STRENGTH CHARACTERISTICS OF RANDOMLY DISTRIBUTED … · When added to the fibre reinforcements in the soil, it acts as a disinfectant, improving the durability of the material, while

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International Journal of Civil Engineering and Technology (IJCIET)Volume 8, Issue 5, May 2017, pp.

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ISSN Print: 0976-6308 and ISSN Online: 0976

© IAEME Publication

STRENGTH CHARACTERISTICS OF

RANDOMLY DISTRIBUTED COCONUT COIR

REINFORCED LITHOMARGIC CLAY

Professor, Department of Civil Engineering, MIT, Manipal University, Manipal

Asst. Professor, Department of Civil Engineering,

Aayush Sharma

Final year B.Tech students, Department of Civil Engineering, MIT, Manipal University,

ABSTRACT

The Lithomargic Clay is a

Konkan belt of South India. The problematic soil loses its strength under wet

conditions and tends to flow with the water leading to the formation of cavities and

unsettlements. Thus, proving the soil to be highly unstable for heavy

work and since the construction on this soil is unavoidable, there is an immediate

need for detailed investigations to improve

increase the strength parameters of the locally available Lithomargic clay by

reinforcing it with randomly distributed untreated coconut coir fibres and then by

adding a coating of Cashew Nut Shell Liquid Oil, a commonly used industrial

disinfectant, on the fibres to improve its durability. The study focused on the proposal

of only locally available material, to provide an economical and efficient solution to

the problem. It was observed that with the inclusion of coir fibres, the strength

parameters of the soil improved, with the cohesion of the soil increasing by almost

five times when reinforced with untreated randomly distributed coir fibres and by six

times when a coat of CSNL Oil was applied to the fibres.

Key words: Stabilisation,

oil (CNSL).

Cite this Article: Purushotham G. Sarvade, Deepak Nayak, Aayush Sharma,

RaginiGogoi and SagarMadhukar Strength Characteristics of Randomly Distributed

Coconut Coir Reinforced L

Engineering and Technology

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International Journal of Civil Engineering and Technology (IJCIET) 2017, pp. 1122–1134, Article ID: IJCIET_08_05_119


6308 and ISSN Online: 0976-6316

Scopus Indexed




Purushotham G. Sarvade

Professor, Department of Civil Engineering, MIT, Manipal University, Manipal

Deepak Nayak

Asst. Professor, Department of Civil Engineering, MIT, Manipal University, Manipal

Aayush Sharma, RaginiGogoi and SagarMadhukar


Manipal.

Lithomargic Clay is an abundantly available soil type in the high rainfall



unsettlements. Thus, proving the soil to be highly unstable for heavy


need for detailed investigations to improve its stabilisation. The paper aims to


einforcing it with randomly distributed untreated coconut coir fibres and then by



ocally available material, to provide an economical and efficient solution to



hen reinforced with untreated randomly distributed coir fibres and by six

times when a coat of CSNL Oil was applied to the fibres.

, Randomly distributed coir fibres, Cashew nut shell liquid

Purushotham G. Sarvade, Deepak Nayak, Aayush Sharma,


Coconut Coir Reinforced Lithomargic Clay. International Journal of Civil

Engineering and Technology, 8(5), 2017, pp. 1122–1134.


[email protected]

asp?JType=IJCIET&VType=8&IType=5




Professor, Department of Civil Engineering, MIT, Manipal University, Manipal.

MIT, Manipal University, Manipal.

SagarMadhukar


e in the high rainfall



unsettlements. Thus, proving the soil to be highly unstable for heavy construction


stabilisation. The paper aims to


einforcing it with randomly distributed untreated coconut coir fibres and then by



ocally available material, to provide an economical and efficient solution to



hen reinforced with untreated randomly distributed coir fibres and by six

Randomly distributed coir fibres, Cashew nut shell liquid

Purushotham G. Sarvade, Deepak Nayak, Aayush Sharma,


International Journal of Civil


Strength Characteristics of Randomly Distributed Coconut Coir Reinforced Lithomargic Clay

http://www.iaeme.com/IJCIET/index.asp 1123 [email protected]

1. INTRODUCTION

Manipal is a small educational suburb of the city of Udupi in Coastal Karnataka, South India.

