international journal of science and engineering research ...coconut coir sodium chloride (nacl)...

International Journal of Science and Engineering Research (IJ0SER),

Vol 2 Issue 7 july-2014

Shahabas banu. . . . (IJ0SER) July- 2014

Experimental Investigation Of Soil Stabilization

shahabas banu.s M.E structural engineering

J.C.T College Of Engineering And Technology

Coimbatore, Tamilnadu,India.

*

Abstract— Clays exhibit generally undesirable engineering properties. They tend to have low shear strengths and to lose shear

strength further upon wetting or other physical disturbances. They can be plastic and compressible and they expand when wetted and

shrink when dried. Some types expand and shrink greatly upon wetting and drying – a very undesirable feature. Cohesive soils can

creep over time under constant load, especially when the shear stress is approaching its shear strength, making them prone to sliding.

They develop large lateral pressures. They tend to have low resilient modulus values. For these reasons, clays are generally poor

materials for foundations. The annual cost of damage done to non-military engineering structures constructed on expansive soils is

estimated as many billions of dollars worldwide. Many admixtures are successfully used for stabilizing expansive clays. The strength

characteristics of stabilized clays are measured by means of unconfined compressive strength (UCS) or California Bearing Ratio

(CBR) values. Depending upon the soil type, the effective admixtures content for improving the engineering properties of the soil is

varied.

Keywords— California Bearing Ratio, Cohesive soils, Proctor Compaction Test, specific gravity.

I. INTRODUCTION

Soil stabilization refers to the procedure in which a special

soil, a cementing material, or other chemical material is added

to a natural soil to improve one or more of its properties. One

may achieve stabilization by mechanically mixing the natural

soil and stabilizing material together so as to achieve a

homogeneous mixture or by adding stabilizing material to an

undisturbed soil deposit and obtaining interaction by letting it

permeate through soil voids. Where the soil and stabilizing

agent are blended and worked together, the placement process

usually includes compaction. Soil stabilizing additives are

used to improve the properties of less–desirable rood soils. When used these stabilizing agents can improve and maintain

soil moisture content, increase soil particle cohesion and serve

as cementing and water proofing agents.

A difficult problem in civil engineering works exists when

the sub-grade is found to be clay soil. Soils having high clay

content have the tendency to swell when their moisture

content is allowed to increase. Many research have been done

on the subject of soil stabilization using various additives, the

most common methods of soil stabilization of clay soils in pavement work are cement and lime stabilization. The high

strengths obtained from cement and lime stabilization may not

always be required, however, and there is justification for

seeking cheaper additives which may be used to alter the soil

properties.

A. OBJECTIVE

Soils are highly susceptible to volume and strength changes

and hence can cause severe roughness and accelerate the

detoriation of the pavement structure in the form of increased

cracking and decreased ride quality, when combined with

truck traffic. In some cases, the sub grade soils can be treated

with various materials to improve the strength and stiffness

characteristics of the soil.

This thesis investigates the potential of using

vegetable fiber such as coir in ground engineering

applications. In order to better understand the role of

reinforcing material (coir) in improving the strength sub grade pavement, an attempt is made in this

present study with the following objectives.

To find the most efficient way of using coir fibers to

reinforce the available soil sample, since its

environmental and financial advantages are

considerable.

Effect of change of percentage fiber content on the

engineering properties of compacted soil

II. REQUIREMENTS OF SOIL STABILISATION

Every stabilization process will be satisfactory when

it provides required qualities and fulfills the

following criteria:

(1) Be compactable with soil material

(2) Be permanent

(3) Be easily handled and processed

(4) Cheap and safe




A. MECHANICAL STABILISATION:

Mechanical stabilization involves two operations,

(a) Changing the composition of the soil by addition or

removal of certain constituents

(b) Densification or compaction

B. CEMENT STABILISATION:

The soil stabilized with Portland cement is known as soil

cement. The cementing action is believed to be result of

chemical reaction of cement with the silicous soil during

hydration. The binding action individual particles through

cement may be possible only in coarse – grained soils. In fine grained, cohesive soils, only some of the particles have

expected to have cement bonds, and rest will be bonded

through natural cohesion.

C. LIME STABILISATION

Hydrated (or slaked) lime is very effective

in treating heavy, plastic, clayey, soils. Lime may be used

alone or in combination with cement, bitumen, or fly ash.

