Cement is a binding material used in construction to construct different structures like buildings, bridges, roads, etc. There are different ingredients and components from which cement is prepared.
Main Component of cement in Percentage
- Lime (Cao) – 62%
- Silica (Slo2) – 22%
- Alumina (Al2o3) – 5%
- Magnesia (MgO) – 2%
- Calcium sulphate (Caso4) – (3-4)%
- Sulphur trioxide (so3) – 1%
- Iron oxide (fe2o3) – 3%
- Alkalies – 1%
Cement Chemistry Notation
Function of Component of Cement
1) Lime:- (62%) (cao)
- Make cement sound & strong.
- If excess, cement unsound & expand.
- If deficient, the strength of the cement decrease.
2) Silica (22%) (Sio2)
- Impact strength to cement due to the formation of dicalcium silicate & tricalcium silicate.
- If excess, increase strength but prolongs its setting time.
3) Alumina (5%) (Al2o3)
- Impacts quick setting quality to cement.
- Lowers the clinker temperature.
- Excess alumina reduces strength.
4) Calcium sulphate (4%) (Caso4), (Gypsum)
Helps in increasing the initial setting time of cement.
5) Iron oxide (3%) (Fe2o3)
- Provide color, hardness & strength
- Help in the fusion of raw materials during the manufacture of cement.
6) Magnesia (2%) (Mgo)
- When present in small amounts, it give strength and hardness.
- When present in excess, it makes cement unsold.
7) Sulphure trioxide (So3) (1%)
- If present in small quantities, it makes a cement sound.
- If present in excess quantity, it makes cement unsound.
8) Alkalies (1%)
- It should be present in small quantities.
- Alkalies in excess will cause efflorescence.
Main ingredient of Cement – Bouge compound
- Tricalcium silicate (C3s) (3cao.sio2) Alite 48%
- Dicalcium silicate (C2s) (2cao sio2) Belite 25%
- Tricalcium aluminate (C3A) (3cao Al2o3) celite 10%
- Tetracalcium Alumina ferrite (C4A1f) (4caoAl2o3fe2o3) felite 10%
Characteristics of different ingredients of Cement
1) C3s
- It helps in the strength of cement before 28 days.
- It is responsible for the rapid hardening of the cement.
2) C2s
- Strength after 28 days
- Low heat cement
- Slow hardening
3) C3A
- Initial setting
- High heat generate
- If in excess amount – crack
4) C4AF
- Strength
- Poor binding property
Function of Bouge compound (Composition of cement Clinker)
1) Tricalcium silicate (3cao.sio2) (c3s) 45% (Alite)
- Generates heat more rapidly.
- Hydrates & hardness rapidly.
- Responsible for initial set & early strength.
- Posses less resistance to chemical attack.
2) Dicalcium silicate (2cao.sio2) (C2s) 25% (Belite)
- Cement hydrates slowly.
- Generate less heat of hydration.
- Hardens more slowly.
- Provider good ultimate strength.
- Offers more resistance to chemical attack.
3) Tricalcium aluminate (3Cao Al2o3) (C3A) (10%) (Celite)
- Cause initial setting of cement.
- React fast, generating large amounts of heat.
- It is the first compound that reacts with water when cement is mixed with water.
4) Tetra calcium alumina ferrite (C4AF) (10%) (Felite)
- Poor cementing value.
- Comparatively inactive.
- Reacts slowly generate a small amount of heat.
- Does not play any significant role in hydration.
Q.1) Name the important raw material used in manufacturing of Cement
Ans:- The important raw materials used in the manufacturing of cement are given below.
- Lime (Cao) – 62%
- Silica (Slo2) – 22%
- Alumina (Al2o3) – 5%
- Magnesia (MgO) – 2%
- Calcium sulphate (Caso4) – (3-4)%
- Sulphur trioxide (so3) – 1%
- Iron oxide (fe2o3) – 3%
- Alkalies – 1%
Q.2) What is the most dominant constituent of cement?
The most dominant constituent of cement is calcium silicates. Calcium silicate is also known as clinkers. They are formed from the heating of a mixture of limestone and clay at high temperatures.
Cement powder contains calcium silicate in more quantity. It helps cement for hardening and provides strength when mixed with water.
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