Experimental Investigation on Black Cotton Soil Using Bio

Experimental Investigation on Black Cotton Soil

Using Bio-Enzyme as a Soil Stabilizer in

Road Construction S.P.Kanniyappan

1, R.G.Dhilip Kumar

2, A.Faizuneesa

3, S.Saranya

4

1, 2, 3, 4 Assistant Professor, Department of Civil Engineering, R.M.K Engineering College, Kavaraipettai, Tamilnadu

[email protected]

Abstract — Bio-enzyme is a natural, non-toxic, non-flammable, non-corrosive liquid enzyme formulation fermented from

vegetable extracts that improves the engineering qualities of soil, facilitates higher soil compaction densities and increases stability.

Enzymes catalyse the reactions between the clay and the organic cat-ions and accelerate the cat-ionic exchange process to reduce

adsorbed layer thickness. In this study, Black cotton soil with varying index properties have been tested for stabilization process and

strength of the stabilized soil were evaluated after the curing period of 7 days & 14 days for various enzyme dosages 200 ml/3m3,

200 ml/2.5m3, 200ml/2m3, 200ml/1.5m3. The tests which were carried out are the California Bearing Ratio (CBR) test and Unconfined

Compressive strength (UCS) test for the soil specimen. The test results indicates that bio-enzyme stabilization improves the strength

of Black Cotton soil up to great extent, which indicate the bearing capacity and the resistance to deformation increases in stabilized

soil. Adopting the IRC method, based on soil CBR, the pavement design thickness on stabilized soil also reduces 25 to 40%.

Keywords — Black Cotton Soil, Compressive Strength, California Bearing Ratio, Shear Strength, Terrazyme, Unconfined

Compressive Strength

I. INTRODUCTION

A. General

The process of improving the strength and durability of soil is known as soil stabilization. The main aim of stabilization is

cost reduction and to efficiently use the locally available material. Most common application of stabilization of soil is seen in

construction of roads and airfields pavement. Chemical stabilization is done by adding chemical additives to the soil that

physically combines with soil particles and alter the geotechnical properties of soil. Enzymes enhance the soil properties and

provide higher soil compaction and strength.

Terrazyme is non-toxic, non-corrosive and inflammable liquid which can be easily mixed with water at the optimum

moisture content and improves the properties of soil and strength of soil significantly. Life of a structure increases as CBR

value is increased and consistency limits are decreased. The chemical bonding of the soil particles is increased by the use of

Terrazyme and a permanent structure is formed which is resistant to wear and tear, weathering and infiltration of water in soil.

Apart from improving strength of soil, this bio enzyme replaces the need of granular base and sub base. Terrazyme dosage

entirely depends on the type of soil, clay content and plasticity index of soil. Different parameters were considered in the

present work to check the effects of Terrazyme on local soil. Sub-grade soil is an important material in highway construction.

In general practice locally available material is used as sub-grade soil. In some cases, the local material does not have sufficient

strength to bear the estimated loads. Such soils which do not possess sufficient strength can be stabilized using various

additives like lime, cement etc.

Soil improvement is a combination of physical and chemical methods for improving the characteristics of soil when it is

used as a construction material. Pozzolana material like fly ash can also be used as soil stabilizer. The materials like fly ash are

not easily available in every area. If fly ash is transported from distant places, transportation cost increases. An ideal soil

stabilizer should be easily available, economical and eco-friendly. Terrazyme is a good alternative to the conventional soil

stabilizers like fly ash, lime etc. Terrazyme is a bio-enzyme which is used as a soil stabilizer in construction of road

infrastructure. It is used to improve the soil properties. It is non-toxic and natural substance. It is formulated from plants,

vegetable extract and fruit extract. So it is also ecofriendly. In the present study, effect of addition of Terrazyme for improving

CBR value of soil is analyzed.

