AAPA 2010 Study Tour – Perpetual Pavement Concepts
Perpetual Pavement Concepts
Ian Rickards | Jason Jones |Russell ClaytonGreg Stephenson | Young Choi
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Perpetual Pavements
• Understanding the concepts• Theory behind fatigue endurance limits• Field validation of the concept• Examples of designs • Material characterisation• Impacts on ME pavement design approach• How to introduce into design and construction
www.aapa.asn.au
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Sessions
• University of CaliforniaoCarl Monismith
• NAPA – Asphalt Pavement AllianceoDavid Newcomb
• University of IllinoisoMarshall Thompson
• National Centre for Asphalt TechnologyoDavid Timm
www.aapa.asn.au
AAPA 2010 Study Tour – Perpetual Pavement Concepts
What is a Perpetual Pavement?• No deep structural distress
AAPA 2010 Study Tour – Perpetual Pavement Concepts
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Goal of Perpetual Pavement Design• Design so there are no deep structural distresses
o Bottom up fatigue crackingo Structural rutting
• All distresses can be quickly remedied from surface• Result in a structure with ‘Perpetual’ or ‘Long Life’
Perpetual Pavements
Performance Goals - Avoid These
RepeatedBending
Leads toFatigue Cracking
RepeatedDeformation
Leads toRutting
HMA
Base
Subgrade
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Max Tensile Strain
PavementFoundation
Rut Resistant Intermediate Course75 – 100 mm (3 – 4”)
Durable Base100 – 250 mm (4 – 10”)
38 – 75 mm (1.5 - 3”) SMA, OGFC or Superpave}Zone ofHigh
Compression
Perpetual Pavement Concept
AAPA 2010 Study Tour – Perpetual Pavement Concepts
{Rehabilitation
50 - 100 mm
Stru
ctur
e Re
mai
ns In
tact
Possible Distresses› Top-Down Fatigue› Thermal Cracking› Raveling
Solutions› Mill & Fill› Thin Overlay
High Quality SMA, OGFC or Superpave
20+ YearsLater
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Top-Down Cracking
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Perpetual Pavements• Resist Structural DistressesoFatigue CrackingoRutting
• Withstand Climate and TrafficoDesign for Subgrade ModulusoUse Strong FoundationoMix DesignoMaterials Selection
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Materials• FoundationoNot Much ChangeoSoilsoGranular MaterialsoStabilization
• Asphalt Materials and Mix DesignoBase Layero Intermediate LayeroWearing Course
AAPA 2010 Study Tour – Perpetual Pavement Concepts
› Rut Resistant Upper Layers• Aggregate Interlock
» Crushed Particles» Stone-on-Stone Contact
• Binder» High Temperature PG» Polymers» Fibers
• Air Voids» Avg. 4% to 6% In-Place
• Surface» Renewable» Tailored for Specific Use
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Construction• Foundation requirements for construction• Interlayer friction• Density – especially in asphalt base layer• Overly stiff mixtures• Segregation• Joint density• Asphalt layer bonding• QC/QA
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Interlayer Bonding
• Ensure complete tack coverage• Use trackless or polymer modified or hot tack• Keep traffic to a minimum
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Perpetual Pavement Advantage• Efficient Design – No Overdesign• Avoid Reconstruction• Reduce Rehabilitation• Reduce Life Cycle Cost• Reduce Energy Consumption• Reduce Materials Use
Perpetual PavementsWhy are Perpetual Pavements Important?
• Lower Life Cycle Cost– Better Use of Resources– Low Incremental Costs for Surface
Renewal• Lower User Delay Cost
– Shorter Work Zone Periods– Off-Peak Period Construction
AAPA 2010 Study Tour – Perpetual Pavement Concepts
M-E Perpetual Pavement Design
No Damage Accumulation
Log N
Log e
ThresholdStrainE1
E2
E3
D1
D2
D3
P
A
et
ev
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Fatigue Endurance Limit
• Definition:o The stress or strain level below which no fatigue
damage originating from the bottom of the pavement occurs.
AAPA 2010 Study Tour – Perpetual Pavement Concepts
SHRP Fatigue Test Equipment
AAPA 2010 Study Tour – Perpetual Pavement Concepts
AustralianBeam Fatigue Apparatus(based on SHRP equip.)
