A Study on Effect of Blast Furnace Slag in Road Subgrade Layer

8/12/2019 A Study on Effect of Blast Furnace Slag in Road Subgrade Layer

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A Study on Effect of Blast Furnace Slag in Road Subgrade Layer

Dept. of Civil Engineering, NMIT Page 1

Chapter 1

Introduction

1.1 GeneralTransport is an important infrastructure for development of any country. It contributes

to the economic, industrial, social and cultural development of any country. It is regarded as

an index of economic and it may be said that the increased productivity and its efficient

transportation can lower the cost of production. Transportation system penetrates in to all

phases of production and distribution.

Economic development of any country is controlled to a great extent by the highway

and airport networks. This is becoming particularly apparent in the developing countries,

where tremendous lengths of roads need to be constructed in order to facilitate the

development of agriculture, commerce and industry. The cost of any road pavement project

includes initial costs and subsequent maintenance costs. The initial costs include many items

such as land, accommodation works, bridges and subways, drainage, pavement construction

etc. The type and the thickness of the pavement construction determines, a large percentage

of the initial cost of any road project. Therefore, the development and use of methods to

decrease the cost of pavement construction is very beneficial. It is essential to take into

consideration the conditions of the subgrade soil before designing the type and the thickness

of the pavement, as the subgrade carries the traffic loads as well as the pavement loads.

The major function of the pavement is to reduce stresses in the subgrades so that there

is little or no deformation in the subgrade. Therefore, the more the subgrade is resistant to

deformation the thinner the pavement will be, thus reducing the construction cost of the road.

Good quality subgrade soils are preferable for durable roads but are not always

available for highway construction. The highway engineer designing a road pavement may be

faced by weak or unsuitable subgrade. In this case the following methods to overcome this

problem can be considered. Firstly, improve the in-situ materials by normal compaction

methods and design for the modified properties. Secondly, import suitable materials from the


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nearest convenient source and replace the site materials. Thirdly, improve the properties of

the existing materials by incorporating some other materia ls; this process is known as "soil

stabilisation"

The most appropriate method will usually be determined by economic considerations,for example it may be cheaper to stabilise a soil using relatively expensive additives rather

than excavate and dispose of unsuitable materials and import and place suitable fill, as well

as the properties of the subgrade.

1.2 Pavement

A pavement is a structure consisting of superimposed layers of processed materials

above the natural soil sub-grade, whose primary function is to distribute the applied vehicleloads to the sub-grade. The pavement structure should be able to provide a surface of

acceptable riding quality, adequate skid resistance, favourable light reflecting characteristics,

and low noise pollution. The ultimate aim is to ensure that the transmitted stresses due to

wheel load are sufficiently reduced, so that they will not exceed bearing capacity of the sub-

grade.

The main purpose of a highway pavement is to provide a satisfactory surface upon

which highway vehicles can operate. The term pavement ordinarily means the surfacing layer

only. But in highway design, it means the total thickness of road including surfacing, base

and sub-base, if any. Thus the term pavement includes all the structural layers of road

structure lying on the sub-grade of the road.

1.2.1 Functions and Desirable Characteristics of Pavement

A highway pavement is designed to support the wheel loads imposed on it from

traffic moving over it. Additional stresses are also imposed by changes in the environment. It

should be strong enough to resist the stresses imposed on it and it should be thick enough to

distribute the external loads on the earthen sub-grade, so that the sub-grade itself can safely

bear it.

For satisfactory performing the above functions, the pavement should have many desirable

characteristics. These are,


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It should be structurally sound enough to withstand the stresses imposed on it. It should be sufficiently thick to distribute the loads and stresses to safe value on the

sub-grade soil.

It should provide a reasonably hard wearing surface, so that the abrading action ofwheels does not damage the surface.

It should be dust-proof so that traffic safety is not impaired. Its riding quality should be good. It should be smooth enough to provide comfort to

the road users at the high speeds at which modern vehicles are driven.

The surface of the pavement should develop as low a friction with the tyres aspossible. This will enable the energy consumption of the vehicles to be low.

The surface of the pavement should have a texture and adequate roughness to preventskidding of vehicles.

The surface should not produce excessive levels of sound from moving vehicles. The surface should be impervious so that water does not get into the lower layers of

the pavement and the sub-grade and cause deterioration.

The pavement should have a long life and the cost of maintaining it annually shouldbe low.

