Polymer Modified Polymer Modified A h lA h lAsphaltAsphalt

. . . Longer Lasting Roads. . . Longer Lasting Roads

WhyWhyWhy Why Polymer?Polymer?Polymer?Polymer?

Improve pavement performance Improve pavement performance p p pp p pLower life cycle costsLower life cycle costs

For perpetual pavementsFor perpetual pavementsFor perpetual pavementsFor perpetual pavements

Longer Lasting Roads. . .

Definition of a PolymerDefinition of a PolymerDefinition of a PolymerDefinition of a Polymer

The term “polymer” refers to a largeThe term “polymer” refers to a largeThe term polymer refers to a large The term polymer refers to a large molecule formed by chemically reacting molecule formed by chemically reacting

(“ l ”) ll l l(“ l ”) ll l lmany (“poly”) smaller molecules many (“poly”) smaller molecules (monomers) to one another in long chains (monomers) to one another in long chains or clusters.or clusters.Physical properties of a specific polymerPhysical properties of a specific polymerPhysical properties of a specific polymer Physical properties of a specific polymer are determined by the sequence and are determined by the sequence and chemical structure of the monomers fromchemical structure of the monomers fromchemical structure of the monomers from chemical structure of the monomers from which it is made.which it is made.

Types of PolymerTypes of PolymerTypes of PolymerTypes of Polymer

ELASTOMERSELASTOMERSELASTOMERSELASTOMERSAble to stretch under load then recover to Able to stretch under load then recover to original shape when the load is removed.original shape when the load is removed.Provide benefit when deformed.Provide benefit when deformed.Used in asphalt binders in HMA mixtures to Used in asphalt binders in HMA mixtures to resist:resist:

Permanent deformation andPermanent deformation andCohesive failureCohesive failureCohesive failure.Cohesive failure.

ELASTOMERELASTOMERSB/SBS block coSB/SBS block co--polymerpolymerSBRSBRSBRSBR

Reduces temperature susceptibilityReduces temperature susceptibilityIncreases strain recoveryIncreases strain recoveryIncreases strain recoveryIncreases strain recoveryTensile strength at high strainsTensile strength at high strainsI h iI h iIncreases cohesionIncreases cohesionIncreases adhesionIncreases adhesion

Why Modify?Why Modify?Why Modify?Why Modify?

Increase serviceable temperature rangeIncrease serviceable temperature rangeIncrease serviceable temperature rangeIncrease serviceable temperature rangeStiff at high temperatureStiff at high temperatureFlexible at low temperatureFlexible at low temperaturepp

Improve durability at all temperaturesImprove durability at all temperaturesReduce moisture damage Reduce moisture damage Address construction issues:Address construction issues:

Reduce draindown for SMA/OGFCReduce draindown for SMA/OGFCM f i i bi dM f i i bi dMore forgiving binder:More forgiving binder:

reduce secondary damage at cracks/jointsreduce secondary damage at cracks/jointsless raveling/stripping in segregated areasless raveling/stripping in segregated areasless raveling/stripping in segregated areasless raveling/stripping in segregated areas

Polymer Modified AsphaltsPolymer Modified AsphaltsPolymer Modified AsphaltsPolymer Modified Asphalts

Polymer network structurePolymer network structurePolymer network structurePolymer network structure

determines PMAC’s physical propertiesdetermines PMAC’s physical properties

The network structure depends on:The network structure depends on:The network structure depends on: The network structure depends on:

chemistry of both asphalt and polymer chemistry of both asphalt and polymer

their compatibilitytheir compatibilitytheir compatibilitytheir compatibilityPERFORMANCE OF A PMA DEPENDS ON THE PERFORMANCE OF A PMA DEPENDS ON THE

COMPATIBILITY BETWEEN ASPHALT AND COMPATIBILITY BETWEEN ASPHALT AND POLYMERPOLYMER

Examples of asphaltsExamples of asphaltsExamples of asphalts Examples of asphalts (all AC(all AC--20s with 6% of the same SBS polymer)20s with 6% of the same SBS polymer)

Asphalt A Asphalt C Asphalt DAsphalt BReflective florescence photomicrographsReflective florescence photomicrographs.White is polymer, black is asphaltIdeal microstructure: finely networked polymer in asphalt

Performance TestsPerformance Tests

Binder testingBinder testing

Superpave PG binder gradingSuperpave PG binder gradingSuperpave PG binder gradingSuperpave PG binder gradingPolymer is less temperature susceptiblePolymer is less temperature susceptible

