1

A

Project Report

On

“MODERN SOIL STABILIZATION TECHNIQUES”Submitted in Partial fulfilment for the award of the degree of

Bachelor of Technology

In

Civil Engineering

from

DIT UNIVERSITY, DEHRADUN

Guided By:- Submitted By:-

Mr. Subrata Mondal 1. Deepak Kumar(Asst. Professor) 1301011044

2. Pulkit Agrawal 1301011087

3. Aman Kansal 1301011010

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Contents1. Acknowledgement ………………………………...….…………….………….1

2. Introduction …………………………………………..…………….…………2

2.1. soil………………………………………………………………….………2

2.2. soil stabilization……………………………………………………….……2

2.3. Objective…………………………………………………………………....2

3. Principle of soil stabilization…………………………………………………..3

4. Advantages of soil stabilization……………………………………………….3

5. Methods of soil stabilization ………………………………………………….4

5.1. Mechanical…………………………………………………………………4

5.2. Chemical……………………………………………………………………5

5.3. Polymer/Alternatives……………………………………………………….6

6. Modern soil stabilization techniques…………………………………………6

6.1. Bitumen emulsion as soil stabilization……………………………………..6

6.2. Plastic as soil stabilizer……………………………………………………..7

6.3. Soil stabilization with rice husk ash and fly ash……………………………8

6.4. Electro-chemical stabilization………………………………………...........9

6.5. Cementation stabilization…………………………………………………10

7. Quality control & quality assurance………………………………………...12

7.1. Standard proctor compaction test…………………………………………12

7.2. CBR Test………………………………………………………………….13

7.3. Plate load test……………………………………………………………...14

8. Conclusion…………………………………………………………………….19

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ACKNOWLEDGEMENT

We have taken efforts in this project. However, it would not have been possible without the kind

support and help of many individuals and organization. We would like to extend our sincere

thanks to all of them.

We are highly obliged to Mr. Subrata Mondal (Asst. Professor) for their guidance and constant

supervision as well as for providing necessary information regarding the project & also for their

support in completing the project.

We would like to express our gratitude towards the member of Civil Department, DIT University

for their kind co-operation and encouragement which help us in completion of this project.

We would like to express our special gratitude and thanks to Dr. S.K TIWARI (HOD, Dept. of

civil Engineering, DIT University) for giving us such attention and time.

Our thanks and appreciations also go to my colleague in developing the project and people who

have willingly helped me out with their abilities.

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2. INTRODUCTION

For any land-based structure, the foundation is very important and has to be strong to support the entire structure. In order for the foundation to be strong, the soil around it plays a very critical role. So, to work with soils, we need to have proper knowledge about their properties and factors which affect their behavior. The process of soil stabilization helps to achieve the required properties in a soil needed for the construction work.

2.1. Soil:Naturally occurring materials that are used for the construction of all except the surface layers of pavements (i.e., concrete and asphalt) and that are subject to classification tests (ASTM D 2487) to provide a general concept of their engineering characteristics.

2.2. Soil stabilization:Stabilization in a broad sense incorporates the various methods employed for modifying the properties of a soil to improve its engineering performance. Stabilization is being used for a variety of engineering works, the most common application being in the construction of road and airfield pavements, where the main objective is to increase the strength or stability of soil and to reduce the construction cost by making best use of locally available materials.

2.3. Objective:There are following purposes for soil stabilization.

2.3.1. These include increasing the shear strength of an existing ground condition to enhance its load-bearing capacity.

2.3.2. Achieve a desired improved permeability.2.3.3. Enhancing the durability of the soil to resistance to the process of weathering, and

traffic usage among others.2.3.4. In wet weather, stabilization may also be used to provide a working platform for

construction operations. these types of soil quality improvement are referred to as soil modification

2.3.5. Thickness reduction : The strength and stiffness of a soil layer can be improved through the use of additives to permit a reduction in design thickness of the stabilized materials compared with an unsterilized or unbound material.

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3. PRINCIPLE OF SOIL STABILIZATIONSoil stabilisation means the improvement of stability or bearing capacity of the soil by the use of controlled compaction, proportioning and the addition of suitable admixture or stabilisers.

