What is Concrete?
Concrete is the mixture of cement, sand, aggregates and water. Cement concrete is the major building material in the construction industry. It can be easily moulded into durable structural members.
In concrete sand is used as fine aggregates, gravels and crushed stones are used as coarse aggregates. The cement acts as a binding material which forms a paste with water and on hardening, this cement paste holds coarse and fine aggregates together to form a solid mass.
Properties of Concrete
The cement concrete possesses the following properties:
- The thermal expansion of concrete is approximately 0.4 mm per meter.
- Concrete shrinks as it dries and expands again on wetting and extent of movement depends upon the modulus of elasticity of the cement.
- It binds rapidly with steel and as it is weak in tension, the steel reinforcement is placed in concrete at suitable places.
- It tends to be porous.
- It has a high degree of abrasion resistance.
- It has a high degree of electrical resistance.
- It is more economical than steel.
- It has high compressive strength.
- It is free from corrosion so as it has no effects of atmospheric agents on it.
- It hardens with time and process of hardening is continue to a long time and after a long time, it attains the sufficient strength.
- It should be remembered that apart from other materials, the concrete comes to the site in the forms of raw materials only. Its final strength and quality depend entirely on local conditions and the person handling it. However, the materials of which concrete is composed may be subjected to rigid specifications.
Uses of Concrete
- Concrete is extensively used in the construction of various structures such as Building, Bridges, Dams and all other Civil Engineering structure.
- Concrete is used for the construction of various architectural compositions such as vaults, dams, shells, bridges etc.
- Concrete is also used in prestressed construction.
Advantages of Concrete
- The monolithic character of concrete gives the rigidity and appearance to the structure.
- It can be used for various purposes at various climate conditions such as for the construction of walls, foundation, roads, runway, pavement, water retaining structure etc.
- It is much economical than steel.
- It has much compressive strength.
- The maintenance cost of concrete is practically nil.
- It may also be used as a soundproofing material.
- It is durable and liable to decay easily.
- It can be used for the purpose of the lining of tunnels.
- It acts as a waterproofing material.
- Concrete can be easily handled and moulded into any desired shape.
- The ingredients used for concrete are locally available.
- Its surface is capable of resisting abrasion.
- It can even be sprayed on and filled into fine cracks for repairs by the guniting process.
- It can be pumped and hence it can be laid in difficult positions also.
Disadvantages of Concrete
- It is required to provide expansion joints in case of long structures.
- It is required to provide contraction joints to avoid drying shrinkage.
- These structures are heavy in weight and subjected to heavy creep.
- It requires more time for curing to develop strength.
- These have low tensile strength.
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