The Future of Asphalt The Future of Asphalt Pavement Structural & Pavement Structural &

Mixture DesignMixture DesignComplex Modulus, /E*/Complex Modulus, /E*/

Thomas HarmanThomas HarmanAsphalt Pavement Team Leader, R&DAsphalt Pavement Team Leader, R&DFederal Highway AdministrationFederal Highway Administration

www.TFHRC.www.TFHRC.govgov

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I N D U S T R YSUPERPAVE 2005

Materials

Structural

Construction

FutureFuture

PRS / Warranty

2002 Guide

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SUPERPAVE 2005Superpave II

The PlayersThe Players

NCHRP 1NCHRP 1--37A37A•• Recommend Test(s)Recommend Test(s)

SPRSPR--0003(84)0003(84)•• E* Pooled FundE* Pooled Fund

•• Evaluate Test Evaluate Test ProceduresProcedures

NCHRP 9NCHRP 9--1919•• Recommend Test(s)Recommend Test(s)

NCHRP 9NCHRP 9--2929•• Equipment SpecsEquipment Specs

•• First Articles First Articles EvalEval•• Revise SpecsRevise Specs

2002 Guide

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SUPERPAVE 2005Superpave II

Simple Performance Test for Simple Performance Test for Superpave Mix DesignSuperpave Mix Design

Advanced Asphalt Technologies, LLC

“Engineering Services for the Asphalt Industry”

SPT What Is It?SPT What Is It?

Test(s) that indicates how mix will Test(s) that indicates how mix will performperform–– RuttingRutting–– Cracking Cracking

SPTSPTRequirementsRequirements

•• Absolute Requirements of TestAbsolute Requirements of Test–– Compliment Superpave Volumetric DesignCompliment Superpave Volumetric Design–– Use Gyratory SpecimensUse Gyratory Specimens–– High Correlation to Rutting/FractureHigh Correlation to Rutting/Fracture–– Identify Inferior MixesIdentify Inferior Mixes

•• Preferred Requirements of TestPreferred Requirements of Test–– Tied to Structural Design Tied to Structural Design –– Adaptable to QC/QAAdaptable to QC/QA

Project 9Project 9--19 19 Candidate TestsCandidate Tests

•• Complex Modulus, /E*/Complex Modulus, /E*/–– RuttingRutting–– CrackingCracking

•• Creep Test, FTCreep Test, FT–– RuttingRutting

•• Repeated Load Test, FNRepeated Load Test, FN–– RuttingRutting

Project 9Project 9--19 19 Correlation StudyCorrelation Study

MnRoad

WesTrack FHWA-ALF

ALF: Rut Depth vs. E*max/sinφ @ 130 °F (54.4 °C)

Se/Sy = 0.35R2=0.90

0

10

20

30

40

50

60

0 0.05 0.1 0.15 0.2 0.25

E*max/sinφ (10^6 psi)

Rut

Dep

th @

10,

000

Pas

ses

(mm

)

5 - AC-10

7 - Styrelf

8 - Novophalt

9 - AC-5

10 - AC-20

11 - Base AC-5

12 - Base AC-20

Unconfined -- Linear Range

Complex Modulus, /E*/Complex Modulus, /E*/

0

0*εσ

=E

Stress

Strain

Time

•• RuttingRutting–– Min |E*| at High TempMin |E*| at High Temp

•• Fatigue CrackingFatigue Cracking–– Max |E*| at Intermediate TempMax |E*| at Intermediate Temp

Creep Flow Time, FTCreep Flow Time, FT

ST

RA

IN

Flow Time

TIMES

TR

ES

S

•• RuttingRutting–– Min FT at High TempMin FT at High Temp

Repeated Load Permanent Repeated Load Permanent Deformation Test, Flow NumberDeformation Test, Flow Number

•• RuttingRutting–– Min FN at High TempMin FN at High Temp

ST

RA

IN

Flow Number

TIMES

TR

ES

S

AAdvantagesdvantages

•• Complex Modulus, /E*/Complex Modulus, /E*/–– Used for Structural Design in 2002 PDGUsed for Structural Design in 2002 PDG–– Addresses Rutting and Cracking Addresses Rutting and Cracking

•• Creep, FTCreep, FT–– Simple Test EquipmentSimple Test Equipment–– Minimal TrainingMinimal Training

•• Repeated Load, FNRepeated Load, FN–– Potentially Best Simulation of Actual LoadingPotentially Best Simulation of Actual Loading