ISSN NO: 0975-6876

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B. Bio-Enzymatic Soil Stabilization

1) About Bio-enzyme

Bio-enzyme is a natural, non-toxic, non-flammable, non-corrosive liquid enzyme formulation fermented from

vegetable extracts that improves the engineering qualities of soil, facilitates higher soil compaction densities, and increases

stability. Enzymes catalyse the reactions between the clay and the organic cat-ions and accelerate the cat-ionic exchange

process to reduce adsorbed layer thickness. For other types of chemical stabilization, chemicals are mixed with soil, which is

difficult to mix thoroughly, but Bio-enzyme is easy to use as it can be mixed with water at optimum moisture content and then it

is sprayed over soil and compacted.

2) Mechanism of soil stabilization by bio-enzyme

In clay water mixture positively charged ions (cat-ions) are present around the clay particles, creating a film of water

around the clay particle that remains attached or adsorbed on the clay surface. The adsorbed water or double layer

gives clay particles their plasticity.

In some cases the clay can swell and the size of double layer increases, but it can be reduced by drying. Therefore to

truly improve the soil properties, it is necessary to permanently reduce the thickness of double layer.

In the present study, one type of bio-enzyme has been used for stabilization of five types of soil with varying index

properties. Detailed laboratory tests were carried out to ascertain the benefits in terms of reduction in design thickness.

Cat-ion exchange processes can accomplish this. By utilizing fermentation processes specific micro-organisms can

produce stabilizing enzyme in large quantity. These soil stabilizing enzymes catalyse the reactions between the clay

and the organic cat-ions and accelerate the cat-ionic exchange without becoming part of the end product.

3) Bio-enzyme as soil stabilizer in road construction

Cost effective roads are very vital for economic growth in any country. There is an urgent need to identify new

materials and to improve road construction techniques to expand the road network. Commonly used materials are fast depleting

and this has led to an increase in the cost of construction. Hence, the search for new materials and improved techniques to

process the local materials has received an increased impetus. When poor quality soil is available at the construction site, the

best option is to modify the properties of the soil so that it meets the pavement design requirements. This has led to the

development of soil stabilization techniques. Since the nature and properties of natural soil vary widely, a suitable stabilization

technique has to be adopted for a particular situation after considering the soil properties. Soil improvement by mechanical or

chemical means is widely adopted. In order to stabilize soils for improving strength and durability, a number of chemical

additives, both inorganic and organic, have also been used. Recently bio-enzymes have emerged as a new chemical for soil

stabilization. Bio- enzymes are chemical, organic, and liquid concentrated substances which are used to improve the stability of

soil sub-grade for pavement structures. Bio-Enzyme is convenient to use, safe, effective and dramatically improves road quality.

4) Enzyme stabilization effects

Organic cat-ions generated by the growth of vegetation and microorganisms also have the capability to exchange

position with other ions attracted to the clay platelet in the soil. In contrast with metal cat-ions, the organic cat-ions have large

flat structures that approach the size of small clay particles. These organic cat-ions can blanket the clay particle and effectively

neutralize its negative charge in a short distance, thus greatly reducing the double layer thickness. Certain soil microorganisms

make use of this chemistry to stabilize their environment. They produce specific enzymes that catalyse the reactions between

the clays and the organic cat-ions, producing clods of stable soil among the roots of the vegetation. These soil-stabilizing

enzymes accelerate the cationic exchange without becoming part of the end product.

By utilizing fermentation processes, specific microorganisms can produce stabilizing enzymes in large quantities. This

fermentation, formulated products are non-toxic and environmentally harmless. When exposed to the air, the microorganisms

multiply rapidly and produce large organic molecules, which the enzyme attaches to the clay platelets. The negative charges on

the clay platelets are neutralized through this process and the size of the electrical double layer shrinks. This limits further

adsorption of water or the resultant swelling with loss of density. The enzyme is regenerated by the reaction and goes on to

perform again. Reactions, which might otherwise take years to occur, can be carried out in weeks. While some soil strength

gain will become apparent within days, field research indicates that strength will continue to increase over a period of several

weeks. As the soil is exposed to air and the reaction proceeds, water, which was initially adsorbed on, the clay will be released

from the clay structure and can evaporate. As this occurs, clay particles are drawn closer together, soil density increases and the

load bearing structure strengthens.

