What makes this cement 'hydrophobic'?

A film-forming substance, like oleic acid or stearic acid, is inter-ground with the cement clinker, coating the particles to repel water during storage (Clause 4.1).

How is the water repellency tested?

A sample is sprayed with water for 1 minute and then kept in a high humidity environment for 1 hour. At least 50% of the cement must remain fine enough to pass a 150-micron sieve, indicating it has not lumped due to moisture (Clause 6.6).

Are the strength requirements the same as normal cement?

The minimum compressive strength requirements (16 MPa at 3 days, 22 MPa at 7 days, 33 MPa at 28 days) are equivalent to those for 33 Grade OPC, ensuring comparable final performance (Table 2).

Does the hydrophobic property affect the final concrete?

No. The hydrophobic film is broken down by the abrasion of aggregates during mixing, allowing the cement to hydrate and behave like ordinary Portland cement in the hardened concrete.

IS 8043

: 1991

Hydrophobic Cement - Specification

CurrentSpecializedSpecificationBIMMaterials Science · Cement

Download PDF BIS Portal Google

This standard specifies the requirements for hydrophobic Portland cement, which is designed to resist water absorption during transport and storage. It is manufactured by inter-grinding Portland cement clinker with a hydrophobic agent, making it suitable for use in high-humidity environments or for projects with long storage durations before use.

Specifies requirements for hydrophobic cement, designed to resist deterioration during storage in humid conditions.

Quick Reference Values

Minimum 28-day Compressive Strength33 MPa

Minimum Fineness (Specific Surface)225 m²/kg

Initial Setting Time (min)30 minutes

Final Setting Time (max)600 minutes

Maximum Loss on Ignition (LOI)5.0 %

Water Repellency Test (min passing 150-micron sieve after 1 hr)50 %

Practical Notes

The hydrophobic film on cement particles is broken during the mixing process, allowing for normal hydration. Ensure thorough and extended mixing compared to OPC.

While its ultimate strength is comparable to OPC, its early strength gain may be slightly slower. This should be considered for formwork removal schedules.

Ideal for remote construction sites or regions with high rainfall/humidity where cement warehouse conditions are not ideal.