1.2.2 Requirements of a Pavement

An ideal pavement should meet the following requirements:

Sufficient thickness to distribute the wheel load stresses to a safe value on the sub-grade soil.

Structurally strong to withstand all types of stresses imposed upon it. Adequate coefficient of friction to prevent skidding of vehicles. Smooth surface to provide comfort to road users even at high speed. Produce least noise from moving vehicles.


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Dust proof surface so that traffic safety is not impaired by reducing visibility. Impervious surface, so that sub-grade soil is well protected. Long design life with low maintenance cost.

1.2.3 Types of Pavements

Based on the structural behaviour, pavements are generally classified in to two categories:

Flexible pavements Rigid pavementFlexible pavements are those, which on the whole have a low or negligible flexural

strength and are rather flexible in their structural action under the loads. The flexible

pavement layers reflect the deformation of the lower layers on to the surface of the layer.

Thus if the lower layer of the pavement or soil sub-grade is undulated, the flexible pavement

surface also gets undulated.

Rigid pavements are those which possess note worthy flexural strength or flexural rigidity.

The stresses are not transferred from grain to grain to the lower layers as in the case of

flexible pavement layers. The rigid pavements are made of Portland cement concrete-either

plain, reinforced or pre-stressed concrete. The rigid pavement has the slab action and is

capable of transmitting the wheel load stresses through a wider area below. The cement

concrete pavement slab can very well serve as a wearing surface as well as effective base

course. Therefore usually the rigid pavement structure consists of a cement concrete slab,

below which a granular sub-base course may be provided. Providing a good base or sub-base

course layer under the cement concrete slab, increases the pavement life considerably and

therefore works out more economical in the long run.

1.3 Components of Flexible Pavement

A typical flexible pavement consists of four components soil sub-grade, sub-base

course, base course and surface course.


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1.3.1 Sub-grade

Fig 1.1Typical cross section of road

Soil is the cheapest and most widely used material in any highway system. The

supporting soil beneath pavement and its special under courses is called sub grade. The word

sub-grade refers to the in-situ materials under the pavement structures. Sub-grade properties

can be overriding factors to the pavement performance, and it is vital to investigate the sub-

grade material characteristics thoroughly to design a pavement with adequate service life.

Undisturbed soil beneath the pavement is called natural sub grade. Compacted sub grade is

the soil compacted by controlled movement of heavy compactors.

1.3.1.1 Desirable Properties

The desirable properties of sub grade soil as a highway material are

Stability Incompressibility Permanency of strength


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Minimum changes in volume and stability under adverse conditions of weather andground water

Good drainage, and Ease of compactionIn this report, the tests used to determine the sub-grade engineering properties, the

techniques used to analyze the sub-grade, as well as the common failure modes of the

pavement sub-grades are introduced.

1.3.2 Sub-Base Course

The sub-base course is the layer of material beneath the base course and the primary

functions are to provide structural support, improve drainage, and reduce the intrusion of

fines from the sub-grade in the pavement structure. If the base course is open graded, then the

sub-base course with more fines can serve as filler between sub-grade and the base course.1.3.3 Base Course

The base course is the layer of material immediately beneath the surface of binder

course and it provides additional load distribution and contributes to the sub-surface

drainage. It may be composed of crushed stone, crushed slag, and other untreated or

stabilized materials.

1.3.4 Surface Course

Surface course is the layer directly in contact with traffic loads and generally contains

superior quality materials. They are usually constructed with dense graded asphalt concrete.

The functions and requirements of this layer are,

It provides characteristics such as friction, smoothness, drainage, etc. Also it willprevent the entrance of excessive quantities of surface water into the underlying base,

sub-base and sub-grade.


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It must be tough to resist the distortion under traffic and provide a smooth and skid-resistant riding surface.

It must be water proof to protect the entire base and sub-grade from the weakeningeffect of water.

Flexible pavements will transmit wheel load stresses to the lower layers by grain-to-grain

transfer through the points of contact in the granular structure. The wheel load acting on the

pavement will be distributed to a wider area, and the stress decreases with the depth. Flexible

pavement may be constructed in a number of layers and the top layer has to be of best quality

to sustain maximum compressive stress, in addition to wear and tear. The lower layers will

experience lesser magnitude of stress and low quality material can be used.