Evaluating the soil properties of the area under consideration. Deciding the property of soil which needs to be altered to get the design value and choose

the effective and economical method for stabilization. Designing the Stabilized soil mix sample and testing it in the lab for intended stability

and durability values

4. ADVANTAGESFollowing are the Advantages of using modern soil stabilization techniques

It Improves The Strength Of The Soil, Thus, Increasing The Soil Bearing Capacity.

It Is More Economical Both In Terms Of Cost And Energy To Increase The Bearing Capacity Of the Soil Rather Than Going For Deep Foundation Or Raft Foundation.

It Is Also Used To Provide More Stability To The Soil In Slopes Or Other Such Places.

Sometimes Soil Stabilization Is Also Used to Prevent Soil Erosion or Formation of Dust, Which is Very Useful Especially In Dry And Arid Weather.

Stabilization Is Also Done For Soil Water-proofing; This Prevents Water from Entering into The soil And Hence Helps the Soil from Losing Its Strength.

It Helps In Reducing the Soil Volume Change Due To Change in Temperature or Moisture content.

Stabilization Improves The Workability And The Durability Of The Soil.

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5. METHODS OF SOIL STABILIZATIONSDifferent types of soil stabilization have been performed for thousands of years; it wasn’t too

long after roads were developed that primitive engineers began looking for ways to improve

them.  Believe it or not, some of the original methods (or at least their spiritual descendants) are

still employed today.  Let’s take a look at the three basic types of soil stabilization and how they

work:

1. Mechanical

2. Chemical

3. Polymer/ Alternatives

5.1 Mechanical  The oldest types of soil stabilization are mechanical in nature.  Mechanical solutions involve

physically changing the property of the soil somehow, in order to affect its gradation, solidity,

and other characteristics.  Dynamic compaction is one of the major types of soil stabilization; in

this procedure a heavy weight is dropped repeatedly onto the ground at regular intervals to quite

literally pound out deformities and ensure a uniformly packed surface.  Vibratory compaction is

another technique that works on similar principles, though it relies on vibration rather than

deformation through kinetic force to achieve its goals. Types of Mechanical Soil Stabilization:

5.1.1. In-situ stabilization - The method involves on site soil improvement by applying

stabilizing agent without removing the bulk soil. This technology offer benefit of improving soils

for deep foundations, shallow foundations and contaminated sites. The technology can be

accomplished by injecting into soils a cementitious material such cement and lime in dry or wet

forms.

Depending on the depth of treatment, the in situ stabilization may be regarded as either

deep mixing method or mass stabilization.

Deep Mixing Method

The deep mixing method involves the stabilization of soils at large depth. It is an in situ ground

modification technology in which a wet or dry binder is injected into the ground and blended

with in situ soft soils (clay, peat or organic soils) by mechanical or rotary mixing tool. The aim is

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to produce the stabilized soil mass which may interact with natural soil and not, to produce too

stiffly stabilized soil mass like a rigid pile which may independently carry out the design load.

5.1.2. Wet Mixing

Applications of wet deep mixing involve binder turned into slurry form, which is then injected

into the soil through the nozzles located at the end of the soil auger. The method uses a crawler-

mounted, chainsaw-like mixing tool to blend in-situ soil with cementitious binder to create the

soil-cement wall. It further consists of a fixed post on which cutting, scratching teeth ride on a

rotating chain and injection ports deliver grout into treatment zone.

5.1.3. Dry Mixing

Dry mixing (DM) method is clean, quiet with very low vibration and produces no spoil for

disposal. It has for many years extensively used in Northern Europe and Japan.

The method involves the use of dry binders injected into the soil and thoroughly mixed with

moist soil. The soil is premixed using specialized tool during downward penetration, until it

reaches the desired depth.

5.1.4. Ex-situ stabilization

The technology involves dislodging of the soils and or sediments from the original position and

moves to other place for the purpose of amendment.

