Page 13 - CONCRETE MATERIALS AND MIXTURE

1.1.1.2 Properties of cement in

concrete mixture

The chemical composition in cement

1. Cement Ingredient and its function

– Lime: It makes the cement sound and provides strength to the cement. Excess
of it in original form causes the cement to expand and disintegrate.

– Silica: It provides strength to the cement. In excess it slows down the setting
of cement.

– Alumina: It provides quick setting property to the cement. In excess it
weakens the strength of cement.

– Calcium Sulphate (Gypsum): It helps in increasing the initial setting time of
cement.

– Iron Oxide: It provides colour, hardness and strength to the cement.
– Magnesium Oxide: It provides colour and hardness to the cement. Excess of it
in free state makes the cement unsound.

– Sulphur Trioxide: In small quantity it makes the cement sound and in excess it
makes the cement unsound.

– Alkalies: In excess it causes efflorescence.