AAPA 2010 Study Tour – Perpetual Pavement Concepts
FATIGUE TESTING
• Tensile Strain in Flexural Beam Testo Other Configurations
o 10 Hz Haversine Load, 20o C, Controlled Strain
AAPA 2010 Study Tour – Perpetual Pavement Concepts
HMA FATIGUE
N (LOG)
e AC (L
OG
)N = K1 (1 / eAC)K2
FATIGUE DAMAGE
ENDURANCE LIMIT
NO FATIGUE DAMAGE
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Fatigue Endurance Limit• Investigated by Monismith 1972
o Suggested a limit of 70 e• Recent Studies
oU. of Illinois, Carpenter, Ghuzlan, and Shen; use of damage accumulation ratio.
(DDE/DE)oNCHRP Project 9-38, NCAT (Auburn U.)oNCHRP Project 9-44, APT (Ray
Bonaquist)oNCHRP Project 9-44A, U. of Arizona (M.
Witczak)
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Fatigue Endurance Limit
• NCHRP Projects:o 09-38: Endurance Limit of Hot Mix Asphalt
Mixtures to Prevent Fatigue Cracking in Flexible Pavements – Completed
o 09-44: Developing a Plan for Validating an Endurance Limit for HMA Pavements – Completed
o 09-44A: Validating an Endurance Limit for HMA Pavements: Laboratory Experiment and Algorithm Development – Active
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Normal Fatigue Testing Results VersusEndurance Limit Testing
0
200
400
600
800
1000
1200
1000 100000 10000000 1.1E+08
Number of Loads to Failure
Stra
in, (
10E
-06)
Endurance Limit
Normal Range forFatigue Testing
0
200
400
600
800
1000
1200
1000 100000 10000000 1.1E+08
Number of Loads to Failure
Stra
in, (
10E
-06)
Endurance Limit
0
200
400
600
800
1000
1200
1000 100000 10000000 1.1E+08
Number of Loads to Failure
Stra
in, (
10E
-06)
Endurance Limit
Normal Range forFatigue Testing
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Fatigue Endurance Limit
• Project 09-38oNCHRP Report 646
• Fatigue Endurance Limit Test Procedure:oControlled strain
• 50% reduction in modulusoFatigue beam testing at different strain levelsoFatigue endurance limit
• Strain to achieve 5 x 107 loading cyclesoTest Duration
• 50 days to test a beam to 5 x 107 loading cycles
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Fatigue Endurance LimitBinder 95% Lower
Confidence LimitPG 58 – 22 82 e
PG 64 – 22 75 e
PG 67 – 22 151 e
PG 67 – 22 Optimum +
158 e
PG 76 – 22 146 e
PG 76 – 22 Optimum +
200 e
AAPA 2010 Study Tour – Perpetual Pavement Concepts
AAPA 2010 Study Tour – Perpetual Pavement Concepts
N8 and N9
2.3 2.0
2.9 3.5
2.8 3.1
1.92.6
3.26.4
8.4
0.0
5.0
10.0
15.0
20.0
25.0
N8 N9Section
Dep
th F
rom
Pav
emen
t Sur
face
, in.
Lift 1
Lift 2
Lift 3
Lift 4
Lift 1
Lift 2
Lift 3
Lift 4
Lift 5
Aggregate Base(Track Fill)
Subgrade(A-7-6 Soil)
Rich Bottom LayerPG 64-22
Dense Graded HMAPG 64-22
Dense Graded HMAPG 76-28
SMAPG 76-28
Moisture Content = 10.8%Unit Weight = 133.4 pcf
Moisture Content = 12.9%Unit Weight = 133.8 pcf
Moisture Content = 18.0%Unit Weight = 126.2 pcf
Moisture Content = 17.2%Unit Weight = 126.9 pcf
31
Field Strain Measurements (1/2)Direction of TravelDirection of TravelDirection of Travel
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Strain Measurements
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Strain and Temperature
0
200
400
600
800
1000
120001
-Nov
-06
31-D
ec-0
6
01-M
ar-0
7
30-A
pr-0
7
29-J
un-0
7
28-A
ug-0
7
27-O
ct-0
7
26-D
ec-0
7
24-F
eb-0
8
24-A
pr-0
8
Date
Long
itudi
nal M
icro
stra
in-S
ingl
e A
xle
0
20
40
60
80
100
120
Mid
-Dep
th P
avem
ent T
empe
ratu
re,F
N8-Strain
N9-Strain
N8-Temperature
N9-Temperature
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Strain vs. Temperature