DDisadvantageisadvantage

•• Specimen SizeSpecimen Size–– 1:1.5 D/H Ratio required to ensure 1:1.5 D/H Ratio required to ensure

fundamental propertiesfundamental properties–– 100 mm Diameter by 150 mm High100 mm Diameter by 150 mm High–– Smooth Parallel Ends (Sawed)Smooth Parallel Ends (Sawed)

•• Sawed and Cored From OverSawed and Cored From Over--Height Gyratory SpecimensHeight Gyratory Specimens–– Not all SGC can produced Not all SGC can produced

SpecimensSpecimens

Project 9Project 9--19 19 SPT Criteria DevelopmentSPT Criteria Development

•• Use Models proposed in 1Use Models proposed in 1--37A, account for:37A, account for:–– ClimateClimate–– Traffic LevelTraffic Level–– StructureStructure

•• Test at Effective Pavement TemperatureTest at Effective Pavement Temperature–– Minimum or Maximum ValuesMinimum or Maximum Values

•• Traffic LevelTraffic Level•• Pavement StructurePavement Structure

•• Completed in Fall 2002Completed in Fall 2002

Project 9Project 9--19 Validation19 Validation

•• Criteria Will Be ValidatedCriteria Will Be Validated–– Not the testsNot the tests

•• InIn--Service Pavement DataService Pavement Data–– 50+ LTPP and Other Test 50+ LTPP and Other Test

SectionsSections

•• Completed in 2002Completed in 2002

Project 9Project 9--2929Equipment SpecificationsEquipment Specifications

•• Simple Performance Test SystemSimple Performance Test System–– All 3 TestsAll 3 Tests

•• Automated Specimen Fabrication Equipment…Automated Specimen Fabrication Equipment…

•• Encourage Innovation by ManufacturersEncourage Innovation by Manufacturers–– User FriendlinessUser Friendliness–– ReliabilityReliability–– CostCost

Project 9Project 9--29 29 Specification DevelopmentSpecification Development

Draft Equipment SpecsCost Estimate

Manufacturer’s Review

First Article Equipment SpecsRevised Estimate

User’s Workshop Ideas

Research Test Protocols

First Article SPTFirst Article SPTProcurementProcurement

•• EnduraTecEnduraTec•• InstronInstron•• InterlakenInterlaken•• ShedworksShedworks

• Specifications• Advantages• Cost• Past Performance

First Article SPT SystemsFirst Article SPT Systems

•• TestsTests–– Complex ModulusComplex Modulus–– Flow TimeFlow Time–– Flow NumberFlow Number

•• Temperature RangeTemperature Range–– 20 to 60 °C20 to 60 °C

•• Confining Pressure RangeConfining Pressure Range–– 0 to 210 kPa0 to 210 kPa

First Article First Article Simple Performance Test SystemsSimple Performance Test Systems

SHEDWORKS

INTERLAKEN

InstrumentationInstrumentationLVDT’sLVDT’s

ShedworksShedworks

InterlakenInterlaken

Specimen Fabrication SystemSpecimen Fabrication System

•• Pine Pine •• ShedworksShedworks • Specifications

• Automated• Cost

First Article First Article Specimen Fabrication SystemSpecimen Fabrication System

First Article First Article Specimen Fabrication EquipmentSpecimen Fabrication Equipment

CORE BARREL

BLADES

CHUCK

SummarySummary-- Simple Performance Test Simple Performance Test Work CompletedWork Completed

•• Three Candidate TestsThree Candidate Tests•• Detailed Draft ProtocolsDetailed Draft Protocols•• Detailed Equipment SpecificationsDetailed Equipment Specifications•• First Article DevicesFirst Article Devices

–– Simple Performance Test System Simple Performance Test System ($25 k to $45 k)($25 k to $45 k)

–– Automated Specimen Fabrication System Automated Specimen Fabrication System ($12 k)($12 k)

NCHRP 9NCHRP 9--2929TimelineTimeline

•• Criteria DevelopmentCriteria Development–– Early Fall 2002Early Fall 2002

•• Criteria ValidationCriteria Validation–– End of 2002End of 2002

•• First Article EvaluationFirst Article Evaluation–– Early 2003Early 2003

Complex Modulus, /E*/ for Complex Modulus, /E*/ for Structural DesignStructural Design

-80

-70

-60

-50

-40

-30

-20

-10

0

Time (sec.)

