Functions of Various Ingredients of Cement

Functions of Various Ingredients of Cement

1.Lime : Lime plays a very important role on the quality of cement because it forms about 63 percent of cement. To from the required silicates and aluminated of calcium, a sufficient quantity of lime must be present. A deficiency in lime reduces the strength of cement and causes it to set quickly. On the otherhand , and excess will make cement unsound and cause its to expand and disintegrate.

2.Silica : Sufficient quantity of silica should be present in cement to dicalcium and tricalcium silicate. Silica imparts strength to cement and usually present to the extent of about 30 present cement.

3.Alumina : It  impartes quick setting property to cement, clinkering temperature is lowered by the presence of requisite quantity of a alumina. But an excess of alumina weakens the cement.

4.Magnesia : Magnesia should not be present more than 2 present in cement. An excess is harmful and will reduce the strength of cements.

5.Iron oxide : It imparts colour to cements. It acts as a flax. At a very high temperature it enters into chemical recaction with calcium and aluminium to from tricalcim aluminoferrite. This new compound imparts hardness and strength to cement.

6.calcium sulphate : This is present in cement in the form of gypsum. It shows down or retards the setting of cement.

7.Sulphur Trioxide :It should not be present more than 2 present in cement. An excess causes cement to become unsound.

8.Alkalies : These should not be present  more than I present in cement because excess alkaline matter causes efforscence.

Two terms used in table 7.2 require explanation. The insoluble determined by treting with hydrochlonic aid, is a measure of adulteration of cement. Lartely arishing from impurities in gypsum. The insoluble residue should not exceed 1.5 present.