study of soil properties with silica fume as stablizer and comparing the same with rbi-81 and cost...
DESCRIPTION
This involves replacing of base and sub-base course with stabilized locally available soil, and comparing same with different stabilizer (RBI-81and Silica Fume). To evaluate the difference in cost.TRANSCRIPT
VISVESVARAYA TECHNOLOGICAL UNIVERSITY
Belgaum-590 014
PROJECT REPORT
On
“STUDY OF SOIL PROPERTIES WITH SILICA FUME AS STABLIZER AND COMPARING THE SAME WITH RBI-81 AND COST ESTIMATION”
Submitted in partial fulfillment of the requirements for the Degree of
Post Graduate Diploma in Highway Technology
by
VENU GOPAL.N
USN: 1IR08CHT19
Under the Guidance of
Miss. G. KAVITHA
Lecturer,
RASTA – Center for Road Technology,
Bangalore.
RASTA – Center for Road Technology
VTU – Extension Center
VOLVO Construction Equipment Road Machinery Campus
1
Peenya, Bangalore – 560 058
RASTA – Center for Road Technology
VTU – Extension Center
VOLVO Construction Equipment Road Machinery Campus
Bangalore – 560 058.
CERTIFICATE
Certified that the Project work entitled “STUDY OF SOIL PROPERTIES
WITH SILICA FUME AS STABLIZER AND COMPARING THE
SAME WITH RBI-81 AND COST ESTIMATION” is a bonafied work carried
out by, Mr. VENU GOPAL.N, University Seat Number 1IR08CHT19 in partial fulfillment for the award of
M-Tech degree in Highway Technology of the Visvesvaraya Technological University, Belgaum during
the year 2008-2009. It is certified that all corrections/suggestions indicated for Internal Assessment have
been incorporated in the report. The Project report has been approved as it satisfies the academic
requirements in respect of Project work prescribed for the said Degree.
Signature of Guide Signature of Head of PG Studies
(Miss. G.Kavitha) (Dr. Krishnamurthy)
2
ACKNOWLEDGEMENT
It’s indeed my immense pleasure to wish my deep sense of gratitude to our teaching faculty
who inexorably tried to get the best out of me. It is because of their valuable guidance and continuous
encouragement without which this milestone would not have been a success.
I extend my sincere thanks to Dr.Krishna Murthy, for his valuable guidance and
suggestions during the course of study.
I would like to express my sincere gratitude to Miss. G.Kavitha and Mr. Anjaneyappa faculties of
IR Rasta for excellent guidance and encouragement throughout the seminar.
Last but not the least, I also thankful to all my class mates, non-teaching staff and friends, who
have helped directly or indirectly for the successful completion of this work.
3
SYNOPSIS
Soils exhibits high plasticity characteristics, low strength properties and high swell shrink
characteristics. The alternative swell- shrink seasons causes distress to the structures and the
pavements constructed on them. Maintenance and repair costs of the distressed structures and
pavements are quite high. It is, therefore, necessary either to bring suitable soils from far off
borrow areas or to stabilize locally available soils to improve their engineering properties.
In the present study, a soil sample was subjected to laboratory investigation to know the
grain size distribution pattern and to determine liquid limit, plastic limit and plasticity index,
optimum moisture content, maximum dry density and California bearing ratio values. The
laboratory investigations indicate the soil samples posses’ low strength. In order to improve the
strength of native soil, the soil samples were treated by varying Silica Fume and RBI-81 grade
content in the range of 1% to 4% by weight. The treated soil samples were subjected to triaxial
compression test to determine strength of soil.
The above obtained values such as CBR value, young’s Modulus etc were used for the
design of pavement based on IRC methods, thickness of pavement were calculated and
compared.
This involves replacing of base and sub-base course with stabilized locally available soil,
and comparing same with different stabilizer (RBI-81and Silica Fume). To evaluate the
difference in cost.
4
INDEX
Topics Page No
Chapter.1 Introduction 4-6
1.1 General Studies 4
1.2 Desirable properties of soil 5
1.3 Objective of present study 6
1.4 Scope of Present Study 6
Chapter.2 Literature review 7-20
2.1 General Studies 7
2.2 Characteristics of soil 7
2.3 Index properties 7
2.4 Determination of Soil Properties 9
2.5 Subgrade soil Strength 9
2.6 Soil Stabilization Using Inorganic stabilizer 11
2.7 Stabilized Soil with RBI-81 12
2.8 Silica Fume 15
2.9 Chemical Properties of silica fume 17
2.10 Physical properties and contribution 17
2.11 Soil Stabilization method 19
2.12 Technique of Stabilization 20
2.13 Design and Cost estimation 20
Chapter.3 Present Investigation 21-25
3.1 General Studies 22
3.2 laboratory test conducted 22
5
Chapter.4 Analysis of Result 26-43
4.1 General Studies 26
4.2 Laboratory test result 26
4.3 Design of Pavement 36
4.4 Materials Quantity 39
4.5 Cost Estimation 40
Chapter.5 Discussion and conclusion 44-45
5.1 Discussion 44
5.2 Conclusion 45
5.3 Scope for future studies 45
References 46
Annexure 1 47-57
6
CHAPTER-1
INTRODUCTION
1.1 GENERAL
Soil - mineral matter formed by the disintegration of rocks due to action of water, frost,
temperature, pressure or by plant or animal life. Soil is the most abundantly available construction
material; the term soil has different connotations for scientists belonging to different disciplines. The
definition given to a soil by an agriculturist or a geologist is different from the one used by a civil
engineer. For a civil engineer, soils mean all naturally occurring, relatively unconsolidated earth
material- organic or inorganic in character that lies above the bed rock. Soils can be broken down into
their constituent particles relatively easily, such as by agitation in water.
Soil is the ultimate foundation material which supports the overlying structure. The proper
functioning of the above lying structure will therefore depend critically on the success of the
foundation element. Soil is the cheapest and the most widely used material in a highway system,
either in its natural form or in a processed form. All road pavement structures eventually rest on
soil foundation. However, soil is highly heterogeneous and anisotropic in nature and occurs in
unlimited varieties, with widely different engineering properties. Considering all these aspects, a
through study of the engineering properties of soil is of vital importance in working out an
appropriate design of the pavement structure which will yield an acceptable level of performance
of the road over the design life under the given traffic and climatic conditions. In any road
embankment, the bulk of the material used is soil and if properly designed, should possess stable
slopes and should not settle to any appreciable extent. Also, the embankments require a stable
foundation; if the foundation soil happens to be soft clay, unless properly designed; excessive
settlement or even ultimate failure can take place.
In developing countries like India the biggest handicap to provide a complete net work of road
system is the limited finances available to build road by the conventional methods. Therefore there is a
7
need to resort to one of the suitable methods of low cost road construction to meet the growing needs of
the road traffic. The construction cost can be considerably decreased by selecting local materials
including local soils for the construction of the lower layers of the pavement such as the sub-base
course. If the stability of the local soil is not adequate for supporting wheel loads, the properties are
improved by soil stabilization techniques. Thus the principle of soil stabilized road construction
involves the effective utilization of local soils and other suitable stabilizing agents.
Earthwork as an important part of road construction
In any highway engineering work the construction of the embankment or the sub
grade is a very important activity. The earthwork constitutes 30% of the cost of the road
project. The pavement directly rests on the artificially prepared soil sub grade and thus
derives considerable strength from it. The adequate design and construction of
embankments is therefore the key to the successful performance of the roads.
