- Hydrophobic cement is obtained by grinding ordinary Portland cement clinker with water repellant film-forming substance such as oleic acid, and stearic acid.
- The water-repellant film formed around each grain of cement, reduces the rate of deterioration of the cement during long storage, transport, or under unfavourable conditions.
- The film is broken out when the cement and aggregate are mixed together at the mixer exposing the cement particles for normal hydration. The film forming water-repellant material will entrain certain amount of air in the body of the concrete which incidentally will improve the workability of concrete.
- Some places get plenty of rainfall in the rainy season and have high humidity in other seasons.The transportation and storage of cement in such places cause deterioration in the quality of cement. In such far off places with poor communication system, cement perforce requires to be stored for long time.
- Ordinary cement gets deteriorated and loses some if its strength, whereas the hydrophobic cement which does not lose strength is an answer for such situations.
- The properties of hydrophobic cement is nearly the same as that ordinary Portland
cement except that it entrains a small quantity of air bubbles. The hydrophobic cement is made actually from ordinary Portland cement clinker. After grinding, the cement particle is sprayed in one direction and film forming materials such as oleic acid, or stearic acid, or pentachlorophenol, or calcium oleate are sprayed from another direction such that every particle of cement is coated with a very fine film of this water repellant material which protects them from the bad effect of moisture during storage and transporation. The cost of this cement is nominally higher than ordinary Portland cement.