Superpave-PG BinderGrading.pdf

8/17/2019 Superpave-PG BinderGrading.pdf

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October 30, 2003 T3S - Superpave for Low Volume Roads - R. Horan 1

Performance GradedPerformance Graded

Asphalt BindersAsphalt BindersBob Horan, P.E.

Consulting EngineerMechanicsville, VA


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What is Asphalt?What is Asphalt?


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The 3 A’s of Hot Mix AsphaltThe 3 A’s of Hot Mix Asphalt

Aggregates,Aggregates,Asphalt,Asphalt,

HMA = Asphalt + Aggregates + AirHMA = Asphalt + Aggregates + Air

and Airand Air


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Asphalt OverviewAsphalt Overview

•• TerminologyTerminology

•• HistoryHistory

•• UsesUses

•• BackgroundBackground

•• Asphalt Behavior Asphalt Behavior •• Classification (Grading) of AsphaltClassification (Grading) of Asphalt

•• Asphalt ModificationAsphalt Modification


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•• Called different thingsCalled different things

– – BitumenBitumen

– – AsphaltAsphalt

– – Liquid AsphaltLiquid Asphalt

– – Asphalt CementAsphalt Cement

– – Asphalt BinderAsphalt Binder

– – BinderBinder

… But mean basically the same thing!… But mean basically the same thing!


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BackgroundBackground

•• AsphaltAsphalt

– – Soluble in petroleumSoluble in petroleum

productsproducts

– – Generally a byGenerally a by--product of petroleumproduct of petroleum

distillation processdistillation process

– – Can be naturallyCan be naturally

occurringoccurring

•• TarTar

– – Resistant toResistant to

petroleum productspetroleum products

– – Generally byGenerally by--product of cokeproduct of coke

(from coal)(from coal)

productionproduction



AsphaltAsphalt -- Definition:Definition:

“A dark brown to black cementitious“A dark brown to black cementitious

material in which the predominatingmaterial in which the predominating

constituents are bitumens whichconstituents are bitumens which

occur in nature or are obtained inoccur in nature or are obtained inpetroleum processing.”petroleum processing.”

(ASTM D8)(ASTM D8)






•• UsesUses






Brief HistoryBrief History

•• 32003200 -- 540 B. C.540 B. C. Extensive use inExtensive use in MesapotamiaMesapotamia andandIndus Valley as cement for masonry andIndus Valley as cement for masonry andstreet construction and as waterproofingstreet construction and as waterproofing

agentagent•• 300 B.C.300 B.C. Used for mummification in EgyptUsed for mummification in Egypt

•• 18701870 First asphalt pavement laid in Newark,First asphalt pavement laid in Newark,

New JerseyNew Jersey•• 11876876 First sheet asphalt pavement laid inFirst sheet asphalt pavement laid in

Washington, DC with imported lakeWashington, DC with imported lake

asphaltasphalt•• 19021902 Approx. 20,000 tons of asphalt refinedApprox. 20,000 tons of asphalt refined

from petroleum in United Statesfrom petroleum in United States

•• NowNow Over 30,000,000 tons produced in U.S.Over 30,000,000 tons produced in U.S.






•• UsesUses



••

Asphalt ModificationAsphalt Modification



•• Refining produces asphalt withRefining produces asphalt with

specific characteristics forspecific characteristics for

varied usesvaried uses

– – Paving asphaltPaving asphalt

– – Roofing asphaltRoofing asphalt

– – Other special usesOther special uses•• WaterproofingWaterproofing

•• SealingSealing

Asphalt SourcesAsphalt Sources


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•• UsesUses



••

Asphalt ModificationAsphalt Modification


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Sources of AsphaltSources of Asphalt

•• Natural asphalt depositsNatural asphalt deposits

•• Petroleum asphaltsPetroleum asphalts


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Asphalt TypesAsphalt Types

•• Natural asphalt depositsNatural asphalt deposits

– – Natural evaporation of volatileNatural evaporation of volatileportions of petroleum leaving theportions of petroleum leaving the

asphalt fractionsasphalt fractions

– – Lake asphaltLake asphalt•• TrinidadTrinidad

•• BermudezBermudez

– – Rock asphaltRock asphalt

•• Natural asphalt deposits in porous rock Natural asphalt deposits in porous rock


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Trinidad Lake AsphaltTrinidad Lake Asphalt


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BackgroundBackground

•• Each lake asphalt source veryEach lake asphalt source veryconsistentconsistent

– – Used solubility test to determine sourceUsed solubility test to determine source