1.2 Desirable properties of Sub grade soil
Stability
Incompressibility
Permanency of strength
Minimum changes in volume and stability under adverse condition
Good drainage
Ease of compaction
The soil should possess adequate stability or resistance to permanent
deformation under loads and should possess resistance to weathering thus
retaining the desired subgrade support. Minimum variation in volume will ensure
minimum variation in differential expansion and differential strength values. Good
drainage is essential to avoid excessive moisture retention and to reduce the
potential frost action. Ease of compaction ensures higher dry density and strength under
particular type and amount of compaction (1)
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1.3 Objective of present study
To characterize the soil under investigation based on its index properties.
To classify the soil as per IRC Classification.
To compare the OMC of the given soil & to achieve Maximum Dry density by
Proctor compaction tests.
To determine the strength of soil by Triaxial method.
To study the effect of RBI-81 and Silica Fume on soil by varying percentage.
To determine the strength enhancement of the given soil with stabilizer.
To determine the thickness by conventional method and Annexure method.
To compare the variation in cost by above method.
1.4 Scope of present study
The present study deals with the testing of soil properties of soil sample. The
following tests were done on the soil:
Grain size analysis
Atterberg limits
Compaction
California bearing ratio
Triaxial test
The soil is stabilized with a commercially available stabilizer called Road
Building International -81 (RBI-81) and the strength enhancement of the soil is
9
studied. And also compared with replacing RBI-81 with Silica fume, strength
enhancement is studied. Economically low cost design studies are done.
CHAPTER-2
LITERATURE REVIEW
2.1 General
Subgrade soil is an integral part of the road pavement structure as it provides the
support to the pavement from beneath. The main function of the subgrade is to give adequate
support to the pavement and for this the subgrade should posses’ sufficient stability under
adverse climatic and loading conditions .The formation of waves, corrugations, rutting and
shoving in black top pavements and the phenomenon of pumping, blowing and consequent
cracking of cement concrete pavements are generally attributed due to the poor subgrade
conditions.
When soil is used in embankment construction, in addition to stability
incompressibility is also important as differential settlement may cause failures. Compacted soil
and stabilized soil are often used in sub – base or base course of highway pavements. The soil is
therefore considered as one of the principle highway materials. (1)
2.2 Characteristics of soil
Soil consists mainly of mineral matter formed by the disintegration of rocks, by the
action of water, frost, temperature, pressure or by plant or animal life. Based on the individual
grain size of soil particles, soils have been classified as gravel, sand, silt and clay. The
characteristics of soil grains depend on the size, shape, surface texture, chemical composition
and electrical surface charges. Moisture and dry density influence the engineering behavior of a
soil mass. (1,2,3)
2.3 Index properties of soil
10
The wide range of soil types available as highway construction materials have made it
obligatory on the part of the highway engineer to identify and classify the different soils. The soil
properties on which their identification and classification are based on are known as index
properties. The index properties which are generally used are grain size distribution, liquid limit,
plastic limit and plasticity index. (1,2,3)
Grain size analysis
The grain size distribution is found by mechanical analysis. The components of soils
which are coarse grained may be analyzed by sieve analysis and the soil fines by sedimentation
analysis. The grain size analysis or the mechanical analysis is hence carried out to determine the
percentage of individual grain size present in a soil sample. (1,2,3)
Consistency limits and indices
The physical properties of fine grained soils, especially of clays differ very much at
different water contents. Clay may be almost in a liquid state, or it may show plastic behavior or
may be stiff depending on the moisture content. Plasticity is a property of outstanding
importance for clayey soils, which may be explained as ability to undergo changes of shape
without rupture. Atterberg in 1911 proposed a series of tests, mostly empirical, for the
determination of the consistency and plastic properties of fine soils. These are known as
Atterberg limits and indices.
Liquid limit may be defined as the minimum water content at which the soil will flow
under the application of very small shearing force. It is determined usually in the laboratory
using a mechanical device.
Plastic limit may be defined as the minimum moisture content at which the soil remains
in a plastic state. The lower limit is arbitrarily defined and determined in the laboratory by a
prescribed test procedure.
Plasticity index is defined as the numerical difference between the liquid and the plastic
limits. Plasticity index thus indicates the range of moisture content over which the soil is in
plastic condition.(1,2,3)
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2.4 Determination of soil properties
There are various tests that are carried out to determine the various properties of the soil
1. Liquid limit: The water content at which the soil has a small shear that it flows to close a
groove of standard width when jarred in a specified manner.
2. Plastic limit: The plastic limit is the water content at which the soil to crumble when rolled
into threads of specified size.
3. Plasticity index: The amount of water which must be added to change a soil from its
plastic limit to its liquid limit is an indication of the plasticity of the soil. The plasticity is
measured by the “plasticity index” which is equal to the liquid limit minus the plastic limit.(5)
4. Grain size analysis: It is also known as mechanical analysis of soils is the determination of
the percentage of individual grain sizes present in the sample. The results of the test are of
great value in soil classification. There are two methods of sieve analysis :
(i) wet sieving applicable to all soils and
(ii) Dry sieving applicable to soils having negligible proportion
of clay and silt. (3)
5. Compaction test: This test is carried out to find out the optimum moisture content and the
maximum dry density of the given soil(2,3).
2.5 Sub-grade soil strength
The factors on which the strength characteristics of soil depend are:
(i) Soil type
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(ii) Moisture content
(iii) Dry density
(iv) Internal structure of the soil and
(v) The type and mode of stress application (1).
2.5.1 Evaluation of soil strength
The tests used to evaluate the strength properties of soils may be broadly divided into
three groups:
(i) Shear test
(ii) Bearing test and
(iii) Penetration test.
The following tests were carried out in the present study to find the strength of the soil
1. CBR test: This test was developed by the Californian Division of highways as a method of
classifying and evaluating soil sub-grade and base course materials for flexible pavement. The
CBR is a measure of resistance of a material to penetration of standard plunger under
controlled density and moisture conditions.
2. Triaxial compression test: This test is carried to evaluate the in-situ strength of the soil
sample under controlled loading.(2,3,)
Table: Density requirement of embankment and subgrade
Type of work Maximum laboratory dry unit weight when
tested as per IS:2720(part 8)
Embankments up to 3 meters
Height, not subjected to expensive flooding.Not less than 15.2kN/cu.m.
Embankments exceeding 3 meters height or
embankments of any height subject to long
periods of inundation
Not less than 16.0kN/cu.m.
13
Subgrade and earthen Shoulders/ verges/
backfill Not less than 17.5kN/cu.m.
2.6 Soil stabilization using powder based inorganic stabilizer
The effectiveness of this stabilizer both plastic & non-plastic soils is studied by carrying
out a detailed laboratory study. Different types of soils that is gravelly, sandy, silty, clayey are
stabilized with inorganic stabilizer in the range of 2-12%. Apart from the study of geotechnical
properties of individual soils, strength in terms of UU & CBR of stabilized soils was evaluated.
The selected soils viz. gravelly, sandy & silty are observed to be non-plastic. Clayey soil
is observed to be highly compressible in nature.
The Triaxial strength of all the soils increases with the addition of stabilizer content for
different curing periods. The rate of increase is more in silty & gravelly soils as compared
to sandy & clayey soils.
The CBR value increases with stabilizer content for all soils. It is observed that the value
increases significantly after addition of 2% content. The rate of increase is more in
gravelly & silty soils as compared to sandy & clayey soils.
Gravelly soil with 6% & silty soil with 4% stabilizer content may be used as a sub-base
layer of pavement. Gravelly & silty soils with 8% stabilizer content may be used as a
base layer of pavement.
All the soils stabilized with 2% stabilizer content may be used for shoulder construction.