1.4 Blast Furnace Slag

In the production of iron, iron ore, iron scrap, and fluxes (limestone or dolomite or

both) are charged into a blast furnace along with coke for fuel. The coke is combusted to

produce carbon monoxide, which reduces the iron ore to a molten iron product. This molten

iron product can be cast into iron products, but is most often used as a feedstock for steel

production.

Blast furnace slag is a nonmetallic coproduct produced in the process. It consists

primarily of silicates, aluminosilicates, and calcium-alumina-silicates. The molten slag,

which absorbs much of the sulfur from the charge, comprises about 20 percent by mass of

iron production. Figure 1.2 presents a general schematic, which depicts the blast furnace

feedstocks and the production of blast furnace coproducts (iron and slag).

Different forms of slag product are produced depending on the method used to cool

the molten slag. These products include air-cooled blast furnace slag (ACBFS), expanded or

foamed slag, pelletized slag, and granulated blast furnace slag.


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Fig 1.2General schematic of blast furnace operationand blast furnace slag production

Fig 1.3Blast Furnace


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1.4.1 Types of Blast furnace slag

1.4.1.1 Air-Cooled Blast Furnace Slag

Fig 1.4Air-Cooled Blast Furnace Slag

If the liquid slag is poured into beds and slowly cooled under ambient conditions, a

crystalline structure is formed, and a hard, lump slag is produced, which can subsequently be

crushed and screened.

1.4.1.2 Expanded or Foamed Blast Furnace Slag

Fig 1.5 Expanded or Foamed Blast Furnace Slag

If the molten slag is cooled and solidified by adding controlled quantities of water,

air, or steam, the process of cooling and solidification can be accelerated, increasing the

cellular nature of the slag and producing a lightweight expanded or foamed product. Foamed

slag is distinguishable from air-cooled blast furnace slag by its relatively high porosity and

low bulk density.

1.4.1.3 Pelletized Blast Furnace Slag


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Fig 1.6 Pelletized Blast Furnace Slag

If the molten slag is cooled and solidified with water and air quenched in a spinning

drum, pellets, rather than a solid mass, can be produced. By controlling the process, the

pellets can be made more crystalline, which is beneficial for aggregate use, or more vitrified

(glassy), which is more desirable in cementitious applications. More rapid quenching results

in greater vitrification and less crystallization.

1.4.1.4 Granulated Blast Furnace Slag

Fig 1.7 Granulated Blast Furnace Slag

If the molten slag is cooled and solidified by rapid water quenching to a glassy state,

little or no crystallization occurs. This process results in the formation of sand size (or frit-

like) fragments, usually with some friable clinkerlike material. The physical structure and

gradation of granulated slag depend on the chemical composition of the slag, its temperature

at the time of water quenching, and the method of production. When crushed or milled to

very fine cement-sized particles, ground granulated blast furnace slag (GGBFS) has

cementitious properties, which make a suitable partial replacement for or additive to Portland

cement.


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1.5 Material composition

BFS is chemically and mineralogically more consistent than naturally occurring

aggregates. It consists primarily of the silicates and aluminosilicates of calcium and

magnesium together with other compounds of sulphur, iron, manganese and other trace

elements.

When ground to the proper fineness, the chemical composition and glassy

(noncrystalline) nature of vitrified slags are such that when combined with water, these

vitrified slags react to form cementitious hydration products. The magnitude of these

cementitious reactions depends on the chemical composition, glass content, and fineness of

the slag. The chemical reaction between GGBFS and water is slow, but it is greatly enhanced

by the presence of calcium hydroxide, alkalies and gypsum (CaSO4).

Table 1.1 Typical composition of blast furnace slag

Constituent

Percent(%)

1949 1957 1968 1985

Mean Range Mean Range Mean Range Mean Range

Calcium Oxide (CaO) 41 34-48 41 31-47 39 32-44 39 34-43

Silicon Dioxide (SiO2) 36 31-45 36 31-44 36 32-40 36 27-38

Aluminum Oxide (Al2O3) 13 10-17 13 8-18 12 8-20 10 7-12

Magnesium Oxide (MgO) 7 1-15 7 2-16 11 2-19 12 7-15

Iron

(FeO or Fe2O3) 0.5 0.1-1.0 0.5 0.2-0.9 0.4 0.2-0.9 0.5 0.2-1.6

Manganese Oxide

(MnO)0.8 0.1-1.4 0.8 0.2-2.3 0.5 0.2-2.0 0.44 0.15-0.76

Sulfur

(S)1.5 0.9-2.3 1.6 0.7-2.3 1.4 0.6-2.3 1.4 1.0-1.9


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Chapter 2

Aim and Scope of the Project

2.1 Aim

Effect of mixing different percentage of Blast furnace slag on CBR value ofsubgrade soil.

