High Alumina Cement, also known as calcium aluminum cement, is produced through a grinding process of alumina and calcareous materials like lime that have been fused or sintered. The resulting cement is known for its high alumina content, which gives it unique properties and characteristics.
The history of High Alumina Cement dates back to the early 20th century when it was first discovered and developed. Since then, it has been widely used in various industries and applications due to its superior strength and durability.
The composition of High Alumina Cement is mainly made up of alumina, lime, and other minerals. The exact composition can vary depending on the manufacturer and the intended use of the cement.
The manufacturing process of High Alumina Cement involves grinding the clinkers of alumina and calcareous materials such as lime. This is followed by a fusion or sintering process, which helps to create a homogeneous and stable product.
High Alumina Cement is known for its unique characteristics, such as high early strength, high resistance to chemical attacks, and low heat of hydration. These properties make it ideal for use in high-stress applications such as in the construction of bridges, tunnels, and high-rise buildings.
Despite its advantages, High Alumina Cement also has some disadvantages. It is more expensive than other types of cement, and it can be prone to cracking and shrinkage over time. Additionally, it has a shorter shelf life than other types of cement and must be used within a certain period.
Overall, High Alumina Cement has proven to be a valuable and versatile material in various industries and applications. Its unique properties and characteristics make it an excellent choice for high-stress applications where strength and durability are essential.
History of High Alumina Cement
High Alumina Cement was originally created in the United Kingdom in 1925 by Lafarge, a cement producer. Its primary application was for marine construction due to its resistance to chemical attacks. Over time, it became more popular as its unique properties, such as rapid strength gain and ease of manufacture, were discovered. High Alumina Cement’s versatility and reliability led to its widespread use in precast concreting, further increasing its popularity.
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
High Alumina Cement is manufactured using a different process as compared to Ordinary Portland Cement. This cement is made from a mixture of bauxite and lime, which are the raw materials used in the production process. The first step in the process is to mix the raw materials in the correct proportions. After this, the mixture is ground into small fragments of around 100 mm.
The next step involves feeding these small fragments into a kiln and heating them up to their fusion point, which is at a temperature of 1600°C. The molten material falls onto a steel plate and is then sent to cool down in a rotary kiln. This cooling process helps to form clinkers, which are then finely ground in tube mills until they achieve a fineness level of not less than 2250 cm2/gram.
In summary, High Alumina Cement is made from bauxite and lime, which are mixed in the right proportions and ground into small fragments. These fragments are then heated to their fusion point in a kiln before being cooled down in a rotary kiln to form clinkers. The clinkers are then finely ground in tube mills until they reach a certain level of fineness.
Characteristics of High Alumina Cement
This particular type of cement boasts several unique characteristics that make it highly valuable in various construction applications. Firstly, it exhibits exceptional resistance to chemical attacks, making it an ideal choice for environments where chemical corrosion is a concern. Its low pH level and high resistance to chemical corrosion also make it an excellent option for constructing water pipes, sewage pipes, factory drains, coastal structures, and factory chimneys.
In addition to its chemical resistance, this cement also has a high refractive index, which contributes to its durability in sulphuric acid. It also hardens quickly, making it an efficient option for construction projects with tight timelines. Furthermore, when added to refractory castables, it acts as a bonding material by forming a ceramic bond at high temperatures.
Overall, this cement is a versatile and valuable option for a wide range of construction applications due to its impressive chemical resistance, durability, and bonding properties. Its unique characteristics make it a go-to choice for building structures and materials that require high levels of protection against chemical corrosion and other types of wear and tear.
Uses of High Alumina Cement
High alumina cement is a popular choice in the construction of marine structures and sewer infrastructure due to its quick hardening and strong properties. This type of cement is able to provide rapid strength, making it an ideal option for these types of applications where durability and reliability are essential.
In addition to its use in marine and sewer construction, high alumina cement is also utilized in the creation of refractory concretes. This type of concrete is specifically designed to withstand high temperatures, and as such, requires a cement that can provide exceptional strength under extreme conditions. High alumina cement is able to meet this requirement, making it a top choice for refractory concrete applications.
Fig 2: Use of High Alumina Cement in Marine precast construction.
Advantages of High Alumina Cement
High Alumina Cement (HAC) is known for its numerous advantages in construction. One such advantage is that it has a longer setting time, allowing more time for the mixing and placing of the cement. Additionally, HAC has excellent resistance to chemical action and can withstand high temperatures, making it suitable for use in extreme conditions.
Another benefit of HAC is its ability to resist frost action. This is due to the heat generated during the setting process, which helps to prevent the cement from being affected by frost. Moreover, HAC is highly reactive and boasts exceptional compressive strength. This makes it an ideal choice for construction projects where strength is a crucial factor.
Lastly, HAC is highly resistant to fire, which is a crucial property in structures that may be exposed to fire hazards. With its numerous advantages, High Alumina Cement is a popular choice in various construction projects, from buildings to bridges and beyond.
Disadvantages of High Alumina Cement
High alumina cement, while having its benefits, also comes with a few disadvantages. One of these is that the heat required to manufacture this cement is high, resulting in a higher manufacturing cost. Additionally, the fineness of this cement is not less than 2250 cm2/gram, which is very fine. This means that precautions must be taken to ensure that the cement does not come into contact with the human eye or mouth.
Another disadvantage of high alumina cement is that the heat evolution during the setting process is high. This means that it is not suitable for use in mass concreting works. This is because the heat generated during the setting process can cause thermal cracking and other issues in large-scale projects.
Overall, while high alumina cement has its benefits, such as high early strength and resistance to acidic environments, it is important to be aware of these disadvantages when considering its use in construction projects.