It can be concluded that powder based inorganic stabilizer has the potential for
stabilization of gravelly & silty soils to make it suitable for its use in improved sub
base/base layer/shoulder construction of a road pavement. Solution to a typical practical
problem indicated substantial reduction in the total pavement thickness which not only
reduces the total cost but also avoids the use of natural depleting conventional materials.
Test tracks of suitable length may be constructed & monitored over a period of time
before adopting such specifications for large scale field applications.
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2.7 Stabilized road
If the stability of the local soil is not adequate for supporting the wheel loads, the
properties are improved by soil-stabilization techniques. Thus the principle of soil stabilized road
construction involves the effective utilization of local soils and other suitable stabilizing agents.
The term soil stabilization means the improvement of the stability or bearing power of
the soil by the use of controlled compaction, proportioning and or the addition of suitable
admixture or stabilizers. Soil stabilization deals with physical physico-chemical and chemical
methods to make the stabilized soil serve its purpose as a pavement component material. (1,4)
2.7.1 Advantages of stabilization
(i) It improves the engineering properties of poor soils as well as enhancing that of good
soils to meet the specified requirements.
(ii) It helps reduce the need of existing borrow pit materials and prospecting of new
borrow pit sources there by protecting environment.
(iii) It eliminates the need for the landfill sites for dumping of poor materials and
environmental harmful materials as well as construction waste
(iv) It allows faster construction because removal of substandard material and
transportation of good materials is not required.
(v) Time saved also adds to cost saving of the project and allows more projects to be
undertaken and complete within the same time frame.
2.7.2 Properties of stabilization
Bonds soil particles together (increases strength & stiffness).
Reduces permeability (fills voids, forms membrane).
Improves compaction (lubrication, particle restructuring).
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2.7.3 Features & Benefits
Higher resistance (R) values
Reduction in plasticity
Lower permeability
Reduction of pavement thickness
Elimination of excavation, material hauling and handling, and base importation
Aids compaction
Provides "all-weather” access onto and within project sites.
The principles are:
Evaluating the properties of given soil
Deciding the method of supplementing the lacking property by the effective and economical
method of stabilization.
Designing the stabilized soil mix for intended stability and durability values.
RBI Grade 81 soil stabilizer is an advanced technological development with economic and
environmental benefits. It is a unique, environmentally friendly, comprehensive and irreversible
inorganic stabilizer for road construction. The technology was developed by scientists incorporating
natural materials with well proven efficacy and durability. It has undergone a rigorous development and
verification process internationally coordinated by Road Building International and has been granted an
international patent. Road Building International has engineered an inorganic product:
is extremely effective
whose action is irreversible
is produced from natural ingredients
is capable of providing rapid infrastructure development progress while preserving the
environment by using the in-situ natural soil.
Avoids the environmental burdens associated with conventional road construction.
16
RBI Grade 81 can be effectively applied to all soil types:
• In-situ application with RBI Grade 81 causes no interruption to traffic.
• Resultant cost savings of 60% (in comparison to conventional methods).
• RBI Grade 81 avoids the otherwise necessary removal and dumping of asphalt (5).
2.7.4 Properties of RBI-81 stabilizer
Table 2.1: properties of RBI-81 stabilizer(5)
CHEMICAL COMPOSITION
POWDER
Properties % by mass
Ca CaO- 52-56
Si SiO215-19
S SO3 9-11
Al Al2O3 5-7
Fe Fe2O3 0-2
Mg MgO 0-1
Mn, K, Cu, Zn Mn+K+Cu+Zn 0,1-0,3
H2o 1-3
Fibers (polypropylene) 0-1
Additives 0-4
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2.8 Silica fume
2.8.1 Definition for silica fume
The American Concrete Institute (ACI) defines silica fume as “very fine non-
Crystalline silica produced in electric arc furnaces as a by-product of the production of elemental
silicon or alloys containing silicon” (ACI 116R). It is usually a gray colored powder, somewhat
similar to Portland cement or some fly ashes(6,7).
2.8.2 Pozzolanic — will not gain strength when mixed with water. Examples include silica
fume meeting the requirements of ASTM C 1240, Standard Specification for Silica Fume Used
in Cementitious Mixtures, and low-calcium fly ash meeting the requirements of ASTM C 618,
Standard Specification for Coal Ash and Raw or Calcined Natural Pozzolanic for Use in
Concrete, Class F.
2.8.3 Cementitious — will gain strength when mixed with water. Examples include ground
granulated blast-furnace slag meeting the requirements of ASTMC989, Standard Specification
for Ground Granulated Blast-Furnace Slag for use Concrete and Mortars, or high-calcium fly
ash meeting the requirements of ASTM C 618, Class C.
2.8.4 Production
Silica fume is a by-product of producing silicon metal or ferrosilicon alloys in
smelters using electric arc furnaces. These metals are used in many industrial applications to
include aluminum and steel production, computer chip fabrication, and production of silicones,
which are widely used in lubricants and sealants. While these are very valuable materials, the by-
product silica fume is of more importance to the concrete industry(7).
18
Fig shows production of Silica
Fig 1.2 EMISSION OF SILICA FUME
Figure 1.2 shows a smelter in the days before silica fume was being captured for use in concrete
and other applications. The “smoke” leaving the plant is actually silica fume. Today in the
United States, no silica fume is allowed to escape to the atmosphere. The silica fume is collected
in very large filters in the bag house and then made available for use in concrete
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2.9 Chemical Properties
Amorphous. This term simply means that silica fume is not a crystalline material. A
crystalline material will not dissolve in concrete, which must occur before the material can react.
Don’t forget that there is a crystalline material in concrete that is chemically similar to silica
fume. That material is sand. While sand is essentially silicon dioxide (SiO2), it does not react
because of its crystalline nature.
Trace elements. There may be additional materials in the silica fume based upon the metal
being produced in the smelter from which the fume was recovered. Usually, these materials have
no impact on the performance of silica fume in concrete.
2.10 Physical Properties
Particle size. Silica fume particles are extremely small, with more than 95%
of the particles being less than 1 µm (one micrometer). Particle size is extremely important for
both the physical and chemical contributions (discussed below) of silica fume in concrete.
Bulk density. This is just another term for unit weight. The bulk density of the as-
produced fume depends upon the metal being made in the furnace and upon how the furnace is
operated. Because the bulk density of the as-produced silica fume is usually very low, it is not
very economical to transport it for long distances.
Specific gravity. Specific gravity is a relative number that tells how silica fume compares
to water, which has a specific gravity of 1.00. Silica fume has a specific gravity of about 2.2,
which is somewhat lighter than portland cement, which has a specific gravity of 3.15.
20
PHYSICAL PORPERTIES OF SILICA FUME(7)
Specific surface.
Specific surface is the total surface area of a given mass of a material. Because the particles
of silica fume are very small, the surface area is very large. We know that water demand
increases for sand as the particles become smaller; the same happens for silica fume. This fact is
why it is necessary to use silica fume in combination with a water-reducing admixture or a super
plasticizer. A specialized test called the “BET method” or “nitrogen adsorption method” must be
used to measure the specific surface of silica fume. Specific surface determinations based on
sieve analysis or air-permeability testing are meaningless for silica fume.
Figure 2.1
21
Figure2.1. Photomicrograph of Portland cement grains (left) and silica-fume particles (right) at
the same magnification. The longer white bar in the silica fume side is 1 micrometer long. Note
that ACI 234R, Guide for the Use of Silica Fume in Concrete, estimates that for a 15 percent
silica-fume replacement of cement, there are approximately 2,000,000 particles of silica fume for
each grain of Portland cement.
