Design and analysis of flexible pavement

A
PROJECT REPORT
on
DESIGN AND ANALYSIS OF FLEXIBLE PAVEMENT
By
Anshuman Ojha (1742300006)
Deepanshu Pandey (1742300007)
Devesh Kumar Chaurasia (1742300008)
Himanshu Gautam (1742300009)
Submitted to the Department of Civil Engineering in Partial
Fulfillment of the Requirements for the Degree of
Bachelor of Technology
in
Civil Engineering
School of Management Sciences (SMS Institute of Technology)
Sultanpur Road, Lucknow – 226501,
Uttar Pradesh, INDIA.
Affilated to Dr. A.P.J. Abdul Kalam Technical University,
Lucknow
JANUARY - 2021

TABLE OF CONTENTS
CONTENTS PAGE NO
CERTIFICATE iv
DECLARATION V
ACKNOWLEDGEMENT Vi
ABSTRACT Vii
LIST OF ABBREVIATIONS Viii
CHAPTER 1 :- INTRODUCTION 1-3
1.1. INTRODUCTION 1
1.2. TYPES OF PAVEMENTS 1
1.3. SCOPE & APPLICABILITY 3
CHAPTER 2 :- CROSS-SECTION OF A FLEXIBLE PAVEMENT 4-10
2.1. TYPES OF COATS 4
2.2. DIFFERENT COURSES OF LAYERS 5
CHAPTER 3 :- SURVEYING & LEVELING 7
3.1. SITE LOCATION 7
3.2. TOPOGRAPHIC SURVEY 8
CHAPTER 4 :- IMPORTANT TESTS 11-18
4.1. GENERAL 11
4.2. TESTS 11
CHAPTER 5 :- DESIGN APPROACH & CRITERIA 19-25
5.1. DESIGN APPROACH & CRITERIA 19
ii

5.2. DESIGN WHEEL LOAD 22
5.3. PAVEMENT DESIGN 23
5.4. IRC METHOD OF DESIGN 23
5.4. DESIGN TRAFFIC 24
CHAPTER 6 :- FAILURES OF FLEXIBLE PAVEMENT 26-34
6.1. ALLIGATOR CRACKING 26
6.2. TYPES OF FAILURES 27
CHAPTER 7 :- MACHINES 35-48
7.1. MACHINERIES USED 35
7.2. SOME OTHER MACHINES 39
CHAPTER 8 :- CONCLUSION 40
REFRENCES 41
iii

CERTIFICATE
This is to certify that project report entitled “Design and Analysis of Flexible
Pavement” which is submitted by Anshuman Ojha, Deepanshu Pandey,
Devesh Kumar Chaurasia, Himanshu Gautam in partial fulfillment of the
requirement for the award of degree of Bachelor of Technology in Civil
Engineering from SCHOOL OF MANAGEMENT SCIENCES (SMS INSITUTE
OF TECHNOLOGY), LUCKNOW under Dr. A.P.J. Abdul Kalam Technical
University, Lucknow is a record of the candidate own work carried out by him
under our supervision. The matter embodied in this thesis is original and has
not been submitted for the award of any other degree.
HEAD OF DEPARTMENT
Dr. ASHA KULSHRESHTHA
CIVIL ENGINEERING DEPARTMENT
SUPERVISOR
Mr. SHUJA ASKARI
Asst. PROFESSOR
iv

DECLARATION
We hereby declare that this submission is our own work and that, to the best of our knowledge
and belief, it contains no material previously published or written by another person nor
material which to a substantial extent has been accepted for the award of any other degree of
the university or other institute of higher learning, except where due acknowledgment has been
made in the text.
NAME OF STUDENT ROLL NUMBER SIGNATURE
Anshuman Ojha 1742300006 ………………
Deepanshu Pandey 1742300007 ………………
Devesh Kumar Chaurasia 1742300008 ………………
Himanshu Gautam 1742300009 ………………
v

ACKNOWLEDGEMENT
It gives us a great sense of pleasure to present the report of the B. Tech Project
undertaken during B.Tech. Final Year. We owe special debt of gratitude to Mr.
SHUJA ASKARI, Asst. Professor of Department of Civil Engineering, SCHOOL
OF MANAGEMENT SCIENCES (SMS INSITUTE OF TECHNOLOGY),
LUCKNOW for their constant support and guidance throughout the course of our
work. Their sincerity, thoroughness and perseverance have been a constant source
of inspiration for us. It is only their cognizant efforts that our endeavors have seen
light of the day.
We also do not like to miss the opportunity to acknowledge the contribution of all
faculty members of the department for their kind assistance and cooperation
during the development of our project. Last but not the least, we acknowledge our
friends for their contribution in the completion of the project.
We feel elated to extend our floral guidance to Dr.ASHA KULSHRESHTHA,
Head of Department of Civil Engineering, for his encouragement all the way
during analysis of the project. His annotations, insinuations and criticism are the
key behind the successful completion of doing the thesis and for providing us all
the required facilities.
vi

ABSTRACT
The satisfactory performance of the pavement will result in higher savings in
terms of vehicle operating costs and travel time, which has a bearing on the overall
economic feasibility of the project. A thorough analysis of the existing pavement
is greatly required at this point of time, as an excessive amount of vehicle loads is
passing through the project site and it is unknown whether or not the road
pavement might sustain its structural integrity. The critical line of equal costs on
the plane of CBR versus msa is also identified. This is a swing line which
delineates the economic feasibility of two types of pavements.
It has been found that the pressure vs settlement curve; pressure vs nodal stress
curve ; pressure vs element stress curve are linear for small pressure range and
then it become nonlinear. More nonlinearity is seen at higher pressure. Hence
material nonlinearity must be considered while analysing and designing flexible
pavements. This total work includes collection of data analysis of various flexible
and rigid pavement designs and their estimation procedure are very much useful
to the engineer who deals with highways and road construction techniques.
vii

