High Alumina Cement, also referred to as Calcium Aluminum Cement, is produced through a grinding process involving the clinkers of alumina and lime, which are fused or sintered. The production process involves the use of a calcareous material like lime, as well as alumina. The resulting cement has a unique composition that distinguishes it from other types of cement.
The history of High Alumina Cement dates back to the early 20th century. Its development was primarily driven by the need to produce a type of cement that could withstand high temperatures and chemical corrosion. The resulting product was initially used in the construction of structures such as furnaces and chimneys.
High Alumina Cement is characterized by its high resistance to heat, chemical corrosion, and abrasion. These properties make it particularly useful in applications that require materials to withstand extreme temperatures and conditions. Furthermore, it has a rapid hardening time, which makes it ideal for applications where quick setting is required.
High Alumina Cement has a wide range of uses, including the construction of blast furnaces, kilns, and other high-temperature structures. It is also used in the production of precast products such as pipes, tiles, and blocks. Additionally, it is used in the construction of chemical plants and in the lining of sewers and water pipes.
One of the advantages of High Alumina Cement is its exceptional resistance to high temperatures and chemical corrosion. It also has a fast-setting time, which allows for quick construction and repairs. However, it does have some disadvantages. One of the main concerns is its tendency to shrink and crack over time, particularly if exposed to moisture. Additionally, it can be expensive compared to other types of cement.
History of High Alumina Cement
High Alumina Cement was initially created in the United Kingdom in 1925 by the cement producer Lafarge. It was discovered that this type of cement was highly resistant to chemical attacks, making it ideal for use in marine construction. Over time, the popularity of High Alumina Cement grew as its other properties, such as rapid strength gain and ease of manufacturing, were recognized. This made it a popular choice for precast concreting projects.
Fig 1: High Alumina Cement.
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 production process for High Alumina Cement is distinct from that of ordinary Portland cement. Bauxite and lime are used as the raw materials for this cement. The first step is to mix the raw materials in the required proportion, and then grind them into small fragments that measure about 100 mm.
Next, these small fragments are fed into a kiln and heated up to their fusion point, which is a temperature of 1600°C. Once the materials have reached this temperature, they become molten and fall down onto a steel plate. After this, they are sent to cool down in a rotary kiln.
Once the materials have cooled down, they become clinkers, which are then ground finely in tube mills. The grinding process continues until the desired fineness is achieved, which should be no less than 2250 cm2/gram. By following these steps, manufacturers can produce High Alumina Cement to meet the required specifications.
Characteristics of High Alumina Cement
This type of cement boasts several notable characteristics. Firstly, it is highly resistant to chemical attacks, which makes it a popular choice for construction projects that require materials with this type of durability. Additionally, the pH level of this cement is low, which further enhances its chemical resistance.
Due to its high resistance to chemical corrosion, this cement is commonly used in the construction of water pipes, sewage pipes, factory drains, coastal structures, and factory chimneys. Its ability to withstand exposure to harsh chemicals makes it a reliable choice for projects where other materials may not hold up as well.
Another notable feature of this cement is its high refractive index. Additionally, it has been shown to exhibit strong durability in sulphuric acid, which is an important quality for certain industrial applications.
When it comes to hardening, this cement sets quickly. This attribute makes it a preferred choice for projects where a fast setting time is crucial. Finally, it can also act as a bonding material in refractory castables. This is because it can form a ceramic bond at high temperatures, which makes it useful in certain high-temperature applications.
Uses of High Alumina Cement
High alumina cement is a popular choice for marine construction and sewer infrastructure due to its rapid hardening and strength properties. This type of cement is able to set quickly, making it ideal for use in areas where time is of the essence. Additionally, its strength makes it a durable option for structures that will be exposed to harsh environmental conditions.
In addition to its use in marine and sewer construction, high alumina cement is also commonly used in refractory concretes. This is because it is able to maintain its strength even at very high temperatures, making it a valuable material for high-temperature applications. As a result, it is often used in industrial settings where extreme heat is a factor, such as in furnaces or kilns.
Overall, the unique properties of high alumina cement make it a versatile and valuable material for a wide range of construction and industrial applications. Its strength and rapid hardening make it ideal for use in marine and sewer infrastructure, while its ability to withstand high temperatures makes it a valuable component in refractory concretes.
Fig 2: Use of High Alumina Cement in Marine precast construction.
Advantages of High Alumina Cement
High Alumina Cement offers various advantages over other types of cement. One of the benefits is that it allows more time for mixing and placing due to its longer setting time. Additionally, it has excellent resistance to chemical action and can withstand high temperatures, making it suitable for use in high-temperature applications.
Moreover, High Alumina Cement is highly resistant to frost action, as the heat generated during its setting process is more significant than other types of cement. It is also incredibly reactive and has a very high compressive strength, making it an ideal choice for applications where high strength is required.
Finally, High Alumina Cement is highly resistant to fire, making it ideal for use in fireproof applications. Its superior fire resistance properties make it a popular choice in the construction of fireplaces, chimneys, and other high-temperature applications where fire resistance is crucial.
Disadvantages of High Alumina Cement
High alumina cement is known to have some drawbacks that must be considered before use. Firstly, the manufacturing cost of this cement is high due to the high heat required during the manufacturing process. Secondly, the fineness of this cement is maintained at a minimum of 2250 cm2/gram, which is very fine. Therefore, it is important to take precautions to ensure that it does not come in contact with the human eye or mouth, which could cause harm. Lastly, the heat released during the setting process of high alumina cement is high, which makes it unsuitable for use in mass concreting projects. These disadvantages should be taken into account when deciding whether to use high alumina cement for a particular construction project.