Chemical contributions
Because of its very high amorphous silicon dioxide content, silica fume is a very reactive
pozzolanic material in concrete. As the Portland cement in concrete begins to react chemically, it
releases calcium hydroxide. The silica fume reacts with this calcium hydroxide to form
additional binder material called calcium silicate hydrate, which is very similar to the calcium
silicate hydrate formed from the portland cement.
Physical contributions
Adding silica fume brings millions and millions of very small particles to a concrete
mixture. Just like fine aggregate fills in the spaces between coarse aggregate particles, silica
fume fills in the spaces between cement grains. This phenomenon is frequently referred to as
particle packing or micro-filling. Even if silica fume did not react chemically, the micro-filler
effect would bring about significant improvements in the nature of the concrete. Below table
present a comparison of the size of silica-fume particles to other concrete ingredients to help
understand how small these particles actually are.
2.11 Soil stabilization methods
The methods of soil stabilization which are in common use are:
(i) Chemical Stabilization
(ii) Mechanical stabilization(1)
2.11.1 Effects of stabilization
Soil stabilization may result in any one or more of the following changes:
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1. Increase in stability, change in properties like density or swelling, change in
physical characteristics.
2. Change in chemical properties.
3. Retaining and desired strength by water proofing(1)
2.12 Techniques of soil stabilization
Based on the above principles, the various technique of soil stabilization may be grouped
Proportioning technique
1. Cementing agents
2. Modifying agents
3. Water proofing agents
4. Water repelling agents
5. Water retaining agents
6. Heat treatment
7. Chemical stabilization
8. In all the above methods, adequate compaction of the stabilized layers is the most
essential requirement. (1)
2.13 Design and cost estimation.
As per IRC-37 the conventional methods was used to calculate the thickness of different
layer, which was further compared with IRC-37 Annexure method difference in thickness is
calculated. (8)
The cost which are involved for materials were taken from Schedule Rate (SR), and
calculated. (9)
CHAPTER-3
PRESENT INVESTIGATION
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3.1 General Studies:
Soil is one of the principle materials of construction in soil embankments and in
stabilized soil base and sub-base courses.
Various types of soil have various properties at different stretch of the sub grade.
Thus, it is important to carry out basic soil tests at a stretch of 300mts.
In view of the wide diversity in soil type, it is desirable to classify the subgrade soil
into groups possessing similar physical properties.
In the present investigation the soil is classified on the basis of simple laboratory
tests such as grain size analysis and consistency limit tests.
Soil compaction is an important phenomenon in highway construction as compacted
subgrade improves the load supporting ability of the pavement; in turn resulting in pavement
thickness requirement. Compaction of earth embankments would result in decreased
settlement. Thus the behavior of soil subgrade material could be considerably improved by
adequate compaction under controlled conditions. The laboratory compaction tests are
conducted and the optimum moisture content at which the soil should be compacted and the
dry density that should be achieved at the construction site has been determined.
Soil for the present study was obtained from the project site. The basic tests like
Atterberg limits, compaction test, California bearing resistance & Triaxial test was done to
characterize the soil based on its properties.
The representative soils were stabilized using the stabilizers Road Building
International-81 and Silica Fume for different proportions i.e. 1%, 2% and 4% stabilizer to
assess their properties and the results were analyzed. Road Building International has
engineered as an inorganic product:
• Is capable of providing rapid infrastructure development progress while preserving
the environment by using the in-situ natural soil.
24
• Avoids the environmental burdens associated with conventional road construction. In
the present study, soil was subjected to basic tests like:
• Grain size analysis
• Atterberg limits
• Compaction
• California bearing ratio test
• Triaxial test (at 0.7, 1.4 and 2.1 kg/sqcm confinement)
3.2 Laboratory test conducted on soil: (2,3)
3.2.1 Grain size analysis:
The percentage of various sizes of particle in a given dry soil sample is determined by
grain size analysis. Grain size analysis also knows as mechanical analysis of soils is the
determination of the percent of individual grain sizes present in the sample.
Fig 1: Indian standard grain size soil classification system
25
Fig-3.1 Sieve Analysis Apparatus
3.2.2 Atterberg limits:
By consistency is meant the relative ease with which soil can be deformed. This
term is mostly used for fine grained soils for which the consistency is related to a large
extent to water content. Consistency denotes degree of firmness of the soil which may be
termed as soft, firm, stiff or hard. In 1911 Atterberg divided the entire range from liquid to
solid state into four stages liquid state, plastic state, semi -solid state and solid state. He
set arbitrary limits known as consistency limits or Atterberg limits, for these divisions in
terms of water content. Thus the consistency limits are the water contents at which the soil
mass passes from one state to the next.
Liquid limit (WI): It is defined as the minimum water content at which the soil is
still in the liquid state, but has a small shearing strength against flowing which can be
measured by standard available means. With reference to the standard liquid limit device,
it is defined as the minimum water content at which a part of soil cut by a groove
of standard dimensions will flow together for a distance of 12mm under an impact of 25
26
blows in the device.
Plastic limit (WP): plastic limit is the water content corresponding to an arbitrary limit
between the plastic and the semi-solid states of consistency of a soil. It is defined as the
minimum water content at which a soil will just begin to crumble when rolled
into a thread approximately 3mm in dia.
3.2.3 Compaction test:
Compaction of soil is a process by which the soil particles are constrained to be packed
more closely together by reducing the air voids. It causes decrease in air voids and consequently
increases in dry density. This may result in increase in shearing strength. Degree of compaction
is usually measured quantitatively by dry density.
Compaction refers to a more or less rapid reduction mainly in the air voids under a loading of
short duration Increase in dry density of soil due to compaction mainly depends on two factors.
Compacting moisture content
The amount of compaction.
3.2.4 California bearing ratio test (CBR):
The CBR is a measure of resistance of a material to penetration of standard
plunger under controlled density and moisture conditions. CBR test is mainly utilized for
the design of pavement structure. The test is simple and has been extensively
investigated for field correlations of flexible pavement thickness requirement.
The test consists of causing a cylindrical plunger of 50mm diameter to penetrate a
pavement component material a 1.25mm/min. The load for 2.5mm and 5mm are
recorded. This load is expressed as a percentage of standard load value at a
respective deformation level to obtain CBR value.
27
Fig-3.2 CBR mould preparation Fig 3.3- CBR Testing Machine
3.2.5 Triaxial compression test:
The triaxial compression test in which the test specimen is compressed by
applying all the three principal stress. The cell pressure in the triaxial cell is also called
the confining pressure.
Fig-3.4 Triaxial testing machine Fig-4.5 Mould Extractor
28
CHAPTER-4
ANALYSIS OF RESULTS
4.1 General
The laboratory tests for the various properties of the soil were conducted and the results thus obtained are tabulated and analyzed.
The test was conducted on locally available soil and the properties were compared with
and without the use of stabilizer.
