MINOR PROJECT OF FLY ASH

1. OBJECTIVE – TO DETERMINE THE
COMPRESSIVE STRENGTH BY
REPLACING CEMENT WITH FLY
ASH

2.  ABSTRACT
 INTRODUCTION
 CLASSIFICATION
 PROPERTIES
o PHYSICAL PROPERTIES
o CHEMICAL PROPERTIES
o GEO – TECHNIACAL PROPERTIES
 APPLICATION
 BENIFITS OF FLY ASH
 ENVIRONMENTAL BENIFITS OF FLY
ASH USES IN CONCRETE
 DRAW BACK OF FLY ASH
 USES
 VARIOUS USES OF FLY ASH
 FLY ASH BRICKS/ BLOCKS
 CEMENT CONCRETE
 INGREDIENT CEMENTS
 EXPERIMENT

3. Abstract: The present paper deals with the
effect on strength properties of cement concrete
by using fly ash. The utilization of fly-ash in
concrete as partial replacement of cement is
gaining immense importance today, mainly on
account of the improvement in the long term
durability of concrete combined with ecological
benefits. Technological improvements in thermal
power plant operations and fly-ash collection
systems have resulted in improving the
consistency of fly-ash. To study the effect of partial
replacement of cement by fly-ash , studies have
been conducted on concrete mixes with 300 to
500 kg/cum cementious materials at 20%, 40%,
60% replacement levels. In this paper the effect of
fly-ash on workability, setting time, density, air
content, compressive strength, modulus of
elasticity are studied Based on this study
compressive strength v/s W/C curves have been
plotted so that concrete mix of grades M 20 with
difference percentage of fly-ash can be directly
designed

4. INTRODUCTION
Power plants fuelled by coal produce a significant
quantity of the electricity we consume in the world
today. But in addition to electricity, these plants
produce a material that is fast becoming a vital
ingredient for improving the performance of a wide
range of concrete products.
That material is fly ash.
Fly ash is also produced as a by product from
industrial plants using pulverized coal or lignite as
fuel for the boilers
Depending upon the source and makeup of the
coal being burned, the components of fly ash vary
considerably, but all fly ash includes substantial
amounts of
• silicon dioxide (SiO2)
(both amorphous and crystalline),
• aluminium oxide (Al2O3) and
• calcium oxide (CaO),
• the main mineral compounds in coal
bearing rock strata.

5. Classification
Class F fly ash
The burning of harder, older anthracite and
bituminous coal typically produces Class F fly ash.
This fly ash is pozzolanic in nature, and contains
less than 7% lime (CaO).
Possessing pozzolanic properties, the glassy silica
and alumina of Class F fly ash requires a
cementing agent, such as Portland cement,
quicklime, or hydrated lime—mixed with water to
react and produce cementitious compounds.
Alternatively, adding a chemical activator such
as sodium silicate (water glass) to a Class F ash
can form a geopolymer.
Class C fly ash
Fly ash produced from the burning of younger
lignite or sub-bituminous coal, in addition to having
pozzolanic properties, also has some self-
cementing properties. In the presence of water,
Class C fly ash hardens and gets stronger over

6. time. Class C fly ash generally contains more than
20% lime (CaO). Unlike Class F, self-cementing
Class C fly ash does not require an activator.
Alkali and sulfate (SO
4) contents are generally higher in Class C fly
ashes.
Properties of Flyash
Fly ash is a good material for a wide range of
applications viz. manufacture of cement, substitute
of cement in concrete, manufacture of bricks,
blocks, tiles, etc. It is highly useful as a geo-
technical material for construction of embankment
and reclamation of low lying areas, filling of
underground, open mines, use in agriculture and
reclamation of degraded / waste lands, etc.
The pozzolanic property coupled with lime
reactivity makes it very suitable for cementitious /
binding applications. Its geo-technical property
makes it a good substitute of soil and the presence
of required percentage of silica, alumina and iron
oxide etc. makes it suitable for sintered
applications. The suitability of flyash for various
applications is very safe due to very low levels of
heavy metals, toxic elements and radio nuclides in
flyash as well as its physical and chemical

7. properties being very close to the range of
common soils.
The following tables provide general range of
physical, chemical, geo-technical properties,
available major, secondary, micro-nutrients and
trace / heavy metals and radio-activity levels in
flyash and soil (source: Fly Ash India 2005 -
International Congress)
 Physical properties of flyash
Parameters
Fly Ash
Bulk Density (gm/cc) - 0.9-1.3
Specific Gravity -1.6-2.6
Plasticity -Lower or non-plastic
Shrinkage Limit -Higher
Grain size -Major fine sand / silt and
small per cent of clay
size particles
Clay (per cen) - Negligible
Free Swell Index -Very low

