rigid pavement structure and distresses notes

Structure and distresses of rigid pavements

Atul Narayan, S. P.

IIT Madras

September 13, 2015

Outline

Introduction

Structure

Distresses

Rigid Pavement Types

Subordinate learning objectives

▸ To analyze the stress-strain distribution in pavements for givenloading conditions.

▸ To estimate pavement distresses based on stresses andstrains in pavement structure.

▸ To explain the effect of mechanical properties on pavementbehavior and performance.

▸ To analyze the stresses and distresses caused by vehicleloading.

▸ To estimate the expected volume of traffic in design life.

Outline

Introduction

Structure

Distresses


General Structure

Source:www.mto.gov.on.ca

▸ A rigid pavement mainly consists of portland cement concrete(PCC) slabs.

▸ Sometimes a base layer (cement-treated base or granularbase) may be used underneath the slab.

Components of Rigid Pavements

▸ Joints:▸ Longitudinal joints - separates pavement slabs in the

transverse direction▸ Transverse joints

▸ Expansion joints - provided to give room for concrete expansion▸ Contraction joints - provided to reduce stresses due to

contraction▸ Construction joints

▸ Reinforcements - provided to bear tensile stresses due tocontraction

▸ Tie bars - provided to hold slabs across longitudinal jointtogether

▸ Dowel bars - provided to transfer load across tranverse joints

Outline

Introduction

Structure

Distresses


Pumping

▸ It is the loss of subgrade material from underneath the slab.▸ It reduces support for the slab and in turn lead to other

distresses like linear cracking, corner breaks, edge punchoutand so on.

Source:pavementinteractive.org

Pumping (cont.)


Corner break

▸ Caused by a combination of fatigue and pumping


Edge punchout▸ Caused by a combination of fatigue and pumping


Blowup

▸ It is caused by inadequacy of expansion joints.


Faulting

▸ Mainly caused by pumping and the lack of support for the slab


Spalling▸ It is the loss of concrete material by chipping, breaking,

cracking, etc.▸ It is caused by excessive stresses at joints and cracks.


Linear/Longitudinal Cracking

▸ It is caused by a combination of different phenomena - trafficloading, curling, warping, etc.


Outline

Introduction

Structure

Distresses


Types of Rigid Pavements

▸ Jointed Plain Concrete Pavement (JPCP)

▸ Jointed Reinforced Concrete Pavement (JRCP)

▸ Continuous Reinforced Concrete Pavement (CRCP)

▸ Prestressed Concrete Pavement (PCP)

Types of Rigid Pavements (cont.)

Source: Huang (1993)

Jointed Plain Concrete Pavements

▸ It is used when thermal expansion/contraction is notsignificant.

▸ Dowel bars may or may not be provided▸ In case of undoweled slabs load transfer at the joint is through

aggregate interlock.▸ It needs closer joint spacing because of lack of reinforcement

and for aggregate interlock.▸ It is more susceptible to pumping, faulting and corner

breaking.

Jointed Reinforced Concrete Pavement

▸ It is the most common type of concrete pavement▸ Reinforcement is provided for concrete expansion/contraction.▸ Joint spacing can be higher because of the presence of

reinforcements.▸ Dowel bars are provided for transferring load amongst

adjoining slabs.▸ It is more susceptible to pumping and faulting type of failure.

Continuous Reinforced Concrete Pavement

▸ Constructed without transverse joints▸ Joints are viewed as the weekest part of concrete slab.▸ Thermal expansion/contraction stresses are relieved by

cracking of concrete slab.▸ Reinforcement is so provided as to limit the width of cracks

while increasing their number.▸ This type of pavement is more susceptible to edge punchout.

Prestressed Concrete Pavements

▸ Prestressing is used to increase the structural capacity of thepavements.

▸ PCPs require fewer transverse joints.▸ Thickness can be reduced because of prestressing.▸ PCPs are more commonly used as airport pavements.

rigid pavement structure and distresses notes

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