4.2 Laboratory tests on soil material
4.2.1 Wet sieve analysis
Sample Calculation:
Sample: Native Red Soil
Wt of sample taken: 500gms
Table 4.1 shows the sample calculation
sample Red Soil
sieve size
Wt of sample reained
cumulative Wt retained cum % wt ret %fine passing
4.75 122.17 122.17 24.434 75.566
2.36 24.44 146.61 29.322 70.678
1.18 41.22 187.83 37.566 62.434
0.6 40.65 228.48 45.696 54.304
0.425 29.94 258.42 51.684 48.316
0.15 36 294.42 58.884 41.116
0.075 9.59 304.01 60.802 39.198
Gravel Sand Fines24.434 24.434 24.434
29
0
10
20
30
40
50
60
70
80
Seive size
Graph of wet sieve analysis
Type of soil as per IS-Classification: Sandy Clayey (SC) Soil
4.2.2 Atterberg limit: Native Red Soil
Table 4.2 shows the liquid limit calculation
30
Cu=23.54
Cc=3.1
No of blows M/C %10 45.9413 44.0824 42.5829 41.72
Table 4.2.1 shows Plastic limit
M/C container No 123 75 52 21Wt of container gms (W1) 23.86 21.98 27.18 40.47Wt of cont + wit soil (W2) 26.03 23.58 29.15 42.34Wt of cont + dry soil % (W3) 25.54 23.23 28.71 41.92
M/c % 29.17 28.00 28.76 28.97 28.72
Remarks
LL "from graph" 42.4PL 28.72PI 13.68
Liquid limit and Plastic Index table
soil Native(RS) RS+1% RBI RS+2% RBI RS+4% RBI RS+1% SF RS+2% SF RS+4% SF
LL 42.4 42 41.61 40.01 40 39.57 38.6
PL 28.72 28.74 28.76 27.92 26.97 27.51 26.93
PI 13.68 13.24 12.87 12.09 13.03 12.06 11.63
0 0.5 1 1.5 2 2.5 3 3.5 4 4.510.5
11
11.5
12
12.5
13
13.5
14
RBI-81% SF
% dosage
PI
31
4.2.3 Compaction test
Sample Calculation:
Sample: Red Soil
Type of Compaction : Modified Proctor
Type of Soil : New
Type of Mould : Small
Type of Hammer : 4.89
No. of Layers : 5
No. of Blows : 25
Table 4.2.2 shows the sample calculation
Moisture Content (%) Bulk Density (g/cc) Dry Density (g/cc)9.07 1.90 1.74
11.33 1.96 1.7612.91 2.11 1.8614.73 2.12 1.8516.41 2.08 1.79
8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.001.65
1.70
1.75
1.80
1.85
1.90
M/C (%)
Dry D
ensit
y(gm
/cc)
32
OMC=13.54%
MDD=1.877gm/cc
Remarks: MDD and OMC for different % are of RBI-81 & Silica Fume.
Type of Stabilizer Native(RS) RBI-81 Silica fumepercentage 0% 1% 2% 4% 1% 2% 4%Compaction
OMC (%) 13.54 13.48 13.52 13.89 12.34 13.16 13.1MDD (gm/cc) 1.877 1.882 1.887 1.869 1.887 1.893 1.94
4.2.4 California bearing ratio test
Sample Calculation:
Sample: Red Soil
Area of plunger = 19.64cm2
CBR = 8% (This has been assumed as per Guidelines) (1), the value is on lower side.
4.2.5 Triaxial Compression Test:
Sample Calculation: Red soil
Specimen details:
Diameter: 3.8cm
Height: 7.6cm
Volume, V = (πd2/4) * h
= (π*3.82/4) * 7.6
V = 86.19 cm3
Mass = volume * density
= 86.19 * 1.87
= 167.48gms
Water = 13.54% * 161.78
= 20.07gms
33
RBI Silica Fume
1.0% = 1.62 gms 1.63gms
2.0% = 3.52 gms 3.26gms
4.0% = 6.44 gms 6.69gms
The above calculated mass of soil, water and RBI according to varying percentages are mixed together and put into the mould, mould is extracted and placed for moist curing for 3days.
Table 4.2.5 sample calculation at different confining pressure says 0.7, 1.4 and 2.1kg/cm2.
Native Red soil cm mm pressure(σ 31) kg/cm2 2.1
length of specimen 7.6 76 Load at Failure (kg)
Dia of specimen 3.8 38 least count (dial gauge), mm 0.001
area of specimen(Ai) 11.34 1133.90 least count ( proving ring), mm 0.002
dial gauge
∆ (mm)
proving
load(kg) Strain()
Corrected area
Ac=(Ai/(1-)cm2
Stress (kg/cm2)
noted taken readings
0 0.00 0 0 0 0.00E+00 11.339 0.00 10 0.01 3 3 0.66 1.32E-04 11.338 0.06 20 0.02 4 4 0.88 2.63E-04 11.336 0.08 30 0.03 1 5 1.1 3.95E-04 11.335 0.10 40 0.04 1.2 7 1.54 5.26E-04 11.333 0.14 50 0.05 1.2 7 1.54 6.58E-04 11.332 0.14 60 0.06 2.2 12 2.64 7.89E-04 11.330 0.23 70 0.07 4.3 23 5.06 9.21E-04 11.329 0.45 80 0.08 9.2 47 10.34 1.05E-03 11.327 0.91 90 0.09 13.1 66 14.52 1.18E-03 11.326 1.28
100 0.10 17.4 89 19.58 1.32E-03 11.324 1.73 110 0.11 1+2.3 113 24.86 1.45E-03 11.323 2.20 120 0.12 8.1 141 31.02 1.58E-03 11.321 2.74 130 0.13 12.3 163 35.86 1.71E-03 11.320 3.17 140 0.14 17.2 187 41.14 1.84E-03 11.318 3.63 150 0.15 2+2.3 213 46.86 1.97E-03 11.317 4.14 160 0.16 7.4 239 52.58 2.11E-03 11.315 4.65 170 0.17 12.1 261 57.42 2.24E-03 11.314 5.08 180 0.18 18.2 292 64.24 2.37E-03 11.312 5.68 190 0.19 3+3.4 319 70.18 2.50E-03 11.311 6.20
34
200 0.20 9 345 75.9 2.63E-03 11.309 6.71 210 0.21 14.4 374 82.28 2.76E-03 11.308 7.28 220 0.22 4+.2 402 88.44 2.89E-03 11.306 7.81 230 0.23 -0.1 401 94.6 3.03E-03 11.305 7.80 240 0.24 .4 398 99.88 3.16E-03 11.303 7.78 250 0.25 1.3 394 100.76 3.29E-03 11.302 7.73 260 0.26 1.4 391 111.32 3.42E-03 11.300 7.64
Table 4.2.6 Shear Strength obtained for Native soil (RS)
σ 31(Kg/cm2)ShearStrength
(kg/cm2)%Dosage
0.7 0.21301.4 0.287
2.1 0.311
Annexure 1: Shows Triaxial compression test Graphs with different %dosage at 0.7, 1.4 and
2.1kg/sqcm confinement pressure.
35
Deviator stress (σd=F/Ac)
1.294
Normal Stress (σ 11)kg/cm2
3.394
Table 4.2.7 Abstract of Triaxial Test Result.
