Cement Ingredients and Their Functions in Construction

Cement is widely used building material in civil construction industry nowadays. When we say cement, we normally mean Portland cement. Different "types of cement" has different percentages of its ingredients. However, typical cement is composed of following ingredients.

Typical cement ingredients and their functions

 

Cement ingredients -

* Calcium Oxide (Lime) 
* Silicon Dioxide (Silica) 
* Aluminum Oxide (Alumina) 
* Calcium Sulphate 
* Iron Oxide 
* Magnesium Oxide 
* Sulphate 
* Alkalis

Calcium Oxide: It is the main ingredient of cement. 61% to 67% of the mass of cement is Calcium Oxide. it is expressed by CaO. In general, we know the calcium Oxide as lime.
Function: It makes cement sound and provides strength to cement.

Silicon dioxide: It is also a major ingredient of cement. It is known as silica. It holds 19-23% of cement mass. It is chemically expressed by SiO2.
Function: The function of silica is also to give strength to cement.

Aluminum oxide: It is called alumina. The chemical name of it is AI2O3. Cement contains 2%-6% alumina of its mass.
Function: It adds quick-setting property to cement.

Calcium Sulphate: It's chemical name is CaSO4.

Function: It helps to increase the initial setting time of cement.

Iron Oxide: It is also called Ferric Oxide. Cement has 0.5%-6% iron oxide of its mass. Iron Oxide's chemical name is Fe2O3. 
Function: It provides color and hardness to cement. It also provides some strength to cement. 

Magnesium Oxide: Magnesium Oxide is expressed by MgO. It also provides color and hardness to cement. 

Sulfate: It is also called Sulphur. It holds 1.5%-4% of the mass of cement. The chemical name of Sulphur is S. 
Function: A very small quantity of Sulphur in the cement makes it (Cement) sound. 

Alkalis: A very small quantity of this may present in the cement.

Source : http://www.acivilengineer.com/2013/04/Cement-Ingredients.html