Sandy soils can also be stabilized with these combinations.

Lime has been mainly used for stabilizing the road bases and sub- grades.

On addition of lime to soil, two main types

of chemical reactions occur:

(a) Alteration in the nature of the absorbed

layer through base exchange phenomenon

(b) Cementing or pozzolanic action.

III. STABILIZER

The admixtures that added to the soil to improve its

engineering performance are termed as stabilizers.

A. TYPES OF STABILIZERS

The types of stabilizers used are,

Coconut Coir

Sodium Chloride (NaCl)

Rice Husk Ash

B. COCONUT COIR

Coir is a natural fiber extracted from the husk of

coconut and used in products such as floor mats, doormats,

brushes, mattresses etc. Technically coir is the fibrous

material found between the hard, internal shell and the outer

coat of a coconut. Other uses of brown coir (made from ripe coconut) are in upholstery padding, sacking and horticulture.

White coir is harvested from unripe coconuts, and is used for

making finer brushes, string, rope and fishing nets.

Total world coir fiber production is 250,000 tonne (250,000

long tons; 280,000 short tons). The coir fiber industry is

particularly important in some areas of the developing world.

India, mainly in Pollachi 40% and the coastal region of Kerala

State, produces 20% of the total world supply of white coir

fiber. Sri Lanka produces annually throughout the world of

consumed in the countries of origin, mainly India. Together

India and Sri Lanka produce 90% of the 250,000 metric tons

of coir produced every year.

C PHYSICAL PROPERTIES OF COIR:

The physical appearance and quality of the fibers varies

widely. The color of the fiber is not influenced by the species

of the nut from which it is derived but also its maturity, time

lapse between dehusking and retting etc. However under identical conditions of these variables, the fibers extracted

from infant nuts exhibit a pale yellow color. The intensity of

color and thickness increase with age and the fibers are

remarkably stiff and posses good extensibility.

Morphologically, coir is a multi cellular fiber with 12 to 24

microns in diameter and the ratio of length to thickness is

observed to be 35.

D. SODIUM CHLORIDE

The stabilizing action of chloride is somewhat to that of calcium chloride, but it has not been so widely used. It attracts

and retains moisture and reduces the rate of evaporation.

Another beneficial phenomenon is the crystallization of the

salt in the soil pores near the surface, which retards further

evaporation and also reduces the formation of shrinkage

cracks.

E. RICE HUSK ASH

Rice Husk Ash (RHA) is obtained from the

burning of rice husk. The husk is a by-product of the rice milling industry. By weight, 10% of the rice grain is rice husk.

On burning the rice husk, about 20% becomes RHA

F. CHEMICAL COMPOSITION OF RICE HUSK ASH

Silica – SiO2 90.23%

Alumina – Al2O3 2.54%

Carbon 2.23%

Calcium Oxide – CaO 1.58%

Magnesium Oxide – MgO 0.53%

Potassium Oxide – KaO 0.39%

Ferric Oxide – Fe2O3 0.21%

G. SOIL SAMPLE

The soil sample is clay soil which is distributed in most of

the places around the coast of Bay of Bengal. A disturbed soil

sample is that in which a natural structure of soil get partly or

fully modified and is destroyed although with suitable

precautions for natural moisture content may be preserved.

Such a sample is called as representative soil sample. The representative soil sample for the thesis was collected

from a construction site near Pondicherry and it was analyzed

for its strength properties. An open pit was made up to a depth

of 1.5m below the ground surface where the representative

soil samples were taken.

http://en.wikipedia.org/wiki/Natural_fiber#Vegetable_fibers

http://en.wikipedia.org/wiki/Husk

http://en.wikipedia.org/wiki/Coconut

http://en.wikipedia.org/wiki/Coconut




H. LABORATORY EXPERIMENTS

The following laboratory experiments are performed as per

IS Specifications.

Specific Gravity

Sieve analysis (particle size distribution)

Atterberg’s limits (liquid limit, plastic limit)

Standard proctor compaction test (maximum dry

density and optimum moisture content)

Unconfined Compression Strength test.

