Emulsions 101Polymer-Modified

Emulsions for Chip Seals and Slurry/Micro. Apps.

MPPP MeetingOctober 25, 2007

Chris LubbersSr. Technical Service Engineer

BASF Corporation(704) 587-8145

christopher.lubbers@basf.com

Helping MakeProducts BetterTM

2

Outline

Asphalt emulsion primer

What are polymers?

Why polymers for asphalt emulsions?

Modification of asphalt emulsions

Polymer networks in asphalt emulsions

Impact on performance + properties

3

Asphalt Emulsions - Formulation

ComponentsAsphalt

Surfactant (surface active agents, emulsifiers)

Water

Mechanical energy (colloid mill)

Other IngredientsAdditives (calcium chloride, cutback agents,…)

Modifiers – Polymers

4

Dispersion of asphalt in waterWater – continuous phaseAsphalt – non-continuous or dispersed phase–Stabilized by surfactant

Surfactant emulsion class.

Cationic

Anionic

Nonionic

Asphalt Emulsions – Component Distribution

5

Asphalt DropletsAsphalt Droplets

0

2

4

6

8

0.1 1 10 100

Particle Size, μm

Volu

me

%

6

What are Polymers?

Comprised of many small moleculesPoly = manyMonomers = small molecules or repeat units

Monomers chemically react larger moleculesWater-based polymers – latex form (SBR)

Solvent-based polymers – pellets, bale (SB-,SBS)

Properties are determined by:Types and sequence of monomersMolecular weight

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Typical Monomers

C C

C C

H

H

H

H

H

H

Styrene

Butadiene

C CH H

H

H

HH

H

H

8

Polymers for Asphalt Emulsion Modification

Elastomer – Styrene-Butadiene Rubber - SBRLatex form – polymer particles dispersed in water

Random monomer addition – typ. 75/25 Bd/styrene

High molecular weight – 1,000,000 g/mole

– 13,900 Bd “mers”, 2400 styrene “mers”

Broad distribution – chains many different lengths

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Polymers for Asphalt Emulsion Modification

Elastomer – Polyisoprene – Natural RubberLatex form – polymer particles dispersed in water

Homopolymer of isoprene – harvested from trees

High molecular weight – 1,000,000 g/mole

Broad distribution – chains many different lengths

C CC C

H

H

CH3

H

H

H

Isoprene

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Polymers for Asphalt Emulsion Modification

Thermoplastic ElastomersStyrene-Bd-Styrene block copolymer – SB-, SBSMonomers blocked in polymer backbone

Typically 70/30 Bd/styreneLower molecular weight – 100,000 g/mole

1300 Bd “mers”, 288 styrene “mers”Narrow distribution – all chains similar length

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Polymers for Asphalt Modification

Thermoplastic Ethylene vinyl acetate (EVA) resin

Vinyl acetate content ~ 20% to 40%

Low Tg, high melt temp due to crystallinity

ThermosetGround tire rubber (GTR)

Mixtures of E-SBR, S-SBR, PBd, natural rubber

Depends on tire component

Tread, sidewall, innerliner (halobutyl),…

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Viscoelastic Behavior Cured Latex Modified Asphalt Emulsion

G* = f(T) = deform. resist.

AsphaltHigh G* at low T – brittleLow G* at high T – viscous ΔG*(80oC – 20oC) = 1000x

SBR PolymerLower G* at low T – flexibleHigher G* at high T – elasticΔG*(80oC – 20oC) = 10x

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

-60 -40 -20 0 20 40 60 80

Temperature, °C

Com

plex

Mod

ulus

[G*],

Pa

AAA-1 Asphalt

SBR Polymer

Low Tg

High Molecular Weight

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Polymer Modification of Asphalt Emulsions

Emulsify polymer modified asphalt

“Pre-modified” emulsion

Polymers – SBS, SB-, EVA

Higher mod. asphalt viscosity

higher asphalt + mill temp.

Exit temp. > 100oC

Heat exchanger, back press.

Polymer inside asphalt droplet

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Polymer Modification of Asphalt Emulsions

Add latex external to asphalt Methods

– soap batching

– co-milling – asphalt line

– co-milling – soap line

Polymers – SBR, NR latex

Lower asphalt process T

No special mill, handling

Polymer in water phase Continuous polymer film formation on curing

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Bitumen

Latex

Latex Modified Emulsion Cured Bitumen Emulsion

• Optimum for Fine Polymer Network Formation

Latex Polymer-Modified Asphalt Emulsion

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Chip Seal – Field Application

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Chip Seal Surface Treatment

Near Taos, NM

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CRS-2 vs.CRS-2P(LM) – Physical Props.

3 wt.% SBR latex polymer (on asphalt)

ResidueASTM D 6934 - Oven evaporation at 163oC

PolymerRaises SP, drastically increases ductility and ER

Test Method CRS-2 CRS-2PR&B Softening Point (oF) ASTM D 36 115 128Ductility (4oC, cm) ASTM D 113 21 150+Elastic Recovery (10oC, %) AASHTO T 301 5 60

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Chip Seal – CRS-2Early Strength Development

Water wicks agg. surface

Positive correlation early chip retentionagg. H2O absorptivity

50

60

70

80

90

100

A B C D E F G H

Aggregate Samples

% A

ggre

gate

Ret

aine

d

0.0

0.5

1.0

1.5

2.0

2.5

Wat

er A

bsor

ptio

n, %

Data provided by Paragon Technical Services

With Unmodified CRS-2

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Early Strength Develop. – CRS-2P ASTM D7000-04 - Sweep Test

50

60

70

80

90

100

A B C D E F G H

Aggregate Samples

% A

ggre

gate

Ret

aine

d

Unmodified CRS-23 wt% SBR Latex Mod.

