Transcript Document

Presented by:
Ankit Shrivastava
G Sai Anvesh
Vishal Vinit
Sai Nikhil Thirandas
Aravind Kumar Dammu
09CE1019
09CE3002
09CE1044
09CE1040
09CE3016
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BITUMEN
 Bitumen is a black, oily, viscous
material that is a naturallyoccurring organic byproduct of
decomposed organic materials.
 It is sticky,thick,Tar like form of
petroleum derived from
polycyclic aeromatic
hydrocarbon
General uses of Bitumen:
• Constructions of roads, runways and
platforms.
• Water proofing to prevent water seepage.
• Mastic floorings for factories and go-downs.
• Canal lining to prevent erosion.
• Dump-proof courses for masonry.
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Bitumen plays a vital role in road construction typically as binder.
Application condition requires bitumen to behave as mobile liquid.
There are three ways to reduce its viscosity:
•Heat it
•Dissolve it in solvents
•Emulsify it.
In heating it involves some:
•Energetic
•Environmental and
•Health problems
As process is inefficient and involves
Loss of heat and even fumes causing
air pollution
In case using solvents:
We make use of volatile dilatants like kerosene petroleum which adds to its cost
although viscosity get reduced as it is uneconomical.
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BITUMEN EMULSIONS
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What are emulsions?
An emulsion is a dispersion Of small droplets of one liquid
in another liquid.
Emulsions can be formed by any two immiscible liquids, but
in most emulsions one of the phases is water.
Oil-in-water (O/W) emulsions are those in which the
continuous phase is water and the disperse (Droplet) phase is an
“oily” liquid.
Water-in-oil (W/O) “inverted” emulsions are those in which the
continuous phase is an oil and the disperse phase is water.
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Types of emulsions:
(a) O/W emulsion,
(b) W/O emulsion,
(c) multiple W/O/W.
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BITUMEN EMULSION
Bitumen Emulsion is a 2-phase system consisting of
•Bitumen
•Water
•Other Additives
•The bitumen is dispersed throughout the water phase in form of discrete globules, held
in suspension by electrostatic charges stabilized by emulsifier
•The Emulsion contains 40-75% of bitumen,.1-2.5%emulsifier,25-60%water and other
ingredients
•Typically of .1 – 50 µm in diameter.
•It is mainly dark brown in color after breaking changes to black.
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WHY BITUMEN EMULSIONS ?
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Primary objective is to use for road surfacing without much
heating.
As main advantages this improves the handling of bitumen at
room temperature.
Promotes surface interactions .
Its mixture with the aggregate attains full strength.
Economical and saves energy .
Reduced atmosphere pollution.
Water can also added before use to dilute as per requirement.
Rains can not effect it at the time of use and after use.
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Types:
Bitumen emulsions can be divided into four classes:
1) Cationic emulsions.
2) Anionic emulsions.
3) Non-ionic emulsions.
4) Clay-stabilized emulsions.
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The first two are most widely used
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Cationic emulsions
 If an electric potential is supplied between two
electrodes immersed in an emulsion containing
positively charged particles of bitumen, they will
migrate to the cathode.
 This emulsion is said to be cationic.
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Anionic emulsions
 If an electric potential is supplied between two
electrodes immersed in an emulsion containing
negatively charged particles of bitumen, they will
migrate to the anode.
 This emulsion is said to be anionic.
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Non-ionic emulsions
 If the bitumen particles in the emulsion are neutral,
then they will not migrate to any of the pole.
 These type of emulsions are NON-IONIC.
 Mainly used in road ways.
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Clay-stabilized emulsions
 These are mainly used for industrial applications.
 In these materials, emulsifiers are fine powders, often
natural or processed clays and bentonites.
 Particle size is very much less when compared with the
bitumen particles in emulsions.
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Manufacture of Bitumen emulsions
 Bitumen emulsions can be manufactured using batch
process or continuous process.
 Bitumen emulsions are made in continuous inline
processes involving dispersing technologies like rotor
stators, colloidal mills and static mixers.
 High shearing forces are required for producing
emulsions.
 Colloidal mills contain high speed rotors.
 Hot bitumen and emulsifier are fed simultaneously
into colloidal mill.
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Manufacturing conditions
 The speed of rotors is in the range of 1000-6000
revs/min.
 Bitumen is generally heated to temperature of 100-140
degree celsius.
 The viscosity of the bitumen is kept less than 2 poise.
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Figure 2. Schematic diagram of a bitumen emulsion plant
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 As an alternative to colloid mill, a static mixer can be
used.
 This contains no moving parts.
 The high shear necessary to produce an emulsion is
generated by pumping the input materials at high
speed.
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Role of Emulsifiers in Bitumen Emulsion
 An emulsifier is a substance which stabilizes an
emulsion by increasing its kinetic stability.
 In order to be effective, it must be water soluble and have a
balance between hydrophilic & litho phobic properties.
 In emulsion, the ionic portion of emulsifier is located
at surface of the bitumen droplet by hydrocarbon
chain.
 The ionic portion of the emulsifier imparts a charge to
the droplets themselves and counter-ions diffuse into
the water.
 As the concentration of the emulsifier increases, the
particle size of the emulsion is reduced.
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•In Simple emulsifier( R  NH3Cl  ) ‘R’ represents the
Hydrophobic (Lithophilic)portion of emulsifier
•Usually long chain hydrocarbon consisting of 8 to 22
carbon atoms.
•The Hydrophilic can consist of amines , sulphonates ,
ether, alcohols.
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Emulsifier functions
 It performs various functions within bitumen
emulsion.
1. Makes emulsification easier by reducing the
interfacial tension between bitumen and water.
2. Stabilize the emulsion by preventing coalescence of
droplets.
3. Dictates its performance characteristics such as
setting and adhesion .
4. Emulsifier also decreases rate of flocullation.
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Types of Emulsifier:
1. Anionic
2. Cationic
3. Non-ionic
Defined on basis of polar bonds
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 Cationic emulsifier-Electrovalent and Polar head
group is positively charged & imparts positively
charged to the surface of the bitumen droplets.
 It is prepared by dissolving hydrocarbon amines in
acids


