High Alumina Cement – Manufacture, Characteristics and Uses

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High Alumina Cement is manufactured by grinding the clinkers of alumina and calcareous material such as lime by fusing or sintering process. This cement is also known as calcium aluminum cement. In this article we discuss about the history, composition, manufacture, characteristics, uses, advantages and disadvantages.

History of High Alumina Cement

High Alumina Cement was first developed in United Kingdom in 1925 by a cement producer by name Lafarge. As it was found to be resistant to chemical attacks it was primarily used for marine construction. Its popularity rose when the properties of this cement such as rapid strength gain and easy to manufacture were found out and widely used for precast concreting.

Composition of High Alumina Cement

Table 1 : Composition percentage of constituents.

Constituents	Content 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 manufacture of High Alumina Cement is different compared to that of ordinary portland cement. Bauxite and lime are used as the raw material. The raw materials are mixed in the required proportion and grinded into small fragments of 100 mm. These lumps are fed in kiln and heated up-to their fusion point which is 1600°C. The molten material fall down on the steel plate and it is send to cool down in rotary kiln. These clinkers are then grounded finely in tube mills unto the fineness not less than 2250 cm²/gram is achieved.

Characteristics of High Alumina Cement

The characteristics of this cement are,

1. It is very resistant to chemical attacks.
2. The pH level is low.
3. High resistant to chemical corrosion, due to which it is used for  construction of water pipes, sewage pipes, factory drains, coastal constructions and in factory chimneys.
4. The refractive index of this cement is high.
5. It has high durability in sulphuric acid.
6. Hardening property of this cement is fast.
7. It acts as a bonding material when added in refractory castables because it forms ceramic bond at high temperatures.

Uses of High Alumina Cement

1. Due the property of rapid hardening and strength, it is widely used in marine construction and sewer infrastructure.
2.  High alumina cement is also used in refractory concretes where it requires more strength at very high temperature.

Advantages of High Alumina Cement

The advantages of High Alumina Cement are as follows,

1. Due to the more setting time, time for mixing and placing is more.
2. The resistance for the chemical action is good.
3. Can withstand high temperature.
4. Frost action is low as the heat evolved is more during setting.
5. High alumina cement is very reactive and has very high compressive strength.
6. High resistant to fire.

Disadvantages of High Alumina Cement

The disadvantages of high alumina cement are as follows,

1. As the heat required for the manufacture of this cement is more, the manufacturing cost of this cement is high.
2. As the fineness is kept not less than 2250 cm²/gram, which is very fine. Care to be taken that it doesn't come in contact with human eye or mouth.
3. As the heat evolution while setting is high, it cannot be used in mass concreting works.