Michigan Asphalt Conference2016

Perpetual Pavement DesignAn Introduction to the PerRoad

Program

Dave TimmAuburn University / NCAT

Dave NewcombTexas A&M Transportation Institute

Overview

Pavement design background Layered elastic theory

Perpetual pavement design philosophy Sensitivity Study

Program basics Example problems Design simulations

WHY ARE PERPETUAL PAVEMENTS IMPORTANT?

Perpetual Pavement Award Started by the Asphalt Pavement Alliance in 2001. Road must be >35 years old. No thickness increase >4 inches. No overlay interval less than 13 years. Nominated by DOT.

Washington State Performance

0

200

400

600

800

1000

0 - 10 11 - 20 21 - 30 31 - 40 41 - 50 51 - 60 61 or More

Age (Years)

Lane

Mile

s

HMA (Lane Miles)PCCP (Lane Miles)

Washington State Performance

0

200

400

600

800

1000

1200

0.0 - 0.5 0.5 - 1.0 1.0 - 1.5 1.5 - 2.0 2.0 - 2.5 2.5 - 3.0 3.0 - 3.5 3.5 - 4.0 4.0 - 4.5 4.5 - 5.0 5.0 orMore

IRI (m/km)

Lane

Mile

s

HMA (Lane Miles)PCCP (Lane Miles)

Description PSR Rating IRI NHS Ride Quality

Very Good 4.0 170 in/mi)

Less than Acceptable (>2.7 m/km)

Material Usage

Save 32% Save 28%

Save 31% Save 28%

Chart1

9346

6732

HMA, tons

Sheet1

Conv.Perp. Pvmt.

93466732

Chart1

2337

1683

RAP, tons

Sheet1

Conv.Perp. Pvmt.

23371683

Chart1

9827

6698

Aggregate, tons

Sheet1

Conv.Perp. Pvmt.

98276698

Chart1

350

252

Binder, tons

Sheet1

Conv.Perp. Pvmt.

350252

Perpetual Pavement versusConventional Design

Chart1

7.259

10.511

15.2512.5

18.7513.5

20.514

22.514

AASHTO

PerRoad

Traffic, ESAL

HMA Thickness, in.

Sheet1

0.111050100200

AASHTO7.2510.515.2518.7520.522.5

PerRoad91112.513.51414

A City in Texas Asphalt Performance Problems Ban Asphalt?

9

A City in Texas

Goal of Perpetual Pavement Design Design the structure such that there are no deep

structural distresses Bottom up fatigue cracking Structural rutting

All distresses can be quickly remedied from surface

Result in a structure with Perpetual or Long Life

Avoid These!

April 21, 2014 Panel Briefing 11

Bottom-Up Fatigue

Structural Rutting

Surface Distresses Only

Non-Structural Rutting

Top Down Cracking

Pavement Design: Where were we?

Using 1960s performance equations 1950s type of load Thin pavement structures (Max. 6 HMA) Meaning of structural coefficients Limited reliability analysis Some movement to M-E

AASHO Road Test

Trucks

M-E Design Framework

WESLEA ,

Transfer Function(s)

f

Structural Parameters

Load Configurations

=i

i

NfnDn

D>1?

D

1 2 3

BeforeLoading During

Loading

AfterLoading -

Same Sizeas BeforeLoading

How an Elastic Material Behaves.

Dynamic Modulus Test

HMA Modulus VersusTemperature

10

100

1000

10000

0 20 40 60 80 100 120

Temperature, F

Mod

ulus

, 100

0 ps

i

Soil Modulus Testing

Effect of Moisture Content

1

10

100

0 5 10 15 20

Moisture Content, %

Mod

ulus

, ksi

M-E Design Framework

WESLEA ,

Transfer Function(s)

f

Structural Parameters

Load Configurations

=i

i

NfnDn

D>1?

D

M-E Design Framework

WESLEA ,

Transfer Function(s)

f

Structural Parameters

Load Configurations

=i

i

NfnDn

D>1?

D

Layer 1HMA

E1Layer 2

Granular BaseE2

Layer 3Subgrade Soil

E3

h1

h2

No bottom boundary, assume soil goes on infinitely.

Nohorizontalboundary, assumelayersextendinfinitely.

Tire has a total load P, spread over a circulararea with a radius of a, resulting in a contactpressure of p.

