Project Report on Soil Stabilization Using Lime and Fly Ash

ABSTRACT ABSTRACT

Soil is the basic foundation for any civil engineering structures.It is required to Soil is the basic foundation for any civil engineering structures.It is required to  bear the loads without fai

 bear the loads without failure.In some places, soil may be weak whlure.In some places, soil may be weak which cannot resistich cannot resist the oncoming loads.In such cases,soil stabilization is needeed.Numerous methods the oncoming loads.In such cases,soil stabilization is needeed.Numerous methods are

are avaavailailable ble in in the the litliteraeraturture e for for soisoil l stastabilbilizaizatiotion.Bn.But ut somsometietimesmes,so,some me of of thethe metho

methods ds like like chemichemical cal stabistabilizatlization,lion,lime ime stabstabilizailization tion etc. etc. adveradversly sly affaffects ects thethe chemical composition of the soil.

chemical composition of the soil.

In this study,fly ash and lime were mied with clay soil to investigate the relative In this study,fly ash and lime were mied with clay soil to investigate the relative st

strerengngth th gagain in in in tetermrms s of of ununcoconfnfinined ed cocompmpreressssioion,n,bebeararining g cacapapacicity ty anandd compaction.!he effect of fly ash and lime on the geotechnical characteristics of  compaction.!he effect of fly ash and lime on the geotechnical characteristics of  cla

clay"fy"fly ly ash ash and and claclay"ly"lime ime mimiturtures es was was invinvestestigaigated ted by by conconducductiutiung ng stastandandardrd #roctor compaction tests,unconfined compression tests,$B% tests and permeability #roctor compaction tests,unconfined compression tests,$B% tests and permeability test.!he tests were performed as per

test.!he tests were performed as per Indian Standard specifications.Indian Standard specifications. !he following materials were used for preparing the samples&

!he following materials were used for preparing the samples&



 $layey soil$layey soil



 'ly ash'ly ash



 (ime(ime !he

!he sofsoft t claclay y useused d for for thethese se epeperierimenments ts was was brobroughught t from from a a sitsite,ne,near ear  )u

)umamararakokom.m.!h!he e phphysysicical al prpropopertertieies s of of ththe e sosoil il wewere re dedetetermrminined ed as as peper r ISIS specifications.

specifications. 'ly ash for the

'ly ash for the study was brought study was brought from *industan Newfrom *industan Newsprints,#iravam.it is sprints,#iravam.it is finelyfinely divi

divided residue resultinded residue resulting g from the from the combucombustion of stion of grounground d or powdered coal or powdered coal fromfrom electric generating plants. It has

electric generating plants. It has high water absorption capacity.high water absorption capacity.

(ime for the study is locally available.it imparts much strength to the soil by (ime for the study is locally available.it imparts much strength to the soil by  pozzolanic reaction w

In this test programme,without additives clay was tested to find the optimum In this test programme,without additives clay was tested to find the optimum mo

moisistuture re cocontntenent t ,$,$B% B% vavalulue e ,p,plalaststicicitity y inindede  anand d ununcoconfnfinined ed cocompmpreressissionon stren

strength.'gth.'ly ash ly ash and lime and lime were added in were added in varyinvarying g percenpercentages and tages and that fractiothat fraction n for for  which maimum strength is obtained was found out.!he miture is cured for +, which maimum strength is obtained was found out.!he miture is cured for +, and - days. and - days. CHAPTER 1 CHAPTER 1 INTRODUCTION INTRODUCTION

General General

!ransport in the %epublic of India is an important part of the nation/s

!ransport in the %epublic of India is an important part of the nation/s economyeconomy.. %oads are the vital lifelines of the economy making possible trade and commerce. %oads are the vital lifelines of the economy making possible trade and commerce. !hey are the most preferred modes of transportation and considered as one of the !hey are the most preferred modes of transportation and considered as one of the cost effective modes. 0n efficient and well"established network of roads is desired cost effective modes. 0n efficient and well"established network of roads is desired for promoting trade and commerce in any country and also fulfills the needs of a for promoting trade and commerce in any country and also fulfills the needs of a sou

sound nd tratranspnsportortatiation on syssystem tem for for sussustaitained ned ecoeconomnomic ic devdeveloelopmepment. nt. !!o o proprovidvidee mobility and accessibility, all weather roads should connect every nook and corner  mobility and accessibility, all weather roads should connect every nook and corner  of the country. !o sustain both static and dynamic load, the pavement should be of the country. !o sustain both static and dynamic load, the pavement should be designed and constructed with utmost care. !he performance of the pavement designed and constructed with utmost care. !he performance of the pavement depends on the quality of materials used in

depends on the quality of materials used in road constructionroad construction..

