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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
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A MINOR PROJECT
ON
COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT
FORSTABILIZED AND UNSTABILIZED SOIL
Submi tted to
SANGHAVI INSTITUTE OF MANAGEMENT & SCIENCE,INDORE
Institute of Technology and Management
Rajiv Gandhi ProudyogikivVishwavidhyalayaBhopal (M.P.)
2014-2015
In The Partial fulfillment of Bachelor Degree in Civil Engineering
Guided by: Submitted to: Submitted by:
Er. Yogesh Sharma H O D CIVIL ParmanandPatidar
BE VII Sem( Civil)Roll No: 0837CE111070
RAJIV GANDHI PROUDYOGIKI VISHWAVIDHYALAYA,BHOPAL, (MP)
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SIMS,INDORE (2011-2015)
CERTIFICATE
This is to certify that the minor project entitled, COMPARATIVE STUDY
BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
UNSTABILIZED SOIL Submitted by Mr.ParmanandPatidarinpartial
fulfillment of the requirements for the award of bachelor of engineering degree in
civil engineering under the subject minor civil engineering project at the
RAJIV GANDHI PROUDYOGIKI VISHWAVIDYALAYA, BHOPAL.
The work has been examined by us and recommended for acceptance.
EXTERNAL EXAMINER INTERNAL EXAMINER
DATE: DATE:
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ACKNOWLEDGMENT
It is always a pleasure to remind the fine people in the Engineering Work u come
to know for their sincere guidance I received to uphold my practical as well as
theoretical skills in engineering.
Mostly we would like to thank ER. Yogesh Sharma (Guide) for extending their
friendship towards us and making a pleasure-working environment on the field and
lab. A paper is not enough for me to express the support and guidance we received
from them almost for all the work we did there. They were a great help not only on
how work take place on field but also told some life learning experience they were
blessed with.
Secondly we would like to thank Prof. R P Pandey (HOD of Civil Engineering ) for
giving opportunity for doing minor project.
Thirdly we would like to thank ER. PushpendraSoni (Minor project co-ordinator)
for the positive attitude he showed for our work, always allowing us to question
him and giving prompt replies for our uncertainties in all the fields including
educational, and managerial to practical work.
Finally we apologize all other unnamed who helped us in various ways to have a
good project.
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ABSTRACT
India is an emerging economy and second faster growing country of the world and
a developing country, Infrastructure is a key factor in the growth of each country,
Infect it is a indicator that indicate how much a country is growing and at which
rate.
Transportation and road network is a major sector in the infrastructure. India
a huge agricultural land and 65% of the population of country lives in rural areas,
therefore it is very necessary to connect rural and urban areas for the socio
economic growth of country.
The village is only connected with fair weather road. If the said villages are
connected with BT road by the approach road, the villages around the way will be
economically benefited. The Villagers are mainly dependent on the agriculture and
for proper transport and getting proper price of their produces, all weather road is
necessary, A part from this, villagers will also get the facilities of good education
and health. Therefore, to ensure socio-economic transforming breaking the
isolation of village communities, elimination of disparity between rural and urban
population and bringing about urban rural integration.
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CONTENT
Page No.
CHAPTER-1 INTRODUCTION 9
1.1General 9
1.2Pavement 10
1.3Purpose Of Pavement 11
1.4Selection Of Type Of Pavement 12
1.5Selection Criteria 13
1.6Factors For Comparing Flexible & Rigid Pavement 14-50
1.7Considerations for Flexible vs. Rigid Pavements 51
1.8 Soil Stabilization 52-53
CHAPTER-2 EXPERIMENTAL PROGRAMME 54
2.1Properties Of Soil 55-56
2.2Particle Size Distribution (sieve analysis) 56-58
2.3CBR Test 59-60
CHAPTER-3 RESULTS 61-66
CHAPTER-4 CONCLUSION 67-68
REFERENCE 69
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LIST OF FIGURES
Fig. 1 Typical Cross Section Of Flexible Pavement 14
Fig. 2 . Layers Of Flexible Pavement 17
Fig. 3 Typical Rigid Pavement 18Fig. 4 Layers Of Rigid Pavement 19
Fig. 5 PCC Surface 20
Fig. 6 Rigid Pavement Slab 21
Fig. 7 Rigid Pavement Showing Contraction Joints 23
Fig. 8 Skewed Contraction Joint 24
Fig. 9 Construction Joint 25
Fig.10 Longitudinal and Transverse Construction Joints 26
Fig.11 Stainless Steel-Clad Dowel Bars 27
Fig.12 Dowel Bars in Place at a Construction Joint 27
Fig.13 CBR Curve For Flexible pavement Design 29
Fig14 Thickness of crust required for different traffic 31
Fig15 Thickness of crust required for different traffic 32
Fig.16 Thickness of crust required for different traffic 34
Fig.17 Flexible Pavement Load Distribution 43
Fig.18 Rigid Pavement Load Distribution 45
Fig.19 Stress Distribution In Flexible And Rigid 46
Fig.20 Stress Distribution In Flexible And Rigid 47
Fig 21 Pavements Stress Overlap Due to Dual Wheel 47
Fig.22 Critical Line of Equal Costs (Swing Line) 50
Fig.23 Variation of CBR w.r.t % of lime 65
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LIST OF TABLES
Table 1 Cost of Flexible Pavements in Million Rupees for 48
Different Combinations of Soil and Traffic
Table 2 Cost of Rigid Pavements in Million Rupees for 49
Different Combinations of Soil and Traffic
Table 3 Stabilization methods for pavements (from rolling, 1996). 53
Table 4 Observation of coarse sieving 57
Table 5 Observation of fine sieving 58
Table 6 Physical properties of various soils 62
Table 7 Liquid limit (L.L.), plastic limit (P.L.), plasticity index (P.I.) 62
at different percentage of lime.
Table 8 variation of thickness of pavement for unstabilized soil 66
Table 9 variation of thickness of pavement for stabilized soil 66
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CHAPTER 1
INTRODUCTION
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INTRODUCTION
1.1 GeneralThe two most important factors that govern pavement design are soil sub-grade strength and
traffic loading. Depending on the strength of sub-grade soil, the layer thicknesses of flexible as
well as rigid pavements are affected. IRC:37-20015 uses soil sub-grade strength in terms of CBR
in flexible pavement; whereas IRC: 58 - 20026 uses the same in terms of modulus of sub-grade
reaction (k) for rigid pavement. The traffic load is generally estimated from 3-day axle load
survey. In the design of flexible pavements, traffic load is expressed in terms of million standard
axles (msa); whereas it is expressed in terms of axle load distribution (ALD) in design of rigid
pavements.