-1652 58 64 70 76 82 88

SHRP High Temperature, °C

Increased

-28

-22

P Lo

w

p, °

C

Increased resistance to thermal

ki

40

-34

-28

SHR

PTe

mp cracking

-40

Unmodified AC PMAC

Increased resistance to rutting

PG+PG+ SPECIFICATIONSPECIFICATIONPG+PG+ SPECIFICATIONSPECIFICATION

Toughness and TenacityToughness and TenacityToughness and Tenacity Toughness and Tenacity Ductility at 4Ductility at 4°°CCDuctility at 4Ductility at 4 CCElastic RecoveryElastic Recovery

Toughness & TenacityToughness & TenacityToughness & TenacityToughness & Tenacity

Elastic Recovery &Elastic Recovery &Elastic Recovery & Elastic Recovery & Force DuctilityForce Ductility

Elastic polymer recoversrecovers

AC doesn’t

Force Ductility Force Ductility

Unmodified AC

PMAC ( b AC)

Stre

ss

PMAC (same base AC)

S

Strength at elongationgiven by

0 10 20 30 40 50 60 70 80Elongation, cm

the polymer

g ,

P f nP f nPerformance Performance f M difi d Mif M difi d Miof Modified Mixof Modified Mix

R t R i tR t R i tRut ResistanceRut ResistanceSST Shear Creep Test, 40SST Shear Creep Test, 40°°CC

0 2

0.25

% PG 64-22 (unmod)PG 82 22 PMAR

uttin

g

0.15

0.2

Stra

in, PG 82-22 PMA

Response totanc

e to

R

0.05

0.1

Shea

r Response to Applied Load of 35 kPa for 10 seconds

ng R

esis

t

00 10 20

Time, Seconds Dec

reas

in,

Durability Durability -- Fatigue ResistanceFatigue ResistanceWithstands many loading cyclesWithstands many loading cyclesHas greater strain tolerance Has greater strain tolerance

Flexural Beam Fatigue Testing* @ 20°C

5,950PG 76-28 HMA(PMA)

1,950PG 64-22 HMA

0 1000 2000 3000 4000 5000 6000

Cycles to Failure

*AASHTO TP-8

Cycles to Failure

Rut & Moisture ResistanceRut & Moisture ResistanceRut & Moisture ResistanceRut & Moisture ResistanceSame PG 64Same PG 64--22 unmodified & modified22 unmodified & modified

Hamburg WheeltrackingHamburg Wheeltracking

4

-2

0

m

-8

-6

-4

atio

n, m

m

-14

-12

-10

Def

orm

a

PMA 64-22

-18

-16

0 5000 10000 15000 20000N b f C l

Unmodified PG 64-22

Number of Cycles

Resistance to Thermal CrackingResistance to Thermal Cracking-- Indirect Tensile Test (IDT)Indirect Tensile Test (IDT)Indirect Tensile Test (IDT)Indirect Tensile Test (IDT)

1000PMA (~PG 70 28)PG 64-22

600

800Tensile Strength

PMA (~PG 70-28)

400

600g

and Pavement Thermal

200Thermal

Stress (psi)

0-40 -30 -20 -10 0

T t (°C)Temperature (°C)Cracking temperatures

Wh M dif ?Wh M dif ?Why Modify?Why Modify?Field PerformanceField PerformanceField PerformanceField Performance

PMACPMAC •20 years proven performance•Formulated locally

Life Cycle Cost Analysis:Life Cycle Cost Analysis:y yy yPolymer HMA Saves average of $3844 Canadian per LanePolymer HMA Saves average of $3844 Canadian per Lane--