8. Classification (Texture) -Sandy silt to silty loam
Water Holding Capacity - 40-60 %
Porosity (per cent) - 30-65 %
Surface Area (m2 / kg) - 500-5000
Lime reactivity (MPa) - 1-8
Above properties are just approximation values.
Depending on the types of flyash these valyes
may vary
Chemical composition of fly ash and pond ash
Compounds (%) Fly Ash Pond Ash
SiO2 38-63 37-75
Al2 O3 27-44 11-53

9. TiO2 0.4-1.8 0-1
Fe2 O3 3.3-6.4 3-34
MnO b.d-0.5 b.d-0.6
MgO 0.01-0.5 0.1-0.8
CaO 0.2-8 0.2-0.6
K2 O 0.04-0.9 0.1-0.7
Na2 O 0.07-0.43 0.05-0.31
LOI 0.2-5.0 0.01-20.0
pH 6-8 6-8
bd: below detection limit,
LOI: Loss on Ignition Above properties are just an
approximation value. Depending on the types of
flyash these valyes may vary
value. Depending on the types of flyash these
valyes may vary

10. Geo-technical properties of fly ash
Parameter Range
Specific Gravity -1.6-2.6
Plasticity (per cent) -Lower or Non-Plastic
Maximum Dry Density (gm/cc) -0.9-1.3
Optimum Moisture Content (per cent)-18.0-38.0
Cohesion (kN/m2) -Negligible
Angle of Internal Friction(degrees) -30-40
Coeff. Of consolidation Cv(cm2/Sec) -1.75X10-5-
2 .01X 10-3
Compression index Cc- 0.05-0.4
Permeability (cm/sec) -8X10-6-7X10-4
Particle size Distribution
(per cent of materials)
1.Clay size fraction -1-10
2.Silt size fraction -8-85
3.Sand size fraction - 7-90
4.Gravel size fraction - 0-10

11. 5.
Coefficient of Uniformity - 3.1-10.7
Above properties are just an approximaAbove
properties are just an approximation value.
Depending on the types of flyash these values
may vary.
Fly Ash Applications
Fly ash can be used as prime material in blocks,
paving or bricks; however, one the most important
applications is PCC pavement. PCC pavements
use a large amount of concrete and substituting fly
ash provides significant economic benefits. Fly ash
has also been used for paving roads and as
embankment and mine fills, and it's gaining
acceptanceby the Federal government,
specifically the Federal Highway Administration.

12. Fly Ash Benefits
Fly ash can be a cost-effective substitute for
Portland cement in some markets. In addition, fly
ash could be recognized as an environmentally
friendly product because it is a by product and has
low embodied energy. It's also is available in two
colors , and coloring agents can be added at the
job site. In addition, fly ash also requires less
water than Portland cement and it is easier to use
in cold weather. Other benefits include:
• Produces various set times.
• Cold weather resistance.
• Higher strength gains, depending on
its use.
• Can be used as an admixture.
• Can substitute for Portland cement.
• Considered a non-shrink material.
• Produces denser concrete and a
smoother surface with sharper detail.
• Great workability.
• Reduces crack problems, permeability
and bleeding
• Reduces heat of hydration.

13. • Produces lower water/cement ratio for
similar slumps when compared to no
fly ash mixes.
• Reduces CO2 emissions.
Environmental benefits of fly ash use in
concrete
• Use of fly ash in concrete imparts
several environmental benefits and
thus it is ecofriendly. It saves the
cement requirement for the same
strength thus saving of raw materials
such as limestone, coal etc required
for manufacture of cement.
Manufacture of cement is high-energy
intensive industry.
• In the manufacturing of one tonne of
cement, about 1 tonne of CO2 is
emitted and goes to atmosphere. Less
requirement of cement means less
emission of CO2 result in reduction in
green house gas emission.

