Blac Cotton Soil

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Study of Geotechnical properties of black cotton soil contaminated

by castor oil and stabilization of contaminated soil by sawdust

Ms. Arpita V Patel

Asst. Professor, Department of Civil Engineering,

Parul Institute of Engineering and Technology, Waghodia, Vadodara.

E-mail ID: [email protected]

Abstract:The environment is being polluted by humans & in doing so,

not only air & water but land is also being contaminated. The

major contaminant of soil is oil. These contaminations largely

affect the geotechnical properties of soil, specially physical &

chemical. Taking into consideration the structural safety of

structures of such location it is necessary to consider the

change in the geotechnical properties due to such

contaminations. In this paper the changes in the geotechnical

properties like plastic limit, liquid limit, specific gravity,optimum moisture content, maximum dry density, cohesion,

angle of internal friction, and California bearing ratio of

black cotton soil with 5%, 10% and 15% castor oil as

contaminant is represented. After that the effect of sawdust as

stabilizer on black cotton soil contaminated with 10% castor

oil is observed.

Keywords: plastic limit, liquid limit, specific Gravity,

optimum moisture content, maximum dry density, cohesion,

angle of internal friction, California bearing ratio, castor oil,

contamination, sawdust, stabilize

1. Introduction

Rapid increase in the population all over the world is directlyproportional to the development programmers in housing and

construction for industrial enhancement. Nowadays it can be

shown that geotechnical work and earning are directly related

to the industrialization that in turn brings pollution effect to

the surrounding. The rapid growth of industrialization has

created several problems in all parts of the world. In the

present situation, if industrial development for the benefit of

humanity is not properly planned then environment is being

adversely affected at a great speed. Increasing of

industrialization and changes in land use pattern have resulted

in general degradation of the soil i.e. pollution of soil, water

and air which affect the technology of the environment area

and vice versa.

Oil contaminated soil is defined as any earthen material or

artificial fill that has human or natural alteration in its

physical, chemical, biological or radiological integrity

resulting from the introduction of crude oil, any fraction or

derivative there of (such as gasoline, diesel, or Motor oil) or

oil based product.

Oil contamination of soils may occur through a variety of

sources such as oil leakage from damaged pipelines, tanker

accidents, and discharge from coastal facilities or natural

seepage. One typical example is the oil spills in Kuwait during

the Gulf war. Another example is the oil spill at Valdez,

Alaska resulting from an oil tanker accident. In Saudi Arabia,

soil is being contaminated by the leakage of oil from damaged

pipelines and oil storage tanks. Despite the best efforts of

both, petroleum industry and regulatory community releases,

leakages and spills of petroleum products occurs frequently. Itis estimated that in the United States, 25% of the storage of

petroleum products are leaking. Once a spill or leakage occurs,

the hydrocarbon liquid under gravity moves down to thegroundwater partially and upon reaching the ground water

table, this liquid may spread horizontally by migration within

the capillary zone, thereby further saturating the soil. Clay

particles are chemically active soil particles. Their behavior is

always affected by the environment to variable degree

depending on the clay particles mineralogy. The particular

environment includes the pore fluids, their properties and type

of ions present therein. Their behavior can be altered

substantially by the presence or permeation of different pore

fluids. Nowadays castor oil is also used in industries like in

the manufacturing of soaps, plastics, synthetic resins, fibers,paints, varnishes, lubricants, dyes, leather treatments, grease,

hydraulic fluids, machining oils, rubbers and as bio fuel. Due

to these all uses, it may contaminate soil. Due to soil

contamination by various liquids from different sources, clay

behavior may change.

Most foundation design and construction is based on ASTM or

Indian standards, in which distilled water is a standard control

pore fluid at room temperature. Since many underground

soil/water systems are polluted to some degree, some

difference in soil properties exists in laboratory and in site

conditions. Therefore certain analysis and design procedures

for foundation structures must be revised or modified. Most

foundation structures require friction or adhesive force

between structure and soil for earth pressure, pile capacity andbearing capacity compaction. Unfortunately this force changes

frequently if the groundwater table fluctuates.

The present study shows the interaction behavior of typical

CH type black cotton soil and castor oil. To study the

interaction effects, the soil has been tested with varying

percentage of oil. The physical and engineering properties of

virgin soils and contaminated soils were determined.

13-14 May 2011 B.V.M. Engineering College, V.V.Nagar,Gujarat,India

National Conference on Recent Trends in Engineering & Technology


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2. Materials & Methods

2.1 Materials:

The experimental work was conducted with Black cotton soil,

procured from Karajan, Gujarat. Castor oil was used as

contaminant and sawdust as stabilizer. The soil was

contaminated in the laboratory with varying percentage of

castor oil as contaminant to study the contaminants effect on

various geotechnical properties of soils.

