- SPE/BTM-JPP-15-07-2010

Hurdles in Bituminous Binder Characterization

Jean-Pascal Planche, Sylvia Dreessen, Dominique BassetP3 SymposiumLaramie, July 15, 2010

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Outline

Context / Objectives

What are the hurdles?

A few solutions

Lessons learned

Conclusions

Perspectives

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Context

Challenges“How to speak about innovation from old results?”: 100%RAS: Recycled Asphalt Slides !

Asphalt binders are very complexDepending on

Crude Oil OriginTemperatureAging

HMA plantIn situ

Many other factors…

Regardless of the precision of a standard and of applying best practices, difficulties inherent to asphalt binders

Tend to pop up when trying to characterize them

?

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Objective of the presentation

Present some characterization issues that are asphalt material related

Attempt to give explanations and solutionshow to deal with these issues?

Give some perspectives

- SPE/BTM-JPP-15-07-2010

Unmodified asphalt binders

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Maltenes

Structural model of asphalt cements

Resins

Asphaltenes

Colloidal Suspension of asphaltenes in a maltene matrix

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Quite a few characterization issues

Binder generic compositionSECSolvent effect – loss of interactions / associations

Binder structure / morphologyOptical microscopy / FTIR Microscopy / ESEM…At which temperature is seen the sample?Average vs. local compositionArtifacts…

Binder mechanical propertiesClassical testing – penetration Rheology – modulus / phase angle - MSCRTTime and temperature related response / thermal history

Binder thermal propertiesOxidative aging

Loss of volatilesOxidation

Physical hardening…

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Thermal properties

Differential Scanning CalorimetryMeasure of the Glass transition temperature and crystallized fraction

Tg

CF

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Thermal propertiesIssues

Base line determinationThermal history dependency

Initial physical stateCooling or heating rate influence on Tg and on CF

0.50.5°°CC

22

55

1010°°C/minC/min

T=120°C

Conditioning @ T=25°C

Ex: Heating rate effect 6.2 % < CF < 9.5%-33°C < Tg < -28°C

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AAMAAM

Conditioning temperature Conditioning time

AAMAAM

AAGAAG

Thermal properties: Thermal history dependency

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Asphalt morphology

Phase contrast microscopy run @ 25°C, as a function of Crystallized Fraction

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Asphalt morphology

Phase contrast microscopy as a function of temperature upon cooling or heating

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Asphalt morphology

Dark Field microscopyObservations @ ambient temperature by Optical Microscopy - Dark Field Mode

Sample contrast comes from light scattered by the sampleOblique light allows seeing objects on the specimen surface

Crystallized fractions of a neat asphalt

50 µm

Different pattern with FT paraffin waxes added to a neat asphalt

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Links with asphalt mechanic properties?

G*(Pa) = τ/γ

T

rh

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Temperature, °C-50 2000 50 150100

Viscosity

T. Fraass

Thermal Susceptibility of Asphalt cements

Penetration

NF-EN 1426

Rig

idity

/ V

isco

sity

R&B softening point

NF-EN 1427

blown

waxy

800 pen

13000 Po

Delta TDelta T

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Thermal Susceptibility of Asphalt cements

Crystallized fraction (w %)

Del

ta T

°C

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Asphalt Rheology

Unaged asphalt

0

30

60

90

1E+01 1E+03 1E+05 1E+07 1E+09G* (Pa)

Asphalt Bc

T(°C) increase

Viscous

Elastic

Black space – Phase angle as a function of the stiffness modulus from DSR measurement

No shift whatsoever : a single curve… but not always!

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Asphalt Rheology

Black space diagram – effect of asphalt compositionAsphaltene and crystallized fractions

Increasing Crystallized fraction Increasing Asphaltenes

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Asphalt RheologyS

tiffn

ess

(MP

a)

0

200

400

600

800

1000

G H I J K L M N O P Q R

S 1h at -18°C S 24h at -18°C

1

1,5

2

-10 -5 0 5 10

Tconditioning - Tg (°C)

PHF

C45 D45 E60

Effect of Tg on physical hardeningInfluence of the conditioning on

the low temperature stiffness

Physical hardening effect on BBR ranking

BBR

δ(t)

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Physical Hardening factor and CF

11,5

22,5

0 2 4 6 8

Crystallized Fraction (%)

PH

F

Physical Hardening

Influence of the crystallized fraction content

T conditioning = T conditioning = --1515°°CC

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Polymer modified binders

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0

20

40

60

80

100

120

0 2 4 6 8 10 12 14 16 18

SBS content (%)