•• Insolubles differed substantially betweenInsolubles differed substantially between

sourcessources

•• Demand for paved roads exceeded theDemand for paved roads exceeded thesupply of lake asphalts in late 1800’ssupply of lake asphalts in late 1800’s

– – Led to use of petroleum asphaltsLed to use of petroleum asphalts


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Asphalt is one of the products of the petroleum industryAsphalt is one of the products of the petroleum industry

Petroleum AsphaltPetroleum Asphalt


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PetroleumPetroleum--Based AsphaltsBased Asphalts

•• Asphalt is waste product fromAsphalt is waste product from

refinery processing of crude oilrefinery processing of crude oil

– – Sometimes called the “bottom of theSometimes called the “bottom of the

barrel”barrel”

•• Properties depend on:Properties depend on: – – Refinery operationsRefinery operations

– – Composition crude which areComposition crude which aresourcesource--dependentdependent

GasolineGasoline

KeroseneKerosene

Lt. Gas OilLt. Gas OilDieselDiesel

Motor OilsMotor Oils

Burner FuelBurner FuelAsphaltAsphalt

Barrel of Crude OilBarrel of Crude Oil


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Refinery OperationRefinery Operation

FIELD STORAGE

PUMPING

STATION

LIGHT DISTILLATE

HEAVY DISTILLATE

PROCESSUNIT

ASPHALTCEMENTS

FOR PROCESSING INTO

EMULSIFIED AND

CUTBACK ASPHALTS

STILL

AIR

AIRBLOWNASPHALT

STORAGE

TOWERDISTILLATIONREFINERY

RESIDUUM

OR

GAS

PETROLEUM

SAND AND WATER

CONDENSERSANDCOOLERS

TUBEHEATER

MEDIUM DISTILLATE


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•• UsesUses





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Asphalt Binder Behavior Asphalt Binder Behavior

– – TemperatureTemperature

– – Time of LoadingTime of Loading

– – Aging is alsoAging is alsoimportantimportant


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Asphalt Binder BehaviorAsphalt Binder Behavior

Consistency Consistency

LiquidLiquid

SemiSemi--SolidSolid

TemperatureTemperature

Asphalt is a Asphalt is a thermoplastic thermoplastic materialmaterial

that softens as it is heated andthat softens as it is heated andhardens when cooled.hardens when cooled.


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Temperature, °CTemperature, °C

Stiffness (Response to Load)Stiffness (Response to Load)

--3030 2525 6060 135135

elasticelastic

viscousviscous

elasticelastic

solid solid

viscousviscous

fluid fluid

?

Asphalt has Viscoelastic Properties

Asphalt Binder Behavior Asphalt Binder Behavior


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60 C60 C

25 C25 C

1 hour1 hour

1 hour1 hour

Time versus TemperatureTime versus Temperature

10 hours10 hours

Flow

Asphalt Binder BehaviorAsphalt Binder Behavior

(MS(MS--22, Fig. 2.03)22, Fig. 2.03)


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Binder BehaviorBinder Behavior -- AgingAging

•• Asphalt Reacts with OxygenAsphalt Reacts with Oxygen – – Long and ShortLong and ShortTermTerm

– – “oxidative” or “age” hardening“oxidative” or “age” hardening•• During ConstructionDuring Construction -- Short TermShort Term

– – hot mixinghot mixing

– – placing/compaction placing/compaction

•• In ServiceIn Service -- Long TermLong Term

– – hot climate worse than cool climatehot climate worse than cool climate

– – summer worse than winter summer worse than winter

•• VolatilizationVolatilization-- Short TermShort Term

– – volatile components evaporate during constructionvolatile components evaporate during construction


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•• UsesUses





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Early SpecificationsEarly Specifications

•• Lake AsphaltsLake Asphalts

– – AppearanceAppearance – – Solubility in carbon disulfideSolubility in carbon disulfide

•• Petroleum asphalts (early 1900’s)Petroleum asphalts (early 1900’s) – – ConsistencyConsistency

•• ChewingChewing

•• Penetration machinePenetration machine

– – Measure consistencyMeasure consistency


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ViscosityViscosity

100 g100 g 100 g100 g

penetrationpenetration

0 sec0 sec5 sec5 sec

Penetration GradingPenetration Grading

Typical Pen Grades

85-100 • 120-150


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ViscosityViscosity

vacuumvacuum

Typical Vis Grades

AC - 20 • AC - 10

Viscosity GradingViscosity Grading


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2525 6060 135135--1515

“Stiffness” of three different asphalts“Stiffness” of three different asphalts

hardhard

softsoft

penpen

AABB

CC

Temperature, CTemperature, C

Penetration TestPenetration Test


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2525 6060 135135--1515

hardhard

softsoft

penpenvisvis

visvis

AABB

CC

Temperature, CTemperature, C

Penetration andPenetration and

Viscosity TestViscosity Test

“Stiffness” of three different asphalts“Stiffness” of three different asphalts


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Problems with Current SystemProblems with Current System

