Dr. Mostafa Abo-Hashema
5/28/2014
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25-31.05.2014
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Egypt and Bulgaria
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Cultural Exchange Program between
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Fayoum University
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New Technologies and Material Considerations in Pavement Design
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Course Topics
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1. Introduction
2. Stress-Strain Analysis of Flexible
Pavements (Software)
3. Material Characterization for Pavement
Analysis and Design
4. Pavement Design (State-of-the-Art)
5. Asphalt Institute Methods
6. Design for Stage Construction
7. Introduction to LTPP
Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
Empirical methods based on
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Types of Pavement Design Approaches
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New Technologies and Material Considerations in Pavement Design
Strength test (CBR)
Classification (soil classification)
Regression methods based on Road Tests
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Mechanistic-Empirical (M-E) methods
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Mechanistic model predicts stresses,
strains, deflections
Regression models to predict pavement life
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New Technologies and Material Considerations in Pavement Design
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Current Design Methods
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AASHTO Method
The Asphalt Institute Method for
Flexible Pavements
Portland Cement Association (PCA)
Method for Concrete Pavements
Texas DOT Method
Other methods
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
New Technologies and Material Considerations in Pavement Design
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AASHTO Road Test (late 1950’s)
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New Technologies and Material Considerations in Pavement Design
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
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AASHTO Design Equation:
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Current Design Methods, continued…
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New Technologies and Material Considerations in Pavement Design
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New Technologies and Material Considerations in Pavement Design
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Current Design Methods , continued…
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The current design methods in most countries in the
world have relied mostly on:
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Empirical correlations with past performance,
Index-value-based characterization of material
properties such as the layer coefficient,
R-value or the California Bearing Ratio (CBR-value),
Engineering judgment for design strategy selection.
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
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Current Design Methods, continued…
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New Technologies and Material Considerations in Pavement Design
Generally,
Empirical approach requires a number of observations
to be made in order to ascertain the relationships
between input variables and outcomes.
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It is not necessary to firmly establish the scientific
basis for the relationships between variables and
outcomes.
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It is not prudent to use empirically derived
relationships to describe phenomena that occur outside
the range of the original data used to develop the
relationship.
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New Technologies and Material Considerations in Pavement Design
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Current Design Methods, continued…
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These limitations make the empirical
design approach obscure and difficult
to apply.
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
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Mechanistic-Empirical Design Approach
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New Technologies and Material Considerations in Pavement Design
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A M–E design method for a flexible
pavement means application of the
principles of engineering mechanics to
evaluate the response of pavement
structures to traffic loading and much
improved design methods to carry out
distress prediction or how performance
changes with time.
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New Technologies and Material Considerations in Pavement Design
PR
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M-E Design Approach
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
New Technologies and Material Considerations in Pavement Design
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Pavement Performance
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Roughness (often called
"smoothness")
Surface distress
Structural evaluation
Skid resistance (Safety)
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Today, pavement performance is largely defined
by evaluation in the following categories
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New Technologies and Material Considerations in Pavement Design
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
New Technologies and Material Considerations in Pavement Design

N f  FSF f1  t 
 f2
E1  f
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Fatigue Cracking Model
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Performance Prediction Models
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The factor f1 for actual pavements should be much greater than that for laboratory
specimens due to the fact that wheel loads on actual pavements are not applied at
the same location and there are longer rest periods between load applications, both
of which increase the fatigue life.
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Rutting Model
N f  f 4  v 
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 f5
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New Technologies and Material Considerations in Pavement Design
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Fatigue Coefficients
Rutting Coefficients
Procedures (Models)
f1
f2
f3
f4
Arizona DOT
Austin Research Engineers (ARE)
Belgian Road Research Center (BRRC)
CHEVRON (Not Available)
Federal Highway Administration
Illinois DOT
SHELL Research
The Asphalt Institute (AI)
Transport and Road Research Laboratory
U.S. Army Corps of Engineers
9.33E-07
9.73E-15
4.92E-14
3.84
5.16
4.76
0
0
0
(Not Available) (Not Available)
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No.
