Prepared for the WRI Symposium:

Pavement Performance PredictionGayle & Helen King

Foundation for Pavement Preservation / FHWA

Spray Applied Polymer Surface Seals

An Effective Preservation Program

Cost effectively extends pavement life

Minimizes extensive rehabilitation & resulting traffic congestion

Provides smoother, high friction surfaces

Improves ride quality & safety

Pavement Preservation Benefits of Preventive Maintenance

Pavement Structural Condition w/ time

Excellent

Good

Fair

Poor

Very Poor

Failed

40% drop in quality

75% of life

40% drop in quality

12% of life

$1.00 for PM here

Pave

men

t Str

uctu

ral C

ondi

tion

5 10 15 20

Years

Will save $3.00to $10.00 here

NOWOr here

How Do We Do It?

Asphalt Surface ApplicationsFog Seal

SealRestore AC

Dust Palliative Prime CoatTack Coat

DOT Survey

Why Fog Seal?

0 5 10 15 20 25

Reduce Oxidation

Pitting/Raveling

Reduce Shrinkdage

Close or Seal Cracks

Decrease Permeability

Construction Defects

Reduce Shrinkage

DOT SurveySurface Types That Are Fog Sealed

0 5 10 15

Dense Graded

OGFC

Chip Seals

Slurry Seal

Micro Surfacing

Improve Aggregate Retention For Chip Seals?

No Fog

Fog Seal

Arizona Highway 87

DOT SurveyPavement Age When Fog Seals Applied

0 2 4 6 8

At Construction

0 - 2 Years

3 - 5 Years

6 - 10 Years

> 10 Years

DOT SurveyAre Fog Seals Cost Effective?

0 5 10 15 20 25

Yes

No

What can a fog seal do?

Pavement Preservation: Early Intervention

CONFIDENTIAL

•Deleterious Effects of Oxygen

•Moisture Intrusion•Aggregate Loss

Fog Seals can reduce:

CONFIDENTIAL

Can Fog Seals Mitigate

Cracking?

CONFIDENTIAL

Issue of the Day!

To prevent age-induced cracking, first understand:

Asphalt Durability

Claine Petersen: A durable asphalt: 1. possesses physical properties necessary

to produce desired initial product performance &

2. is resistant to change in physical properties during long-term, in-use environmental aging

Petersen, J.C., “Chemical Composition of Asphalt as Related to Asphalt Durability-State of-the-Art”, TRR. 999, 1984

Asphalt OxidationVallerga: Age-Embrittlement

Raveling Block Cracking

Asphalt Oxidation ChemistryThe Products

Petersen, Mill, Greene

Oxidation ProductsCarbonyls form in three steps:

KetonesCarboxylic Acids, AldehydesAcid anhydrides

Sulfoxides; Disulfoxides

For evolving rheology, carbonyls matter, sulfoxides don’t!

What about further aromatization?

Asphalt Oxidation ChemistryThe Kinetics

Petersen, Van Gooswilligen, Mill, Glover

Oxidation Kinetics Temperature dependence

G* & Carbonyl follow Arrhenius (exp (1/T)m-value – ??? (falls off a cliff)

Pressure dependence - exponentialDefined rate determining step

Bitumen, O2, catalyst

Classic phenols inhibitors don’t workIdentified reaction inhibitors (CN-)

Auto-oxidation doesn’t fit kinetics!

Asphalt Oxidation ChemistryThe Mechanisms

Petersen/Branthaver/Harnsberger, Beaver/King

Carbonyl Oxidation MechanismsDual Mechanisms – 2 reaction rates

one fast, but slows or stops with timeone slow, but continues indefinitely

N-ETIO – Electron Transfer MechanismOxycyclics explain rate determining step, unusual carbonyl products (anhydrides), influence of catalystsInitiated by triplet-to-singlet electron spin flip

Asphalt OxidationPhysical Changes

Conventional Wisdom:

Kandhal tied block cracking severity to ductility at 60ºF (15ºC)

Loss of surface fines as ductility → 10cm

Surface cracking evident when ductility falls to 5cm

“Low-Temperature Ductility in Relation to Pavement Performance”, ASTM STP 628, 1977

Asphalt OxidationPredicting Pavement Failures

Global Aging Effects ModelAs developed for MEDGUses asphalt age-hardening approach by modeling high temp ή or G*

Mirza, M.W. and Witczak, M.W., “Development of a Global Aging System for Short- and Long-Term Aging of Asphalt

Cements”, AAPT, 1995

Asphalt DurabilityPredicting Block Cracking

Challenge question:Asphalt oxidation accelerates at high

pavement temperatures, but does block cracking occur at lower temperatures?

If yes, why not use low temperature physical properties to predict block cracking?

Critique of Global Aging System:Christensen, D.W. and Bonaquist, R.F., “Volumetric

Requirements for SuperPave Mix Design”, NCHRP Report #567, TRB, 2006

WRI Aging Study - HarnsbergerARIZONA FIELD AGING

Hypothesis: Asphalts from

different crude oil sources will exhibit different field performance

ARIZONA VALIDATION SITE

Constructed Nov. 2001Shoulder cored Nov. 2005

2 – 63 mm lifts, 19-mm NMS dense graded aggregate, 4.7% AC)

Effect Of Pavement Depth On Aged Asphalt Properties

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09

1E-06 1E-04 1E-02 1E+00 1E+02 1E+04 1E+06 1E+08 1E+10

Reduced Angular Frequency (rad/s)

Com

plex

Mod

ulus

(Pa)

Top Slice

2nd S lice

3rd Slice

Bottom Slice

AZ1-1, 4th Year, Shoulder

After Oxidation:

Top slice > 2nd slice > 3rd slice > Bottom slice

0

10

20

30

40

50

60

70

80

90

1E-06 1E-04 1E-02 1E+00 1E+02 1E+04 1E+06 1E+08 1E+10

Reduced Angular Frequency (rad/s)

Phas

e A

ngle

(deg

)

AZ1-1, 4th Year, Shoulder

Top Slice

2nd Slice

3rd Slice

Bottom Slice

EFFECT OF PAVEMENT DEPTH ON AGED ASPHALT PROPERTIES

After Oxidation:Top slice > 2nd slice > 3rd slice > Bottom slice

SuperPave Grading of Airblown ACTemperature Where SHRP Criteria are Met, °C

-40-34-28-22-16-10

-428

142026323844505662687480869298

104110116

R&B 104 R&B 125 R&B 154 R&B 172 R&B 204

G*/sin d=1.0kPa

RTFO G*/sind=2.2 kPa

PAV G* sind=5000 kPa

PAV BBRS=300 MPa

PAV BBRm=0.300

PG 52-34

PG 70-28

PG 88-4 PG 94-? PG 118-?

Comparison of m-Value & S Gradesfor AAS-1 & Exxon AC-20 at Various Aging Times

Glover, et.al. FHWA/TX-05/1872-2

Fog Seal

Surface Modulus

Dynamic Creep (DSR Torsion)

Rheology Testing of Field Samples

Rheology of Extracted CoresMN 251

0

2000

4000

6000

8000

10000

12000

Reclamite PASS CRF CSS-1h GSB-B Control

G*,

PA, 1

0 ra

dian

s/se

c, 6

4 C Top Slice

Slice 2

Tested by Western Research InstituteDynamic Shear Rheometry on Liquid Samples Extracted from Field Cores (DSR)

Rheology of Core SlicesMN 251

0

50

100

150

200

250

300

350

400

450

Reclamite PASS CRF CSS-1h GSB-B Control

Tim

e to

5%

Str

ain

@ 5

8 C

(sec

) Top SliceSlice 2

Tested by Mathy Technology & Engineering Services, Inc.Dynamic Creep Test on Rectangular Specimens from Field Cores (DSR)

MN TH 251 Project - Dense-Graded, Impermeable SurfaceTests on binder from extracted cores by WRI, Tests on mix slices from cores by MTE

Fog Seal

Lab PermeabilityPhoto

G*,

Pa, 1

0 ra

dian

s/se

c, 6

4C

0

5000

1000015000

20000

25000

30000

Con

trol

CSS

-1h

Rec

lam

ite

ERA-

25

ERA-

1

Pass

QB

Con

trol

Con

trol 2

CSS

-1h

Rec

lam

ite

ERA-

25

ERA-

1

Pass

QB

Test on Extracted Binder From Field Cores(G*)

Test on Mix Slices from Lab Treated Cores (Timeto 5% Strain)

