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Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
Fayoum University
Cultural Exchange Program between
Egypt and Bulgaria 25-31.05.2014
New Technologies and Material Considerations in Pavement Design
Course Topics
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 PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
3
Types of Pavement Design Approaches
Empirical methods based on Strength test (CBR)
Classification (soil classification)
Regression methods based on Road Tests
Mechanistic-Empirical (M-E) methods Mechanistic model predicts stresses, strains, deflections
Regression models to predict pavement life
New Technologies and Material Considerations in Pavement Design
4
AASHTO Method
The Asphalt Institute Method for Flexible Pavements
Portland Cement Association (PCA) Method for Concrete Pavements
Texas DOT Method
Other methods
Current Design Methods
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
5
AASHTO Road Test (late 1950’s)
New Technologies and Material Considerations in Pavement Design
6
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
7
Current Design Methods, continued…
AASHTO Design Equation:
New Technologies and Material Considerations in Pavement Design
8
Current Design Methods , continued… The current design methods in most countries in the
world have relied mostly on:
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. PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
9
Current Design Methods, continued… Generally,
Empirical approach requires a number of observations to be made in order to ascertain the relationships between input variables and outcomes. It is not necessary to firmly establish the scientific basis for the relationships between variables and outcomes. 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.
New Technologies and Material Considerations in Pavement Design
10
Current Design Methods, continued…
These limitations make the empirical design approach obscure and difficult to apply.
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
11
Mechanistic-Empirical Design Approach
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.
New Technologies and Material Considerations in Pavement Design
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M-E Design Approach
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
13
Pavement Performance Today, pavement performance is largely defined by evaluation in the following categories
Roughness (often called "smoothness")
Surface distress
Structural evaluation
Skid resistance (Safety)
New Technologies and Material Considerations in Pavement Design
14
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
15
Performance Prediction Models
Fatigue Cracking Model
Rutting Model
32
11
ff
tf EfFSFN
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.
5
4
f
vf fN
New Technologies and Material Considerations in Pavement Design
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Fatigue and Rutting Coefficients Used
by Various Agencies
Fatigue Coefficients Rutting Coefficients
No. Procedures (Models) f1 f2 f3 f4 f5
1 Arizona DOT 9.33E-07 3.84 0 (Not Available) (Not Available)
2 Austin Research Engineers (ARE) 9.73E-15 5.16 0 (Not Available) (Not Available)
3 Belgian Road Research Center (BRRC) 4.92E-14 4.76 0 3.05E-09 4.35
4 CHEVRON (Not Available) (Not Available) (Not Available) (Not Available) 1.34E-09 4.484
5 Federal Highway Administration 7.56E-12 4.68 0 (Not Available) (Not Available)
6 Illinois DOT 5.00E-06 3 0 (Not Available) (Not Available)
7 SHELL Research 0.0685 5.671 2.363 6.15E-07 4
8 The Asphalt Institute (AI) 4.32E-03 3.291 0.854 1.37E-09 4.477
9 Transport and Road Research Laboratory 1.66E-10 4.32 0 1.13E-06 3.57
10 U.S. Army Corps of Engineers 497.156 5 2.665 1.81E-15 6.527
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
17
M-E Design Process
Environmental Factors
Axle Loadings
Material Properties
Analysis Pavement Structure
Distress Prediction
New Technologies and Material Considerations in Pavement Design
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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
Mechanistic Models
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
19
H1
H2
H3
P
En , nn
E3, n3
E2, n2
E1 , n1
Layered Elastic Model, Inputs
New Technologies and Material Considerations in Pavement Design
22
Layered Elastic Model, Outputs
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
23
Damage Analysis
For Fatigue
For Rutting
4
1 )(
)(0.1
i iallow
ifuture
futureN
NSDR
14
1 )(
)(
i iallow
ifuture
ruttingN
NSDR
New Technologies and Material Considerations in Pavement Design
24
Environmental Effects
Asphalt Bound Materials
Unbound Materials, Subgrade Soil, Granular Base & Subbase
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). PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
Effective Subgrade Resilient Modulus in AASHTO 1993
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. Mr
Season
Winter
Spring
Summer Fall
Freezing
(Snow)
Raining
Mre = Effective
New Technologies and Material Considerations in Pavement Design
Effective Subgrade Resilient Modulus - Cont’d
Mre is an equivalent modulus that would result in the
same damage of seasonal modulus values.
32.28
f 1018.1u reM
Month Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.
Mr(subgrade),
psi
(uf = relative damage)
15900 27300 38700 50000 900 1620 2340 3060 3780 4500 4500 4500
0.02 0.01 0.00 0.00 16.52 4.22 1.80 0.97 0.59 0.39 0.39 0.39 Relative
Damage (uf)
Example
30.25 fu 11.212
30.25)( fuAverage
32.281018.111.2 reM )log(32.2)1018.1
11.2log(
8 reM
Mre = 2185 psi PROFESSOR M
OSTAFA ABO-H
ASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
Effective Subgrade Resilient Modulus - Cont’d
32.28
f 1018.1u reM (uf = relative damage)
Example
Yu f 56.012
)( Y
uAverage f
32.281018.156.0 reM Mre = 3870 psi
Season Mr uf Period Uf * Period
Fall 5000 0.3 3 0.3*3
Winter 30000 0.005 4 0.005*4
Spring 2000 2.6 2 2.6*2
Summer 6000 0.2 3 0.2*3
New Technologies and Material Considerations in Pavement Design
28
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
29
New Technologies and Material Considerations in Pavement Design
30
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
31
New Technologies and Material Considerations in Pavement Design
32
PROFESSOR MOSTAFA A
BO-HASHEMA
Dr. Mostafa Abo-Hashema 5/28/2014
Advanced Topics in Highway Engineering Fayoum University
New Technologies and Material Considerations in Pavement Design
33
Traffic Data
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
New Technologies and Material Considerations in Pavement Design
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Thank You
PROFESSOR MOSTAFA A
BO-HASHEMA