What is Fly ash
A by-product or the finely divided residue resulting from the combustion of pulverized coal in thermal power plants.
A alumino-silicate material Fine PSD with good flow
ability Combination of crystalline
and glassy phases Pozzolanic characteristic Good durability Refractory properties
Potential of Fly Ash
Waste is a resource, but in the wrong place
With right process you can turn it into a useful product
Waste to Resource
The Changing Mindset
State of the ArtMilwaukee Art Centre, USA
BAPS Temple, ChicagoUTAH State Capitol Building
Bandra Worli Sea Link used HVFA concrete
Fly ash Utilization in India
Ample scope for new applications and technology
Better than Global Utilization trendGlobal Utilization : 39%
1. Geopolymer2. Ceno-sphere separation3. Extraction of heavy metals4. Ceramic products5. High performing Composites6. Wood & ply-wood substitutes 7. Light weight insulating material8. Pre-processing
Fly Ash Utilization in non-conventional way
Fly ash R&D at CSIR-NML
First research project on fly ash was carried out in 1968
Main activities started in 1994, focus on high value added ceramic products
National Seminar on Fly ash in 1999
Preprocessing of fly ash started in 2000, completed project on cement
Major activities on geopolymer started in 2004, pilot plant setup in 2011
MoU with C-FARM in 2009
Fly ash is one of the major activities under 12th Five year plan during 2012-2017
Green Process & Green Process & Technology using Technology using Geopolymerization of Geopolymerization of Fly ashFly ash
Simple process
Wide range of applications
80% less CO2 generation than OPC
Low energy & water consumption
Better durability & longevity
Qualifies as GREEN
Why Geopolymer …
Geopolymer concrete sleepers of operating railway, St-Petersburg – Moscow were placed in 1988 and operational.
Excited Examples: Geopolymer ConcreteExcited Examples: Geopolymer Concrete
Si-Al ratio 1.6 – 2.2
>30% glassy phase
<100 µm particle size Flow
behaviour
Synthetic material
Why Fly Ash is Suitable ??
Abundantly available Either free of cost or low cost material Cement making is of great concern due to
depleting natural resources and increasing CO2
generation 100% utilization of fly ash notification by MoEF,
Nov. 2009 Exploit the full potential of fly ash as source of
silica and alumina: >90% fly ash can be used in
many products Indian fly ash is suitable for geopolymerization The average ambient temperature in India is
27°C and average humidity is >50%,
Abundantly available Either free of cost or low cost material Cement making is of great concern due to
depleting natural resources and increasing CO2
generation 100% utilization of fly ash notification by MoEF,
Nov. 2009 Exploit the full potential of fly ash as source of
silica and alumina: >90% fly ash can be used in
many products Indian fly ash is suitable for geopolymerization The average ambient temperature in India is
27°C and average humidity is >50%,
Suitability in Indian Context
Patent : 2626/DEL/2005, 30/09/2005 and 728/DEL/2006, 30/11/2005
Self glazed tiles
Properties Values
Dimension toleranceStraightness of sidesSurface flatness
Water absorption, %Moh’s hardness Compressive strength
0.5% 0.5% 0.5%
14-165>150 kg/cm2
Low temperature processing
No additional process for glazing
Synergistic Utilization of fly ash, BF slag, COREX slag, steel slag, zinc slag and kiln dust
Paving blocks
Properties Pavement tiles
Compressive strength
(MPa)
Flexural strength (MPa)
Bulk density, gm/cc
Water absorption, %
Abrasion resistance, mm
20-40
5-7
2.8
6-7
0.7
Ambient temperature processing
Ready to use in 7 days
Product confirms IS-15658:2006 specification
Fully automatic, with ~4 ton/shift capacity
Can produce different shapes paving blocks
Uses vibration, or hydraulic pressing or combination of both
Supported by FAU- Department of Science & Supported by FAU- Department of Science & TechnologyTechnology
A step forward in translating process into technologyA step forward in translating process into technology
Geopolymer pilot plant – 1st in India
Processing methods
Principle Applications
Air classification Size classification based on shape, size and density of fly ash
Separation of different size fraction of fly ash
Separation of cenosphere
Triboelectric separation
Charge separation Separation of carbon
Mechanical activation
Increase in surface area, creation of bulk & surface defects
Increased utilization in blended cement
High strength geopolymers
Methods
Air Classification using ATP50
High speed air classifier with max rotation speed 20000, can classify very fine fractions also
Strength Development !!