•• ViscosityViscosity

– – viscous effects only at 60 Cviscous effects only at 60 C

•• PenetrationPenetration

– – empirical consistency only at 25 Cempirical consistency only at 25 C

•• No Low Temperature PropertiesNo Low Temperature Properties

MeasuredMeasured


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Problems with Current SystemProblems with Current System

•• Problems with Modified AsphaltProblems with Modified Asphalt

CharacterizationCharacterization

•• Specification ProliferationSpecification Proliferation

•• Long Term Aging not ConsideredLong Term Aging not Considered


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•• UsesUses





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Why Modify Asphalt?Why Modify Asphalt?

•• Change effects of temperature andChange effects of temperature and

loading on physical properties of asphaltloading on physical properties of asphalt

•• Provides a “stiffer” binder at highProvides a “stiffer” binder at high

temperatures (higher PG binder grade)temperatures (higher PG binder grade)

•• Reduce effects of aging/oxidation onReduce effects of aging/oxidation on

asphalt propertiesasphalt properties

•• Improve adhesion to aggregatesImprove adhesion to aggregates


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Modified PG BindersModified PG Binders

•• Many different types of modified bindersMany different types of modified binders

– – elastomers (Stylink, Citgoflex, others)elastomers (Stylink, Citgoflex, others) --SBS,SBR SBS,SBR

– – plastomers (Novophalt, Vestoplast, others)plastomers (Novophalt, Vestoplast, others)

– – gelled (Multigrade)gelled (Multigrade)

– – blown, oxidizedblown, oxidized•• Little performance history with someLittle performance history with some

modifiersmodifiers

•• Use of modified binder grades will increaseUse of modified binder grades will increase

cost (materials cost $2cost (materials cost $2 -- $5/ton of mix)$5/ton of mix)

•• Is it worth the extra cost?Is it worth the extra cost?


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When should a modified binderWhen should a modified binder

be specified?be specified?•• In extreme climatic conditions (very hot orIn extreme climatic conditions (very hot or

very cold)very cold)•• In very heavy traffic conditions, especiallyIn very heavy traffic conditions, especially

when loading is slow or stoppedwhen loading is slow or stopped

•• In problem situations where rutting, shoving,In problem situations where rutting, shoving,instability is occurringinstability is occurring

•• Where improved elastic properties areWhere improved elastic properties areneeded (i.e. resistance of reflective cracking)needed (i.e. resistance of reflective cracking)

•• To provide for thicker binder film thicknessTo provide for thicker binder film thicknessin open graded and gap graded mixesin open graded and gap graded mixes


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•• Black, glueBlack, glue--like, waterproof materiallike, waterproof material

•• A product of the petroleum refining operationA product of the petroleum refining operation

•• Used extensively in the paving, roofing industriesUsed extensively in the paving, roofing industries

•• Is a thermoplastic materialIs a thermoplastic material

•• Must be in liquid form for roadway applicationsMust be in liquid form for roadway applications(heat, dilution in solvent, emulsification)(heat, dilution in solvent, emulsification)

•• Can be used in pavements effectively in the full rangeCan be used in pavements effectively in the full range

of climate and loading conditionsof climate and loading conditions

•• Can be polymer modified to improve properties forCan be polymer modified to improve properties for

better performance when necessarybetter performance when necessary


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Performance Graded BindersPerformance Graded Binders

•• HistoryHistory•• TestingTesting

•• SpecificationSpecification

•• Grade SelectionGrade Selection


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•• Product of Strategic Highway ResearchProduct of Strategic Highway ResearchProgram (SHRP)Program (SHRP)

•• New tests and specificationNew tests and specification

•• Provides a temperature range throughProvides a temperature range throughwhich the asphalt must meet certainwhich the asphalt must meet certainphysical properties to resist rutting andphysical properties to resist rutting and

crackingcracking•• Includes conditioning procedures toIncludes conditioning procedures to

simulate changes in asphalt propertiessimulate changes in asphalt properties

due to aging in the fielddue to aging in the field

HMA BindersHMA Binders--

Performance Graded (PG) SystemPerformance Graded (PG) System


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Pavement Temperature, CPavement Temperature, C

-- 2020 2020 6060 135135

Illustration of PG Binder TestsIllustration of PG Binder Tests

Low Temp.Low Temp.CrackingCracking

FatigueFatigueCrackingCracking

RuttingRutting HandlingHandling

L T t C kiL T t C ki


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Low Temperature CrackingLow Temperature Cracking

Alli C ki


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Alligator CrackingAlligator Cracking

(Fatigue)(Fatigue)


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Rutting in Subgrade or BaseRutting in Subgrade or Base


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Rutting in Asphalt Surface LayerRutting in Asphalt Surface Layer

R tti t R d b tRutting at a Roundabout


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In what layer is rutting occurring?

