Perpetual Pavement Concepts

AAPA 2010 Study Tour – Perpetual Pavement Concepts

Perpetual Pavement Concepts

Ian Rickards | Jason Jones |Russell ClaytonGreg Stephenson | Young Choi


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


Sessions

• University of CaliforniaoCarl Monismith

• NAPA – Asphalt Pavement AllianceoDavid Newcomb

• University of IllinoisoMarshall Thompson

• National Centre for Asphalt TechnologyoDavid Timm

www.aapa.asn.au


What is a Perpetual Pavement?• No deep structural distress



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


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


{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


Top-Down Cracking


Perpetual Pavements• Resist Structural DistressesoFatigue CrackingoRutting

• Withstand Climate and TrafficoDesign for Subgrade ModulusoUse Strong FoundationoMix DesignoMaterials Selection


Materials• FoundationoNot Much ChangeoSoilsoGranular MaterialsoStabilization

• Asphalt Materials and Mix DesignoBase Layero Intermediate LayeroWearing Course


› 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


Construction• Foundation requirements for construction• Interlayer friction• Density – especially in asphalt base layer• Overly stiff mixtures• Segregation• Joint density• Asphalt layer bonding• QC/QA


Interlayer Bonding

• Ensure complete tack coverage• Use trackless or polymer modified or hot tack• Keep traffic to a minimum


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


M-E Perpetual Pavement Design

No Damage Accumulation

Log N

Log e

ThresholdStrainE1

E2

E3

D1

D2

D3

P

A

et

ev


Fatigue Endurance Limit

• Definition:o The stress or strain level below which no fatigue

damage originating from the bottom of the pavement occurs.


SHRP Fatigue Test Equipment


AustralianBeam Fatigue Apparatus(based on SHRP equip.)


FATIGUE TESTING

• Tensile Strain in Flexural Beam Testo Other Configurations

o 10 Hz Haversine Load, 20o C, Controlled Strain


HMA FATIGUE

N (LOG)

e AC (L

OG

)N = K1 (1 / eAC)K2

FATIGUE DAMAGE

ENDURANCE LIMIT

NO FATIGUE DAMAGE


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)



• 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


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


Stra

in, (

10E

-06)

Endurance Limit

0

200

400

600

800

1000

1200

1000 100000 10000000 1.1E+08


Stra

in, (

10E

-06)

Endurance Limit

Normal Range forFatigue Testing



• 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


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



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




31

Field Strain Measurements (1/2)Direction of TravelDirection of TravelDirection of Travel


Strain Measurements


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


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


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


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


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


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


|E*|

, ksi

10

100

1,000

10,000


|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


Many agencies have not maintained their weighing in motion equipment.

Issue: Traffic Characterization

Solution;Use LTPP & other

Data Sources


The Future:Integration of structural design, mixture design,

& QA


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”


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


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.


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.


TMR PP Efforts


Personal notes

PERPETUAL PAVEMENT REALISATION DEMANDS EXEMPLORY CONSTRUCTION STANDARDS

Thank you

www.aapa.asn.au

http://en.wikipedia.org/wiki/File:Flag_of_the_United_States.svg

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