Rigid Pavements by Fasih

Presented By:Presented By:

M. Fasih-ur-RehmanM. Fasih-ur-Rehman

Presented To:Presented To:

Dr. Sajjad MaqboolDr. Sajjad Maqbool

Rigid PavementRigid Pavement

Those which are surfaced with Portland Cement Those which are surfaced with Portland Cement Concrete (PCC).Concrete (PCC).

These types of pavements are called “Rigid" These types of pavements are called “Rigid" because they are substantially stiffer than flexible because they are substantially stiffer than flexible pavements due to PCC's high stiffness.pavements due to PCC's high stiffness.

Surfaces of a Typical Rigid PavementSurfaces of a Typical Rigid Pavement

Surface courseSurface course• This is the top layer, which consists of the PCC This is the top layer, which consists of the PCC

slabslab..

Surfaces of a Typical Rigid PavementSurfaces of a Typical Rigid Pavement

Base courseBase course• This is the layer directly below the PCC layer and This is the layer directly below the PCC layer and generally consists of aggregate or stabilized sub-generally consists of aggregate or stabilized sub-grade.grade.

Lean Concrete Base Material

Surfaces of a Typical Rigid PavementSurfaces of a Typical Rigid Pavement::

Sub-base courseSub-base course• The base course is immediately The base course is immediately

beneath the surface course.beneath the surface course.It:It:

• Minimizes the intrusion of fines from the Minimizes the intrusion of fines from the sub-grade into the pavement structure. sub-grade into the pavement structure.

• Improves drainage. Improves drainage. • Minimizes frost action damage.Minimizes frost action damage.• Provides a working platform for Provides a working platform for

construction.construction.

Why Rigid Pavement is Constructed?Why Rigid Pavement is Constructed?

Load distribution Load distribution is on wider area.is on wider area.

So additional So additional base and sub-base and sub-base layers are base layers are not necessarily not necessarily required.required.

Why Rigid Pavement is Why Rigid Pavement is Constructed?Constructed?

Due to higher strength it carries more load Due to higher strength it carries more load and undergoes less wear and tear.and undergoes less wear and tear.

The chemical and mechanical resistance of The chemical and mechanical resistance of rigid pavements is excellent, making them rigid pavements is excellent, making them ideal for high traffic loading and container ideal for high traffic loading and container terminals etc.terminals etc.

Initial cost of rigid pavement is high but its Initial cost of rigid pavement is high but its lesser maintenance cost and long life with lesser maintenance cost and long life with more load carrying capacity make it more load carrying capacity make it economical.economical.

Types of Rigid PavementTypes of Rigid Pavement

Rigid pavements are differentiated into three Rigid pavements are differentiated into three major categories by their means of crack major categories by their means of crack control.control.

• Jointed Plain Concrete Pavement (JPCP)Jointed Plain Concrete Pavement (JPCP)• Jointed Reinforced Concrete Pavement Jointed Reinforced Concrete Pavement

(JRCP)(JRCP)• Continuously Reinforced Concrete Continuously Reinforced Concrete

Pavement (CRCP)Pavement (CRCP)• Fiber Reinforced Concrete PavementFiber Reinforced Concrete Pavement


Jointed Plain Concrete Pavement (JPCP)Jointed Plain Concrete Pavement (JPCP)

• JPCP controls cracks by dividing the pavement up into JPCP controls cracks by dividing the pavement up into individual slabs separated by contraction joints.individual slabs separated by contraction joints.

• Slabs are typically one lane wide and between 3.7 m Slabs are typically one lane wide and between 3.7 m (12 ft.) and 6.1 m (20 ft.) long.(12 ft.) and 6.1 m (20 ft.) long.

• It does not use any reinforcing steel but does use dowel It does not use any reinforcing steel but does use dowel bars and tie bars.bars and tie bars.

Jointed Plain Concrete Pavement (JPCP)Jointed Plain Concrete Pavement (JPCP)

Jointed Plain Concrete Pavement (JPCP)


Jointed Reinforced Concrete Pavement (JRCP)Jointed Reinforced Concrete Pavement (JRCP)

• JRCP uses contraction joints and reinforcing steel to JRCP uses contraction joints and reinforcing steel to control cracking.control cracking.

