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.

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