ABBREVIATION
AADT Annual Average Daily Traffic
AASHTO American Association of State Highway and
Transportation Officials
ADT Average Daily Traffic
BC Bituminous Concrete
BM Bituminous Macadam
CBR California Bearing Ratio
DBM Dense Bituminous Macadam
DoR Department of Roads
EM Elastic Modulus
EF Equivalent Factor
ESA Equivalent Standard Axles
FHWA Federal Highway Administration
GB Granular Base
GSB Granular Sub Base
IRC Indian Road Congress
MPa Mega Pascal
MSA Million Standard Axles
ORN Overseas Road Notes
PC Premix Carpet
SDBC Semi-Dense Bituminous Concrete
SSRBW Standard Specification for Road and Bridge Works
TRB Transportation Research Board
TRL Transportation Research Laboratory
VDF Vehicle Damage Factor
WBM Water Bound Macadam
viii

LIST OF FIGURES
S. NO. CONTENT PAGE NO
1. Flexible Pavement 2
2. Rigid Pavement 2
3. Cross-Section of Flexible Pavement 4
4. Site Location 7
5. Auto Level 9
6. Vibratory Sieve Shaker 12
7. Bitumen Extractor 13
8. CBR Mould 16
9. CBR Test Apparatus 17
10. Graph of Penetration and Load by CBR Test 18
11. Structural Elements of Road 20
12. Axle configuration 22
13. Equivalent Single Wheel Load (ESWL) 22
14. Flexible Pavement Thickness Graph 25
15. Longitudinal Cracks 27
16. Fatigue Crack 28
17. Transverse Cracks 28
18. Reflection Crack 29
19. Block Cracks 29
20.Edge Crack 30
21. Rutting 30
22.Corrugatin 31
ix

23. Shoving 31
24. Depressions 31
25. Overlay Bump 32
26. Declamations 32
27. Pot Holes 33
28. Patching 33
29. Pumping 34
30. Bleeding and Flushing 34
31. Back Hoe Loader 36
32. Paver Machine 37
33. Vibratory Roller 39
34. Bitumen Sprayer 39
x

LIST OF TABLES
S. NO. CONTENT PAGE NO
1. Survey by Auto Level 10
2. Sieve Analysis 12
3. Observation And Calculations of Maximum Dry Density Test 15
4. Observations of CBR Test 17
5. Equivalent Standard Axles 22
xi

CHAPTER-1
INTRODUCTION
1.1. INTRODUCTION
A road surface or pavement is the durable surface material laid down on an area
intended to sustain vehicular or foot traffic, such as a road or walkway. In the past,
gravel road surfaces, cobblestone and granite setts were extensively used, but these
surfaces have mostly been replaced by asphalt or concrete laid on a compacted base
course. Road surfaces are frequently marked to guide traffic. Today, permeable paving
methods are beginning to be used for low-impact roadways and walkways.
1.2. TYPES OF PAVEMENT
1.2.1. Flexible Pavements
Flexible pavement can be defined as the one consisting of a mixture of asphaltic or
bituminous material and aggregates placed on a bed of compacted granular material
of appropriate quality in layers over the subgrade. Water bound macadam roads and
stabilized soil roads with or without asphaltic toppings are examples of flexible
pavements. The design of flexible pavement is based on the principle that for a load of
any magnitude, the intensity of a load diminishes as the load is transmitted downwards
from the surface by virtue of spreading over an increasingly larger area, by carrying it
deep enough into the ground through successive layers of granular material. Thus for
flexible pavement, there can be grading in the quality of materials used, the materials
with high degree of strength is used at or near the surface. Thus the strength of
subgrade primarily influences the thickness of the flexible pavement.
1

Fig 1. Flexible Pavement
1.2.2. Rigid Pavements
A rigid pavement is constructed from cement concrete or reinforced concrete slabs.
Grouted concrete roads are in the category of semi-rigid pavements. The design of rigid
pavement is based on providing a structural cement concrete slab of sufficient strength
to resists the loads from traffic. The rigid pavement has rigidity and high modulus of
elasticity to distribute the load over a relatively wide area of soil. Minor variations in
subgrade strength have little influence on the structural capacity of a rigid pavement.
In the design of a rigid pavement, the flexural strength of concrete is the major factor
and not the strength of subgrade. Due to this property of pavement, when the subgrade
deflects beneath the rigid pavement, the concrete slab is able to bridge over the
localized failures and areas of inadequate support from subgrade because of slab
action.
Fig 2. Rigid Pavement
2

1.3. SCOPE & APPLICABILITY
This manual will apply to design of flexible pavements for National Highways and
Feeder Roads. Furthermore, this manual could be followed for the design of Arterial
and Sub arterial roads of the urban road categories. For the purpose of guidelines,
flexible pavements are considered to include the pavements which have bituminous
surfacing and granular base and sub-base courses conforming to Standard
Specifications for Road and bridges Works published by the Department of Roads in
2001. These guidelines apply to new pavements. The manual may require revision from
time to time in the light of future experience and development in the field. The principal
users of this manual are the Pavement Design Engineers from government or their
agents (i.e. Consultants).
The design procedures incorporated in this document are based on the IRC 37-2001
guidelines, American Association of State Highway and Transportation Officials
(AASHTO) Guide for Design of Pavement Structures, Transportation Research Board
(TRB), Federal Highway Administration (FHWA) publications, Pavement Structural
Design’ of the Austroads Guide to Pavement Technology (Austroads, 2008) and Road
Note 31 (TRL, UK).
3

