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CONSTRUCTION OF BITUMINOUS PAVEMENTS AND ESTIMATION OF MATERIALS

Project report submitted to JNTU University in partial fulfillment of the requirements

for the award of the Degree of Bachelor of Technology

in

Civil Engineering

SUBMITTED BY

C.SANDEEP REDDY

P.MAHARSHI

P.VANI

D.HARIKA

UNDER THE GUIDANCE OF

S.Srinivasulu

DEPARTMENT OF CIVIL ENGINEERING

KOMMURI PRATAP REDDY INSTITUTE OF TECHNOLOGY

JNTUH UNIVERSITY, HYDERABAD-500078

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CERTIFICATE

This is to certify that the project report “Construction of

Bituminous Pavements and Estimation of Materials” submitted is

the bonafide work completed in partial fulfillment of the requirements

for the award of the degree “Bachelor Degree in Civil Engineering” by

C. SANDEEP REDDY (10RA1A0107), P. MAHARSHI (10RA1A0126), P. VANI

(10RA1A0127) and D. HARIKA (10RA1A0111).

The results embodied in this report were not submitted to any

other university or institute for the award of any degree or diploma.

Prof. S. Srinivasulu

Project guide

Head of the Department

Department of Civil Engineering

Kommuri Pratap Reddy Institute of Technology

JNTUH University.

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ACKNOWLEDGEMENT

The satisfaction that accompanies the successful completion of any

task would be incomplete without the mention of the people who made it

possible and whose constant guidance and encouragement crown all effort

with success. This acknowledgement transcends the realm of formality when

we express our deep gratitude to all those who helped us for the completion

of this project work.

We wish to express our sincere thanks to our enlightened and learned

guide Mr. Sathish sir, Highway Engineer, NCC limited. We are indebted to him

for his deep involvement, expert guidance, constant inspiration and

encouragement throughout the project. Working under him has been a great

experience and a privilege.

We express our sincere thanks to Mr.Balaji sir, Material Engineer,

Nagarjuna Construction Company Limited for the keen interest in the project

results and his kind help whenever we approached him.

It gives us immense pleasure to record our deep sense of gratitude to

R V S Shiva Prasad Sir, Project incharge, ORR Package-2 ,NCC limited, for

providing us with the required data available in your company.

Finally, we thank all those in the Civil Engineering Department and

friends who have helped us in the course of our project, without which our

project work would not have been complete.

