Chemical Composition of Cement
The raw materials used for the manufacture of cement consist mainly of lime, silica, alumina, and iron oxide. These oxides interact with one another in the kiln at high a temperature to form more complex compounds. Â
Approximate Oxide Composition Limits of Ordinary Portland Cement
| Oxide Content | Percentage |
| Cao | 60 – 67 |
| SiO2 | 17 – 25 |
| Al2O3 | 3.0 – 8.0 |
| Fe2O3 | 0.5 – 6.0 |
| MgO | 0.1–4.0 |
| Alkalies (K2O, Na2O) | 0.4 – 1.0 |
| SO3 | 1.3 – 3.0 |
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