CHAPTER-2
CROSS-SECTION OF A FLEXIBLE PAVEMENT
Typical layers of a conventional flexible pavement includes seal coat, surface course,
tack coat, binder course, prime coat, base course, sub-base course, compacted sub-
grade, and natural sub-grade.
Fig 3. Cross-Section of Flexible Pavement
2.1. TYPES OF COATS
2.1.1. Seal Coat
The seal coat has to be provided which is a thin surface treatment used to water-proof
the surface and to provide skid resistance.
2.1.2. Tack Coat
Tack coat has to be provided between two layers of binder course. It coat is very light
application of asphalt, usually asphalt emulsion diluted with water. It must be thin,
uniformly cover the entire surface, and set very fast.
4

2.1.3. Prime Coat
Prime coat provides bonding between two layers which penetrates into the layer below,
plugs the voids, and forms a water tight surface. That’s why both prime coat and tack
coat has to be provided. They both have different functions.
It is an application of low viscous cutback bitumen to an absorbent surface like
granular bases on which binder layer is placed.
2.2. DIFFERENT COURSES OF LAYERS
2.2.1. Surface Course
Surface course is the layer directly in contact with traffic loads and generally contains
superior quality materials. They have to be constructed with dense graded asphalt
concrete (AC). The functions and requirements of this layer are:
It provides characteristics such as friction, smoothness, drainage, etc. Also it will
prevent the entrance of excessive quantities of surface water into the underlying are,
sub-base and sub-grade.
It must be though to resist the distortion under traffic and provide a smooth and skid-
resistant riding surface, it must be water proof to protect the entire base and sub-grade
from the weakening effect of water.
As per our design, combined thickness of base and surfacing should be 30 cm.
2.2.2. Binder Course
The binder course having aggregates less than asphalt has to be used as it doesn’t
require quality as high as the surface course, so replacing a part of surface course by
the binder course results in more economical design. This layer provides the bulk of
the asphalt concrete structure. Its chief purpose is to distribute load to the base course.
5

2.2.3. Base Course
The base course is the layer of material immediately beneath the surface of binder
course and it provides additional load distribution and contributes to the sub-surface
drainage. It may be composed of crushed stone, crushed slag, and other untreated or
stabilized materials.
2.2.4. Sub-Base Course
The Sub-base course is the layer of material which has to be provided beneath the base
course and its primary functions are to provide structural support, improve drainage,
and reduce the intrusion of fines from the sub-grade in the pavement structure. As per
our design 20 cm thick sub base course has to be provided.
2.2.5. Sub-Grade
The top soil sub-grade is a layer of natural soil prepared to receive the stresses from
the layers above. It is essential that at no time soil sub-grade is overstressed. It should
be compacted to the desirable density, near the optimum moisture.
6

CHAPTER-3
SURVEYING & LEVELLING
3.1 SITE LOCATION
Fig 4. Site Location
❖
Total Length of Road = 750 meter
❖
Road width= 3.7 meter
7

Road connectivity is a key component of development by promoting access to economic
and social services and thereby generating increased agricultural incomes and
productive employment. The project road is a link road to all the buildings of SMS,
LUCKNOW campus. This road directly connects all the possible ways of the campus
which provides a smooth passage to all belongings of the campus.
3.2 TOPOGRAPHIC SURVEY
3.2.1 General
Survey was done and temporary bench marks were established. Levels for cross section
have been taken at every 10 m intervals at various locations. Road plans & L-Sections
have been developed on AutoCAD.
3.2.2 Traversing
Traverse survey was done, chain survey starting coordinate was assumed and
according to the coordinates of other reference temporary bench mark was established.
3.2.3 Leveling
All leveling for establishing Benchmark are carried out having accuracy ± 5 mm/km.
We started the work by assuming arbitrary level, as no GTS benchmark was available
on the nearby location of the road.
Leveling work is carried over using a technical instrument named AUTO LEVEL by
taking an initial bench mark of 126 meter from the standard railway mean sea level of
Lucknow Railway Station.
3.2.3.1 Auto Level
An auto level is similar to the dumpy level, with its telescope fixed to the tribrach. For
more precise leveling of the instrument a spirit level is attached to the telescope. It is
used to measure the reduced level of any plane.
8

An automatic level, self- leveling level or builder's auto level includes an internal
compensator mechanism (a swinging prism) that, when set close to level, automatically
removes any remaining variation from level. This reduces the need to set the
instrument truly level, as with a dumpy or tilting level. Self- leveling instruments are
the preferred instrument on building sites, construction and surveying due to ease of
use and rapid setup time.
Fig 5. Auto Level
Using the formula
Height of the Instrument = Back Sight + Reduced Level
i.e. HI=BS+RL
Bench Mark = 224.34 m
9