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Fatigue and Rutting Coefficients Used
by Various Agencies
(Not Available) (Not Available)
(Not Available)
7.56E-12
5.00E-06
0.0685
4.32E-03
1.66E-10
497.156
0
0
2.363
0.854
0
2.665
4.68
3
5.671
3.291
4.32
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f5
(Not Available) (Not Available)
3.05E-09
1.34E-09
4.35
4.484
(Not Available) (Not Available)
(Not Available) (Not Available)
6.15E-07
1.37E-09
1.13E-06
1.81E-15
4
4.477
3.57
6.527
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
New Technologies and Material Considerations in Pavement Design
Material
Properties
Environmental
Factors
Analysis
Pavement
Structure
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Axle Loadings
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M-E Design Process
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Distress
Prediction
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New Technologies and Material Considerations in Pavement Design
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Mechanistic Models
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Flexible Pavement Response
Two-Dimensional Layered Elastic Model
Example of Computer Programs:ELSYM5,
KENLAYER, WESLEA, CHEVRON, JULEA, and
BISAR
Three-Dimensional Finite Elements Model
Example: EverFlex Program
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
New Technologies and Material Considerations in Pavement Design
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
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Layered Elastic Model, Inputs
H1
H2
E1 , n 1
H3
E2 , n 2

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En , n n
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E3 , n 3
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New Technologies and Material Considerations in Pavement Design
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Layered Elastic Model, Outputs
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
New Technologies and Material Considerations in Pavement Design
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Damage Analysis
For Fatigue
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N ( future)i
i 1
N ( allow)i
SDR future  
 1.0
N ( future)i
i 1
N ( allow)i
1
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SDRrutting  
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For Rutting
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New Technologies and Material Considerations in Pavement Design
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Environmental Effects
Asphalt Bound Materials
Unbound Materials, Subgrade Soil,
Granular Base & Subbase
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Temperature and Moisture
The effect on Elastic Modulus value of an unbound layer
may be represented by a multiplying factor, called Seasonal
Adjustment Factor (SAF).
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
New Technologies and Material Considerations in Pavement Design
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Resilient Modulus (Mr) for subgrade is the main
factor in pavement design. It changes with
surrounding environment changes such as moisture
and temperature. It is important to address the
seasonal moduli in the design process.
Winter
Fall
Mre = Effective
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Summer
Freezing
(Snow)
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Mr
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Effective Subgrade Resilient Modulus
in AASHTO 1993
Spring
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Raining
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Season
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New Technologies and Material Considerations in Pavement Design
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Effective Subgrade Resilient Modulus - Cont’d
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Mre is an equivalent modulus that would result in the
same damage of seasonal modulus values.
u f  1.18 108 M re2.32
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(uf = relative damage)
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Example
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Month
Jan.
Feb.
Mar.
Apr.
May
Mr(subgrade),
15900 27300 38700 50000
psi
Relative
Damage (uf)
0.02 0.01
u
f
June
900 1620
0.00 0.00 16.52 4.22
 25.30
2.11  1.18 108 M re2.32
Advanced Topics in Highway Engineering
July
2340
Nov. Dec.
3060
4500 4500
1.80 0.97
Average(u f ) 
log(
Aug. Sept. Oct.
3780
4500
0.59 0.39
0.39 0.39
25.30
 2.11
12
2.11
)  2.32 log( M re ) Mre = 2185 psi
1.18 108
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
New Technologies and Material Considerations in Pavement Design
u f  1.18 108 M re2.32
(uf = relative damage)
Example
Mr
uf
Period
Fall
5000
0.3
3
Winter
30000
0.005
4
Spring
2000
2.6
2
Summer
6000
0.2
3
f
Y
Average(u f ) 
0.005*4
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2.6*2
0.2*3
Y
 0.56
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Mre = 3870 psi
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0.56  1.18 108 M re2.32
0.3*3
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u
Uf * Period
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Season
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Effective Subgrade Resilient Modulus - Cont’d
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New Technologies and Material Considerations in Pavement Design
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
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New Technologies and Material Considerations in Pavement Design
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New Technologies and Material Considerations in Pavement Design
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
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New Technologies and Material Considerations in Pavement Design
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New Technologies and Material Considerations in Pavement Design
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Advanced Topics in Highway Engineering
Fayoum University
Dr. Mostafa Abo-Hashema
5/28/2014
New Technologies and Material Considerations in Pavement Design
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Traffic Data
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No more ESAL’s!
Traffic input will be number of axles by
type and weight
Same type and quality of raw traffic
data currently used to compute ESAL’s
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T h a n k Y ou
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Advanced Topics in Highway Engineering
Fayoum University