Rutting at a RoundaboutRutting at a Roundabout


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Superpave Asphalt BinderSuperpave Asphalt Binder

SpecificationSpecification

• Grading System Based on Climate

PerformancePerformance

GradeGradeAverage 7Average 7--dayday

max pavementmax pavement

design tempdesign temp

Min pavementMin pavement


PG 58PG 58 -- 2222


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Performance Graded BinderPerformance Graded Binder

SpecificationsSpecifications

•• Superior to viscosity and penetrationSuperior to viscosity and penetrationgrading systemsgrading systems

•• Have resulted in higher quality bindersHave resulted in higher quality binders

•• Allow appropriate grade of binder forAllow appropriate grade of binder for

specific location based upon:specific location based upon:

– – air and pavement temperatureair and pavement temperature

– – loading conditionsloading conditions

– – traffic speedtraffic speed


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FatigueFatigue

Cracking Cracking Rutting Rutting ConstructionConstruction

[RV][RV][DSR][DSR]

Low Temp Low Temp

Cracking Cracking

[BBR][BBR]

[DTT][DTT]

Pavement AgePavement Age

PAV PAV -- aging aging No aging No aging

RTFO RTFO -- aging aging


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R R ollingolling TThinhin FFilmilm OOvenven

163 C

controlscontrols fanfan

bottle carriagebottle carriageair jetair jet


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asphaltasphalt

sample pansample pansample rack sample rack pressure vesselpressure vessel

airair

pressurepressure

temperaturetemperatureprobeprobe

PPressureressure AAgingging

VVesselessel


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samplesample

chamberchamber

spindlespindle

asphalt sampleasphalt sample

applied torqueapplied torque

from motorfrom motor

Rotational ViscometerRotational Viscometer


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Oscillating PlateOscillating Plate

FixedFixed

Base PlateBase Plate

BinderBinder

SampleSample

DSR Test EquipmentDSR Test Equipment


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FluidFluid

BathBath

Deflection TransducerDeflection Transducer

Load CellLoad Cell

Asphalt BeamAsphalt Beam

Air BearingAir Bearing

LoadingLoading

FrameFrameSupportsSupports

Control andControl andData AcquisitionData Acquisition

Temperature Probeemperature Probe


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DDirectirect TTensionension TTesterester

change in length (change in length ( L)L)

effective gauge length Leffective gauge length Lee

failure strain (failure strain ( f f ) =) =

LL

LoadLoad

LLLLee

LL ++ LLFailureFailure

PPerformanceerformance GGradesrades


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PG 46 PG 52 PG 58 PG 64 PG 70 PG-76 PG 82

(Rotational Viscosity) RV

90 90 100 100 100 (110) 100 (110) 110 (110)

(Flash Point) FP

46 52 58 64 70 76 82

46 52 58 64 70 76 82

(ROLLING THIN FILM OVEN)(ROLLING THIN FILM OVEN) RTFORTFO Mass LossMass Loss 1.00 kPa

< 5000 kPa

> 2.20 kPa

S < 300 MPa m > 0.300

Report Value

> 1.00 %

20 Hours, 2.07 MPa

10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 8 25 22 19 37 34 31 28 25 40 37 34 31

(Dynamic Shear Rheometer) DSR G* sin

( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value

-24 -30 -36 0 -6 12 -18 -24 30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

-2 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

(Dynamic Shear Rheometer) DSR G*/sin

(Dynamic Shear Rheometer) DSR G*/sin

< 3 Pa.s @ 135 oC

> 230 oC

CEC

Which PG grades should I useWhich PG grades should I use


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Which PG grades should I useWhich PG grades should I use

at my facility???at my facility???•• Many factor to considerMany factor to consider – – Suggested grades from Superpave WeatherSuggested grades from Superpave Weather

DatabaseDatabase

– – Amount and type of traffic loadingsAmount and type of traffic loadings

– – Desired reliabilityDesired reliability – – Reclaimed Asphalt Pavement (RAP) usageReclaimed Asphalt Pavement (RAP) usage