The main objectives of dredging can be either for amending the contaminated sediments to

reduce toxicity and mobility or to maintain or deepen navigation channels for the safe passage of

ships and boats. Offsite treatment of the sediment can be done in confined disposal facilities

(CDF) and then be used or disposed at designated site. Method of removal, means of

transportation, availability of treatment location, disposal site or demand for reuse is key factors

to consider when planning for ex-situ stabilization

5.2. Chemical Chemical solutions are another of the major types of soil stabilization.  All of these techniques

rely on adding an additional material to the soil that will physically interact with it and change its

properties.  There are a number of different types of soil stabilization that rely on chemical

additives of one sort or another; you will frequently encounter compounds that utilize cement,

lime, fly ash, chloride, sodium hydroxide or kiln dust.  Most of the reactions sought are either

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cementitious or pozzolanic in nature, depending on the nature of the soil present at the particular

site you are investigating.

The selection of type and determination of the percentage of additive to be used is dependent

upon the soil classification and the degree of improvement in soil quality desired. Generally,

smaller amounts of additives are required when it is simply desired to modify soil properties

such as gradation, workability, and plasticity.

5.3. Polymer/Alternative  Both of the previous types of soil stabilization have been around for hundreds of years, if not

more; only in the past several decades has technology opened up new types of soil stabilization

for companies to explore.  Most of the newer discoveries and techniques developed thus far are

polymer based in nature .These new polymers and substances have a number of significant

advantages over traditional mechanical and chemical solutions; they are cheaper and more

effective in general than mechanical solutions, and significantly less dangerous for the

environment than many chemical solutions tend to be.

6. MODERN TECHNIQUES Commonly used polymers for soil stabilization are:-

6.1. Bitumen Emulsion as soil stabilizer Types of emulsions:

A. O/W emulsion,

B. W/O emulsion,

Bitumen Emulsion is a 2-phase System Consisting of Bitumen, Water and Other Additives

• The bitumen is dispersed throughout the water phase in form of discrete globules, held in suspension by electrostatic charges stabilized by emulsifier

• The Emulsion contains 40-75% of bitumen,.1-2.5%emulsifier,25-60%water and other ingredients

• Typically of .1 – 50 µm in diameter.

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• It is mainly dark brown in color after breaking changes to black.

Why bitumen emulsion?

Primary Objective Is To Use For Road Surfacing Without Much Heating.

As main advantages this improves the handling of bitumen at room temperature.

Promotes surface interactions.

Its mixture with the aggregate attains full strength.

Economical and saves energy.

Reduced atmosphere pollution.

Water can also added before use to dilute as per requirement.

Rains can not affect it at the time of use and after use.

6.2. Plastic as soil stabilizerSoil stabilization is any process that so improves the physical properties of the soil, such as

increased shear strength, resilience, can be made suitable materials of cement, lime and fly ash as

controlled waste, etc. by compression or the use of additives costs for the introduction of these

additives has increased in recent years opened the door wide for the development of other types

of soil additives, such as plastic, bamboo, etc. effectively used this new technique of soil

stabilization to meet the challenges of society, to the waste, not to reduce the production of

valuable materials from waste makes sense. The use of plastic products such as plastic bags,

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bottles, etc. is increasing day by day leads to several environmental problems. Therefore disposal

of plastic waste without environmental hazards has become a real challenge. Therefore, the use

of plastic bottles is as a soil stabilizer is a useful, since there is no shortage of good quality soil

for embankments. This project involves the detailed study of the possible use of plastic bottles

waste for soil stabilization. The analysis has been filled by testing the cargo floor panels with

layers of plastic bottles with sand and halved bottle in the middle and a third tank positions

arranged reinforced executed. Comparing the test results showed that the cut centrally positioned

bottles were most effective in increasing the strength of the soil. The optimum proportion of the

plastic strip on the bottom was found by CBR test and use this percentage of plastic, plate load

test was also performed. The size and content of the shredded waste plastic bottles have a

significant impact on the improvement of the soil strength.

Fig: Plastic as soil stabilization

6.3. Soil stabilization with rice husk ash and fly ashFly ash and rice husk ash has been used successfully in many projects to improve the strength

characteristics of soils. Fly ash can be used to stabilize bases or subgrades, to stabilize backfill to

reduce lateral earth pressures and to stabilize embankments to improve slope stability. Typical

stabilized soil depths are 15 to 46 centimeters (6 to 18 inches). The primary reason fly ash is

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used in soil stabilization applications is to improve the compressive and shearing strength of

soils. The compressive strength of fly ash treated soils is dependent on:

In-place soil properties

Delay time

Moisture content at time of compaction

Fly ash addition ratio

Fig: Mixing and shaping of fly ash stabilized soil Fig: Compaction of fly ash stabilized soil.

