SOIL STABILISATION BY USING FLY ASH

A report submitted in partial fulfilment of the requirementsFor the degree of

BACHELOR OF TECHNOLGY IN CIVIL ENGINEERING

by Gyan dev (1201037)

Abhishek Kumar (1201029)

Saurabh Yadav(1201035) Supervisor Asst. prof. - alka tiwari

SCHOOL OF CIVIL ENGINEERINGKIIT UNIVERSITY

751024NOVEMBER 2015

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ACKNOWLEDGEMENT

It is with immense pleasure that I express my sincere sense of gratitude and humble

appreciation to Asst prof. Alka Tiwari for his invaluable guidance, whole-hearted co-

operation, constructive criticism and continuous encouragement in the preparation of

this thesis. Without his support and guidance, the present work would have remained

a dream.

I would also like to thank Prof. BG Mohapatra Dean, School of Civil

Engineering KIIT UNIVERSITY, for providing necessary facilities.

I take this opportunity to thank all my scholar friends & family for their

valuable support and encouragement throughout the preparation of this work. I also

thank all those who have directly or indirectly helped in completion of this work.

November 2015, Gyan Dev (1201037) kiit university Saurabh yadav (1201035) Abhishek kumar (1201029)

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DECLARATION OF SCHOLAR

We hereby certify that the work which is being presented in the report entitle "soil

stabilization using Fly Ash" in partial fulfilment of the requirements for the award of

the degree of Bachelor of Technology in School of Civil Engineering under KIIT

University, Bhubaneswar is an authentic record of my own work carried out during

the period from 2015 to 2016 under the supervision of Asst. prof. Alka Tiwari.

The matter present in this thesis has not been submitted by us for the award of any

other degree of this or any other University/Institute.

Gyan dev(1201037)

Saurabh Yadav(1201035)

Abhishek Kumar(1201029)

This is to certify that above statement made by the student is correct to the best of our

knowledge.

Asst. prof. Alka Tiwari

(Supervisor)

School of Civil Engineering

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CONTENT

TOPICS PAGE NOS.

1 ABSTRACT 6

2 INTRODUCTION 7-8

3 SOIL USED FOR CONSTRUCTION 9

4 LITERATURE REVIEW 10-12

5 FORMATION OF FLY ASH 13

6 TYPES OF FLY ASH 14

7 MIXING OF FLY ASH 15

8 COMPACTION 16-17

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9 USE OF FLY ASH 18

10 CONCLUSION 19

11 REFERENCES 20

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ABSTRACT

Soil stabilization is one of most important for the construction which is widely used in connection with road pavement and foundation construction because it improves the engineering properties of soil such as strength, volume stability and durability. In the present investigation is to evaluate the compaction and unconfined compressive strength of stabilized black cotton soil using fine and coarse fly ash mixtures. The percentage of fine and coarse fly ash mixtures which is used in black cotton soil varied from 5 to 30. In the study concludes that with percentage addition of fine, coarse fly ash improves the strength of stabilized black cotton soil and exhibit relatively well-defined moisture-density relationship. It was found that the peak strength attained by fine fly ash mixture was 25% more when compared to coarse fly ash.

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1. INTRODUCTION

1.1 GENERAL

Stabilization of soil is improvement of soil's properties. It also increases the soil shear strength and controls the shrinkage-swelling properties of a soil, thus increases the load bearing capacity.

Fly ash constitutes of very small particles and enters into the voids of soil when mixed with it thus increases grain to grain contact of soil particles due to which effective stress of soil increases and soil became more dense and compact thus increases its bearing capacity and soil became more stabilize.

Soil stabilization may be utilized on various projects such as roadways, parking areas, site development, airports, embankment etc. where soil alone is not good for construction, Methods of stabilization may be utilized to improve subgrade materialsRanging from clayey to granular soil materials. It is achieved by use of additives like, fly ash, and Portland cement, lime kiln dust and cement-kiln dust are also used for stabilization.

1.2 Advantage of soil stabilization process are

It gives increased resistance values Increases effective stress of soil Increases load bearing capacity of soil Decreases permeability of soil Reduces the thickness of pavement to be constructed

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There are many environmental advantages such as roadways are stabilized, stop erosion. Soil stabilization is useful in conserving soils, unimproved roadways and etc.

1.3 OBJECTIVE OF THE REPORT

Study of soil used for construction.

To study literature review for detail understanding of soil stabilization using fly-ash addition.

Formation of fly ash.

Types of fly ash.

Methods of mixing of fly-ash with soil

To study the outcomes of fly ash on maximum dry density and optimum moisture content of clayey soil.

1.4 MOTIVATION

Intrest in geo-tech engineering.

