1. Fly ash: Looking beyond the conventional use
S. K. Nath, T. C. Alex, R. Kumar & Sanjay Kumar
CSIR-National Metallurgical Laboratory, Jamshedpur

2. What is Fly ash
A by-product or the finely divided residue resulting from the combustion of pulverized coal in thermal power plants.

3. Potential of Fly Ash A alumino-silicate material
Fine PSD with good flow ability
Combination of crystalline and glassy phases
Pozzolanic characteristic
Good durability
Refractory properties

4. Waste to Resource The Changing Mindset
With right process you can turn it into a useful product
Waste is a resource, but in the wrong place
The Changing Mindset

5. Fly Ash
Success stories

6. Bandra Worli Sea Link used
State of the Art
Milwaukee Art Centre, USA
Bandra Worli Sea Link used
HVFA concrete
BAPS Temple, Chicago
UTAH State
Capitol Building

7. Ample scope for new applications and technology
Fly ash Utilization in India
Better than Global Utilization trend
Global Utilization : 39%
Ample scope for new applications and technology

8. Conventional Fly ash Utilization (%)
Around 72% Fly ash is used in Cement & Building Materials

9. Fly Ash Research: Global Trend

10. Fly Ash Utilization in non-conventional way
Geopolymer
Ceno-sphere separation
Extraction of heavy metals
Ceramic products
High performing Composites
Wood & ply-wood substitutes
Light weight insulating material
Pre-processing

11. 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

12. Domain of Fly ash R&D at CSIR-NML

13. Green Process & Technology using Geopolymerization of Fly ash

14. Geopolymerization Geopolymer.........
Synthetic alkali alumino-silicate material
Mn [ – (SiO2)z – AlO2 ]n . wH2O
M : Alkaline element,
z : 1, 2 or 3, and
n : Degree of polymerization
Geopolymer can be described by the general formula

15. Why Geopolymer … Simple process Wide range of applications
80% less CO2 generation than OPC
Low energy & water consumption
Better durability & longevity
Qualifies as GREEN

16. Excited Examples: Geopolymer Concrete
Geopolymer concrete sleepers of operating railway, St-Petersburg – Moscow were placed in 1988 and operational.

17. Geopolymer Concrete Geopolymer in Airport runway
>20 MPa strength in 4 hours

18. Geopolymerisation of fly ash

19. Why Fly Ash is Suitable ?? <100 µm particle size Flow behaviour
Si-Al ratio 1.6 – 2.2
>30% glassy phase
Synthetic material

20. Suitability in Indian Context
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%,

21. CSIR-NML Research on Fly Ash Geopolymer

22. Self glazed tiles Low temperature processing
No additional process for glazing
Properties
Values
Dimension tolerance
Straightness of sides
Surface flatness
Water absorption, %
Moh’s hardness
Compressive strength
0.5%
14-16 5
>150 kg/cm2
Patent : 2626/DEL/2005, 30/09/2005 and 728/DEL/2006, 30/11/2005

23. Paving blocks
Synergistic Utilization of fly ash, BF slag, COREX slag, steel slag, zinc slag and kiln dust
Ambient temperature processing
Ready to use in 7 days
Product confirms IS-15658:2006 specification
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

24. Lab Scale to Pilot Scale

25. Geopolymer pilot plant – 1st in India
Supported by FAU- Department of Science & Technology
Fully automatic, with ~4 ton/shift capacity
Can produce different shapes paving blocks
Uses vibration, or hydraulic pressing or combination of both
A step forward in translating process into technology

26. Pre-processing of fly ash

27. Methods 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

28. Air Classification using ATP50
High speed air classifier with max rotation speed 20000, can classify very fine fractions also

29. Use of different size fraction in PPC

30. 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

31. Mechanically Activated
Fly Ash

32. 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

33. Strength Development in cement

34. MA Fly ash in Geopolymer
X50 ~ 5 μm
X50 ~ 3 μm
X50 ~ 36 μm
60 oC

35. Very high (120 MPa) strength
Geopolymer Cement
Very high (120 MPa) strength

36. Ceramics using Fly Ash

37. Wear Resistant Ceramics
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
Fly ash (30-40 wt% ) based wear resistance ceramics
substitute for high alumina based ceramic tiles

38. Refractory Bricks Properties Refractory brick IS-6
4/16/2017
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)
CSIR-NML

39. Patent No. DEL/1800/96, 005NF and 13005NF 1998/03
Ceramic Tiles
Produced at 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

40. We are caring for environment
Thank You
We are caring for environment

43. Fly ash Utilization: A Giant Leap
Year 2009
Generation : 6.5 billion tonnes
Utilization : 39%
Source: ACAA

44. Geopolymer as Products
Blended cements for structural applications
Enhanced acid and fire resistant cements
Toxic waste encapsulation
Advanced composites (high temperature ceramic)
Adhesives

45. Commercial Realty
Zeobond, Australia is making geopolymer concrete, using fly ash as one of the component

46. Geopolymer Pilot Plant: 1st in India
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

47. Immense Application Potential
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

48. Fly Ash, Geopolymer & Sustainability
Low cost
Easily available
Good properties
Geopolymer
Simple processing
Low energy consumption
Low CO2 generation
Low water requirement
Fly ash
Towards Sustainability

49. Reactivity of MA Fly ash

50. 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
Grinding and Mechanical Activation
Grinding time, h
Degree of dispersion
 E =  Eu -  (e as) = sWz
zWz =  E = e as
sWz =  E =  (e as)
Agglomeration
Aggregation
Rittinger Stage
z = efficiency of grinding
Wz = work expended during grinding
E = change in bonding energy due to grinding
e = specific surface energy
as = specific surface area

51. Mechanical Activation Devices

52. TVA Coal Ash Pond Rupture- 2008
-40-acre pond holding coal combustion waste for a Tennessee Valley Authority (TVA) steam power plant ruptured
-largest coal slurry spill in U.S. history
-contained 2.6 million cubic yards of fly ash and bottom ash
-heavy rains and freezing temperatures could be to blame

53. Paving 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,
A joint outcome of CSIR-NML & Tata Steel Collaboration
Paving Blocks
Cement based
Steel slag based
Total CO2 generation / ton kg
(from firing of cement)
kg (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

54. What are Supplementary Cementing Materials
What are Supplementary Cementing Materials? Pozzolan – a siliceous or alumino-siliceous material that, in finely divided form and in the presence of moisture, chemically reacts at ordinary temperatures with calcium hydroxide (released by the hydration of Portland cement ) to form compounds possessing cementing properties A hydraulic cement reacts chemically with water to form compounds (hydrates) that have cementing properties – e.g. Portland cement

55. Why Geopolymer … Cement type Manufacturing temperature
Energy consumption
CO2 emission
Portland °C
100
Glass
750°C-1350°C
64 (-36%)
35 (-65%)
Carbunculus™
nat °C
30 (-70%)
20 (-80%)
Source:

56. Potential substitute for natural granite
Synthetic Granite Tiles
Potential substitute for natural granite
Very dense
Macro defects free body
Excellent mechanical properties
Pat. No. DEL/1800/96