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The ratios of shear strength for all peats were close to one. This indicates that there
was practically no change in the shear strength of peat with or without N. This implies
that N has little effect on the cementation and pozzolanic reactions. Furthermore, the
dissolution and consumption of calcium, sulphate and potassium ions in N mixtures
were similar to the control mixture.
8.7.3 Effect of pH on treated peat
The impact of pH on cementation and pozzolanic reactions was investigated by varying
the pH of the media. This was carried out by preparing media with different pH values
(3, 5, 7, 10 and 12) by mixing the appropriate amount of hydrogen chloride (HCl) and
sodium hydroxide (NaOH) in distilled water, and measuring the pH with an electronic
pH meter.
It was observed that at low pH (3 and 5), the shear strength ratio of treated peats
(fibrous, hemic and sapric) decreased substantially with curing time, and to a greater
extent in cement than in cement-slag mixtures (Kazemian et al ., 2011s). The decrease
in shear strength ratio occurred for up to 90 days of curing for fibrous peat, but showed
a gradual decrease for hemic and sapric peats. In contrast, at higher pH (10 and 12),
the shear strength ratio showed a nominal increase with curing time for up to 180 days
and the increase was greater for peat treated with cement (Figure 8.10).
The shear strength of the treated peats increased in alkaline media (pH 10 and 12)
because the OH ions liberated during the hydration process were easily utilized when
producing C-S-H gel during the curing process. The negative effect of low pH (3, 5)
on fibrous peat was tangible and was more obvious than on hemic and sapric peats
with both cement and cement-slag mixtures.
8.8 CONTINUING RESEARCH IN PEAT LAND DEVELOPMENT
From the perspective of agriculture, one of the major concerns is that plantation
activities are carried out on relatively unknown terrain. The peat type in the develop-
ment areas will not have been properly characterized and mapped. Proper economic
evaluation cannot therefore be carried out when data or information on the peat
characteristics, hydrology and agriculture potential are lacking or insufficient. It also
results in a lack of direction in the planning and management of the peat development,
which becomes disorganized. This points to a need to have proper planning. There
is also a need to increase knowledge about the ecology of peat land among govern-
ment planners, policy makers and developers when tackling the complex problem of
peat land development. In particular, they need to know about the inter-relationships
between peats, the vegetation it supports, hydrology, nutrient input and cycling, and
decomposition processes.
From the engineering perspective, new construction methods, which are cheaper
and more efficient, and more refined analytical techniques and theories still need to
be found. Continued effort in research and development is vital for the sustainable
development of peat land.
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