Sample Native Soil
sl noload area'Ac' Stress (Kg/cm) Atterberg limits E3 value
Kg Sqcm σ 31 σ d σ 11 LL PI Kg/sqcm Mpa1 4.93 11.267 0.7 0.962 1.662 42.04 13.68 2430 238.302 5.87 11.284 1.4 1.001 2.401 42.04 13.68 2580 253.013 7.81 11.28 2.1 1.293 3.393 42.04 13.68 2751 269.78
SampleNative Soil + 1%
RBI81
sl noload area'Ac' Stress (Kg/cm) Atterberg limits E3 value
Kg Sqcm σ 31 σ d σ 11 LL PI Kg/sqcm Mpa1 7.59 11.289 0.7 0.437 1.137 42 13.24 3500 343.232 10.35 11.312 1.4 0.519 1.919 42 13.24 3622 355.203 11.33 11.29 2.1 0.692 2.792 42 13.24 3667.67 359.68
SampleNative Soil + 2%
RBI81
sl noload Area 'Ac' Stress (Kg/cm) Atterberg limits E3 value
Kg Sqcm σ 31 σ d σ 11 LL PI Kg/sqcm Mpa1 10.84 11.303 0.7 0.672 1.372 41.61 12.87 3600 353.042 11.29 11.283 1.4 0.917 2.317 41.61 12.87 3681 360.983 14.59 11.278 2.1 1.005 3.105 41.61 12.87 4000 392.27
SampleNative Soil + 4%
RBI81
sl noload Area 'Ac' Stress (Kg/cm) Atterberg limits E3 value
Kg Sqcm σ 31 σ d σ 11 LL PI Kg/sqcm Mpa1 14.58 11.29 0.7 1.291 1.991 40.01 12.09 3733 366.082 15.47 11.293 1.4 1.370 2.770 40.01 12.09 4090 401.093 20.58 11.278 2.1 1.825 3.925 40.01 12.09 4600 451.11
Sample Native Soil + 1%Silica
36
Fume
sl noload Area 'Ac' Stress (Kg/cm) Atterberg limits E3 value
Kg Sqcm σ 31 σ d σ 11 LL PIKg/sqcm Mpa
1 8.86 11.284 0.7 1.021 1.721 40.00 12.96 3689 361.772 11.55 11.259 1.4 1.133 2.533 40.00 12.96 3846 377.173 12.61 11.275 2.1 1.701 3.801 40.00 12.96 4000 392.27
SampleNative Soil + 2%Silica
Fume
sl noload Area 'Ac' Stress (Kg/cm) Atterberg limits E3 value
Kg Sqcm σ 31 σ d σ 11 LL PIKg/sqcm Mpa
1 11.52 11.281 0.7 0.785 1.485 39.47 12.04 3816 374.222 12.76 11.294 1.4 1.023 2.423 39.47 12.04 4000 392.273 19.18 11.287 2.1 1.117 3.217 39.47 12.04 4966 487.00
SampleNative Soil + 4%Silica
Fume
sl noload Area 'Ac' Stress (Kg/cm) Atterberg limits E3 value
Kg Sqcm σ 31 σ d σ 11 LL PIKg/sqcm Mpa
1 14.37 11.284 0.7 1.273 1.973 38.60 11.62 4333.3 424.952 21.44 11.275 1.4 1.902 3.302 38.60 11.62 5000 490.343 23.7 11.25 2.1 2.107 4.207 38.60 11.62 5125 502.59
37
Table 4.2.8 sample calculation at different confining pressure says 0.7, 1.4 and 2.1kg/cm2.
Sl No.
Type of soil
Days Confinement pressure (kg/cm 2 )
E3 in kg/cm 2
0% 1% 2% 4%
1) Native Soil(RS)
3 0.7 2430 - - -
1.4 2580 - - -
2.1 2751 - - -
1) RS + % RBI-81
3 0.7 - 3500 3600 3743
1.4 - 3622 3681 4090
2.1 - 3733 4090 4600
3) RS +% Silica Fume
3 0.7 - 3689 3816 4333
1.4 - 3846 4000 5000
2.1 - 4333 4966 5125
Table 4.2.10 Test result for %Dosage for 1.4 kg/cm2 confinements
Atterberg limits
LoadShear parameter E3 value
Soil + % Stabilizer
LL PI Kg σ 31
(Kg/cm2)
σ d
(Kg/cm2)
Shear strength(Kg/cm2)
Kg/cm2 Mpa
Native (RS) 42.04 13.68 5.87 1.4 0.519 0.287 2580253.0
1
RS+1% RBI-81 42 13.24 10.35 1.4 0.917 0.361 3622355.2
0
RS+2% RBI-81 41.61 12.87 11.29 1.4 1.001 0.507 3681360.9
8
RS+4% RBI-81 40.01 12.09 15.47 1.4 1.370 0.674 4090401.0
9
RS +1% SF 40 13.03 11.35 1.4 1.023 0.417 3846377.1
7RS +2% SF 39.57 12.06 12.76 1.4 1.133 0.571 4000 392.2
38
7
RS +4% SF 38.6 11.63 21.44 1.4 1.903 0.922 5000490.3
4
Table 4.2.11 Shear Strength obtained for Native soil (RS) with % Dosage
σ 31(Kg/cm2)
Shear Strength kg/cm2
Red soil (RS)
RS+1% RBI-81
RS+2% RBI-81
RS+4% RBI-81
RS+1% SF
RS+2% SF
RS+4% SF
0.7 0.213 0.308 0.434 0.557 0.337 0.534 0.811
1.4 0.287 0.361 0.507 0.674 0.417 0.571 0.922
2.1 0.311 0.422 0.581 0.791 0.454 0.652 1.032
4.3. Design of pavement:
Method 1: By IRC-37 CBR method,
Enter the Values For Design of Flexible Pavement as per ‘IRC37 Guidelines’
CBR value (%)8
Length of road 40 km
Type of Road 4 Lane Dual carriage way
Design life 'n' 10IRC 37 Guidelines
Growth factor 'r'0.07
VDF value 'F'4.5
Lane distribution factor 'D'0.75
Initial traffic in the year of completion (CVPD) 'A'
5000
Cumulative num of standard axle 'N' 85.101 msa
39
N= (365*((1+r) n -1)*A*D*F)/r
A=P (1+r) x
Table shows Thickness obtained for different layers by CBR method,
As per CBR method obtained thickness (mm) 630
Indivial layer thickness unit mt cm mm
BM0.04 4 40
DBM0.14 14 140
Base0.25 25 250
Sub-Base0.2 20 200
total0.63 63 630
Method 2: By IRC-37 Annexure1 method,
Moduls of Elasticity of Subgrade, Sub-base and Base layers
Step1 Input the data
Elastic Modulus of Subgrade 'E3' (Mpa)254.5686
Thickness of Granular Layer 'h' (mm) / H2 450
Composite Elastic Modulus of granular Sub-Base and base 'E2' (Mpa)E2=E3*0.2*h0.45
795.76Step2
Elastic Modulus of RBI81 'E1' (Mpa)505.68375
Thickness of Granular Layer H2 (mm)450
Changed thickness using stabilizer 'H1' (mm) 565
40
((E1 (H1)3)/ 12(1-µ12))= ((E2 (H2)3)/12(1-µ2
2))
From the above formula we calculate ‘H1’, µ is the Poisson’s ratio.
Table 4.2.12 shows the thickness variation with different %Dosage
soil Native(RS)RS+1% RBI RS+2% RBI
RS+4% RBI RS+1% SF RS+2% SF
RS+4% SF
composite Elastic modulus of Granular Sub Base and Bas Layer(mm) E2Kg/cm2 - 8114 8114 8114 8114 8114 8114
Mpa - 795.76 795.76 795.76 795.76 795.76 795.76Thickness reqd - 588 584 564 576 568 528rounded thickness
-590 585 565
575 570 530
chip carpet - 20 20 2020 20 20
Total thickness - 610 605 585595 590 550
Table 4.2.13 shows the thickness variation by different layers
soil + % RBI Native RS
RS+1 % RBI
RS+2 % RBI RS+4 % RBI
RS+1 % SF RS+2 % SF RS+4 % SFThickness (mm)
BC 40 - -- - - -- -
DBM 140 - - - - - -
chip carpet - 20 20 20 20 20 20
BASE (WMM) 250590 585 565 575 570 530
SUBBASE (GSB) 200
total Thickness 630 610 605 585 595 590 550
41
4.4. Materials Quantity
Considering 4-lane dual carriage way with 4mt wide median and 2mt paved shoulder on either side.