PavementReactions

Deflection ()

Tensile Strain (t)

Compressive Strain (v)

Three Layer Systems

M-E Design Framework

WESLEA ,

Transfer Function(s)

f

Structural Parameters

Load Configurations

=i

i

NfnDn

D>1?

D

Fatigue Transfer Function

Horiz

onta

l Ten

sile

Stra

in ( i

n./in

.10

)

Load Applications (N )f

3

10 10 10 10 10 103 4 5 6 7 8

10

100

1,000

10,000

log N = 15.947 - 3.291 log ( ) - 0.854 log ( )f t

10-6

E

10

-6

E = 200,000 psi(1,380 MPa)

E = 500,000 psi(3,450 MPa)

-6

Horizontal Tensile Strain ( in./in.10 )

f

f

3

E

10

Load Applications (N )

log N = 15.947 - 3.291 log ( ) - 0.854 log ( )

E = 200,000 psi

(1,380 MPa)

(3,450 MPa)

E = 500,000 psi

-6

10

t

10,000

1,000

100

10

8

7

6

5

4

3

10

10

10

10

10

10

Rutting Transfer Function

Ver

tical

Com

pres

sive

Stra

in (

in./i

n. 1

0 )

N = 1.077 x 10 ()

10 10 10 10 10 103 4 5 6 7 8100

1,000

10,00

100,00

f

-6

4.484310 v

Load Applications (N )

18

f

-6

-6

Vertical Compressive Strain ( in./in. 10 )

v

-6

N = 1.077 x 10 ()

18

10

4.4843

f

Load Applications (N )

f

100,000

10,000

1,000

100

8

7

6

5

4

3

10

10

10

10

10

10

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

M-E Design Framework

WESLEA ,

Transfer Function(s)

f

Structural Parameters

Load Configurations

=i

i

NfnDn

D>1?

D

Structural/Performance Analysis Initial trial design

Initial estimate of layer thickness Required repairs to the existing pavement Pavement materials characterization

Analyzed by cumulative damage incrementally over time using Structural response Performance models

Perpetual Pavement Design

No Damage Accumulation

Log N

Log

ThresholdStrain

Tandem Axles

0

5

10

15

20

25

30

35

40

0 10 20 30 40 50 60 70 80Axle Group Weight, kip

Axl

es /

1000

Hea

vy A

xles

0 50 100 150 200 250 300 350

Axle Group Weight, kN

Rural InterstateRural Principal ArterialRural Minor ArterialRural Major CollectorRural Minor CollectorRural Local CollectorUrban InterstateUrban Other Freeways and ExpresswaysUrban Principal ArterialUrban Minor ArterialUrban Collector

PerRoad 3.3 Sponsored by APA Developed at Auburn University / NCAT M-E Perpetual Pavement Design and Analysis Tool

Coming Refinement Currently a single fatigue endurance limit is used. Results in one-size fits all overly conservative Use FEL Ratio. Use distribution of strains.

Ratio = FELn/FELlab

April 21, 2014 Panel Briefing 39

PerRoadXPress

Vehicle Type Distributions

PerRoadXPress

DownloadPerRoad 3.3

AndPerRoadXpress

Free!

Go To:www.asphaltroads.org

ORGoogle David Timm at Auburn University

www.asphalttechnology.org/membership

At the 2016 AAPT Meeting:

Leading Edge Workshop: Cracking Tests 5 Presentations on Cracking Tests Symposium: Balanced Mix Design 5 Presentations on High RAP/RAS Implementation of Specifications Aging Behavior Forum Topic: World Asphalt Market

Perpetual Pavement DesignAn Introduction to the PerRoad ProgramOverviewWhy are Perpetual Pavements Important?Perpetual Pavement AwardWashington State PerformanceWashington State PerformanceMaterial UsagePerpetual Pavement versusConventional DesignA City in TexasGoal of Perpetual Pavement DesignAvoid These!Surface Distresses OnlyPavement Design: Where were we?Slide Number 14Slide Number 15Slide Number 16Dynamic Modulus TestHMA Modulus VersusTemperatureSlide Number 19Soil Modulus TestingEffect of Moisture ContentSlide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Fatigue Transfer FunctionRutting Transfer FunctionSlide Number 29Slide Number 30Structural/Performance AnalysisPerpetual Pavement DesignSlide Number 33PerRoad 3.3Slide Number 35Slide Number 36Slide Number 37Slide Number 38Coming RefinementPerRoadXPressVehicle Type DistributionsPerRoadXPressSlide Number 43Slide Number 44At the 2016 AAPT Meeting: