Cement And Type of Cements

 

CEMENT

Cement:-  Cement is an extremely finely ground product obtained by burning the specified amount of calcareous and argillaceous raw materials.

TYPES OF CEMENT

1. Ordinary Portland Cement (OPC)

2. Rapid Hardening Cement (RHC)

3. High Alumina Cement

4. Portland Pozzuollana Cement

5. Blast Furnase Slag Cement

6. Super Sulphated Cement

7. Low Heat Cement

8. Air Entraining Cement

9. Quick Setting Time

10. Coloured Cement

11. White Cement

12. Acid Resistant Cement

13. Hydrophobic Cement

S. No	Ingredients	Approximate %age	Range
1.	Lime	60-65	64
2.	Silica	17-25	22
3.	Alumina	4-8	6
4.	Iron oxide	1-6	3
5.	Magnesia	1-3	2
6.	Calcium sulphate	3-5	3.5

There are three types of grade of cement.

1)      Grade 33

2)      Grade 43

3)      Grade 53 

Grade 33 means that after 28 days, the cement of cement is 33N/mm² .

The ratio of cement mortar must be 1:3.

PROPERTIES OF CEMENT:-

The properties of cement entirely depends upon its composition, burning and grinding. The important properties of a good cement are:-

1)      Strength: The compressive strength of cubical blocks of ordinary Portland Cement and sand (1:3) after 7 days should not be less then 175 kg/cm² and tensile strength should not be less then 21 kg/cm² .

2)      Fineness : The quality of cement depends upon its fineness property. So a good cement should be fine. The fineness of cement may be determined by sieve test. Also by touching the cement, it may be checked and should be smooth.

3)      Soundness : A good quality cement should not undergo large change in volume after setting. Also it should not crack or disintegrate after setting.

4)      Presence of Lumps : By absorbing the moisture from atmosphere the lumps are formed. A good cement should be free from lumps. These can be avoided by storing the cement away from damp places.

5)      Colour : The colour of cement should be greenish grey. The colour indicates the degree of burning. e.g a yellowish colour indicates poor burning.

6)      Resistance to moisture : The good cement should resist against moisture.

7)      Plasticity :  Any Cement should be plastic in nature.