1 introduction ( Highway Engineering Dr. Sherif El-Badawy )

1

Mansoura University - Faculty of Engineering – Public Works Engineering Dept.

Highway and Airport Engineering

1. Introduction

Dr. Sherif El-Badawy

Mansoura University

4th Year Civil Eng.


40 أعمال الفصل 110 امتحان نهاية الفصل

------------------------------------- 150 النهاية العظمي

:المدة

أسبوع 14

الدرجات


درجات 10= التمــــــــــــــــارين -1

درجات 10= غيــــاب التمـــارين والمحاضرات -2

درجات10 = امتحـان منتصـف الفصـل الدراسـي -3

درجات 10= والمشروع التقـــــــــــــــــرير -4

__________________________________________

درجة 40= المجمـــــــــــــــــوع

أعمال الفصل درجاتتوزيع


Course Contents

• Material Characterization for Roads

and Airfields

• Structure Design of Pavements

• Geometric Design

»Dr. Sherif El-Badawy

• Airport Engineering

»Dr. Metwally Elskely

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Textbook and References:

“Lecture Notes in Highway and Airport Engineering”, by

Sherif El-badawy

• Additional Reference Books: • "Pavement Analysis and Design," by Yang Huang, Prentice

Hall, 2nd edition, 2004,

• "Pavement Engineering - Principles and Practice" by Rajib

Mallick and Tarek El-Korachi CRC Press, Taylor and Francis

Group, 2009

• Supplemental References: AASHTO Guide for Design of Pavement Structures, 1993

Asphalt Institute Manual (MS-1), "Thickness design of

asphalt pavements for highways and streets," 1981.

2008الكود المصري ألعمال الطرق الحضرية والخلوية


Some Useful Links

• Moodle

• http://mansvu.mans.edu.eg/lms/

• Pavement Interactive • www.pavementinteractive.org

• MEPDG • www.TRB.org/MEPDG



Material Characterization and Structural

Design Course Objective

Ability to Characterize Materials

for Roads and Airfields

Ability to Analyze and Design

Flexible and Rigid Pavements

http://mansvu.mans.edu.eg/lms/

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Structure Design Course Contents

• Pavement types, design factors

• Material characterization

• Subgrade

• Subbase and Base

• Binder

• Hot Mix Asphalt (HMA)

• Traffic loading and analysis

• Pavement performance, distress,

serviceability

• Joints, tie bars, dowel bars in concrete

pavements


Course Contents (Cont’d)

• Design of flexible highway pavements

(Both AASHTO 1993 method and the M-E methods)

• Design of rigid highway pavements


Geometric Design

• Stopping and Passing Sight Distance

• Horizontal Alignment

• Vertical Alignment

• Cross Section Elements

• Intersections

• Interchanges

• Parking


Popular Perception

“Pavements are very simple

engineered systems”

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Harsh Reality

• Materials

• Availability

• Behavior

• Traffic Loads

• Volume

• Magnitude

• Dynamic effects

• Environment

• Temperature

• Moisture

• Freeze/Thaw

• Distresses

• Variety

• Interactions

• Construction

• Rehabilitation

Pavement geometry is very simple,

but everything else is very complex!


Objectives of Pavement Design

To provide a surface that is:

• Strong • Traffic Loads

• Environmental Conditions

• Smooth

• Ride Quality

• Safe • Friction

• Drainage

• Economical • Initial construction cost

• Maintenance cost


Roman Roads

(Macaulay, 1974)

Via Appia, Rome

(NAPA, 2002)

"All

roads

lead to

Rome."


