16-01-2013, 01:19 PM
ALTERNATE CONSTRUCTION MATERIAL
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INTRODUCTION
Housing has been continues to be of prime concern to human beings. This problem has become more acute in the developing countries as their rate of growth of population is far in excess of rate of new dwellings being added.Shelter has been, is and will always remain an important basic need of human beings next only to food.Hence it should be designed and constructed as a permanent structure and it should be capable of being used for longer periods with low maintenance and replacement often become a problem because of the non availability of technical personnel or technology.
In this regard the modern trend should aim at achieving the desired character at the minimum cost.Construction industry is the largest industry in our country contributing to more than 40% of total industrial activities.It has been found that the cost of construction of buildings for an ordinary person is becoming unaffordable.However many investigations are going on with varied degree of success, as a building cost mainly depends on the raw materials like stone, aggregate, sand, cement, steel and bricks.
Here the reports on methods to reduce the cost of construction materials and techniques, which forms the major part of the constructional cost, have been studied and a brief report is presented.
FLY ASH AS REPLACEMENT FOR CEMENT IN CONCRETE
Fly ash is a material collected from the flue gases of coal burning using electrostatic or mechanical precipitators.
By-product of combustion of pulverized coal in chemical plant.
Finer than Portland cement.
Consists of small glassy ranging from less than 1 micron to 100 microns.
Components are silica (SiO2), alumina (Al2O3) and oxides of calcium and iron (CIO, Fe2o3).
Used in many other applications in civil engineering construction and other special materials.
Utilization of coal combustion by products as to disposal
Cost of disposal of waste is reduced.
The area used for disposal is reduced.
Coal ash sales can fetch financial returns.
Use of a coal ash can replace some expensive natural resources.
Conservation of non-renewable energy.
Fly ash as puzzling in concrete:-
If fly ash is added to concrete, the calcium hydroxide liberated.
During hydration cement slowly reacts with amorphorous reaction products.
Time dependent imparting additional strength to concrete