Sub grade is the in situ

Sub grade is the in situ material upon which the pavement structure is placed.material upon which the pavement structure is placed. 0l

0lththouough gh ththere ere is is a a tetendndenency cy to to lolook ok at at papavevemement nt peperforformrmanance ce in in teterms rms of of   pavement

 pavement structures structures and and mi mi design design alone, alone, the the subgrade subgrade soils soils can can often often be be thethe overriding factor in pavement performance. !he construction cost of

overriding factor in pavement performance. !he construction cost of the pavementsthe pavements will be considerably decreased if locally available low cost materials are used for  will be considerably decreased if locally available low cost materials are used for  construction of lower layer of pavements such as subgrade, sub base etc.If the construction of lower layer of pavements such as subgrade, sub base etc.If the stability of local soils is not adequate for supporting the loads, suitable methods to stability of local soils is not adequate for supporting the loads, suitable methods to enhance the properties of soil need to be adopted. Soil stabilization is one such enhance the properties of soil need to be adopted. Soil stabilization is one such method. Stabilizing the subgrade with an appropriate chemical stabilizer 1such as method. Stabilizing the subgrade with an appropriate chemical stabilizer 1such as

2uicklime, #ortland cement, 'ly 0sh or$omposites3 increases subgrade stiffness 2uicklime, #ortland cement, 'ly 0sh or$omposites3 increases subgrade stiffness and reduces epansion tendencies, it performs as a foundation 1able to support and and reduces epansion tendencies, it performs as a foundation 1able to support and

distribute loads under saturated conditions3. !his report contains a summary of the  performance of lime and fly ash used with clay.

'ly ashes are finely divided residue resulting from the combustion of ground or   powdered coal from electric generating plants.

(ime is another additive used, which is locally available, to improve subgrade characteristics. It is obtained by heating limestone at elevated temperatures.

SCOPE OF THE PROJECT

!he soil used in the study is natural clay brought from )umarakom.#avement subgrade over there is composed of clayey soil whose bearing capacity is etremely low.4ue to this reason ,the roads require periodic maintenance to take up repeated application of wheel loads.!his proves to be costly ,and at the same time, conditions of raods during monsoon seasons is etremely poor.!herefore, a thought on how to enhance the stability of roads by chaper means demands appraisal.

Soil stabilization can be done using different additives ,but use of fly ash which is a waste material from thermal power plants,at the same time difficult"to"dispose material will be much significant.

OBJECTIVES OF THE PROJECT !he ma5or ob5ectives of the pro5ect are&

-. !o eplore the possibility of using flyash in road construction programme. 6. !o study the effect of lime and flyash on proctor7s density and 89$ of 

clayey soil.

+. !o study the effect of lime and flyash on the consistency limits of clayey soil.

. !o study the changes in $B% of soil by the addition of lime and fly ash :. !o study the effect of curing period on the properties of clayey soil.

CHAPTER 2

LITERATURE REVIEW General

Stabilization is the process ofblending and miing materials with a soil to

improve certain properties of the soil. !he process may include the blending of  soils to achieve adesired gradation or the miing of commerciallyavailable additives that may alter the gradation, teture or plasticity, or act as a binder for  cementationof the soil.

!he process of reducing plasticity and improving the teture of a soil is called soil modification. 9onovalent cations such as sodium and potassium are commonly found in epansive clay soil and these cations can be echanged with cations of  higher valenciessuch as calcium which are found in lime and flyash. !his ion echange process takes place almost rapidly, within a few hours. !he calcium cations replace the sodium cations around the clay particles, decreasing the size of   bound water layer, and enable the clay particle to flocculate. !he flocculation

creates a reduction in plasticity, an increase in shear strength of clayey soil and improvement in teture from a cohesive material to a more granular, sand"like soil. !he change in the structure causes a decrease in the moisture sensitivity and increase the workability and constructability of soil. Soil stabilization includes the effects from modification with a significant additional strength.

Soil sr!"!re

!he clay particles in the soil structure are arranged in sheet like structures composed of silica tetrahedral and alumina octahedra. !he sheets form many different combinations, but there are three main types of formations .the first is kaolinite,which consists of alternating silica and alumina sheets bonded together. !his form of clay structure is very stable and does not swell appreciably when wetted .the net form is montmorillonite, which is composed of two layers of silica and one alumina sheet creating aweak bond between the layers. !his weak bonding

 between the layers allows water and other cations to enter between the layers,resulting in swelling in the clay particle. !he last type is illite, which is very similar to montmorillonite ,but has potassium ions between each layer which help  bond the layers together. Inter layer bonding illite is therefore stronger than for 

montmorillonite,but weaker than kaolinite.