The present study was undertaken in two parts. In the first part, mathematical models are
developed to obtain the ALD on a highway from its vehicle volume count. The ability to convert
the soil sub-grade strength given in terms of CBR into modulus of subgrade reaction (k), and a
traffic load given in terms of msa into ALD makes it possible to design the two types of
pavements for the same soil and traffic conditions expressed differently. In the second part,
flexible and rigid pavements are designed for similar soil and traffic conditions and their costs
are compared.
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1.2 PAVEMENT
A pavement is usually a combination of several layers placed on top of an existing subgrade
(usually soil) so that vehicle loads from traffic can be transmitted safely to the subgrade without
failure or excessive damage (i.e., deformation, strain, cracking, rutting, etc.) that may affect the
serviceability of the road during the design lifespan of the pavement.
The two most important factors that govern pavement design are soil sub-grade strength and
traffic loading. Depending on the strength of sub-grade soil, the layer thicknesses of flexible as
well as rigid pavements are affected.
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1.3 PURPOSE OF PAVEMENT
Typically, pavements are built for three main purposes:
Load support:
Pavement material is generally stiffer than the material upon which it is placed, thus it assists the
in situ material in resisting loads without excessive deformation or cracking.
Smoothness:
Pavement material can be placed and maintained much smoother than in situ material. This helps
improve ride comfort and reduce vehicle operating costs.
Drainage:
Pavement material and geometric design can effect quick and efficient drainage thus eliminating
moisture problems such as mud and ponding (puddles).
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1.4 SELECTION OF TYPE OF PAVEMENT
The types of pavement generally considered for new construction and rehabilitation in California
are rigid, flexible and composite pavements. Rigid pavement should be considered as a potential
alternative for all Interstate and other high traffic volume interregional freeways. Flexiblepavement should be considered as a potential alternative for all other State highway facilities.
Composite pavement, which consists of a flexible layer over a rigid pavement have mostly been
used for maintenance and rehabilitation of rigid pavements on State highway facilities.
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1.5 Selection Criteria
Because physical conditions and other factors considered in selecting pavement type vary
significantly from location to location, the Project Engineer must evaluate each project
individually to determine the most appropriate and cost-effective pavement type to be used. Theevaluation should be based on good engineering judgment utilizing the best information
available during the planning and design phases of the project together with a systematic
consideration of the following project specific conditions:
Pavement design life
Traffic considerations
Soils characteristics
Weather (climate zones)
Existing pavement type and conditionAvailability of materials
Recycling
Maintainability
Constructibility
Cost comparisons (initial and life-cycle)
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1.6 FACTORS FOR COMPARING FLEXIBLE ANDRIGID PAVEMENT
1.6.1 BASIC ELEMENTS OF PAVEMENT
Flexible Pavement :-
A flexible pavement structure is typically composed of several layers of material
with better quality materials on top where the intensity of stress from traffic loads is high and
lower quality materials at the bottom where the stress intensity is low. Flexible pavements can be
analyzed as a multilayer system under loading.
A typical flexible pavement structure consists of the surface course and underlying
base and sub-base courses. Each of these layers contributes to structural support and drainage.
When hot mix asphalt (HMA) is used as surface course, it is the stiffest (as measured by resilient
modulus) and underlying layers are less stiff but are still important to pavement strength as well
as drainage and frost protection
Fig. 1 Typical Cross Section Of Flexible Pavement
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The Subgrade
It is the natural in situ material. The top 500 mm of subgrade should be compacted to the
desirable density near the optimum moisture content. This compacted subgrade may be the in-
situ soil or a layer of selected material.
The Base Course
The base course is the layer of materialimmediately beneath the surface or binder course. It can
be composed of crushed stone, crushed slag, or other untreated or stabilized materials.
Sub-base Course
The sub-base course is the layer of material beneath the base course. The reason that two
different granular materials are used is for economy. Instead of using the more expensive base
course material for the entire layer, local and cheaper materials can be used as a sub-base course
on top of the subgrade. If the base course is opening graded, the sub-base course with more fines
can serve as a filter between the subgrade and the base course. Sometimes the base course could
be cemented (in rigid pavement).
Prime Coat
Itis an application of low-viscosity cutback asphalt to an absorbent surface, such as an untreated
granular base on which an asphalt layer will be placed. Its purpose is to bind the granular base to
the asphalt layer.
Tack Coat
It is a very light application of asphalt, usually asphalt emulsion diluted with water, used to
ensure a bond between the surface being paved and the overlying course. It is important that each
layer in an asphalt pavement be bonded to the layer below. Tack coats are also used to bond the
asphalt layer to a PCC base or an old asphalt pavement. The three essential requirements of a
tack coat are that it must be very thin; uniformly cover the entire surface to be paved is allowed
to cure before the HMA is laid.
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The Seal Coat
It is a thin bituminous layer used to waterproof the surface or to provide skid resistance where
the aggregates in the surface course could be polished by traffic and become slippery.
Asphalt/Bitumen
Asphaltic bitumen is obtained by refining the petroleum crude. It is the costliest and a very
important component of the bituminous mix. The applicability and adhesive properties of
bitumen along with the proper proportioning with stone aggregates is the basic requirement to
make workable layer mixes.
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Layers of construction: section of 2 lanes
Fig.2 Layers Of Flexible Pavement
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Rigid Pavement:-
Rigid pavement structure is composed of a hydraulic cement concrete surface course and
underlying base and sub base courses (if used). Another term commonly used is Portland cement
concrete (PCC) pavement, although with today's pozzolanic additives, cements may no longer be
technically classified as "Portland".
The surface course (concrete slab) is the stiffest layer and provides the majority of strength. The
base or sub-base layers are orders of magnitude less stiff than the PCC surface but still make
important contributions to pavement drainage and frost protection and provide a working
platform for constructions equipment.
Rigid pavements are substantially 'stiffer' than flexible pavements due to the high
modulus of elasticity of the PCC material, resulting in very low deflection under loading. The
rigid pavements can be analyzed by the plate theory. Rigid pavements can have reinforcing steel,
which is generally used to handle thermal stresses to reduce or eliminate joints and maintain tight
crack width. Figure shows typical section for a rigid pavement.
