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BY
S. DHANABALANChief Manager / Civil
NLC Ltd.
NEYVELI
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What is Flyash?
Why utilize Flyash?
When to utilize Flyash?
How to manage Flyash?
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FLYASH What is F.A
Floating ACRONYM
Light Weight
YtterbiumAbrasive
SiliceousHazardous
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FLYASH
It is mineral residue got from the
combustion of Bituminous/Sub
Bituminous Coal
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Flyash Production
NLC 12 Lakh Tonnes
All India 180 million Tonnes
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Flyash Management
Effective Utilization
Safe Disposal
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Utilization Best Option
Cause pollution Air, Water and Land
Require Water
Occupies Land
Contains Heavy Metals
High Disposal Cost
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Historical Background
Use of ash dates back to 3000 BC.
Romans used volcano ash with horse
hair.
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s za onClassification Scientific
Way
Low value
Medium value High value
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Schematic Representation
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Characteristics of Flyash
CONTENTS LIGNITE FLYASH(%) COAL FLYASH (%)
L.O.I 1.0 TO 2.0 3-15
Sio2 45-59 40-64
Al2O3 23-33 15-29
Fe2O3 0.6-4.0 2-11
CaO 5.0-16.0 0.1-1.0
MgO 1.5-5.0 0.2-4.0
SO3 0-5.0 0.1-1.7
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Flyash as Pozzalone (PPC)
What is Pozzalone?
Pozzalone by itself is an inert material
But in the presence of water readily
reacts with lime to form hydrates.
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Mineral Composition Of
CementMINERALS COMPOSITION (%)
C3S 45-80
C2S 0-32
C3A 7-15
C3AF 4-14
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Reaction Of Cement With
Water
2 C3S + 6H C3S.H + 3CH
2 C2S + 4H C3s .H + CH
C3A + CH +18 H C4AH
C4AF + 3CH + 22 H C4AH + 3CFH
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Pozzalonic Reactions
3S + 3CH C3S.H
AL + 4CH + 15H C4A.19H
F + 3CH + 3H C3F.6H
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Codal Provisions
IS has prescribed certain minimum
physical and chemical parameters for
flyash for use as pozzalone in IS 3812.
Now IS has permitted use of FA upto35% in manufacture of PPC
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Characteristic Requirements Method of Test
Ref to
Siliceous
Pulverized
Fuel Ash
Calcareous
Pulverized
Fuel Ash
Annex IS No
Si02 + Al2o3 + Fe2o3 70 50 - IS 1727
Sio2 35 25 - IS 1727
Reactive Silica 20 20 B -
Mgo 5.0 5.0 - IS 1727
Sio3 3.0 3.0 - IS 1727
MgO 1.5 1.5 - IS 4032
Total Chlorides 0.05 0.05 - IS 12423
Loss in Ignition 5.0 5.0 - IS 1727
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Characteristics Requirements
Fineness-specific surface inm2/kg by Blaines permeability
method, &fin
320
Particles retained on
45 micron IS sieve (wet
sieving) in percent, Max
34
Lime reactivityAverage
compressive strength in
Nlmm3, Min
4.5
Compressive strength at
28 days in N/mm*, Miss
Not less than 80 percent
of the strength ofcorresponding plain
cement mortar cubes
Soundness by autoclave test
Expansion G_ specimen in
percent,Max
0.8
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Fly ash Bricks
Bricks are indispensible in construction
Used in Walls, Arches , Domes and
Roofs
Demand Supply Gap
Fertile top soil is exploited
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Process of Manufacturing Fly
ash Bricks
SINTERING Process
AUTOCLAVING Process
COLD Process
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Type of Fly ash Bricks
Cement Fly ash Bricks
FALG Bricks
Fly ash Lime Bricks
Clay Fly ash Bricks
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Strength Attainment in
Bricks 3CH + 2S C3S.3H
4CH + A + 15H C4A.19H
3CH + F + 3CH C3F.6H
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FA Brick Mfg In NLC
NLC is pioneer in FA brick manufacturing.
Flyash Lime Bricks manufactured manually
during 70s.
Cement Flyash Bricks using a manualpress during 90s.
Semi Automatic process to Mfg Flyash
Lime Gypsum Bricks from 1997. Flyash bottam ash,Cement bricks are now
manufactured.
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Advantages of FA Bricks
Better Dimensional Stability
Uniform Strength
Reduce Cost of Disposal
Low Mortar Requirement
Economical
Reduce Pollution
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Conclusion
Flyash is no more a waste material
Gained Momentum
In NLC all the dry collected Flyash is
utilized
More than 50% of the ash production
could be utilized in FA bricks and PPC
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THANK YOU
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