Development and Implementation of the Reflective Cracking Model in the Mechanistic-Empirical Pavement Design Guide Organizer: TRB Standing Committee on Pavement Rehabilitation August 17, 2016
Today’s Presenters • Moderator
Mostafa Elseifi, Louisiana State University
• Development of the Reflection Cracking Model in the Mechanistic-Empirical Pavement Design Guide Robert L. Lytton, Texas A&M University
• Reflection Cracking Integration into Pavement ME Design Harold L. Von Quintus, ARA/TRANS
• Questions & Answers
NCHRP is...
A state-driven national program
• The state DOTs, through AASHTO’s Standing Committee on Research... – Are core sponsors of NCHRP
– Suggest research topics and select final projects
– Help select investigators and guide their work through oversight panels
NCHRP delivers...
Practical, ready-to-use results • Applied research aimed at state
DOT practitioners • Often become AASHTO
standards, specifications, guides, manuals
• Can be directly applied across the spectrum of highway concerns: planning, design, construction, operation, maintenance, safety
A range of approaches and products • Traditional NCHRP reports • Syntheses of highway practice • IDEA Program • Domestic Scan Program • Quick-Response Research for
AASHTO • Other products to foster
implementation: – Research Results Digests – Legal Research Digests – Web-Only Documents and CD-ROMs
NCHRP Webinar Series • Part of TRB’s larger webinar
program • Opportunity to interact with
investigators and apply research findings.
Today’s First Presenter
• Development of the Reflection Cracking Model in the Mechanistic-Empirical Pavement Design Guide Robert L. Lytton, Texas A&M University
Development of the Reflection Cracking Model in the Mechanistic-Empirical Pavement Design Guide
Robert L. Lytton
Webinar August 17, 2016
National Cooperative Highway Research Program
1
2
Traffic Material Properties
Climate EICM
Pavement Structure
Pavement Response (σ, ε) Model: Multi-layer
elastic system
Pavement Distress Models
Pavement Performance Predictions
INPUT
OUTPUT
MODELS
Interlayer
Existing Pavement Conditions
Pavement Response Model Stress Intensity Factor (SIF)
Artificial Neural Network (ANN)
Pavement Distress Model Reflection Cracking
(Thermal, Shearing, Bending)
Pavement Performance Prediction: Reflection Cracking
Extent and Severity
MEPDG Model Reflection Cracking Model
Flow Chart in Overall
3
Selected Test Sections • 10 models
Field Data Collection • Distress • Traffic • Pavement • Weather
Field Data Analysis • Distress • Traffic • Axle load distribution
Temperature Model • Weather data • Modeling temperature with
depth • New temperature model
Crack Propagation Model • Temperature
• Traffic shear
• Traffic bending
• Artificial neural network models Modulus Stress intensity factors
• Viscoelastic thermal stress • Crack growth
Calibration Process • Asphalt modulus
Falling weight deflectometer
Artificial neural network • Calculated number of days
Thermal (2) Shear (2) Bending (1)
• Calibration to field distress Five calibration
coefficients Three levels of damage
Mechanisms of Reflection Cracking
4
Thermal crack growth
Traffic crack growth
Thermal expansion and contraction
Traffic movement
Bituminous surfacing
Lean concrete roadbase
Sub-base
Bending Stress Shearing Stress Thermal Stress
Overlay
Position I NfB1 NfS1
