Recent advances in the geotechnics of organic soils and peat - Geotechnics of Organic Soils and Peat - page 199

Figure 7.29 CBR (%) values for undisturbed peat and different percentages of OPC and polypropylene
fibres for stabilized peat cured for 90 days.
cement and water are mixed together, the aluminates react with the water to form
an aluminate-rich gel which reacts with sulfate in solution and the cement starts to
hydrate, with the formation of calcium silicate hydrate and calcium hydroxide, and
it gains strength. The polypropylene fibres act as reinforcements to the fibrous peat.
It appears that it prevents the formation of cracks in the sample, and along with the
cement, binds the peat particles together, leading to an increase in CBR values of
the stabilized peat samples. The results agree well with the findings of researchers
(Sivakumar et al. , 2008; Tang et al. 2007), who have also reported an increase in
strength with the addition of cement and polypropylene fibres in clay.
There appear to be some micro-structural changes resulting from the addition of
cement and polypropylene fibres or the interaction between cement and fibre rein-
forcement which is responsible for the increase in UCS, as well as CBR values. Using
the air curing technique instead of normal moist curing also plays an important role
in increasing the strength, as this method keeps lowering the moisture content, and as
this reduces, stabilized samples gain more strength.
7.8.5 Steel fibres
Steel fibres are made of cold drawn steel wire with a low carbon (C) content or stain-
less steel wire. Steel fibres are manufactured in different types; hooked, undulating
or flat, according to the construction project. These fibres are used in construction
for concrete reinforcement. They are mostly used to reinforce of concrete, mortar and
other composite materials. Steel fibre reinforcement products are designed to increase
concrete material performance in a variety of applications. The technical advantages of
steel fibres in concrete include: improve flexural toughness, increase fatigue, enhanced
impact and abrasion resistance, additional load bearing capacity, controlled shrink-
age behaviour and increased durability. Steel fibres can also be used as an addition