S. Back Intermediate Fore Sight Reduced Remark
No. Sight Site Level
1. 0.908 HI=224.34+.908
2. 1.39 223.858 HI=225.248
3. 1.39 223.858
4. 1.402 1.36 CP 1 (HI=225.742)
5. 1.418 224.324
6. 1.485 224.257
7. 1.618 224.124
8. 1.53 1.405 CP 2 (HI=225.87)
9. 1.713 224.157
10. 1.523 1.257 CP 3 (HI=225.863)
11. 1.67 224.193
12. 1.296 1.42 CP 4 (HI=225.636)
13. 1.187 224.449
14. 1.386 1.46 CP 5 (HI=225.726)
15. 1.313 224.413
16. 1.475 224.251
17. 1.48 224.246
18. 1.412 1.421 CP 6 (HI=225.752)
19. 1.420 224.332
20. 1.326 1.462 CP 7 (HI=225.666)
21. 1.32 224.346
22. 1.46 1.445 CP 8 (HI=225.8)
23. 1.42 224.38
24. 1.448 1.46 CP 9 (HI=225.788)
25. 1.50 224.288
26. 1.48 1.46 CP 10 (HI=225.82)
27. 1.20 224.62
28. 1.165 1.581 CP11 (HI=225.505)
29. 0.86 224.645
30. 0.74 224.765
Table 1. Survey by Auto Level
10

CHAPTER-4
IMPORTANT TESTS
4.1. GENERAL
After selection of the final centre line of the road investigation for soil and other
materials require for construction are carried out in respect of the likely sources and
the availability and suitability of materials. The characteristics of the materials can be
qualitatively determined by appropriate testing procedures, the result of which
supplement knowledge of the material gained from visual inspection and a study of the
geological/geophysical environment.
4.2. TESTS
There are several types of tests which are being performed for identifying the
properties of soil, bitumen etc. Some tests are performed on the site and some are
performed in the laboratory. Some of the important tests are described below
1. Sieve Analysis
2. Bitumen Test
3. Maximum Dry Density Test
4. CBR Test
4.2.1. Sieve Analysis
• In this method we determine the density of the aggregate.
• In this there are different sizes of sieves.
• The material passes through these sieves and we calculate the % weight passing
through these sieves, and we compare these values with JMF Value.
• First of all we take a sample about 10 kg.
11

• Now we pass the sample from different sieves.
• After passing each sieve we find the retained weight, % weight retained, cumulative
weight retained and percentage passing of aggregates.
S. SIEVE SIZE WT. % WT. CUM. % % WT.
NO. (MM) RET. RET. WT. RET. PASSING
1. 19.5 0 0 0 100
2. 13.2 .350 3.681 3.681 96.319
3. 9.5 2.056 21.628 25.309 74.691
4. 4.75 3.954 41.594 66.903 33.097
5. 2.36 1.496 15.737 82.64 17.36
6. 1.18 1.65 17.357 99.997 0.003
Total 9.506
Table 2. Sieve Analysis
Fig 6. Vibratory Sieve Shaker
12

4.2.2. Bitumen Test
• Object
In this test we determine the bitumen content present in the bitumen
concrete mixture.
• Apparatus
Bitumen extractor machine
• Requirements
Filter paper, petrol/diesel, aggregate - bitumen mixture.
• Procedure
1. First of all we are weighing the weight of empty bowl.
2. Now we weight the empty bowl and sample.
3. Now we calculate the sample weight.
4. Now we add some petrol in the sample and stir until the aggregate shows
its initial appearance before mix with bitumen.
5. Now we fit the bowl in the machine and we rotate the bowl.
6. The bitumen comes out from mixture now we weighing the sample.
7. The loss in weight is the bitumen content.
Fig 7. Bitumen Extractor
13

Calculations
Weight of empty bowl = 1.156 kg
Empty bowl + sample weight = 1.710
kg Total sample weight = 0.554 kg
Bowl weight + sample weight after extraction = 1.674 kg
Sample weight after extraction = 1.674 - 1.156 = 0.518 kg
Difference = Total sample w eight – sample weight after
extraction Difference = 0.554 – 0.518 = 0.036 kg
% of bitumen =
ℎ × 100
0.036
% of bitumen = 0.554 × 100
= 6.498 %
Result
The % of bitumen in the sample = 6.498%
4.2.2.1. Some Properties of Bitumen
• Bitumen is a sticky, black, and highly viscous liquid or semi-solid form of
petroleum.
• It may be found in natural deposits or may be a refined product, and is classed as a
pitch. Before the 20th century, the term asphalt was also used.
• The primary use (70%) of asphalt is in road construction, where it is used as the
glue or binder mixed with aggregate particles to create asphalt concrete.
• Its other main uses are for bituminous waterproofing products, including
production of roofing felt and for sealing flat roofs.
14

• It consist chiefly high molecular weight hydrocarbons derived from distillation of
petroleum or natural asphalt.
• It is a semi-solid hydrocarbon product produced by removing the lighter fractions
(such as liquid petroleum gas, petrol and diesel) from heavy crude oil during the
refining process.
• Bitumen is often confused with Tar. Although bitumen and are similarly black and
sticky, they are distinctly different substances in origin, chemical composition and in
their properties.
• Tars are resides from the destructive distillation of organic substances such as coal,
wood, or petroleum.
4.2.3. Maximum Dry Density Test
Maximum dry density (MDD) corresponding optimum moisture content (OMC)
were determined using standard compaction method and modified method in
accordance with IS:10074:1987 , BIS 270 (Part-VIII)
Calculation
Diameter of mould = 10 cm
Height of mould = 12.7 cm
Volume of mould = 1000 cc
Sample (Kg)
Weight of empty mould + base plate (W1) 5.390
Weight of compacted soil + base plate (W2) 7.453
Bulk unit weight of compacted soil (Y gm/cc) 2.068
Water content (w %) 12.04
Dry unit weight (Yd gm/cc) 1.77
Table 3. Observation And Calculations of Maximum Dry Density Test
Result: Bulk unit weight of compacted soil (Y) = 2.068 gm/cc
Dry unit weight (Yd) =1.77 gm/cc
15