Coarse fraction shows lot of un-reacted fly ash particles even after 28 day hydration
More reaction product in the fine fraction is the reason for strength development
What is Mechanical Activation
Changes that takes place during mechanical activation
Increase in surface area Stresses in solid structure Defects induced in the solid
structures Phase transformations Repeated welding of interfaces Fracture leading to dynamic
creation of fresh surfaces for reactions
Chemical reactions
Wear Resistant Ceramics
Fly ash (30-40 wt% ) based wear resistance ceramicssubstitute for high alumina based ceramic tiles
Excellent compressive strength
Very hard and dense
Excellent wear resistant properties
Can be used for wear resistant applications in pipelines, chutes, bunkers, hoppers, mills etc
Refractory Bricks
50% fly ash can be used
Equivalent of IS-6 fire-clay bricks
Sintered at lower temperature
Properties Refractory brick
IS-6
% AP 24.5 25.0 (max)
BD (g/cc) 1.9 2.0 (min)
CCS (Kg/cm2) 300 250 (min)
Al2O3 %Fe2O3 %
30.7 3.5
30.0 (min)2.0 (max)
Ceramic Tiles
Produced at 980-1050 C Improved scratch hardness
Better compressive strength
Satisfy EN specification
Possibility to use other waste in addition to fly ash
Patent No. DEL/1800/96, 005NF and 13005NF 1998/03
Fly ash Utilization: A Giant Leap
Year 2009
Generation : 6.5 billion tonnesUtilization : 39%
Source: ACAA
Geopolymer as Products
Blended cements for structural applications
Enhanced acid and fire resistant cements
Toxic waste encapsulation
Advanced composites (high temperature ceramic)
Adhesives
Zeobond, Australia is
making geopolymer
concrete, using fly ash as
one of the component
Zeobond, Australia is
making geopolymer
concrete, using fly ash as
one of the component
Commercial Realty
Provide valuable design and operational data for the setting up of a large size plant,
Assess the impact of variability of raw materials (fly ash, water etc) quality,
Fine tune operational parameters, Work out a more precise techno-economics for
the process, Act as demonstration unit and instill confidence in
potential user of the technology since the technology would be used in India for the first time,
Development of other geopolymer products since the plant has a modular character
Provide valuable design and operational data for the setting up of a large size plant,
Assess the impact of variability of raw materials (fly ash, water etc) quality,
Fine tune operational parameters, Work out a more precise techno-economics for
the process, Act as demonstration unit and instill confidence in
potential user of the technology since the technology would be used in India for the first time,
Development of other geopolymer products since the plant has a modular character
Geopolymer Pilot Plant: 1st in India
Area Applications
Civil engineering Low CO2 Fast setting cement, Precast concrete products
Ready mixed concrete
Building materials Bricks, blocks, pavers, self glazed tiles, acoustic panels,
pipes,
Archeology Repairing & restoration
Composite material Functional composite for structural ceramic application
Fire resistant material Fire and heat resistant fiber composite material
Refractory application Refractory moulds for metal casting, Refractory castables
Immobilization of toxic
materials
encapsulation of domestic, hazardous, radioactive and
contaminated materials in a very impervious, high
strength material
Others Paints, Coatings, Adhesive
Immense Application Potential
Low costEasily availableGood properties
Geopolymer
Simple processingLow energy consumptionLow CO2 generationLow water requirement
Fly ash
Towards Sustainability
Fly Ash,
Geopolymer
& Sustainability
Reactivity of MA Fly ash
0 10 20 30 40 50 60 70 80 90 1000
2
4
6
8
10
12
14 Temperature : 27 oCw/c ratio : 0.5
m
W
Time, h
VMFA25% AMFA25% VMFA50% AMFA50% IC-B (~ 20% FA)
Grinding and Mechanical Activation
Grinding time, h
Deg
ree
of d
ispe
rsio
n
E
=
E u -
(e a s
) =
sW
z z
Wz =
E
= e
as
sW
z =
E
=
(e a s
)
AgglomerationAggregationRittinger
Stage
z = efficiency of grindingWz = work expended during grindingE = change in bonding energy due to grindinge = specific surface energyas = specific surface area
What is Mechanical Activation
Changes that takes place
Increase in surface area Stresses in solid structure Defects induced in the solid
structures Phase transformations Localised and overall
thermal effects Repeated welding of
interfaces, and Fracture leading to
dynamic creation of fresh surfaces for reactions etc.
Chemical reactions
Paving Blocks from Industrial WastePaving Blocks from Industrial Waste
Combination of fly ash, steel slag and granulated blast furnace slag has been used,
Meet all the obligatory specification as per IS 15658: 2006,
Complied with the USEPA limit for leaching of toxic metals and is environmentally safe,
Paving Blocks Cement based Steel slag based
Total CO2 generation / ton 180 -200 kg(from firing of cement)
16 - 20kg (conversion of alkali carbonate into oxide)
Water requirement/ ton 300 liters 250 liters
Waste & by-products reuse/ ton
<75 kg >900 kg
Embodied energy/ kg 1.2 MJ 0.8 MJ
What are Supplementary Cementing Materials? Pozzolan – a siliceous or alumino-siliceous material that, in finelydivided form and in the presence of moisture, chemically reacts atordinary temperatures with calcium hydroxide (released by thehydration of Portland cement ) to form compounds possessingcementing properties
A hydraulic cement reacts chemically with water to formcompounds (hydrates) that have cementing properties – e.g.Portland cement
Cement typeManufacturing temperature
Energy consumption
CO2 emission
Portland 1450-1500°C 100 100
Glass 750°C-1350°C 64 (-36%) 35 (-65%)
Carbunculus™ nat. 20-80°C 30 (-70%) 20 (-80%)
Source: www.geopolymer.org
Why Geopolymer …Why Geopolymer …