Geoscience Reference
In-Depth Information
Figure 7.27
UCS values of various types of plain fibrous peat vs. curing time.
curve up to 28 days is less than the slope beyond 28 days, but for the higher dosage
of cement content (30 and 50% OPC) samples that is reversed. The reason may be
that as the cement content of the samples is increased to higher amounts (30%, and
specially 50% OPC) more strength is gained through first 28 days, and the stabilized
samples may behave similar to the behaviour of cement mortar mixes (cement, sand
and water) which they gain most of their strength within first 28 days (Neville, 1999).
Also, the results obtained fromUCS values for plain fibrous peat, with and without
PPF, cured for 90 days and tested as unsoaked and soaked samples, shown in Figure
7.27 indicate that plain fibrous peat treated with and without PPF increases its UCS
after 90 days of air curing by factors of 8 (from 28.5 to 240) and 6 (from 28.5 to
170 kPa), respectively. Soaking the identical air cured fibrous samples, on the other
hand, causes the UCS value of fibrous peat with fibres to drop by factor of 6 (from 240
to 39 kPa), and the sample without fibres loses all of its strength (from 170 to 0 kPa)
when soaked.
Figure 7.28 shows the reduction in moisture content for various types of treated
peat samples through an air curing period from just after mixing up to 90 days. Com-
paring the results of treated peat samples having various amount of OPC in this figure
indicates that stabilized samples containing 5% ordinary Portland cement continue to
lose moisture content at a faster rate than other types of stabilized samples, and with
a sharper slope during the curing periods. The final moisture content of samples with
5% OPC at the end of the 90 days curing period is close to that of stabilized samples
treated with 30% OPC.
At the same time, if the 90 days cured UCS (unsoaked) values of samples with 5%
OPC shown in Figure 7.22 are compared with other results shown in Figures 7.23-7.25
belonging to stabilized peat samples containing 15, 20 and 30%OPC respectively, it is
possible to observe that the unsoaked UCS values of samples having only 5% OPC is
relatively higher than those of samples having greater OPC content. This phenomenon
