types of pavement structure

8/6/2019 Types of Pavement Structure

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Types of pavementTypes of pavement

structure:structure:Presented by:Presented by:

Hamid AnwarHamid Anwar

Waleed AhmadWaleed Ahmad

Mushtaq Ahmad KhanMushtaq Ahmad Khan


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PAVEMENTPAVEMENT Th

e structure whi

ch

separates the tyres of ve

hicles

The structure w

hich

separates the tyres of ve

hiclesfrom the underlying foundation material is calledfrom the underlying foundation material is called

pavement.pavement.

It consists of superimposed layers of processedIt consists of superimposed layers of processed

materials above the soil submaterials above the soil sub--grade, whose primarygrade, whose primaryfunction to distribute applied load to subfunction to distribute applied load to sub--grade.grade.


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Requirements of a pavementRequirements of a pavement

The pavement should meet the followingThe pavement should meet the following

requirements:requirements:

ufficient thickness to distribute the wheelSufficient thickness to distribute the wheelload stresses to a safe value on the subload stresses to a safe value on the sub--

grade soilgrade soil

Structurally strong to withstand all types ofStructurally strong to withstand all types ofstresses imposed upon itstresses imposed upon it

Adequate coefficient of friction to preventAdequate coefficient of friction to prevent

skidd

ing of ve

hicles.sk

idd

ing of ve

hicles.


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Smooth surface to provide comfort toSmooth surface to provide comfort toroad users even at high speedroad users even at high speed

Produce least noise from movingProduce least noise from moving

vehiclesvehicles Dust proof surface so that traffic safetyDust proof surface so that traffic safetyis not impaired by reducing visibility.is not impaired by reducing visibility.

Imperv

ious surface, so t

hat subImperv

ious surface, so t

hat sub--gradegradesoil is well protectedsoil is well protected

Long design life with low maintenanceLong design life with low maintenancecost.cost.

Requirements of a pavementRequirements of a pavement


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Types of pavementTypes of pavement

structure:structure:

Based on the structureBased on the structurepavements are classified intopavements are classified intotwo behaviour,pavementstwo behaviour,pavements

categoriescategories1.1. Flexible pavementFlexible pavement

2.2. Rigid pavementRigid pavement


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1. Flexible pavement1. Flexible pavement

Those pavement whichhave low orThose pavement whichhave low ornegligible flexural strength and flexible innegligible flexural strength and flexible intheir structure action under the load.their structure action under the load.

It transmit vertical or compressive stressesIt transmit vertical or compressive stresses

to the lower layers by grain to grain transferto the lower layers by grain to grain transferthrough contact points of granularthrough contact points of granularstructure.structure.


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The load spreading ability of top layer dependThe load spreading ability of top layer depend

on the type of material.on the type of material.

Bitumen is one of the best flexible pavementBitumen is one of the best flexible pavementmaterial.material.

The compressive stresses is maximum on theThe compressive stresses is maximum on the

pavement surface under th

e wheel & equal topavement surface under t

he w

heel & equal tocontact pressure. The load distributed to largecontact pressure. The load distributed to large

area at the lower layers and hence stressarea at the lower layers and hence stress

intensity decreases.intensity decreases.


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To take the advantages of the stressTo take the advantages of the stress

distribution characteristics of flexibledistribution characteristics of flexible

pavement, layer system concept waspavement, layer system concept wasdeveloped.developed.

The top layer be the strongest to takeThe top layer be the strongest to take

compressive stresses safely. The lowercompressive stresses safely. The lowerlayers take up only lesser stresses, thereforelayers take up only lesser stresses, therefore

low cost material is used.low cost material is used.


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Typical XTypical X--section of flexiblesection of flexible

pavement :pavement :


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Rigid pavement consists of a concrete slabon shallow granular bed hence also called

concrete pavements. It has sufficient

flexural strength to transmit the wheel load

stresses to a wider area below. A typical

cross section of the rigid pavement is

shown in Fig.

2.Rigid Pavements2.Rigid Pavements


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Compared to flexible pavement, rigid

pavements are placed either directly on the

prepared sub-grade or on a single layer ofgranular or stabilized material. Since there is

only one layer of material between the

concrete and the sub-grade, this layer canbe called as base or sub-base course.


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In rigid pavement, load is distributed

by the slab action, and the pavement

behaves like an elastic plate resting

on a viscous medium.


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Basic Structural ElementsBasic Structural Elements

1. Surface Course1. Surface Course

The surface course is the layerin contact with trafficThe surface course is the layerin contact with trafficloads.loads. It provides characteristics such as friction,It provides characteristics such as friction,smoothness, noise control and drainage.smoothness, noise control and drainage. In addition,In addition,it serves as a waterproofing layer to the underlyingit serves as a waterproofing layer to the underlyingbase, subbase and subgrade.base, subbase and subgrade.

2. Base Course2. Base Course

The base course is immediately beneath the surfaceThe base course is immediately beneath the surfacecourse.course. It provides (1) additional load distribution, (2)It provides (1) additional load distribution, (2)contributes to drainage resistance, (3) uniformcontributes to drainage resistance, (3) uniformsupport to the pavement and (4) a stable platform forsupport to the pavement and (4) a stable platform forconstruction equipment.construction equipment.

3. Subgrade Soil3. Subgrade SoilThe natural ground surface whichis prepared forThe natural ground surface whichis prepared forlying of pavement. The main function of subgardelying of pavement. The main function of subgardesoil is to give adequate support to pavementsoil is to give adequate support to pavementstructure.structure.


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Types ofRigid PavementsTypes ofRigid Pavements

Rigid pavements can be classified into four

Rigid pavements can be classified into fourtypes:types:

Jointed plain concreteJointed plain concrete

pavement (JPCP),pavement (JPCP),

Jointed reinforced concreteJointed reinforced concrete

pavement (JRCP),pavement (JRCP),


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Types ofRigid PavementsTypes ofRigid Pavements

Continuous reinforcedContinuous reinforcedconcrete pavementconcrete pavement

(CRCP),(CRCP),

PrePre--stressed concretestressed concrete

pavement (PCP).pavement (PCP).


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SummarySummary

Pavements form the basic supportingPavements form the basic supporting

structure in highway transportation. Eachstructure in highway transportation. Each

layer of pavement has a multitude oflayer of pavement has a multitude of

functions to perform which has to be dulyfunctions to perform which has to be dulyconsidered during the design process.considered during the design process.

Different types of pavements can beDifferent types of pavements can be

adopted depending upon the trafficadopted depending upon the trafficrequirements. Improper design ofrequirements. Improper design of

pavements leads to early failure ofpavements leads to early failure of

pavements.pavements.


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types of pavement structure

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