N8 Strain = 21.249e0.033*Temp
R2 = 0.9584
N9 Strain = 11.136e0.0293*Temp
R2 = 0.9309
0
200
400
600
800
1000
1200
0 20 40 60 80 100 120 140
Mid-Depth Pavement Temperature, F
Long
itudi
nal M
icro
stra
in-S
ingl
e A
xle
Section Axle Type C1 C2 R2
Single 21.249 0.033 0.96Tandem 15.326 0.035 0.96
Steer 11.341 0.036 0.87Single 11.136 0.029 0.93
Tandem 8.600 0.030 0.92Steer 5.901 0.030 0.93
N8
N9
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Strain History – Section N8
0
200
400
600
800
1000
1200
140011
/1/2
006
12/1
/200
6
12/3
1/20
06
1/30
/200
7
3/1/
2007
3/31
/200
7
4/30
/200
7
5/30
/200
7
6/29
/200
7
7/29
/200
7
8/28
/200
7
9/27
/200
7
10/2
7/20
07
Time
Long
itudi
nal M
icro
stra
in-S
ingl
e A
xles
0
20
40
60
80
100
120
140
Tem
pera
ture
, F
Temperature
Strain
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Strain Distributions
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 100 200 300 400 500 600 700 800 900 1000 1100 1200Longitudinal Strain
Per
cent
ile
N9 N8
AAPA 2010 Study Tour – Perpetual Pavement Concepts
NCAT Test Track Results
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 200 400 600 800 1000 1200Microstrain
Perc
entil
e
N1 2003N2 2003N3 2003N4 2003N5 2003N6 2003N7 2003N1 2006N2 2006N3 2006N4 2006N8 2006N9 2006N10 2006S11 2006S13 2000
FatigueNo Fatigue
Tested to 2 x 107 ESALs
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Further Documentation
http://www.ncat.us/reports/rep09-09.pdf
The Phase One I-710 Freeway Rehabilitation Project: Initial Design to Performance After
Six Years of Traffic
Meeting with AAPA Study Tour GroupUCPRC, CA 8/10/2010
Richmond Field Station, UC Berkeley
I-710 Traffic
150,000 vehicles per day15% heavy vehicles
I-710 Project - Partnered Effort
(most recent participants)• Caltrans
T. Bressette, W. Farnbach, C. Suszko
• Industry J. St. Martin,
• University of California PRC C. Monismith
I-710March 2003
Rehabilitation ofInterstate - 710
• Full-Depth Asphalt Concrete replacement under overpasses
• Overlay of PCC (cracked-seated)
Design & AnalysisTrial cross
section
Performance Tests
Trial mix
design
Conditioning(Aging &
Water)
Analysis Performance
Prediction
Final mix design & structural
section
UnacceptableAcceptable
Long-Life Asphalt Pavement
• QC/QA specifications • Polymer modified binders
• Improved aggregate requirements
• Modified mix design method
Trial Mix Design• Range of binder contents 4.2 - 5.7% (by wt of aggregate)
• Conventional dense-graded mix, Caltrans specs.
• All crushed materials
Shear Test
HVS Rutting Study
Mix Performance Evaluation
0
5
10
15
20
25
30
- 50,000 100,000 150,000 200,000HVS Load Applications
Rut
Dep
th, m
m
38-mm ARHM-GG
62-mm ARHM-GG
75-mm DGAC AR-4000
76-mm PBA-6A
½ inch rut depth
< 20,000 reps ~ 170,000 reps
Trial Pavement Sections
AR-8000
PBA-6A*
AR-8000(rich bottom)
subgrade
Design Considerations
• Fatigue in asphalt concrete• Deformation in unbound layers
• Subsequently, design checked by CalME
Fatigue
Fatigue Test Results
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
1.E+08
1.00E-04 1.00E-03Mean Strain
Nf
AR-8000, 4.7% AC, 6% AVAR-8000, 5.2% AC, 3% AVPBA-6A, 4.7% AC, 6% AVPBA-6A, 5.2% AC, 3% AV
Final Design
AR-8000 (4.7%)PBA-6A (4.7%)
AR-8000 (5.2%)(rich bottom)
subgrade
AR-OGFC 25 mm75
150
75
6% air voids6%
3%
Overlays
Jointed PCC
Cement treated Base
Subgrade
Asphalt ConcreteFabric
Leveling Course
150 – 250 mm
200 mm
150 mm
30 mm
Construction Specifications
• Performance requirements based on shear and fatigue testing
