SAMARTH ENGINEERING COLLEGE,

HIMATNAGAR

PROJECT :- APPLICATION OF FLYASH FOR PARTIAL REPLACEMENT OF CEMENT IN CONCRETE

RATHOD PRITESH V. (100880106039)PATEL AKASH K . (100880106013)

PATEL VISHAL R. (100880106010)

INTRODUCTION OF FLY ASH Fly ash is one of the residues generated in combustion, and

comprises the fine particles that rise with the flue gases. Ash

which does not rise is termed bottom ash. In an industrial

context, fly ash usually refers to ash produced during

combustion of coal.

Fly Ash Concrete

In the recent time, the importance and use of fly ash in

concrete has grown so much that it has almost become a

common ingredient in concrete, particularly for making

high strength and high performance concrete.

In India alone, we produce about 75 million tons of fly ash

per year, the disposal of which has become a serious

environmental problem.

Fly Ash Concrete

It was estimated that global production of cement is about

1.3 billion tons in 1996. Production of every tone of

cement emits carbon dioxide to the tune of about 0.87 ton.

Expressing it in another way, it can be said that 7% of the

worlds carbon dioxide emission is attributable to Portland

cement industry.

Amount of Fly Ash Generated in India:

The fly ash generation is increasing in such a proportion that it

will not be possible for the cement industry alone to utilize the

same. New avenues of gainful utilization of fly ash have to be

found and promoted.

Plan Period Terminal Area

Power Generation

(MW)

Coal

(million tons)

Fly Ash

(million tons)

8th

plan 1996-97 50,000 210 80

9th

plan 2001-02 87,000 285 110

11th

plan 2006-07 1,16,400 400 140

11th

plan 2009-10 1,38,300 500 175

12th

plan 2011-12 1,68,500 680 210

13th

plan 2012-2013 1,98,700 826250

CHARACTERSTICS OF FLY ASH

There are two type characteristics of fly ash

1. Physical characteristics of fly ash.

2. Chemical characteristics of fly ash

TYPES OF FLY ASH I) Class F

II) Class C

Class F Type Fly ash normally produced by burning anthracite or

bituminous coal, usually has less than 5% CaO. Class F

fly ash has pozzolanic properties only.

In other word, 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 20%

lime (CaO).

Class C Type Fly ash normally produced by burning lignite or sub-

bituminous coal. Some class C fly ash may have Ca O

content in excess of 10%. In addition to pozzolanic

properties, class Cfly ash also possesses cementitious

properties.

Class C fly ash generally contains more than 20% lime

(Ca O). Alkali and sulfate (SO4) contents are generally

higher in Class C fly ashes.

Advantages of fly ash in concrete:- Reduced water content for a given workability or

improved workability at the same water content.

The rate of bleeding is reduced while workability is

increased.

Improved long term strength and durability performance.

Lower shrinkage and porosity as a result of the lower

water content.

Lower permeability and better resistance to sulphate

attack.

Disadvantages of fly ash in concrete:-

Concrete changes from a liquid to a solid a few hours after

pouring, but the curing process may take much longer.

Fly ash admixtures can lengthen the time it takes for

concrete to set.

Fly ash reduces the amount of air entrainment, and

concrete mixtures high in fly ash often require more air-

entraining admixture.

It is more difficult to control the colour of concrete

containing fly ash than mixtures with Portland cement

only.

Uses of fly ash CONCRTE

Mass concrete section

Ready mix and precast application.

Marine environment concretes

For use with alkali-reactive aggregates

Water retaining structure

Self compacting concrete

Tunnelling concretes

Road stabilization

Pumped concrete

EXPERIMENTAL PROGRAMS

Experiment work is carried out to study mechanical

properties of normal concrete and concrete with Fly Ash

like compressive strength and workability of concrete. Fly

Ash are used for study purpose by varying percentage of

fly ash as 5%, 10%, 15%, 30 and 45 % of weight of

cement.

FLY CONCRE TEST

1. Slump test.

2. Compression test.

Slum Test To determine the workability of concrete mixes of given

proportion by SLUMP TEST.

Prepare four concrete mixes with varying water cement

ratio say 0.50.Use 2.5 Kg of cement,5 Kg of fine

aggregate and 10 Kg of coarse aggregate for each

mix(1:1.5:3 ratio).The ingredients be first mixed dry

thoroughly before adding water.

Fill the freshly mixed concrete in a clean slump cone in 4

successive layers, tamping each layer properly (25 times)

before adding another.

Slum Test

Compressive Test To determine the compressive strength of fly ash concrete

(concrete M20)

The determination of compressive strength of concrete is

very important because the compressive strength is

criterion of its quality.

The strength is expressed in N/mm2.

The concrete specimens are generally tested at ages of 7

days, 14 days and 28 days

Compressive Test

compressive strength Testing

compressive strength observation table for 28 day

% OF FLY ASH COMPRESSION % DIFFERENT

STRENGTH W.R.T. NORMAL

CONCRETE

0 23.28 0

5 26.96 9.24

10 28.40 15.07

15 20.30 -17.75

30 12.20 50.57

45 9.44. 61.75

CONCLUSIONWorkability in terms of slump value

Decease with increase in % replacement of fly ash

At 5% replacement concrete is having medium

workability

At 10% replacement concrete is having low workability

At 15% replacement concrete is having very low

workability

CONCLUSION Cube compression test

Decease with increase in % replacement of fly ash

9.24% increase at 5% replacement at 28 days

15.07% increase at 10% replacement at 28 days

So, from the observed test results, replacement of cement

by fly ash in concrete is practically possible up to 10%

only. If 15% or more replacement is required, plasticizers

should be used to have required workability.