R&

B (°

C)

Phase Phase InversionInversion

Influence of SBS content on R&B & microstructureInfluence of SBS content on R&B & microstructure

ELASTOMER MODIFIED BINDERELASTOMER MODIFIED BINDER

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•• Phase Separation when SBS above 5Phase Separation when SBS above 5--7%7%

•• Stability at high SBS content around 16%Stability at high SBS content around 16%

••R&B difference not always reflecting instabilityR&B difference not always reflecting instability

ELASTOMER MODIFIED BINDER Storage stability (lab)

% SBS% SBS

SBS m binderSBS m binder

1 3 6 9 12 16

Del

ta P

en (0

.1 m

m)

NeatStored - topStored - bottom

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PmB storage stability following Stokes’ law

•• Emulsion Stability run by:Emulsion Stability run by:• Gravity (density of particles)• Viscosity = Force opposed to g

•• Particles SpeedParticles Speed•• dx/dtdx/dt = 2r²(= 2r²(ρρ22 --ρρ11 )g/9)g/9ηη

r = particles radiusρ1 = density of the external fluidρ2 = density of dropletsη

= viscosity of the media

Stokes’ law => Stokes’ law => creaming when creaming when ρρ22 < < ρρ1 1

PmB = Emulsion where droplets = swollen polymer nodulesPmB = Emulsion where droplets = swollen polymer nodules

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Elastomer Modified Binders

Influence Of Thermal History On Properties

Annealing R&B Annealing R&B 58°C58°C

A. Dony et al. BLPC 168, 7-8/90

Quench R&B 85°CQuench R&B 85°C

Annealing R&B 72Annealing R&B 72--82°C82°CQuench R&B 60°CQuench R&B 60°C

Fabrication R&B 88°CFabrication R&B 88°C

5% SBS PmB5% SBS PmB

180°C180°C

120°C120°C

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PLASTOMER MODIFIED BINDERS

δδ

Mouillet et al E&E Congress 2004

0

10

20

30

40

50

60

70

80

90

1,00E+00 1,00E+01 1,00E+02 1,00E+03 1,00E+04 1,00E+05 1,00E+06 1,00E+07 1,00E+08 1,00E+09

Complex Modulus (Pa)

Phas

e A

ngle

(°)

Complex ModulusComplex Modulus

Upon heating

Upon cooling

Thermal History dependency

Due to EVA cristallinity

Effect on binder properties

What about mix properties?

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PLASTOMER MODIFIED BINDERS Influence of Thermal History on Cristallinity - Melting

LargeaudLargeaud et alet al

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PLASTOMER MODIFIED BINDERS

Influence of thermal history on cristallinity - Crystallization

Largeaud et al

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Repeated Creep Recovery for Plastomer modified Bitumens

0

0,0005

0,001

0,0015

0,002

0,0025

0,003

0,0035

0 2 4 6 8 10 12Time (s)

Com

plia

nce

(Pa-1

)

76°C

70°C

64°C

Last cycle

Last cycle

Last cycle

First cycle

First cycle

First cycle

M18: B13 + 6% EVA-24

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Fatigue Testing of binders – DSR Time sweep

(after Anderson et al, paper # 01 3298 TRB 2001)

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Steric hardening in fatigue testing

Special Bit.

B15 & M17 B15 & M17 lowlow % CF% CF

SB mB

X linked

EVA mB

BitumensHigherHigher % CF% CF

Does S H remain under shear?

T where |G*|=45 MPa

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Steric hardening - Corrections

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600 µm

450

µm

IR Spectroscopy= Global Analysis

Polybutadiene BandPolybutadiene Band

γ γ CC--H characteristicH characteristic

IR Microscopy= Local Analysis

965 cm965 cm--11

FTIR MICROSCOPY

Mouillet et al, BLPC 2000

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Understand internal evolutions during aging

Identify chemical structures

Visualize different microphases

In situ characterizationNo interaction on internal equilibriumLocal FTIR spectroscopic technique

IR mapping to “quantify” polymer dispersion

0.17

1.30

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

Abs

orba

nce

700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 Wavenumbers (cm-1)

450µ

m

600µm

INFRARED MICROSCOPY

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FTIR MICROSCOPY of PmB’s

SBS MA

600µm

450µ

m

EVA MA

600µm

450µ

m

νC-O EVA band @ 1242cm-1

δCH3 bitumen band @ 1376cm-1

1242cm-1

1600cm-1

Mouillet et al, BLPC 2000

965cm-11376 cm-1

γCH SBS band @ 965cm-1

δCH3 bitumen band @ 1376cm-1

Colors = various levels of polymer concentrations

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ELASTOMER MODIFIED BINDERS

Microstructure of a Microstructure of a crosslinked PmB crosslinked PmB

(Styrelf®)

