For construction in places of high humidity and frequent rainfall, Hydrophobic Cement or Waterproof Cement is used.It is obtained by grinding ordinary Portland cement clinker with water repellent film-forming substance such as oleic acid, and stearic acid. The water-repellent 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-repellent material will entrain certain amount of air in the body of the concrete which incidentally will improve the workability of concrete. This cement is most used In places where we get plenty of rainfall in the rainy season had have high humidity in other seasons.Due to this weather conditions Ordinary cement gets deteriorated and loses some if its strength,whereas Hydrophobic Cement does not lose any strength and very effective for construction in these type of areas.
Other than entraining a small quantity of air bubbles the properties of hydrophobic cement is nearly the same as that ordinary Portland cement . 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 repellent material.These materials protects the cement from bad effects of weather during transportation and storage. Due to adding of additional materials he cost of this cement is nominally higher than ordinary Portland cement.
