Types of Cement

Hydrophobic / Water-Repellent Cement

Hydrophobic cement is the name given to  Portland cement to which a hydrophobic /water-repellent agent has been added. Water-repellent cements are usually made by adding a small amount of water-repellent film forming additive such as stearate (sodium, aluminum, or other), oleic acid etc to cement clinker during final grinding. This film gives to the cement a large degree of protection against deterioration during storage.

It repels water due to a film coated on grains, making it ideal for long storage but when mechanically mixed with aggregates, the film breaks open and gives same properties as OPC. Further, it helps a little air entraining for easy workability.

Manufactured in either white or gray color, water repellent cements reduce capillary water transmission when there is little to no pressure but do not stop water vapor transmission. They are used in tile grouts, paint, and stucco finish coats.

This cement is favoured where poor storage/transportation conditions for cement (prior to utilization in mortars or concrete) do not favour the successful employment of either ordinary or rapid-hardening Portland cement (ASTM Types I and III). Such conditions arise in hostile climates or in humid conditions.

The same hydration products are formed as with Portland cements. However, setting may be retarded somewhat by the hydrophobic agent. Suitable compressive strengths are readily achievable.