0200400600800100012001400160018002000

AZ 87 Project

Tim

e to

5%

Str

ain,

58ºC

, 68k

Pa s

tres

s0

2000

4000

6000

8000

10000

12000

Rec

lam

ite

Pass

QB

CR

F

CSS

-1h

GSB

-B

Con

trol

Rec

lam

ite

Pass

QB

CR

F

CSS

-1h

GSB

-B

Con

trol

Test on Extracted Binder (G*) Test on Mix Slice (Time to 5% Strain)

050100150200250300350400450

Top 0.3" Slice2nd Layer Slice

MN 251 Project

Binder tests by WRI, Mix tests by MTE

Core Slice Binder & Mix Rheology

Fog SealLow Temperature Mix Stiffness & m-value

Bending Beam Rheometer (BBR)Rectangular beams - standard BBR geometry

$200 tile saw cuts surface mix specimens

Condition & test in BBR at -18 to -6ºC

Static Bending Test on RectangularSpecimens Cut from Field Cores (BBR)

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Con

trol

ERA

'01

Rec

lam

ite'0

1R

ecla

mite

'01

& '0

6R

ecla

mite

'06

Pass

QB

'01

CS

S '0

1

Con

trol

Rec

lam

ite'0

2R

ecla

mite

'04

CR

S-2

Pd'0

6

LD-7

'06

Pass

QB

'02

CR

F '0

2

Chi

p S

eal

CR

S-2

Pd

AZ 87 (dense-graded) MN TH 251

m-v

alue

at -

12 C

0

1000

20003000

4000

5000

6000

70008000

9000

10000

Stiff

ness

at -

12C

(MPa

)

m-valueS [MPa]

Static Bending Test on Rectangular Specimens from Field Cores Tested by Bending Beam Rheometer Cores taken in Sept and Oct 2006 - year is date of seal - Samples prepared and tested at UMinn

Hypothesis for:Cracking at low temperatures

1. Thermal Cracking1. Driven by Thermal Shrinkage Stresses on Cooling2. Function of Binder Stiffness

2. Block Cracking1. Driven by Curling Stresses from Temp Gradients2. Function of Binder Relaxation 3. Crack-Initiation Temp increases with oxidation:

Decreasing BBR ‘m-value’, but constant “S”Decreasing DTT failure strainDecreasing R-valueLower phase angle at a given modulusDecreasing Fracture energy

Research NeedsEnvironmental effects models

Predict rate of oxidative agingTemperature dependence of ??: PAV @ 3 tempsCompiled pavement temperature data from LTPPBind rutting damage model

Predict initiation of block cracking?Tools which can be used to time pavement preservation applicationsPerformance specifications

Material purchase specifications for recycling/rejuvenation binders

Fog Seals:Study Objectives

Evaluate Effectiveness of Fog SealsSealersRejuvenators

Optimize Timing Of ApplicationsEvaluate potential technologies for determining “triggers” or intervention points

Develop a Fog Seal WebsiteNCPP –www.pavementpreservation.org/fogseals/

National and Local Technology Transfer

Test Section Locations

Winlsow, AZ (3 Surfaces, 18 Test Sections)Resealed Fall ‘06

Salton Sea, CA (1 Surface, 5 TS)Marysville, CA (1 Surface, 6TS)Maple Island, MN (1 Surface, 8 TS)

Resealed Fall ’06

Rochester, MN (1 Surface, 8 TS)New trial with WRI study: Fall ’06Newly constructed pavementSanding study; evaluate early friction

Typical Pavement Trial

1 2 3 4 5 6 7 8

Reclamite Control CSS-1h GSB (B) CRF Pass Oil MegaTec Chipseal

Test Section Layout

Year Zero – Initial Application Transition Transition Transition

Year Two – Second Application

Year Four – Third Application

Outlined areas = application of material that year

Shaded areas = previously treated sections Material 1 Material 2 Material 3 Additionally, 500-ft section left untreated as control

100 ft 400ft

Evaluation Approach

Chemical & Rheological TestingFriction & Texture MeasurementNon-Destructive Testing for Assessing When to Apply TreatmentsDistress EvaluationPermeability/Infiltration Testing

Study Participants –Acknowledgements

Federal Highway Administration (FHWA) - SorensonFoundation for Pavement Preservation (FP2) - EllerArizona Department of Transportation (ADOT) - ScofieldState DOTs: MN, CA, AZ, MIGHK, Inc. – Gayle & Helen King

Research ParticipantsAcknowledgements

WRI: Binder Extraction/TestingNCSC: Friction/PermeabilityMTE: DRS TorsionUMinn: BBR on thin mixUTEP: PSPAAkzo Nobel: Emulsion Testing

Industry ParticipantsAcknowledgements

Tricor RefiningReclamite; ERA-1; ERA-25

Western EmulsionsPass QB

Blacklidge EmulsionsLD-7

Asphalt SupplyGSB-Modified

Koch MaterialsCSS

Flint Hills RefiningCRS-2Pd

Paramount RefiningCSS

Where to Use Fog Seals?