Pavement Structural Types

• Flexible

• Asphalt concrete (AC)

• Rigid

• Portland cement concrete (PCC)

• Composite

• Asphalt + PCC

• Stabilized granular layers

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Flexible Pavement Layers

Surface

Base

Subbase

Subgrade

Very Strong

Durable

Impermeable

Manufactured

Expensive

Strong

Free-Draining

Manufactured

Less Expensive

Moderate Strength

Free-Draining

Natural Material

Inexpensive Weak

Moisture Sensitive

In Situ Soil (Foundation)


Stronger Layers “Shield” Weaker

Materials

(McCarthy, 1998)

Depth Effect


Flexible Highway Pavement

(Haas, Hudson, and Zaniewski, 1994)

(Cairo Alexandria Road)


Flexible Highway Pavement

Types of Flexible Pavements:

• Thin (< ~2” AC) • AC just a wearing surface

• Strength provided primarily by unbound

granular layers

• Thick • AC both a wearing surface and structural

layer

• Additional strength provided by unbound

granular layers

• Full-Depth • AC provides all strength

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Rigid Highway Pavement

(Haas, Hudson, and Zaniewski, 1994)


Rigid Highway Pavement

Types of Rigid Pavements:

• Jointed Plain Concrete Pavement (JPCP)

• Jointed Reinforced Concrete Pavement

(JRCP)

• Continuously Reinforced Concrete

Pavement (CRCP)

• Prestressed Concrete Pavements (PCP)


Types of Rigid Pavements

(Huang, 1993)

(Jointed Plain) (Jointed Reinforced)

(Continuously Reinforced) (Prestressed)

(4.5-9 m) (9-30 m)

(90-215 m)


Composite Pavements

(Huang, 1993)

Overlay Sandwich

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Flexible vs. Rigid Pavements

• Load distribution

• Initial cost

• Durability


Load Distribution

• Layered system

• All layers carry part of load

Subgrade

PCC Slab

• Slab action

• Slab carries most load

Subgrade

AC

Base


Initial Cost

• Flexible pavement has lower initial cost

• But may not have lower life-cycle cost


Durability

• Flexible pavement is less durable than rigid

pavement

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Function of Base/Subbase

• Flexible Pavement

• Structural support

• Drainage

• Control of frost effect

• Reduce effect of volume

change of subgrade

• Rigid Pavement

• Prevent pumping

• Drainage

• Control frost effect

• Reduce effect of

volume change of

subgrade

• Construction platform


Fatigue Cracking

Thermal Cracking

Rutting

Structural Distresses: Flexible

Pavement

Mansoura-Gamsa

KSA-Katar


Distresses vs. Failure

When a distress or a

combination of distresses

reaches a certain unacceptable

level it is considered failure


Types of Distresses

Flexible Pavement

• Rutting

• Alligator Fatigue cracking (bottom-up)

• Longitudinal Fatigue cracking (top-down)

• Thermal cracking

• Roughness

• Bleeding

• Etc.

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Structural Distresses: Rigid

Faulting (JPCP)

Transverse Cracking

(JPCP)

Punchouts (CRCP)


Types of Distresses

Rigid Pavement

• Cracking

• Faulting

• Pumping

• Blow-up

• Scaling

• Spalling

• Etc.


Pavement Design Methodologies

• Experience

• Empirical • Statistical models from road tests

• Mechanistic-Empirical • Calculation of pavement

stresses/strains/deformations

• Empirical pavement performance models

• Mechanistic • Calculation of pavement

stresses/strains/deformations

• Mechanics-based pavement performance models


Critical Response Values

et ec

et ec

et at surface + bottom of all bound layers (cracking)

ec at mid-thickness of all layers + top of subgrade (rutting)

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MechanisticMechanistic--Empirical Performance Empirical Performance

Prediction for PavementsPrediction for Pavements

DAMAGE

Distress

Time/

Traffic

OR

Strain

Time/

Traffic

EmpiricalMechanistic


Major Research Projects

• AASHO Road Test

• Strategic Highway Research Program

(SHRP)

• Mechanistic-Empirical Pavement Design

Guide (MEPDG) –DARWin-ME


AASHO Road Test (Late 1950’s)