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Terrazyme soil stabilization products are also designed to improve soil strength by increasing the density of initial

compaction and facilitating the removal of pore water, which minimizes the destructive impact of water under conditions of

loading. Combined with the impact of Terrazyme on the electrical double layer of clay particles, these factors can promote the

formation of a stabilized soil structure of superior density and load bearing strength even in soils lacking a significant plastic

fines fraction. Field results indicate that soil treated with Terrazyme can reach 95% Modified Proctor with significantly reduced

compaction effort.

Compacting of the soil at the optimum moisture content using proper construction methods and equipment is essential

to produce the high density necessary for enzymatic stabilization. The reduction in voids resulting from this realignment would

decrease pore water within the treated road layer and inhibit water penetration. This impact of the Terrazyme treatment Process

on the soil structure correlates with observed reductions in permeability. All of the factors discussed can combine to minimize

the destructive impact of soil water on the load bearing structure of the treated layer. Because the organic ions are very large,

little migration takes place within the pore water. Therefore, to achieve the desired results, intimate mixing is required to

distribute the enzyme solution throughout the soil. In addition, compaction of the soil at the optimum moisture content using

proper construction methods and equipment is essential to produce the high density necessary for enzymatic stabilization. Close

adherence to all aspects of the Terrazyme treatment process is important to soil stabilization success.

C. Scope of the Present Study

Enzymes catalyze the reactions between the clay and the organic cat-ions and accelerate the cationic exchange process to

reduce adsorbed layer thickness. For other types of chemical stabilization, chemicals are mixed with soil, which is difficult to

mix thoroughly, but bio-enzyme is easy to use as it can be mixed with water at optimum moisture content and then it is sprayed

over soil and compacted. In this study Black cotton soil with various qualities, index properties will be test for stabilization

process and strength of the stabilized soil will be evaluated after the curing period of 7 days &14 days for various enzyme

dosages of 1%, 2%, 3% and 4% of 200ml/3m3.

D. Objectives of the Present Study

To study the experimental output by doing stabilization tests.

To study the effect of Bio-enzyme on the quality of sub grade/base course layers and its influence on pavement system.

To optimize the quantity of Bio-enzyme to be used as stabilizing agent and the extent of stabilization of strength gain

with time.

II. METHODOLOGY, MATERIALS USED & ITS PROPERTIES

A. Methodology

The total study is carried out in two stages. In the first stage, the soil characterization is done. In the second stage,

Terrazyme is added to the soil in two dosages, 0.05% and 0.1% and studies are conducted. Tests are conducted with soil alone

as well as soil stabilized with terrazyme containing different dosages. The soil is oven dried and pulverized then mixed with the

desired amount of terrazyme. Water is added to the mixture and mixed until it becomes homogenous. The laboratory tests

carried out on the natural soil include particle size distribution as per IS: 1498-1970, Specific Gravity as per IS: 2720 Part III

section 1-1980, Atterbergs limits test as per IS: 2720-part V 1985, Compaction test as per IS: 2720 part VII-1980, Unconfined

compressive strength test as per IS: 2720-part X. CBR tests as per IS: 2720 part XVI. Unconfined compression tests are

conducted on soil and terrazyme mixes compacted at their respective Maximum Dry Density (MDD) and Optimum Moisture

Content (OMC).

