Flexible Pavement Materials Characterization for the 2002 Pavement Design Guide Ramon Bonaquist, Ph.D., P.E. Chief Operating Officer Advanced Asphalt Technologies, LLC New Jersey Pavement Technology Workshop February 25, 2003
Flexible Pavement Materials Characterization for the 2002 Pavement Design Guide
Ramon Bonaquist, Ph.D., P.E.Chief Operating Officer
Advanced Asphalt Technologies, LLC
New Jersey PavementTechnology Workshop
February 25, 2003
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Acknowledgements
• NCHRP Project 1-37A– Dr. Amir Hanna– Project Panel
• ERES Consultants– Prime Contractor
• Professor Matthew W. Witczak– Flexible Pavement Team Leader
• Members of the Flexible Pavement Team
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Outline
• Overview of 2002 Flexible Pavement Design Process
• Importance of Material Characterization• Hierarchical Approach for Design Inputs• Flexible Pavement Materials
Characterization– Asphalt Concrete– Subgrade and Unbound Base/Subbases
• Summarize
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Design ProcessFoundation
AnalysisClimate Material
PropertiesTraffic Analysis
ModifyStrategy
InputsAnalysis
No
Trial Design Strategy
Pavement Response Model
MeetPerformance
Criteria?Distress Prediction Models
ConstructabilityIssues
Viable Alternatives Life Cycle CostAnalysis
Select Strategy
Yes
DamageAccumulation
Strategy Selection
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Distresses
FatigueCracking
Thermal Cracking
Longitudinal Cracking
IRI
Rutting
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Damage
TIME
Criteria
TIME
FATIGUECRACKING
RUTDEPTH Criteria
DesignPeriod
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Materials in Design ProcessFoundation
AnalysisClimate Material
PropertiesTraffic Analysis
ModifyStrategy
InputsAnalysis
No
Trial Design Strategy
Pavement Response Model
MeetPerformance
Criteria?Distress Prediction Models
ConstructabilityIssues
Viable Alternatives Life Cycle CostAnalysis
Select Strategy
Yes
DamageAccumulation
Strategy Selection
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Pavement Response Model
• Multilayer Elastic Solution– JULEA
• Material Properties– Modulus– Poisson’s Ratio
εt
ε
δ
C
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tε
tε
3f32f21
kk
t1ff E
11kNββ
εβ
=
From LayeredElastic Analysis
Field Calibration Factors
Fatigue Cracking
Modified Shell Fatigue Equation
Asphalt Modulus
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Hierarchical Design Inputs
PoorDefaults, Judgement3
FairRegression equations, Regional values
2
GoodProject/Segment Specific Measurements
1
Knowledge of Input Parameter
Determination of Input Values
Input Level
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New Asphalt Concrete
• Modulus Mastercurve– Structural Response– Rutting and Fatigue
• Low Temperature Creep Compliance and Strength– Thermal Cracking Analysis
• Poisson’s Ratio Predicted From Modulus
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Mastercurve
100
1,000
10,000
100,000
-6 -4 -2 0 2 4 6
Log Frequency (Hz)
E*
MPa
-9°C4.4 °C21.1 °C37.86C54.4°C
Reference Temperature 21.1 °C
100
1,000
10,000
100,000
-6 -4 -2 0 2 4 6
Log Reduced Frequency (Hz)
E*
MPa
-9°C4.4 °C21.1 °C37.86C54.4°CMaster Curve
-6-4-20246
-20 0 20 40 60Temperature, °C
log
a(T)
)(log)log()log( Taffr −=
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Compliance
1.E-07
1.E-06
1.E-05
1.E-04
1.E+00 1.E+02 1.E+04 1.E+06 1.E+08 1.E+10
Loading Time, s
D(t
), 1/
psi
3214-4D(t)^
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New Asphalt Concrete
Input Level Property Characterization Method
Modulus Dynamic Modulus |E*| Test ASTM D3496Creep/Strength Indirect Tensile Creep/Strength AASHTO TP9Modulus Predicted From Volumetrics and Binder PropertiesCreep/Strength Extrapolated From limited Creep/Strength TestsModulus Predicted From Volumetrics and Binder GradeCreep/Strength Predicted From Binder Grade
1
2
3
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Dynamic Modulus TestLevel 1
σc
∆σ
StressStrain
Time
Phase Lag
*E σε
=(ASTM D3496, NCHRP 9-19)
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Witczak Predictive EquationLevels 2 and 3
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Witczak Predictive Equation
0.1
1
10
100
0.1 1 10 100
Measured E (10^5 psi)
Pred
icte
d E
(10^
5 ps
i)
new database
original database
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Creep and StrengthLevel 1
AASHTO TP9
1.E-07
1.E-06
1.E-05
1.E-04
1.E+00 1.E+02 1.E+04 1.E+06 1.E+08 1.E+10
Loading Time, s
D(t)
, 1/p
si
3214-4D(t)^
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Creep and StrengthLevels 2 and 3
m
TTC r
tDDtD
+= − )(10 210
)(
Function of Material Characteristics
D(t) = Compliancet = timeT = TemperatureTr = Reference Temperature
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Existing Asphalt Concrete