Layout of AASHO Road Test

OTTAWA

Loop 1 Loop 2

Loop 3 Loop 4 Loop 5 Loop 6

2

3

178

7

1

N

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Loop 5 Layout

Flexible Test Tangent

Rigid Test Tangent

Prestressed

Concrete

Bridge

Steel

I-Beam

Bridge

Turnabout


AASHO Road Test Major Findings

• Concept of Serviceability

• Effect of pavement thickness on performance

• AASHTO 1993 Pavement Design Guide


Serviceability Vs. Time

• Not easy to predict pavement life Time (years)

Serv

iceab

ilit

y

Overdesign

Correct Design

Underdesign

Design Life

Terminal Serviceability


1993 Version

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Limitations of AASHO Road Test

• Specific climate, subgrade,

materials

• Short performance period (low

traffic level)


Higher Traffic Volumes

Data Data

LimitsLimits

(AASHO (AASHO

Road Road

Test)Test)

CurrentCurrent

DesignsDesigns

AXLE LOAD REPETITIONS

PA

VE

ME

NT

TH

ICK

NE

SS

Projection AProjection A

ProjectionProjection BB

Pro

ject

ion

Pro

ject

ion

CC

0 > 100 Million2


SHRP

• 5-year program (1987-1993)

• $150 million on highway research

• Asphalt ($50 million)

• Concrete and construction

• Highway operation

• Long-term pavement performance


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M-E Pavement Design Guide

• The M-E Design Guide is a Design Process which includes a lot of new features: • Analysis of New and Rehabilitated HMA and PCC

Pavements

• Traffic (Load Spectra instead of ESALs).

• Climate (EICM).

• Advanced Material Characterization (Three Levels).

• Sublayering to capture HMA aging and Unbound layer moisture change.

• Linear Elastic and Finite element analysis.

• M-E Distress Models (Based on Damage Accumulation).

• Reliability Analysis

• User friendly Design software provided with the guide.


Pavements do not

last forever

Pavements are Designed

to Fail !! (in a predictable way)


Factors Affecting Pavement

Performance



Performance

• Traffic

• Soil and pavement materials

• Environment

• Construction and maintenance

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Traffic

Traffic has a major effect on pavement performance

Traffic volume

Traffic load

Tire pressure

Rate of applying load (Speed)



Heavier loads have worse effect


Larger tire pressure is

more harmful to pavement

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Parked cars have

larger effect


Wheel load

Fatigue Cracking


Soil

Base

HMA Surface

Wheel load

Permanent Deformation



Performance

• Traffic


• Environment


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Wheel Load

Hot-mix asphalt

Aggregate Base

Natural soil

Material Quality


Environmental Factors

• Moisture

• Temperature

• Aging



Performance

• Traffic

• Soil and pavement

materials

• Environment

• Construction and

maintenance



Performance

• Traffic


• Environment


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• Construction and

maintenance practice largely

affects performance

Construction and maintenance


Construction

Mansoura University - Faculty of Engineering – Public Works Engineering Dept. Mansoura University - Faculty of Engineering – Public Works Engineering Dept.

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Tire Pressure, Contact Pressure &

Contact Area


Tire Pressure & Contact Pressure

• Contact pressure is not constant

throughout the contact area

• For simplicity we usually assume:

• Constant contact pressure

• Contact pressure (pc) = Tire pressure (pt) = p


Contact Area

• Assuming circular contact area (A) with a

radius (a)

A = Load (P) / Pressure (p)

pPAa .//. a


Effect of Changing Tire Pressure

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Effect of Changing Load

p


Comments on Tire Pressure & Loads

• Changing tire pressure affects upper layers

• Changing load affects deeper layers

• Required quality of surface is mostly

determined by tire pressure

• Required pavement thickness is mostly

determined by load magnitude

1 introduction ( Highway Engineering Dr. Sherif El-Badawy )

Engineering

Transcript of 1 introduction ( Highway Engineering Dr. Sherif El-Badawy )