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As the name of the cement denotes, hydro means water and phobic means against. Hydrophobic cement is obtained by grinding portland cement clinker with a film-forming substance such as oleic acid in order to reduce the rate of deterioration when the cement is stored under unfavourable conditions. It is also known as Hydrographic cement. In this article we discuss about the manufacture, properties, uses, advantages, disadvantages and safety precautions of hydrophobic cement.
Fig 1: Water resistant concrete made of Hydrophobic cement.
Contents:
Manufacture of Hydrophobic Cement
The process of manufacture of this special cement is same as that of portland cement. The clinkers formed in the manufacture of cement are grinded with water repellent film substance such as Oleic Acid or Stearic Acid. These chemicals form a layer on the cement particle and does not allow water to mix and start hydration process in the transportation or storage stage. Anyhow during the mixing process, due to great agitation, this layer of water repellent break and allows the hydration to take place.Properties of Hydrophobic Cement
Table 1: Properties and their values of Hydrophobic cement.| Properties | Value |
| Fineness | 350 m2/kg |
| Soundness | |
| Lechatelier (mm) | 10mm |
| Autoclave | 0.8 % |
| Setting Time | |
| Initial Setting | 30min |
| Final Setting | 600min |
| Compressive Strength | |
| 3days | 16 MPa |
| 7days | 22 MPa |
| 28days | 30 MPa |
| Water Absorption | 0.3 – 1 % |
Uses of Hydrophobic Cement
- Uses in longer storage periods and extremely wet climatic conditions.
- Majorly used in the Tunnel construction as the underground repairs are difficult and costly.
- These cements are used in construction of dams, spillways, under water constructions.
- Used in the structures that are exposed to rain or rain puddling, such as green roofs, other kinds of roofs, parking structures, and plazas.
- Used in drainage system works and manholes.
- Used in water treatment plants , dams and retaining walls.
- It can fix leaky pipes and basements without having to stop the leaking.
Advantages of Hydrophobic Cement
The major advantages of hydrophobic cement are,- Provide durable repairs that will last for long period of times.
- Strength is same as that of ordinary cement.
- Sets and hardens fast, normally three minutes after being mixed with water.
- Setting time is fast, hardens fast, thus it can be painted within one hour of it being applied.
Disadvantages of Hydrophobic Cement
The major disadvantages of hydrophobic cement are,- Does not work on frozen surfaces.
- Cannot be used when the temperature is below 40 degrees Fahrenheit.
- This cement solves the problem of leaking, but does not solve the problems which are due to condensation.
- Needs skilled labour and favourable climatic conditions to use this type of cement.
- Cost is high as it is very expensive.
Health and Safety Precautions of Hydrophobic Cement
- Avoid breathing the dust.
- Avoid any contact with eyes or skin.
- Silica inhaling may cause lung problems, although there is no real evidence silica is a carcinogen.
- The use of protective clothing: gloves or mask is recommended.