E.g. R  NH 3 Cl

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 Anionic emulsifier-Electrovalent and Polar head group
is negatively charged & imparts negatively charged to
the surface of the bitumen droplets.
 It is produced by dissolving fatty acids in sodium
hydroxides.
 E.g. R  COO Na 
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 Non ionic –The hydrophilic head group is covalent ,
polar and dissolves without ionization.
R  COO(CH 2CH 2O) X H
Note-There are products with amphoteric head
group character which may adopt positive or
negative charges depending on pH
.
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Properties of bitumen emulsion
It is stable under transportation ,storage &application condition.
But it may break soon after application.
It may have low viscosity
It may flow due to irregular spraying but not due to road
irregularities
Important properties of Bitumen emulsion:
1.
Stability
2. Viscosity
3. Breaking
4. Adhesivity
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Emulsion stability
 This property indicates the resistance ability to change
properties over time. As stability is very important in
storage ,transport & use.
 Stable emulsion will change over time slowly.
 Reason for instability can be physical or chemical
process.
 As emulsion is a example of colloidal system in non
equilibrium state. If system reaches to equilibrium
Emulsion will go through several process like
flocculation, sedimentation, and coalescence leading
to instability of emulsion
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Fig: Schematic view of some of destabilizing processes
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Emulsion Viscosity
 The viscosity of the bitumen emulsion is important for
pumping and transportation.
 In some applications, for example surface dressing,
bitumen emulsion is sprayed on the road. In this case
the viscosity is critical. As It should be low enough to
permit even spraying but at the same time high
enough to prevent run-off, once it is sprayed on the
road.
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Emulsion breaking
Bituminous emulsions are designed to “break”
deliberately in contact with moist aggregates, releasing a
binder film on and between the mineral aggregates.
There can be two kind of breaking:
1. Breaking of anionic bitumen emulsions
2. Breaking of cationic bitumen emulsions
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Breaking of anionic bitumen emulsions:
It involves the substantial removal of water.
Mainly by evaporation but also by absorption through surfaces in
contact, particularly those of mineral aggregates.
Breaking of cationic bitumen emulsions:
For cationic emulsions a significant factor which contributes
towards the breaking, in addition to removal of water, is a
physiochemical effect which involves adsorption of positively
charged emulsifiers on to negatively charged surfaces in contact,
thus assisting in the destabilization of the emulsion.
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Emulsion adhesivity
 The physical-chemical adsorption of bitumen and surfactant
onto the mineral surface is governed by Vander Waals attraction
forces, electrostatic forces or covalent and electrovalent bindings,
and responsible for the film adhesion.
 To optimize the bitumen adsorption on substrate, surfactant
concentration should be slightly lower than the critical micelle
concentration (CMC), nevertheless surfactant concentration
higher than CMC is necessary to increase the stability of the
unstable thermodynamic emulsion. Ionic surfactant can adsorb
on slightly charged substrates. Non-ionic surfactants adsorb on
mineral surfaces mostly by hydrogen bonding or Vander Waals
attractive forces. The adsorption of surfactant changes the
hydrophobic hydrophilic behaviour of the substrate, thus acting
on the adhesion of the bitumen.
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Uses of Bitumen emulsion
 Crack Filling: To stop entering water in structural
layer of pavement Bitumen emulsions preferably
containing rubber are used as they are inexpensive and
effective.
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Grouting: It is the method of construction or stabilizing of
road surfaces and footpath. Emulsion is applied to compacted
dry aggregate and due its low viscosity it penetrates through
void structure of the aggregate.
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 Soil Stabilization: For agricultural land where fresh
top soil is susceptible to surface erosion ,bitumen
emulsion can be used as binding agent also helps in
retaining soil moisture & improving thermal
insulation
 Slip layer & concrete curing: Bitumen emulsions are
used to create a membrane between layers of concrete
to retain strength of upper layer by preventing water
seepage into lower layers by avoiding rigid adhesion.
Also it is sprayed on top surface to avoid evaporation of
water.
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CONCLUSION
It has been given us possibility to apply wide range of
new technologies and methods for road construction,
repair and keeping. And most important thing is that
it is all inexpensive and do not affect environment
However continuous development and learning how to
make bitumen-emulsions which would fit with local
conditions, materials, technology requirements and
standards must be carried on.
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