III. EXPERIMENTAL INVESTIGATION

A. PARTICLE SIZE DISTRIBUTION OF VIRGIN SOIL SAMPLE

The dried sample is taken in a tray, soaked in water and

mixed with either 2g of sodium hexametaphosphate or 1g of

sodium hydroxide and 1g of sodium carbonate per liter of

water, which is added as a dispersive agent. The soaking of

soil is continued for 10 to 12hrs. The sample is washed

through 4.75mm IS Sieve with water till substantially clean

water comes out. Retained sample on 4.75mm IS Sieve should

be oven-dried for 24hrs. This dried sample is sieved through

20mm and 10mm IS Sieves.

Weight of Soil taken, g = 2000g

IS

Sieve

Particle

Size D

(mm)

Mass

retained

(g)

%

retained

Cumulative %

retained

%

finer

(N)

4.75 mm

4.75 1416 70.8 70.8 29.2

2.36

mm

2.36 144 7.2 78 22

1.18 mm

1.18 183 9.15 87.15 12.85

600 µ 0.6 118 5.9 93.05 6.95

300 µ 0.3 81 4.05 97.1 2.9

90 µ 0.09 42 2.1 99.2 0.8

75 µ 0.075 4 0.2 99.4 0.6

Pan Pan 12 0.6 100 0

B. SPECIFIC GRAVITY OF VIRGIN SOIL SAMPLE

Specific gravity is the ratio of the weight in air of a given

volume of a material at a standard temperature to the weight

in air of an equal volume of distilled water at the same stated

temperature

Weight of Soil taken, g = 500g

C. LIQUID LIMIT OF VIRGIN SOIL SAMPLE

Air-dry the soil sample and break the clods. Remove the

organic matter like tree roots, pieces of bark, etc. About 100g

of the specimen passing through 4.75mm IS Sieve is mixed

thoroughly with distilled water in the evaporating dish and left for 24hrs for soaking.

Natural water content, wt = 0.76%

Determination Trails

1 2 3

No. of blows 33 27 21

Container No. I II III

Wt of container (w0) g 19.15 19.23 19.73

Wt of container + wet soil (w1) g

25.83 35.74 36.12

Wt of container + oven dried soil (w2) g

23.01 28.7 29.02

Water content = (w1-w2)/(w2-w0) x 100%

73.06% 74.34% 76.43%

Water content 74.61%

D. PLASTIC LIMIT OF VIRGIN SOIL SAMPLE

Take out 30g of air-dried soil from a thoroughly mixed

sample of the soil passing through 4.75mm IS Sieve. Mix the soil with distilled water in an evaporating dish and leave the

soil mass for maturing.

Natural water content, wt = 0.76%

E. STANDARD PROCTOR COMPACTION TEST

Soil not susceptible to crushing during compaction a 5kg

sample of air-dried soil passing through the 19mm IS Sieve

should be taken. The sample should be mixed thoroughly

with a suitable amount of water depending on the soil type (for sandy and gravelly soil - 3 to 5% and for cohesive

soil - 12 to 16% below the plastic limit).

Specific Gravity of soil 1.952

Amount of compaction Light

Determinations Trails

1 2 3 Mass of pycnometer (M1) g 667

Mass of pycnometer + Dry soil (M2) g

1167 1167 1167

Mass of pycnometer + Soil + Water (M3) g

1800 1789 1812

Mass of pycnometer + Water (M4) g

1551 1562 1558

Specific Gravity G=(M2-M1)/[(M2-M1)-(M3-M4)]

1.992 1.832 2.033

Average Specific Gravity 1.952

Determination Trails

1 2 3

Container No. IV V VI

Wt of container (w0) g 21.7 20.15 22.37


29.41 28.38 31.59


26.6 25.4 28.2


57.35% 56.76% 58.15%

Water content 57.42%




Volume of the mould (V) cc 997.45 cc

Wt of the mould + Base plate (W1) 4.301 Kg

Fig. 1 optimum water content

Optimum moisture content by graph 20.49%

Maximum dry density by graph 1.713 g/cc

F. COMPACTION TEST OF SOIL AFTER ADDING COIR

The samples were prepared in dry condition by mixing

required quantity of coir fiber with soil. Coir fiber to be added

was worked out based on the dry weight of the soil.

1. COMPACTION TEST OF SOIL AFTER ADDING 0.5%

COIR

Fig. 2 optimum water content for adding 0.5% of coir


Maximum dry density by graph 2.485g/cc

2. COMPACTION TEST OF SOIL AFTER ADDING 1%

COIR

Fig. 3 optimum water content for adding 1 % of coir

Optimum moisture content by graph 22%


Determination Trail

1 2 3 4 5 6

Wt of mould +

Compacted soil (W2) Kg

5.982 6.089 6.17 6.218 6.28 6.351

Wt of compacted soil W, Kg

1.681 1.788 1.869 1.917 1.979 2.05

Wet density γb

= (W/V) g/cc

1.685 1.793 1.874 1.922 1.984 2.055

Water content (w) %

10% 12% 14% 16% 18% 20%

Dry density γd = γb/(1+w)

1.532 1.601 1.644 1.657 1.681 1.713

Dry density at zero voids, γd

= Gγw/(1+wG)

1.633 1.582 1.533 1.487 1.444 1.404

Determinati

on

Trails

1 2 3 4 5 6

Container No.

I II III IV V VI

Wt of container (w0) g

15.98 16.1 15.68

15.72

15.63

15.92


24.62 25.43

24.3 24.21

24.27

24.27


23.81 24.42

23.23

23.01

22.93

22.85


10.34%

12.14%

14.17%

16.46%

18.36%

20.49%





COIR

Fig. 4 optimum water content for adding 1.5% of coir



G. COMPACTION TEST OF SOIL AFTER ADDING NaCl


required quantity of NaCl with soil. NaCl to be added was

worked out based on the dry weight of the soil.The

representative soil is mixed with 10%, 15% and 20% of NaCl

and tests were conducted in laboratory.

1.COMPACTION TEST OF SOIL AFTER ADDING 10% NaCl

Fig. 5 optimum water content for adding 10% of NACL



2.COMPACTION TEST OF SOIL AFTER ADDING 15%

NaCl

Fig. 6 optimum water content for adding 15% of NACL



3.COMPACTION TEST OF SOIL AFTER ADDING 20%

NaCl

Fig. 7 optimum water content for adding 20 % of NACL



H. COMPACTION TEST OF SOIL AFTER ADDING RICE

HUSK ASH


required quantity of Rice husk ash with soil. Rice husk ash to

be added was worked out based on the dry weight of the soil.

The representative soil is mixed with 5%, 7.5% and 10% of

Rice husk ash and tests were conducted in laboratory.




1.

COMP

ACTI

ON TEST OF SOIL AFTER ADDING 5% RICE HUSK ASH




RICE HUSK ASH

Fig. 9 optimum water content for adding7.5% of ricehusk

3. COMPACTION TEST OF SOIL AFTER ADDING 10% RICE HUSK ASH

Fig. 10 optimum water content for adding7.5% of rice husk



I. UNCONFINED COMPRESSIVE STRENGTH

The initial length, diameter and weight of the specimen

shall be measured and the specimen placed on the bottom

plate of the loading device. The upper plate shall be adjusted

to make contact with the specimen. The deformation dial

gauge shall be adjusted to a suitable reading, preferably in multiples of 100.

Force shall be applied so as to produce axial strain at a rate

of 0.5 to 2 percent per minute causing failure with 5 to 10.

The force reading shall be taken at suitable intervals of the

deformation dial reading.

The angle between the failure surface and the horizontal

may be measured, if possible, and reported. The water content

of the specimen shall be determined in accordance with IS 2720 (Part 2): 1973 using samples taken from the failure zone

of the specimen.

TABLE I

FONT SIZES FOR PAPERS



Weight of sample 250g

Water content 20%

Diameter 38mm

Length 76mm

Area 1133.54 mm2

Deform

ation

dial

gauge

reading

1div=0.0

1mm

Defor

mation

ΔL

(mm)

Force

(F)

x103

N

Strain

∑=ΔL/

L

Area

A=A0/(

1-∑)

x103m

m2

Stress

(P/A)

N/mm2

50 0.2 1 0.0026 1.137 0.880

100 0.2 1 0.0026 1.137 0.880

150 0.3 1.5 0.0039 1.138 1.318

200 0.4 2 0.0053 1.140 1.755

250 0.5 2.5 0.0066 1.141 2.191

300 0.6 3 0.0079 1.143 2.626

350 0.7 3.5 0.0092 1.144 3.059

400 0.9 4.5 0.0118 1.147 3.923

450 1 5 0.0132 1.149 4.353

500 1.2 6 0.0158 1.152 5.210

550 1.3 6.5 0.0171 1.153 5.636

600 1.5 7.5 0.0197 1.156 6.486

650 1.6 8 0.0211 1.158 6.909

700 1.8 9 0.0237 1.161 7.752

750 2 10 0.0263 1.164 8.590

UCC strength of the sample 4.104 N/mm2

Unit Cohesion, c 4.295 N/mm2




A. UCC STRENGTH OF SOIL AFTER ADDING COIR


required quantity of coir fiber with soil. Coir fiber to be added

was worked out based on the dry weight of the soil. The

samples for unconfined compression test, consists of coir fiber mixed in dry soil and compacted at optimum moisture content

(OMC) found out by conducting Standard Proctor compaction

Test under varying percentages of coir. The representative soil

is mixed with 0.5%, 1% and 1.5% of coir fiber and tests were

conducted in laboratory.

1. UCC STRENGTH OF SOIL AFTER ADDING 0.5% COIR

Water content =22%

2. UCC STRENGTH OF SOIL AFTER ADDING 1% COIR

3. UCC STRENGTH OF SOIL AFTER ADDING 1.5% COIR



B. UCC STRENGTH OF SOIL AFTER ADDING NaCl

The samples were prepared in dry condition by

mixing required quantity of NaCl with soil. NaCl to be added

was worked out based on the dry weight of the soil. The

representative soil is mixed with 10%, 15% and 20% of NaCl

and tests were conducted in laboratory.

1. UCC STRENGTH OF SOIL AFTER ADDING 10% NaCl

Water content =12%













Unit Cohesion, c 4.919N/mm2

C.UCC STRENGTH OF SOIL AFTER ADDING RICE HUSK

ASH

The samples were prepared in dry condition by

mixing required quantity of Rice husk ash with soil. Rice husk ash to be added was worked out based on the dry weight of

the soil. The samples for unconfined compression test,

consists of Rice husk ash mixed in dry soil and compacted at

optimum moisture content (OMC) found out by conducting

Standard Proctor compaction Test under varying percentages

of Rice husk ash. The representative soil is mixed with 5%,

7.5% and 10% of Rice husk ash and tests were conducted in

laboratory.

1. UCC STRENGTH OF SOIL AFTER ADDING 5% RICE

HUSK ASH

Water content =12%



2. UCC STRENGTH OF SOIL AFTER ADDING 7.5% RICE HUSK ASH

3. UCC STRENGTH OF SOIL AFTER ADDING 10% RICE

HUSK ASH










IV. RESULT

TEST COMPARISONS

COMPACTION FACTOR TEST

G. COMPACTION TEST

The relation between dry density and moisture

content for different stabilizers (rice husk ash,

coconut coir, common salt) are plotted.

The addition of stabilizers to the soil increased the

dry density and optimum moisture content of soil.

H. UNCONFINED COMPRESSIVE STRENGTH

II. CONCLUSIONS

UNCONFINED COMPRESSION TEST

The unconfined compressive stress-strain

relationships of specimens, with different

stabilizers and different moisture percentages are

plotted. The unconfined compressive strength increase

with the increase in the compaction effort and

addition of stabilizers.

TEST REPORT




By the addition of stabilizers alters the properties

of the sample.

The strength increases with increase in the

percentage of stabilizers.

The addition of coconut coir to the soil causes

hardening and more strength as compared to the

other additives.

REFERENCES

A. Books And Is-Codes

[1] B.C.Punmia &Ashok K. Jain, “Soil Mechanics and Foundation

Engineering” Laxmi Publications..

[2] “Ground Improvement Techniques” S.Purusothama Raj, Laxmi

Publications

[3] Indian Standards METHODS OF TEST FOR SOILS (Second

Revision) IS: 2720 (Part 1 to Part 41) - 1983, Indian Standards

Institution, April 1984, New Delhi.

[4] Indian Standards METHODS OF TEST FOR STABILIZED IS: 4332

(Part 2 to Part 10) - 1967, Indian Standards Institution, January 1968,

New Delhi.

[5] Indian Standards GLOSSARY OF TERMS AND SYMBOLS (First

Revision) IS: 2809 - 1972, Indian Standards Institution, September

1972, New Delhi.

[6] National Building Code.

shahabas banu She is percusing M.E structural engineering in J.C.T college of Engg. & Tech., Coimbatore. She completed her B.E.(civil) in Nehru institute of technology, Coimbatore

international journal of science and engineering research ...coconut coir sodium chloride (nacl)...

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