14. Fly Ash Drawbacks
Smaller builders and housing contractors are not
that familiar with fly ash products which could have
different properties depending on where and how it
was obtained.
For this reason, fly ash applications are
encountering resistance from traditional builders
due to its tendency to effloresce along with major
concerns about freeze/thaw performance.
Other major concerns about using fly ash concrete
include:
• Slower strength gain.
• Seasonal limitation.
• Increase in air entraining admixtures.
• An increase of salt scaling produced
by higher fly ash.
USES
The most common use of fly ash is as a partial
replacement for portland cement used in
producing concrete. Replacement rates normally

15. run between 20% to 30%, but can be higher. Fly
ash reacts as a pozzolan with the lime in cement
as it hydrates, creating more of the durable binder
that holds concrete together.
VARIOUS USES OF FLY ASH
 Fly Ash Bricks / Block
 Cement Concrete
 High Volume Fly Ash Concrete(HVFAC)
 Road construction
 Embankment / Back fills / Land development
 Controlled Low Strength Material(CLSM)
 Use in agriculture
 Mine filling
Fly Ash Bricks / Blocks
• Manufacturing process of clay fly ash bricks by
manual or extrusion process involves mixing of fly
ash(60%) with clay of moderate plasticity.

16. • The green bricks are dried under ambient
atmospheric condition or in shed to equilibrium
moisture level of below 3%.
• Dried bricks are fired in traditional bricks kilns at
1000°C ± 30°C with a soaking period of 5-7 hours.
These bricks have following advantages over
ordinary clay bricks:
Possess adequate crushing strength as a load
bearing member
. Have cement colour in appearance
Are uniform in shape
Smooth in finish and requires no plastering for
building work.
Are lighter in weight than ordinary clay bricks
Are cheaper than ordinary clay bricks
CEMENT CONCRETE
Ordinary Portland Cement (OPC) is a product of
four principal mineralogical phases.
These phases are Tricalcium Silicate- C3S
(3CaO.SiO2 ), Dicalcium Silicate C2S (2CaO.SiO2

17. ), Tricalcium Aluminate- C3A (3CaO.Al2O3 ) and
Tetracalcium alumino-ferrite - C4AF(4CaO. Al2O3.
Fe2O3 )
2C3 S + 6H ----> C3 S2 H3 + 3 CH
Water C-S-H Gel Calcium
Hydroxide
Above reactions indicate that during the hydration
process of cement, lime is released out and
remains as surplus in the hydrated cement. This
leached out surplus lime renders deleterious effect
to concrete such as make the concrete porous,
give chance to the development of micro- cracks,
weakening the bond with aggregates and thus
affect the durability of concrete.
• If fly ash is available in the mix, this surplus lime
becomes the source for pozzolanic reaction with
fly ash and forms additional C-S-H gel having
similar binding properties in the concrete as those
produced by hydration of cement paste. The
reaction of fly ash with surplus lime continues as
long as lime is present in the pores of liquid
cement paste.

18. Salient advantage of using fly ash in cement
concrete –
• Reduction in heat of hydration and thus
reduction of thermal cracks and improves
soundness of concrete mass.
• Improved workability / pumpabilty of concrete
• Converting released lime from hydration of OPC
into additional binding material – contributing
additional strength to concrete mass.
• Pore refinement and grain refinement due to
reaction between fly ash and liberated lime
improves impermeability.
• Improved impermeability of concrete mass
increases resistance against ingress of moisture
and harmful gases result in increased durability.
• Reduced requirement of cement for same
strength thus reduced cost of concrete.

19. Ingredient Cements
The ordinary Portland cement conforming to IS:
8112 was used. The specific surface of cement
used in this study was 60 N/mm2 and 295 m2/kg
respectivelly
Coarse Aggregate
The coarse aggregate from crushed basalt rock,
conforming to IS: 383 were used. The flakiness
and elongation
index were maintained well below 15%.
Fine Aggregate
The river sand and crushed sand was used in
combination as fine aggregate conforming to the
requirements of
IS: 383. The river sand was washed and
screened, to eliminate deleterious material and
over size particle.

20. Admixture
The high range water reducing and retarding
super plasticizer conforming to ASTM C-494,
Type G was used. The base of admixture used
in this study was sulphonated naphthalene
formaldehyde and
water reduction of admixture was around 20%.
Experimental Program
The test performed for testing the Compressive
strength of concrete using fly ash. Various cubes
are
made with various percentage of fly ash by
weight of cement, tested and then analyzed for
finding the effect of using fly ash.
Three concrete cube specimens for the test is
made for each M-15, M-20 and M-25 with 20%,
40% and 60% fly ash composition.
Compressive strength test is the most common
test conducted on hardened concrete as it is an

21. easy test to perform and also most of the
desirable characteristic properties of concrete
are qualitatively related to its compressive
strength. The compression test is carried out on
specimen cubical in shape .Prism is also
sometimes used, but it is not common in our
country. Sometimes, the compressive strength of
concrete is determined using the parts of beam
tested in flexure.
The cube specimen is of size 150*150*150mm.If
the largest size of aggregate does not exceed
20mm,100mm size cubes may also be used as
an alternative.
Procedure
First of all the mould preferably of cast iron,
thick enough to prevent distortion, is used to
prepare the specimen of size
150*150*150mm.