Table 4.2.13 materials required per km stretch.
Materials required per Km in cum (as per IRC-37 CBR method)
Native soil thickness (mm) Qty (cum)BC 880
DBM 3080BASE (WMM) 5500
SUBBASE (GSB) 4400
Table 4.2.14 materials required per km stretch.
Soil + % Stabilizer
material Required per Km
BM DBM Chip carpet Base Sub-BaseB&SB
ReplacedStabilizer
Required(m3)
Unitm3 m3 m2 m3 m3 m3 RBI-81
Silica Fume
RS+1% RBI-81 - - 22000 - 12980 130 -RS+2% RBI-81 - - 22000 - - 12870 257 -RS+4% RBI-81 - - 22000 - - 12430 497 -
RS +1% SF - - 22000 - - 12650 - 127RS +2% SF - - 22000 - - 12540 - 251RS +4% SF - - 22000 - - 11660 - 466
42
4.5. Cost analysis,Cost are estimated based on scheduled rates and are noted6.
Table 4.2.15 Cost involved per m3
Cost per m3 (in Rs.) as per SR PWD
BM DBM Base Sub-Base Chip carpet B&SB Replaced
Stabilizer per m3
m3 m3 m3 m3 m2 m3 RBI-81 Silica Fume
6000 5500 1400 1100 280 350 37 5
Table 4.2.16 Cost involved per km of stretch as per CBR method design
Materials required(cum) and cost involved per Km as per IRC-37 CBR method
native soil qty rate per cum Amount(Rs.)BC 880 6500 57,20,000.00DBM 3080 5500 1,69,40,000.00BASE (WMM) 5500 1450 79,75,000.00SUBBASE (GSB) 4400 1100 48,40,000.00
Total cost(Rs). 3,54,75,000.00
43
Table 4.2.17 Cost involved per km of stretch as per IRC-37 Annexure1 method.
Material required per Km and cost estimated as per IRC-37 annexure method
qtyrate(Rs.
) amount(Rs.)
qtyrate(Rs.
) amount(Rs.)RBI 1% SF 1%
Chip carpet( sqm) 22000 285
62,70,000.00
Chip carpet sqm 22000 285
62,70,000.00
RBI in kgs11700
0 36 42,12,000.00 SF in kgs
190500 6
11,43,000.00
soil in cum 12980 350 45,43,000.00 soil in cum 12980 350
45,43,000.00
Total Cost
1,50,25,000.00 Total Cost
1,19,56,000.00
qtyrate(Rs.
) amount(Rs.)
qtyrate(Rs.
) amount(Rs.)RBI 2% SF 2%
Chip carpet( sqm) 22000 285
62,70,000
Chip carpet sqm 22000 285
62,70,000.00
RBI in kgs23130
0 36 83,26,800 SF in kgs
376500 6
22,59,000.00
soil in cum 12870 350 45,04,500 soil in cum 12870 350
45,04,500.00
Total Cost 1,91,01,300 Total Cost
1,30,33,500.00
qtyrate(Rs.
) amount(Rs.)
qtyrate(Rs.
) amount(Rs.)RBI 4% SF 4%
Chip carpet( sqm) 22000 285
62,70,000
Chip carpet sqm 22000 285
62,70,000.00
RBI in kgs44730
0 36 1,61,02,800 SF in kgs
684000 6
41,04,000.00
soil in cum 12430 350 43,50,500 soil in cum 12430 350
43,50,500.00
Total Cost Total Cost
44
2,67,23,300 1,47,24,500.00
Table 4.2.18 Abstract of Modulus of sub grade, plastic index, thickness and cost with % relationship at 1.4kg/sqcm confinement pressure.
soil + % RBI
Native RS RS+1 % RBI
RS+2 % RBI
RS+4 % RBI
RS+1 % SF RS+2 % SF RS+4 % SF
Dosage (%)
0 1 2 4 1 2 4
PI 13.68 13.24 12.87 12.09 13.03 12.06 11.63Total thickness (mm)
630 610 605 585 595 590 550
total cost(Rs.)
3,54,75,000
1,50,25,000
1,91,01,300
2,67,23,300
1,19,56,000
1,30,33,500
1,47,24,500
Modulus of Sub-grade E3 (@ 1.4kg/sqcm confinement pressure)
Kg/cm2 2580 3622 3681 4090 3846 4000 5000Mpa 253.01 355.2 360.98 451.11 377.17 392.27 490.34
% Decreas
e in thicknes
s 0 3.17 3.97 7.14 5.56 6.35 12.70%
Savings 0 57.65 46.16 24.67 66.30 63.26 58.49%
increase in E3 value 0.00 40.39 42.67 58.53 49.07 55.04 93.80
45
0 0.5 1 1.5 2 2.5 3 3.5 4 4.50
2
4
6
8
10
12
14
% Dosage
% D
ecr
ease
in
th
ickn
ess
RBI-
81
SF
The above graph1 shows % decrease in Thickness verses % Dosage of stabilizer
0 0.5 1 1.5 2 2.5 3 3.5 4 4.50.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
% Dosage
% in
cre
ase
in E
3
SF
RBI-
81
The above graph2 shows % increase in modulus value verses % Dosage of stabilizer
46
0 0.5 1 1.5 2 2.5 3 3.5 4 4.50
10
20
30
40
50
60
70
% Dosage
% S
avin
gs
SF
RBI-81
The above graph3 shows % Savings in cost verses % Dosage of stabilizer
CHAPTER-5
DISCUSSION AND CONCLUSION
5.1 Discussion
The study of soil characteristics and the analysis is very important aspect in the design of
the pavement which involves several complexities due to variable factors. This study is aimed at
evaluating the strength properties of the given soils by stabilization using the given stabilizers
and the results are compared.
Plastic index was reduced when % Stabilizer dosage increased. But % decrease was
greater when Silica Fume was used.
Shear strength was also increased when specimen was subjected to Triaxial test with
different confinement pressure with different dosage. But the specimen with 4% RBI-81
showed shear failure at a confinement pressure of 0.7kg/cm2. But with same % of Silica
47
fume as stabilizer, bulging was observed .So from above point of view infra that with
increase in RBI dosage the stabilized layer shows rigid behavior.
Young’s modulus of stabilized soil also increased with increase in % stabilizer dosage to
about 60% and 90% with RBI-81 and Silica Fume as stabilizer.
All the above observations are based on 3days moist curing.
Design of pavement as per IRC-37 based on CBR showed required thickness of
630mm(BC=40mm,DBM=140mm,Base=250mm,Sub-Base=200mm), and cost involved
was around 3.6cr for 4-lane dual carriage way with 4mt median and 2mt paved shoulder
on either side, as per scheduled rate for materials.
When design was compared with IRC-37 Annexure method the thickness of pavement
was reduced by replacing all the layers with stabilized locally available soil, here the
Modulus of elasticity was taken at confining pressure of 1.4kg/sqcm.
From above design with different stabilizer shows that, when the Silica Fume as
stabilizer with 4% dosage at confining pressure of 1.4kg/ sqcm the thickness was
reduced by around49% with bulging . Similarly when RBI-81 as stabilizer the thickness
was reduced around 28% with shear failure.
Comparing with the cost estimated it showed around 46% and 62% savings with RBI-81
and Silica Fume as stabilizer with 2% dosage.
5.2 Conclusion
The conclusion given below are based on 3 days moist curing and testing for Sandy
clayey(SC) type of soil which was classified based on IS-Classification. And rates as
per scheduled rate6.
