Cement Grinding
The cooled clinker is fed into the finish grinding mill (which is a tube mill) and ground to a fine powder. At this stage a small quantity of gypsum (3-5%) is added to control the setting time of cement produced.
| Item |
CaO.SiO2 |
2CaO.SiO2 |
3CaO.Al2O3 |
4CaO.Al2O3.Fe2O3 |
| Abbreviated formula |
C3S |
C2S |
C3A |
C4AF |
| Common Name |
Alite |
Belite |
- |
- |
| Principal impurities |
MgO, Al2O3 , Fe2O3 |
MgO, Al2O3 , Fe2O3 |
SiO2, MgO , alkalies |
Ferrite phase , SiO2 , MgO |
| Common crystalline form |
Monoclinic |
Monoclinic |
Cubic, Orthorhombic |
Orthorhombic |
| Range present (%) |
40-60 |
16-30 |
7-15 |
7-12 |
| Average in OPC (%) |
50 |
25 |
8 |
8 |
| Reaction with water |
Medium |
Slow |
Fast |
Medium |
| Contribution to strength |
|
| Early |
Good |
Poor |
Good |
Good |
| Ultimate |
Good |
Excellent |
Medium |
Medium |
| Heat of Hydration |
Medium |
Low |
High |
Medium |
| (cal/g) |
120 |
60 |
320 |
100 |
|