A rise in its population and fast growing industries in the adjoining areas of Mangalore and

Udupi has exposed this placid town to rapid urbanization, compelling Civil Engineers to

make the dominantly available soft, Lithomargic Clay (locally known as Shedi Soil), fit for

heavy construction.

Lithomargic Clay is a soft soil, generally classified as silty sand or sandy silt with a high

content of silt. [1] It possess low shear strengths and bearing capacities with high

compressibility. [2] The soil is susceptible to water, losing a significant portion of its strength

under wet conditions. Thus as long as it is confined and dry, there is negligible problem but

when it comes in contact with water, it loses its strength significantly. [3] These factors make

the land highly prone to erosions, slope failures, foundation failures, embankment failures

and uneven settlement over time. The occurrence of such failures has made the development

and application of various ground improvement techniques necessary.

One such widely accepted technique is soil stabilisation. Soil stabilization involves

altering the soil to improve its geotechnical problems, aiming to increase its strength and

softening resistance by bonding the soil particles together or by water proofing the

particles.[4] An economical and efficient method of soil stabilization is using fibres as soil

reinforcements. They are incorporated into the soil either in the form of geogrids or randomly

distributed throughout. Synthetic, for example geomaterials in the form of geogrids,

geotextiles, geofibres, as well as natural fibres, for example coconut coir, jute, etc serve the

purpose. Naturalfibres are desired more from an economical and environmental point of view,

and their use as a soil reinforcement is a big leap towards sustainable building materials.

Coconut coir is one such abundantly available natural, local product. Amongst other

natural fibres, it has the benefit of retaining more than 80% of its tensile strength even after 6

months of its induction into the soil, [5] thus better strength characteristics and resistance to

biodegradation over a longer period. [6]

Apart from these, advances have been made in the field of natural fibre-polymer

composites. These hybrids combine the durability and binding strength of polymers with the

mechanical properties of natural fibres. One such hybrid of coconut coir fibre coated with

Cashew Nut Shell Liquid oil has been proposed in this paper. The oil has been used for

generations as a traditional disinfectant, which can be used to compensate the short life spans

of the natural coir fibres.

1.1. Lithomargic Clay

Lateritic soil is commonly found throughout the entire stretch of the Konkan belt in South

India. This soil is hard and strong, though very porous. 1-3m below the top outcrop of the

soil, Lithomargic clay, an important residual soil of the former, is present. [3] It is whitish,

pinkish, or yellowish in colour with the white particles being the weakest. The soil comprises

of hydrated alumina and kaolinite powder and is a product of tropical and subtropical

weathering. This layer constitutes of particles with size distribution between silt and clay, but

behaves like neither. [7] Under moist conditions, it loses a significant portion of its strength

and tends to flow along with water during heavy rains. This causes the formation of cavities

and uneven settlements on the application of loads, resulting in slope failure. Thus, engineers

have to be very cautious when working with such soil.

Purushotham G. Sarvade, Deepak Nayak, Aayush Sharma, RaginiGogoi and SagarMadhukar


1.2. Coconut Coir Fibre

Coir fibre is a hard structural fibre extracted mechanically from the husk of a coconut.

Indigenous to tropical climate, India and other South East Asian countries dominate their

production in the world market. It is abundantly available in the coastal areas of the country,

making it a local, and thus economical, option over other natural fibres. Apart from

contributing to sustainable development, using them as soil reinforcements enhances the

geotechnical nature of the soil. Studies have shown that when they are randomly distributed

in the soil, they maintain a strength isotropy and reduce the possibility of the formation of a

weak zone. It imparts tensile strength to the soil composite which is a key requirement since

the soil under examination possesses high compressive strength but low tensile strength. They

also convert the brittle behaviour of the soil to ductile behaviour due to its ability to undertake

permanent stretch. [6] Compared to other natural fibre, coir fibre has higher lignin content,

making them stronger and more resilient.[8]

1.3. Cashew Nut Shell Liquid Oil

Cashew Nut Shell Liquid Oil (CNSL) is a versatile by-product of the Cashew Industry. It is a

viscous liquid with a honey comb structure, found inside the shell of the nut. It is vastly

produced in the country, with the state of Karnataka producing one third of the total.