Data Provided by Paragon Technical Services

Potential Chip Loss

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Sweep Testing – CRS-2 vs CRS-2PASTM D7000 - 04

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Latex polymers accumulate at optimum locationAct to glue aggregate together!!!

Chip Seal with Latex Modified CRS

Aggregate particles Emulsion Residue

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Curing of CRS-2(LM) Emulsions

CRS-2(LM) (Unstable)

CRS-2(LM)(Stable)

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Asphalt Emulsion ~ Surface Area

Surface area of asphalt= 1200cm2 (1.2x10-1m2)

(10inch x 20inch)

Material WeightAsphalt 2kg

Latex (65% solids) 90gCationic emulsifier 4.0g

HCl 3.0gWater 900g

MaterialNo of particles or molecules

Surface Area, m2

Asphalt 3.1x1013 600 20x30 mLatex (3% of asphalt) 4.7x1015 330 20x17 m

Cationic Emulsifier 1.2x1022

HCl 1.5x1022

Water 3.0x1025

~ 1 gal emulsion)

25

70%

75%

80%

85%

90%

Surf A Surf B Surf C Surf D

Chi

p R

eten

tion

–A

STM

D 7

000-

043% SBR Latex Polymer Modified CRS-2LM AC-5 (150 PEN) Asphalt

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Curing of CRS-2LM Emulsion

Water in asphalt emulsion wicks the aggregate surface.Order of migration = Water, latex particles, asphalt droplets

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Latex Polymer Distribution

Latex particles migrate together with water???Polymer rich regions around aggregate = NO

Waterwicking

CRS-2LM with Surfactant A

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Latex Polymer Distribution

Latex particles migrate together with water!Polymer rich regions around aggregate = YES

Waterwicking

CRS-2LM with Surfactant D

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Microsurfacing Operation

Cohesion Development<1 hrCohesion Development<1 hr1min<Mix Time<3 min1min<Mix Time<3 min

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Microsurfacing – High ADT + ESAL’s

AUTOBAHN

Paved in Oct. 2001Photo from Sept. 2003

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Microsurfacing Mix Formulation

• Blade Coating Operation• 2 m wide + <1 cm thick• 4-5 km/hour• Traffic within 1 hour

• Latex Polymer Binds • Asphalt • Fines to Aggregates

Aggregate

Emulsion

Water

Cement

Latex Polymer = 3% of Asphalt (1/4 of Cement)

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Microsurfacing – Polymer Morphology Field Application

5μm

Texas State Highway 84• Near Waco,TX• Paved in 1998 • Samples taken in 2001

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Cured Latex Polymer Network

Microsurfacing Latex Foam

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Wet Track Abrasion Loss – ISSA TB-100

SBR latex polymer50% reduction in loss

one hour soak 67% reduction in loss

six day soak

Surface of mixtougher more abrasion res.

Adhesion + water resistanceimproved

05

1015202530354045

Loss

(g/ft

2 )

Unmod. SBR

1 Hour 6 Day

3 wt% SBR (on asphalt)

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Microsurfacing Residue – SHRP Grade

64

70

76

82

0 10 20 30 40 50

Curing Time, day

Tem

p. a

t G*/s

in(δ

)=1k

Pa, °

C

Emulsion Only

Emulsion+Cement

Emulsion+Cement+SBR Latex

30 days Cured

60

65

70

75

80

85

90

Emulsiononly

+ Cement +3% Latex

Phas

e A

ngle

at G

*sin

(δ)=

1kPa

, deg

ree

Rut

ting

resi

stan

ce te

mpe

ratu

re, °

C

36

Advantages of Latex Polymer Network

Latex polymer honeycombs remain flexible

Absorb stresses without permanent deformation

37

Summary – Polymer Modified Emulsions

Chip seals•Early and long term chip retention • High temperature strength• Low temperature flexibility

Slurry seal and microsurfacing• Improved mix cohesion•Reduction in abrasion loss of aggregate•Resistance to deformation

Emulsions 101Polymer-Modified

Emulsions for Chip Seals and Slurry/Micro. Apps.

MPPP MeetingOctober 25, 2007

Chris LubbersSr. Technical Service Engineer

BASF Corporation(704) 587-8145

christopher.lubbers@basf.com

Helping MakeProducts BetterTM

39

Polymer Modified Emulsion + GTR Modified Asphalt Producers

Producer - Pre-Modified Emulsion (SB-,SBS)SEMMaterials

Producers - Latex-Modified Emulsions (SBR/NRL)SEMMaterials ~ Ralumac® – NRL – Microsurfacing

All States Asphalt + GTR for Hot Applied Chip Seals

Hudson Companies + GTR for Hot Applied Chip Seals

SuitKote

Vestal Asphalt

Midland Asphalt

Gorman Brothers

Peckham Industries