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CONTENTS

CHAPTER 1 INTRODUCTION 1

1.0 INTRODUCTION 2

CHAPTER 2 TYPES OF CONSTRUCTION 3

2.0 INTRODUCTION 3

2.1 INTERFACE TREATMENT 3

2.2 BITUMINOUS SURFACE DRESSING 4

2.3 SEAL COAT 5

2.4 PENETRATION MACADAM 5

2.5 BUILT-UP SPRAY GROUT 6

2.6 PREMIX METHODS 6

2.7 BITUMINOUS MACADAM 6

2.8 BITUMINOUS PREMIXED CARPET 7

2.9 BITUMINOUS CONCRETE 7

2.10 SHEET ASPHALT 7

2.11 MASTIC ASPHALT 8

CHAPTER 3 METHODS OF CONSTRUCTION 9

3.1 HOT-MIX METHOD 9

3.2 COLD-MIX METHOD 9

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CHAPTER 4 CONSTRUCTION STEPS OF BITUMINOUS

PAVEMENTS

4.0 INTRODUCTION 10

4.1 APPLICATION OF TACK COAT 10

4.2 PREPARATION AND PLACING OF PREMIX 10

4.3 ROLLING 11

4.4 QUALITY CONTROL OF BITUMINOUS CONCRETE 11

CONSTRUCTION

4.5 FINISHED SURFACE 12

CHAPTER 5 LAYERS OF FLEXIBLE PAVEMENTS

5.0 INTRODUCTION 13

5.1 SUBGRADE 14

5.2 GRANULAR BASE/SUB-BASE COURSE 15

5.3 WATER BOUND MACADAM 16

5.4 WET MIX MACADAM 16

5.5 BITUMINOUS BINDER COURSE 17

CHAPTER 6 PAVEMENT EXECUTION

6.0 EXECUTION OF SUBGRADE 20

6.1 EXECUTION OF GRANULAR SUB-BASE 21

6.2 EXECUTION OF WET MIX MACADAM 22

6.3 EXECUTION OF DENSE BITUMINOUS MACADAM 23

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6.4 EXECUTION OF BITUMINOUS CONCRETE SURFACE 25

CHAPTER 7 LABORATORY TESTS RESULTS

7.0 ATTERBERG LIMITS 27

7.1 FREE SWELL INDEX 28

7.2 GRAIN SIZE ANALYSIS 29

7.3 MODIFIED PROCTOR COMPACTION TEST 30

7.4 CBR TEST 31

7.5 FIELD DENSITY TEST BY SAND REPLACEMENT METHOD 32

7.6 AGGREGATE IMPACT VALUE TEST 33

7.7 COMPRESSIVE STRENGTH OF CONCRETE CUBES 34

7.8 SUMMARY OF CEMENT TEST RESULTS 35

CHAPTER 8 HOT-MIX PLANT

8.0 INTRODUCTION 36

CHAPTER 9 EQUIPMENTS USED IN HIGHWAY

CONSTRUCTION

9.0 EARTH MOVING EQUIPMENT 37

9.1 AGGREGATES SPREADERS 38

9.2 ROLLERS 38

9.3 NUCLEAR GAUGE 41

9.4 ROAD BROOMS 41

9.5 SPRAYERS OR BINDER DISTRIBUTORS 41

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9.6 PAVER FINISHER 42

CHAPTER 10 ESTIMATION OF MATERIALS 43

CHAPTER 11 CONCLUSIONS 48

CHAPTER 12 REFERENCES 49

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CHAPTER 1

INTRODUCTION

1.0 INTRODUCTION

Bituminous pavements are in common use in India and abroad. It is possible

to construct relatively thin bituminous pavement layers over an existing

pavement. Therefore, these are commonly adopted as wearing course.

Flexible pavement could be strengthened in stages by constructing

bituminous pavement layers one after another in a certain period of time.

There are a wide range of constructing materials (type, size and grading of

aggregates and type and grade of bituminous binder) and bituminous

pavement construction techniques in use. Variations in design and

construction types have given rise to the bituminous paving technology.

It is well realized that the excessive binder content over an optimum value for

a given mix is detrimental to the good performance of the black top

pavements. This is contrary to the role of cement as a binder in the cement

concrete mixes, where the excess of the binder does not decrease the

strength.

Therefore, based on the surface area of the aggregates, and the technique of

construction the optimum binder content may be determined. Another

problem associated with the construction of bituminous pavements is the

control of the proper viscosity of the bituminous-aggregate mixtures during

mixing and compaction operations.

In this country, the bituminous construction is by and large adopted on the

surface coarse. In fact till recent years the bituminous construction as a

wearing course or a surface course was considered as the main treatment.

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Bituminous constructions are also adopted for base and binder courses of

pavements on heavy-traffic roads. Different from the cement concrete

surfacing which would require very high cost of construction and a substantial

curing period before opening the road to traffic, the bituminous surfacing has

a distinct advantage in this respect.

The black top construction is in extensive use in developing nations like, India

where the cement as a construction material is in great demand for large

number of other engineering projects. Also stage development is possible in

the case of bituminous roads, depending on traffic demands.

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CHAPTER 2

TYPES OF CONSTRUCTION

2.0 INTRODUCTION

Number of types and methods are in use for bituminous pavement

construction. It is attempted to broadly classify them here based on the

methods of construction. The following construction techniques are in use:

2.1 INTERFACE TREATMENT

The surface of the existing pavement layer is to be cleaned to remove dust

and dirt and a thin layer of bituminous binder is to be sprayed before the

construction of any type of bituminous layer over this surface. This treatment

with bituminous material is called interface treatment.

The interface treatment may either be a prime coat or a tack coat and in some

cases, the prime coat followed by a tack coat.

(a) Prime coat: Prime coat is the first application of a low viscosity liquid

bituminous material over an existing porous or absorbant pavement surface

like the WBM base course.

The main object of priming is to plug in the capillary voids of the porous

surface and to bond the loose mineral particles on the existing surface, using

a binder of low viscosity which can penetrate into the voids.

The bituminous primer is sprayed uniformly using a mechanical sprayer at a

rate of 7.3 to 14.6 kg per 10 sq.m area, depending on the porosity of the

surface. The primed surface is allowed to cure for atleast 24 hrs, during which

no traffic is allowed.

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(b) Tack coat: Tack coat is the application of bituminous material over an

existing pavement surface which is relatively impervious like an existing

bituminous surface or a cement concrete pavement or a pervious surface like

the WBM which has already been treated by a prime coat.

Tack coat is usually applied by spraying bituminous material of higher

viscosity like the hot bitumen at the rate of 4.9 to 9.8 kg per 10 sq.m area

depending in the type of the surface. However in some special circumstance

a tack coat of bituminous emulsion may also be applied in cold state.

2.2 BITUMINOUS SURFACE DRESSING

Bituminous Surface Dressing (BSD) is provided over an existing pavement to

serve as thin wearing coat. The single coat surface dressing consists of a single

application of bituminous binder material followed by spreading of

aggregate cover and rolling. When the surface dressing is similarly done in

two layers, it is called ‘two coat bituminous surface dressing’.

Where better adhesion is required, aggregates precoated with bituminous

binder are used in lieu of conventional surface dressing and this technique is

called ‘Bituminous Surface Dressing with Precoated Aggregates’. The main

functions of BSD are:

(a) To serve as a thin wearing course of pavement and to protect the base

course.

(b) To water proof the pavement surface and to prevent infiltration of surface

water.

(c) To provide dust-free pavement surface in dry weather and mud-free

pavement in wet weather.

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2.3 SEAL COAT

Seal coat is usually recommended as a top coat over certain bituminous

pavements which are not impervious, such as open graded bituminous

constructions like premixed carpet and grouted macadam. The seal coat is a

very thin surface treatment or a single coat surface dressing which is usually

applied over an existing black top surface. A premixed sand bitumen (hot mix)

seal coat is also commonly used over the premixed carpet.

The main functions of seal coat are:

(a) To seal the surfacing against the ingress of water.

(b) To develop skid resistant texture.

(c) To enliven an existing dry or weathered bituminous surface.

2.4 PENETRATION MACADAM

Bituminous Penetration Macadam or Grouted Macadam is used as a base or

binder course. The coarse aggregates are first spread and well compacted in

dry state and after that hot bituminous binder of relatively high viscosity is

sprayed in fairly large quantity at the top. The bitumen penetrates into the

voids from the surface of the compacted aggregates, thus filling up a part of

the voids and binding some stone aggregates together.

Depending upon the quantity of bitumen spread and the extent of

penetration, it is called ‘full grout’ when bitumen penetrated to the full depth

of compacted aggregates and ‘semi-grout’ when it penetrates upto about half

the depth. Full grout is adopted in regions of heavy rain fall and semi-grout is

adopted in regions of moderate rain fall and traffic.

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2.5 BUILT-UP SPRAY GROUT

Built-up Spray Grout (BSG) consists of two-layers composite construction of

compacted crushed aggregates with application of bituminous binder after

each layer for bonding and finished with key aggregates at the top to provide

a total compacted thickness of 75 mm. This method is commonly used for

strengthening of existing bituminous pavements.

2.6 PREMIX METHODS

In this group of methods the aggregates and the bituminous binder are mixed

thoroughly before spreading and compacting. It is possible to coat each

particle of aggregate with the binder still the quantity of binder used may be

considerably lesser than penetration macadam type construction. In

premixed constructions, the quantity of bitumen used could be precisely

controlled and they offer increased stability of the mix even with lower

bitumen contents.

2.7 BITUMINOUS MACADAM

Bituminous Macadam (BM) or Bitumen Bound Macadam is a premixed

construction method consisting of one or more courses of compacted

crushed aggregates premixed with bituminous binder, laid immediately after

mixing. The BM is laid in compacted thickness of 75 mm or 50 mm and three

different gradations of aggregates have been suggested for each thickness to

provide open graded and semi-dense constructions.BM base course is

considered to be much superior than other types of base course materials

such as WBM with respect to load dispersion characteristics and durability.

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2.8 BITUMINOUS PREMIXED CARPET

Premixed Carpet (PC) consists of coarse aggregates of 12.5 and 10.0 mm sizes,

premixed with bitumen or tar binder are compacted to a thickness of 20 mm

to serve as a surface course of the pavement. The PC consists of all aggregates

passing 20 mm and retained on 6.3 mm sieve. When a fairly well graded

material as per specification is used for the construction of the bituminous

carpet of thickness 20 to 25 mm, the construction method is called Semi-

dense Carpet.

2.9 BITUMINOUS CONCRETE

Bituminous Concrete or Asphalt Concrete (AC) is a dense graded premixed

bituminous mix which is well compacted to form a high quality pavement

surface course. The AC consists of a carefully proportioned mixture of coarse

aggregates, fine aggregates, mineral filler and bitumen and the mix is

designed by an appropriate method such as the Marshall method to fulfil the

requirements of stability, density, flexibility and voids. The thickness of

bituminous concrete surface course layer usually ranges from 40 to 75 mm.

The IRC has provided specification for 40 mm thick AC surface course for

highway pavements.