Pavement Surface TypeDense HMA

Superpave CoarseSuperpave FineSMA – “Gap-Graded Superpave”

Open-Graded Friction CourseChip Seal

New or old

Asphalt-Rubber

Fog Seal for Dense HMA

Rejuvenator Emulsions:Aromatic/Naphthenic rejuvenator oilsAC/rejuvenator oilsPMAC/rejuvenator oils

Sealer Emulsions:Dilute SS/CSSDilute RS/CRS (soap dilution)Dilute QS/CQSSpecialty emulsions

Fog Seal for OGFC

Objective:Recoat & restore aged asphalt to reduce ravelingEmulsion grades:

SS/CSSPMA chip seal emulsionsMicro-surfacing emulsionsPMA/rejuvenator oil blends

Fog Seal over Chip Seal

Objectives: Suppress dust Tie down loose aggregatePavement color (black like hot mix!)

Emulsion Grades:SS/CSSCRS/RS/HFRSPolymer-modified emulsions

Minnesota - CRS-2P (d)

Fog SealWhere to Use?

Pavement LocationTravel LanesShoulders

Color delineation for safetyReduce permeability

Airfields

Fog SealWhen to Use?

Pavement AgeSeal newer pavementsRejuvenate age-embrittled pavements

Pavement ConditionLow severity of cracking (or preferably none)RavelingAC/HMA rheology – critical “m” value

Pavement PermeabilityMix design (coarse, fine, open, SMA/gap-grade)Construction density Densification under traffic

Fog SealConstruction

Distributor Emulsion dilution/application rate?

Nozzle: size, angle, plugged?

Bar height? Bar Pressure? Speed?

Calibration

Use of fractured sandApplication rate?

Time to brooming?

Time to trafficSkid requirementsTest Strips

Fog SealProducts

Rejuvenator emulsionsOils: ETR-1; ARA-1; Reclamite®

AC/Oil: Cyclogen®; ERA®

PMAC/Oil: Pass QB®

Sealer emulsionsSS/CSS; CSS-1hP; Ralumac®

RS/CRS; CRS-2Pd, HFE-100S

QS/CQS: LD-7®

Gilsonite-based: GSB® -Modified

Fog SealField Test Methods

Pavement PermeabilityEmulsion InfiltrationSurface Modulus or “m-value”Friction

Fog SealPavement Permeability

NCAT Device

Fog SealEmulsion Infiltration

Ring Test

Fog SealSurface Modulus

Portable Seismic Pavement Analyzer

Fog SealFriction & Texture Testing

Dynamic Friction Test

Fog SealPavement Friction

Circular Texture Meter

Friction of Newly Treated MN TR112 with & without Sand

From Dynamic Friction Tester/ Circular Texture Meter immediately after application and curing.Tested by North Central Superpave Center

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Control CRS 2P Pass QB LD7 ReclamiteTreatment

IFI

(Inte

rnat

iona

l Fric

tion

Inde

x)

UnsandedSanded

Change in Friction With Time After Application

Percent Change From Pre-Treatment Friction Levels Tested at 80 kph (Marysville)

-35

-30

-25

-20

-15

-10

-5

0

5

0 50 100 150 200 250 300Time Since Treatment Applied (Days)

Chan

ge

In

Fric

tion L

evel

s (%

)

ControlReclamitePass QBCQS-1hCSS-1hTopein C

Comparison of IFI and Friction Trailer (E-264) Resultson MN County Road 112

0

10

20

30

40

50

60

Control CRS-2Pd Pass QB LD-7 Reclamite

FN (I

RI x

100

)