B. Materials

1) Black cotton soil

Black Cotton Soil (BC Soil) is a highly clayey soil. The black colour in Black cotton soil is due to the presence of titanium

oxide in small concentration as shown in Fig 1. The Black Cotton Soil (BC Soil) has a high percentage of clay, which is

predominantly montmorillonite in structure and black or blackish grey in colour. Expansive soils are the soils which expand

when the moisture content of the soils is increased. The clay mineral montmorillonite is mainly responsible for expansive

characteristics of the soil. The expansive soils are also called swelling soils or black cotton soils.

2) Terrazyme

Bio-enzyme from Australia is a natural, nontoxic bio-degradable liquid concentrate as shown in Fig 2 that mixes easily in

water for application with standard water spraying equipment. Bio-Enzyme is a low cost additive with long lasting effects.

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By altering the physical and chemical characteristics of soil, materials treated with Bio-Enzyme retain higher performance

levels and extended life span. Bio-Enzyme may be used to increase the Maximum dry density and Unconfined Compressive

Strength (UCS) values of a marginal material to achieve specified standards for a base course.

Fig. 1 Black Cotton Soil Fig. 2 Terrazyme

C. Properties of Terrazyme

TABLE I PROPERTIES OF TERRAZYME

Colour Dark brown

PH 3.50

Evaporation Rate Same as water

Odour Smells like Molasses

Extracted from Molasses

Specific Gravity 1.414

III. EXPERIMENTAL INVESTIGATION & TEST RESULTS

A. California Bearing Ratio (CBR) Test

CBR is California Bearing Ratio, defined as the ratio of force per unit area required to penetrate a soil mass with standard

circular piston that requires for the corresponding penetration of standard material. This test is usually needed to determine the

sub-grade strength of the soil in pavements. With the addition of Terrazyme a significant increase in the values of both soaked

and unsoaked CBR samples is seen. This is because of the increased compaction which creates a stronger bond between the soil

particles, helping them to resist penetration more appreciably. Also with the increase in curing period of samples with

Terrazyme, it is seen that the CBR value increases, indicating more strength provided by the soil with time.

B. Unconfined Compressive Strength (UCS)Test

UCS is the maximum axial compressive stress of a right cylindrical sample of soil or any other material can withstand under

unconfined (confining stress is zero) conditions. UCS test basically gives the strength of the soil so to determine the effect of

Terrazyme it is necessary to know the changes on UCS. After performing various tests on different types of soils it is seen that

with the addition of Terrazyme there is an increase in the unconfined compressive strength of soil to a great extent. In some

cases, UCS has increased as much as 200% making the enzyme an ideal solution for soil stabilization.

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1) Experimental Results of Black Cotton Soil without Bio-Enzyme

a) California Bearing Ratio (CBR) Test Observations

TABLE II

CBR TEST WITHOUT BIO-ENZYME

Sl. No. Penetration (mm) Proving Ring Divisions Load (Kg)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

6.0

7.0

8.0

9.0

12

32

50

56

60

64

66

67

70

71

71

72

73

74

14.40

38.42

60.03

67.23

72.04

76.84

79.24

80.44

84.04

85.24

85.24

86.45

87.65

88.85

Calculation of CBR corresponding to 2.5mm & 5mm penetration using the relation,

CBR = (Test Load/Standard Load) ×100

Penetration (mm) Standard Load (Kg)

2.5 1370

5.0 2055

Fig. 3 Graph between Penetrations (mm) Vs. Load (Kg)

CBR @ 2.5mm = 5.25%

CBR @ 5.0mm = 4.14%

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b) Unconfined Compression Strength (UCS) Test Observations