2.10 SHEET ASPHALT

Sheet asphalt or rolled asphalt is a dense sand-bitumen premix of compacted

thickness 25 mm, used as a wearing course. The sheet asphalt consists of well

graded coarse to fine sand (without coarse aggregates) and a suitable

penetration grade bitumen to form a dense and impervious layer. This is laid

over cement concrete pavement to provide an excellent riding surface. The

sheet asphalt also protects the joints in cement concrete pavements and

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could cause a reduction in warping stresses due to a decrease in the

temperature variations between top and bottom of the concrete slab.

2.11 MASTIC ASPHALT

Mastic asphalt is a mixture of bitumen, fine aggregates and filler in suitable

proportions which yields a voidless and impermeable mass. The mastic

asphalts when cooled results in a hard, stable and durable layer suitable to

withstand heavy traffic. The filler, bitumen binder and aggregate are taken in

suitable proportion and they are heated in sequence, and cooked at a

temperature of 200 to 223 C according to the binder grade, for over 5 hrs in

a special cooker. At a temperature of about 200 C the mastic asphalt has such

a consistency that it can flow. But on cooling to atmospheric temperature, it

hardens to semi-solid or solid state. The mastic asphalt should be spread at a

temperature of about 200 C to a thickness between 2.5 to 5 cm. No rolling is

required.

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CHAPTER 3

METHODS OF CONSTRUCTION

3.0 INTRODUCTION

Premix types of bituminous constructions are generally carried out in the field

using appropriate plants. There are two types of mixing plant and travelling

plant.

The centre mixing plant consists of units for batching different materials,

separate heating units for mixed aggregates and bitumen and a mixing unit of

large capacity.

The aggregates, filler and bitumen are transported to the site of the mixing

plant which is stationed at a suitable location and the bituminous mix is again

transported from the plant to the construction site. Generally there is very

good control on the quality of the mix obtained from the central mixing plant.

The travelling plant is a smaller unit and can be shifted from time to time

along the road side as the bituminous construction progresses.

3.1 HOT-MIX METHOD

In hot mix constructions the heated aggregates are mixed with heated

bitumen in a central or travelling plant.

3.2 COLD-MIX METHOD

In cold mix method, the aggregates at atmospheric temperature are mixed

with bituminous material of low viscosity in cold state or after slight heating.

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CHAPTER 4

CONSTRUCTION STEPS OF BITUMINOUS PAVEMENTS

4.0 INTRODUCTION

The existing surface is prepared by removing the pot holes or ruts if any. The

irregularities are filled in with premix chippings at least a week before laying

surface course. If the existing pavement is extremely wavy, a bituminous

levelling course of adequate thickness is provided to lay a bituminous

concrete surface course on a binder course instead of directly laying it on a

WBM.

4.1 APPLICATION OF TACK COAT

It is desirable to lay AC layer over a bituminous base or binder course.

A tack coat of bitumen is applied at 6.0 to 7.5 kg per 10 sq.m area, this

quantity may be increased to 7.5 to 10 kg for non-bituminous base.

4.2 PREPARATION AND PLACING OF PREMIX

The premix is prepared in a hot mix plant of a required capacity with the

desired quality control. The bitumen may be heated upto 150 – 177 C and the

aggregate temperature should not differ by over 14 C from the binder

temperature. The hot mixed material is collected from the mixer by the

transporters, carried to the location and is spread by a mechanic paver at a

temperature of 121 to 163 C .The camber and the thickness of the layer are

accurately verified. The control of the temperature during the mixing and

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the compaction are of great significance in the strength of the resulting

pavement structure.

4.3 ROLLING

A mix after it is placed on the base course, is thoroughly compacted by rolling

at a speed not more than 5 km per hr. The initial or break down rolling is done

by 8 to 12 tonnes roller and the intermediate rolling is done with a fixed wheel

pneumatic roller of 15 to 30 tonnes having a tyre pressure of 7 kg per sq.cm.

The wheels of the roller are kept damp with water. The number of passes

required depends on the thickness of the layer. In warm weather rolling on

the next day helps to increase the density if the initial rolling was not

adequate. The final rolling or finishing is done by 8 to 12 tonnes tandem roller.

4.4 QUALITY CONTROL OF BITUMINOUS CONCRETE

CONSTRUCTION

The routine checks are carried out at site to ensure the quality of the resulting

pavement mixture and the pavement surface. Periodical checks are made for

(a) Aggregate grading

(b) Grade of bitumen

(c) Temperatures of aggregate

(d) Temperatures of paving mix during mixing and compaction.