Fig. 3 Typical Rigid Pavement
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Layers of constructions
Fig. 4 Layers Of Rigid Pavement
A typical rigid pavement structure (see Figure 3) consists of the surface course and the
underlying base and subbase courses (if used). The surface course (made of PCC) is the stiffest
(as measured by resilient modulus) and provides the majority of strength. The underlying layers
are orders of magnitude less stiff but still make important contributions to pavement strength as
well as drainage and frost protection.
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Surface Course
The surface course is the layer in contact with traffic loads and is made of PCC. It provides
characteristics such as friction (see Figure 2.3),smoothness, noise control and drainage. In
addition, it serves as a waterproofing layer to the underlying base, subbase and subgrade. The
surface course can vary in thickness but is usually between 150 mm (6 inches) (for light loading)
and 300 mm (12 inches) (for heavy loads and high traffic). Figure 2.4 shows a 300 mm (12 inch)
surface course.
Figure 5 PCC Surface
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Figure 6 Rigid Pavement Slab
(Surface Course) Thickness
The base course is immediately beneath the surface course. It provides (1) additional load
distribution, (2) contributes to drainage and frost resistance, (3) uniform support to the pavement
and (4) a stable platform for construction equipment. Bases also help prevent subgrade soil
movement due to slab pumping. Base courses are usually constructed out of:
1. Aggregate base. A simple base course of crushed aggregate has been a common
option since the early 1900s and is still appropriate in many situations today.
2. Stabilized aggregate orStabilizing agents are used to bind otherwise loose particles to
one another, providing strength and cohesion. Cement treated bases (CTBs) can be
built to as much as 20 - 25 percent of the surface course strength (FHWA, 1999).
However, cement treated bases (CTBs) used in the 1950s and early 1960s had a
tendency to lose excessive amounts of material leading to panel cracking and settling.
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3. Dense-graded HMA. In situations where high base stiffness is desired base courses
can be constructed using a dense-graded HMA layer.
4. Permeable HMA. In certain situations where high base stiffness and excellent
drainage is desired, base courses can be constructed using an open graded HMA.
Sub base Course
The sub base course is the portion of the pavement structure between the base course and the
subgrade. It functions primarily as structural support but it can also:
1. Minimize the intrusion of fines from the subgrade into the pavement structure.
2.
Improve drainage.
3. Minimize frost action damage.
4. Provide a working platform for construction.
The sub base generally consists of lower quality materials than the base course but better than the
subgrade soils. Appropriate materials are aggregate and high quality structural fill. A sub base
course is not always needed or used.
Joints
Joints are purposefully placed discontinuities in a rigid pavement surface course. The most
common types of pavement joints, defined by their function ,are : contraction, expansion,
isolation and construction.
(a) Contraction Joints
A contraction joint is a sawed, formed, or tooled groove in a concrete slab that creates aweakened vertical plane. It regulates the location of the cracking caused by dimensional changes
in the slab. Unregulated cracks can grow and result in an unacceptably rough surface as well as
water infiltration into the base, subbase and subgrade, which can enable other types of pavement
distress. Contraction joints are the most common type of joint in concrete pavements, thus the
generic term "joint" generally refers to a contraction joint.
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Contraction joints are chiefly defined by their spacing and their method of load transfer. They are
generally between 1/4 - 1/3 the depth of the slab and typically spaced every 3.1 - 15 m (12 - 50
ft.) with thinner slabs having shorter spacing (see Figure 2.25). Some states use a semi-random
joint spacing pattern to minimize their resonant effect on vehicles. These patterns typically use a
repeating sequence of joint spacing (for example: 2.7 m (9 ft.) then 3.0 m (10 ft.) then 4.3 m (14
ft.) then 4.0 m (13 ft.)). Transverse contraction joints can be cut at right angles to the direction of
traffic flow or at an angle (called a "skewed joint"). Skewed joints are cut at obtuse angles to the
direction of traffic flow to help with load transfer. If the joint is properly skewed, the left wheel
of each axle will cross onto the leave slab first and only one wheel will cross the joint at a time,
which results in lower load transfer stresses.
Figure 7 Rigid Pavement Showing Contraction Joints
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Figure 8 Skewed Contraction Joint
(The Tinning is Perpendicular to the Direction of Travel While the Contraction Joint is skewed)
(b) Expansion Joints
An expansion joint is placed at a specific location to allow the pavement to expand without
damaging adjacent structures or the pavement itself. Up until the 1950s, it was common practice
in the U.S. to use plain, jointed slabs with both contraction and expansion joints (Sutherland,
1956). However, expansion joint are not typically used today because their progressive closure
tends to cause contraction joints to progressively open (Sutherland, 1956). Progressive or even
large seasonal contraction joint openings cause a loss of load transfer particularly so for joints
without dowel bars.
(c) Isolation Joints
An isolation joint is used to lessen compressive stresses that develop at T- and unsymmetrical
intersections, ramps, bridges, building foundations, drainage inlets, manholes, and anywhere
differential movement between the pavement and a structure (or another existing pavement) may
take place (ACPA, 2001). They are typically filled with a joint filler material to prevent water
and dirt infiltration.
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(d) Construction Joints
A construction joint (see Figure 2.7) is a joint between slabs that results when concrete is placed
at different times. This type of joint can be further broken down into transverse and longitudinal
construction joints (see Figure 2.31). Longitudinal construction joints also allow slab warping
without appreciable separation or cracking of the slabs.
Workers manually insert dowel bars into the construction joint at the end of the work day.
Construction joints should be planned so that they coincide with contraction joint spacing toeliminate extra joints.
Figure 9 - Construction Joint
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Figure 10 - Longitudinal and Transverse Construction Joints
Dowel Bars
Dowel bars are short steel bars that provide a mechanical connection between slabs without
restricting horizontal joint movement. They increase load transfer efficiency by allowing the
leave slab to assume some of the load before the load is actually over it. This reduces jointdeflection and stress in the approach and leave slabs.
Dowel bars are typically 32 to 38 mm (1.25 to 1.5 inches) in diameter, 460 mm (18 inches) long
and spaced 305 mm (12 inches) apart. Specific locations and numbers vary by state, however a
typical arrangement might look like Figure 2.34. In order to prevent corrosion, dowel bars are
either coated with stainless steel (see Figure 2.9) or epoxy (see Figure 2.36). Dowel bars are
usually inserted at mid-slab depth and coated with a bond-breaking substance to prevent bonding
to the PCC. Thus, the dowels help transfer load but allow adjacent slabs to expand and contract
independent of one another. Figure 2.10 shows typical dowel bar locations at a transverse
construction joint.