2.2 Procedure of Contamination:

Initially, the soil is air dried and hand sorted to remove the

pebbles and vegetable matter, if any. It is then oven dried,

ground, pulverized and sieved through a 425 sieve. The soilis then contaminated by castor oil in varying percentage i.e.

5%, 10% and 15% by weights and tested to determine their

physical and engineering properties. After that black cotton

soil contaminated with 10% castor oil is stabilized with

sawdust. The sawdust is mixed with contaminated soil invarying percentages, i.e. 2.5%, 5%, 7.5% &10% by weights.

The aim of the investigation is to examine the effect of

contaminant and stabilizer on various geotechnical properties

of soil. Following laboratory tests have been performed to

study the geotechnical properties of soil before and after

contamination.

Physical and Engineering properties

- Atterbergs Limits

- Maximum Dry density and optimum moisture

content

- Specific gravity

- Strength test

- CBR test

2.3 Experimental Work

The experimental schedule for collecting data is shown in the

following tables.

Table 1: Test performed on Black cotton Soil

Contaminated soilTest Black

cotton Soil

C5 C10 C15Atterberg Limit

M.D.D

O.M.C

Specific gravity U.C.S

Triaxial Test

C.B.R test

C=Castor Oil, Suffix is percentage of contamination

Table 2: work schedule for finding out effect of sawdust as

stabilizer on Black cotton soil contaminated with 10%

castor oil

Contaminated soil for stabilization (saw Dust)

2.5% 5% 7.5% 10%No. of Days No. of Days No. of Days No. of Days

Test

1 3 7 14 1 3 7 14 1 3 7 14 1 3 7 14UCS Tria

xial

CBR

Here, No. of Days is days after mixing sawdust with

contaminated soil

3. Result & Discussion

3.1 Result:

The effect of castor oil contamination on geotechnical

properties of black cotton soil is shown in table 3 & effect of

stabilizer on geotechnical properties of black cotton soil

contaminated with 10% castor oil is shown in table 4.

Table 3: Various Geotechnical Properties of virgin black

cotton soil and contaminated black cotton soil

Contaminated black cotton

soilProperties of soil

Virgin

Black

cotton

soilC5 C10 C15

Specific Gravity 2.58 2.14 1.99 1.97Liquid Limit(%) 77.14 72.43 69.28 56.49

Plastic Limit (%) 38.55 37.99 36.22 33

Maximum Dry

Density(gm/cc)1.59 1.55 1.52 1.68

Optimum Moisturecontent (%)

20.5 16.91 14.36 7.19

Unconfined

Compressive Strength(kg/cm2)

1.19 0.62 0.61 0.36

Cohesion (kg/cm2) 1.42 0.84 0.6 0.46

Angle of internalfriction (Deg.)

3.08 11.18 11.49 12.95

CBR (Unsoaked) 17.83 21.34 20.77 18.53

CBR (soaked) 3.09 1.12 1.03 1.68




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Table 4: Effect of saw dust on engineering properties of

black cotton soil contaminated with 10% castor oil

Percentage of saw dust

Properties of

soil

No. of

day for

aging

period

Cont

amin

ated

soil

2.5%

5% 7.5%

10%

1 0.61 1.02 1.83 3.07 2.58

3 0.61 1.03 2.43 3.12 2.92

7 0.61 1.39 2.49 3.45 3.29

Unconfined

CompressiveStrength

(kg/cm2) 14 0.61 1.73 3.03 4.17 3.96

Cohesion

(kg/cm2)14 0.6 0.52 1.2 0.53 0.14

Angle of internalfriction (Degree)

14 12.9 25.8 16.1 25.9 34.6

CBR Value

(Unsoaked)1 20.77 15.3 10.1 17.1 24.7

CBR Value

(soaked)1 1.03 1.4 0.37 1.26 1.12

0.61 0.61 0.61 0.61

1.02 1.03

1.39

1.731.83

2.432.49

3.033.073.12

3.45

4.17

2.58

2.92

3.29

3.96

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

1 3 7 14

Aging period of stabilization (days)

Unconfinedcompr

essivestrength(kg/cm2)

Black cotton soilcontaminated with 10%

castor oil

Black cotton soilcontaminated with 10%

castor oil +2.5% sawdust

Black cotton soil

contaminated with 10%

castor oil +5% sawdust

Black cotton soil

contaminated with 10%

castor oil +7.5% sawdust

Black cotton soil

contaminated with 10%castor oil +10% sawdust

Fig. 1 Effect of Sawdust on unconfined compressive strength

of black cotton soil contaminated with 10% custor Oil

Fig. 2 Effect of Sawdust on Cohesion and angle of internal

friiction of Black cotton soil contaminated with 10% custor oil

Fig. 3 Effect of Sawdust on CBR value (Soaked and

Unsoaked) of Black cotton soil contaminated with 10% custor

oil

3.2 Discussion:

The specific gravity, Liquid limit, plastic limit and optimummoisture content of black cotton soil were observed to be

decreasing with increase in percentage of contaminant. Forblack cotton soil contaminated with 5% and 10% castor oil,

the maximum dry density was found less than that of virgin

soil and for 15% contaminant, it was found more than that of

virgin soil. The unconfined compressive strength and cohesion

of contaminated black cotton soil decrease as percentage of

contaminant increases while angle of internal friction was

20.77

1.03

15.3

1.4

10.1

0.37

17.1

1.26

24.7

1.12

0

5

10

15

20

25

30

CBR Value (Unsoaked) CBR Value (soaked)