NfS2
NfT1
NfT1
C
Bending Stress
Shearing Stress
Stre
sses
at T
ip o
f Cra
ck
Overlay
Old Concrete Layer
Base Course
Tip of Crack
5
6
WF
DF
WNF
DNF
Field Data Collection – LTPP Test Sections
Field Data Collection - Test Sections
7
Category (Overlay/ Exist. Layer) Total Test Sections
No. of Test Sections
WF DF WNF DNF
AC/AC 108 59 16 33
AC/Mill/AC 125 62 47 16
AC/CRC 21 21
AC/JRC(JPC) 69 69
AC/SC(FC) 38 26 12
AC/Reinforcing/AC 11 11
AC/Reinforcing/JPC 31 24 7
Total 403 261 27 99 16
• Section 340503 (WF zone in New Jersey) – AC/AC overlay rehabilitation: July 27th, 1992 – Transverse crack length before overlay: 88.2m
Data Collected from LTPP Sections
8
0
10
20
30
40
50
60
7/27/9
2
12/9/
93
4/23/9
59/4
/96
1/17/9
86/1
/99
10/13
/00
2/25/0
2
7/10/0
3
11/21
/04
Observation Date
Ref
lect
ive
Cra
ck L
engt
h (m
)
0.00.10.20.30.40.50.60.70.80.91.0
0 1000 2000 3000 4000 5000
No. of Days after Overlay
Cra
ck L
engt
h (ra
tio)
Observed crack length Ratio of reflection crack length to max. length
• The amount and severity of reflection cracking follows a sigmoidal curve (S-shape)
Development of Reflection Cracking
9
0
1020
3040
5060
7080
90
0 200 400 600 800 1000 1200 1400 1600
Traffic or Time
AR
EA (%
)
High Severity
High+Medium Severity
High+Medium+Low Severity
• Factors in reflection cracking model
– Scale factor ρ : how wide the rising portion of curve is – Shape factor β : how steep the rising portion of curve is
Reflection Cracking Model
10
100 TotalDRFAS e
βρ
− = ⋅
β < 1.0
β > 1.0
Crack Length
Traffic or Time
Crack Length
Traffic or Time
t =ρ1 t =ρ2 t =ρ3
e-1 = 36.8%
β = 1.0
• LTPP section 340503 (WF zone in New Jersey) – AC/AC overlay
Calibrated Models for LTPP Sections
11
0.00.10.20.30.40.50.60.70.80.91.0
0 1000 2000 3000 4000 5000
No. of Days after Overlays
Ref
lect
ive
Cra
ck L
engt
h (r
atio
)
Severity Parameter
β ρ
H+M+L 2.365 3617.12
H+M 4.107 4761.25
H N/A N/A
Calibrated Parameters Values measured predicted H+M+L H+M H
Mechanisms of Reflection Cracking
12
Thermal crack growth
Traffic crack growth
Thermal expansion and contraction
Traffic movement
Bituminous surfacing
Lean concrete roadbase
Sub-base
Bending Stress Shearing Stress Thermal Stress
Overlay
Position I NfB1 NfS1
NfS2
NfT1
NfT1
C
Rectangular Tire Patch Length
Tire LoadTire Length Tire Pressure Tire Width
=×
Tire Length
Width
Uniform Pressure
13
Eight Categories on Axle Type and Number of Tires
14
Vehicle Class Single Axle Tandem Axle Tridem Axle Quad. Axle
4
No. 1 No. 3 No. 5 No. 7
5 6
No. 4 No. 6 No. 8
7 8
No. 2
9 10 11 12 13 14
Dual Tires
Single Tires
Example: Category 1 of LTPP Section 180901 in 2004
15
0.00
0.20
0.40
0.60
0.80
1.00
0 3 6 9 12 15 18 21
Tire Length (in.)
Cu
mu
lati
ve A
xle
Lo
ad D
istr
ibu
tio
n Measured
Model
L 2
P 2
L 1
P 1
• Model developed by Dr. Charles Glover’s research group, Department of Chemical Engineering, Texas A&M.
Pavement Temperature Model
16
(Model source: Xin Jin, Rongbin Han, and Dr. Charles Glover, Department of Chemical Engineering, Texas A&M University)
α : Albedo Ta: Air temperature qs: Solar radiation ε : emissivity coefficient εa : absorption coefficient
к: Thermal conductivity
Solar radiation Atmospheric downwelling
longwave radiaiton
Outgoing longwave radiation
Heat convection by wind
Pavement Heat conduction
Albedo Distribution in Winter
17
0.15-0.2 0.3-0.35