• Transverse joint spacing is longer than that for JPCP Transverse joint spacing is longer than that for JPCP and typically ranges from about 7.6 m (25 ft.) to 15.2 and typically ranges from about 7.6 m (25 ft.) to 15.2 m (50 ft.).m (50 ft.).

• Temperature and moisture stresses are expected to Temperature and moisture stresses are expected to cause cracking between joints, hence reinforcing steel cause cracking between joints, hence reinforcing steel is used to hold these cracks tightly together.is used to hold these cracks tightly together.

Jointed Reinforced Concrete Pavement Jointed Reinforced Concrete Pavement (JRCP)(JRCP)

Jointed Reinforced Concrete Pavement (JRCP)


Continuously Reinforced Concrete Pavement Continuously Reinforced Concrete Pavement (CRCP)(CRCP)

• CRCP does not require any contraction joints.CRCP does not require any contraction joints.

• Transverse cracks are allowed to form but are held Transverse cracks are allowed to form but are held tightly together with continuous reinforcing steel.tightly together with continuous reinforcing steel.

Continuously Reinforced Concrete Pavement Continuously Reinforced Concrete Pavement (CRCP)(CRCP)

Continuously Reinforced Concrete Pavement (CRCP)


Fiber Reinforced Concrete:Fiber Reinforced Concrete:

• In FRC, the amount and location of reinforcement In FRC, the amount and location of reinforcement is not governed by loading and tensile stresses.is not governed by loading and tensile stresses.

• Fibers are randomly dispersed to increase the Fibers are randomly dispersed to increase the strength of concrete.strength of concrete.

• They may be steel, polypropylene, polyethylene or They may be steel, polypropylene, polyethylene or nylon.nylon.

Steel Fibers

Synthetic Fibers

Joints in Rigid PavementJoints in Rigid Pavement

JointsJoints are purposefully placed discontinuities in are purposefully placed discontinuities in a rigid pavement surface course.a rigid pavement surface course.

Concrete pavements are subjected to volumetric Concrete pavements are subjected to volumetric changes due to temperature changes, shrinkage changes due to temperature changes, shrinkage and change in moisture content.and change in moisture content.

To minimize the affect of these stresses, joints To minimize the affect of these stresses, joints are provided.are provided.

Types of JointsTypes of Joints

The most common types of pavement joints, defined The most common types of pavement joints, defined by their function, areby their function, are

• Contraction JointsContraction Joints• Expansion JointsExpansion Joints• Construction JointsConstruction Joints• Longitudinal JointsLongitudinal Joints• Isolation JointsIsolation Joints


Contraction Joints:Contraction Joints:

• Temperature changes cause contraction in the Temperature changes cause contraction in the concrete which induces tensile stresses and slab concrete which induces tensile stresses and slab cracks.cracks.

• A contraction joint is a sawed, formed, or tooled A contraction joint is a sawed, formed, or tooled groove in a concrete slab that creates a weakened groove in a concrete slab that creates a weakened vertical plane.vertical plane.

Typical Contraction Joint

Contraction JointsContraction Joints

Rigid Pavement Showing Contraction Joints

The middle lane contraction jointwas not sawed resulting in a transverseslab crack. The outer lanes have proper Contraction Joints and therefore, no cracking


Function of Dowel Function of Dowel Bar:Bar:


Skewed Contraction Joint:Skewed Contraction Joint:

• Skewed joints are cut at obtuse angles to the Skewed joints are cut at obtuse angles to the direction of traffic flow to help with load transfer.direction of traffic flow to help with load transfer.

• If the joint is properly skewed, the left wheel of If the joint is properly skewed, the left wheel of each axle will cross onto the leave slab first and each axle will cross onto the leave slab first and only one wheel will cross the joint at a time.only one wheel will cross the joint at a time.

