Civil Engineering ⇒ Topic : Cement
|The product obtained by burning and crushing
to powder either stone containing 1/5th or 2/5th
clay and remaining carbonate of lime or an
intimate mixture of well proportioned calcareous
and argillaceous materials is called cement |
composition of Portland cement is as follows :
1. Calcium oxide = 60 to 65%
2. Silica = 20 to 25%
3. Aluminium oxide = 4 to 8%
4. Ferrous oxide = 2 to 4%
5. Magnesium oxide = 1 to 3%
6. Sulphur Trioxide = 0.5 to 3%
Initial setting timeIt is the time for attaining that stage in the process of hardening after which any cracks that may appear do not reunite.
Final setting time
It is the time for attaining sufficient strength and hardness.The initial setting time for cement should not be less than 30 minutes and the final setting tinte not more than 10 hours.
The maximum BOD removal efficiency of an oxidation pond is.....
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