KM on 4 ProjectsKM on 4 Projects

$40$45$50

Cos

ts-k

m

PMAConventionalSavings $/lane-km

$25$30$35$40

Wor

th o

f C1,

000/

lane

- Savings $/lane km

$3 516$7,564

$2 685 $1 612$10$15$20$25

al P

rese

nt

anad

ian

$1

$3,516$2,685 $1,612

$0$5

Highway 401 Coldwater Road Larch Street Durham RegionCSHRP Test Site

Tota Ca

Carrick, Fraser, Hein & Emery, CTAA, 1996

Comparative Field Trials &Comparative Field Trials &Comparative Field Trials &Comparative Field Trials &Life Cycle Cost ComparisonsLife Cycle Cost ComparisonsTexas: Jones Kennedy & TorshiziTexas: Jones Kennedy & Torshizi TRBTRB 19931993Texas: Jones, Kennedy & Torshizi, Texas: Jones, Kennedy & Torshizi, TRB,TRB, 19931993Michigan: Hawley & Baldi, MDOT, 1996Michigan: Hawley & Baldi, MDOT, 1996California: Reese & GoodrichCalifornia: Reese & Goodrich AAPTAAPT 19931993California: Reese & Goodrich, California: Reese & Goodrich, AAPTAAPT, 1993, 1993Maryland: Maryland: Roads & BridgesRoads & Bridges, Fall, 1996, Fall, 1996Kentucky: Blankenship et alKentucky: Blankenship et al AAPTAAPT 19981998Kentucky: Blankenship, et. al., Kentucky: Blankenship, et. al., AAPTAAPT, 1998, 1998Canada: Carrick & Fraser, Canada: Carrick & Fraser, CTAACTAA, 1996, 1996Pennsylvania: Anderson & Maurer,Pennsylvania: Anderson & Maurer, TRBTRB, 1999, 1999Pennsylvania: Anderson & Maurer, Pennsylvania: Anderson & Maurer, TRBTRB, 1999, 1999N.D.O.T.N.D.O.T.Many othersMany othersyy

Binder SelectionBinder Selectiondd

In a Superpave WorldIn a Superpave World

Choosing the rightChoosing the rightChoosing the right Choosing the right liquid AC binderliquid AC binder

LTTPBind softwareLTTPBind softwareLTTPBind softwareLTTPBind softwarePavement TemperaturePavement TemperatureReliability factorReliability factoryyTraffic speed & loadTraffic speed & load

“grade bumping” for prolonged stresses“grade bumping” for prolonged stressesA li iA li iApplicationApplicationPerformance TestingPerformance Testing“SHRP Plus” for desired modification method“SHRP Plus” for desired modification methodSHRP Plus for desired modification methodSHRP Plus for desired modification method

Asphalts that give customers the desired performanceGoal: perpetual pavementsGoal: perpetual pavements

A difi d bi d ff i ?A difi d bi d ff i ?Are modified binders effective?Are modified binders effective?

Enhanced Pavement PerformanceEnhanced Pavement PerformanceLifeLife--cycle costcycle cost -- Ride qualityRide quality -- SafetySafetyLifeLife cycle cost cycle cost Ride quality Ride quality SafetySafety

Physical propertiesPhysical properties of modified mixtureof modified mixtureConstructibilityConstructibilityyy

Stability/Compatibility of AC & modifierStability/Compatibility of AC & modifierQA/QCQA/QCE i t ll f i dlE i t ll f i dlEnvironmentally friendlyEnvironmentally friendly

ManufacturingManufacturing variablesvariablesConsistent productConsistent productConsistent productConsistent product

M n f t r &M n f t r &Houston Hobby AirportManufacture & Manufacture & C t tiC t tiConstructionConstruction

PMAC is easy to usePMAC is easy to usePMAC is easy to usePMAC is easy to use

Preblended prePreblended pre--reacted readyreacted ready--toto--useusePreblended, prePreblended, pre reacted, readyreacted, ready toto useuse

Doesn’t separateDoesn’t separate

N i l i i / i i i dN i l i i / i i i dNo special mixing / agitation requiredNo special mixing / agitation required

No special equipment neededNo special equipment needed

Optimum AC content varies less than 0.1% Optimum AC content varies less than 0.1% from unmodified ACfrom unmodified AC

Mix Temperatures may be slightly higherMix Temperatures may be slightly higher

Check with local rep for product you’reCheck with local rep for product you’reCheck with local rep for product you’re Check with local rep for product you’re usingusing

Normal good practice gives good Normal good practice gives good resultsresults

Preheat screed with screed heaterPreheat screed with screed heaterKeep continuous flow of mix to paver Keep continuous flow of mix to paver

Keeps screed plate hotKeeps screed plate hotCold screed may cause tearing Cold screed may cause tearing Prevents premature cooling of the mixPrevents premature cooling of the mix

Correct temperature give best resultsCorrect temperature give best resultsp gp gClimate, distance of haul, etc. should be Climate, distance of haul, etc. should be consideredconsideredPrevents mix from getting too stickyPrevents mix from getting too sticky

Thank YouThank You

Questions?Questions?