List the raw materials required in the manufacture of portland cement. What is the role of gypsum in it?

List the raw materials required in the manufacture of portland cement.

1.	List the raw materials required in the manufacture of portland cement. What is the role of gypsum in it?
Answer» Solution :The purpose of ADDING gypsum to cement is to slow down the PROCESS of setting of the cement so that it GETS sufficiently hardened. Raw MATERIALS used for the manufacture of portand cement.