IFI - Sanded SectionsIFIRun 1 Ribbed TireRun 2 Ribbed TireRun 3 Smooth Tire

IRI tested same day by South Central Superpave CenterE-264 by Mn/DOT several days later

r2 = 0.711 for Ribbed Tirer2 = 0.757 for Smooth Tire

Comparison of Friction TestsMN 251 – 2006 Trial

IFI as measured by DFT/CTM – Tested by North Central Superpave CenterFull-Scale Tire Testing (ASTM E-274) on MN 251 – Tested by Mn/DOT

0

10

20

30

40

50

60

70

Control Control CRS-2P(d)

LD-7 LD-7Sanded

Pass QB Reclamite ReclamiteSanded

ChipSeal/CRS-

2PdTest Section

Fric

tion

Num

ber

(Inte

rnat

iona

l Fric

tion

Inde

x (IF

I) is

X10

0

IFI (x 100)E-274 w Smooth TireE-274 w Ribbed Tire

r2 = 0.9019 for Smooth Tirer2 = 0.9125 for Ribbed Tire

Fog Seal

Lab Test Methods

Extracted Binder Rheology - DSRDSR Torsion (time to 5% strain) –Mix SurfaceBBR S & m-value – Mix SurfaceLab Permeability of Pavement CoresEmulsion Properties

Viscosity, Surface Tension, Particle Size

Emulsion Residue

Fog Seal

Binder PropertiesBinder Extraction

Toluene/95% EthanolBinder Rheology

DSR; G*, phase angle, MSCRBBR: S, “m-value”, physical hardening

Binder ChemistryInfrared Spectroscopy (IR) - carbonyl

Nuclear Magnetic Resonance (NMR) - branching

Differential Scanning Calorimetry (DSC)– wax Elemental Analysis – chemical fingerprintHPLC - EH&S issuesKing’s opinion: forget Rostler, Corbett, asphaltenes

Fog Seal

Emulsion Properties

Surface Tension

Particle Size

Disk Centrifuge

Saybolt-Furol Viscosity

Pavement AgingSealing Pavements

The principle of pavement seals:

Can we reduce rate of carbonyl formation by limiting the molecular oxygen in the pavement?

Answer:

Chip seals – yesFog seals – marginal improvement

How Do We Develop Specifications for Fog Seal Emulsions

Define performanceDifferentiate needs for:

Surface Type: HMA, OGFC, Chip SealTraffic: travel lane vs shoulder

Develop performance-related test methods

Create generic performance specs with defined limitsEmulsion purchase criteria

Emulsion propertiesResidue properties

Establish residue recovery method

Construction criteria

Fog Seal Specifications

CALTRANS experienceCurrent

5 essentially proprietary product-specific specs

In-Committee

5 generic prescriptive specs for product families

New Research

Performance specs for fog seal

MARTEC – Dr. Hicks

Thank You. Questions?

MN 251 in Light RainAfter 4 yrs

Rheology Testing of Field Samples

Rheology of Extracted CoresMN 251

0

2000

4000

6000

8000

10000

12000

Reclamite PASS CRF CSS-1h GSB-B Control

G*,

PA, 1

0 ra

dian

s/se

c, 6

4 C Top Slice

Slice 2

Tested by Western Research InstituteDynamic Shear Rheometry on Liquid Samples Extracted from Field Cores (DSR)

Rheology of Core SlicesMN 251

0

50

100

150

200

250

300

350

400

450

Reclamite PASS CRF CSS-1h GSB-B Control

Tim

e to

5%

Str

ain

@ 5

8 C

(sec

) Top SliceSlice 2

Tested by Mathy Technology & Engineering Services, Inc.Dynamic Creep Test on Rectangular Specimens from Field Cores (DSR)

MN TH 251 Project - Dense-Graded, Impermeable SurfaceTests on binder from extracted cores by WRI, Tests on mix slices from cores by MTE

Dynamic Shear Rheometryon Extracted Binder from Lab Treated Field Cores

Tested by Western Research Institute

0

5000

10000

15000

20000

25000

30000R

ecla

mite

PA

SS

ER

A-1

ERA-

25

CS

S-1

h

Con

trol

Rec

lam

ite

PA

SS

CR

F

CS

S-1

h

GS

B-B

Con

trol

AZ 87 - Dense-Graded MN 251 - Dense-Graded

G*,

Pa, 1

0 ra

dian

s/se

c, 6

4C

Top 0.3" Slice2nd Layer Slice