In this article we will discuss about:- 1. Evaluation of Aluminium as Building Material 2. Economics of Using Aluminium 3. Forms 4. Uses 5. Conclusion.
Evaluation of Aluminium as Building Material:
The building industry occupies a very important place in the national economy in terms of capital input and employment potential. The industry is dominated by materials like brick, cement, steel and to a certain extent by plastics and glass.
Following characteristics of aluminium have contributed for the establishment of aluminium as an important building material in the economically advanced countries:
(1) Air Tightness:
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A well designed aluminium door, window, etc. is perfectly airtight and sealed for dust and rain water, when closed. This is a very high functional advantage in a modern fully air-conditioned building.
(2) Appearance:
The finished aluminium is generally smooth, having bright finish which is highly amenable to further finishing as demanded by the application. Depending on the type of building and decorative style or scheme, the shades of various colours can be selected.
(3) Crygonics:
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The science dealing with the effects of very low temperatures on the properties of matters is known as the crygonics. The aluminium is highly suitable for sub-zero temperatures. Any structural steel used at sub-zero temperatures will become extremely brittle and give way. It is this characteristic of aluminium which has been considered for its use in prestigious snow-borne structures of Antarctica III and IV expeditions.
(4) Ease in Fabrication and Assembly:
As aluminium is comparatively soft and ductile metal, the fabrication of doors, windows, etc. can be easily carried out. The aluminium alloys can be cast, forged, extruded, rolled and welded with relative ease compared to any other metal. The aluminium corrugated sheets do not break or crack during or after erection because aluminium is not brittle. An aluminium structure can easily be dismantled, transported and re-erected in different locations.
(5) Handling and Transport Cost:
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As aluminium is very light, the cost of its handling and transport is very low and this is quite an important factor in material transportation to remote hilly areas and difficult terrains.
(6) High Corrosion Resistance:
The aluminium has excellent corrosion resistance and it can resist weathering conditions very well. It can also very well withstand humid and hot dry conditions. The life of a properly designed aluminium frame may be the same as that of the building itself. On account of its excellent corrosion resistant property, the aluminium corrugated sheets are ideal for use in power plants, steel plants, chemical plants, paper mills, saw mills, fertilizer plants, tanneries, rayon plants, petroleum refineries, etc.
(7) High Reflectivity:
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As aluminium possesses very good reflectivity, it does not absorb radiant heat and low absorption heat helps in maintaining the surrounding area cool during summer and warm in winter.
(8) High Scrap Value:
The scrap value of aluminium is very high and as it hardly deteriorates, it enjoys a high resale value.
(9) High Strength to Weight Ratio:
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As aluminium possesses very high strength to weight ratio, the overall weight of the building is considerably reduced. Such a reduction of weight will also help in achieving speed in construction and in the decrease of load on the foundation of building.
(10) Maintenance Cost:
Due to high corrosion resistance of aluminium, the maintenance cost is negligible and properly treated aluminium sections can withstand both sea-coast and industrial atmosphere for more than 25 to 30 years without any maintenance.
(11) Noise Control:
The aluminium is an excellent reflector of electro-magnetic and sound waves. An aluminium building is therefore less affected by external noises as compared to buildings made from other materials.
Economics of Using Aluminium:
The aluminium is definitely an expensive material in the initial cost. But it proves to be economical in long run because of the benefits derived from its properties such as durability, virtual elimination of maintenance, lightness in weight, etc.
The advantages claimed by using aluminium in respect of the following items are briefly mentioned:
(1) Asbestos Cement Corrugated Sheets:
These sheets are cheaper than aluminium corrugated sheets. But they are about 7 times heavier than aluminium sheets and hence they require heavy structural support. The asbestos being a fragile material is liable to breakages and as it is reported to pose a serious health hazard, it has been banned in several industrialised countries.
(2) Corrugated Galvanized Iron Sheets:
These sheets are costly as compared to the aluminium corrugated sheets. Moreover, being lighter in weight, the aluminium corrugated sheets require light structural supports and they offer ease of erection at any height.
(3) Steel:
In case of steel, there are only limited standard structural sections like I, channel angle and Tee which a designer can adopt. The aluminium offers limitless possibilities of different shapes and profiles. The designer enjoys full freedom in the matter of designing of a profile in such a way that the metal is distributed exactly where it is needed for structural requirements, weather proofing and mechanical needs.
In case of aluminium, the infinite number of shapes and sections can be produced by the extrusion process in continuous lengths.
(4) Timber:
As compared to timber, the initial cost of aluminium is less and with practically zero maintenance cost, the aluminium is superior to timber which requires periodical painting. The replacement of timber by aluminium is also of vital importance from the view point of preserving the forest wealth of our country.