It is a renewable and eco-friendly material with a high chemical resistant property. Due to

its anti-microbial and acid resistant properties, it has innumerable applications in the polymer

based industries, along with the energy sector, automobiles, etc. When added to the fibre

reinforcements in the soil, it acts as a disinfectant, improving the durability of the material,

while increasing its strength by providing better bond between the fibre and the soil.

2. LITERATURE REVIEW

The concept of reinforcing soil to increase the shear resistance of the composite was first

introduced by Vidal and since then this field has been subjected to extensive research. Studies

have been conducted to analyse the effect of the aspect ratio and fibre percent of the different

soil properties.

Pradhan, Kumarkar and Naik [9] investigated the effects of aspect ratio and fibre

percentages on the strength parameters of a cohesive soil modified with a synthetic

polypropylene fibre. To avoid the formation of predefined failure planes, the method of

random distribution of fibres was adopted and it was observed that with the initial increase in

the fibre length there was an increase in the shear strength parameters but subsequent

increases resulted in a decreasing trend. This was speculated to be due to the fall in the soil

available for bond formation with the coir fibres. Dasak and Sumesh’s [10] study on the shear

strength of kaolin soil with randomly distributed coir fibres resulted in the same conclusion,

with the optimum fibre length recommended as the lower aspect ratio in the study. Maliakal

and Thiyyakkandi [6] in their study conducted the same tests on the soil to develop a

mathematical model to predict the major principle stress at the failure for the clay-fibre

composite. They conducted experimental studies on two types of clay whose results were

employed to develop the regression model which was then verified with the results of the

third type of clay. Various studied have also been conducted to understand the effects of the

different types of natural fibres available for soil reinforcement. Biswas and Ahsan [11]

studied the various mechanical and physical properties of natural fibres of jute, bamboo and

coconut at different span lengths. On similar lines, Maity, Chattopadhyay and Mukherjee [12]

conducted a comparison of jute, coconut and a locally available Sabai grass on their

effectiveness as reinforcement to natural sand for sub base construction, and the results

showed the better performance of jute and coir over the grass. Ali [5] conducted further



studies on the different chemical and physical properties of coconut coir and their effects as

soil reinforcement. The paper justified the versatility of coir. The results clearly demonstrated

that it was the most tensile of all natural fibres, and its ability to retain it in under different

chemical testing. Apart from the conventional natural fibres used, advances have also been

made in the testing of new locally available materials in soil reinforcement. Adili, Azzam,

Spagnoli and Schrader [13] investigated the effect of papyrus on the strength and stiffness

response of the modified soil, by conducting a series of direct shear tests and consolidation

tests. The paper concluded with the considerable increases observed in the cohesion and

stiffness of the modified soil. Apart from the research work conducted so far, there is still

scope for further development in the field of fibres as soil reinforcement.

3. MATERIALS AND METHODS

3.1. Materials

3.1.1. Lithomargic Clay Soil Sample

The Lithomargic Clay used in the study was obtained from a site near Katpadi-Palli Road,

Udupi District (Karnataka State, India). The soil was encountered at a depth of approx. 1.5-

3m from the surface. Disturbed soil samples, in plastic bags and undisturbed soil samples, in

core cutters were brought to the lab for testing. The properties of the soil obtained after

conducting the basic geotechnical tests have been tabulated in Table 3.1.

