According to Wong
(2010), maximum densification to the stabilized soil mix can be achieved by
introducing a suitable amount of well sorted or well graded fine siliceous
material in the form of siliceous sand into it. In addition, Zulkifley et. al
(2014) stated that the increased of the stabilised peat soil mix is provided by
increasing the amount of soil filler particles form (clays, silts or fine
sands) to minimise the void spaces that occurred within the stabilized soil mix
mixture. The use of fillers such as siliceous sand, clay or mineral soil
particles functions to enhance the strength of stabilized peat-cement mix by
supplying more solid particles available for the binder to unite, minimizing
unbridged ‘gaps’ in the pore interstices, thus formed a stabilized, load
sustainable structure (Zulkifley et. al, 2014). The addition of mineral soil as
a filler to increase the number of solid particles might helpful in gain the
strength, because usually peat soil contains very fewer solid particle. The
filler does not react but it will increases the UCS strength by acting as a
stiffener that fill any void formed during the stabilization process. The
addition of Ordinary Portland Cement (OPC) as binder is very important in
gaining the strength of stabilized peat. When the sufficient amount of OPC as
is added, it will neutralized the humic acid within soil thus will increasing
the soil pH; in addition retards the stabilization effect. If the binder is
insufficient and not well dispersed into the soil; has high water-cement ratio,
it will effected the strength of the burnt peat sample. A high water-cement
ratio means more water is present for hydration take place, resulting in a high
porosity and lower strength of the hardened soil-cement paste. Janz and Johansson
(2002) stated that the strength of the hardened cement paste is highly depends
on its porosity and separation between particles. Wider separation between
particles will give the higher porosity, thus lower strength achieved. Sample
specimen from BP-2 and BP-3 in intersect line 1 and BPL3-4 in intersect line 2,
respectively give the higher strength due to enough of water content and cement
to hardened hydration process to take place. In other hand, the UCS strength of
specimen of BP-1 is higher due to presence of clayey material that filled the
void spaces between particles; relatively yield greater strength. The
relatively higher quantity of in situ or mineral soil fillers (or related ash
content) that present either in the topogenic, marginal or shallow peats area
may retarded the strength of the stabilized peat-cement mix due to more solid
particles in the form of naturally deposited mineral soil fillers (clay, silt
or fine sand) are available for the cement binder to form more stabilized,
load-sustainable structure in the cement-peat stabilization process (Zulkifley
et. al, 2014).