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Figure 11 - Stainless Steel-Clad Dowel Bars
Figure 12 -Dowel Bars in Place at a Construction Joint
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Tie Bars
Tie bars are either deformed steel bars or connectors used to hold the faces of abutting slabs in
contact Although they may provide some minimal amount of load transfer, they are not designed
to act as load transfer devices and should not be used as such Tie bars are typically used at
longitudinal joints or between an edge joint and a curb or shoulder. Typically, tie bars are about
12.5 mm (0.5 inches) in diameter and between 0.6 and 1.0 m (24 and 40 inches long).
Reinforcing Steel
Reinforcing steel can also be used to provide load transfer. When reinforcing steel is used,
transverse contraction joints are often omitted Therefore, since there are no joints, the PCC
cracks on its own and the reinforcing steel provides load transfer across these cracks. Unlikedowel bars, reinforcing steel is bonded to the PCC on either side of the crack in order to hold the
crack tightly together.
Typically, rigid pavement reinforcing steel consists of grade 60 (yield stress of 60 ksi (414 MPa)
No. 5 or No. 6 bars The steel constitutes about 0.6 - 0.7 percent of the pavement cross-sectional
area and is typically placed at slab mid-depth or shallower. At least 63 mm (2.5 inches) of PCC
cover should be maintained over the reinforcing steel to minimize the potential for steel
corrosion by chlorides found in deicing agents .
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1.6.2 DESIGN OF PAVEMENT
A. Design Of Flexible Pavement :-
The thickness of pavement is designed on the basis of projected number of commercial
vehicles for the design life using the current commercial vehicles per day and its growth rate.
Further, it requires the sub grade strength value is term of CBR. It is expected that rural road
will not have more than 450 CBPD in any case. The design chart given in Figure-3 may be
referred to obtained the total pavement crust thickness (granular curst thickness) required
over the sub-grade for the design life of the pavement. Based on the strength of granular
materials the are used, the total design thickness is divided into base and sub base thickness.
However any other higher type of bituminous layer can be part of the designed thickness.
However, any other higher type of bituminous layer can be part of the designed thickness,
with exception of thin bituminous surfacing (PMC, MSS, etc). In case of rural roads with low
volume of traffic, structural layer bituminous mix and not be provided, generally except is
very special cases where the traffic volume is so high that the design suggest it whole range
of traffic and CBR that exist for rural roads in various States of the country have been
considered and flexible pavement thickness catalogues are given in Figures-14,15,16 for
ready reference.
Fig.13: CBR Curve For Flexible pavement Design
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2014 UNSTABILIZED SOIL
A B C D
A B C D
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
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A B C D
Sub Base Course Base Course Surfacing
Fig 14: Thickness of crust required for different traffic
A
B
C
D
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
2014 UNSTABILIZED SOIL
A B C D
A B C D
Sub Base Course Base Course Surfacing
Fig 15: Thickness of crust required for different traffic
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
2014 UNSTABILIZED SOIL
A B C D
A B C D
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
2014 UNSTABILIZED SOIL
A B C D
Sub Base Course Base Course Surfacing
Fig 16: Thickness of crust required for different traffic
TYPICAL CROSS-SECTION OF ROAD
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
2014 UNSTABILIZED SOIL
B. Design Of Rigid Pavement:-
Design the following details of a plain cement concrete pavement for a two lane highway.
(a)Pavement slab thickness
(b)Dowel bars for expansion joints
(c)Tie bars for longitudinal joints
Follow the design procedure recommended by IRC where ever applicable. Use the given data,
IRC load stress charts for edge and corner regions, and assume any other data not provided here.
Width of expansion joint gap = 2.5 cm
Maximum variation in temperature between
summer and winter = 35 C
Thermal coefficient of concrete = 10x10" per C
Allowable tensile stress in CC during curing = 0.8 kg/cm
Coefficient of friction = 1.5
Unit weight of CC = 2400 kg/cm3
Design wheel load - 5100 kg
Radius of contact area = 15 cm
Present traffic intensity, = 950 commercial vehicles/day
Modulus of reaction of sub-base course = 8 kg/cm3
Flexural strength (allowable flexural stress) of concrete = 40 kg/cm2
E value of concrete = 3 x 105kg/cm
2
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
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/ \ivalue = 0.15
Design load transfer through dowel system = 40%
Permissible flexural stress in dowel bar = 1400 kg/cm2
Permissible shear stress in dowel bar - 1000 kg/cm2
Permissible tensile stress in steel (tie bar) = 1400 kg/cm2
Permissible bond stress in deformed (tie bars) = 24.6 kg/cm2
Temperature differential values in the region:
Slab thickness, cm 15 20 25
Temperature differential in slab in the region, C 14.6 15.8 16.3
(a) Joint Spacing
1joint 2.51.25cm2 2
Spacing of expansion joint Ls
1.25
35.7m100C(T 100x10x10
x35T )
2 1
which is less than maximum specified spacing of 140 m and so acceptable. Contraction joint
spacing in plain CC,
Lc=2S
c
x104
2x0.8x1044.45m
W.f 2400x1.5
which is less than maximum specified spacing of 4.5 m and hence acceptable.
Therefore provide contraction joints at 4.45 m spacing and expansion joints at every 8th such
joints i.e., 4.45 x 8 = 35.5 m spacing (instead of 35.7 m)
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Cx= 0.80 (from chart Fig. 7.25); Cyat Ly// of 4.29 = 0.6
Temperature differential for 24 cm thick slab (by interpolation) = 16.2C
Ste =1/2 x3x 105xl 0 x 10
-6x 16.2x0.8 = 19.44 kg/cm
2
Residual strength at the edge
= 40.0-19.44 = 20.56 kg/cm2
Load stress at edge, using stress chart (Fig. 7.23)
for h = 4,K = 8,Se=19.2kg/cm2
Factor of safety available 20.56
1.07which is safe and acceptable value19.2
Therefore provide a tentative design thickness of 24 cm.
Check for comer load stress : Using IRC stress chart Fig. 7.24, for h = 24, K = 8, the value of Sc
= 23.0 kg per cm .
Comer warping stress Ste=
E.e.t. 1
3(1 ) l
3x155x10x10
6x16.2
15
7.1kg/ cm2
3(10.15) 81.53
The worst combination of stresses at the comer is 23.0 + 7.1 = 30.1 kg/cm2, which is also less
than the allowable flexural strength of 40 kg/cm and hence the design is safe.