$lay particles are small in size but have alarge to mass ratio,resulting in alarger  surface area available for interaction with water and cations.the clay particles have negatively charged surfaces that attract cations and polar molecules,including water forming a boundwater layer around the negatively charged clay particles. !he amount of water surrounding the clay particles is related to the amount of  water that is available for the clay particle to take in and release. !his moisture change around the clay particles causes epansion and swelling pressures within clays that are confined .

Uses o# sa$ili%aion

#avement design isbased on the premise that minimum specifiedstructural quality will be achieved for each layerof material in the pavement system. ;ach layermust resist shearing, avoid ecessive deflectionsthat cause fatigue cracking within the layer or inoverlying layers, and prevent ecessive permanentdeformation through densification. 0s the qualityof a soil layer is increased, the ability of that layerto distribute the load over a greater area isgenerally increased so that a reduction in therequired thickness of the soil and surface layersmay be permitted.

Quality improvement 

.

!he most common improvementsachieved through stabilization includebetter soil gradation, reduction of plasticity indeor swelling potential, and increases in durabilityand strength. In wet weather, stabilizationmay also be used to provide a working platformfor construction operations. !hese types of soilquality improvement are referred to as soil modification.

Thickness reduction.

!he strength and stiffnessof a soil layer can be improved through theuse of  additives to permit a reduction in designthickness of the stabilized material compared withan unstabilized or unbound material.

STABILI&ATION TECHNI'UES

Sa$ii%aion (i) *orlan+ "e,en

#ortland cement can be used either to modify or improve the quality of the soil into a cemented mass with increased strength and durability. !he amount of cement used will depend upon whether the soil is to be modified or stabilized.

$ement stabilization is most commonly used for stabilizing silt, sandy soils with small quantities of silt or clayey fractions stabilization of soil with cement has been

etensively used in road construction. 9iing the pulverized soil and compact the mi to attain a strong material does this stabilization. !he material thus obtained by miing soil and cement is known as <soil cement7. !he soil content becomes a hard and durable structural material as the cement hydrates and develops strength. !he cementing action is believed to be the result of chemical reaction of cement with the siliceous soil during hydration.

Sa$ili%aion (i) $i!,en

Stabilization of soils and aggregates with asphalt differs greatly from cementand lime stabilization. !he basic mechanism involved in asphalt stabilization of fine grained soils is a water proofing phenomenon. Soil particles soil agglomerates are coated with asphalt that prevents or slows the penetration of water, which could normally result in a decrease in soil strength. In addition, asphalt stabilization can improve durability characteristics by making the soil resistant to the detrimental effects of water such as volume. In non"cohesive material such as sand and gravel, crushed gravel, and crushed stone, two basic mechanisms are active& water   proofing and adhesion. !he asphalt coating on the cohesion less materials provides

a membrane, which prevents or hinders the penetration of water and thereby reduces the tendency of the material to lose strength in the presence of water. !he second mechanism has been identified as adhesion. !he aggregate particle adheres to the asphalt and the asphalt acts as a binder or cement. !he cementing effect thus increases the shear strength by increasing adhesion. $riteria for design of   bituminous stabilized soils and aggregates are based almost entirely on stability

and gradation requirements. 'reeze"thaw and wet durability test are not applicable for asphalt"stabilized mitures.

S$ili%aion (i) li,e-"e,en an+ li,e-$i!,en

!he advantages in using combination stabilizers are that one of the stabilizers in the combination compensates for the lack of effectiveness of the other in treating a  particular aspect or characteristics of a given soil. 'or instance in clay areas devoid of base material, lime have been used 5ointly with other stabilizers notably #ortland cement or asphalt, to provide acceptable base courses. Since #ortland cement or  asphalt cannot be mied successively with plastic clays, the lime is incorporated into the soil to make it friable, thereby permitting the cement or asphalt to be adequately mied. =hile such stabilization might be more costly than the conventional single stabilizer methods, it may still prove to be economical in areas where base aggregate costs are high. !wo combination stabilizers are considered in this section.

-. lime"cement 6. lime"asphalt

Li,e-"e,en

(ime can be used as an initial additive with #ortland cement or the primary stabilizer. !he main purpose of lime is to improve workability characteristics mainly by reducing the plasticity of soil. !he design approach is to add enough lime to improve workability and to reduce the plasticity inde to acceptable levels. !he design lime content is the minimum that achieves desired results.