TABLE III

UCS TEST WITHOUT BIO-ENZYME

Proving Ring Load = 0.2674

Initial Diameter of Mould = 3.4 Cm

Length of the Mould = 7.0 Cm

Compressive Strength (qu) = 0.94 kg/cm2

Shear Strength = qu/2 = 0.472 kg/cm2

Fig. 4 Graph between Strain and Stress (Kg/cm2)

c) Properties of Black Cotton Soil without Bio-Enzyme

TABLE IV

PROPERTIES OF BC SOIL

Sl. No. Property Result

1 Dry Density 1.46 g/cc

2 Optimum Moisture Content 30 %

3 Liquid Limit 76 %

4 Plastic Limit 43.62

5 CBR

Un Soaked

Soaked

5.25 %

0.74 %

6 Unconfined Compressive Strength 0.944 kg/cm2

7 Soil Classification CH (High Compressible Inorganic Clay)

Divisions (∆L)

mm

Proving

Divisions

Load Strain

e=∆L/L0

Area

A=A0/(1-e) cm2

Stress

P/A

Kg/cm2

50

100

150

200

250

300

350

400

450

500

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

16

21

24

26

28

30

31

34

34

34

4.28

5.61

6.42

6.95

7.49

8.02

8.29

9.09

9.09

9.09

0.007

0.014

0.021

0.028

0.036

0.042

0.050

0.057

0.064

0.071

9.144

9.209

9.274

9.341

9.419

9.478

9.558

9.628

9.700

9.773

0.468

0.609

0.692

0.744

0.795

0.846

0.867

0.944

0.937

0.930

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Terrazyme stabilization has shown little to very high improvement in physical properties of soils. This little

improvement may be due to chemical constituent of the soil, which has low reactivity with Bio-enzyme. Therefore, it is

advisable to first examine the effect of Bio-enzyme on soil stabilization in the laboratory before actual field trials. In some cases

where the soil is very weak like highly clay to moderate soil, like silty soil to sandy soil, the effect of stabilization has improved

the CBR and unconfined compression strength.

d) Dosage of Enzyme

The Terrazyme dosage for 200ml/3m3

soils varies for 1%, 2%, 3% and 4%. The Enzyme dosage is calculated as

follows:

Bulk Density of Black Cotton Soil = 1.46 g/cc

Bulk Density = Weight/Volume

Weight = Bulk Density ×Volume

= 1.46×3.0×1000

= 4380 Kg

Therefore, Consider 5Kg Soil Sample,

For 1% Terrazyme dosage = (1/5000) ×100 = 0.02 ml

2% Terrazyme dosage = (2/5000) ×100 = 0.04 ml



Dosage (%) Terrazyme (ml)

1

2

3

4

0.02

0.04

0.06

0.08

2) Experimental Results of Black Cotton Soil with Bio-Enzyme

To know the Strength and Durability of Black Cotton Soil with Bio-Enzyme, Unconfined Compression Strength (UCS)

Test and California Bearing Ratio (CBR) Test is conducted.

a) Unconfined Compressive Strength (UCS) Test Observation & Results

Unconfined Compression Test is conducted with various Terrazyme dosages of 1%, 2%, 3% and 4% with 7 days

and 14 days curing period.

The Unconfined Compression Test results is as follows for 7 days curing period with various dosages of Terrazyme,

Dimensions of the mould:

Length of the mould (L) = 7 cm

Diameter of the mould (D) = 3.4 cm

Area of the mould (Ao) = 9.08 cm2

For 1% Dosage 7 Days Curing:

Observations:

TABLE V UCS (1%) 7 DAYS

Divisions (∆L) mm Proving

Divisions Load

Strain

e=∆L/L0

Area

A=A0/(1-e) cm2

Stress

P/A Kg/cm2

50

100

150

200

250

0.5

1.0

1.5

2.0

2.5

70

134

149

168.5

143

18.72

35.83

39.84

45.06

38.24

0.007

0.014

0.021

0.029

0.035

9.144

9.209

9.274

9.341

9.419

2.047

3.890

4.295

4.824

4.059

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Fig. 5 UCS (1%) graph after 7 days curing

Result:



Shear Strength is increased from 0.472 kg/cm2 to 2.412 kg/cm

2


Observations:

