Fiber Reinforcement of Clay Soil

The assignment delves into the effectiveness of fiber reinforcement in improving the properties of clay soil. It examines various fiber types, including coir, human hair, and polypropylene, analyzing their impact on key geotechnical parameters such as bearing capacity, consolidation behavior, and shear strength through experimental studies. The summary table highlights relevant research papers focusing on these aspects.

Clay Soil Reinforced with Cocopeat 1
ENGINEERING BEHAVIOUR OF CLAY REINFORCED WITH FIBRES
A Research Paper on Clay Soil By
Student’s Name
Name of the Professor
Institutional Affiliation
City/State
Year/Month/Day

Clay Soil Reinforced with Cocopeat 2
INTRODUCTION
Problem Statement
Clay soil is a cohesive soil with high compressibility and low permeability. This type
of soil shrink under dry condition and swells in a wet condition. Clay soil is not appropriate
for the majority of the projects of construction since it may lead to the foundation to easily
crack leading to the cracking of wall. There is need of using a deep foundation like piling to
prevent cracking of foundation. Piling is normally used in local industries of construction
because of soft clay soil that is weak found in most sections of Brunei Darussalam. There
have been numerous research on ground improvement in Brunei with an aim of widening
treatment techniques of the clay soil to improve its performance (Akhtar, 2013).
Through the process of soil stabilization, the issue of settlement can be prevented
from happening during construction. The swelling and shrinkage of the soil can be minimized
hence improving the soil stability for construction of structures. In this project, the soil
improvement method discussed is the use of fibres to improve the characteristics of clay soil.
The fibres will prevent the cracking of clay soil during construction hence minimizing the use
of gravel and sand due to their high cost. In Brunei, the clay soil is not used in the
construction rather it is excavated during construction and thrown away to a wasteland, the
use of cocopeat will encourage the clay soil to be improved and effective for construction
purposes. The cocopeat inclusions are cheaper and readily available since they are gotten
from the coconut husk (Choudhry, 2014).
LITERATURE REVIEW
The previous research on reinforcement of soil with cocopeat and the consolidation
effects of clay soil are summarized in this section which majorly focuses on the techniques,
procedures as well as the results.

Clay Soil Reinforced with Cocopeat 3
Stress-Strain Behaviour of Coir Fibre Reinforced Clay soil
Unreinforced clay soil specimens prepared at 17.8kN/m3 of dry unit weight portrayed
a very brittle behaviour with 0.9% failure. The specimens were made with the coir fibre
content of 1.6%, 0.8%, and 0.4%. The full consolidation was assumed to occur after the level
of water in the burette which is joined to the valve for drainage becomes constant. The results
of the compaction show that the optimum content of moisture of the reinforced clay with
untreated and treated coir fibre increases with an increase in the content of coir fibre (Kaniraj,
2014).
The optimum moisture content of clay was 12%. The stress-strain behaviour of reinforced
clay with diverse percentages of coir fibre is as shown in figure 1 below. The inclusion of
CCL4 treated coir fibre to the clay resulted in greater frictional angle and cohesion
improvement.
Mechanical Properties of Human Hair reinforced Clay soil
Samples that are saturated were prepared for triaxial compression and conventional
consolidation test. For the samples preparation, there was a consideration of the technique of
slurry. The characteristic of the human hair strength was then determined by the test of tensile
strength. The mechanical and physical properties of the used human hair are as shown in the
figure below. When samples that are saturated are tested in the triaxial apparatus by the
application of the back pressure, the method may take a long duration in case of longer

Clay Soil Reinforced with Cocopeat 4
dimensions of the samples. The human hair reinforced samples and unreinforced samples
with the diverse percentage of human hair content of 30%, 20%, and 10% were mixed with
water that is distilled to form the slurry (Shukla, 2016).
The consolidated undrained triaxial test and one-dimensional consolidation were
conducted on the prepared samples. The results of the one-dimensional consolidation tests are
as portrayed in figure 2 below:
The stress of deviator increases until unreinforced clay attains 15% axial strain, however, for
the samples reinforced, the test proceeds until 20% axial strain is of. From the test of
oedometer, the reinforced and unreinforced samples decrease in pressure as more human hair
are added to the mixture (Pradhan, 2013).
Dynamic Properties of Polypropylene Monofilament Fibres Reinforced Clay
Some of the dynamic properties of a soil sample include tensile strength,
compression, and shear properties. The damping ratio and shear modulus are the two major
variable characteristics of the dynamic response of soil analysis. The specimens were
prepared by mixing clay soil with different polypropylene monofilament fibres percentages.
The compaction test was done on a mixture of polypropylene monofilament fibres with clay
soil after a homogeneous mixture off. The optimum polypropylene monofilament fibres
content was found to be 0.2% for the composite (Sivakumar, 2013). The damping ration

