General Knowledge - General Science - Discussion

The most common raw meterial used in cement production are;

* Limestone (supplies the bulk of the lime).
* Clay, marl or shale (supplies the bulk of the silica, alumina and ferric oxide).
* Other supplementary materials such as sand, fly ash/pulverised fuel ash (PFA), or ironstone to achieve the desired bulk composition.

During the cement manufacturing process, upon the cooling of clinker, a small amount of gypsum is introduced during the final grinding process. Gypsum is added to control the "setting of cement". Gypsum is a mineral and is hydrated calcium sulfate in chemical form.

Limestone is calcium carbonate{CaCo3} and clay is the general term including one or more clay combinations with traces of metal oxides and organic matter.

Gypsum is the important role. Whenever the percentage of gypsum increased the hardness will be increased.

Limestone and clay is main raw materials cement but gypsum add reduced rating of cement.

Gypsum is also used in cement manufacturing but why the answer is option c?

Limestone is calcium carbonate and gypsum is also used in making cement.

Gypsum is also used to decrease solidity properties of cement.

Lime stone is calcium carbonate used to cement manufactured.

Limestone and gypson both are highly used in making cement.

Lime stone and gypsum are used for manufacture of cement.