum dosage rate of PPF recommended for concrete mixes starts at
0.6 kgm
−
3
(Sika Fibres 2005). Also, Tang
et al.
(2007) tried 0.05, 0.15 and 0.25% (by
soil weight) of polypropylene fibres (PPF) through UCS tests to find the optimum PPF
amount to strengthen cement-treated clay soil.
Kalantari
et al.
(2011) examined polypropylene fibre (PPF) as an additive used
in OPC-treated fibrous peat samples, and its effect was evaluated through UCS. Air
curing was used to cure the OPC treated fibrous peat samples with PPF.
Different types of UCS test samples made of fibrous peat with a moisture content
of 198% and various amounts of OPC (5, 15, 20, 30 and 50%) and 0.15% PPF
were prepared, and then cured for up to 90 days. UCS tests were then conducted on
stabilized samples immediately after mixing (0 day), 7, 28 and 90 days. Soaked UCS
tests were also conducted on 90 days air cured samples by submerging them in water
for seven days prior to being tested. The results are shown in Figures 7.22-7.26.
UCS tests were also conducted on plain (untreated) fibrous peat samples imme-
diately after mixing (0 day) and after 90 days, in unsoaked (cured in air), and
soaked (cured 90 days in air, and then soaked for seven days). The result is shown
in Figure 7.27.
The results in Figures 7.22-7.27 show that:
(a)
As the OPC amount is increased in stabilized samples with or without PPF, the
immediate (0 day) and soaked UCS values increase as well.
(b)
Addition of 0.15% polypropylene to the OPC-treated fibrous peat samples
increases the UCS values of the air cured stabilized samples.
(c)
UCS values increase from 28 days to 90 days of curing periods for samples
containing 5% OPC by over 142% (from 128 to 310), and 196% (from 135 to
400), and for 15% by over 135% and 196%, and also for samples containing