Aging Period of stabilitation (1day)

Values

Black cotton soil contaminated with

10% castor oil


10% castor oil +2.5% sawdust


10% castor oil +5% sawdust





0.6

12.9

0.52

25.8

1.2

16.1

0.53

25.9

0.14

34.6

0

5

10

15

20

25

30

35

40

Cohesion (kg/cm2) Angle of internal friction

(Degree)

Aging period of stabilization (14days)

values


10% castor oil












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observed to be increasing as percentage of contaminant

increased. The CBR value (soaked & unsoaked) was seen to

be decreasing as percentage of contaminant increased but

unsoaked CBR values are found greater than that of virgin

soil.

The Unconfined compressive strength (UCS) of stabilized

black cotton soil contaminated with 10% castor oil increased

by 67.21% at 1st

day, 68.85% at 3rd

day, 128.4% at 7th

day and

183.31% at 14th

day with 2.5% stabilizer. It increased by

199.36% at 1st

day, 298.57% at 3rd

day, 308.5% at 7th

day and

396.38% at 14th

day with 5% stabilizer. It (UCS) found to

increase by 403.41% at 1st

day 411.47% at 3rd

day, 465.57% at

7th

day and 583.6% at 14th

day with 7.5% stabilizer. It (UCS)

increased by 322.76% at 1st day, 378.68% at 3rd day, 440.08%

at 7th

day and 549.18% at 14th

day with 10% stabilizer.

The cohesion of stabilized black cotton soil contaminated with

10%castor oil found to decreased by 13.10% with 2.5%

stabilizer, increased by 99.83% with 5% stabilizer, decreased

by 12.93% and 77.44% with 7.5% and10% stabilizerrespectively. The angle of internal friction of stabilized soilincreased by 99.38%, 24.63%, 100.38% and 167.87% with

2.5%, 5%, 7.5%, and 10% stabilizer respectively.

The CBR value (unsoaked) of stabilized soil decreased by

51.33%, 26.06%, 17.29% and 18.9% with 2.5%, 5%, 7.5%

and 10% stabilizer respectively.

The CBR value (soaked) of stabilized soil decreased by

64.05% with 2.5% stabilizer, while increased by 8.8%,

22.72% and 36% with 5%, 7.5% and 10% stabilizer

respectively.

4. Conclusion

4.1Effect of contaminant:The geotechnical properties of black cotton soil found to be

greatly affected by 15% castor oil among the various

percentage of contaminant.

4.2 Effect of stabilizer (sawdust) on contaminated soil:The unconfined compressive strength of stabilized soil

increases as the time duration increases. The maximum

unconfined compressive strength found on the 14th

day with

7.5% sawdust. The angle of internal friction was found in an

irregular pattern. The cohesion was found maximum with 5%

sawdust and minimum with 10% sawdust. The maximum

unsoaked CBR value of stabilized soils found with 10%

sawdust, while minimum with 5%. The maximum soaked

CBR value of stabilized soils found with 2.5% sawdust, whileminimum with 5% sawdust.

References:

A. Fotinich, V.K.Dhir, and S. Lingineni (January-

1999)Remediation of simulated soils contaminated with

Diesel, Journal of Enviornmental engineering, p.g 36-45

Hasan A. Al-sanad,Walid K-Eid and Nabil F-Ismael (may-

1995) Geotechnical Properties of Oil Contaminated Kuwaiti

Sand ASCE Journal of Geotechnical Engineering p.g.407-

415

Hasan A. Al-sanad and Nabil F-Ismael (march-1997 AginingEffect on Oil Contaminated Kuwaiti Sand ASCE Journal of

Geotechnical and Geoenvironmental Engineering p.g.290-293

Jay N.Meegoda (January 1999) Stabilization / Solidification

of Petroleum contaminated Soils with Asphalt Emulsions

Practice Periodical of Hazardous, Toxin, and Radioactive

Waste Management p.g.46-55

Sanjay J shah, A.V.Shroff, Jignesh V Patel, K.C. Tiwari, D

Ramakrishanan (2003) stabilization of Fuel Oil

Contaminated Soil-A Case Study Geotechnical and

Geological Engineering, p.g.415-427

P Tiwari, M.K. Gupta and R.K Srivastava (2006) Laboratory

Studies on Surfactant Enhanced Remediation of Engine OilContaminated Soils, Indian Geotechnical Journal 36(4), p.g.287-298



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