6.4. Electrochemical stabilization Suitable electrolyte conditioning at the electrodes greatly facilitates the transport of desired ions

through soil, enhancing the ability of electro kinetic processes to stabilize the soil through

cementing reactions. Cationic species are injected at the anode, and anionic species at the

cathode, with suitable electrolyte conditioning. For example, if acid or base formation negatively

affects transport, chemical conditioning is used to neutralize the acid or base products of

electrolysis. Ionic species can be transported through soil at rates of several centimeters a day,

even in soils such as clays having a low hydraulic conductivity. Electroosmotic transport can be

minimized by appropriate conditioning of the pore fluid chemistry. For example, placement of

chemical conditioners with smaller cations at the anode compartment and larger anions at the

cathode compartment, or increasing the ion content of the pore fluid (e.g. by acidification) can

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help minimize electroosmotic transport and any of its adverse effects on species transport. The

cations and anions are preferably selected to form cementatious precipitates in the soil. Thus

when cationic species are injected at the anode and anionic species are injected at the cathode,

stabilization reactions can prevail in the soil as the result of cross-transport of species, and a

homogenous and uniform cementation and stabilization can be achieved in a short time.

Fig: electrochemical soil stabilization

6.5. Cementation stabilization Cementation consists of injecting a cement suspension into the soil to be stabilized through a

system of boreholes drilled in the soil. The suspension has a mass ratio of cement to water in the

range of 0.1-2. to increase the mobility of dense cement solution and cement sand solution

sulphite alcohol vinasse can be added in the amount of 0-0.25% of the quantity of cement.

addition of calcium chloride in the amount of 1-5% of the quantity of cement, can be used to

regulate the acceleration of setting of the solution and increasing the initial strength of cement

stones. The stability of soil and its water tightness increases significantly after cementation.

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Hot bituminization, as well as cementation, is used in carvenous rocky strata where surface flow attains a high speed. This method is used for very narrow fissures in rocky soil and for stabilization for sandy soil

Fig: cementation stabilization

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7. QUALITY CONTROL AND QUALITY ASSURANCEThe various tests conducted on the soil sample are the following:

Standard proctor compaction test CBR test Plate load test

Finally the above tests were conducted on plain soil sample to determine it’s properties. Thereafter any one of the above treatment is done as per the requirement of soil to stabilize it. And finally above tests will be conducted on the soil sample to investigate the change in the properties. The detailed procedure of each test is discussed below:-

7.1. Standard proctor compaction test

7.1.1. SCOPE

This method covers the determination of the relationship between the moisture content and density of soils compacted in a mould of a given size with a 2.5 kg rammer dropped from a height of 30 cm.

7.1.2. APPARATUS1. Proctor mould having a capacity of 944 cc with an internal diameter of 10.2 cm and a

height of 11.6 cm. The mould shall have a detachable collar assembly and a detachable base plate.

2. Rammer: A mechanical operated metal rammer having a 5.08 cm diameter face and a weight of 2.5 kg. The rammer shall be equipped with a suitable arrangement to control the height of drop to a free fall of 30 cm.

3. A balance of 15 kg capacity.

4. Straight edge.5. Graduated cylinder.6. Mixing tools such as

mixing pan, spoon, towel, spatula etc. Fig: test equipment for proctor test

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7.1.3. PROCEDURE

1. Take a representative oven-dried sample, approximately 5 kg in the given pan. Thoroughly mix the sample with sufficient water to dampen it to approximately four to six percentage points below optimum moisture content.

2. Weigh the proctor mould without base plate and collar. Fix the collar and base plate. Place the soil in the Proctor mould and compact it in 3 layers giving 25 blows per layer with the 2.5 kg rammer falling through.

3. Remove the collar, trim the compacted soil even with the top of the mould by means of the straight edge and weigh.

4. Divide the weight of the compacted specimen by 944 cc and record the result as the wet weight in grams per cubic centimeter of the compacted soil.

