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CEMENT

 Cement is the most useful material used in building construction and in other construction works also. It is made of calcined limestone and clay minerals. It consists of various compounds such as lime (60-67)%, silica (17-25)%, alumina (3-8)%, calcium sulphate (3-4)%, iron oxide (3-4)%, magnesia (1-3)%, sulphur (1-3)%, alkali (<1%)


All these different compounds have different varieties. Lime gives soundness, silica gives strength, alumina gives setting time, calcium sulphate increases setting time, iron oxide imparts reddish brown color, magnesia gives yellowish color, sulphur is used for unsound & alkali gives staining and efflorescence respectively. 

Types of Cement:-

1) Rapid Hardening Cement. 

2) Extra Rapid Hardening Cement.

3) Sulphate Resisting Cement.

4) Quick Setting Cement.

5) Low Heat Cement

6) Hydrophobic Cement.

7) High Alumina Cement.

8) Portland Pozzolona Cement.

Portland Cement was discovered by Joseph Aspdin in 1824. He named it portland after portland stoned which is of same color and becomes hard as that of stone after drying. For more about portland cement you can visit here. 

There also various types of tests that are done on cement. The following tests are :- 

1) Fineness test:- This is done with 90 micron sieve where the retaining of cement should not be more than 10%.

2) Consistency test:- This is done with the help of Vicat's needle apparatus where a 12mm plunger is allowed to fall on the cement paste to see its consistency. With this help of Vicat's apparatus setting time of cement is also tested. It consists of two needle's one is used for to check it's initial setting time while the other one is used for final setting time.

3) Soundness test:- This is done with the help of Le-Chatellier's apparatus to check it's unsound. Unsound means increase the volume of cement. And it is due to the presence of excess lime or magnesia. 

4) Compressive Strength test:- This type of test is done in a cube mould of size 70.7mm cubes. It is mixed with a cement mortar of ratio of 1:3 and then the cubes are de-moulded after 24 hours. And after that the tests are taken at 3, 7 and 28 days in compression testing machine.

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Location: Duliajan, Assam, India

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