Atleast one sample for every 100 tonnes of the mix discharged by the hot mix

plant is collected and tested for above requirements. Marshall tests are also

conducted. For every 100 sq.m of compacted surface, one test of the field

density is conducted to check whether it is at least 95% of the density

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obtained in the laboratory. The variation in thickness allowed is 6 mm per 4.5

m length of construction.

4.5 FINISHED SURFACE

The AC surface be checked by a 3.0 m straight edge. The longitudinal

undulations should not exceed 8.0 mm and the number of undulations higher

than 6.0 mm should not exceed 10 in a length of 300 m. The cross profile

should not have undulation exceeding 4.0 mm.

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CHAPTER 5

LAYERS OF FLEXIBLE PAVEMENT

5.0 INTRODUCTION

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5.1 SUBGRADE

After the vegetation and organic dirt are removed from the earth surface, it

requires mild compaction (two passes of 80 – 100 kN smooth wheeled roller,

or equivalent, as per the recommendations).There should not be any soft spot

present in the subgrade. The figure shows the compaction equipment used in

the field.

Soil is spread in uniformly in layers with thickness not exceeding 200 mm and

is then compacted. Motor grader is used for maintaining a suitable grade

during construction. If the moisture content is low, requisite amount of water

is added uniformly with the help of a sprinkler system. If the roadbed material

is too wet, it should be dried through aeration and exposure to sun.

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5.2 GRANULAR BASE/SUB-BASE COURSE

Construction of granular base or sub-base consists of laying and compacting

suitably selected aggregate material over the formed subgrade. The materials

of construction can be natural sand, moorum, crushed stone, crushed

concrete, brick metal, crushed slag etc. As per IRC 37:2001, the sub-base

material, for bituminous pavement construction, should have CBR value 20%

for traffic up to 2 msa and 30% for traffic more than 2 msa.

Granular Sub-base: The name of this course is Granular Sub-base and is more

popularly known as GSB. The aggregates to be chosen should have 10% fines

value as 50 kN in soaked condition. The materials as per the specified

gradation with requisite water should be spread with the help of a motor

grader. Rolling should be done by a 80 – 100 kN static roller with plain drum,

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or by a 200 – 300 kN pneumatic roller whose speed should not exceed 5 kmph.

The above figure shows the dumping and spreading phase of GSB.

5.3 WATER BOUND MACADAM

Water Bound Macadam (WBM) is constituted with a compacted layer of

clean, crushed aggregates and screening material laid on a properly prepared

subgrade, base or sub-base course. Binding material is used wherever

necessary and water is added for proper compaction. Broken stones, crushed

slag, over burnt bricks, and any other naturally occurring aggregates

conforming to the physical requirement, can be used for WBM construction.

5.4 WET MIX MACADAM

The construction of Wet Mix Macadam (WMM) consists of laying and

compacting clean, crushed, and graded aggregates, premixed with water.

WMM is prepared in a mixing plant, in which aggregates and water with

suitable proportion are mixed together.

The optimum moisture content of the mix is determined in the laboratory.

The aggregates, immediately after mixing, are laid on the surface.

After the completion of the construction, setting time is given, during which

it is desirable that not even construction equipment should pass over the

surface.

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The figure shows the WMM work in the field

5.5 BITUMINOUS BINDER COURSE

The commonly used binder courses include Bituminous Macadam (BM) and

Dense graded Bituminous Macadam (DBM). BM has a high level of voids and

therefore it is pervious to water.

During the summer season, its stiffness becomes too low [60]. Thus,

guidelines restrict that it should be used only for the roads whose design life

is less than 5 msa [89]. DBM can also be used as a base course, or as a profile

corrective course [215].

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The figure shows the laying of DBM layer

Aggregates are mixed according to the specifications and the optimum

bitumen content (OBC) is found out from the Marshall requirement set in the

specification. For some mixes, such as BM, OBC is not determined by

Marshall.

Before laying, the surface should be thoroughly cleaned and any loose

materials removed. This can be done using mechanical brooms or high

pressure air jets.

After laying of bituminous mixes, compaction is immediately done. Vibratory

rollers of 80 – 100 kN dead weight and pneumatic tyred rollers of 120 – 150

kN with nine wheels are generally specified for this compaction. The finish

rolling is done using 60 – 80 kN smooth wheeled tandem rollers [215]. The

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level of compaction should be a specified fraction of the Marshall density

determined in the laboratory.