Environment friendly disposal of slag. To contribute towards the sustainable development of road infrastructure. To reduce the construction material cost. Environmental aspects of usage of slag in road construction.

2.2 Scope

Pavements are constructed on roads for the safe and comfortable movements of

various types of vehicle at the desired speed. All these pavements are laid over a prepared

soil surface called sub-grade. Therefore it is necessary first to test the properties of the sub-

grade soil and to construction of pavements. The basic tests needed on the sub-grade soil for

this purpose are for the soil, its density and compaction characteristics of the sub-grade for

the design of pavements.

In this project an attempt will be made to replace the ordinary conventional subgrade

material like laterite soil with certain percentage of Blast Furnace slag to reduce the material

cost and to improve the strength of the subgrade. The attempt also involves effective disposal

of the slag materials in environmentally friendly manner.


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Chapter 3

Literature Review

3.1 General

Yildirim I. Z, [1] The main objectives of this research were to determine the

geotechnical engineering properties of two types of steel slag generated from different

steelmaking operations and to assess their potential use in subgrade stabilization and

embankment construction. Samples of fresh and aged basic-oxygen-furnace (BOF) slag and

of fresh electric-arc-furnace-ladle (EAF(L)) slag were characterized through a series of

laboratory tests (specific gravity, grain-size analysis, X-ray diffraction, compaction,

maximum and minimum density, large-scale direct shear, consolidated drained triaxial and

swelling tests).The effects of gradation on the engineering properties of both fresh and aged

steel slag samples were also investigated

Sanjay Kumar, [2]This paper is an overview on the utilisation of solid wastes with

focus on blast furnace slag, red mud and fly ash generated in large quantities from iron and

steel industry; primary aluminium production and coal fired power plants, respectively.

Innovative methodologies, based on the recent research by the authors, are highlighted and

these include: (a) smelting reduction of red mud to produce pig iron and titania rich slag, (b)

mechanical activation of the slag and fly ash to prepare improved blended cements in terms

of higher usage of waste and enhanced cement properties, (c) synergistic usage of fly ash,

blast furnace slag and iron ore tailings in the preparation of floor and wall tiles and (d)

preparation of synthetic granite from fly ash as a value added product.

Koteswara Rao. D, [3] The problems with expansive soils have been recorded all

over the world. In monsoon they imbibe water and swell and in summer they shrink on

evaporation of water there from. Because of this alternative swelling and shrinkage lightly

loaded civil engineering structures like residential buildings, pavements and canal linings are

severely damaged. It is, therefore, necessary to mitigate the problems posed by expansive

soils and prevent cracking of structures. Many innovative foundation techniques have been

devised as a solution to the problem of expansive soils. The chief among them are sand

cushion technique, cohesive non-swelling (CNS) layer technique and under reamed piles.


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Stabilization of expansive clays with various additives has also attained lot of success. The

various additives used for stabilizing expansive soils are lime, calcium chloride, fly ash,

GBFS, gypsum, rice husk ash and others. Experiments were done to find out all

characteristics of these materials and the mix of the stratified embankment materials. The fly

ash, through its pozzolanic activity gave an improved strength and the cohesive soil gave

enough cohesion for slope stability and to resist erosion. The use of GBFS in the mix ensured

higher strengths.

R. M. Nidzam, [4] This paper reviews a relatively recent approach towards

sustainable soil stabilisation, by utilising ground granulated blastfurnace slag, an industrial

by-product from steel manufacture. It describes in detail the reactions and reaction

mechanisms that occur when soil modification and subsequent stabilisation processes take

place. The effects of incorporating slag in the soil stabilisation process on the engineering

properties of a soil are also reviewed and discussed. The review demonstrates the great

potential of slag in soil stabilisation, in particular of the sulfate-bearing soils whose

stabilisation using the traditional stabilisers of lime and/or Portland cement leads to excessive

swelling.