Table 3.1 Basic geotechnical properties of the soil sample

Table 3.2 Coir Fibre Properties

Physical property Value

Classification MI

Specific Gravity 2.67

Liquid Limit 49.60%

Plastic Limit 30.39%

Shrinkage Limit 28.36%

Plasticity Index 18.67

Flow Index 15.49

Toughness Index 1.21

Maximum Dry Density 1.548N/mm3

Optimum Moisture Content 25%


Diameter 0.2mm

Aspect ratio Selected

for the study

75 (l=15mm),

100(l=20mm),125(

l=25mm),150(l=30mm),

175(l=35mm)

Fibre Content Selected

for the Study 0.25%, 0.5%, 0.75%, 1%



a c

b

3.1.2. Coconut Coir Fibres

The coconut coir fibres were attained from Kalpakrutti Karnataka State Coir Development

Corporation near Sastan, Udupi District (Karnataka State, India). The properties of the

coconut coir fibres have been tabulated in Table 3.2.

Figure 1 a. Different layers of soil at site b. Soil Site

c. Undisturbed Soil Sample collected using Core Cutter

a b c

Figure 2 (a) Coconut coir fibre (b). Cashew Nut Shell Liquid Oil (c). Specimen reinforced with

randomly distributed coir fibre for UCS test

3.1.3 Cashew Nut Shell Liquid Oil

The oil used in the study was attained from Anup Industries located in the town of Hiriyedka,

Udupi District (Karnataka State, India). The specifications of the same according to the I.S.

are given in Table 3.3.



3.2. Testing Procedure

To study the variation in the strength characteristics of the soil when reinforced with

randomly distributed untreated coconut coir fibres and coconut coir fibres coated with

Cashew Nut Shell Liquid oil, a series of Unconfined compressive strength tests were

conducted. For this, the aspect ratios, AR (AR=length/diameter) selected were

75,100,125,150 and 175. It was limited to 175 since the corresponding length of fibre was

35mm, which is very close to the diameter of the mould used to conduct the Unconfined

Compressive Strength tests, ensuring placement of the fibres without bending. Fibre

percentage selected were 0.25%, 0.5%, 0.75% and 1% by dry weight of soil.

Table 3.3 IS Specifications of Cashew Nut Shell Liquid Oil

Standard proctor tests were performed on the basis of the guidelines provided in IS:

2720(part VII) 1965, for each combination of AR with the fibre percentages. The UCS and

the DS tests for each combination was conducted with the maximum dry densities and the

optimum moisture content obtained from their corresponding proctor test.

To prepare the specimen for testing, the dry soil was sieved through a 4.25µm IS sieve,

oven dried overnight and then air dried for 30 minutes. The samples were prepared with

utmost care, to ensure uniform mixing of coir and soil to avoid accumulation of the fibres.

For the UCS and the DS tests, dry soil of specified weight was mixed with the required water

content and kept in the dessicator for 15 minutes to attain moisture equilibrium. Coir fibres of

the agreed quantity were then added to the wet soil and again kept in the dessicator for an

hour. This entire process ensured a uniform distribution of the coir fibre with the soil since

fibres tend to segregate when mixed with dry soil.

For the Unconfined compressive tests, the above mix was compacted into a mould of

38mm diameter and 76mm height and tested, according to IS:2720 (Part-X) 1991, till

concurrent results were obtained.

For Direct shear tests, the prepared modified soil was first added to a steel box of the

same dimensions as that of the shear box used (60mm*60mm*35mm),with openings at the

top and the bottom, before being slid into the shear box and tested according to the guidelines

in IS:2720 (Part-XIII) 1972. This practice was adopted due to the sensitivity of the shear box

and to ensure a uniform compaction.

The combination with randomly distributed untreated coir fibres which gave the optimum

results were further tested with a Cashew Nut Shell Liquid (CNSL) Oil coat. The coir was

soaked in the oil, then left to dry under the sun for 48 hours. Once the oil had coagulated, the

same procedure was followed as in the case of untreated coir as reinforcement to conduct the


Specific Gravity at

30ᵒC 0.95-0.97

Viscosity at 30ᵒC 550

moisture % by weight 1

Loss in weight on

heating 2

Ash % by weight 1

Iodine Value 1

Colour shall not be deeper that dark

brown when viewed by transmitted light



unconfined compressive strength test and direct shear tests. The maximum dry densities and

the optimum moisture contents adopted for the tests were the same as their corresponding

untreated coir reinforcement tests.