4.2.4. CBR Test
4.2.4.1. Definition
It is the ratio of force per unit area required to penetrate a soil mass with standard
circular piston at the rate of 1.25 mm/min. to that required for the corresponding
penetration of a standard material.
Test Load
C. B. R. = Standard Load
× 100
The same samples were further tested for CBR using Static Compaction with 56 blows
by standard rammer of 2.6 kg. In 1928 California Division of State Highways developed
CBR method for pavement design the majority of design curves developed later are
based on the original curves proposed by O.J. Porter. One of the chief advantages of
this method is the Simplicity of the test procedure.
The CBR tests were conducted by California State Highways Department on existing
pavement surfaces including sub base, sub grade and base course .Based on the
extensive test data collected on pavements, an empirical design chart was prepared
correlating the CBR values and pavement thickness.
Fig 8. CBR Mould
16

Fig 9. CBR Test Apparatus
4.2.4.2. Observations and Calculations
S. No. Penetration (mm) Load (kg)
1 1.25 29.14
2 2.5 40.14
3 3.75 48.12
4 5.0 55.12
5 6.25 62.37
6 7.50 65.53
7 8.62 67.41
Table 4. Observations of CBR Test
17

CALCULATIONS 40.14
CBR at 2.5mm penetration = 1370 × 100
=2.93%
55.12
CBR at 5.0mm penetration = 2055 × 100
=2.68%
So, value of CBR = 2.93%
GRAPH
80
70
60 (55.12)
(kg)
50
40
(40.14)
Lo
ad
Figure Penetartion vs. Load
30
20
10
0
0 2 4 6 8 10
Penetration(mm)
Fig 10. Graph of Penetration and Load by CBR Test
18

CHAPTER- 5
DESIGN APPROACH AND CRITERIA
5.1. DESIGN APPROACH AND CRITERIA
The design of flexible road pavements is generally thought to be a specialist activity
that can only be undertaken by consultants experienced in this type of design. Part of
the reason for this may be that foreign consultants engaged on the design of road
pavements in Nepal have tended to use design standards from their respective
countries, or other international standards with which they are familiar.
However, the design approaches and criteria for a country should be defined on the
basis of local conditions i.e. climatic socio-economic and technological development and
so on. In this way, intensive research activities should have conducted by the concerned
authorities. The flexible pavements has been modeled as a three layer structure and
stresses and strains at critical locations have been computed using the linear elastic
model. To give proper consideration to the aspects of performance, the following three
types of pavement distress resulting from repeated (cyclic) application of traffic loads
are considered:
Vertical compressive strain at the top of the sub-grade which can cause sub-
grade deformation resulting in permanent deformation at the pavement
surface.
Horizontal tensile strain or stress at the bottom of the bituminous layer which
can cause fracture of the bituminous layer.
Pavement deformation within the bituminous layer.
19

Fig11. Structural Elements of Road
The permanent deformation within the bituminous layer can be controlled by meeting
the mix design requirements as per the Standards Specifications for Road and Bridge
Works (Do R, 2001). The thickness of granular and bituminous layers are selected by
using the analytical design approach so that strains at the critical points are within the
allowable limits. For calculating tensile strains at the bottom of the bituminous layer,
the stiffness of dense bituminous macadam (DBM) layer with 60/70 bitumen has been
used in the analysis. The relationships used for allowable vertical sub-grade strain and
allowable tensile stain at the bottom of bituminous layer along with elastic moduli of
different pavement materials and relationships for assessing the elastic moduli of sub-
grade, granular and base layers.
Best on the performance of existing design and using analytical approach, simple
design charts and a catalogue of pavement design have been added for the use of
engineers. The Pavement design are given for sub-grade CBR value ranging from 2
percent to 10 percent and design traffic from 1 msa to 150 msa for an average annual
pavement temperature of 35 0C. The layer thickness obtained from the analysis has
been slightly modified to adapt the designs to stage construction. Using the following
simple input parameters, appropriate design could be chosen for given traffic and sub-
grade soil strength:
a) Design traffic in terms of cumulative number of standard axles
b) CBR values of Sub-grade
20

The primary function of pavement is to distribute the concentrated loads so that the
supporting capacity of the sub-grade soil is not exceeded. With this purpose in view,
the road structure has been composed of a number of layers, properly treated,
compacted and place one above the other. Some of these layers at times may be
combined. In general, the structure of a road will constitute of:
1. The Sub Grade
2. The Sub Base
3. The base
4. Surface course
5.1.1. Sub grade Strength or bearing capacity
It is measured using the CBR test, typically CBR 2-3 for clays and 15% or greater
for sandy soils. Used directly in the empirical design procedure.
5.1.2. Pavement Material Characteristics
Need to know what materials are available. The generally used Type 2.1 for top
150mm with Type 2.3 below. For deep pavements, may also have a deep layer of
CBR15 material
5.1.3. Design Traffic Loading
The Standard Axle loading is defined as an axle with dual tyres loaded to 80kN (8.2
tonne).
Vehicle Type Number of ESAs For Max Legal Loading
2 Axle Rigid 2.2
3 Axle Rigid 2.5
3 Axle Articulated 3.3
4 Axle Rigid 3.6
4 Axle Articulated (Spread Tandem) 4.2
5 Axle Articulated (Spread Tandem) 4.4
Table5. Equivalent Standard Axles
21