Hongzhi Cui, [5] Ground granulated blast-furnace slag (GGBS) is a residue of steel

production. It is a latent hydraulic binder and is normally used to improve the durability of

concrete and mortars; at the same time, for the global environment, GGBS displays

pozzolanic reactions and replacement of Portland cement can effectively reduce CO2

emissions in the cement industry; therefore, many research projects investigate the properties

of concrete with GGBS. Song and Saraswathys study showed that GGBS in concrete

reduced heat evolution increased the compressive strength at later ages, decreased chloride

ion penetration and increased resistance to sulphate attack and alkali-silica reaction. In fact,

among the research, there is not many reports of the properties of lightweight aggregate

concrete (LWAC) with GGBS.

Zhulai Wang, [6] In order to solve disposal problem of solid waste, blast furnace

slag (BFS) and sewage sludge (SS) were tested as components for producing ceramsite. This

study investigated the feasibility of that at different preheating and sintering temperature and

duration and different mass ratios (BFS: SS: clay).The results show that the optimal

preheating temperature and duration were 400C and 20 min and that of sintering were


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1000C and 20 min. When the content of BFS increased and that of SS declined, the bulk and

apparent density gradually increased while the 1 h water adsorption rate relatively decreased.

The ceramsite produced had very good characteristics of solidifying heavy metal and the

values of Cd, Cr and Sn met China national standard (GB5085.3-2007); the leaching dose of

heavy metals reached minimum at 1100C. With the increasing of sintering temperature and

duration, the gas was gradually released from the ceramsite to form many pores and the glass

phase and smooth surface appeared in the ceramsite. The turning point of sintering

temperature and duration were 1000C and 20 min. The conclusions reveal that it is feasible

to produce ceramsite by using blast furnace slag and sewage sludge.

Ch. Nageshwar Rao, [7]The performance of pavements depends to a large extent on

the strength and stiffness of the subgrades. Among the various methods of evaluating the

subgrade strength, the use of portable falling weight deflectometers (PFWD) is gaining

popularity in the recent years. This is due to its simplicity in design, portability, and the

added advantages of providing quick and reliable estimates of the Youngs modulus of

elasticity of pavement subgrades. Hence it was felt that there is a need to study the

correlation between results obtained using the PFWD and those obtained using the

traditional approaches such as the California bearing ratio (CBR) test, the dynamic cone

penetrometer (DCP) test. The work described herein focuses on exploring the correlations

between the results obtained using the PFWD, and the results obtained using the CBR

method and DCP for lateritic soils at various locations of Dakshina Kannada district of the

State of Karnataka, India. Regression models were developed as part of this study to enable

the prediction of CBR values based on the average of observed values of the Youngs

modulus obtained using the PFWD (Epfwd), and prediction of Epfwd from the average

penetration-rates of DCPs performed for field density, and field-moisture content.

Wei-Hsing Huang , [8]This research assessed those properties of power plant bottom

ash likely to affect its use as highway fill or pavement material, based on laboratory

investigation con-ducted on eleven Indiana bottom ashes. Laboratory tests included:

chemical analysis, mineralogical study, microscopic examination of ash particles, specific

gravity, grain size distribution, sulfate soundness, Los Angeles abrasion, permeability, shear

strength, moisture-density relations, degradation under compaction, compressibility, and


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California bearing ratio. The various test values and properties were compared to- those of

representative granular soils or appropriate specifications. These comparisons provide

information necessary for judging the suitability of bottom ash in Indiana highway

construction. The potential environmental effects of bottom ash utilization were evaluated

by performing leaching tests outlined in the EP toxicity test and an Indiana leaching method.

Chemical analysis of the leachates showed that bottom ash is nonhazardous, and its effects

on the quality of'ground water are minimal.


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Chapter4Materials and Methodology

4.1 Materials

The materials involved in our project work are laterite soil and additive called Blast

furnace slag. In our project we studied the California bearing ratio study by the addition of

admixtures in detail.

4.1.1 Collection of Materials

As per the requirement of our project we collected the soil from a site sulliapadav.

The Blast furnace slag required for the is collected from kairali steel plant pallakad.

4.2 Experimental Methodologies

To study the different properties of soil before and after the addition of admixtures i.e

Blast furnace slag, Soil, following laboratory tests were conducted.

4.2.1 Atterberg Limits

The Atterberg limits are a basic measure of the nature of a fine-grained soil.

