Effect of Flyash with the lime addition on the durability of concrete.

1. EFFECT OF FLY ASH WITH LIME
ADDITION ON DURABILITY OF
CONCRETE
ADITYA DIVYADARSHI
1311022
CV-05
BY

2. FLY ASH-INTRODUCTION
• Fly ash is a fine powder produced as a product from industrial
plants using pulverized coal or lignite as fuel.
• It is the most widely used pozzolan siliceous or
aluminosiliceous in nature in a finely divided form.
• They are spherical shaped “balls’’ finer than cement particles.

3. FLY ASH AS A SUPPLEMENTARY:
Apart from technical advantages it attributes to the concrete properties,
fly ash has its own benefits
• Problem of disposal:
In India alone, we produce 75 million tons of fly
ash every year, the disposal of which has become a
serious environmental problem. The effective use
of fly ash in concrete making is therefore attracting
serious considerations of concrete technologists
and government departments.

4. Global CO2 emissions:
 Global cement production is about 1.3 billion tons in 1996
and production of every 1 ton of cement emits 0.87 ton of
carbon dioxide.
 In broader terms, 7% of global CO2 emissions can be
attributed to Portland cement industry.

5. FLY ASH IN CONCRETE:
 Fly ash could be an expensive replacement for Portland cement in concrete and
using it, improves strength, segregation and ease of pumping concrete.
Fly Ash particles provide a greater
workability of the powder portion of the
concrete mixture which results in greater
workability of the concrete and a lowering of
water requirement for the same concrete
consistency.
The rate of substitution typically specified is
a minimum of 1 to 1 ½ pounds of fly ash to 1
pound of cement

6. • Class F is fly ash produced from burning anthracite or
bituminous coal, and Class C is produced from the
burning of sub-bituminous coal and lignite.
• Class F is low in lime, under 15 percent, and contains a
greater combination of silica, alumina and iron (greater
than 70 percent) than Class C fly ash.
• Class C fly ash comes from coals which may produce an
ash with higher lime content — generally more than 15
percent often as high as 30 percent. Elevated CaO may
give Class C unique self-hardening characteristics.

7. PHYSICAL PROPERTY OF FLY
ASH

8. PROPERTIES OF FLY ASH

9. CHEMICAL PROPERTY OF FLY ASH

10. The fly ash from boilers where
mechanical collectors
are used is coarser than fly ash from
electrostatic precipitators.
 The color varies from light to dark
grey depending upon its carbon
contents.
 The quality of fly ash varies from
source to source.
 fly ash particles are small, they
effectively fill voids
PHYSICALASPECTS:

11. Though fly ash offers environmental advantages it
also improves the:
 Performance and quality of concrete.
 Fly ash affects the plastic properties of concrete
by improving workability
 Reduces water demand
 Reduces segregation and bleeding.
Lowers heat of hydration.
 Fly ash increases strength
Reduces permeability

12. MECHANICALATTRIBUTES:
The main benefit of fly ash in concrete is that it not only
reduces the amount of non durable calcium hydroxide
(lime), but in the process converts it into calcium silicate
hydrate (CSH), which is the strongest and most durable
portion of the paste in concrete.
REACTION WITH MOISTURE:

13. HEAT OF HYDRATION:
•Fly Ash has a lower heat of hydration.
•Portland Cement produces considerable heat upon hydration.
•In mass concrete placements the excess internal heat may contribute to
cracking.
•The use of Fly Ash may greatly reduce this heat build up and reduce
external cracking.

14. CONCLUSION:
Fly ash thus holds a vast potential for improving the modern day
concrete when it comes to quality in the long term. In spite of
being an industrial waste, it can improve durability and reduce
heat of hydration.
The prospects of fly ash are still being underused even today.
Thus keeping in mind about environmental concerns and its
indispensability as a mineral admixture, the values of fly ash
should be effectively garnered .

15. REFERENCES:
• Concrete technology(theory and practice) –M.S shetty
• Activation of fly ash through
Nanomodification- ACI spring convention Shiho Kawashima, Columbia University
• Enhancing performance of high volume fly ash concrete –ACI spring convention.
• http://www.concretebasics.org/articlesinfo/fa8.php#sthash.r8p7Ivtk.dpuf
• magazine of concrete research- volume 64

16. THANK YOU