(ime can be used as an initial additive with asphalt as the primary stabilizer. !he main purpose of lime is to improve workability characteristics and to act as an anti" stripping agent. In the latter capacity, the lime acts to neutralize acidic chemicals in the soil or aggregate, which tend to interfere with bonding of the asphalt. >enerally, about -"6 percent lime is all that is needed for this ob5ective.

Sa$ila%aion $. /eo-e0iles an+ #a$ri"s

Introducing geo"tetiles and fabrics that are made of synthetic materials, such as  polyethylene, polyester, and nylon, can stabilize the soil. !he geo"tetile sheets are manufactured in different thickness ranging from -? to +?? mils 1-mil@?.6:mm3. !he width of sheet can be upto -?m. !hese are available in rolls of length upto about A??m.

>eotetiles are permeable. !heir permeability is compared to that of fine sand to course sand and they are strong and durable.

STABILI&ATION WITH LIE

(ime stabilization is done by adding lime to soil. !his is useful f or the stabilization of clayey soil. =hen lime reacts with soil there is echange of cations in the adsorbed water layer and a decrease in the plasticity of the soil occurs. !he resultant material is more friable than the orginal clay, and is more suitable as subgrade.

(ime is produced by burning of limestone in kiln. !he quality of lime obtained depends on the parent material and the production process. 0nd there are basically : types of limes

-. *igh calcium, quick lime 1$a83

6. *ydrated high calcium lime $a18*36C

+. 4olomitic lime $a8D9g8C

. Normal, hydrated 4olomitic lime $a18*36D9g8C

:. #ressure, hydrated dolomitic lime$a18*36D9g86C

!he two primary types of lime used in construction today are quick lime1calcium oide3 and hydrated lime 1calcium hydroide3.*eating limestone at elevated temperatures produce quick lime and addition of water to quick lime produces hydrated lime.

;quation shows the reaction that occurs when limestone is heated to produce quick  lime with carbon dioide produced as by"product.

$a$8+Dheat $a8D$86

0ddition of water to quick lime produces hydrated lime along with heat as  byproduct&

$a8D*68 $a 18*36D*eat

'or stabilization with lime,soil conditions and mineralological properties have a significant effect on the long term strength gain.

e")anis,

'or soil stabilization with lime, soil conditions and mineralogical properties have a significant effect on the long"term strength gain. 0 pozzolanic reaction between silica and alumina in the clay particles and calcium from the lime can form a

cemented structure that increases the strength of the stabilized soil. %esidual calcium must remain in the system to combine with the available silica or alumina to keep the p* high enough to maintain the pozzolanic reaction. Soil that should be considered for lime treatment include soils with a #I that eceeds -? and have more than 6: percent passing the E6?? sieve.

In lime stabilization the liquid limit of soil generally decreases but the plastic limit increases. !hus the plasticity inde of the soil decreases. !he strength of the lime stabilized soil is generally improved. It is partly due to the decrease in the plastic  properties of the soil and partly due to the formation of cementing material. Increase in the unconfined compressive strength is as high as A? times. !he modulus of elasticity of the soil also increases substantially.

0ddition of lime causes a high concentration of calcium ions in double layer. It causes a decrease in the tendency of attraction of water. $onsequently, the resistance of soil to water absorption, capillary rise and volume changes on wetting or drying is substantially increased. !he lime"stabilized bases or sub bases form a water resistant barrier which stops penetration of rain water. !here is an increase in optimum water content and a reduction in maimum density. In swampy areas where the water content is above the optimum, application of lime to soilhelps in drying of soil.

$yclic freezing and thawing can causes a temporary loss of strength, but because of subsequent healing action, there is no loss of strength in long run.

$onstruction methods used in lime stabilization are similar to those used in cement stabilization. *owever , the following points are to be noted.

-. 0s the reaction in the case of lime is low,there is no maimum time limit  between the addition of lime to the soil and the completion of

compaction. *owever ,care should be taken to avoid carbonation of lime in the process.

6. (ime may be added in the form of slurry instead of dry powder.

+. 0 rest period of - to  days is generally required for spreading lime over heavy clay before final miing is done. !his facilitates proper miing of lime and soil.

. !he soil"lime is compacted to the required maimum dry density. 0fter compaction, the surface is kept moist for  days and then covered with a suitable wearing coat. Sometimes, the wearing coat is applied soon after the compaction to help hold the moisture.