Depending on the water content of the soil, it may appear in four states: solid, semi-solid,

plastic and liquid. The Atterberg limits can be used to distinguish between silt and clay, and

it can distinguish between different types of silts and clays. These limits were created by

Albert Atterberg, a Swedish chemist. They were later refined by Arthur Casagrande.

4.2.1.1 Liquid Limit

Liquid limit is the water corresponding to the arbitrary limit between liquid and

plastic state of consistency of soil. It is defined as the minimum water content at which the

soil is still in the liquid state, but as a small shearing strength against flowing, which can be

measured by standard available means. With reference to standard liquid limit device, it is

defined as the minimum water content at which a part of soil cut by a standard groove of

standard dimension will flow together for a distance of 12mm (1/2 inch) under an impact of

25 blows in a device.


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Fig 4.1Liquid Limit Test Apparatus

4.2.1.1.1 Determination of Liquid Limit

The liquid limit is that moisture content at which a soil changes from the liquid state

to the plastic state. It along with the plastic limit provides a means of soil classification as

well as being useful in determining other soil properties.

The change in behaviour from a plastic to a liquid state is a gradual one and so any

predefined boundary limit is bound to be arbitrary, depending as much on the equipment and

operator as upon the soil itself.

So with this in mind it was decided that an empirical technique should be used in

which the moisture content of a cohesive soil is varied and its shear strength indirectly

determined the moisture content at which the soil displays some shear strength is known as

the liquid limit.


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4.2.1.2 Plastic Limit

Plastic limit is the water content corresponding to an arbitrary limit between the

plastic and semi-solid state of a soil it is defined as the minimum water content at which a

soil will just begin to crumble when rolled into thread of approximately 3mm in diameter.

4.2.1.2.1 Plasticity Index

The range of consistency within which the soil exhibits plastic properties is known as

plastic range and is indicated by plasticity index. The plasticity index is defined as the

numerical difference between liquid limit and the plastic limit of the soil.

Plasticity index, = liquid limitplastic limit

In case of sandy soils, plastic limit should be determined first. When plastic limit cannot be

determined, the plasticity index is reported as NP (Non-Plastic) when plastic limit is equal to

or greater than liquid limit, the plasticity index is reported as zero.

The consistency of most soils in the ground will be plastic or semi-solid. Soil strength

and stiffness behaviour are related to the range of plastic consistency. The range of water

content over which a soil has a plastic consistency is termed as plasticity index.

In the BSCS fine soils are divided into ten classes based on their measured plasticity

index and liquid limit values: CLAYS are distinguished from SILTS, and five divisions of

plasticity are defined.


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Table 4.1 Divisions of Plasticity

Intermediate plasticity =35-50%

Low plasticity = 90

4.2.1.3 Shrinkage Limit

Shrinkage limit is the maximum water content at which a reduction in water content

will not cause decrease in volume of the soil. It is also the minimum moisture content to keep

a soil saturated without increasing the volume. This experiment gives an idea about shrinkage

or swelling which is likely to take place after being compacted as specified moisture content.

If a soil is compacted at its OMC which happens to be higher than its shrinkage limits (as in

heavy clays) the compacted soil mass will shrink on drying after compaction. If such clay is

compacted at about shrinkage limit (lower than OMC) it is likely to swell on soaking

subsequently.

4.2.2 Specific Gravity Test

Specific gravity is defined as the ratio of the weight of given volume of soil solids at a

given temperature to the weight of an equal volume of distilled water at that temperature,

both weights are taken in air.


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Fig 4.2Pycnometer

4.2.3 Sub-Grade Strength Evaluation

4.2.3.1 Modified Proctor Test

The extent of compaction depends on the moisture content of the soil and the comp

active effort used. In a compaction test the object is to determine the optimum moisture

content and maximum dry density achievable with a given compactive effort . A plot of dry

density versus moisture content indicates that compaction becomes more efficient up to a

certain moisture content, after which the efficiency decreases. The maximum dry density is

obtained at this optimum moisture content.


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4.2.3.2 California Bearing Ratio (CBR) Test

The method combines a load penetration test performed in the laboratory or in-situ

with the empirical design charts to determine the thickness of pavement and of its

constituents layers .This is probably the most widely used method for the design of flexible

pavement.


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Chapter 5

Results and Discussion

5.1 General

In this analysis various proportions of Blast Furnace Slag are taken. The test were

conducted to determine the various physical properties such as specific gravity, dry density,

moisture content, Atterbergs limits and California bearing ratio for different percentage of

Blast Furnace Slag. An attempt has been made to find out the suitability of Blast Furnace

Slag in the stabilization of road subgrade layer.