Forms of Aluminium:
The aluminium as used in the building industry usually takes one of the following four forms:
(1) Casting based
(2) Extrusion based
(3) Foil and powder based
(4) Sheet based.
(1) Casting Based:
The known applications of this form are as follows:
(i) Baluster-Head:
The cast aluminium baluster-heads add elegance to the interior of buildings and complicated figures can be developed.
(ii) Hardware and Fittings:
The unconventional designs of hardware and fittings can be produced in casting process.
(iii) Security and Decorative Grills:
This application has tremendous potential in our country.
(2) Extrusion Based:
The known applications of this form are as follows:
(i) Door and Window Frames:
This is the major application of aluminium in buildings. It is possible to make several types of windows to suit the functional requirements like side hung and fixed, side hung open-able, sliding, top hung, etc.
(ii) Fascia Panels and Curtain Walls:
A curtain wall is an external non-load bearing wall mainly designed to carry its own weight and at the same time, it is sufficiently strong to resist wind loads in accordance with the normal building regulations.
The larger aluminium fascia panels and curtain walls can be produced by using interlocking aluminium extrusion.
(iii) Geodesic Domes and Space Grids:
A geodesic dome is a vaulted structure of light weight straight elements that form interlocking polygons. With aluminium as the structural material, such architectural marvels have been built.
(iv) Green Houses and Roof Top Gardens:
For cold climate, the aluminium extrusions are used to provide green houses and roof top gardens.
(v) Hardware and Fittings:
The aluminium is extruded in the form of hardware items like handles, tower bolts, aldrops, curtain rails, etc.
(vi) North Light Glazing Frames:
For industrial sheds, the aluminium frames for the north light glazing provides an easy and quick way to erection and a maintenance-free installation.
(vii) Partitions and Space Dividers:
The aluminium structural framework is ideally suitable for office interiors where high finishing quality is essential.
(3) Foil and Powder Based:
The known applications of this form are as follows:
(i) Decorative Laminate:
The printed decorative laminates are extensively used as wall papers, partition panels, etc.
(ii) Insulative Foils:
These can be conveniently used for insulating air-conditioning ducts in large central air-conditioned systems.
(iii) Paints:
The aluminium powder based paints are useful to grant protection to the buildings against corrosive environment.
(iv) Water-Proofing Sheet:
The foil based laminates provide a maintenance-free barrier for protection of roof against water leakage.
(4) Sheet Based:
The known applications of this form are as follows:
(i) Cable Tray:
The aluminium is fast replacing the galvanized iron trays for carrying insulated electric cables in industrial complexes particularly in chemical industries.
(ii) Planar or Flat Type False Ceilings:
The use of such type of false ceilings exhibit supreme aesthetic appearance.
(iii) Prefabricated Houses:
The use of prefabricated houses can be made for colder and tropical climates. It can be sandwiched with polyurethane to form a better material for this type of application. It can also prove to be an effective panelling material for mobile houses and caravans.
(iv) Rain Water Articles:
The non-corrosive aluminium is a natural choice for the gutter, spouts, etc. for the disposal of rain water.
(v) Ridging and Angles of Roof:
The aluminium can be used for all building requirements of corner flashings, ridgings, monitor roofs and gable-end flashings.
(vi) Roofing and Siding:
The aluminium is an ideal material for roofing and siding of industrial buildings, workshops and sheds.
Uses of Aluminium:
This metal is chiefly used for making parts of aeroplane, cooking utensils, electric wires, window frames, glazing bars, corrugated sheets, structural members, foils, posts, panels, balustrades, bathroom fittings, precision surveying instruments, furniture, etc.
Its other uses can be mentioned as follows:
(i) It is used as a reducing agent in the manufacture of steel.
(ii) It is used for making aluminium alloys, automobile bodies, engine parts and surgical instruments.
(iii) It is used in the casting of steel.
(iv) It is used in the manufacture of electrical conductors.
(v) It is used in the manufacture of paints in powder form.
Conclusion:
It is thus seen that aluminium is receiving more attention and significance as a building material. The average per capita consumption of aluminium in the world is 40 N and for our country, it is only about 4 N. In contrast, our country has one of the largest and richest bauxite reserve, about 12.5% of the world reserve. Our country contributes only 1.4% of the world aluminium production.
The reasons for such a situation can be enumerated as follows:
(i) Nearly 50% of the available metal is used for the electrical industry leaving the balance 50% to be shared by the other industries such as buildings, transport, utensils, etc.
(ii) The aluminium smelting capacity has always lagged behind the demand for the metal.
(iii) The chronic power shortage has further curbed the capacity utilization of the smelters.
(iv) The high excise and other tariffs make the metal very expensive to the end-user.
The aluminium is not strange or unfamiliar to us and it can be safely predicted that the application of aluminium is poised for a take-off especially with the importance and emphasis it is getting in the building and construction industry.