cement constituents

Lime 

• Deficiency in lime reduces the strength of cement.
• Deficiency in lime causes cement to set quickly.
• Excess lime make cement unsound.
• Excessive presence of lime cause cement to expand and disintegrate.
• Its Percentage in cement is 60-65%

Silica 

• Sufficient quantity of silica should be present in cement to dicalcium and tricalcium silicate.
• Silica imparts strength to cement.
• Silica usually present to the extent of about 30 percent cement
• Its Percentage in cement is 17-25%

Alumina 

• Alumina imparts quick setting property to the cement.
• Clinkering temperature is lowered by the presence of requisite quantity of alumina.
• Excess alumina weaken the cement.
• Its Percentage in cement is  3-8%

Magnesia 

• Magnesia should not be present more than 2% in cement.
• Excess magnesia will reduce the strength of the cement.
• Its Percentage in cement is  1-3%  

Iron oxide 

• Iron oxide imparts color to cement.
• It acts as a flux.
• At a very high temperature it imparts into chemical reaction with calcium and aluminum to form tricalcium aluminoferrite.
• Tricalcium aluminoferrite imparts Hardness and strength to cement.
• Its Percentage in cement is   0.5-6

Calcium sulphate 

• This is present in cement in the form of gypsum(CaSO4.2H2O)
• It slows down or retards the setting action of cement.
• Its Percentage in cement is 0.1-0.5 

Sulphur Trioxide 

• Should not be present more than 2%.
• Excess Sulphur Trioxide causes cement to unsound.

Alkalis

• Should not be present more than 1%.
• Excess Alkali matter causes efflorescence.