Cement is a mixture of calcium silicates and aluminates. The main raw materials for its manufacture are: MCQ with Answer and Explanation

Portland cement is made by heating a mixture of limestone (CaCO₃) and clay (containing SiO₂, Al₂O₃, Fe₂O₃) in a rotary kiln at high temperature, forming clinker, which is then ground with a small amount of gypsum to control setting. Gypsum alone is added as a retarder, not raw material. The major compounds formed are tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite.