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Figure 7.32 Photographs of (a) polypropylene fibres; (b) steel fibres ( after Kalantari et al. , 2011).
has been overcome with some success by incorporating randomly oriented fibres (rein-
forcement) within the soil which help by limiting the potential planes of weakness that
develop with parallel oriented reinforcement. An increase in the compressive strength
of the samples, due to the addition of fibres, has been reported by many researchers
(Consoli et al ., 2009; Maher and Ho, 1993; Park and Tan, 2005; Tang et al ., 2007).
Kalantari et al. (2011) have attempted stabilizing peat using ordinary Portland
cement (OPC) as a binding agent and polypropylene (Figure 7.32(a)) and steel fibres
(Figure 7.32(b)) as chemically inert additives. CBR and UCS tests were carried out to
evaluate the increase in strength of the stabilized samples.
The results of UCS tests on peat samples (showing an increase in UCS) with 5 and
15% OPC, different percentages of polypropylene and steel fibres, compacted at their
optimum moisture content (OMC) and then air cured for 90 days, are presented in
Figure 7.33.
Further, the results of the CBR test carried out on stabilized peat samples com-
pacted at their OMC with 5% OPC, polypropylene fibres and steel fibres, and air
cured for 1, 28 and 90 days are presented in Figure 7.34(a). Similarly, the results with
15% and 30% OPC and polypropylene fibres and steel fibres are presented in Figures
7.34(b) and (c) respectively.
Munro (2004) has also reported an improvement in the CBR when OPC is added
to peat. An improvement in CBR of fly ash, upon addition of cement, has also been
reported by Leelavathamma et al. (2005).
7.9 PEAT STABILIZATION BY REINFORCED COLUMNS
Huat (2004), Kalantari and Huat (2009b), Moayedi et al . (2009), Kazemian and Huat
(2009b) and Edil (2003) summarized a number of construction options that can be
applied to peat and organic soils, namely excavation-displacement or replacement;
ground improvement and reinforcement to enhance soil strength and stiffness, such as
by stage construction and preloading, stone columns, piles, thermal pre-compression
and preload piers; or by reducing driving forces by lightweight fill; and chemical
admixture such as cement and lime.
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