0 2 4 6 8 10 12 14 16 18 20 22 24 26
-8
-6
-4
-2
0
2
4
6
8Te
mpe
ratu
re F
lutua
tion
Patte
rn A
roun
d Da
ily A
vera
ge T
empe
ratu
re (D
egre
e C)
Hours
Texas (48-1000) Texas (48-0800) Texas (48-A800) South Dakota (46-0800) Utah (49-0800) Nevada (32-0100)
18
Pavement Structural Cases
19
Modeling of Stress Intensity Factor (SIF) by Artificial Neural Network (ANN) (1/2)
20
AC_AC AC_PCC
Modeling of Stress Intensity Factor (SIF) by Artificial Neural Network (ANN) (2/2)
21
Pure_Bending_AC_AC_Single_Tire_Together Pure_Bending_AC_AC_Single_Tire_Together (Only Positive)
• Witczak 2006 Model
Modeling of Relaxation Modulus by Artificial Neural Network (ANN) (2006 Model)
22
Input Output
R2 Gradation Volumetric Binder Data Witczak ANN
3/4 (%)
3/8 (%)
#4 (%)
#200 (%)
Va
(%) Vbeff
(%) Log|G*| 106 psi
δc
deg E* psi 0.77 0.96
0
10
20
30
40
50
60
0 10 20 30 40 50 60
Pre
dict
ed IE
*I (G
Pa)
Observed IE*I (GPa)
Witczak 2006 ANN 2006
Crack Growth Model - Paris’ Law
23
( )
10
32 1 4
0
log log log
( )
nk
mix
tmix
t nk
dc A K adN
gn gm
gA g D gm
a w t dt
σ
∆
= ⋅ ∆ ⋅
= +
= + +
= ∫D1 = creep compliance coefficient σt = tensile strength mmix = slope of complex moduli versus loading times g0 ~ g6 = coefficients varying with climate zones ak = the viscoelastic stress pulse effect
Loading Time
E(t,T)
mmix
11.95
11.56
( , ) 10000.005 / , 77 , 6.8956.895 21.3
( , ) 10000.5 / , 77 , 6.8956.895 45.5
t
t
E t Tr in mm T F Temperature
E t Tr in mm T F Traffic
σ
σ
× = = = − > ×
× = = = − > ×
24
Crack Growth Model - Paris’ Law
Coefficient Climatic Zone
Wet-Freeze Wet-No Freeze Dry-Freeze Dry-No Freeze g0 -2.09 -1.429 -2.121 -2.024 g1 1.952 1.971 1.677 1.952 g2 -6.108 -6.174 -5.937 -6.107 g3 0.154 0.19 0.192 1.53 g4 -2.111 -2.079 -2.048 -2.113 g5 0.037 0.128 0.071 0.057 g6 0.261 1.075 0.762 0.492
25
Load Wave Shape for Tandem Axle
Crack or Joint
L j L j
4.0 ft
Overlay
Old Surface
5.0 ft L j
W ( t ) Load Wave Shape
[ W ( t )] n
2.0 ft 2.0 ft
5.0 ft L j
0.72 0.82
0.92 0.92
0.82 0.72
0.0 0.0
0.0 0.0
(0.72) n
(0.92) n
(0.82) n (0.82) n
(0.92) n
(0.72) n
(0.095) n
0.095
∆ t
(1 4 + L j ) ft.
Overlay
C
Thermal Stress Shear Stress
Bending Stress
Position I
Position II
NfB1 NfT1 NfS1
NfT2 NfS2
• NfB1 = Number of days for crack growth due to bending to reach Position I.
• NfT1 = Number of days for thermal crack growth to reach Position I.
• NfS1 = Number of days for crack growth due to shearing stress to reach Position I.
• NfT2 = Number of days for thermal crack growth to go from Position I to Position II.
• NfS2 = Number of days for crack growth due to shearing stress to go from Position I to Position II.
26
Calculated Number of Days
100%
0
Number of Days Damage
Perc
ent o
f Ref
lect
ed
36.8%
High severity
Medium+ High
High + Medium+ Low
ρLMH ρMH ρH
27
Calibration Quantities
Calibration Model Set
1 1 21 0 1 2 2 3 4
1 1 2
0 1 2 3 4
1 1 21 5 6 7 2 8 9
1 1 2
: , , , , ,
fB fB fTLMH fB fT
fT fS fS
LMH
fB fB fTMH fB fT
fT fS fS
N N NN N
N N N
Calibration Coefficients
N N NN N
N N N
Calibration Coeffi
ρ α α α α α
α α α α α β
ρ α α α α α
= + + + +
= + + + +
5 6 7 8 9
1 1 21 10 11 12 2 13 14
1 1 2
10 11 12 13 14
: , , , , ,
: , , , , ,
MH
fB fB fTH fB fT
fT fS fS
H
cients
N N NN N
N N N
Calibration Coefficients
α α α α α β
ρ α α α α α
α α α α α β
= + + + +
28
HOW DOES THE TIME-SCALE PARAMETER, ρ , VARY WITH
OVERLAY THICKNESS?