3.2.1. Tests on Coconut Coir Fibre

The coconut coir sample used as reinforcement in the study was analysed under a Scanned

Electron Microscope (SEM) to attain the average diameter, and understand its structure and

elemental composition. They were then compared to that of the coconut coir fibre treated

with a coating of Cashew Nut Shell Liquid oil.

4. RESULTS AND DISCUSSSIONS

4.1. Elemental Composition of the Coconut Coir Fibre

The changes in the structural and mineralogical aspects of the untreated coconut coir fibre

when coated with Cashew Nut Shell Liquid oil was studied by analysing them under a SEM.

Images of the sample before and after the application of the oil, magnified to the order of

100X are presented in Fig.3. It can be observed that due to the oil coating, the smooth surface

of the fibre has been converted to a rough, irregular one. This irregularity in the structure will

lead to stronger bond formation, thus increase in the shear strength parameters can be

anticipated.

The elemental compositions of the two coir samples have been tabulated in Table 4.1. It

can be observed that due to the application of the Cashew Nut Shell Liquid oil the Carbon

content and the oxygen content in the fibre has increased and decreased respectively. Traces

of potassium, alumium and silica present in the untreated sample have also vanished in the

treated sample.

a b

Figure 3 Scanned Electron Microscope image of (a) Untreated coir fibre (b) Coir fibre treated with

CSNL Oil



Quantitative results

Weig

ht%

0

20

40

60

80

C O Al Si K

Quantitative results

We

igh

t%

0

20

40

60

80

C O K

a b

Figure. 4 (a) Elemental Composition of Untreated coir fibre Figure 4 (b) Coir fibre treated

with CSNL oil

Table 4.1 Elemental Composition of Untreated coir fibre; Coir fibre treated with CSNL oil

4.2. Randomly Distributed Coconut Coir Fibres as Reinforcement

The strength parameters for the soil reinforced with randomly distributed coir fibres have

been analysed on the basis of the series of Standard proctor tests and Unconfined compressive

strength conducted. Standard proctor tests were conducted to attain the maximum dry density

and the optimum water content for each combination of the proposed aspect ratio and the coir

percentage. Fig 5, Fig6 and Fig.7 presents the density vs. Moisture content for each. It can be

observed that in most of the cases, with the increase in the fibre content, the value of

maximum dry density decreases. This can be attributed to the replacement of the denser soil

with a lighter coir fibre. The field density of the soil was calculated to be 1.308g/cm3, where

as that of coconut coir fibre is on an average 1gm/cm3.

The densities obtained from the above tests were used to conduct compressive strength

tests. The tests were carried out with the MDD and the OMC since they best represent the

field conditions for which the soil requires reinforcement. Fig.8 to Fig.11 present the stress

vs. strain graphs for different aspect ratios. In each graph, the aspect ratio was kept constant

and the effect of the varying fibre percentages was analysed. A general trend of rise in the

compressive strength and then a subsequent fall after reaching the peak can be observed with

Untreated coir fibre

Elements Weight %

C 61.75

O 36.55

Al 0.66

Si 0.62

K 0.42

Coir fibre treated with SNL

Element Weight %

C 76.75

O 22.73

K 0.53



0.0120

0.0130

0.0140

0.0150

0.0160

0.0170

10.00 30.00 50.00

Dry

De

nsi

ty (

N/m

m3)

Water Content (%)

0.75

%

0.50

%

0

0.0120

0.0130

0.0140

0.0150

0.0160

0.0170

10 30 50

Dry

De

nsi

ty (

N/m

m3)

Water Content (%)

Unreinforc

ed

0.25%

0.50%

0.75%

0.0120

0.0130

0.0140

0.0150

0.0160

0.0170

0 50Dry

De

na

ity

(N

/mm

3)

Water Content (%)