• More stringent compaction requirements
• Tack coat between layersAsphalt cement (AR- 4000)
Construction• Six stages• Stages 1 and 2 preliminary to
rehab. of trafficked sections• Stages 3-6 - rehab. of
trafficked sections in 8 - 55 hr. weekend closures (vs. 10 originally planned)
• Use of CA4PRS (construction management program)
Digout and Placement of Aggregate Base – Working
Platform
Monday, March 30, 2003 05:00am
Performance Evaluation• FWD Deflection testing (2003
through 2008)• Back calculation of layer moduli and
strains in HMA layers using MLEA• Condition surveys• Longitudinal and transverse profile
measurements• Noise measurements• Laboratory testing of cores (RSST-
CH) and slabs (Fatigue)
CENTER DEFLECTIONS LANE 3 I-710 NORTHBOUND (ADJUSTED TO 19C)
0
100
200
300
400
500
600
700
800
900
1000
0 50 100 150 200 250
LOCATION
DEF
LEC
TIO
N (M
ICR
ON
S)
2003
2004
2006
2008
Section 1(FD) Section 2(CSOL) Section 3(FD) Section 4(CSOL) Section 5(FD)
PCH 405
Deflections – NB Lane 3
X
03030508
Tensile Strain, Underside HMA Layer, in/in x 10-6
Section NB SB
1 18 49
3 17 18
5 16 8.5
Rut Depth MeasurementsSB Lane 3
0
3
6
9
12
15
0+00 5+00 10+00 15+00 20+00 25+00 30+00 35+00 40+00 45+00
Station (m)
Rutting (mm) Left WP Right WP
12.5 mm
I-710 Traffic
Perpetual Pavement Awards• Documents existing ‘long life’ flexible
pavements > 35 years old < 100 mm added ≥ 13 years between overlays
State Studies
Instrumented Sections Test Sections
69
Mixture Performance Testing
AAPA Study Tour 2010
70
OutlineMechanistic property for pavement designMixture resistance to ruttingMixture resistance to fatigue cracking
71
M-E Pavement Design
Climate
Traffic
Materials
Structure
DistressResponseTime
Damage
Damage Accumulation
Level 1: I know a lot about this input…Level 2: I know some about this input…Level 3: I know very little about this input…
72
Material Inputs for Asphalt MixtureThree levels of E* inputs
Level One – Lab-measured E*Level Two - Witczak 1-37A or Witczak 1-40DLevel Three - Witczak 1-37A or Witczak 1-40D
73
Dynamic Modulus |E*|
|E*| = σ0 /є0
74
Master Curve
10
100
1,000
10,000
-6 -4 -2 0 2 4 6Log Frequency, Hz
|E*|
, ksi
10
100
1,000
10,000
-6 -4 -2 0 2 4 6Log Frequency, Hz
|E*|
, ksi
10
100
1,000
10,000
-6 -4 -2 0 2 4 6Log Frequency, Hz
|E*|
, ksi
( ( Taffr logloglog
( rfe
E log1*log
70F
75
Predictive Models for E*Witczak NCHRP 1-37A model (1999)Witczak NCHRP 1-40D model (2005)Hirsch model (2003)
10,000 100,000 1,000,000 10,000,00010,000
100,000
1,000,000
10,000,000
Witczak 1-40D
Measured E* (psi)
Pred
icte
d E*
(psi
)
10,000 100,000 1,000,000 10,000,00010,000
100,000
1,000,000
10,000,000
Witczak 1-37A
Measured E* (psi)
Pred
icte
d E*
(psi
)
10,000 100,000 1,000,000 10,000,00010,000
100,000
1,000,000
10,000,000
Hirsch
Measured E* (psi)
Pred
icte
d E*
(psi
)
79
Flow Time (Ft)Test
D(t) = ε(t)/σd
80
Flow Number (FN) Test
81
Flow Number Test (cont.) - Primary: strain rate decreases- Secondary: constant strain rate- Tertiary: strain rate increases- Lower flow number, greater rutting in the field
82
Field Performance16 surface mixes (mix performance study)
8 mixes loaded to 5 million ESALs8 mixes loaded to 10 million ESALs
Weekly rutting measurementsTaken using ARAN vanCalibrated using dipstick measurements
83
Flow Number vs. Rate of Rutting
0 200 400 600 800 1000 1200 1400 1600 1800 20000.0
1.0
2.0
3.0
4.0
5.0
6.0f(x) = 34926.8365793956 x^-1.76366311382016R² = 0.762098329966824
Flow Number
Rate
of R
utting
, mm
/mill
ion
ESAL
s
84
Proposed Fn Criteria (50% Reliability)