Adjustment for Trafficintensity Ad= P'[(l+r)]
(n+20)
Assuming a growth factor r = 7.5% and the number of years after the last count before the new
pavement is opened to traffic, n = 3.
Ad=9507.5 (n20)
1 5013cv/ day100
This traffic intensity being in the range > 4500, falls in group G and die adjustment factor is + 2
cm.
Therefore the revised design thickness of the slab
= 24 + 2 = 26 cm (c)
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
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(c)Dowel bars
Assume dowel bar diameter = 2.5 cm
Joint width, 8 = 2.5 cm
For Equal capacity in bending and bearing
1F (L
d 1.5)Ld =5d 1xF
b (Ld 8.8) 1
1400 L 1.5x2.5=5x2.5
d
100 Ld8.8x2.5
By substituting different values of Ld by trials (as in Example 7.22), the value of Ldi found to be
42.2 cm.
Length of dowel bar = Ld+ = 42.2 + 2.5 = 44.7 cm Therefore provide 45 cmlong dowel bars of diameter 2.5 cm
Actual value of Ld+ 45.0 - 2.5 = 42.5 cm Load transfer capacity of single
dowel:
P'(shear) = 0.785 d2Fs
= 0.785 x 2.52x 1000 = 4906 kg
2d2F 2x2.5
5x1400
P' (bending) 1 678kgLd8.8 42.5 8.8x2.5F .L .d 100x42.5 x2.5
P' (baring) b d 781kg12.5(Ld1.5) 12.5(42.5 1.5x2.5)
Taking the lowest value for design, P (design) =678 kg.
Load capacity factor required:
40
Load capacity of the dowel group = 5100 x -----= 2040 kg
100
Capacity factor required = =3.0
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
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Spacing of dowel bars :
Radius of relative stiffness for revised slab thickness o 1 24 cm,
3x105x26
3 14
l 86.6cm2)12x8(1 0.15
Effective distance up to which there is load
transfer = 1.8 /= 1.8x86.6 155.9 cm
Assuming a trial spacing of 35 cm between the dowel bars, the capacity available for the group
1 155.9 35
155.9 70
155.9 105
155.9 140
155.9 155.9 155.9 155.9
= 2.77< the required value of 3.0.
Assume dowel bar spacing of 30 cm.
155.9-30155.9-60155.9-90 ,
Capacity factor = 1 + ------- + ------ -----' ------------ +
As this value is greater than the required capacity factor of 3.0, 30 cm spacing of the dowel bars
is adequate. Therefore provide 2.5 cm dia. Dowel bars at expansion joints, of total length 45 cm
at a spacing of 30 cm centres.
(d) Tie Bars
Area of steel .per metre length longitudinal joint,b.f.h.W 3.5x1.5x26x2400 , ,
As=............... = .......................... = 2.34 cm2per m length
100SSS100x1400
Assuming 1 cm diameter of the bars, cross sectional area of each tie bar as =
0.785cm2. Perimeter of the tie bar = 3.14cm
Number of tie bars required per meter length of joint
A
s
2.342.98as0.785
Spacing of tie bar = -------------- = 33.5 cm
Provide a spacing of tie bar, say 33 cm
The length of tie bar may be increased by 5 cm for tolerance in placement.
Therefore provide 1 cm diameter deformed tie bars, 34 cm in length at a spacing of 33 cm.
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1.6.3 ADVANTAGES OF PAVEMENT
Flexible pavement
Load is transferred by grain to grain contact
Force of friction is less deformation in the sub grade is not transferred to the upper layers.
Expansion joints are not needed
Road can be used for traffic within 24 hours
No thermal stresses are induced as the pavement have the ability to contract and expand
freely
Have low completion cost
Design is based on load distributing characteristics of the component layers
Deformation in the sub grade is transferred to the upper layers
Rigid pavement
Design is based on flexural strength or slab action
Have high flexural strength
Deformation in the subgrade is not transferred to subsequent layers
No such phenomenon of grain to grain load transfer exists
Rolling of the surfacing in not needed
Have low repairing cost
Life span is more
Surfacing can be directly laid on the sub grade
No damage from oils and greases.
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1.6.4 LIMITATIONS OF PAVEMENT
Flexible pavement
Have low flexural strength
Surfacing cannot be laid directly on the sub grade but a sub base is needed
Strength of the road is highly dependent on the strength of the sub grade
Repairing cost is high
Rolling of the surfacing is needed
Have low life span
Rigid pavement
Thermal stresses are more vulnerable to be induced as the ability to contract and expand
is very less in concrete
Expansion joints are needed
Strength of the road is less dependent on the strength of the sub grade
Road cannot be used until 14 days of curing
Force of friction is high
Completion cost is high
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1.6.5 LOAD DISTRIBUTION
Flexible Pavement:-
Flexible pavements are so named because the total pavement structure deflects, or flexes, under
loading. A flexible pavement structure is typically composed of several layers of material. Each
layer receives the loads from the above layer, spreads them out, then passes on these loads to the
next layer below. Thus, the further down in the pavement structure a particular layer is, the less
load (in terms of force per area) it must carry.
Figure 17: Flexible Pavement Load Distribution
In order to take maximum advantage of this property, material layers are usually arranged in
order of descending load bearing capacity with the highest load bearing capacity material (and
most expensive) on the top and the lowest load bearing capacity material (and least expensive)
on the bottom. This section describes the typical flexible pavement structure consisting of:
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Surface course. This is the top layer and the layer that comes in contact withtraffic. It
may be composed of one or several different HMA sub layers.
Base course. This is the layer directly below the HMA layer and generally consistsof
aggregate (either stabilized or unstabilized).
Subbase course. This is the layer (or layers) under the base layer. A subbase is
notalways needed.
Rigid Pavement:-
Rigid pavements are so named because the pavement structure deflects very little under loading
due to the high modulus of elasticity of their surface course. A rigid pavement structure is
typically composed of a PCC surface course built on top of either (1) the subgrade or (2) an
underlying base course. Because of its relative rigidity, the pavement structure distributes loads
over a wide area with only one, or at most two, structural layers
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Figure 18: Rigid Pavement Load Distribution
This section describes the typical rigid pavement structure consisting of:
Surface course. This is the top layer, which consists of the PCC slab.
Base course. This is the layer directly below the PCC layer and generally consists
ofaggregate or stabilized subgrade.
Sub base course. This is the layer (or layers) under the base layer. A sub base is
notalways needed and therefore may often be omitted.