SENSITIVITY ANALYSIS
29
Sensitivity analysis of ρLMH for AC over AC pavement structure in a Dry-No Freeze
climate zone
30
10
100
1000
10000
100000
0 2 4 6 8
Scal
e co
effic
ient
(ρLM
H),
log
Thickness, inch
3002
5003
5004
3003
3004
3005
3006
3001
5006
5007
5008
3007
3008
Sensitivity analysis of ρH for AC over AC pavement structure in a Dry-No Freeze
climate zone
31
10
100
1000
10000
100000
1000000
0 2 4 6 8
Scal
e co
effic
ient
(ρH),
log
Thickness, inch
3002
5003
5004
3003
3004
3005
3006
3001
5006
5007
5008
3007
3008
Sensitivity analysis of ρMH for AC over JPC pavement structure in a Wet-Freeze
climate zone
32
10
100
1000
10000
100000
0 2 4 6 8 10 12
Scal
e co
effic
ient
(ρM
H),
log
Thickness, inch
12002 12003
13001 14005
14007 15002
22001 22004
30001 30002
30003 38003
38001 38005
13002 20005
22006 27001
32001 12001
12007 13008
14009 20008
20009 32002
38006
Sensitivity analysis of ρLMH for AC over Reinforcing over PCC pavement structure
in a Wet-Freeze climate zone
33
10
100
1000
10000
100000
0 2 4 6 8
Scal
e co
effic
ient
(ρLM
H),
log
Thickness, inch
25005 25007
25008 25009
25010 25011
25012 25013
25014 25015
25016 25017
25006 25018
25019 25020
25021 25022
25023 25024
25025 25026
25027 25028
Reflection Cracking Integration into Pavement ME Design
Harold L. Von Quintus
Webinar August 17, 2016
American Association of State and Highway
Transportation Officials
34
Outline for Session 2: 1. Overview of Enhancement to MEPDG 2. Inputs – Specific to Reflection Cracking 3. Calibration of Reflection Cracking Transfer
Function 4. Application/Demonstration of Reflection
Cracking Models for Rehabilitation Design
Enhancement to AASHTOWare Pavement ME® Design in FY2015:
Version 2.2 & 2.3
35
1. Judith Corley-Lay, P.E.; NCDOT, Chairperson 2. Vicki Schofield, AASHTO Project Manager 3. John Donahue, P.E.; Missouri DOT 4. William Barstis, P.E.; Mississippi DOT 5. Jay Goldbaum, P.E.; Colorado DOT 6. Marta Juhasz, P.E.; Alberta Transportation 7. Mehdi Parvini, P.E.; California DOT 8. Felix Doucet; TAC Liaison 9. Tom Yu, P.E.; FHWA Liaison 10. Shane Marshall, P.E.; Utah DOT, SCOJD Liaison 11. Jack Dartman, Montana DOT; T&AA Liaison
AASHTO Pavement ME Design Task Force Members:
36
Reflection Cracking Integration into Pavement ME Design
Based on results and methodology developed from NCHRP Project 1-41
A special thank you to: Bob Lytton and Sheng Hu (Texas Transportation
Institute): explanation on the models/equations. Halil Ceylan (Iowa State University): completed neural
networks.
37
Enhancement to MEPDG
Earlier Version; pre 2.2 Regression equation Fatigue cracks
Version 2.2 & Higher Fracture mechanics Fatigue cracks Transverse cracks
( ) ( )dbtcaeRC ++
=1
100( )( )
+
=iDILogci ec
CRCR5
4
100
38
Enhancement to MEPDG Earlier Version; pre 2.2 1. AC over AC 2. AC over PCC
Version 2.2 & Higher 1. AC over AC 2. AC over AC with seal
coat and interlayer 3. AC over intact JPCP 4. AC over fractured JPCP 5. AC over CRCP 6. Semi-Rigid Pavement 7. AC over Semi-Rigid
( ) ( )dbtcaeRC ++
=1
100( )( )
+
=iDILogci ec
CRCR5
4
100
39
Enhancement to MEPDG
Expanded Pavement Design Types: 1. Overlay with seal coat
and interlayer 2. Semi-rigid pavement 3. Overlay of semi-rigid
pavement 4. Overlay of PCC; intact
and fractured
40
Outline for Session 2: 1. Overview of Enhancement to MEPDG 2. Inputs – Specific to Reflection Cracking 3. Calibration of Reflection Cracking Transfer
Function 4. Application/Demonstration of Reflection
Cracking Models for Rehabilitation Design
41
Inputs to Software Performance criteria and reliability Condition of existing pavement Load transfer efficiency of cracks and/or joints Mixture properties
42
Performance Criteria and Reliability
AC of AC AC seal coat and interlayer of AC
AC of AC Pavements
43
Performance Criteria and Reliability
AC of PCC Pavements
AC of intact JPCP AC of fractured JPCP
AC of CRCP
44
Condition of Existing Pavement AC over AC AC over Semi-Rigid
45
Condition of Existing Pavement AC over Fractured JPCP
46
Condition of Existing Pavement Semi-Rigid Pavement
47
Load Transfer Efficiency Flexible and PCC pavements Measured in accordance with LTPP procedure Tied to crack severity for calibration
Severity LTE, percent Low 85
Medium 50 High 30
48
Overlay Mixture Properties No “new” or additional mixture properties needed
49
Outline for Session 2: 1. Overview of Enhancement to MEPDG 2. Inputs – Specific to Reflection Cracking 3. Calibration of Reflection Cracking Transfer
Function 4. Application/Demonstration of Reflection
Cracking Models for Rehabilitation Design
50
Sampling Matrix Ex
istin
g Pa
vem
ent
Con
ditio
n
Ove
rlay
Thic
knes
s Interlayer/Climate AC None Seal Coat
DF DNF WF WNF DF DNF WF WNF DF DNF WF WNF
Good Thick — — — — 8 — 6 2 3 — — — Thin — — 1 1 3 3 30 37 3 — — 3
Mod. Thick — — — — 3 — 5 — 1 — — 1 Thin — — — 1 3 3 22 7 2 — 2 1
Poor Thick — — — — 1 1 3 — 1 — — — Thin — — 1 4 8 5 30 13 4 — — 2
AC over AC Pavements
Data Sources: LTPP and other agency test sections. Total Number of Test Sections: 58
51
Sampling Matrix AC over PCC Pavements
Pavement Type
Existing Condition
Overlay Thickness
Climate
DF DNF WF WNF
Fractured Not Applicable Thick 4 18 31 8 Thin — — 3 1
Intact Good/Moderate
Thick 5 5 25 13 Thin 2 — 20 7
Poor Thick 2 2 22 — Thin 2 1 10 —
Data Sources: LTPP, New York City composite test sections, other agency test sections; 60 test sections.