STABILI&ATION WITH FLASH

$lass $ flyash is an industrial byproduct generated at coal fired electricity generating power plants that contains silica,alumina and calcium based minerals.Fpon eposure to water,these calcium compounds hydrate and produce cementitious products similar to the products formed during the hydration of  #ortland cement.!he rate of hydration for flyash is much more rapid than #ortland cement.It is therefore more desirable to mi and compact flyash as quickly as  practical.

!he hydration property depends on coal source, boiler design and the type of ash collection system.!he coal source governs the amount and type of organic matter  present in it. ;astern coal source contain small amount of calcium. !his class '

flyash does not ehibitself"cementing characteristics. =estern coals contain higher amount of calcium 1about 6?G"+:G3 and are classified as class $ flyash.

!he amount of calcium oide in flyash is lower than that of lime and much of it is combined with silicates and aluminates, so flyash has less effect on plasticity than lime.

Boiler design and operation depends on the rate at which the hydration occurs. 4uring combustion the inorganic matter is fused consequently rapid cooling of  fused particles occur. So the flyash particles are non crystalline in nature.

$ompaction time after miing is critical to achieve maimum density and strength. =hen compaction is delayed hydration products begin to bond with loose particles and disruption of these aggregation is required to densify the material. So a portion of compactive energy isutilized in overcoming cementation and maimum densities are reduced.

In fly ash the high loss on ignition is due to the presence of unburnt carbon. !he combined amount of silica alumina and iron oide 1H.AG3 indicate its suitability as a pozzolanicmaterial.fly ash is no"plastic in nature.its moisture condition does not predominantly affect the dry density. !he fly ash has high angle of internal friction.

!he grain size distribution of is shown if fig 6. 'ly ash is a fine grained material .about HAG of the sample passes through : micron sieve indicating that fly ash is essentially a silt size material.

CHAPTER 3

E4PERIENTAL PROGRAE IN!%84F$!I8N

In this chapter, a brief review of various eperiments conducted using clay and the same stabilized with lime and flyash are eplained.

90!;%I0(S FS;4 -. $layey soil

Soil is brought from a paddy field in kumarakom.Soil over thereis highly  plastic clay. !herefore the strength of pavement subgrade needs to be

ascertained to withstand the compressive loadunder traffic. #roperties of clay usedin the study&

Sl No& #roperties alues

- $B% value .+G

6 9a.dry density -:- kgJm+

+ 8ptimum moisture

content

6?G

 (iquid limit +AG

: #lastic limit 6AG

A #lasticity inde -? 0 0.01 0.1 0 20 40 60 80 100 120

Particle size distribution for clayey soil

6.0dditives

!headditives used for stabilization and modification include lime and flyash. !he soils weremied with each of these additives for which there were

reasonable epectations of improved engineering properties. !he amount of  additive used was determined based on testing the strength for addition of  varying percentages and selecting the one with greatest strength. !he lime  percentage was fied at -?G and flyash -G.

#hysical properties and chemical composition of flyash

P).si"al *ro*eries

Specific gravity 6.6

(oss on ignition --.HG

C)e,i"al "o,*osiion

Silica 1Si863 :H.+G

0lumina 10l68+3DIron oide 1'e68+3 6A.+G

$alcium oide 1$a83 6.6G

9agnesium oide 19g83 ?.+G

LAB TESTING

!he various tests conducted on the sample are the following& -.0tterberg limits

6. Specific gravity +. 4irect shear test

. #roctor compaction test :. $B% test

'irstly the above tests were conducted on plane clay sample to determine its  properties.F$S test is conducted to evaluate it strength. !hereafter, certain

 percentages of lime and flyash are added to the clay sample to stabilize it. 0nd the  percentages of the above additives which produce the optimum strength to the soil

are chosen by conducting F$S test on them. Soil *re*araion

!he soil was collected from site in large sacks. It is brought to the lab and is dried in oven for 6 hours in large pans. !his soil due to loss of water formed big lumps which is broken to smaller pieces or even fine powder and is sieved according to the needs of different eperiments.

Co,*a"ion es

$ompaction is the densification of soil by reduction of air voids. !he purpose of a laboratory compaction test is to determine, the quantity of water to be added for field compaction of soil and resultant density epected. =hen water is added to dry fine grained soil, the soil absorbs water. 0ddition of more water helps in

sliding of particles over each other. !his assists the process of compaction. Fp to a certain point, additional water helps in reduction of air voids,but after a relatively high degree of saturation is reached, the water occupies the space ,which could be filled with soil particles, and the amount of entrapped air remains essentially

constant.!herfore,there is an optimum amount of water for a given soil and compaction process, which give rise to maimum dry density.