Clay Soil Reinforced with Cocopeat 5
against the shear strain of polypropylene monofilament fibres reinforced clay is as shown in
the graph below:
An increase in the values of shear modulus and damping ration was noted for clay with
cocopeat at low ranges of shear strain.
Performance of Coir Fibre Reinforced Clay soil
The inclusion of discrete coir fibre that is randomly distributed improves the strength
parameters of the clay soil as in case of construction using reinforced concrete. The test of the
model footing was conducted on the coir fibre reinforced clay with an aim of investigating
the behaviour of pressure settlement of coir fibre reinforced clay that is randomly distributed
and the impacts of the content of coir fibre on the bearing capacity (Vasan, 2017). The results
of the maximum dry density for reinforced and unreinforced clay soil using the standard
Proctor compaction test is as shown in the figures 3(a) and (b) below:
(a) (b)
The model footing test was done for reinforced clay and unreinforced clay 1.0%, 0.75%,
0.5%, and 0.25% cocopeat for 25mm, 50mm, and 100mm thickness. The curve of load

Clay Soil Reinforced with Cocopeat 6
settlement for reinforced and unreinforced clay are as shown in the figures 4(a) and (b)
below:
(a) (b)
There is a significant improvement is bearing capacity of clay soil with the inclusion of
cocopeat.
SUMMARY
Table 1
No. Author and
Year
Fibre Preparation of
Sample
Experiment
Performed
Results
1 (Choudhry,
2014)
Coir fibre The coir fibre content
of 1.6%, 0.8%, and
0.4%
Consolidation
test
The results of the compaction show
that the optimum content of moisture
of the reinforced clay with untreated
and treated coir fibre increases with
an increase in the content of coir
fibre. The optimum moisture content
of clay was 12%.
2 (Mali, 2017) Human hair The diverse percentage
of human hair content
of 30%, 20%, and 10%
were mixed with water
Triaxial
compression and
conventional
consolidation
test
The stress of deviator increases until
unreinforced clay attains 15% axial
strain, however, for the samples
reinforced, the test proceeds until
20% axial strain is attained
3 (Shukla, 2016) Polypropylene
monofilament
fibres
The specimens were
prepared by mixing
clay soil with different
Polypropylene
monofilament fibres
percentages
The compaction
test
The optimum polypropylene
monofilament fibres content was
found to be 0.2% for the composite.
An increase in the values of shear
modulus and damping ration was
noted for clay with cocopeat at low
ranges of shear strain.
4 (Kaniraj,
2014)
Coir Fibre The reinforced clay and
unreinforced clay
1.0%, 0.75%, 0.5%,
and 0.25% cocopeat for
25mm, 50mm, and
100mm thickness
The standard
Proctor
compaction test
There is a significant improvement is
bearing capacity of clay soil with the
inclusion of coir fibre.

Clay Soil Reinforced with Cocopeat 7
Bibliography
Choudhry, D., 2014. Mechanical behaviour of polypropylene and human hair fibres and
polypropylene reinforced polymeric composites. Michigan: Int J Mech Ind Eng.
Kaniraj, A., 2014. The geotechnical behaviour of fly ash mixed with randomly oriented fibre
inclusions. New Delhi: Geotext Geomembr.
Mali, S., 2017. Strength Behaviour of Cohesive Soils Reinforced with Fibers. Colorado: International
Journal of Civil Engineering Research.
Pradhan, V., 2013. Effect of random inclusion of polypropylene fibres on strength of cohesive soil.
Bangkok: Geotech Geol Eng.
Puppala, A., 2011. Effect of fibre reinforcement on strength and volume change in expansive soils.
New York: Transportation Research Record.
Shukla, B., 2016. The behaviour of plastic waste fibre-reinforced industrial waste in pavement
applications. Mumbai: Int J Geotech Eng.
Sivakumar, B., 2013. Influence of randomly distributed coir fibres on the shear strength of clay.
London: Geotechnical and Geological Engineering.