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EmulsionsTac k Co at to Ch ip Seal
Danny Gierhart, P.E.
Regional Engineer Asphalt Institute
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Emulsion Properties
Storing, Handling, andSampling
Common Uses of AsphaltEmulsions
Overview
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What is an asphalt emulsion?
Microscopic asphaltdroplets suspendedin water.
Mostly about 5 m indiameter, rangingfrom 1-20 m
Emulsifiers orsurfactants holdthese droplets insuspension.
100 micron/0.1mm
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Negatively- Charged Emulsions areclassified into 3 main types
RS (Rapid Setting)
MS (Medium Setting)
SS (Slow Setting)
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CRS (Rapid Setting)
CMS (Medium Setting)
CSS (Slow Setting)
Positively- Charged Emulsions are alsoclassified into 3 main types
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Additional Nomenclature
QS = Q uick SetHF = High Float1 = Binder residue = 60% Minimum
2 = Binder Residue = 65% Minimumh = Hard Pen Asphalt Bases = Soft Pen Asphalt Base or sometimes
Solventl and/or p = Latex and/or Polymer
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Emulsifier HeadLoves WaterHates Oil
Emulsifier Tail
Loves Oil
Hates Water
Asphalt Emulsifier
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Emulsifier Orientation at the Asphalt/WaterInterface
Opposite charges attractand same charges repel
Surface charge determined byemulsifier type and water pH
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Stabilization of Asphalt Droplets
+ + +++ +
Cationic emulsion-electrostatic repulsion prevents close approach ofdrops
no charge- droplets can come into contact and coalesce
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Anionic emulsion-electrostatic repulsion prevents close approach ofdrops
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Aggregate Charge
Limestone
Dolomite
Basalt
Granite
pos. negative
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Anionic emulsions(negatively charged)typically bond best withpositively chargedaggregates (limestones).
Cationic emulsions(positively charged)typically bond best withnegatively chargedaggregates (granites,sandstones, basalts).
Asphalt Emulsions
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Slowest Fastest
Emulsifier / Emulsion Reactivity
CSS CQS HF CMS CRS
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Larger particles settle faster Denser particles settle faster Low viscosity, Low residue emulsions are liable to settle Settlement is less in hot storage temperature The opposite is called creaming If unchecked settlement can be very hard to re-disperse.
Asphalt Emulsion Storage and Handling
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Hard water, pH changes, or contamination can reducethe charge on the droplets
When charge is insufficient to keep particles apart thenthey stick together (flocculation)
Flocculation may be reversible or lead to coalescence. High shear can also force particles together
Asphalt Emulsion Storage and Handling
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Old Material
Old material fromlast season will
not work well. A small amount ofold material willcontaminate aload of newmaterial.
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Temperature Problems
Dont overheatemulsions
(Distributors) Dont allowemulsions to freeze(ever)
Dont add cold waterto emulsions
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Tanker and Distributor Contamination
Dont Mix Hot Asphaltswith Emulsions
Dont Mix Cationic and
Anionic Dont Mix Old and New Dont Mix Emulsions
with sealers
Dont Mix Emulsionswith other chemicals,salts, etc.
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Job Site Storage of Emulsions
Try to order so allmaterial is usedevery day
Fresher is better Less exposure to
air is better Clean out all
storage tanks overthe off season
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Testing and Sampling
Only good samplefrom the emulsion
storage tank Samples must behandled correctlyand tested quickly
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AASHTO T 40 - Sampling Containers
Allowable containers: Anionic Emulsions - wide-mouth plastic or
glass jars or bottles.
Cationic Emulsions - wide-mouth plastic jars or bottles or wide-mouth cans withscrew caps.
Containers need to be new, not washed,
rinsed, or wiped with an oily cloth.
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Major Uses of Asphalt Emulsions
Chip Seal Sand Seal Slurry Seal Micro surfacing Cape Seal Fog Seal Scrub Seal Penetration
Macadam
Surface Treatments
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Major Uses of Asphalt Emulsions
Cold In-Place Full Depth
Reclamation Hot In-Place
Asphalt Recycling
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Major Uses of Asphalt Emulsions
Tack Coat Prime Coat Dust Palliative Crack Fill Cold Mix Paving Maintenance
Patch
Other Applications
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