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2. SOIL USED FOR CONSTRUCTION

Fig 1. Soil without fly ash reference-(net)

Infrastructure projects such as highways, railways, water reservoirs, reclamation etc. requires earth Material in very large quantity. In urban areas, borrow earth is not easily available which has to be Hauled from a long distance. Quite often, large areas are covered with highly plastic and expansive Soil, which is not suitable for such purpose. Extensive laboratory / field trials have been carried out by various researchers and have shown promising results for application of such expansive soil after Stabilization with additives such as FLY ASH, etc.

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3. LITERATURE REVIEW

Fly Ash by itself has little cementatious value but in the presence of moisture it reacts chemically and forms cementatious compounds and attributes to the improvement of strength and compressibility characteristics of soils. It has a long history of use as an engineering material and has been successfully employed in geotechnical applications.

Erdal Cokca (2001)Cokca studied the effect on fly ash on expansive soil. He used Soma fly ash and Tuncbilek fly ash with at 0-25% range and cured for 7 through 28 days and tested by oedometer free swell test. Plasticity index, swelling potential and activity of soil increased with increase in the stabilizer. The swelling potential was 20%. It was recommended that high calcium, low calcium Class C fly ash may be used as stabilizing agents.

Sharma (2001)Studied mixing of fly ash and lime on clayey soil. It was found out that 20% fly ash optimum considering the UCS of the soil. For soil sample, using fly ash was not adequate enough and hence lime was used as a stabilizing agent in addition. The CBR moved up by 5.7% by addition of 20% of fly ash & 8.5% of lime.

Pandian (2002)Carried out experiments on black- cotton soil using different fly-ashes percentages increasing from 0-100%. Because of more content of clay fraction, the strength and hence the CBR of the black soil is low, which increases to by 60% due to fly ash. Also, Neyvalli fly ash provided additional strength to the soil due to reactions.

Nikolas Hansson (2002)Studied the use of fly ash deep soil stabilization. Different percentages of cement, lime and fly ash were mixed with clay soil and specimens were allowed to cure for 7, 28 and 56 days. Unconfined and triaxle compression test results showed that hard coal ash ash gave the best result.

S.Kolias (2004)Carried out work on the changes due addition of high calcium fly-ash and cement on finely grained soils. Strength test were conducted in uniaxial compression indirect

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splitting and flexure. Modulus of elasticity and soaked CBR values at 90 days. He compared pavements with subgrades having fly ash and cement with flexible pavements without modified subgrades and found it to be better in terms of strength bearing. The benefits of this stabilization is that it depends on type of soil, stabilizing agent. Product formed during curing of clay containing fly ash and cement gave a more stable and denser structure.

Sharma and Panikumar (2004)Studied the changes in properties by addition of fly ash to expansive soil. The swelling index, swelling potential, swelling pressure, plasticity index, compaction, strength and hydraulic conductivity of soil was studied by adding fly ash at 5%,10%,15% and 20%.

Zumrawi and Hamza (2007)Studied the swelling and strength nature of soils stabilized with lime, fly ash and a combination of both at ranges 0-40%. Index properties, CBR, UCS, free swell and swell pressure tests were conducted. The CBR and UCS of the soil sample increased.

Al-Dahlaki(2007)Studied the influence of fly ash at different percentages on engineering properties for heavy soils. The percentages of fly ash varied from 0-25% and a curing time was set for 0, 10, 30 days. The swelling reduction also increased with increasing fly ash content.

Saravanan (2013)Studied fly ash to clayey soil collected from Tiruchengode, Tamil Nadu at 0-40%. The Atterberg limits, specific gravity, unconfined compressive strength and standard proctor compaction tests were done. The tests revealed that on mixing fly specific gravity and plasticity index reduced and increased the MDD and OMC of the soil. The optimum content of fly ash was 10%.

Satayanarayana and Naidu (2014)Studied the behaviour of soils by adding fly ash with sodium silicate and lime at different percentages and analysed their strength at their free pouring (30%, 35% and 40% of water by weight of fly ash). Results were taken for UCS and split tensile tests at different curing periods at 3,7,28 days. It was found out that 10-15% lime and 3-5% of sodium silicate.

Ahmed (2014)Studied the stabilization of clayey soil for durable urban road construction. The plasticity index reduced by 30% and liquid limit reduced limit to 54.12% and bearing capacity with increased with increased with increased fly ash content. Also the CBR of the soil increased from 3-56%. It was found that optimum fly ash content was 15% by weight.