• which results in lower load transfer stresses which results in lower load transfer stresses

Skewed Contraction JointSkewed Contraction Joint


Expansion Joints:Expansion Joints:

• Expansion takes place when the temperature of the Expansion takes place when the temperature of the slab rises above the value when it was laid.slab rises above the value when it was laid.

• Expansion joints are intended to provide space in the Expansion joints are intended to provide space in the pavement for expansion of the slab.pavement for expansion of the slab.

• These are omitted altogether.These are omitted altogether.

Typical Expansion Joint


Construction Joints:Construction Joints:

• A construction joint is between slabs that results A construction joint is between slabs that results when concrete is placed at different times.when concrete is placed at different times.

• These joints can be longitudinal as well as transverseThese joints can be longitudinal as well as transverse..

Construction JointsConstruction Joints

Longitudinal and Transverse Construction Joints


Longitudinal Joints:Longitudinal Joints:

• When the pavement width is more than, say 5m,When the pavement width is more than, say 5m,

• Stresses are produced in longitudinal direction Stresses are produced in longitudinal direction

• It is necessary to provide a longitudinal joint with It is necessary to provide a longitudinal joint with some form of load transferring device.some form of load transferring device.

Typical Longitudinal Joints


Isolation Joints:Isolation Joints:

• An isolation joint is used to lessen An isolation joint is used to lessen compressive stresses that develop between compressive stresses that develop between the pavement and a structure (or another the pavement and a structure (or another existing pavement) existing pavement)

• They are typically filled with a joint filler They are typically filled with a joint filler material to prevent water and dirt infiltration.material to prevent water and dirt infiltration.

Isolation JointsIsolation Joints

Roofing Paper Used for an Isolation JointRoofing Paper Used for an Isolation Joint

Design of Rigid PavementDesign of Rigid Pavement

There are mainly four design techniques for There are mainly four design techniques for rigid pavements, which arerigid pavements, which are

• Indian Design GuidelinesIndian Design Guidelines• Design by Westergaard MethodDesign by Westergaard Method• AASHTO Method of Rigid Pavement AASHTO Method of Rigid Pavement

DesignDesign• UK Design Curve (By Road Note)UK Design Curve (By Road Note)


Indian Design Guidelines:Indian Design Guidelines:

• These guidelines are not used internationally.These guidelines are not used internationally.

• This method is not used world wide and is This method is not used world wide and is practiced only in India.practiced only in India.

Indian DesignGuidelines Charts


Design by Westergaard Method:Design by Westergaard Method: InputsInputs

Wheel LoadWheel Load Heaviest single axle loadHeaviest single axle load Flexural Stress of ConcreteFlexural Stress of Concrete Mod. of Rupture Mod. of Rupture Mod. Of Sub-grade ReactionMod. Of Sub-grade Reaction it is determined by it is determined by

Plat Load Test and is expressed asPlat Load Test and is expressed as

k = p / k = p / δδ

where p = applied pressure to soilwhere p = applied pressure to soil

δδ = is corresponding deflection = is corresponding deflection

Design by Westergaard MethodDesign by Westergaard Method


AASHTO Method of Rigid Pavement Design:AASHTO Method of Rigid Pavement Design: InputsInputs

Calculation of Design Load(W18) for design lifeCalculation of Design Load(W18) for design life Reliability “R” in (%)Reliability “R” in (%) Overall Standard Deviation, SoOverall Standard Deviation, So Design Serviceability Loss (Design Serviceability Loss (▲PSI▲PSI)) Modulus of Sub-grade ReactionModulus of Sub-grade Reaction Modulus of Elasticity of ConcreteModulus of Elasticity of Concrete

After these calculation use the following graphAfter these calculation use the following graph

AASHTO chart for Rigid Pavement

AASHTO chart for Rigid Pavement


UK Design Curve (By Road Note)UK Design Curve (By Road Note)

• After calculation of W18, the design chart for After calculation of W18, the design chart for rigid pavement by Road Note is used to find the rigid pavement by Road Note is used to find the thickness.thickness.

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Rigid Pavements by Fasih