5.2. DESIGN WHEEL LOAD
5.2.1. Max. Wheel load - It is used to determine the depth of the pavement
required to ensure that the sub grade soil does not fail.
5.2.2. Contact pressure - It determines the contact area and the contact pressure
between the wheel and the pavement surface. For simplicity elliptical
contact area is consider to be circular.
5.2.3. Axle configuration - the axle configuration is important to know the way in
which the load is applied on the pavement surface.
Fig12. Axle Configuration
5.2.4. Equivalent single wheel load (ESWL)
Fig13. Equivalent Single Wheel Load (ESWL)
22

5.3. PAVEMENT DESIGN
a) General
Considering the sub grade strength, projected traffic and the design life, the flexible
pavement design for low volume PMGSY roads has been carried out as per guidelines
of IRC: 37-2001
b) Pavement Design Approach
Design Life: A design life of 10 years will be considered for the purpose of
pavement design of Flexible pavements.
Design Traffic: The commercial vehicle per day (CVPD) is presented in design.
Determination of pavement thickness from the graph: Thickness of pavement is
determined by first calculating the traffic in terms of MSA and also the CBR of
the soil. Taking reference to both the quantities the pavement thickness and its
composition is determined accordingly.
Flexible Pavement composition: The designed pavement thickness and
composition will be calculated by Pavement design catalog of IRC: 37 – 2001.
Top layer of WBM will be treated with bituminous surface. The details of
pavement design are given above
Embankment Design: As such there is no any place where embankment is .00
m high.
Hence, design of embankment is not carried out.
5.4. IRC METHOD OF DESIGN OF FLEXIBLE PAVEMENTS
(IRC: 37-2012)
5.4.1. IRC:37-1970
Based on California Bearing Ratio (CBR) of sub grade.
Traffic in terms of commercial vehicles (more than 3 tonn laden weight).
5.4.2. IRC:37-1984
• Based on California Bearing Ratio (CBR) of sub grade.
• Design traffic was considered in terms of cumulative number of equivalent standard
axle load of 80 kN in millions of standard axles (msa)
• Design charts were provided for traffic up to 30 msa using an empirical approach.
23
5.4.3. IRC:37-2001

Based on Mechanistic-Empirical method
Pavements were required to be designed for traffic as high as 150 msa.
The limiting rutting is recommended as 20 mm in 20 percent of the length for
design traffic.
5.4.4. IRC:37-2012
Based on Mechanistic-Empirical method
The limiting rutting is recommended as 20 mm in 20 percent of the length for
design traffic up to 30 msa and 10 percent of the length for the design traffic
beyond.
5.4.5. Guidelines for Design by IRC: 37: 2012
5.5. DESIGN TRAFFIC
The recommended method considers design traffic in terms of the cumulative
number of standard axles (80 kN) to be carried by the pavement during the
design life.
Only the number of commercial vehicles having gross vehicle weight of 30 kN
or more and their axle loading is considered for the purpose of design of
pavement.
Assessment of the present day average traffic should be based on seven-day-24-
hour count made in accordance with IRC: 9-1972 "Traffic Census on Non-
Urban Roads".
5.5.2. Design Data
1. According to the test results, the C.B.R. value of the sub grade
soil is found to be =2.93 %
2. Traffic Vehicle per Day is assumed to be 100 CVPD.
3. Traffic growth rate, to be taken as 2%.
4. Vehicle Damage Factor, for plain terrain = 3.5
5. Design Life = 10 Years.
6. Distribution Factor = 0.75
7. Single Lane Road.
24

Fig14. Flexible Pavement Thickness Graph According to CBR
Value
So, the Flexible Pavement thickness according to IRC 37-2012 for 1.05msa and
CBR value upto 3% is 635mm.
25

CHAPTER- 6
FAILURES OF FLEXIBLE PAVEMENT
Different types of failure encountered in flexible pavements are as follow:
1. Alligator cracking or Map cracking (Fatigue)
2. Consolidation of pavement layers (Rutting)
3. Shear failure cracking
4. Longitudinal cracking
5. Frost heaving
6. Lack of binding to the lower course
7. Reflection cracking
8. Formation of waves and corrugation
9. Bleeding
10. Pumping
6.1. ALLIGATOR CRACKING OR MAP CRACKING (Fatigue)
Followings are the primary causes of this type of failure:
Relative movement of pavement layer material
Repeated application of heavy wheel loads
Swelling or shrinkage of sub grade or other layers due to moisture variation
Alligator cracks are also called as map cracking. This is a fatigue failure caused in the
asphalt concrete. A series of interconnected cracks are observed due to such distress.
The tensile stress is maximum at the asphalt surface (base). This is the position where
the cracks are formed, i.e. the area with maximum tensile stress. A parallel of
longitudinal cracks will propagate with time and reaches the surface.
26