• Damaged Modulus– Structural Response– Rutting and Fatigue
• Poisson’s Ratio Predicted From Modulus
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Damaged Modulus Mastercurve
Damaged Modulus Mastercurves
100
1000
10000
100000
1000000
10000000
1E-08 0.000001 0.0001 0.01 1 100 10000 1000000 1E+08
Reduced Time
Mod
ulus
(psi
)
0.000.200.501.001.502.003.005.0010.0020.00
Fatigue Damage
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Existing Asphalt Concrete
Input Level Modulus Characterization Method
Damaged Backcalculated from NDTUndamaged Predicted From Volumetrics & Binder Properties From CoresDamaged From Extent of Fatigue CrackingUndamaged Predicted From Volumetrics & Binder Properties From CoresModulus From Condition RatingUndamaged Predicted From Volumetrics and Binder Grade
1
2
3
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Existing Asphalt ConcreteLevel 1
Damaged Modulus Mastercurves
100
1000
10000
100000
1000000
10000000
1E-08 0.000001 0.0001 0.01 1 100 10000 1000000 1E+08
Reduced Time
Mod
ulus
(psi
)
0.000.200.501.001.502.003.005.0010.0020.00
Fatigue DamageUNDAMAGED MODULUS
NDT REDUCED TIME
NDT MODULUSDAMAGE
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Existing Asphalt ConcreteLevel 2 and 3
Damaged Modulus Mastercurves
100
1000
10000
100000
1000000
10000000
1E-08 0.000001 0.0001 0.01 1 100 10000 1000000 1E+08
Reduced Time
Mod
ulus
(psi
)
0.000.200.501.001.502.003.005.0010.0020.00
Fatigue DamageUNDAMAGED MODULUS
FROM CRACKINGOR
CONDITION RATING
DAMAGED MODULUS
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Unbound Materials
RM σε
∆=∆
εc
σc
∆ε
∆σ MR
εa
σa
• Resilient Modulus – Structural Response– Rutting
• Poisson’s Ratio Estimated From Modulus
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Stress Dependence of MR
2 3k k
octR 1 a
a a
M k p 1p p
τθ= +
(NCHRP 1-28A)
Bulk (Confining) Stress• Stiffening term (k2 > 0)• Dominates for coarse
granular soils (base, subbase)
Shear (Deviatoric) Stress• Softening Term (k3 < 0)• Dominates for fine-grained
soils (subgrade)
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Moisture Effects on MR
( )1 exp ln
10m opt
R env Ropt
b aab k S Sa
env
M F M
F
− +
+ − + −
=
=S = degree of saturationS = saturation at OMCk = regression coefficientma,b = constants (function of soil type)
S = degree of saturationS = saturation at OMCkm= regression coefficienta,b = constants (function of soil type)
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Moisture Effects on MR
Coarse Grained
Fine Grained
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Unbound Materials
Input Level
Design Type Characterization Method
New Laboratory Resilient Modulus (MR) testRehab NDT backcalculated MR
New MR = f (other properties)Rehab MR = f (other properties)New MR = f (soil classification)Rehab MR = f (soil classification)
1
2
3
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Unbound MR: Level 1 New
RM σε
∆=∆
εc
σc
∆ε
∆σ MR
εa
σa
LTPP P-46/AASHTO T307
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Unbound MR: Level 1 Rehab
• Backcalculate From FWD
• EDESIGN=CF(EFWD)– CF= user defined
Typical values: CF = 0.40 for subgrade, 0.67 for base/subbase
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• Correlations to Other Tests– DCP CBR=(292/PR)1.12
– CBR MR=2555(CBR)0.64 psi
– R-value MR = 1155+555(R) psi
• Correlations Using Gradation and PI• Conversion of Layer Coefficient
– MR=30000(ai/0.14)3 psi
Unbound MR: Level 2
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1 2 3 4 5 10 15 20 40 60 80 100
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P oor M edium G ood Exce llen tS u b g rad e S o il C ateg ory
A A S H TO S o ilC lassification
M r (ks i)
C B R (% )
R - Valu eA -1-b
A -2-7A -3
A-4A -5
A -6
A -7-6
A-1-a
A -7-5
A -2-5A -2-4
A -2-6
Unbound MR: Level 3
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Other Materials
• Portland Cement Concrete• Cementitiously Stabilized Materials
– CTB– Soil Cement
• PCC Slabs– Intact– Rubbilized
Resonant Pavement Breaker
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Summary
• Modulus is Key Material Input Parameter
• Hierarchical Input Levels– Level 1: Measured– Level 2: Correlations– Level 3: Defaults
• Agency Choice
50 6040302015108654321.5
1 2 3 4 5 10 15 20 40 60 80 100
1008060403020151054321
P oor M edium G ood Exce llen tSu b g rade So il C ateg o ry
A A S H T O S oilC lassification
M r (ks i)
C B R (% )
R - Valu eA -1-b
A-2-7A-3
A -4A-5
A -6
A -7-6
A -1 -a
A -7-5
A-2-5A -2-4
A -2-6
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Summary
• New and Rehabilitation• Load Influences Addressed
– Rate for AC– Stress State for Unbound
• Environmental Influences Addressed– Temperature in AC– Moisture in Unbound
Resonant Pavement Breaker
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Questions?