The figure shows the tandem roller and pneumatic tyre roller

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CHAPTER 6

PAVEMENT EXECUTION

6.0 EXECUTION OF SUBGRADE

The excavation has to be done first and then the soil tests has to be done for

every 10 sq.m. That may be either the grain size analysis test, atterberg limits,

free swell index, modified proctor compaction test, CBR test. All these tests

has to done before the execution of the subgrade layer. After the execution

has done the subgrade layer has to be compacted by using the earthwork

compaction roller. The following figure shows the execution of subgrade

layer.

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6.1 EXECUTION OF GRANULAR SUB BASE

After laying the subgrade layer the granular sub-base layer takes place. Before

laying this layer, the aggregate tests has to be done i.e. the strength of the

aggregate, the hardness, the toughness, durability, shape of aggregates and

adhesion test has to be done and some tests for road aggregates like

aggregate crushing test, abrasion test, impact test, soundness test, shape

test, flakiness and elongation index test and specific gravity and water

absorption tests has to be done. After all these test has passed then the

particular aggregate is suitable for construction purpose, then the GSB layer

has to be layed. After laying the GSB the compaction has to be done by using

compaction rollers. The aggregate size used in this layer is 40 mm size. The

following figure shows the laying of GSB layer.

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6.2 EXECUTION OF WET MIX MACADAM

After laying the GSB layer the WMM layer has to be layed. In this layer the

dust material is used i.e. the size of dust particle is 10 mm in size. The same

tests has to be adopted as mentioned the GSB layer. For express ways two

layers of WMM has to be layed i.e. of size 125 mm of each layer after

compaction. After laying the two layers over WMM layer prime coat is done

and after that wait for 24 hrs to penetrate bitumen of 3 mm inside WMM

layer. The figure shows the WMM layer and over that prime coat is shown.

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6.3 EXECUTION OF DENSE BITUMINOUS MACADAM

Over the WMM layer the DBM layer has to be layed. The material used in

DBM is the bitumen, filler and different sizes of aggregates. Before the

execution some tests has to be done i.e. the penetration test, ductility test,

viscosity test, float test, specific gravity test, softening point test, flash and

fire point test, solubility test and water content test has to be done. After all

these tests has passed then we can approve these material for DBM layer.

The DBM has been prepared in the hot-mix plant as per specifications. The

prepared DBM has been carried to the field and layed over WMM layer and

compacted by using tandem rollers and pneumatic tire rollers. The thickness

of DBM layer would be 65 mm after the compaction.

The following figure shows the execution and compaction of DBM layer

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For paving DBM layer the temperature should be greater than 120 C. The

execution can be done by using a paver which is of 6.25 m width. Before using

the paver first set the grade sensors. After laying DBM layer the temperature

of DBM has been checked and it should not be less than 90 C. Thickness gauge

is used to measure DBM thickness. Over the WMM layer the prime coat is

applied and it the slow setting one. It is spread by a sprayer at a rate of 7.5 to

10 kg/10 sq.m. After 24 hrs if the prime coat is not set then the tack coat is

applied and it is a rapid setting one and it is spread by a sprayer at a rate of

2.5 to 3 kg/10 sq.m.

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The following figure the paver used at NCC

6.4 EXECUTION OF BITUMINOUS CONCRETE SURFACE

It is provided at the top of the pavement surface to

(a) Have adequate skid resistance,

(b) Have a waterproof surface,

(c) Prevent entry of air to the pavement, which causes aging of the bitumen,

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(d) Arrest disintegration of particles from the existing road surface, and

(e) Reduce hazards caused by limited visibility, poor night visibility, and dusty

surroundings, and so on.

The following figure shows the perfect flexible pavement surface

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CHAPTER 7

LABORATORY TEST RESULTS

7.0 ATTERBERG LIMITS

35

7.1 FREE SWELL INDEX

36

7.2 GRAIN SIZE ANALYSIS

37

7.3 MODIFIED PROCTOR COMPACTION TEST

38

7.4 CBR TEST

39

7.5 FIELD DENSITY TEST BY SAND REPLACEMENT METHOD

40

7.6 AGGREGATE IMPACT VALUE TEST

41

7.7 COMPRESSIVE STRENGTH OF CONCRETE CUBES

42

7.8 CEMENT TEST RESULTS

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CHAPTER 8

HOT-MIX PLANT

8.0 INTRODUCTION

The temperature required to start hot-mix plant is between 140 -160 C. The

DBM comes out from hot-mix plant with a temperature of 165 C. There will

be 3 sieves in hot-mix plant and 4 hot bins are present. For 1 batch, 2 tons of

DBM is released from hot-mix plant. 24 tons/dumper is carried out from hot-

mix plant. The process takes place like this:

Different sizes of aggregates will be present in cold bins, Through belts the

aggregates and dust is sent to the drier to dry the materials at 100 C, then the

materials is supplied to the hot-mix plant. There in the hot-mix plant the

aggregates of different sizes will pass through sieve and fall in a hot bins, there

in the hot bins the 1% of filler and 4.5% of bitumen is added to prepare 1 ton

of DBM and thoroughly mixed and then stored for a while and comes out from

a mixer. The following figure shows the HOT-MIX PLANT

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CHAPTER 9

EQUIPMENTS USED IN HIGHWAY COSNTRUCTION

9.0 EARTH MOVING EQUIPMENT

Tractor or crawler is the basic equipment used for earth moving activities, to

which various attachments may be fixed for specific purposes. Bulldozer is

another equipment where a movable steel blade is attached to the front of a

tractor. Bulldozers are used for clearing the way along the construction line

and also for moving earth. Another attachment to tractor is ‘loader’, in which

a bucket is used for picking up, transporting, and depositing soil. ‘Hoe’ is

another type of attachment used for digging pits or trenches. Rotary tiller is

an equipment meant for field pulverization of subgrade soil.

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9.1 AGGREGATE SPREADERS

Aggregates spreaders or gritters are used to ensure uniform spreading of

aggregates over the construction surface. Three types of aggregates

spreaders are there they are:

Truck-mounted spreaders: In a truck-mounted spreaders or a fantail

spreader, the aggregate carrier is hinged to the body of the truck. The

operator can change its slope and also the gate opening to control spread of

aggregates. Vertical fins are provided so as to ensure uniform spread of

aggregates over the pavement width. The uniformity of spread largely

depends on the skill of the operator-cum-driver.

Truck-propelled spreaders: In the truck-propelled spreaders, aggregates are

moved onto the rotating belt, and through an adjustable gate, aggregates are

spread uniformly over the surface. When the truck is empty, the spreader is

disconnected and attached to a loaded truck.

Self-propelled spreaders: Self-propelled spreaders consists of two hoppers,

attached at the front and rear of a pneumatic-tyred tractor. Aggregates are

fed to the hoppers through screw feed and the rate of spread can be

controlled through an adjustable gate.

9.2 ROLLERS

Five types of rollers are described namely the smooth-wheeled rollers,

pneumatic- tyred rollers, sheep foot rollers, grid rollers, and vibratory rollers.

Smooth-wheeled rollers: Smooth-wheeled rollers or drum rollers can

compact all types of soil, expect rocky soil. The disadvantages of a Smooth-

wheeled roller are that (1) the level of compaction is sometimes not

satisfactory, because of its large contact area and consequently low pressure

and (2) the weaker aggregates tend to be crushed during compaction.

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Pneumatic-tyred rollers: In Pneumatic-tyred rollers a number of tyres are

placed close and parallel to each other. This is suitable for coarse grained soils

(with 4-8% passing IS75 micron sieve). Depending on the type of material, a

pneumatic-tyred roller can compact faster and with fewer passes than a

smooth-wheeled roller. Figure shows a pneumatic-tyred roller.

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Sheep foot rollers: The sheep foot roller or padfoot roller has some

protrusions on its drum which penetrate into the soft soil and compact it by

kneading and tamping. The padfoot roller has relatively large footprints. The

weight of the roller can be adjusted by changing the amount of water poured

into the rolling drum. Successive passes of the sheepfoot roller decrease the

depth of penetration of the protrusions and this is known as ‘walk-out’. The

measure of walk-out gives some idea regarding the level of compaction

attained. Blending of materials is assisted by this compaction method, and it

also eases the moisture control.

Grid rollers: In grid rollers, the drum is covered with heavy steel grid. The grid

produces high contact pressure which helps to avoid situations, such as plastic

wave formation due to shear deformation of soil. Grid rollers are suitable for

compaction of granular particles and help in breaking and rearranging the

particles. However, grid rollers cannot work effectively on clayey soil as the

soil gets clogged within the grid.

Vibratory rollers: In these rollers, a vibratory motion along the vertical

direction is induced along with the rolling operation. The amplitude of

vibration is of the order of 1 or 2 mm. These vibratory drums are isolated by

means of shock absorbers from the frame on which the operator sits. This

vibratory effect helps in better compaction, specially that of granular

materials. The extent of compaction caused by the vibratory roller depends

on:

(1) Static weight

(2) Vibratory mass

(3) Frequency and amplitude of vibration

(4) Rolling speed

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9.3 NUCLEAR GAUGE

Nuclear gauge are used for field density measurement. The scatter of gamma

rays and neutrons from the nuclear gauge give a measure of the bulk density

of soil and moisture content respectively. Calibration curves are used where

scatter level, bulk density, and moisture content are plotted for known values.