52
Sampling Matrix Semi-Rigid Pavements
Pavement Type
Existing Condition
Overlay Thickness
Climate
DF DNF WF WNF
New AC over CTB Not Applicable
Thick 5 35 40 17
Thin 5 2 1 8
Data Sources: LTPP other agency test sections; Total number of sections: 55
53
Calibration Coefficients
Calibration Coefficients
Pavement Type AC over
AC AC over
Intact JPCP
AC over CRCP or Fractured
JPCP
Semi-Rigid
AC over Semi-Rigid
K1 0.012 0.012 0.012 0.45 0.012 K2 0.005 0.005 0.0002 0.05 0.005 K3 1.00 1.00 0.1 1.0 1.0 C1 3.22 0.1 1.0375 0.1 3.22 C2 25.7 0.52 1.8929 0.9809 25.7 C3 0.1 3.1 0.1 0.19 0.1 C4 133.4 79.3 262.1 165.3 133.4 C5 -72.4 -27.1 -9.6645 -5.1048 -72.4
Transverse Cracks
Critical coefficients, local calibration: C1, C2 and C5. 54
Calibration Coefficients
Calibration Coefficients
Pavement Type AC over
AC AC over
Intact JPCP
AC over CRCP or Fractured
JPCP
Semi-Rigid
AC over Semi-Rigid
K1 0.012 NA NA 0.45 0.012 K2 0.005 NA NA 0.05 0.005 K3 1.00 NA NA 1.00 1.00 C1 0.38 NA NA 1.64 0.38 C2 1.66 NA NA 1.1 1.66 C3 2.72 NA NA 0.19 2.72 C4 105.4 NA NA 62.1 105.4 C5 -7.02 NA NA -404.6 -7.02
Fatigue Cracks
Critical coefficients, local calibration: C1, C2 and C5. 55
Calibration Coefficients
AC over Flexible Pavements:
Fatigue Cracks
Transverse Cracks
56
Outline for Session 2: 1. Overview of Enhancement to MEPDG 2. Inputs – Specific to Reflection Cracking 3. Calibration of Reflection Cracking Transfer
Function 4. Application/Demonstration of Reflection
Cracking Models for Rehabilitation Design
57
Application of Models Sensitivity of load transfer efficiency or crack severity:
Load transfer efficiency is important.
58
Application of Models Eastern Colorado Existing AC Thickness: 6
in.
Distress Severity: Medium 90% Reliability
Effect of AC overlay thickness.
59
Application of Models Fractured JPCP Southern Arizona
Slab thickness – 10 inches AC overlay – 5 inches
Effect of reliability for transverse cracking.
60
Application of Models Fractured JPCP 90% Reliability
Slab thickness – 9 inches AC overlay – 5 inches
Effect of LTE for fractured JPCP.
61
Application of Models Fatigue cracking predictions for AC over AC.
62
Application of Models Transverse cracking predictions for AC over AC.
63
Application of Models Transverse cracking predictions for AC over fractured PCC.
Block cracking recorded in LTPP.
64
Reflection Cracking addendum is available through the ME-Design Resource Website for downloading the software: http:www.me-design.com Addendum #FY2015.4; dated August 2015.
65
QUESTION AND ANSWER SESSION
Comments & suggestions for future webinars are welcomed.
66
Top Related