The test results are presented in this chapter are discussed with appropriate graphical

representation.

5.2 Physical Properties of soil

In the present investigation various physical properties such as Specific gravity,

Atterbergs limits such as plastic limit, shrinkage limit, plasticity index, toughness index,

California bearing ratio, optimum moisture content and dry density are calculated for

collected soil and is given in table 5.1


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Table 5.1 Properties of soil

Property Values

Liquid Limit (%) 45

Plasticity Index (%) 15.83

Flow Index (%) 22

Toughness Index (%) 71.91

Plastic Limit (%) 29.17

Specific Gravity 2.52

OMC (%) 26.415

Max Dry Density g/cc 1.725

Soaked CBR (%) 1.5


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5.3 Physical Properties of BFS

In this present investigation various physical properties of BFS such as Specific gravity,

optimum moisture content, dry density and CBR are represented in table 5.2

Table 5.2 Properties of BFS

Property Values


OMC (%) 9.3

5.4 Compaction Characteristics

Compaction properties i.e. maximum dry density (MDD) and optimum moisture content(OMC) were determined in the laboratory of all trial mixture in accordance with IS:

2720 (Part 8) - 1983. Variations of MDD and OMC of the mixes are shown in figs 5.8 and

5.9 respectively. From the figs 5.8 and 5.9, it is conferred that OMC increased and MDD

decreased with increasing percentage of BFS mixtures. The MDD increases by increasing

the content of BFS. The increase in OMC due to addition of BFS may be caused by the

absorption of water.


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Fig. 5.1Compaction Curve of 0% BFS


1.68

1.7

1.72

1.74

1.76

1.78

1.8

1.82

0 5 10 15 20 25 30 35

1.72

1.74

1.76

1.78

1.8

1.82

1.84

1.86

1.881.9

0 5 10 15 20 25 30


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1.7

1.75

1.8

1.85

1.9

1.95

2

0 5 10 15 20 25 30

1.82

1.84

1.86

1.88

1.9

1.92

1.94

1.961.98

2

2.02

0 5 10 15 20 25 30


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1.8

1.82

1.84

1.86

1.88

1.9

1.921.94

1.96

1.98

2

0 5 10 15 20 25 30

1.7

1.72

1.74

1.76

1.78

1.8

1.82

1.84

1.86

1.88

0 5 10 15 20 25 30


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Table 5.3 Compaction properties of different percentage of BFS

Blast Furnace slag

in %

OMC in % MDD in g/cc

0 18.2 1.81

5 19.5 1.89

10 21.93 1.96

15 22.3 2.01

20 23.8 1.98

25 24.7 1.86

30 26.19 1.83

1.55

1.6

1.65

1.7

1.75

1.8

1.85

0 5 10 15 20 25 30 35

MDD=1.83 g/cc

OMC=26.19%


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Fig. 5.8Variation of MDD with different % BFS

Fig. 5.9Variation of OMC with different % BFS

1.8

1.85

1.9

1.95

2

2.05

0 5 10 15 20 25 30 35

Drydensity(g/cc

)

BFS (%)

0

5

10

15

20

25

30

0 5 10 15 20 25 30 35

OMC

(%)

BFS %


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5.5 California Bearing Ratio

CBR test is one of the common tests for evaluating the strength of stabilized soils.

The soaked CBR tests were conducted on samples compacted at OMC, and soaked for 96

hours in accordance with IS: 2720 (Part 16) 1987. The variation in soaked CBR

value with addition of BFS mixtures is shown in fig 6. The soaked CBR of BFS mixture

increases with the increase in the BFS content. With addition of BFS, CBR value

increases and then decreases for 25 % BFS content

Fig. 5.10CBR Curve for 0% BFS

0

10

20

30

40

50

60

70

0 2 4 6 8 10 12 14


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0

10

20

30

40

50

60

0 2 4 6 8 10 12 14

0

10

20

30

40

50

60

0 2 4 6 8 10 12 14


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0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12 14

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14


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0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12 14

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12 14


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Table 5.4 CBR of different percentage of BFS

Blast Furnace slag

in %

CBR in %

0 1.5

5 1.86

10 2.51

15 3.18

20 4.35

25 3.42

30 2.75

Fig. 5.17Variation of CBR with different % of BFS

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 5 10 15 20 25 30 35

CBR%

BFS %


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5.6 Physical Properties of 20% slag and soil