TABLE VI

UCS (2%) 7 DAYS

Divisions (∆L) mm Proving

Divisions Load

Strain

e=∆L/L0

Area

A=A0/(1-e) cm2

Stress

P/A Kg/cm2

50

100

150

200

250

0.5

1.0

1.5

2.0

2.5

68

116

146

174

174

18.18

31.02

39.04

46.52

46.52

0.007

0.014

0.021

0.029

0.035

9.144

9.209

9.274

9.341

9.419

1.988

3.368

4.234

4.980

4.941


Result:




2

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Observations:

TABLE VII

UCS (3%) 7 DAYS

Divisions (∆L)

mm

Proving

Divisions Load

Strain

e=∆L/L0

Area

A=A0/(1-e) cm2

Stress

P/A

Kg/cm2

50

100

150

200

250

300

350

0.5

1.0

1.5

2.0

2.5

3.0

3.5

38

95

127

184

228

222

215.5

10.16

25.403

33.96

49.201

60.96

59.36

57.62

0.007

0.014

0.021

0.029

0.035

0.043

0.050

9.144

9.209

9.274

9.341

9.419

9.478

9.558

1.111

2.758

3.662

5.267

6.472

6.263

6.02


Result:




2


Observations:

TABLE VIII UCS (4%) 7 DAYS

Divisions (∆L)

mm

Proving

Divisions Load

Strain

e=∆L/L0

Area

A=A0/(1-e) cm2

Stress

P/A

Kg/cm2

50

100

150

200

250

0.5

1.0

1.5

2.0

2.5

32

87

150

282

282

8.55

23.26

40.11

75.41

75.41

0.007

0.014

0.021

0.029

0.035

9.144

9.209

9.274

9.341

9.419

0.935

2.525

4.325

8.073

8.006

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Result:




2

The Unconfined Compression Test results is as follows for 14 days curing period with various dosages of Terrazyme,


Observations:

TABLE IX UCS (1%) 14 DAYS

Divisions (∆L)

mm

Proving

Divisions Load

Strain

e=∆L/L0

Area

A=A0/(1-e) cm2

Stress

P/A

Kg/cm2

50

100

150

200

250

300

0.5

1.0

1.5

2.0

2.5

3.0

20

35.8

75.2

90.2

110.2

105.00

5.35

9.57

20.11

24.12

29.47

28.77

0.007

0.014

0.021

0.029

0.035

0.043

9.144

9.209

9.274

9.341

9.419

9.478

0.585

1.039

2.168

2.583

3.128

3.035


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Result:




2


Observations:

TABLE X UCS (2%) 14 DAYS

Divisions (∆L)

mm

Proving

Divisions Load

Strain

e=∆L/L0

Area

A=A0/(1-e) cm2

Stress

P/A

Kg/cm2

50

100

150

200

250

300

0.5

1.0

1.5

2.0

2.5

3.0

52

76

126

190

244

240

13.904

20.322

33.692

50.806

65.245

64.176

0.007

0.014

0.021

0.029

0.035

0.043

9.144

9.209

9.274

9.341

9.419

9.478

1.520

2.206

3.633

5.439

6.927

6.771

Fig. 10 UCS (2%) graph after 14 days curing Result:




2


Observations:

TABLE XI

UCS (3%) 14 DAYS

Divisions (∆L)

mm

Proving

Divisions Load

Strain

e=∆L/L0

Area

A=A0/(1-e) cm2

Stress

P/A

Kg/cm2

50

100

150

200

250

300

0.5

1.0

1.5

2.0

2.5

3.0

80

101

172

226

342

342

21.39

27.00

45.99

60.43

91.45

91.45

0.007

0.014

0.021

0.029

0.035

0.043

9.144

9.209

9.274

9.341

9.419

9.478

2.339

2.932

4.959

6.469

9.995

9.649

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Result:




2


Observations:

