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  • It is a naturally available metal in the form of ores which contain small amount of iron and sulphur.
    After removing impurities, it is processed electrolytically to get purest metal. This metal is almost indestructible. Copper scrap can be processed to get original copper.

    Properties of Copper
    1. It is having reddish brown colour.
    2. Its structure is crystalline.
    3. It is highly ductile and malleable.
    4. It resists corrossion.
    5. It can be welded easily at red heat condition.
    6. Dents on the copper can be hammered out.
    7. It has high electric and thermal conductivity.
    8. Its melting point is at 1083¬įC.

    Uses of Copper
    1. It is used as electric wire and cable.
    2. It is used as lighting conductor.
    3. For water proofing the construction joints copper plates are used.
    4. Copper tubes are used for hot and cold water supply, gas and sanitation connections.
    5. It forms a major constituent of brass and bronze.

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  • The term ferro-cement implies the combination of ferrous product with cement. Generally this¬†combination is in the form of steel wires meshes embedded in a portland cement mortar. Wire mesh is¬†usually of 0.8 to 1.00 m diameter steel wires at 5 mm to 50 mm spacing and the cement mortar is of¬†cement sand ratio of 1:2 or 1:3. 6 mm diameter bars are also used at large spacing, preferably in the
    corners. Sand may be replaced by baby jelly. The water cement ratio used is between 0.4 to 0.45.

    Ferro-cement reinforcement is assembled into its final desired shape and plastered directly. There is no need for form work. Minimum two layers of reinforcing steel meshes are required. According to American Concrete Institute “Ferro cement is a thin walled reinforced concrete construction where
    usually a hydraulic cement is reinforced with layers of continuous and relatively small diameter mesh.¬†The mesh used may be metallic or any other suitable material.‚ÄĚ

    Ferro-cement is fast emerging as an alternate material for timber. The history of ferro-cement goes back to 1843 (even before RCC). Joseph Louis Lambet constructed several rowing boats, plant plots and garden seats using ferro-cement. In early 1940’s noted Italian engineer and architect Pier
    Luigi Nervi carried out scientific tests on ferro-cement and used it to replace wood wherever possible.

    He built small tonnage vessels, the largest being 165 tons motor sailor. Nervi also pioneered the architectural use of ferro-cement in buildings. Ferro-cement can be given the finish of teak wood, rose wood etc. and even for making tables, chairs and benches it can be used.

    Properties of Ferro-cement

    1. Its strength per unit mass is high.
    2. It has the capacity to resist shock laod.
    3. It can be given attractive finish like that of teak and rose wood.
    4. Ferro cement elements can be constructed without using form work.
    5. It is impervious.

    Uses of Ferro-cement

    It can be used for making:
    1. Partition walls
    2. Window frames, chejjas and drops
    3. Shelf of cupboards
    4. Door and window shutters
    5. Domestic water tanks
    6. Precast roof elements
    7. Reapers and raffers required for supporting roof tiles.
    8. Pipes
    9. Silos
    10. Furnitures
    11. Manhole covers
    12. Boats.

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  • It is a light weight concrete produced by introducing large voids in the concrete or mortar. Its density¬†varies from 3 kN/m3 to 8 kN/m3 whereas plain concrete density is 24 kN/m3. It is also known as aerated,¬†foamed or gas concrete.

    Properties of cellular concrete

    It has the following properties:
    1. It has low weight.
    2. It has good fire resistance.
    3. It has good thermal insulation property.
    4. Thermal expansion is negligible.
    5. Freezing and thawing problems are absent.
    6. Sound absorption is good.
    7. It has less tendency to spall

    Uses of Cellular Concrete

    1. It is used for the construction of partition walls.
    2. It is used for partitions for heat insulation purposes.
    3. It is used for the construction of hollow filled floors.

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  • Plain concrete possesses deficiencies like low tensile strength, limited ductility and low resistance to¬†cracking. The cracks develop even before loading. After loading micro cracks widen and propagate,¬†exposing concrete to atmospheric actions. If closely spaced and uniformly dispered fibres are provided¬†while mixing concrete, cracks are arrested and static and dynamic properties are improved. Fibre¬†reinforced concrete can be defined as a composite material of concrete or mortar with discontinuous¬†and uniformly distributed fibres. Commonly used fibres are of steel, nylon, asbestos, coir, glass, carbon¬†and polypropylene. The length to lateral dimension of fibres range from 30 to 150. The diameter of¬†fibres vary from 0.25 to 0.75 mm.

    Fibre reinforced concrete is having better tensile strength, ductility and resistance to cracking.

    Uses of FRC

    1. For wearing coat of air fields, roads and refractory linings.
    2. For manufacturing precast products like pipes, stairs, wall panels, manhole covers and boats.
    3. Glass fibre reinforced concrete is used for manufacturing doors and window frames, park benches, bus shelters etc.
    4. Carbon FRC is suitable for structures like cladding and shells.
    5. Asbestos FRC sheets are commonly used as roofing materials.

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  • Strength of concrete in tension is very low and hence it is ignored in R.C.C. design. Concrete in tension¬†is acting as a cover to steel and helping to keep steel at desired distance. Thus in R.C.C. lot of concrete ¬†is not properly utilized. Prestressing the concrete is one of the method of utilizing entire concrete. The¬†principle of prestressed concrete is to introduce calculated compressive stresses in the zones wherever¬†tensile stresses are expected in the concrete structural elements. When such structural element is used¬†stresses developed due to loading has to first nullify these compressive stresses before introducing¬†tensile stress in concrete. Thus in prestressed concrete entire concrete is utilized to resist the load.

    Another important advantage of PSC is hair cracks are avoided in the concrete and hence durability is high. The fatigue strength of PSC is also more. The deflections of PSC beam is much less and hence can be used for longer spans also.

    PSC is commonly used in the construction of bridges, large column free slabs and roofs. PSC sleepers and electric piles are commonly used.

    The material used in PSC is high tensile steel and high strength steel. The tensioning of wires may be by pretensioning or by post tensioning. Pretensioning consists in stretching the wires before concreting and then releasing the wires. In case of post tensioning, the ducts are made in concrete elements. After concrete of hardens, prestressing wires are passed through ducts. After stretching wires, they are anchored to concrete elements by special anchors.

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