5. Remove the sample from the mould and slice vertically through and obtain a small sample for moisture determination.

6. Thoroughly break up the remainder of the material until it will pass a no.4 sieve as judged by the eye. Add water in sufficient amounts to increase the moisture content of the soil sample by one or two percentage points and repeat the above procedure for each increment of water added. Continue this series of determination until there is either a decrease or no change in the wet unit weight of the compacted soil.

7.2. CBR test

7.2.1. OBJECTIVE

To determine the California bearing ratio by conducting a load penetration test in the laboratory. 

7.2.2. APPARATUS

1. Cylindrical mould with inside dia 150 mm and height 175 mm, provided with a detachable extension collar 50 mm height and a detachable perforated base plate 10 mm thick. 

2. Spacer disc 148 mm in dia and 47.7 mm in height along with handle. 

3. Metal rammers. Weight 2.6 kg with a drop of 310 mm (or) weight 4.89 kg a drop 450 mm. 

4. Weights. One annular metal weight and several slotted weights weighing 2.5 kg each, 147 mm in dia, with a central hole 53 mm in diameter. 

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5. Loading machine. With a capacity of at least 5000 kg and equipped with a movable head or base that travels at an uniform rate of 1.25 mm/min. Complete with load indicating device. 

6. Metal penetration piston 50 mm dia and minimum of 100 mm in length. 

7. Two dial gauges reading to 0.01 mm. 

8. Sieves. 4.75 mm and 20 mm I.S. Sieves.

9. Miscellaneous apparatus, such as a mixing bowl, straight edge, scales soaking tank or pan, drying oven, filter paper and containers. 

7.2.3. THEORY

It is the ratio of force per unit area required to penetrate a soil mass with standard circular piston at the rate of 1.25 mm/min. to that required for the corresponding penetration of a standard material.

C.B.R. = Test load/Standard load 100

The following table gives the standard loads adopted for different penetrations for the standard material with a C.B.R. value of 100%

Penetration of plunger    (mm) Standard load    (kg)2.5

5.0

7.5

10.0

12.5

1370

2055

2630

3180

3600

          The test may be performed on undisturbed specimens and on remoulded specimens which may be compacted either statically or dynamically. 

7.2.4. PROCEDURE

1. Normally 3 specimens each of about 7 kg must be compacted so that their compacted densities range from 95% to 100% generally with 10, 30 and 65 blows.

2. Weigh of empty mould3. Add water to the first specimen (compact it in five layer by giving 10 blows per layer)4. After compaction, remove the collar and level the surface.5. Take sample for determination of moisture content.

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6. Weight of mould + compacted specimen.7. Place the mold in the soaking tank for four days (ignore this step in case of

unsoaked CBR.8. Take other samples and apply different blows and repeat the whole process.9. After four days, measure the swell reading and find %age swell.10. Remove the mould from the tank and allow water to drain.11. Then place the specimen under the penetration piston and place surcharge load of 10lb.12. Apply the load and note the penetration load values.13. Draw the graphs between the penetration (in) and penetration load (in) and find the value

of CBR.14. Draw the graph between the %age CBR and Dry Density, and find CBR at required

degree of compaction.

7.3. Plate load test

7.3.1. OBJECTIVE

To perform plate load test to obtain a load-settlement curve of a soil at a particular depth so as to estimate the ultimate bearing capacity a foundation.

7.3.2. APPARATUS

1. Test plate of square size (300 mm or 450 mm or 600 mm or 750 mm)2. Hydraulic jack (50 T capacity)3. Hydraulic pump (50 T capacity)4. Pressure gauge (to read 50 T load with a sensitivity of 0.5 T)5. Proving ring or load cell (50 T capacity)6. 4 no of dial gauges (with sensitivity of 0.01 mm and a travel of 50 mm)7. Loading columns8. Dial gauge supporting channels9. Dial gauge stands10. Magnetic bases for dial gauges11. Loading platform equipment (girders, plates, sand bags etc.) or Truss with anchor rods12. Plum bob13. Sprit level14. Tripod (to erect the platform or truss frame)15. Pulley block (to lift the girders or truss frame)

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7.3.3. PROCEDURE

1. Excavate the test pit. The test pit size should be 5 times the size of test plate (Bp) and depth equal to the depth of foundation.