– –

Current available gradesCurrent available grades

– – Capabilities of binder suppliersCapabilities of binder suppliers

– – Typical types of distress in pavementsTypical types of distress in pavements

– – Binder costsBinder costs

Developed from AirDeveloped from Air


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pp

TemperaturesTemperatures

•• Superpave Weather DatabaseSuperpave Weather Database – – 6500 stations in U.S. and Canada6500 stations in U.S. and Canada

•• AnnualAnnual airair temperaturestemperatures – – hottest sevenhottest seven--day temp (avg. and std dev)day temp (avg. and std dev)

– – coldest temp (avg. and std dev)coldest temp (avg. and std dev)•• CalculatedCalculated pavementpavement temperaturestemperatures

used in PG selectionused in PG selection

> 20 years> 20 years

S H R P

S H R P AA- - 6 4 8 A6 4 8 A

Eff t f L di R tEffect of Loading Rate on


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Effect of Loading Rate onEffect of Loading Rate on

Binder SelectionBinder Selection

•• DilemmaDilemma – – specified DSR loading rate is 10 rad/secspecified DSR loading rate is 10 rad/sec

– – what aboutwhat about longerlonger loading times ?loading times ?

•• Use binder with more stiffness atUse binder with more stiffness at

higher tempshigher temps

– – slowslow -- -- increase one high temp gradeincrease one high temp grade

– – stationarystationary -- -- increase two high temp gradesincrease two high temp grades

– – no effect on low temp gradeno effect on low temp grade

90 kph90 kph


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Effect of Loading Rate onEffect of Loading Rate on

Binder SelectionBinder Selection

•• Example with heavy loadingExample with heavy loading

– – for toll roadfor toll road

PG 64PG 64--2222

– – for toll boothfor toll booth

PG 70PG 70--2222

– – for weigh stationsfor weigh stations

PG 76PG 76--2222

90 kph90 kph

SlowSlow

StoppingStopping

Eff t f T ffi A tEff t f T ffi A t


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Effect of Traffic AmountEffect of Traffic Amount

on Binder Selectionon Binder Selection

•• 1010 -- 30 x 1030 x 1066 ESALESAL

– – Consider increasingConsider increasing ---- one high tempone high tempgradegrade

•• 30 x 1030 x 1066 + ESAL+ ESAL – – Recommend increasingRecommend increasing ---- two high temptwo high temp

gradesgrades

80 kN ESALs80 kN ESALs

>> EEquivalentquivalent SSingleingle AAxlexle LLoadsoads


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Superpave Asphalt BinderSuperpave Asphalt Binder

SpecificationSpecification

• Grading System Based on Climate

PG 58PG 58 -- 2222

PerformancePerformanceGradeGrade

Average 7Average 7--daydaymax pavementmax pavement


Min pavementMin pavementdesign tempdesign temp

Which PG asphalt shouldWhich PG asphalt should


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perform best in resistingperform best in resistingthermal cracking?thermal cracking?

•• PG 64PG 64--2222

•• PG 76PG 76--2222•• PG 64PG 64--2828

•• PG 58PG 58--3434



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perform best in resistingperform best in resistingthermal cracking?thermal cracking?

•• PG 64PG 64--2222

•• PG 76PG 76--2222•• PG 64PG 64--2828

•• PG 58PG 58--3434

i f f i G


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Which of the following PGWhich of the following PG

binders should perform best inbinders should perform best inresisting rutting?resisting rutting?

•• PG 82PG 82--2222

•• PG 76PG 76--2828

•• PG 70PG 70--2828

•• PG 76PG 76--2222

Whi h f h f ll i PG


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Which of the following PGWhich of the following PG

binders should perform best inbinders should perform best inresisting rutting?resisting rutting?

•• PG 82PG 82--2222

•• PG 76PG 76--2828

•• PG 70PG 70--2828

•• PG 76PG 76--2222


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SuperpaveSuperpave Binder Binder ImplementationImplementation

1999 Lead State Survey1999 Lead State Survey

2003

2004

Undetermined


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PG Binders in South CarolinaPG Binders in South Carolina

•• Adopted in 2000 for all work Adopted in 2000 for all work

•• Two grades selected:Two grades selected:

– – PG 64PG 64--2222

•• Low volume secondary, primary andLow volume secondary, primary and

interstate pavementsinterstate pavements

– – PG 76PG 76--2222•• Heavy loaded interstate andHeavy loaded interstate and specealtyspecealty

locations (intersections)locations (intersections)


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Performance Graded BinderPerformance Graded Binder

Testing, Specification andTesting, Specification and

Grade SelectionGrade Selection

Questions?Questions?

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