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Comparison:-
The primary structural difference between a rigid and flexible pavement is the manner in
which each type of pavement distributes traffic loads over the sub-grade. A rigid pavement has a
very high stiffness and distributes loads over a relatively wide are of sub-grade a major portion
of the structural capacity is contributed by the slab itself.
Fig.19 Stress Distribution In Flexible And Rigid
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
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Fig.20 Stress Distribution In Flexible And Rigid
Fig. 21 Pavements Stress Overlap Due to Dual Wheel
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1.6.6 COSTING OF PAVEMENT
Flexible Pavement
The costs of different pavements are obtained by multiplying the volumes of materials by their
respective costs. The costs of the different materials were calculated using 2006 schedule of rates
for Dehradun district. Bageshwar Prasad2 used a maintenance cost of Rs 1.5 million for flexible
pavements and the same was uniformly added to all the pavements in this study. Therefore, the
costs computed in this study include both construction and maintenance costs. Table 3 gives the
costs of flexible pavements designed for different combinations of soil CBR and traffic
conditions. Fig shows the variation in cost of flexible pavements with respect to traffic loading.
Equation relates the cost of flexible pavements with soil CBR and traffic loading.
Cost = -16.98+12.136*CBR
-0.3
+15.476*msa
0.10
Table 1 Cost of Flexible Pavements in Million Rupees for Different Combinations of Soil
and Traffic
Soil Traffic Load(msa)
CBR 1 2 3 5 10 20 30 50 100 150
%
2 7.12 8.49 9.09 10.67 12.60 14.29 15.25 16.32 18.00 18.85
3 7.12 7.69 8.28 9.45 11.51 13.19 14.14 15.33 16.77 17.49
4 5.80 7.18 7.76 9.17 11.01 12.33 13.29 14.58 16.14 16.74
5 5.45 6.682 7.39 8.67 10.56 11.76 12.59 13.77 15.08 15.68
6 5.17 6.53 7.11 8.26 10.03 11.23 11.94 12.88 14.07 14.78
7 5.07 6.36 6.89 8.04 9.81 10.77 11.60 12.54 13.72 14.56
8 5.07 6.36 6.82 7.83 9.59 10.56 11.27 12.20 13.39 14.22
9 5.07 6.36 6.82 7.83 9.48 10.21 10.91 11.97 13.15 13.98
10 5.07 6.36 6.82 7.83 9.48 10.21 10.80 11.62 12.91 13.75
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Rigid Pavement
The cost of construction and maintenance are considered in this study. The cost of sub-grade, dry
lean concrete sub-base, pavement quality concrete slab, shoulders, dowel bars, and tie bars were
computed as per 2006 schedule of rates for Dehradun district. Maintenance cost is adopted from
a study made by Bageshwar Prasad2. The total cost of construction and maintenance costs for all
the pavements are shown in Table 4. Fig. 10 shows the cost of rigid pavements against traffic
loading for different values of sub-grade CBR. Equation 14 was developed using multiple
regression analysis.
Cost = 8.284 + 4.719 * CBR-0.9
+ 20.8 * msa0.15
Table 2 Cost of Rigid Pavements in Million Rupees for Different Combinations of Soil and
Traffic
Soil Traffic Load (msa)
CBR % 7 10 20 30 50 100 150
2 13.32 13.92 13.92 14.54 14.85 15.15 15.15
3 12.41 13.01 13.01 13.63 13.93 14.24 14.24
4 12.15 12.74 12.74 13.36 13.36 13.66 13.96
5 11.87 12.46 12.46 13.07 13.37 13.37 13.69
6 11.87 12.19 12.48 13.09 13.09 13.39 13.39
7 11.90 12.19 12.50 12.80 13.09 13.41 13.41
8 11.61 12.21 12.21 12.82 12.82 13.11 13.41
9 11.64 11.92 12.24 12.53 12.82 13.13 13.13
10 11.36 11.95 11.95 12.53 12.53 12.84 13.13
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COMPARISON:-
The design and cost computations for flexible and rigid pavements are discussed in Sections 3
and 4 respectively. The initial aim of this study was to determine the threshold values of CBR
and msa beyond which one of the pavements becomes economical in its combined construction
and maintenance cost. The points of equal cost on the CBR vsmsa graph were determined using
Equations 13 and 14 and these are plotted in Fig.11. Rigid pavements are found to be economical
in the upper portion of the graph and flexible pavements are economical in the lower portion of
the graph. Mathematically:
If msa12.48+6.05 x CBR, rigid pavement will be economical;
If msa=12.48+6.05 x CBR, both pavements will have the same cost.
The above mathematical equation is developed by fitting a straight line to the points of equal
costs. It has an R2 value of 0.998. The equation is valid for soil CBR values ranging from 2
percent to 10 percent.
Fig.22 Critical Line of Equal Costs (Swing Line)
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1.7 Considerations for Flexible vs. Rigid Pavements
Explains how the state Departments of Transportation have begun to implement the
practice of including rigid versus flexible pavement structure alternatives in construction plans in
order to provide flexibility in contractor competition. Ideally, the inclusion of alternate pavementdesigns early in the bidding process would allow DOTs to achieve a best -value bid price, but
there is concern that alternative pavement designs might not be truly equivalent. Several Life-
Cycle Cost Analysis (LCCA) studies have been conducted in order to determine whether the
alternate designs included in contracts will display comparable performance lives. In California,
pavement design alternatives are analyzed for design lives of 10, 20, and 40 years, in order to
determine the most cost-effective alternate pavement design life. Furthermore, the Colorado
Department of Transportation recommends a 40-year analysis period when comparing flexible
and rigid pavements, and the Alternate Design Alternate Bid (ADAB) procedure developed by
the Louisiana DOT appears to have been adopted as standard industry practice. This protocol
includes an analysis of general project information, an LCCA comparison of flexible and rigid
pavement designs, and a final engineering project evaluation. Equivalent pavement designs
should be considered for major highway projects, and projects with a high volume of trucks.
why one pavement is used versus another. Basically, state highway agencies generally
select pavement type either by policy, economics or both. Flexible pavements generally require
some sort of maintenance or rehabilitation every 10 to 15 years. Rigid pavements, on the other
hand, can often serve 20 to 40 years with little or no maintenance or rehabilitation. Thus, it
should come as no surprise that rigid pavements are often used in urban, high traffic areas. But,
naturally, there are trade-offs. For example, when a flexible pavement requires major
rehabilitation, the options are generally less expensive and quicker to perform than for rigid
pavements.