Unreinforc

ed0.25%

0.50%

0.75%

1% 0.012

0.013

0.014

0.015

0.016

0.017

5 25 45

Dry

De

nsi

ty (

N/m

m3)

Water Content (%)

Unreinfor

ced

0.25%

0.50%

0.75%

the increase in the percentage of coir fibre added, for all aspect ratios. 0.5% and 0.75% of

fibre to the dry weight of soil showed the maximum increse in strenght, with the value

decreasing again for 1%. Thus, tests were conducted till the addition of only 1% of fibre to

the dry weight of soil. Although the addition of coir fibres are expected to increase the

strength of the soil, the fall can be justified with the decrease in the availability of soil for the

fibre to form an effective bond with. Also, it was observed that this increase in the proportion

of fibre content casuses balling of fibres which leads to the foramation of weak zones. Thus

the maximum percentage added was limited to 1% by dry weight of the soil. Fig11.a presents

the stress vs. Strain curves for the optimum conditions of each aspect ratio. It is clear form the

graph that the highest increase was witnessed for the aspect ratio 75 with a 0.5% fibre

content. The compressive strength increased by 92% from the unreinforced soil.

Thus the unconfined compressive tests concluded that soil reinforced with randomly

distributed coir fibre of aspect ratio 75 with a 0.5% fibre content provided the optimum

results.

a b

Figure 5. Dry Density vs. Water content curves for Soil reinforced with untreated coir fibre randomly

distributed at (a) AR =75 (b) AR=100

A b

Figure 6 Dry Density vs. water content curves for Soil reinforced with untreated coir fibrerandomly

distributed at (a) AR =125 (b) AR=150



0

0.05

0.1

0.15

0.2

0.25

0.3

0.000 5.000

Str

ess

(N

/mm

2)

Strain%

Unreiforced

SoilAR 100 (0.25%)

AR 100(0.5%)

AR 100 (0.75%)

AR 100 (1%)

0

0.1

0.2

0.3

0.4

0.0 2.0 4.0 6.0

Str

ess

(N

/mm

2)

Sttrain %

Unreinforced

AR75 (0.25%)

AR 75 (0.5%)

AR75(0.75%)

AR 75(1%)

0.012

0.013

0.014

0.015

0.016

0.017

5 25 45

Dry

De

nsi

ty (

N/m

m3)

Water Content %

Unrein

forced0.25

0.5

0.75

1%

Figure 7 Dry Density vs. water content curves for Soil reinforced with untreated coir fibre randomly

distributed at AR=175

Figure 8 Stress vs. Strain curves for Soil reinforced with untreated coir fibre randomly distributed at

(a) AR =75

a b


(a) AR =100 and (b) AR=125

0

0.05

0.1

0.15

0.2

0.25

0.3

0.0 5.0

Str

ess

(N

/mm

2)

Strain %

Unreiforced

Soil

AR

125(0.25%)

AR 125

(0.5%)

AR 125

(0.75%)



0

0.1

0.2

0.3

0.000 5.000 10.000

Str

ess

(N

/mm

2)

Strain %

Unreiforced

Soil

AR 150

(0.25%)

AR 150

(0.5%)

AR 150

(0.75%)

0

0.1

0.2

0.3

0.000 2.000 4.000

Str

ess

(N

/mm

2)

Strain%

Unreiforced

Soil

AR

175(0.25%)

AR 175

(0.5%)

AR

175(0.75%)

(a) (b)


(a) AR =150 and (b) AR=175

Figure 11. (a)Stress vs. Strain curves for Soil reinforced with untreated coir fibrerandomly distributed

at the optimumfibre percentage for each Aspect Ratio.(UCS Test)

Figure 12 UCS Test specimen for soil reinforced with randomly distributed untreated coir fibre

0

0.050.1

0.150.2

0.250.3

0.350.4

0.000 5.000

Str

ess

(N/m

m2)

Strain %

Unreiforced Soil

AR 75 (0.5%)

AR 100 (0.5%)

AR 150 (0.75%)

