Acid-Resistant Cement
An acid-resistant cement is composed of the following,
- acid-resistant aggregates such as quartz, quartzites, etc.,
- additive such as sodium flurosilicate and
- aqueous solution of sodium silicate or soluble glass.
The addition of additive sodium fluosilicate accelerates the hardening process of soluble glass and it also increases the resistance of cement to acid and water.
The binding material of acid-resistant cement is soluble glass which is water solution of sodium silicate (Na2O.nSiO2) or potassium silicate (K2O.nSiO2) where n is the glass modulus.
The term glass modulus is used to indicate the ratio of the number of silica molecules to that of alkali oxide molecules and its value in soluble glass varies from 2.50 to 3.50.
The acid-resistant cement is used for acid-resistant and heat-resistant coatings for installations of chemical industry. It is not water-resistant and it fails when attacked by water or weak acids. By adding 0.50 per cent of linseed oil or 2 per cent of ceresit, its resistance to the water is increased and it is then known as the acid and water resistant cement.