There are many types of cement, depending on the type the ingredients will be different.

The two main categories are non-hydrolic and hydrolic.

To make non - hydrolic cement calcium oxide (a product of lime) is mixed with water. This mixture creates slaked lime. The slaked lime hardens by reacting with carbon dioxide in the air.

Hydrolic cement, such as Portland cement, is mostly a fine powder of limestone and a small percentage of other silicates and oxides. It hardens by reacting with water. It creates a cement which is resistant to water.

To make concrete, cement is mixed with gravel and sand.