High Alumina Cement (HAC), also known as calcium aluminate cement, (CAC), or aluminous cement, is made of calcium aluminates. This is in contrast to Portland cement, which is made of calcium silicates. It is made from limestone, chalk, and bauxite.
High Alumina Cement Manufacturing
The raw materials of High Alumina Cement are lime and bauxite. Mix the raw materials in the correct proportions and then grind them into smaller pieces of approximately 100 mm. These lumps are then fed into a kiln, where they are heated to their fusion temperature of 1600°C. The molten materials are then deposited on to the steel plate. It is then sent to cool in a rotary kiln. These clinkers then get ground finely in tube mills until they are no less than 2250 cm /gram.
Characteristics High Alumina Cement
These are the characteristics of this cement
- It is highly resistant to chemical attacks.
- The pH level is very low.
- It is highly resistant to chemical corrosion and is used in the construction of water pipes, sewer pipes, factory drains, factory chimneys, and coastal constructions.
- This cement has a high refractive index.
- It is resistant to sulphuric acids.
- This cement has a fast hardening process.
- It forms a ceramic bond at high temperatures and acts as a bonding agent when it is added to refractory castings.
- It is used extensively in marine construction and sewer infrastructure due to its strength and rapid hardening.
- Refractory concretes that require more strength at high temperatures can also use high alumina cement.
Composition:
Monocalcium aluminate is the main active component of calcium aluminate concrete cement. It may also contain other calcium aluminates and a variety of less reactive phases that are formed from impurities in raw materials. There are many compositions that can be used depending on the application and purity of the aluminum.
Advantages of High-Alumina Cement
- This cement takes more than 3.5 hours to set up. The final setting time takes approximately 5 hours. This allows for more time to mix and place operations.
- It can withstand high temperatures.
- It produces a lot of heat when it sets. Frost does not affect it.
- It is more resistant to acid action.
- It sets quickly and achieves a higher ultimate strength within a shorter time. Its strength after 1 Day is approximately 40 N/mm 2, and after 3 Days is about 50 N/mm 2.
- Its setting action is largely dependent on chemical reactions. Therefore, it is not necessary that you grind it to a fine powder.
High Alumina Cement’s Disadvantages
Here are some of the drawbacks to High Alumina cement.
- It is important to take extreme care to ensure that the cement doesn’t come into contact with ordinary cement or lime.
- It is not recommended for mass construction because it generates high heat and sets quickly.
- It’s expensive
- High Alumina Cement is used in a variety of applications
- HAC can also be used in refractory concretes that require more strength at high temperatures.
- Concrete construction, where strong concretes are required to develop quickly, even at low temperatures.
- It is used as a protective liner against microbiological corrosion in the sewer infrastructure
- Blended cement formulations require this component for various properties, such as controlled expansion and ultra-rapid strength.
- For their high resistance against biogenic sulfur corrosion.