FLY ASH – WEALTH OR WASTE

FLY ASH

Fly ash, a principal byproduct of coal burning power plants, is an industrial waste product containing large amounts of silica, alumina and small amount of unburned carbon, which pollutes environment.

This fly ash has real disposal problems, and should hence be utilized effectively for various purposes.

Fly ash, being primarily pozzolanic, can actually replace a

percentage of the Portland cement, to produce a stronger, more

durable and more environment friendly concrete.

The cement production process releases a lot of carbon-di-

oxide in atmosphere, which is the primary green house gas that

causes global warming.

Hence replacement of a considerable portion of cement by fly

ash, can make a major contribution toward solving the global

warming problem.

ASH PRODUCTION IN INDIAYEAR ASH PRODUCED IN MILLION

TONESASH USED IN MILLION TONES

2006-07 116 24.80

2007-08 123 27.15

2008-09 130 29.68

2009-10 138 32.21

2010-11 145 34.74

2011-12 154 38.00

2012-13 163 42.50

PROJECTED VALUE OF FLY ASH UTILISATION

2013-14 173 48.00

ASH WITH PORTLAND CEMENT CONCRETE

Fly ash can be used with Portland Cement Concrete as a cement extender to enhance the performance of the concrete. Some of the resulting benefits are:

• Higher Ultimate Strength• Increased Durability, • Improved Workability• Reduced Bleeding• Increased Resistance To Sulfate Attack • Reduced Shrinkage

FLY ASH BRICKS

Fly ash possesses both ceramic as well as pozollanic properties and therefore can be utilized in a unique way for manufacturing bricks.

This proves to be very useful for building construction. These bricks produced by the new process are superior in

quality as they offer higher cold crushing strength and smooth, uniform size.

S.NO FEATURES NORMAL CLAY BRICKS

FLY ASH BRICKS

1 BINDING LIGHT DENSE

2 COLOUR VARY UNIFORM

3 SHAPE IRREGULAR UNIFORM

4 WEIGHT MORE LESS

5 COMPRESSIVE STRENGTH

35 KGS/SQ.CM 100 KGS/SQ.CM

6 WATER ABSORPTION

20-25% 6-12%

ECONOMIC SAVINGS:Reduces excavation of clay.Low cost of brick as compared to clay brick as same

quality.Number of bricks required per unit volume of construction

is less.Less consumption of mortar.Less number of joints in case of blocks.Plastering is not required if it required

FLY ASH FOR ROAD

Fly ash can be used for construction of road and embankment. This utilization has many advantages over conventional methods. • Saves top soil which otherwise is conventionally used .•Avoids creation of low lying areas (by excavation of soil to be

used for construction of embankments) .•Avoids recurring expenditure on excavation of soil from one place

for construction and filling up of low lying areas thus created

•Does not deprive the nation of the agricultural produce that would be grown on the top soil which otherwise would have been used for embankment construction. • Reduces the demand of land for disposal/deposition of fly ash

that otherwise would not have been used for construction of embankment. Good Compaction .• Free draining ( Less interruption due to raining ).• Light in weight ( can be used in weak sub – grade )

The superior benefits of PFA as a fill material come from its lower density when compared to soils. PFA has a density of 1.5Mg/m3 compared to around 2Mg/m3 for soils.

The benefits of PFA as a fill material include:

•Reduced settlement in poor underlying soils. •Lightweight and therefore leads to savings in materials and

haulage costs. For example, there is approximately a 25% reduction in lorry movements

FLY ASH AS FILL MATERIAL

• Increased stability as its self-supporting properties provide stable conditions for shallow trenches and other excavations • Immediate and increasing strength. For example, field tests on

existing embankments have demonstrated the positive strength gain and long-term stability of PFA. In addition, PFA will absorb water and therefore is not easily saturated, allowing construction work to continue in bad weather conditions •No internal settlement

SOIL STABILIZATION• Soil stabilization is the alteration of soil properties to improve

the engineering performance of soils. •Modification of soil properties is the temporary enhancement

of subgrade stability to expedite construction.• Stabilization can increase the shear strength of a soil and/or

control the shrink-swell properties of a soil, thus improving the load-bearing capacity of a sub-grade to support pavements and foundations. • Stabilization can be used to treat a wide range of sub-grade

materials from expansive clays to granular materials.

CONCLUSION

Let Us Harness A Billion Dollar Resource That Has Been Wasted

So Far