2. The loading platform should be erected over the test pit such that, the vertical line drawn through the center of gravity of the load passes through the centroid of the base of the test pit. This can be achieved by positioning the reaction girder (truss) with the help of the plum bob and spirit level. The load over the platform should be at least 50% more than the anticipated load to be transferred on the plate. This will ensure the safety of the platform for any small shift of the CG of the loading platform from the vertical axis of the pit.

3. Position the test plate centrally at the base of the pit. Ensure that the ground surface below the test plate is perfectly horizontal and level so that no stress concentration takes place below the plate during loading. If the ground surface is slightly uneven a thin layer of sand is spread underneath the test plate.

4. Position the hydraulic jack over the plate so that when hydraulic pressure is built up the jack pushes against the loading platform. If require place a loading column between the test plate and the jack to ensure the jack reach the loading platform.

5. Position minimum of two dial gauges diagonally at the corners (preferably 4 at all corners of the test plate) to record its settlement of the plate. The dial gauges should be supported carefully over a stable base which does not settle with the plate. This can be achieved by placing two cross beams at ground level over which the dial gauges are supported with the help of magnetic bases. The settlement of the plate is transmitted to the dial gauges through dial gauge stands.

6. The dial gauges should be positioned such that the plunger of the dial gauges is at its beginning of rebound (i.e. the plunger is initially pushed up) so that it will get released as the plate settles and the reading changes and the difference in reading provided the settlement of the plate.

7. The load is applied on the plate by pumping the hydraulic pressure into the jack. The upward movement of the plunger of the jack tries to push the loading platform up. Since the pressure built up in the jack (say 1 or 2 T) is much less than the load on the platform, the pressure in the jack will push the test plate down by taking the loading platform (say 30 to 40 T) as rigid support. This is a case similar to the expansion of a system between two supports. Due to the expansion the weaker support (ground) yields.

8. Apply a seating load of 0.7 T/m2 which is released before the actual loading is started.9. Note the initial readings of the dial gauges.10. The load is applied through the hydraulic jack in convenient increments. The load

increments may be one fifth of the expected safe bearing capacity or one-tenth of the ultimate bearing capacity or any other smaller loads. The applied load is read either from the pressure gauge fitted to the hydraulic pump or from the proving ring fixed between the jack and the reaction platform.

11. Settlement of the plate is observed from the dial gauge readings. Settlement should be observed for each increment of load after 1, 4, 10, 20, 40 and 60 minutes and thereafter at

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hourly interval until the rate of settlement becomes less than about 0.02 mm per hour. Enter the readings in the tabular form.

12. After completing the recording of settlement readings under a load, the next load increment is applied and the dial gauges readings are noted under the new load.

13. The loading increments and the recording of the settlements under each load are continued until the maximum load is reached. The maximum load that is to be applied corresponds to 1.5 times the estimated ultimate load or to 3 times the proposed allowable bearing pressure.

7.3.4. OBSERVATIONS AND CALCULATIONS

The load intensity and settlement observation of the plate load test are plotted. The figure shown

below (Fig-3) shows a set of typical load settlement curves. The ultimate bearing capacity is

taken as the load at which the plate starts sinking at a rapid rate, i.e. when the curve drops down

to a vertical line. From figure 3 it can be observed that in dense sand or stiff clays the failure is

not pronounced. In such cases a plot of load and settlement, both being taken in logarithmic

scales, gives two straight lines. The intersection of these lines is taken as the ultimate bearing

capacity of soil (see fig.).

Fig: Arrangement of plate load test

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Fig: load settlement curve

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8. CONCLUSIONThe use of modern soil stabilization techniques has significantly helped in ground improvement.This new technique of soil stabilisation can be effectively used to meet the challenges of society, producing useful material from non-useful waste materials.

It can significantly enhance the properties of the soil used in the construction of road and infrastructures. Results include a better and longer lasting road and structures with increased loading capacity.

This project is really helpful in improving our practical skills as well as our technical knowledge on the topic.