$ompaction of clay,clay"lime and clay"flyash mitures were carried out using standard proctor test with three layers on each 6: blows. Samples for  conducting compaction tests were prepared using moulds of dimensions -? cm diameter and -: cm height. In this study, lime is added for about -?G and cured for +, , and - days. 0lso,flyash is added for about -G and is cured for +, and

- days. !he values of optimum moisture content and maimum dry density are obtained in a plot of dry density versus moisture content.

Un"on#ine+ "o,*ression es

!his test is conducted on undisturbed or remoulded cohesive soils that are normally saturated.!his test may be considered as a special case of triaial compression test when the confining pressure is zero and the aial compressive stress only is applied to the cylindrical specimen. !he stress may be applied and the deformation and load readings are noted until the specimen fails. !he area of  cross section of specimen for various strains may be corrected assuming that the volume of the specimen remains constant and it remains cylindrical. !he following equations were used&

0ial strain 1 ε 3 @K(J(?

(?@initial length of sample 1cm3

$orrected area of cross section 103 @0?J-"

ε

0?@initial area of cross section of the sample 1cm63

0ial stress 1qu3 @#J0 1kgJcm6₃

#@aial load 1kg3

>raphs are plotted between aial strain1 ε 3 s aial stress1qu3,G of flyash and lime s aial stress and curing period S aial stress. !he maimum value of  aial stress is the unconfined compressive strength of soil sample.

Samples for conducting unconfined compression test were prepared using moulds of dimensions -?cm diameter, 6?cm height. Soil sample without additives were tested to find out the optimum moisture content based on compressive stress. In this study flyash is added in -6G and -G and lime :G and -?G respectively.

!he stress is applied and the deformation and load readings are noted until the specimen fails. !he maimum aial strain is noted.

Cali#ornia $earin/ sren/)

$alifonia state highway department developed the $alifornia bearing ratio test ,1$B%3test in -L+H for evaluating soil subgrade and base course materials for  fleible pavements. Must after =orld =ar 6,the F.S corps of ;ngineers adopted the $B% test for use in designing base courses for airfield pavements.

$alifornia bearing ratio1$B%3 is the ratio of force per unit area required to  penetrate a soil mass with a standard circular piston at the rate of -.6: mmJmin to that required for corresponding penetration in the standard material. (oad that has  been obtained from the test in crushed stone1Standard material3 is called standard load. !he standard material is said to have a $B% value of -??G.Smooth curves are plotted between penetration 1mm3 s load 1kg3.!he curve in most cases is concave upwards in the initial portions.0 correction is applied by drawing a tangent to the curve at the point of greatest slope from the corrected load  penetration graph obtained the loads at 6.:mm and :mm penetration. !he standard

loads for these penetrations can be taken from he table below&

San+ar+ loa+s #or CBR ess

#enetration depth 1mm3 Standard load 1kg3 Fnit load 1kgJcm63

6.: -+? ?

:.? 6?:: -?:

.: 6A+? -+

-? +-H? -A6

$B% value@ 1!est loadJStandard load3 -??

Samples for conducting $B% tests were prepared using moulds of  dimensions -:cm diameter and -.:cm height. !he weight of soil used is :kg  passing through 6?mm sieve. !he samples were prepared at 89$ and varying

lime and flyash.In this study, lime is added at -?G and fly ash at -G. Dire" s)ear es

!he shear strength of a soil is its maimum resistance to shear stresses 5ust before the failure. Shear failure of a soil mass occurs when the shear stresses induced due to the applied compressive loads eceed the shear strength of the soil. 'ailure in soil occurs by relative movements of the particles and not by breaking of particles. Shear strength is the principal engineering property which controls the stability of  the soil mass under loads. Shear strength determines bearing capacity of soils, stability of slopes of soils, earth pressure against retaining structure etc.

4irect shear test is conducted on a soil specimen in a shear bo which can split into two equal halves and is covered with porous grid plates on either sides. Normal load is applied for a constant stress and shear load is applied at a constant rate of  ?.?6 mmJminute. !he test is repeated for different stress and failure stress is noted. 0 failure envelope is obtained by plotting shear stress with different normal stress and is 5oined to form a straight line from which angle of shear resistance and cohesion is obtained.

S*e"i#i" /ra5i.