The above results when compared shows Silica Fume can be used as stabilizer.
When Silica fume as stabilizer comparing with RBI-81 with 2 and 4%dosage
shows around 15 and 30 % savings compared with conventional method design.
48
As test are need to be carried out for more soil samples and allowing for moist
curing for more number of days and observing the failure characteristic which
type stabilizer to use can be suggested .
As the above design method i.e. (IRC-37 Annexure) pavement thickness
obtained need be studied with trial stretch, observations are need to be made.
5.3 Scope for future studies
Since Silica fume is a byproduct it may be harmful for environment, using such
materials for construction in different forms at different level may reduce the harmful
effect in future.
Since Silica Fume as Cementitious property it can be used in highway construction.
Studies have be carried out for different types of pavement with waste materials like
Silica Fume, as stabilizer or partially replacing cement in rigid pavement or with
silica fume alone.
References
1. Highway Engineering by S.K.Khanna and C.E.G. Justo.
2. Highway materials and pavement testing by S.K.Khanna - C.E.G. Justo-
A.Veeraragavan.
3. Geotechnical Engineering by T.N.Ramamurthy and T.G. Sitharam.
4. Highway Engineering by Dr.L.R.Kadyali and Dr.N.B.Lal.
5. http://www.icjonline.com/views/2002_07_Singh.pdf ,
http://greenbuildings.santa-monica.org/appendices/apamaterials.html
6. www.chronicindia.org suppliers in Silica Fumes.
7. Civil Engineering Materials by Handoo, Mahajan Kaila.
8. IRC-37 Guidelines for design of flexible pavements by Indian Road
Congress
49
Annexure 1
Shows Triaxial compression test (Stress verses Strain) Graphs with different %dosage at 0.7, 1.4
and 2.1kg/sqcm confinement pressure.
1. Triaxial test result Graphs for Native Red Soil (RS) at 0.7kg/sqcm confinement pressure.
50
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-03 7.00E-03 8.00E-030.00
2.00
4.00
6.00
8.00
10.00
12.00
Strain
Shea
r st
ress
(kg/
cm2)
E=2430 Kg/sqcm
2. Triaxial test result Graphs for Native Red Soil (RS) at 1.4 kg/sqcm confinement pressure.
51
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-03 7.00E-030.00
2.00
4.00
6.00
8.00
10.00
12.00St
ress
E=2580.64 Kg/sqcm
3. Triaxial test result Graphs for RS +1% RBI-81 at 0.7 kg/sqcm confinement pressure.
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-030.00
1.00
2.00
3.00
4.00
5.00
6.00
Strain
Shea
r Str
ess(
kg/s
qcm
)
E=3500 Kg/ sq cm
4. Triaxial test result Graphs for RS +1% RBI-81 at 1.4 kg/sqcm confinement pressure.
52
0.00E+00 5.00E-04 1.00E-03 1.50E-03 2.00E-03 2.50E-03 3.00E-03 3.50E-030.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
Strain
She
ar s
tre
ss (
kg/s
qcn
)
E=3622Kg/sqcm
5. Triaxial test result Graphs for RS +1% RBI-81 at 2.1 kg/sqcm confinement pressure.
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-030.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
E=3689.17 Kg/sqcm
6. Triaxial test result Graphs for RS +2% RBI-81 at 0.7 kg/sqcm confinement pressure.
53
0.00E+00 5.00E-04 1.00E-03 1.50E-03 2.00E-03 2.50E-03 3.00E-03 3.50E-03 4.00E-03 4.50E-030.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
Strain
Shea
r St
ress
(Kg/
sqcm
)
E=3600 Kg/sqcm
7. Triaxial test result Graphs for RS +2% RBI-81 at 1.4 kg/sqcm confinement pressure.
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-030.00
2.00
4.00
6.00
8.00
10.00
12.00
Strain
Shea
r St
ress
(kg/
sqcm
)
E=3681.12 Kg/sqcm
8. Triaxial test result Graphs for RS +2% RBI-81 at 2.1 kg/sqcm confinement pressure.
54
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-03 7.00E-030.00
2.00
4.00
6.00
8.00
10.00
12.00
Strain
She
ar s
tre
ss(K
g/sq
cm)
E=4090.32 Kg/sqcm
9. Triaxial test result Graphs for RS +4% RBI-81 at 0.7 kg/sqcm confinement pressure.
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-030.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
Strain
Shea
r St
ress
(kg/
sqcm
)
E=3733.33 Kg/sqcm
10. Triaxial test result Graphs for RS +4% RBI-81 at 1.4 kg/sqcm confinement pressure.
55
0.00E+00
5.00E-04
1.00E-03
1.50E-03
2.00E-03
2.50E-03
3.00E-03
3.50E-03
4.00E-03
4.50E-03
5.00E-03
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
Strain
Shea
r St
ress
(Kg/
sqcm
)
11. Triaxial test result Graphs for RS +4% RBI-81 at 2.1 kg/sqcm confinement pressure.
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-03 7.00E-030.00
5.00
10.00
15.00
20.00
25.00
Strain
Shea
r St
ress
(kg/
sqcm
)
E=4600.90 Kg/sqcm
12. Triaxial test result Graphs for RS +1% SF at 0.7 kg/sqcm confinement pressure.
56
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-030.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
Strain
Shea
r St
ress
(Kg/
sqcm
)
E=3689.46 Kg/cm2
13. Triaxial test result Graphs for RS +1% SF at 1.4 kg/sqcm confinement pressure.
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-03 7.00E-03 8.00E-03 9.00E-030.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
E=3846.67Kg/cm2
14. Triaxial test result Graphs for RS +1% SF at 2.1 kg/sqcm confinement pressure.
57
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-03 7.00E-030.00
5.00
10.00
15.00
20.00
25.00
Strain
Shea
r St
ress
(kg/
sqcm
)
E=4000.87Kg/cm2
15. Triaxial test result Graphs for RS +2% SF at 0.7 kg/sqcm confinement pressure.
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-03 7.00E-030.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
Strain
Shea
r Str
ess(
Kg/s
qcm
)
E=3816.81Kg/sqcm
16. Triaxial test result Graphs for RS +2% SF at 1.4 kg/sqcm confinement pressure.
58
-5.00E-04
9.97E-18
5.00E-04
1.00E-03
1.50E-03
2.00E-03
2.50E-03
3.00E-03
3.50E-03
4.00E-03
4.50E-03
5.00E-03
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
Strain
Shea
r st
ress
(kg/
sqcm
)
E=4000 Kg/sqcm
17. Triaxial test result Graphs for RS +2% SF at 2.1 kg/sqcm confinement pressure.
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-030.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
Strain
Shea
r St
ress
(kg/
sqcm
)
E=4966.57 Kg/sqcm
18. Triaxial test result Graphs for RS +4% SF at 0.7 kg/sqcm confinement pressure.
59
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-030.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
Strain
Shea
r St
ress
(Kg/
sqcm
)
E=4333.33 Kg/sqcm
19. Triaxial test result Graphs for RS +4% SF at 1.4 kg/sqcm confinement pressure.
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-03 7.00E-030.00
5.00
10.00
15.00
20.00
25.00
Strain
Shea
r str
ess(
kg/s
qcm
)
E=5000 Kg/sqcm
20. Triaxial test result Graphs for RS +4% SF at 2.1 kg/sqcm confinement pressure.
60
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03 6.00E-03 7.00E-03 8.00E-03 9.00E-030.00
5.00
10.00
15.00
20.00
25.00
Strain
Shea
r Str
ess(
kg/s
qcm
)
E=5125.18 Kg/ sqcm
61