3 D Network3 D Network(N(N--hexane washed)hexane washed)

UV Fluorescence

0,34

0,36

FTIR Microscopy

Fine dFine dispersion of the in situ ispersion of the in situ crosslinked polymercrosslinked polymer

- SPE/BTM-JPP-15-07-2010

Polymer-modified Bitumens aging After L. Lapalu, J-P. Planche, V. Mouillet, P. Dumas,

F. Durrieu – Eurobitume Eurasphalt Congress May 2004

Collaboration between TOTAL and LCPC

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Oxidation cell

FeaturesFeaturesTemperature sweepTemperature sweep

Oxidant or neutral gasOxidant or neutral gasHeating rateHeating rate

Top view

Gas InletGas OutletGage

GageD

Sample

Side section

To the IR detector

Gas Outlet

Gas Inlet

Sample

Oxi

datio

nt

IR Indices calculation

To To continuouslycontinuously visualize and analyze phases chemical evolutionvisualize and analyze phases chemical evolution

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T=0’

T=90’

T=30’

T=60’

T=120’

0,9%

7,8%1,0%

8,1%1,0%

9,3%1,0%

9,4%1,1%

9,5%

Conditions : 130°C / Air

Increase in EVA concentration Increase in EVA concentration in polymer nodules (7.8 to 9.5 in polymer nodules (7.8 to 9.5 %)%)

Stability of EVA concentration Stability of EVA concentration in AC matrixin AC matrix

Oxidation kinetics in the cell – 6% EVA - Bc

Exchange of asphalt molecular species between phases according to their compatibility with polymer:

Concentration of the polymer network due to a lower EVA compatibility in the oxidized bitumen

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EVA mB microstructure evolution (after Durrieu et al)

Before ageingBefore ageing

Phase inversion @ 6% EVAPhase inversion @ 6% EVA

EVAEVA swollen by slightly swollen by slightly condensed aromatics condensed aromatics substituted by aliphaticssubstituted by aliphatics7.6%

0.8%+ 6% EVA

7.6%7.6%7.6%

0.8%+ 6% EVA

7.6%

0.8%+ 6% EVA

7.6%7.6%

After RTFOT+PAV ageingAfter RTFOT+PAV ageing

Increase in EVA content in Increase in EVA content in the nodulesthe nodules

Stability of aromatics, but Stability of aromatics, but decrease in aliphatics and decrease in aliphatics and condensedcondensed

migration of the fraction migration of the fraction involved in EVA swelling to involved in EVA swelling to the surrounding matrixthe surrounding matrix

9.2%

0.4%+ 6% EVA

9.2%

0.4%+ 6% EVA

9.2%

0.4%+ 6% EVA

9.2%

0.4%+ 6% EVA

9.2%

0.4%+ 6% EVA

9.2%

0.4%+ 6% EVA

9.2%

0.4%+ 6% EVA

Validation of the oxidation cell !

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Homogenization of SBSHomogenization of SBS

Decrease in SBS in Decrease in SBS in polymer nodulespolymer nodules

Increase in SBS in AC Increase in SBS in AC matrixmatrix

Partial degradation of the polymer network

leading to a homogenization of the SBS copolymer distribution in the oxidized binder

T=120’

2,9%

6,9%

T=0’12,2%

0,6%

T=30’

0,6%

12,2%

T=60’

0,7%

11,8%

T=90’

1,5%

11,1%

Conditions : 130°C / Air

Oxidation kinetics – 6% SBS - Bc

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Crosslinking PmB

• Improvement of PMA rheological properties imparted by the crosslinking reaction on unaged binder...

0

30

60

90

1E+01 1E+03 1E+05 1E+07 1E+09G* (Pa)

Bc-SBSlin (3%)Bc-Styr1 (3%)

0

30

60

90

1E+01 1E+03 1E+05 1E+07 1E+09G* (Pa)

Bc-SBSlin (3%)

Bc-Styr1 (3%)Bc-SBSlin (3%) after RTFOT+PAV

Bc-Styr1 (3%) after RTFOT+PAV

...and after ageing• the polymer and the matrix remain compatible after ageing

elasticity on a wider temperature range

0

30

60

90

1E+01 1E+03 1E+05 1E+07 1E+09G* (Pa)

Bc-SBSlin (3%)Bc-Styr1 (3%)Bc-SBSlin (3%) after RTFOT+PAVBc-Styr1 (3%) after RTFOT+PAVBc-Styr1 (6%) after RTFOT+PAV

t=0 min RTFOT + PAV aging

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PmB Aging: Impact on low temperature properties

•• mm--value good indicator of binder agingvalue good indicator of binder aging•• Modification effect:Modification effect:

•• Positive for SBS crosslinked PmB, Negative for EVAPositive for SBS crosslinked PmB, Negative for EVA

D T iso 0.3

0

2

4

6

8

D T

iso

(°C

)

Bc 3 XLl3 XLr6 XLl6 XLr3 SBSl3 SBSr6 SBSl6 SBSr3 EVA6 EVA3 EBA 6 EBA

D Tiso 300

BBR parameters evolution vs. RTFOT+PAV aging

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Low temperature properties – Fracture mechanics

The Mode-I Fracture Test

Environmental chamber at Environmental chamber at --20°C20°CCutting of the rupture faces for Cutting of the rupture faces for CSEMCSEM or or ESEMESEM observationsobservations

TestTest

Speed = 0.6 Speed = 0.6 mm.minmm.min--11

T = T = --20°C20°C

KKICIC = failure load = failure load ×× f (span, crack length, sample dimensions)f (span, crack length, sample dimensions)

AfterAfter Lapalu et al, Eurobitume 2000Lapalu et al, Eurobitume 2000

45 - SPE/BTM-JPP-15-07-2010

Fracture mechanisms

Neat bitumen (KIC = 48 kPa.m1/2)

No topographic contrastNo topographic contrastBrittle rupture Brittle rupture low Klow KICIC

6% EVA-28 blend (KIC = 74 kPa.m1/2)ESEM observation at -5°C

50 µ

m

Polymer glassy at testing temperaturePolymer glassy at testing temperature

PolymerPolymer--rich particles pulledrich particles pulled--out without out without deformationdeformation

Fracture mechanism governed by Fracture mechanism governed by the (poor) adhesion between the (poor) adhesion between phases phases low Klow KICIC

AfterAfter Lapalu et al, Eurobitume 2000Lapalu et al, Eurobitume 2000

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PhysicalPhysical blendblend 4% SBS4% SBS**

22

(K(KICIC

= 107 kPa.m= 107 kPa.m1/21/2))

4% SB 4% SB Crosslinked binder Crosslinked binder (K(KICIC

= 113 kPa.m= 113 kPa.m1/21/2))

CLSM observation at -165°C

PParticle pullarticle pull--out (crack deflection) without (crack deflection) withPlastic Deformation of SBS NodulesPlastic Deformation of SBS Nodules

SBS in rubbery state SBS in rubbery state High KHigh KICIC

AfterAfter Lapalu et al, Eurobitume 2000Lapalu et al, Eurobitume 2000

Fracture mechanisms

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Lessons learned – a few tips

N°1: Humility

Critical eye

Think global

Use the right tool

Think out of the box

Meet and work with the right peopleCross-fertilizationCompetences

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Conclusions – Key issues

Thermal historyComparing binders in the same physical state to measure intrinsic propertiesAssociations - interactionsCrystallization – precipitationMelting – solubilizationPhases – multiple – exchanges – molecule transferSwellingReactions

OxidationCross-linkingGelling…

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Maltenes

Structural model of asphalt cements

Crystallized Fractions

Resins

Asphaltenes

Colloidal Suspension of asphaltenes in a maltene matrix

And what else ?

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A few perspectives

There are powerful tools available to look at the fundamentals

Atomic force microscopy

Nano indentation

DSR - MSCRT

Modulated DSC

FTIR, ESEM microscopies

…

Let’s try to use them and interpret the results properly!

51 - SPE/BTM-JPP-15-07-2010

Acknowledgements

So many people over the years…

Total group and co-workers

France: P. Claudy, D. Martin, V. Mouillet, D. Lesueur, C. Such, C. De La Roche, B. Brûlé, JM Létoffé, F. Rondelez

US: D. Anderson and his band, G. King, J. D’Angelo, J. Youtcheff, J. Brannthaver, C. Petersen R. Robertson and the WRI team

Europe: O. Harders, Pr. Neuman, S. Brown, M. Partl, D. Sylbislki, W. Arand, TU Delft team

And all I’ve forgotten: please forgive me!