High Alumina Cement
High Alumina Cement also known as calcium aluminate cement or aluminous cement is composed of calcium aluminate.It is manufactured from limestone or chalk and bauxite.
High Alumina Cement (HAC) was first developed in 1925 by a cement producer name Lafarge in United Kingdom.Initially it was used particularly for marine construction because it has good resistant to chemical attacks.It become popular in the year 1950, 60s, 70s because of its property to developed strength rapidly.It was widely used in structural concrete such as pre-cast beams.
Composition of High Alumina Cement
| Constituents | Percentage |
| Silica | 3-8 % |
| Alumina | 37-41 % |
| Lime | 36-40 % |
| Iron Oxide | 9-10 % |
| Titanium | 1.5-2 % |
| Magnesium | 1 % |
| Insoluble Resides | 1 % |
Manufacture of High Alumina Cement
The process of manufacturing of High Alumina Cement is different as compared to Ordinary Portland Cement.The raw materials used are bauxite,chalks and limestone.Bauxite is a residual deposite formed by weathering under tropical conditions of rocks containing aluminium.The raw materials are mixed in a required propertion and grinded into small fragments not larger than 100 mm.These lumps are fed in kiln and heated up to their fusion point which is 1600℃. The moltan materials fall down on steel plate and is send to cool down in rotary kiln.
These clinkers are then grounded finely in tube mills upto the fineness not less than 2500cm^2/gram is achived.
Characteristics of High Alumina Cement
1. It is very resistant to chemical attacks.
2. It has high durability in sulphuric acid.
3. Hardening property of this cement is high.
4. The pH level is low.
5. It has high resistant chemical corrosion that is why is widely used in marine construction,costal construction,sewage pipes etc.
6. The refractive index of this cement is high.
Uses of High Alumina Cement
1. Due to the property of rapid hardening.it is widely used in marine construction and sewer infrastracture.
2. It is also used as refractory concrete where it requirs more strength at very high temperature.
Advantage of High Alumina Cement
1. It has high compressive strength.
2. It can stand at high temperature.
3. It has good resistance against chemical attack.
4. High resistant to fire.
5. It evolves great heat during setting.It is therefore not affected by frost.
Disadvantage of High Alumina Cement
1.Its manufacturing cost is high.
2. As the heat evolution while setting is high,it cannot be used in mass concreting works.
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