!he specific gravity of solid particles is defined as the ratio of the mass of a given volume of solids to the mess of an equal volume of water at ?_{$. Specific gravity}

of normal soils is between 6.A: to 6.H?. Specific gravity of soil mass indicates the average value of all the solid particles present in the soil mass. 0lso it is an

important parameter used for the determination of void ratio and particle size. Consisen". li,is

!he consistency of fine grained soil is the physical state in which it eists. It is used to denote the degree of firmness of soil. !he water content at which soil changes from one state to another is known as consistency limits.

0 soil containing high water is in the liquid state. It has no shear resistance and can flow like liquid. !herefore the shear strength is equal to zero. 0s the water  content is reduced, the soil becomes stiffer and starts developing resistance to shear  deformation. !he water content at which soil changes from liquid state to plastic state is known as liquid limit. !he liquid limit is find out by $asagrande7s liquid limit device. !he number of blows of this device is find out at different water  content. 'low curve is plot with number of blows on  ais and water content on y ais. !he water content corresponding to 6: blows is the liquid limit.

#lastic limit is the water content below which the soil stop behaving as a plastic material. It begins to crumble when rolled into a thread of soil of +mm diameter. 0t this water content , the soil loses its plasticity and passes to the semi"solid state. !he shear strength at the plastic limit ,is about -?? times that at the liquid limit.

CHAPTER 6

RESULTS AND DISCUSSIONS

!he following chapter covers the results of the testing programmes. !he results that are presented include soil properties admiture percentages and the various testing results for the soil additive combinations .

Nai5e soil *ro*eries an+ a+,i0!re *er"ena/es

Soil chacterstics were determined using atterberg limits ,hydrometer  analysis, specific gravity, standard proctor compaction and unconfined compression tests. !he test results is shown the table

Sl No& #roperties alues

- $B% value .+G

6 9a.dry density -:- kgJm+

content

 (iquid limit +AG

: #lastic limit 6AG

A #lasticity inde -?

!he grain size dirtribution curve for the soil used is shown in figure.

0 0.01 0.1 0 20 40 60 80 100 120

!he percentage of lime and fly ash for stabilization is determined from the unconfined compression test. !he test results are shown.

400

1950

2250

1800

1950

native soil lime 5% lime 10% fy ash 12% fyash 14%

!he native soil has an unconfined compression of ??kpa. !his increased by the addition of lime and fly ash. !he maimum strength is obtained by the addition of -?G lime and -G fly ash.

!he atterberg limit test results with various soil additive combination at different curing period are presented in the table and graphs showing variation of atterberg limits with curing period is plotted for different soil"additive combination.

Aer$er/ es res!ls on "la.-#l.as)-li,e ,i0!re

$uring period (iquid limit #lastic limit #lasticity inde

 Native soil +A 6A -? (ime&+ days 6: -: -?  days 6+ -H -? - days 66 6? : 'lyash&+ days +: -L -A  days +: 6+ -6 - days +: 6A L

2 4 6 8 10 12 14 16 0 5 10 15 20 25 30

liquid limit plastic limit plastcity index

2 4 6 8 10 12 14 16 0 5 10 15 20 25 30 35 40

liquid limit plastic limit plasticity index

!he native liquid limit and plasticity inde of the soil were +A and -?. !he #I values were reduced when they are mied with small amout of lime and became

nonplastic with the addition of more lime.'or clay"lime miture, the + day liquid limit is 6:, it reducese to 6+ for days and it becomes 66 at -days. !he plastic limit is increases from -: at +day to 6? at - days.0s the liquid limit decreases and  plastic limit increases the plasticity inde decreases from -? to : with curing

 period.

'or fly ash had more limited effect on the plasticity ofthese soils.!he liquid limit remains constant with curing period for the fly ash"clay miture.!he plastic limit increases from -L at +day to 6A at -days, as a liquid limit remains constant and  plastic limit increases, the plasticity inde values decreases from -A at +days to L at

- days.

A4IU DENSIT AND OPTIU OISTURE CONTENT

8ptimum moisture content and maimum density for native soil and each of the soil additive combination at different curing period is presented in the table and the variation of maimum density and optimum moisture content is plotted

Sl no& =ater content 4ry density

--H -L? 6 6? -:- + 66 -A  6 -6

ois!re-+ensi. relaions)i* #or "la.-#l.as) ,i0!res

+ days curing  days curing - days curing =ater 

content

4ry density =ater   content

4ry density =ater   content 4ry density -.- -+? -.H -6A? -+.+ L?? -.A -6? -:.+ -+?? - --+? -H.L -L? -A -+:? -.L -??? 6?.- -+H? -.6 -+-? -:.A H? 6?.: -+A? -H -6:? -:.L L??