Nuclear gauges measure the compaction level quickly but adequate

precautions must be taken to avoid radiation hazards.

9.4 ROAD BROOMS

Road brooms are used for resurfacing on the existing surface. The road

brooms are used to remove dirt, mud, dust, and other deleterious particles

from the existing surface, such that the adherence of the surface to be laid

with the existing surface, becomes strong. In the rotary road broom, a circular

broom suspended from a frame rotates in a horizontal plane. The position of

the broom can be adjusted from the control installed in the vehicle on which

it is mounted. The bristles of the broom are made of steel, nylon, or fibres and

sometimes a high-pressure air jet is used to serve the same purpose.

9.5 SPRAYERS OR BINDER DISTRIBUTORS

Sprayers or binder distributors are used when a binder (cold or hot) is

required to be sprayed uniformly. Sprayers can be of hand-spray type or of

vehicle mounted multi-nozzle type. A sprayer can either be self-propelled or

towed. A good sprayer is expected to serve the following purposes:

(a) Uniformity in rate of application of the binder.

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(b) Adjustable application rate depending on the requirement of a particular

type of construction.

(c) The area covered, in which the binder is sprayed, should be in accordance

with the area covered by the aggregate spreader.

Depending on the rate of application of the binder, a sprayer can be

categorized as:

(a) Constant rate of spread distributor

(b) Constant volume distributor

(c) Constant pressure distributor

The components of binder distributors are spray bar, spray jet (slotted jet or

whirling jet), binder pump, air compressor, binder tank, and burners.

9.6 PAVER FINISHER

Paver finishers have the arrangement for multipurpose jobs related to

pavement construction. The main components of the paver finisher are:

(a) A loading hopper and a suitable distribution mechanism

(b) A compaction and vibrating arrangement

(c) A mechanism for the construction of a smooth surface finish, free from

surface blemishes. The following figure shows a paver finisher in operation.

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CHAPTER 10

ESTIMATION OF MATERIALS FOR 1 KM OF PAVEMENT

(1) Width of the pavement = 18.2 m (2) Thickness of DBM = 0.065 m (3) Total quantity of DBM required for 1 km of pavement = 1000*18.2*0.065 = 1183 cu.m

(4) Thickness of the BC layer = 0.050 m (5) Total quantity of BC required for 1 km of pavement = 1000*18.2*0.050 =

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910 cu.m

(6) Thickness of WMM = 0.125 m (7) Total quantity of dust required for 1 km of pavement = 1000*18.2*0.125 = 2275 cu.m (8) Thickness of GSB = 0.200 m (9) Total quantity of GSB required for 1 km of pavement = 1000*18.2*0.200 = 3640 cu.m

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(10) Thickness of sub grade = 0.500 m (11) Total quantity of soil for sub grade required for 1 km of pavement = 1000*18.2*0.500 = 9100 cu.m

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(12) Bitumen required for 1 km = 125 tons (13) Tack coat required for 1 km = 5 tons

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CHAPTER 11 CONCLUSIONS

Based on the above discussion, following conclusions are made: (1) Flexible pavements are good roads but not cheaper roads. (2) These roads should be considered only if sufficient funds are available. (3) The thickness of the pavement should not be compromised. (4) Bitumen is going to more costly in future. (6) So it should be used very judiciously. (7) Modification like CR, EVA and SBS may be used to reduce the susceptibility of the bitumen. (8) So, It will reduce the quantity of bitumen also.

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CHAPTER 12 REFERENCES

(1) S. K. KHANNA and C. E. G. JUSTO, Highway Engineering, New Chand &Bros, 2001. (2) PARTHA CHAKROBORTY and ANIMESH DAS, Principles of Transportation Engineering, Prentice-Hall of India Private Limited, 2003. (3) S. P. BINDRA, Highway Engineering, Dhanpat Rai & Sons Publications, 4th Edition, 1981. (4) Data obtained from Nagarjuna Construction Company Limited. (5) Guidelines for the design of Flexible Pavements, Published by, The Indian Roads Congress, 2007. (6) MICHEAL SARGIOUS, Pavement and Surfacings for Highway, Applied Science Publishers Limited. (7) GEORGE KANELLAIDIS, Aspects of Bituminous Construction, ASCE Journal of Transportation Engineering, November/December 1999, pp 481-485. (8) L. R. KADIYALI, Traffic Engineering and Transport Planning, Khanna Publishers, 2004.

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