Cement is actually made by grinding together a mixture of clay and limestone. The micture is then heated in a kiln at 1450 degree centigrade. The resulting granular substance is known as clinker and it is a combination of iron oxide, calcium, silicate and alumina. This process is also known as calcination. Cement is actually a binding material that is used for construction of buildings, bridges etc. Cement is one of the key component that is used for construction. It helps to bind and give strength to the construction. There are two kinds of cement and they are hydraulic cement and non-hydraulic cement.