Polymer-Modified Emulsions for Chip Seals and · PDF fileTest Method CRS-2 CRS-2P ......
Transcript of Polymer-Modified Emulsions for Chip Seals and · PDF fileTest Method CRS-2 CRS-2P ......
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
Helping MakeProducts BetterTM
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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
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Asphalt Emulsions - Formulation
ComponentsAsphalt
Surfactant (surface active agents, emulsifiers)
Water
Mechanical energy (colloid mill)
Other IngredientsAdditives (calcium chloride, cutback agents,…)
Modifiers – Polymers
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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
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Asphalt DropletsAsphalt Droplets
0
2
4
6
8
0.1 1 10 100
Particle Size, μm
Volu
me
%
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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
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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)
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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
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Advantages of Latex Polymer Network
Latex polymer honeycombs remain flexible
Absorb stresses without permanent deformation
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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
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