22. Fig 9:- Cube Mould.
During the placing of concrete in the
moulds it is compacted with the tamping
bar 16mm diameter,0.6mm long and bullet
pointed at lower end, with not less than 25
strokes per layer.
Then these moulds are placed on the
vibrating table and are compacted until the
specified condition is attained.

23. Fig
Vibrating
Table
The test specimens are stored in place
free from vibration, in moist air of at least
90% relative humidity and at a temperature
of 27degree +_2degree C for 24 hrs from
the addition of water to the dry ingredients.
After this period, the specimen is marked
and submerged water and kept there until
taken out just prior to test. The water in which
the specimens are submerged , are renewed

24. every 7 days .The specimens are not to be
allowed to become dry at any time until they
have been tested.
Fig - Cube After 7 Days Curing

25. Fig :- UTM
machine
during testing.
The cube is then taken out of the curing
tank and placed in the UTM machine (fig.12)
so to find the maximum load at which the
concrete fails by compression.

26. RESULTS
The results from the compression test are in
the form of the maximum load the cube can
carry before it
ultimately fails .The compressive stress can be
found by dividing the maximum load by the area
normal to it. The results of compression test and
the corresponding compressive stress is shown
in table
Let,
F= maximum load carried by the cube before
failure
A= area normal to load =___________ mm2
BLOCK A
Grade of concrete – M20 [1:1:5:3]
 Volume of concrete =_____________
 Weight =______________

27.  Volume ofcement concrete =_______
 Volume of Concrete = __________
 Volume of Concrete =________
 Cement = _____
 80% Cement = _________
 20% Fly ash =________-
Water = __________________
Sand = __________________
Aggregate = _______________
After 7 day
Initial load = _____________

28. Fail = ____________________
Therefore ,
Applied load = _________
Area =_______
Area ______
Strength of mould = __________________
Date of experiment _________
Reading date _________
BLOCK B
Grade of concrete - M20 [1:1.5:3]
60% Cement = _____

29. 40% Fly ash = ______
Strength of mould = _________
Date of experiment = _________
Reading date = _________
BLOCK C
Grade of concrete-M20 [1:1:5:3]
40% Cement = ________
60% Fly ash = _________
Strength of mould = ___________
Date of experiment =___________
Reading date =_______
Conclusion

30. India has a vast resource of fly ash
generation all across the country. This
material if segregated,
collected and used properly can solve the major
problem can solve the major problems of fly ash
disposal and reducing the use of cement, which
consumes lot of energy and natural resources.
Especially in India many organizations are
putting their efforts to promote the awareness of
fly ash concrete and its advantages. Nuclear
Power Corporation of India Ltd (NPCIL) is also
involved in R&D activities for development of fly
ash concrete and implementing it in construction
of nuclear power structure.
The experimental exercise has helped to study
the various properties of fly ash concrete and to
develop the mix design curves for concrete
mix proportioning with various percentages of
fly ash. Based on the studies conducted by
authors following conclusion are drawn on the fly
ash concrete.

31. 1. Use of fly ash improves the workability of
concrete. This phenomenon can be used
either the unit water content of mix or to reduce
the admixture dosage.
2. Density and air content of concrete
mix are generally unaffected with the
use of fly ash.
3. Normally use of fly ash slightly retards
the setting time of concrete, but it is
compensated by reduction in the admixture
dosage to maintain the same workability.
4. Bleeding in fly ash concrete is significantly
reduced and other properties like
cohesiveness, pumping
characteristics and surface finish are improved.
5. As the fly ash content increases there is
reduction in the strength of concrete. This
reduction is more at earlier ages as compared
to later ages. This is expected, as the
secondary hydration due to pozzolanic action is
slower at initial stage for fly ash concrete.
6. Rate of strength development at various
ages is related to the W/Cm and percentages
of fly ash in the concrete mix.

32. 7. Modulus of elasticity of fly ash concrete also
reduces with the increase in fly ash percentage
for a given
W/Cm. Reduction in E value is much lower as
compared to compressive strength.
8. Shrinkage of fly ash
concrete mix is similar to
control concrete mix.
9. Fly ash concrete is more durable as
compare to OPC concrete. Significant
reduction in RCPT values at 56 days and 90
days indicates much lower permeability of fly
ash concrete as compare to OPC concrete.
The time has come for appreciating the fact
without any reservation that fly ashcan be
gain fully used in
Making concrete strong, durable, Eco-friendly and
economical.
FUTURE WORK.............