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Ravichandran (2015)Studied the properties of soil with addition of Photophogypsum and fly ash. This attempt was made to reduce the swell potential of soil. After adding the stabilizer, the strength of the soil showed a improvement. The photophogypsum-fly ash stabilized clay by occupying the voids and undergoing reactions.

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4. FORMATION OF FLY ASH

Fig 2 fly ash (reff.-net)

Fly ash is a by-product from burning pulverized coal in electric power generating plants. During combustion, mineral impurities in the coal (clay, feldspar, quartz, and shale) fuse in suspension and float out of the combustion chamber with the exhaust gases. As the fused material rises, it cools and solidifies into spherical glassy particles called fly ash. Fly ash is collected from the exhaust gases by electrostatic precipitators or bag filters.

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5. TYPES OF FLY ASH

5.1 CLASS F FLY ASH

The burning of harder, older and bituminous coal typically produces Class F fly ash. This fly ash is pozzolanic in nature, and contains less than 20% lime.

5.2 CLASS C FLY ASH

Fly ash produced from the burning of younger lignite or sub-bituminous coal, in addition to having pozzolanic properties, also has some self-cementing properties. In the presence of water, Class C fly ash hardens and gets stronger over time. Class C fly ash generally contains more than 20% lime (cao)

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6. MIXING OF FLY ASH WITH SOIL

Fig 3 harrow mixture (reff.- net)

Fly ash can be mixed manually by hand or by using some tools for small work such as in lab for practical purpose.

Machine such as disc harrow can be used for large construction work such as road construction, embankment etc.

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7. COMPACTION OF SOIL FLY ASH MIXTURES

• The compacted unit weight of the material depends on the amount and method of energy application, grain size distribution, plasticity characteristics and moisture content at compaction.

• The tendency for fly ash to be less sensitive to variation in moisture content than for soil is due to higher air void content of fly ash

• The higher void content could tend to limit the build-up of pores pressures during compaction, thus allowing the fly ash to be compacted over a larger range of water content.

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7.2 COMPACTION TEST RESULT

As we see that with the increase in amount of fly ash with soil, maximum dry density increases at same water content thus increases the physical properties of soil such as its bearing capacity, effective stress, denseness etc.So presence of fly ash increase the physical as well as chemical properties of soil.

Maximum of 30% fly ash of total soil is added.

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Source: ISSN: 2319-5967 ISO 9001:2008 (certified)

8. USES OF FLY ASH

8.1 ROAD COSTRUCTION

Fly ash increases the bearing capacity of soil due to which pavement thickness is can be reduced.

Fig 4 A road roller flattening the fly ash (reff.-net)

8.3 EARTHEN DAMS

When fly ash is mixed with earth then the voids of soil gets filled by it thus soil became denser and its permeability decreases so seepage through earthen dams reduces to large extent due to addition of fly ash.

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Fig 5 Earthen dam (reff.-net)

CONCLUSION

An attempt has been undertaken to make the soil suitable for engineering construction. Industrial waste material such as Fly Ash is considered to be one of the improvement materials due to cohesion less in nature. Various percentage of Fly Ash (10, 20, and 30%) has been added to the natural soil. The test results corresponding to 30% addition has shown encouraging parameters. It is also considered to be appropriate from the project point of view that 40% addition could be done on site to make the existing soil suitable.

Hence it is recommended that, the soil may be utilized with modification in Civil Engineering project such as road construction, filling below foundation etc.

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REFRENCES

1) Usman MA, Bowders Jr JJ. “stabilization characteristics of class F fly ash”. Volume 13. Number 2.November 2012(fall).

2) Erdal Cokca “Use of Class C Fly Ashes for the stabilization- of an Expansive soil”, A journal of Geotechnical Engineering, Volume 127, July 2001

3) Idon J. Yoder, “Principles of soil stabilization”, JHRP Publication Indiana. Volume 13.Number 2. November 2012

4) Chen, F.H, “Foundations on expansive soils”, C &A, Elsevier Publications, Volume 10, Issue 6, Jan. 2014.

5) Gopal Ranjan, A.J.R Rao, a textbook on “Fundamentals of soil mechanics”.

6) Srivastava Amit. ,Pandey Shikha. , and RanaJeeshant. “Use of shredded tyre waste in improveing yhe geotechnical properties of expansive black cotton soil”. Volume 9, issue 4, 2014

7) Phani Kumar SR, Sharma RS (2004) “Effect of fly ash on engineering properties of expansive soils”. Volume 3, issue 11, November 2013

8) F.G.Bell, “Engineering treatment of soils,” section 4, vol. 04.02, 04.08 and 04.09, Conshohocken

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10) Jones, D.E., and jones, k.a., Treating Expansive soils”, Civil engineering, ASCE, August, 1987.

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