Thursday, June 26, 2014
What is Portland cement?
Portland cement
Portland cement is chemically defined as finely ground mixture of Calcium Aluminates and Silicates of varying compositions which hydrates when mixed with water to form a rigid solid structure with good compressive strength.
The name Portland cement came from Portland Rock (Stone) of England.
Composition
1. 2 CaO.SiO2 = Dicalcium
Silicate (C2S) [54%]
2. 3 CaO.SiO2 = Tricalcium
Silicate (C3S) [16.6%]
3. 3 CaO.Al2O3 = Tricalcium Aluminate (C3A)
[10.8%]
4. 4 CaO.Al2O3 Fe2O3= Tetracalcium Alumino Ferrite
(C4AF) [9.1%]
5. MgO [1.5%]
6. CaO
Special types of cement
- White Cement
The
color of the ordinary Portland cement is grayish black due to the presence of
iron oxide as one of the constituents.
If iron oxide can be avoided by suitable
selection of raw materials it is possible to get white cement
- Sulphate Resistant Cement
This
is a cement with higher C2S/ C3S ratio can resist sulphate
attack and corrosion by sea water
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