0 5 10 15 20 25 30 35 40 0 500 1000 1500 2000 2500 native soil fyash 3days fyash days fyash14days !"#

ois!re-+ensi. relaions)i* o# "la.-li,e ,i0!res

+ days curing  days curing - days curing =ater 

content

4ry density =ater   content

4ry density =ater   content 4ry density 66 :? 6 +L? 6 -:? 6+ :L? 6: -? 6A 6?? 6 A: 6A : 6H 6+: 6: ::: 6 +L? +? 6?? 6A L? 6H +?? +6 -:L

0 5 10 15 20 25 30 35 40 0 500 1000 1500 2000 2500 native soil lime 3 days lime  days lime 14 days !"#

!he maimum density and optimum moisture content for the native soil are -:- kgJm+ _{and 6?G. =hen mied with fly ash the optimum moisture content}

and the maimum density is decreased.!he maimum density is -L? kgJm + at an optimum moisture content of -H.L G at + days.It is reduces to -???kgJm + _{at an}

optimum content of -.LG in - days. So both the maimum density and optimum moisture content decreases for fly ash"clay miture.

=hen mied with lime, the optimim moisture content is increased and the maimum dry density is decreased.!he maimum density is A: kgJm at an optimum moisture content of 6G in + days.In days the maimum density is : kgJm+ at an optimum moisture content of 6AG.!he maimum density is decreased to 6+: kgJm+ _{and optimum moisture content increased to 6HG.}

+ days curing  days curing - days curing  Normal stress 1kgJcm6₃ Shear  stress 1kgJcm6₃ Shear  stress 1kgJcm6₃ Shear stress 1kgJcm6₃  Native soil ?.: ?.L - ?.HL -.: ?.LL (ime& ?.: ?.:AL .6 ?.LL - .HL -.? -.6 -.: -.6 -.++ -.: 'ly ash& ?.: ?.:AL ?.:H- ?.AL: - ?.L- ?.LLH -.?--.: -.? -.6A -.+- 0.4 0.6 0.8 1 1.2 1.4 1.6 0 0.2 0.4 0.6 0.8 1 1.2 1.4 3 days cu$in  days cu$in 14 days cu$in &ative soil

0.4 0.6 0.8 1 1.2 1.4 1.6 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

3 days cu$in  days cu$in 14 days cu$in &ative soil

!he direct shear stresses of native soil for normal stress ?.: kgJcm6 _is

?.LkgJcm6.=hen mied with fly ash the direct shear stress increases to ?.:AL for  +days curing, ?.:H- for days curing and ?.AL: kgJcm6 _{for -days curing.}

=hen mied with lime, the direct shear stress increases to ?.:AL for +days curing, ?.6 for days curing and ?.LLkgJcm6 _{for - days curing.}

(oad penetration graph for native soil is given below&

$B%&(oad Openetration graph for clay"flyash mitures&

#enetration1mm 3

(oad1kg3

+ days curing  days curing - days curing

? ? ? ? ?.: .?- :.:: .L+ -L.+: -+.HA 6:.LL -.: 66.: 6:.LL ++.L6 6 ?.LH :+.?- A+.LH 6.: A6. -.H: H.H6 + A.HL L?.L6 L.L6 #enetration 1mm3 (oad 1kg3 ? ? ?.: +.+L - H.H -.: 6-.6 6 +H.-A 6.: :L.+A + AL.:+A  H6.6:A : HA.LA .: -?.ALA -? --.H6 -6.: -6.A:A

 HL.LL L.LA --.H : L:.LL -? -66.L: .: --:.LH -6L.?+ -:+.L -? -6A.+ --.L+ -A.H -6.: -+6.HL -:6.L -H:.6 0 2 4 6 8 10 12 14 0 20 40 60 80 100 120 140 160 180 200

clay-y ash mixture

$B% test values for clay"lime miture

#enetration1mm 3

(oad1kg3

+ days curing  days curing - days curing ? ? ? ? ?.: .6 A.LH L.+A --?.+: -:.A: 6-.6H -.: 6:.HH 6H.LL +.A 6 A.L6 :. A:.LA 6.: +.AHL L.?: H.LL + HL.H6 L:. -??.?- L: LL.L: --L.A : L.:- -?L.:L -6.H6 .: -6:.A6 -+.LH -:.H -? -+-.?A -L.A: -?.6--6.: -?.AL -:A.+6 -L?.L

0 2 4 6 8 10 12 14 0 50 100 150 200 250 3 days cu$in  days cu$in 14 days cu$in native soil CHAPTER 7

CONCLUSION