Chemical Ingredients of Cement:

The chief chemical ingredients and their characteristics in ordinary cement are given in Table.

Table: Chief Chemical Ingredients of Cement

The functions and effects of several chemical ingredients of cement are as follows:

Lime

Lime is the major ingredient of cement. It makes the cement sound and also provides strength to the cement. In lime excess makes the cement unsound and causes the cement to expand and disintegrate. The deficiency of lime will decrease the strength and cause the cement to set quickly.

Silica

Silica provides strength to the cement. Silica in excess causes the cement to set slowly.

Alumina

Alumina lowers the clinkering temperature. It provides quick setting property to the cement. Alumina within excess weakens the strength of the cement.

Iron Oxide

Iron oxide provides color, hardness and strength to the cement. It helps the fusion of material at lower temperature during the manufacturing of cement.

Magnesium Oxide

Magnesium oxide provides color and hardness to the cement. Excess magnesium oxide remains in Free State and makes the cement unsound.

Sulphur Trioxide

Sulphur trioxide makes the cement sound if present in very small quantity. Excess sulphur trioxide makes the cement unsound.

Alkalies

Alkalies may be present in a very small quantiy. Alkalies in excess cause efflorescence.