Question

The chemical ingredient of cement which provides quick setting property to the cement is

1.

Lime

2.

Silica

3.

Alumina

4. Iron oxide

Answer 1

Correct Answer - Option 3 :

Alumina

The following table shows the composition of cement and their properties.

Ingredients	Within limit	If in excess
Lime (62 – 65%)	Controls strength and soundness	Makes the cement unsound and it expands and disintegrate
Silica (17 - 25 %)	Adds strength to cement, as it forms C2S and C3S	Causes slow setting of cement
Alumina (3 - 8 %)	Provides quick setting of cement and lowers the clinkering temp	Lowers the strength
Iron oxide (3 - 4 %)	Provides color, hardness , strength and helps in fusion of raw material
Magnesia (1 - 3 %)	Provides hardness and color Decreases shrinkage	Makes the cement unsound
Alkalies (0.2 - 1 %)	Should be in limit	Alkali aggregate reaction Efflorescence and staining