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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