Functions of Cement Manufacturing Constituents.

 Lime (CaO)

• Lime forms nearly two-thirds of the cement. Therefore sufficient quantity of the lime must be in the raw materials for the manufacturing of cement.

• Its proportion has an important effect on the cement. Sufficient quantity of lime forms Dicalcium silicate and tri-calcium silicate in the manufacturing of cement.

• Lime in excess, causes the cement to expand and disintegrate.

    Silica (SiO2)

• The quantity of silica should be enough to form di-calcium silicate and tri-calcium silicate in the manufacturing of cement

• Silica gives strength to the cement.

• Silica in excess causes the cement to set slowly.

Alumina (Al2O3)

• Alumina supports to set quickly to the cement.

• Lowers the clinkering temperature.

• Alumina in excess reduces the strength of the cement.

Iron Oxide (Fe2O3)

• Iron oxide gives colour to the cement.

Magnesia (MgO)

• It also helps in giving colour to the cement.

• Magnesium in excess makes the cement unsound

Calcium Sulphate (or) Gypsum (CaSO4).

• At the final stage of manufacturing, gypsum is added to increase the setting of cement.