Traffic Level Maximum Allowable Rut Depth
(Million ESALs) 9.5 mm 12.5 mm
<3 196 cycles 168 cycles
3 - <10 387 cycles 332 cycles
10 - <30 722 cycles 618 cycles
>=30 1429 cycles 1223 cycles
85
Two BBFT ProceduresAASHTO T 321 ASTM D 7460
30% Sulfur - Rich Bottom - Normalized Modulus Data
0
200
400
600
800
1000
1200
1400
1600
0 50000 100000 150000 200000 250000
Cycles to FailureN
orm
aliz
ed M
odul
us x
Cyc
les
Maximum Modulus x Cycles = Failure Point
S1SP ARA0127-86
Mechanistic Design:Implementation of MEPDG
AAPA Study TourFHWA Turner-Fairbank Center
August 12, 2010
H. L. Von Quintus, P.E.
Expanding the Realm of Possibility87
Implementation Effort; Plan is to Adopt MEPDG at Some Level
PCC
Presently, 50% of AgenciesPlan to Adopt the MEPDG.
PCC
Expanding the Realm of Possibility
Issue: Lab Testing EquipmentMany agencies do not have & do not plan to purchase equipment to test materials.
Expanding the Realm of Possibility89
Solution: Build Material Libraries
Expanding the Realm of Possibility
Many agencies have not maintained their weighing in motion equipment.
Issue: Traffic Characterization
Solution;Use LTPP & other
Data Sources
Expanding the Realm of Possibility
The Future:Integration of structural design, mixture design,
& QA
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Status of PP Design Implementation
• Only 1 DOT has a formal PP design processo Design strain 63 o Mean monthly pavement temperature for the hottest month
• MEPDGo Software will be modified to include the endurance limit by keeping
tally of the loads that exceeded the limit and outputting that quantity or percentage.”
o “The use of an endurance limit greater than 100 microstrain may be highly related to the use of modified binders……. The use of modified binders may require model recalibration.”
• PerRoado Developed by NCATo Supported by NAPAo Not a formally recognised design procedure.
www.aapa.asn.au
PerRoad 3.5• Sponsored by APA• Developed at Auburn University / NCAT• M-E Perpetual Pavement Design and Analysis Tool
Environmental Conditions
Layer Definitions
Variability and Thresholds
Thickness
f
Material Properties
f
Location in Layer
Pavement Response
Threshold
Transfer Function
Performance Criteria
Traffic Volume
Types of Axles
Axle Weight Distribution
Functional Classification
Vehicle FrequencyNumber of Axles
Percent B
elow Threshold
Damage Accumulatio
n
Design “L
ife”
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Personal notes
• A study tour is a great way to learn and share information
• Builds trust between owner/contactor• Asphalt FEL is a proven concept• Predictive models for material characteristics
are reliable provided they are calibrated • Many practical design issues to be refined; mix
materials, interface bond, compaction to name but a few
www.aapa.asn.au
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Conclusions• Fatigue Endurance Limit is an accepted concept• If the pavement structure is sufficiently thick so that
the FEL is not exceeded and long life or so called ‘perpetual pavement’ becomes a reality
• Thickness design methods in the USA are moving away from WMAPT towards using dynamic modulus at a selected range of temperatures to match seasonal effects.
• The USA MEPDG is being upgraded to include the fatigue endurance limit concept.
• NCAT have been developing a software program (called PerRoad and PerRoad Express) to assist in the design of perpetual pavements.
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Recommendations• Australian flexible pavement design practice should
investigate opportunities for inclusion of Fatigue Endurance Limits into local practice.
• Existing laboratory tools in Australia should be used to facilitate comparison of local products to allow comparison with USA materials proven on their major highways and accelerated test facilities.
• A ‘library’ of the performance of Australian pavement materials should be developed to provide input into local predictive models.
• AAPA should ‘partner’ with SRA / ARRB / consulting fraternity on the modification of Australian design methods to include PP design concepts in pavement design systems and design tools.
AAPA 2010 Study Tour – Perpetual Pavement Concepts
TMR PP Efforts
AAPA 2010 Study Tour – Perpetual Pavement Concepts
Personal notes
PERPETUAL PAVEMENT REALISATION DEMANDS EXEMPLORY CONSTRUCTION STANDARDS
Thank you
www.aapa.asn.au
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