Table 5.5 Properties of 20% slag and soil

Property Value


OMC (%) 23.8

Max Dry Density g/cc 1.98

CBR Soaked (%) 4.35


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FINAL RESULTS

Blast Furnace

Slag in %

OMC in % MDD in g/cc CBR in %

0 18.2 1.81 1.5

5 19.5 1.89 1.86

10 21.93 1.96 2.51

15 22.3 2.01 3.19

20 23.8 1.98 4.35

25 24.7 1.86 3.42

30 26.19 1.83 2.75


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Chapter 6

Conclusions

6.1 Conclusions

In our work we have made an attempt to utilize the waste material Blast Furnace Slag in

improving the strength charecteristics of road subgrade layer.

1. OMC increased and MDD decreased with the addition of BFS to the soil, MoreoverMDD increased with increase in BFS content.

2. The soaked CBR of BFS-soil mixture increases with the increase in the BFS content.3. By comparing the above results of CBR value, consistency limits, OMC and dry

density, we can conlude that 20% of soil can be replaced by Blast Furnace Slag.

Based on the result of this project ,it appears that soil can be effectively stabilized with the

addition of BFS. SoilBFS mixture are suitable for use in rural roads, embankment and it be

used as provide fill materials of comparable strength.


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Plate 3Conducting liquid limit test Plate 4Conducting liquid limit test

Plate 5 Conducting Specific gravity test Plate 6Conducting Specific gravity test


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Plate 7Soaked sample for CBR test

Plate 8Collection of BFS Slag Plate 10C.B.R Testing Machine


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References

[1]Yildirim, I. Z., and M. Prezzi, Publication FHWA/IN/JTRP-2009/32.

[2]Sanjay Kumar, Rakesh Kumar, Amitava Bandopadhyay, Title:Innovativemethodologies for the utilisation of wastes from industrial and allied industries

Resources, Conservation and Recycling 48 (2006) 301314

[3]Koteswara Rao. D et al. / International Journal of Engineering Science andTechnology (IJEST), Title: A laboratory study on the utilization of GBFS and Fly

Ash to stabilize the expansive soil for subgrade embankments, November 2011

[4]R. M. Nidzam; J. M. Kinuthia Sustainable soil stabilisation with blastfurnace slagSource:Proceedings of the ICE - Construction Materials, Volume 163, Issue 3, 01

August 2010, pages 157165, ISSN: 1747-650X, E-ISSN: 1747-6518

[5]Hongzhi Cui, T.Y. Lo, Feng Xing, Book title: 2nd International Symposium onService Life Design for Infrastructures,Title: The effect of slag on durability of

lightweight concrete, Publication year: 2010

[6]Zhulai Wang, Title: A research on ceramsite obtained from blast furnace slag andsewage sludge African Journal of Biotechnology Vol.10 (60), pp. 12934-12942, 5

October, 2011 ISSN 1684-5315 2011 Academic Journals
http://www.icevirtuallibrary.com/content/serial/coma;jsessionid=1s76gsipm0b79.z-telford-01http://www.icevirtuallibrary.com/content/issue/coma/163/3;jsessionid=1s76gsipm0b79.z-telford-01http://www.icevirtuallibrary.com/content/issue/coma/163/3;jsessionid=1s76gsipm0b79.z-telford-01http://www.icevirtuallibrary.com/content/serial/coma;jsessionid=1s76gsipm0b79.z-telford-01


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[7]Ch. Nageshwar Rao, Dept. of Civil Engineering, National Institute of TechnologyKarnataka, Mangalore, India. The 12th International Conference of International

Association for Computer Methods and Advances in Geomechanics (IACMAG) 1-6

October, 2008 Goa, India

[8]Wei-Hsing HuangThe Use of Bottom Ash in Highway Embankments, Subgrades, andSubbases. Publication FHWA/IN/JHRP-90/04. , Indiana Department of Transportation

and Purdue University, West Lafayette, Indiana, 1990. doi: 10.5703/1288284313434.

[9]IS: 2720-Part XVI(1987) Labotatory determination of CBR, Bureau of IndianStandard, New Delhi, India.


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Personal Profile

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A Study on Effect of Blast Furnace Slag in Road Subgrade Layer

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