PER-Lec-1

Pavement Evaluation and Rehabilitation

Lecture-1

15-08-2015

Dr. Zia-ur-Rehman

Course Outline

This course is intended to assist pavement engineers in

developing the most reliable and cost-effective

rehabilitation alternatives for asphalt pavements. It

addresses the rehabilitation process for asphalt pavements

in a logical sequence including the evaluation of the existing

pavement structural and functional condition, assessment

of needs and assignment of feasible alternatives (from four

categories of reconstruction, restoration, recycling, and

resurfacing), and the selection of the preferred

rehabilitation alternative based on life-cycle costs and other

factors.

2Pavement Evaluation and Rehabilitation

Pavement Evaluation

• Pavement evaluations are conducted to determine

functional and structural conditions of a highway section

either for purposes of routine monitoring or planned

corrective action.

• Functional condition is primarily concerned with the ride

quality or surface texture of a highway section.

• Structural condition is concerned with the structural

capacity of the pavement as measured by deflection, layer

thickness, and material properties.3Pavement Evaluation and Rehabilitation

Pavement Rehabilitation

Pavement Rehabilitation consists of

"structural enhancements that extend the

service life of an existing pavement and/or

improve its load carrying capacity.


Rehabilitation Process

• Pavement data collection

• Project Evaluation

• Select feasible alternatives

–4 R programme-Reconstruction,

Restoration, Recycling, Resurfacing

• Life cycle costs plus Non Monetary factors

• Select preferred alternatives

• Detailed Design

• Construction


Pavement Reconstruction

Pavement Reconstruction is the replacement of the entire

existing pavement structure by the placement of the

equivalent or increased pavement structure. Reconstruction

usually requires the complete removal and replacement of the

existing pavement structure. Reconstruction may utilize

either new or recycled materials incorporated into the

materials used for the reconstruction of the complete

pavement section. Reconstruction is required when a

pavement has either failed or has become functionally

obsolete.


Pavement Restoration

Restoration is a set of one or more activities

that repair existing distress and

significantly increase the serviceability (and

therefore, the remaining service life) of the

pavement, without substantially increasing

the structural capacity of the pavement.


Pavement Recycling

Recycling is the process of removing pavement materials for

reuse in resurfacing or reconstructing a pavement (or

constructing some other pavement).

For asphalt pavements, this process may range from in-place

recycling of the surface layer, to recycling material from all

pavement layers through a hot mix plant.

For concrete pavements, recycling involves removal and

crushing for reuse as aggregate, either in the reconstruction

of the pavement or for surface, base, or subbase layers in

other pavement construction.


Pavement Resurfacing

Resurfacing may be either of the following:

(a) A structural overlay, which significantly extends the

remaining service life by increasing the structural capacity

and serviceability of the pavement, usually in combination

with preoverlay repair and/or recycling. A structural overlay

also corrects any functional deficiencies present.

(b) A functional overlay, which significantly extends the

service life by correcting functional deficiencies, but which

does not significantly increase the structural capacity of the

pavement.


Pavements

Learning Objectives

• Describe the types of (Flexible/Rigid/Composite) pavements

• Identify the role of each pavement layer

• Discuss key issues related to pavement performance

• Describe pavement response to traffic loading and

environmental conditions


Conventional Flexible Pavement


Conventional Flexible Pavement

12

Conventional flexible pavements are layered systems with

better materials on top where the intensity of stress is high

and inferior materials at the bottom where the intensity is

low.

Adherence to this design principle makes possible the use

of local materials and usually results in a most economical

design.

This is particularly true in regions where high-quality

materials are expensive but local materials of inferior

quality are readily available .Pavement Evaluation and Rehabilitation

Full Depth Asphalt Pavement


Full Depth Asphalt Pavement

14

Full-depth asphalt pavements are constructed by placing one or

more layers of HMA directly on the subgrade or improved

subgrade.

This concept was conceived by the Asphalt Institute in 1960 and

is generally considered the most cost-effective and dependable

type of asphalt pavement for heavy traffic.

This type of construction is quite popular in areas where local

materials are not available.

It is more convenient to purchase only one material, i.e., HMA,

rather than several materials from different sources, thus

minimizing the administration and equipment costs.


Role of Pavement Layers

15

HMA Layer

Structural capacity, Friction resistance, Riding quality,

Moisture intrusion

Base course

Structural capacity, High quality aggregate, Resistance to

frost action, Drainage

Sub-base course

Structural capacity, Low to medium quality aggregate,

Drainage

Subgrade soil

Ultimately carries load, Provides pavement thickness


Pavement Performance

16

Functional performance

-Provides users a safe and comfortable ride

-Consists of:

•Ride quality

•Surface friction

•Other factors noise, geometrics

Structural performance

-Ability to withstand traffic and environmental loadings


Pavement Performance


Performance Indicator Functional Structural

Distress X X

Structural response X

Surface friction X

Roughness X

PER-Lec-1

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