Repeated loading and stress concentration will help the individual cracks to get
connected. These will resemble as a chicken wire or similar to the alligator skin. This
is termed as the alligator cracking. It is also known as the crocodile cracking.
These crackings are observed only in areas that have repeated traffic loading. Alligator
cracking is one of the major structural distress. This distress is later accompanied by
rutting.
Causes of Premature Failures
Rutting due to high variation in ambient temperature
Uncontrolled heavy axle loads
Limitation of pavement design procedures to meet local environmental
conditions
6.2. TYPES OF DISTRESSES/FAILURES AND DEFINITIONS
6.2.1. Longitudinal Cracking: Cracks that are approximately parallel to pavement
centerline and are not in the wheel path. Longitudinal cracks are non-load associated
cracks. Location within the lane (wheel path versus non-wheel path) is significant.
Longitudinal cracks in the wheel path are normally rated as Alligator ‘A 'cracking.
Fig15. Longitudinal Cracks
27

6.2.2. Fatigue Cracking: Cracks in asphalt layers that are caused by repeated traffic
loadings. The cracks indicate fatigue failure of the asphalt layer. When cracking is
characterized by interconnected cracks, the cracking pattern resembles that of an
alligator’s skin or chicken wire. Therefore, it is also referred to as alligator cracking.
Fig16. Fatigue Crack
6.2.3. Transverse Cracking: Cracks that are predominately perpendicular to pavement
centerline and are not located over Portland cement concrete joints. Thermal cracking
is typically in this category.
Fig17. Transverse Cracks
28

6.2.4. Reflection Cracking: Cracks in HMA overlay surfaces that occur over joints in
concrete or over cracks in HMA pavements.
Fig18. Reflection Crack
6.2.5. Block Cracking: Pattern of cracks that divides the pavement into approximately
rectangular pieces. Rectangular blocks range in size from approximately 0.1 square yard
to 12 square yards.
Fig19. Block Cracks
29

6.2.6. Edge Cracking: Crescent-shaped cracks or fairly continuous cracks that intersect
the pavement edge and are located within 2 feet of the pavement edge, adjacent to the
unpaved shoulder. Includes longitudinal cracks outside of the wheel path and within 2
feet of the pavement edge .
Fig20. Edge Crack
6.2.7. Rutting: Longitudinal surface depression that develops in the wheel paths of
flexible pavement under traffic. It may have associated transverse displacement.
Fig21. Rutting
6.2.8. Corrugation: Transverse undulations appear at regular intervals due to the
unstable surface course caused by stop-and-go traffic.
30

Fig22. Corrugation
6.2.9. Shoving: A longitudinal displacement of a localized area of the pavement surface.
It is generally caused by braking or accelerating vehicles, and is usually located on hills
or curves, or at intersections. It also may have vertical displacement.
Fig23. Shoving
6.2.10. Depression: Small, localized surface settlement that can cause a rough, even
hazardous ride to motorists.
Fig24. Depressions
31

6.2.11. Overlay Bumps: In newly overlaid pavements, bumps occur where cracks in old
pavements were recently filed. This problem is most prevalent on thin overlays.
Fig25. Overlay Bump
6.2.12. Delamination: Loss of a large area of pavement surface. Usually there is a clear
separation of the pavement surface from the layer below. Slippage cracking may often
occur as a result of poor bonding or adhesion between layers.
Fig26. Declamations
32

6.2.13. Pot Holes: Bowl-shaped holes of various sizes in the pavement surface.
Minimum plan dimension is 150 mm.
Fig27. Pot Holes
6.2.14. Patching: Portion of
pavement removed and replaced or
additional construction
surface, greater than 0.1 sq. meter, that has
been material applied to the pavement after
original
Fig28. Patching
33

6.2.15. Pumping: Seeping or ejection of water and fines from beneath the pavement
through cracks.
Fig29. Pumping
6.2.16. Bleeding/Flushing: Excess bituminous binder occurring on the pavement
surface. May create a shiny, glass-like, reflective surface that may be tacky to the touch
. Usually found in the wheel paths.
Fig30. Bleeding and Flushing
34

CHAPTER- 7
MACHINES
7.1. MACHINERIES USED FOR THE PAVEMENT OF THE
ROAD
1. Back hoe loader
2. Pavers Machine
3. Vibratory Roller
4. Bitumen Sprayer
10.1.1. Back Hoe Loader: A backhoe loader, also called a loader backhoe, digger in
layman's terms, or colloquially shortened to backhoe within the industry, is a heavy
equipment vehicle that consists of a tractor like unit fitted with a loader-style
shovel/bucket on the front and a backhoe on the back. Due to its (relatively) small size
and versatility, backhoe loaders are very common in urban engineering and small
construction projects (such as building a small house, fixing urban roads, etc.) as well
as developing countries. This type of machine is similar to and derived from what is
now known as a TLB (Tractor-Loader-Backhoe), which is to say, an agricultural
tractor fitted with a front loader and rear backhoe attachment.
The true development of the backhoe actually began in 1947 by the inventors that
started the Wain-Roy Corporation of Hubbardston, Massachusetts. In 1947 Wain-Roy
Corporation developed and tested the first actual backhoes. In April 1948 Wain-Roy
Corporation sold the very first all hydraulic backhoes, mounted to a Ford Model 8N
tractor.
Uses:
Backhoe loaders are very common and can be used for a wide variety of tasks:
construction, small demolitions, light transportation of building materials,
powering
35

