- Two types of raw materials used in cement manufacturing.
Argillaceous | Calcareous |
Blast Furnace slag | Lime stone |
Cement Rock | Chalk |
Marl | Marine Shells |
Shale and clay |
Chemical Composition of Raw materials:-
Civil wala bhi trick:-
Loss में है A I M S
L--- Lime (62%)
S--- Silica (22%)
A--- Alumina (6%)
I---- Iron oxide (3%)
M--- Magnesia (2%)
S---- Sulphur Trioxide (1.5%)
Chemical Names:-
Lime-- (CaO)
Silica-- (SiO2)
Alumina--(Al2O3)
Iron Oxide--(Fe2O3)
Magnesia---(MgO)
Sulphur trioxide--(SO3)
Function of cement raw materials or cement compounts:-
Compound | Function |
Lime | It's deficiency reduces strength & setting action. |
Silica | Excess of it causes slow setting. |
Alumina | Responsible for quick setting. |
Iron Oxide | Gives Colour |
Magnesia | Colour & Hardness |
Sulphur Trioxide | Makes cement sound. |
Trick-- S A L I M
S--Silica
A-- Alumina
L-- Lime
I-- Iron Oxide
M-- Magnesia
Unwanted compounds in cement manufacturing.
- Fly Ash :- It increases workability, if excess causes efflorescence, reduces strength.
- Gypsum :-Provides Hardness.
Important:-
- Rate of control's by the controlling amount of SiO2, Iron oxide Fe2O3 and Alumina Al2O3 .
- Alkalis present in cement accelerate setting of cement.
- When the cement is mixed with water this process is called as H.P (Hydration process)
- It is an exothermic reaction.
- When these raw materials ( lime, silica, alumina, iron oxide, sulphur Trioxide) are put in kiln.
- Then heat of hydration takes place and following four compounds are formed.
- These four compounds are known as Bogue's Compounds.
- C3S :- Tri Calcium silicate. (Alite)
- C2S :- Di Calcium silicate. (Belite)
- C3 A :- Tri Calcium Aluminate. (Celite)
- C4 AF :- Tetra Calcium Aluminate Ferrite. (Felite)
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