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
2014 UNSTABILIZED SOIL
1.8 SOIL STABILIZATION
1.8.1Type Of stabilization
Remove and replace
Lime Piles Mechanical stabilization
Admixture Stabilization (cement, lime, fly ash,bituminous)
1.8.2Pavement Performance (Lime-Stabilized Subgrades and Base/Sub base Layers)
The material properties of both lime-stabilized soils and lime-stabilized aggregates, as related to
their impact on overall pavement performance, can be divided into four categories (Little, 1999):
StrengthThe most obvious improvement in a lime-reactive soil or aggregate is strength
gain over time. The various strength parameters impacted by the pozzolanic reactions that
occur include unconfined compressive strength, tensile strength, flexural strength, and
CBR
Resilient modulus/stiffnessConcurrent with the strengthening of a soil brought about by
pozzolanic reactions, are changes in the stressstrain relationship of the material . Lime-
stabilized soils fail at much higher deviator stresses than their no stabilized counterparts,
and at a much lower strain (typically about 1 percent strain for the stabilized mixture
versus about 3 percent for the no stabilized material). Materials tested in the laboratory
(repeated-load triaxial and indirect tensile tests) and in the field (impulse deflection
testing, vibrational testing) both confirm significant increases over time in the resilient
properties of lime-treated materials
Fracture and fatigueFlexural fatigue strength is related to the number of loads that can be
carried by a material at a given stress level, and it is an important consideration in theevaluation of limesoil and limeaggregate mixtures. The strength-gain effects produced
by pozzolanic reactions are often substantial for reactive soils.
DurabilityThe ability of lime-stabilized materials to resist the detrimental effects of
moisture and freeze-thaw cycling over time has been evaluated in several ways, in both
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the laboratory and the field. The results of these evaluations have often shown only slight
detrimental effects of environment on the levels of strength/stiffness produced by the
addition of lime.
Table 3. Stabilization methods for pavements (from rolling, 1996).
Method Soil Effect Remarks
Blending Moderately None Too difficult to mixplastic
Others Improve gradation
Reduce plasticity
Reduce breakage
Lime Plastic Drying Rapid
Immediate strength gain Rapid
Reduce plasticity Rapid
Coarsen texture Rapid
Long-term pozzolanic Slow
cementing
Coarse with Same as with plastic soils Dependent on quantity of
fines plastic fines
Non plastic None
Cement Plastic Similar to lime Less pronounced
Cementing of grains Hydration of cement
Coarse Cementing of grains Hydration of cement
Bituminous Coarse Strengthen/bind, Asphalt cement or liquidwaterproof asphalt
Some fines Same as coarse Liquid asphalt
Fine None Can't mix
Pozzolanic and Silts and coarse Acts as a filler Denser and strongerSlags
Cementing of grains Slower than cement
Misc. methods Variable Variable Depends on mechanism
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November 1, COMPARATIVE STUDY BETWEEN FLEXIBLE AND RIGID PAVEMENT FOR STABILIZED AND
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CHAPTER 2
EXPERIMENTAL PROGRAMME
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2.1 SOIL PROPERTIES
2.1.1 Water Content/Moisture Content (w)
w = *100
w = * 100
2.1.2 Degree Of Saturation (s)
S = * 100
0 < S < 100%
2.1.3 Void Ratio (e)
e = * 100
2.1.4 Porosity (n)
n = * 100
0 < n < 1
2.1.5 Air Content (a)
a =
a + S = 1
2.1.6 Specific Gravity (G)
G=
2.1.7Density 2.1.7.1
Bulk Density
t =
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2.2 PARTICLE SIZE DISTRIBUTION (Sieve analysis)
2.2.1 Coarse Sieving
Sieves having square opening are arranged there decreasing size from top to bottom. The sieve
used are80mm , 20mm , 10mm ,&4.75mm the sample is shaken for 10min by hands
Table 4 Observation of coarse sieving
S.no Sieve no. Mass retain % Retain % Cumulative % passing
(gms) retain
1. 80mm 0 0 0 100%
2. 40mm 470gm 9.40 9.40 90.60
3. 20mm 925gm 18.50 27.90 72.10
4. 10mm 1412gm 28.24 56.14 43.60
5. 4.75mm 976gm 19.50 75.64 24.36
6. Pan 1219gm 24.36 100 0
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2.2.2 Fine Sieving
The particles passing from 4.75m sieve are further analyzed and the sieve of 2mm , 1mm, 6oo,
425, 212, 150, 75 are arranged in decreasing order.
Table 5 Observation of fine sieving
S.no Sieve no. Mass retain % Retain % Cumulative % passing
(gms) retain
1. 2mm
2. 1mm
3. 600
4. 425
5. 212
6. 150
7. 75
8. Pan
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2.3 CBR TEST
INTRODUCTION
The California Bearing Ratio, believe it or not, was developed by The California State HighwaysDepartment.It is in essence a simple penetration test developed to evaluate the strength of roadsubgrades. CBR-value is used as an index of soil strength and bearing capacity. This value isbroadly used and applied in design of the base and the sub-base material for pavement.
THE BASIC CBR TESTThis consists of causing a plunger of standard area to penetrate a soil sample, (this can be in the
laboratory or on site). The force (load) required to cause the penetration is plotted against
measured penetration, the readings noted at regular time intervals.
This information is plotted on a standard graph, and the plot of the test data will establish the
CBR result of the soil tested.
THE REASON FOR THE CBR TEST
It sounds complicated, but the basis behind it is quite simple.
We are determining the resistance of the subgrade, (i.e. the layer of naturally occurring material
upon which the road is built), to deformation under the load from vehicle wheels.
Even more simply put, ''How strong is the ground upon which we are going to build the road''.
The stronger the subgrade (the higher the CBR reading ) the less thick it is necessary to design
and construct the road pavement, this gives a considerable cost saving.
Conversely if CBR testing indicates the subgrade is weak (a low CBR reading) we must
construct a suitable thicker road pavement to spread the wheel load over a greater area of the
weak subgrade in order that the weak subgrade material is not deformed, causing the road
pavement to fail.
CBR VALUE SUBGRADE STRENGTH COMMENTS
3% and less Poor " Capping is required
3%- 5% NormalWidely encountered CBR range cappingconsidered according to road category
5%- 15% Good"Capping" normally unnecessary except on veryheavily trafficked roads.
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2.3.1 CBR of unstabilized soil
CBR-values of untreated compacted soils need to be interpreted in the context of the general
relationship between the CBR-values and the consistency (quality) of the soils used in pavement
applications (Bowles, 1992). CBR-values ranging from 3 to 7% are considered as a poor to fairconsistency.