Str

ess

(kP

a)

25 Hz, 68.90 kPa, 200 Cycles

10 Hz, 62.01 kPa, 200 Cycles

5 Hz, 55.12 kPa, 100 Cycles

1 Hz, 48.23 kPa, 50 Cycles

0.5 Hz, 42.34 kPa, 20 Cycles

0.1 Hz, 34.45 kPa, 20 Cycles

180 seconds rest period between frequencies

2002 PDG Requires a 2002 PDG Requires a Range of Frequencies & Temp.’sRange of Frequencies & Temp.’s

10

-70

-60

-50

-40

-30

-20

-10

0398 398.1 398.2 398.3 398.4 398.5 398.6 398.7 398.8

Time (sec.)

Stre

ss (

kPa)

ExampleExample10 Hz and 62 10 Hz and 62 kPakPa

/E*/ Pooled Fund Study /E*/ Pooled Fund Study ––UConnUConn (2002 PDG)… (2002 PDG)… Perliminary Result of Round Robin Study

100

1000

10000

25 10 5 1 0.5 0.1 25 10 5 1 0.5 0.1 25 10 5 1 0.5 0.1

Frequency, Hz

E*,

MP

a

MDNCAATFHWA

21°C

38° C

54° C

Understanding Modified BindersUnderstanding Modified BindersNCHRP 90NCHRP 90--07, TPF 5(019)07, TPF 5(019)

FHWAFHWA--ALF ALF Mean and Standard Deviation of /E*/Mean and Standard Deviation of /E*/

(3 Replicates, 50(3 Replicates, 50°°C, 10 Hz)C, 10 Hz)

0

200

400

600

800

1000

1200

1400

1600

1800

EVA

CMCR

A ESL

SBS L

Air Blow

nEV

AG

PG 70

-22

SBS R

G

SBS L

G

Elvalo

y

PG 64

-28

E*,

MP

a

Mean

Std

FHWAFHWA--ALFALFCoefficient of Variation of /E*/Coefficient of Variation of /E*/

(3 Replicates, 50(3 Replicates, 50°°C, 10 Hz)C, 10 Hz)

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

EVA

CMCR

AES

LSB

S L

Air Blow

nEV

AG

PG 70

-22

SBS R

G

SBS L

G

Elvalo

y

PG 64

-28

%C

V

TRB Superpave TRB Superpave Binder Expert Task GroupBinder Expert Task Group

üü /E*/ Concern/E*/ Concern

AASHTO/ TRB / NCHRP / FHWA

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

Elvaloy PG64 SBS L SBSLG

PG70 AB SBSRG

EVA G ESI CRA EVA

Dyn

amic

Mod

ulus

, IE

*I, G

Pa

Lab Mix Lab Mix –– Similar PG GradeSimilar PG Grade/E*/ at 10 Hz/E*/ at 10 Hz

0

100

200

300

400

500

600

Elvaloy CRA SBS LG EVA PG64 PG70 SBSRG

ESI SBS L AB EVA G

Cha

nge

in S

train

, ∆

ε, M

icro

Stra

inPermanent StrainPermanent Strain

25 to 0.1 Hz25 to 0.1 Hz

10000

15000

20000

25000

30000

1.0 1.1 1.2 1.3 1.4 1.5

/E*/, GPa (Simple Performance Test)

Acc

umul

ativ

e St

rain

(Si

mpl

e Sh

ear

Tes

t)

ElvaloySBSLSBSLGPG70ABSBSRGESICRA

SST SST vs vs /E*//E*/

0.0

0.2

0.4

0.6

0.8

1.0

0.0 0.2 0.4 0.6 0.8 1.0

Normalized Weighted Complex Modulus

Nor

mal

ized

SST

Per

man

ent D

efor

mat

ion

ElvaloySBSLSBSLGPG70ABSBSRGESICRA

/E*/ x (/E*/ x (?? ??maxmax / / ?? ??))

SummarySummary

NCHRP 1NCHRP 1--37A37A•• Complex Modulus, /E*/Complex Modulus, /E*/•• Issues of repeatabilityIssues of repeatability

•• Concern with modifiersConcern with modifiers

NCHRP 9NCHRP 9--19/2919/29•• Links Mix Design to Links Mix Design to

Structural DesignStructural Design

2002 Guide

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SUPERPAVE 2005Superpave II

SmoothRoads Ahead