TABLE XII

UCS (4%) 14 DAYS

Divisions (∆L)

mm

Proving

Divisions Load

Strain

e=∆L/L0

Area

A=A0/(1-e) cm2

Stress

P/A

Kg/cm2

50

100

150

200

250

300

350

400

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

98

144

226

294

382

450

496

492

26.205

38.506

60.434

78.616

102.147

120.330

132.630

131.561

0.007

0.014

0.021

0.029

0.035

0.043

0.050

0.058

9.144

9.209

9.274

9.341

9.419

9.478

9.558

9.628

2.866

4.181

6.516

8.416

10.845

12.695

13.876

13.66


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Result:




2

b) California Bearing Ratio (CBR) Test Observation & Results

California Bearing Ratio Test is conducted with various Terrazyme dosages of 1%, 2%, 3% and 4% with a 7 days

curing period.

The California Bearing Ratio Test results is as follows for 7 days curing period with various dosages of Terrazyme,


Observations:

TABLE XIII CBR (1%) 7 DAYS


1

2

3

4

5

6

7

8

9

10

11

12

13

14

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

7.0

8.0

25

53

74

88

106

119

130

137

146

152

156

158

160

160

30.02

63.67

88.85

105.66

127.27

142.88

156.09

164.49

175.30

182.51

187.31

189.71

192.11

192.11

CBR @ 2.5mm = (127.77/1370) × 100 = 9.28%

CBR @ 5.0mm = (182.51/2055) × 100 = 8.88%

Fig. 13 CBR (1%) graph after 7 days curing

Result:

CBR for 1% = 9.28%

Percentage of CBR value increased = ((9.28-5.25)/5.25)×100 = 76.76%

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Observations:

TABLE XIV

CBR (2%) 7 DAYS


1

2

3

4

5

6

7

8

9

10

11

12

13

14

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

7.0

8.0

17

30

52

76

112

120

133

148

160

163

168

172

179

184

20.411

36.021

62.436

91.253

134.478

144.089

159.693

177.704

192.112

195.714

201.717

206.520

214.925

220.928

CBR @ 2.5mm = (134.478/1370) × 100 = 9.81%

CBR @ 5.0mm = (195.714/2055) × 100 = 9.53%


Result:

CBR for 2% = 9.81%


ISSN NO: 0975-6876





Observations:

TABLE XV

CBR (3%) 7 DAYS


1

2

3

4

5

6

7

8

9

10

11

12

13

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

7.0

32

65

8

124

131

137

142

146

148

160

179

196

196

38.422

78.045

105.661

148.886

157.291

164.495

170.499

175.302

177.704

192.112

214.925

235.337

235.337

CBR @ 2.5mm = (157.291/1370) × 100 = 11.44%

CBR @ 5.0mm = (177.704/2055) × 100 = 9.35%


Result:

CBR for 3% = 11.44%


ISSN NO: 0975-6876





Observations:

TABLE XVI

CBR (4%) 7 DAYS


1

2

3

4

5

6

7

8

9

10

11

12

13

14

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

7.0

8.0

43

81

127

166

198

230

255

272

284

293

317

317

324

337

51.630

97.267

152.485

199.316

237.738

276.161

306.178

326.590

340.998

351.805

380.621

380.621

389.026

404.635

CBR @ 2.5mm = (237.738/1370) × 100 = 17.35%

CBR @ 5.0mm = (351.805/2055) × 100 = 17.11%


Result:

CBR for 4% = 17.35%


ISSN NO: 0975-6876




c) Consolidated Test Results

1) Unconfined Compression Strength (UCS) Test Results TABLE XVII

UCS TEST RESULTS

Dosage of

Terrazyme (%)

UCS Value

7 Days

UCS Value

14 Days

1

2

3

4

2.412

2.490

3.123

4.036

1.564

3.384

4.998

6.830

2) California Bearing Ratio (CBR) Test Results TABLE XVIII

CBR Test Results

Dosage of

Terrazyme (%)