building equipment, digging holes/excavation, landscaping, breaking asphalt,
and paving roads. Often, the backhoe bucket can also be replaced with powered
attachments such as a breaker, grapple, auger, or a stump grinder. Enhanced
articulation of attachments can be achieved with intermediate attachments such
as the tilt rotator. Many backhoes feature quick coupler (quick-attach)
mounting systems and auxiliary hydraulic circuits for simplified attachment
mounting, increasing the machine's utilization on the job site. Some loader
buckets have a retractable bottom or "clamshell", enabling it to empty its load
more quickly and efficiently. Retractable-bottom loader buckets are also often
used for grading and scraping. The front assembly may be a removable
attachment or permanently mounted.
Because digging while on tires intrinsically causes the machine to rock, and the
swinging weight of the backhoe could cause the vehicle to tip, most backhoe
loaders use hydraulic outriggers or stabilizers at the rear when digging and
lower the loader bucket for additional stability. This means that the bucket must
be raised and the outriggers retracted when the vehicle needs to change
positions, reducing efficiency. For this reason many companies offer miniature
tracked excavators, which sacrifice the loader function and ability to be driven
from site to site, for increased digging efficiency.
Fig31. Back Hoe Loader
36

7.1.2. Paver Machine
I. A paver (paver finisher, asphalt finisher, paving machine) is a piece of
construction equipment used to lay asphalt on roads, bridges, parking lots and
other such places. It lays the asphalt flat and provides minor compaction before
it is compacted by a roller.
Fig32. Paver Machine
7.1.2.1. History
The asphalt paver was developed by Barber Greene Co., that originally
manufactured material handling systems. In 1929 the Chicago Testing
Laboratory approached them to use their material loaders to construct asphalt
roads. This did not result in a partnership but Barber Greene did develop a
machine based on the concrete pavers of the day that mixed and placed the
concrete in a single process. This setup did not prove as effective as desired and
the processes were separated and the modern paver was on its way. In 1933 the
independent float screed was invented and when combined with the tamper bar
provided for uniform material
37

density and thickness. Harry Barber filed for a patent a "Machine for and
process of laying roads" on 10 April 1936 and received patent U.S. Patent
2,138,828 on 6 December 1938. The main features of the paver developed by
Barber Greene Co. have been incorporated into most pavers since, although
improvements have been made to control of the machine.
7.1.2.2. Operation
1. The asphalt is added from a dump truck or a material transfer unit into the
paver's hopper. The conveyor then carries the asphalt from the hopper to the
auger. The auger places a stockpile of material in front of the screed. The screed
takes the stockpile of material and spreads it over the width of the road and
provides initial compaction.
2. The paver should provide a smooth uniform surface behind the screed. In order
to provide a smooth surface a free floating screed is used. It is towed at the end
of a long arm which reduces the base topology effect on the final surface. The
height of the screed is controlled by a number of factors including the attack
angle of the screed, weight and vibration of the screed, the material head and
the towing force.
3. To conform to the elevation changes for the final grade of the road modern
pavers use automatic screed controls, which generally control the screed's angle
of attack from information gathered from a grade sensor. Additional controls
are used to correct the slope, crown or superelevation of the finished pavement.
4. In order to provide a smooth surface the paver should proceed at a constant
speed and have a consistent stockpile of material in front of the screed. Increase
in material stockpile or paver speed will cause the screed to rise resulting in
more asphalt being placed therefore a thicker mat of asphalt and an uneven
final surface.
5. The need for constant speed and material supply is one of the reasons for using
a material transfer unit in combination with a paver. A material transfer unit
allows for constant material feed to the paver without contact, providing a better
end
38

surface. When a dump truck is used to fill the hopper of the paver, it can make
contact with the paver or cause it to change speed and affect the screed height.
10.2. SOME OTHER MACHINES
Fig 33. Vibratory Roller
Fig34. Bitumen Sprayer
39

CHAPTER-8
CONCLUSION
The main observations and conclusions drawn are summarized below:
It can be concluded that there is a need of a connecting the campus buildings
of SMS, Lucknow which serves the way of passage for those belongings to
institute providing the Flexible Pavement and the prosperity of our institute
will increase.
Our project naming “DESIGN AND ANALYSIS OF FLEXIBLE
PAVEMENT” consists of total length 750m and road width 3.7m in SMS,
LUCKNOW. It took about 2 months to complete the project including
surveying, soil testing, estimating and costing etc.
As per the traffic of the road and its loading conditions value of cumulative
number of standard axles (N) is 1.05 msa. Also the value from CBR test is
2.93%. So, the Flexible Pavement thickness according to IRC 37-2012 for
1.05msa and CBR value upto 3% is 635mm. According to which the height of
Sub Grade is 0.335m, Granular Sub Base is 0.225m, Base-coarse Bituminous
Macadam is 0.05m and Surface-coarse Bituminous Macadam is 0.025m.
The final cost for the road construction material will be about Rs 13,06,665
/- . The road will have less maintenance as proper design considerations have
been adopted by efficient practical performance standards and suitable
calculations as per defined in standard IRC codes.
40

REFRENCES
1. IRC 37:2012 - Guidelines for the Design of Flexible
2. IS: 20:2007 Codes for the rural roads & standard designing of a
pavement.
3. Khanna & Justo, Highway Engineering Provisions & general data
obtained for soil tests, designing of flexible pavement & traffic survey
study.
4. B.N Dutta, Cost Estimation, Estimation procedures & format obtained
by this book.
5. K R Arora, Soil Mechanics & Foundation Engineering Soil tests &
their details are obtained.
6. B.C Punmia, Soil Mechanics, Soil tests & their applications are
preferred from this book.
7. www.wikipedia.org
8. www.civil.org
9. www.civilworks.org
10. www.nptel.co.in
41

Design and analysis of flexible pavement

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