Cement - the very essential material for construction

In good olden days,  buildings were constructed using mud, stones, bricks or wooden scantlings, tin sheets etc. The binding material was usually of mud and lime mixture. In ancient Rome and Greece, it is reported that about 2000 years ago lime and volcanic ash was mixed with water  and then used for jointing the blocks. However the credit for the modern cement goes to Joseph Aspidin of England who developed what is known as Portland cement. In 1824 he took a patent for the same. In 20^th century, the manufacture of cement spread over the whole world.

Manufacture of cement

There are four stages in the manufacture of cement.

1.    Crushing and grinding the raw material,(mixture of lime and clay)

2.    Blending the same in correct proportions

3.    Burning them in a kiln at very high temperature

4.    Grinding the burnt product (clinker) after adding gypsum

There are three processes of manufacture of cement. They are

1.    Wet 2. Dry 3. Semi dry

Side effects of manufacture of cement

About 4% to 8% of carbon dioxide emission in the world comes from manufacture of cement. This in turn leads to increased  global warming.

Manufacture of cement in India

1904 South India  Industries Ltd  Madras

1914 Indian Cement Company Ltd, Porbunder, Gujarat

Tests on cement

For the quality control of cement, various tests are conducted in the laboratory. They are:

-Strength, setting time, fineness, consistency, soundness, chemical composition

Different types of cement

Ordinary Portland cement 33 grade, ordinary Portland cement 43 grade, ordinary Portland cement 53 grade, Portland slag cement, Colored cement: white, Portland pozzolana cement, Hydrophobic Portland cement

                                                              An old house                                     A modern house

   Cement manufacturing plants in India

There are 210 large cement manufacturing plants in India, out of which 77 are situated in Andhra Pradesh, Rajasthan and Tamil Nadu.

Use of cement

Cement is mainly used as a binder in concrete. There are mainly two types of concrete - ordinary concrete and reinforced cement concrete. This is mainly used in  construction of buildings, roads, railways, seaports, airports, dams  etc.

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