AR 125 (0.75%)

AR 175 (0.5%)



0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 2 4 6 8

Str

ess

(N/m

m2

)

Strain %

Unreinfiorced soil

Soil reinforced

with randomly

distributed

untreated coir

fibre

Soil reinforced

with randomly

distributed coir

fibre coated with

CSNL Oil

4.3. Randomly Distributed Coconut Coir Fibres Coated with Cashew Nut Shell

Liquid Oil as Reinforcement

The study on the soil reinforced with randomly distributed coconut coir fibres concluded with

the maximum strength characteristics observed at aspect ratio of 75 were added in 0.5% of

the dry weight of the soil. This combination was further examined by coating the coir fibres

in CSNL oil. The compressive strength increased by 4.41% from when untreated coir fibres

were used as reinforcement and by 100% from the unreinforced soil. The peak value was

attained at a higher strain percent, indicating an increase in the ductility of the sample.The

increase in strength when CNSL oil is used can be attributed to its binding characteristic. As

indicated by the images produced by analysing the sample under SEM, the oil causes a

development of an irregular coat on the fibre; this improves the adhesion between the treated

coir fibres with the soil which improves the cohesion of the modified soil.

Figure 13 Stress vs. Strain curve for soil soil reinforced with randomly distributed coir fibre coated

with CSNL Oil (UCS Test)

5. CONCLUSION

The study was undertaken to understand the nature of the locally available Lithomargic Clay

and propose soil modification techniques to improve its strength. The proposed soil

modifications were reinforcing the soil with randomly distributing untreated coconut coir

fibres and then by adding a coat of Cashew Nut Shell Liquid Oil on the fibres. The following

conclusions were drawn,

• With the use of coconut coir as reinforcement, a significant increase in the

strength characteristics of the soil was witnessed.

• As the aspect ratio and the fibre percent increased, a fall in the maximum dry

density was observed due to the replacement of soil with coir fibres of lower

specific gravity.

• For unconfined compressive strength of the modified soil, after an initial rise in

the value with the increase in the fibre percent for a particular aspect ratio, a fall in

the strength was observed. This can be attributed to the decrease in the quantity of

soil available for bond formation with the coir fibres.



• With untreated randomly distributed coir fibres as reinforcement, optimum

strength characteristics were obtained for an aspect ratio of 75 with 0.5% fibre at

dry weight of soil for unconfined compressive strength test .

• A further improvement in the strength parameters along with the ductility of the

modified soil was observed when the coconut coir fibres were coated with Cashew

Nut Shell Liquid oil.

REFERENCES

[1] Shankar Ravi A.U,Chandrasekhar A andBhatPrakash (2012). Experimental investigations

on lithomargic clay stabilized with sand and coir. The National Academies of Sciences, Engineering, and Medicine

[2] Manjunath R, .Vinay KS, Raghu R, NarunR, .Vibish PR. Stabiliazationof

Lithomargic Clay Using Sodium Chloride Salt

[3] Sarvade PG, Nayak S. (2012). Effect of Cement and Quarry Dust on Shear Strength and

Hydraulic Characteristics of Lithomargic Clay. Geotech GeolEng, Springer, 30:419–430

[4] Gregory Paul Makusa, (2012). Soil Stabilization Methods and Materials. Luleå University

of Technology, Luleå, Sweden

[5] Ali Majid. (2010) Coconut Fibre: A Versatile Material and Its Applications In

Engineering. International Conference on Sustainable Construction Materials (June)

[6] Maliakal T, Thiyyakkand S. (2012) Influence of Randomly Distributed Coir Fibers on

Shear Strength of Clay. Science + Buisness Media Dordrecht, Springer.

[7] Ramesh HN, Nanda, Manoj KV. Effect of Soaking on The Strength Behaviour Of Shedi

Soil treated with NFA.

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Documents

STRENGTH CHARACTERISTICS OF RANDOMLY DISTRIBUTED … · When added to the fibre reinforcements in the soil, it acts as a disinfectant, improving the durability of the material, while