↘Article of Concrete

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My assignment 1 - Article of Concrete

Topic:

The Benefits & Drawbacks Of Using Concrete In This World~

Concrete is the most widely used engineering material in this world. It is everywhere in our life such as in buildings, roads, dams and so on. It is also used to make pavements, pipe, architectural structures, foundations,  motorways or roads,  bridges or overpasses, parking structures, brick or block walls and footings for gates, fences and poles. (Wikipedia)

Concrete has been used for construction in various of ancient building. Its history can be traced to ancient Egypt and Rome. Egyptian pyramids has prove that concrete may have been used in their construction works in thousands of years ago. Many of the Roman structures has widespread use of the concrete and it has ensured that many of the buildings can survive until today. For example, the Baths of Caracalla in Rome.

Concrete is a composite construction material of cement, water, aggregate and admixture. Cement is the chemically active constituent but its reactivity is only brought into effect on mixing with water, where a chemical reaction (hydration) will take place. With time, this will become a very hard and strong binding medium for the aggregate particles. The aggregate plays no part in chemical reactions but its usefulness arises because it is an economical filler material with good resistance to volume changes which take place within the concrete after mixing, and its improves the durability of the concrete. (N.Jackson, 1988) Admixture is an additional material that sometimes added to modify certain of its properties.

Concrete is a very durable material. This can be seen by the ancient building of Roman. By the way, to achieve this durability, the correct selection of materials, good design and strict quality control when mixing, placing and curing the concrete is essential. The durability of concrete can let the building stay at rest for several of years. When the concrete has higher durability, it has higher compressive strength. This will be able the building to support higher loading by its compressive strength. So that, it can last very long time without collapse. Besides that, concrete has higher fire resistance. Of all the materials of construction used in a building, concrete is probably the least affected by the fire and is often used to protect load-bearing steel beams from high temperatures. (M.S.J. Gani,1997) In addition, concrete has lower thermal insulator, but it is still able to store lots of heat.

However, there are some drawbacks and limitations of using concrete. One of the drawbacks is the concrete is easy to get the chemical attack such as sulfate attack. Sulfate attack is the process that will decrease the durability of concrete by buildup of internal stressed and breakdown of structure. When the structure is cracking, the concrete is damaging. While, Pozzolanas is used to resistance the sulfate attack. Next, concrete is also weak to physical attack. Due to the buildup of stress from restraint, there will be a cracking of concrete. During the high temperature condition, the concrete will get damage in the form of spalling. Although that concrete has high compressive strength, but at the same time it has lower tensile strength.  The elasticity of concrete is relatively constant at low stress levels but starts decreasing at higher stress levels as matrix cracking develops. Concrete has a very low coefficient of thermal expansion and shrinks as it matures. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete that is subjected to long-duration forces is prone to creep.(Wikipedia)

In my conclusion, concrete brings a lot of benefits to the construction works. It is also a good construction materials for us. But at the same time, there are also some limitations of using concrete. Once we know the correct ways of using it, we can reduce its drawbacks which some are harmful to us.

           

References

þ  N.Jackson, R.K.Dhir (1988), Civil Engineering Materials 4^th Edition, Macmillan Education Ltd, London.

þ  M.S.J. Gani (1997), Cement And Concrete, Chapman & Hall,London,UK.

þ  http://en.wikipedia.org/wiki/Concrete