2.3.2 CBR of stabilized soil
Soil-lime mixtures of the three tested soils were prepared at the optimum lime content,
2%, and 4% above the optimum lime content and cured for 7 days.
The addition of the optimum lime content led to an increase in the CBR-values for the three
tested soils. The lime-tertiary clay mixtures have the highest CBR-values, whereas the lime-
weathered soil mixtures have the lowest values. The reactivity of the tertiary clay with lime is
stronger than the reactivity of both the weathered soil and the organic silt. The CBR -values of
lime-tertiary clay mixtures increased slightly with increasing lime content (2 and 4% above the
optimum lime content).
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CHAPTER 3
RESULTS
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Table 6 Physical properties of various soils
S. Properties Banga Garshankar Nawanshahar
No. Garshankar road Nawanshahar road Phagwara road soilsoil soil
1. Plasticity Clay of low Plasticity Clay of low Plasticity Clay of low plasticity
2. Specific gravity (G) 2.58 g/cm3 2.40 g/cm3 2.55 g/cm3
3. Liquid limit L. L 32.5% . 27% 31%
4. Plastic limit P. L. 14.5% 18% 17%
5. Plasticity index P. I. 18% 9% 14%
6. Optimum moisture
Content (OMC) 14% 14% 12%
7. Maximum dry density 1.72 g/cm3 1.68 g/cm3 1.75 g/cm3
Table 7. Liquid limit (L.L.), plastic limit (P.L.), plasticity index (P.I.) atdifferent percentage of lime
S. No. Percentage of Banga- Garshankar Nawanshahar-
Lime Garshankar Nawanshahar PhagwaraRoad soil road soil road soil
L.L. P.L. P.I. L.L. P.L. P.I. L.L. P.L. P.I.
1 0 32.0 18.0 14.0 27.0 18.0 9.0 31.0 17.0 14.0
2 1 32.8 26.0 6.8 33.0 27.0 6.0 31.3 24.0 7.3
3 2 33.0 29.0 4.0 36.0 30.5 5.5 31.5 28.0 3.5
4 3 33.0 30.5 2.5 36.5 31.5 5.0 31.5 29.5 2.0
5 4 33.0 31.0 2.0 36.9 32.2 1.7 31.5 30.0 1.5
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3.2 Benefits of stabilization
Lower material costs
when soil stabilization is taken into account during the pavement design, a significant
reduction in the required amount of base thickness and pavement surface materials willresult
Lower construction costs
when compared to traditional methods of complete removal and replacement or
traditional undercuts, a cost savings of 30 to 50 percent may be achieved
Reduced logistics costs and increased environmental responsibility
stabilizing the existing soil eliminates the need to export the poor undesirable soils or
import new usable fill material
Increased strength
a dramatic increase in CBR (California Bearing Ratio) can be achieved, changing
unstable CBR values of 7 or less into highly stable CBR values
Longer durability
stabilized soil is highly resistant to water and frost (often the main causes of pavement
failure), which increases the lifespan of the subgrade
Safer operations
the improved soil surface reduces the risks associated with persons slipping and falling,
vehicles skidding, collisions and other accidents; emergency vehicles are able to travel
the finished subgrade without restraint
More reliable construction
stabilized fills are less likely to suffer trench cave-ins and undesirable shifting of
construction elements
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Greater convenience
in many circumstances, roads that are stabilized do not have to be shut down to traffic;
even before they are paved, stabilized soil surfaces support foot and vehicle traffic, which
helps to virtually eliminate complaints from nearby residents, employees and visitors
3.2.1 Analysis of results for physical properties of soil with lime stabilization
It is observed from Table 2 that with increase in lime content, optimum moisture
content increases and maximum dry density decreases
The liquid and plastic limit increased sharply for all the samples with lime content up to
2 per cent and the increase was negligibly small beyond 2 per cent lime content.
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3.3 Effects on CBR value due lime stabilization
3.3.1 CBR of Soil +20% lime
The results of CBR tests for soil with 20% lime for three samples at different compaction efforts
(10, 30 and 65 blows. By plotting the results as discussed earlier, the CBR value is determined
at 25 blows to be 15.
3.3.2 CBR of Soil +30% lime
The results of CBR tests for soil with 30% lime for three samples at different compaction
efforts (10, 30 and 65 blows). By plotting the results as discussed earlier, the CBR value is
determined at 25 blows to be 18.
Fig 23 Variation of CBR w.r.t % of lime
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Table 8. Variation of thickness of pavement for unstabilized soil
Table 9. Variation of thickness of pavement for stabilized soil
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CHAPTER 4
CONCLUSION
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It is observed with increase in lime content, optimum moisture content increases
and maximum dry density decreases.
The liquid and plastic limit increased sharply for all the samples with lime content upto
2 per cent and the increase was negligibly small beyond 2 per cent lime content.
The problem of settlement of roads is prevalent due to soil stabilization.
If CBR value is found maximum without stabilization flexible pavement provided as
for economically.
If CBR value is found minimum without stabilization rigid pavement provided as
for good strength and economically.
If the soil is stabilized than the problem for settlement is prevents for any type
of pavement.
For required thickness of soil 2% of lime is required for addition.
Soil properties have been improved with soil stabilization.
Permeability decreased.
Improvement in soil properties by adding Lime.
Effect of lime is less for cohesion less soils.
Curing Period increase in fatigue life up to 4 to 6 weeks of curing.
The road constructed with enzyme stabilized soil has monitored for its performance at
regular interval for 8-10 months. The road is performing well and field CBR test
indicates that stabilized soil can be used as sub base material very effectively. But prior
laboratory study is necessary to get the good result in the field
Geotechnical properties of soil are increasing by stabilization of soil.
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References
http://www.civil.iitb.ac.in/~dns/IACMAG08/pdfs/N13.pdf
Research paper- Jordan Journal of Civil Engineering, Volume 6, No. 1, 2012
Research paper- highway research journal Vol 5 - No 2.
Research paper- Comparative Study of Flexible and Rigid Pavements For Different
Soil and Traffic Conditions.
Indian Standard handbook for civil engineers by: Khanna
HIGHWAY ENGINERRING BY : S.K. Khanna, C.E.G. Justo
Highway material testing laboratory manual by: S.K. Khanna
Ministry of Road Transport And Highway 4th Revised Publish By IRC (New
Delhi) 2001.
ER.Yogesh Sharma
ER. Pushpendra Sir