CBR Value

(7 Days) % Increased

1

2

3

4

9.28

9.81

11.44

17.35

76.76

86.87

118.00

230.47

IV. CONCLUSIONS

The addition of Terrazyme increases the CBR Value and UCS Value of the Black Cotton Soil consistently when there

is an increase in the dosage of the Terrazyme and it is being cured for several days and also the cost of the pavement is reduced

by using Terrazyme as an admixture. The pavement construction value is reduced by 30% of the total cost with the help of this

Bio-Enzyme. As a result of soil stabilization, the bearing capacity of the foundation of the structure is increased and its strength,

water tightness, resistance to washout, and other properties are improved. Soil stabilization is widely used in the construction on

sagging soils of industrial and civil buildings.

Terrazyme stabilization has shown little to very high improvement in physical properties of soils. This little

improvement may be due to chemical constituent of the soil, which has low reactivity with Bio-enzyme. Therefore, it is

advisable to first examine the effect of Bio-enzyme on soil stabilization in the laboratory before actual field trials. In some cases

where the soil is very weak like highly clay to moderate soil, like silty soil to sandy soil, the effect of stabilization has improved

the CBR and unconfined compression strength.

Pavement design thickness also reduces to 25 to 40 percent. Moreover, in case of scarcity of granular material, only

stabilized surface with thin bituminous surfacing can fulfil the pavement design requirement with more than 10 percent saving

in cost component.

REFERENCES

[1] Rajoria, Vijay and Suneet Kaur, “A Review on Stabilization of Soil Using Bio-Enzyme", International Journal of Research in Engineering and Technology, 1999.

[2] Isaac, P.Kuncheria, P.B.Biju and A.Veeraragavan, "Soil Stabilization using Bio-enzymes for Rural Roads", Seminar on Integrated Development of Rural

and Arterial Road Network for Socio-Economic Growth, New Delhi, Vol. 2 - 2003. [3] Marasteanu and O.Mihai, "Preliminary laboratory investigation of enzyme solutions as a soil stabilizer", 2005.

[4] Naagesh, Sureka and S.Gangadhara, "Swelling properties of bio-enzyme treated expansive soil", International Journal of Engineering Studies, P.No.155-

159, 2010. [5] C.Venkatasubramanian and G.Dhinakaran, "Effect of Bio-Enzymatic Soil Stabilization on and Applied Sciences”, P.No.295-298, 2011.

[6] Agarwal, Puneet, and Suneet Kaur, "Effect of Bio-Enzyme Stabilization on Unconfined Compressive Strength of Expansive Soil", International Journal of

Research in Engineering and Technology, 2014. [7] S.M.Lim, D.C.Wijeyesekera, A.J.M.S.Lim and I.B.H.Bakar, “Critical Review of Innovative Soil Road Stabilization Techniques”, International Journal of

Engineering and Advanced Technology, June 2014.

[8] Purnima Bajpai, “Non - Conventional soil stabilization techniques the way forward to an aggregate free pavement and a cost effective method of road construction”, International Journal of Scientific & Engineering Research, June 2014.

[9] Kavish S.Mehta, Rutvij J.Sonecha, Parth D.Daxini, Parth B.Ratanpara, Kapilani S.Gaikwad, “Analysis of Engineering Properties of Black Cotton Soil &

Stabilization Using By Lime”, International Journal of Engineering Research and Applications, May 2014. [10] Saini, Venika and Priyanka Vaishnava, "Soil Stabilization by using Terrazyme", International Journal of Advances in Engineering & Technology 2015.

[11] Joydeep Sen and Jitendra Prasad Singh, “Stabilization of black cotton soil using bio enzyme for a highway material”, International Journal of Innovative

Research in Science, Engineering and Technology 2015. [12] Swathy M Muraleedharan and Niranjana K, “Stabilization of Weak Soil using Bio-Enzyme”, International Journal of Advanced Research Trends in

Engineering and Technology, March 2015.

ISSN NO: 0975-6876




Documents

Experimental Investigation on Black Cotton Soil Using Bio