Low heat cement is a type of cement that is designed to generate a low amount of heat during the setting process. This is achieved by modifying the chemical composition of normal Portland cement. The changes in composition allow the cement to release less heat as it sets, which can be beneficial in certain applications.
One of the primary advantages of low heat cement is that it reduces the risk of thermal cracking in large concrete structures. When concrete is poured on a large scale, the heat generated during the setting process can cause the concrete to expand and contract. This expansion and contraction can create stress within the concrete, leading to cracking and other forms of damage. By using low heat cement, the amount of heat generated during setting is minimized, reducing the risk of thermal cracking.
In addition to its reduced heat generation, low heat cement has a number of other desirable properties. For example, it tends to have a lower rate of strength gain than traditional Portland cement, which can be beneficial in situations where slower setting is preferred. Low heat cement also tends to have a lower water demand than traditional Portland cement, which can make it easier to work with and can result in lower overall costs.
Low heat cement has a variety of applications in the construction industry. It is commonly used in the construction of large concrete structures, such as dams, bridges, and buildings. It is also used in situations where high temperatures are expected, such as in the construction of nuclear power plants.
Overall, low heat cement is a specialized type of cement that offers a number of advantages over traditional Portland cement. Its unique properties make it a valuable tool for construction professionals, particularly in situations where minimizing heat generation and reducing the risk of thermal cracking are important considerations.
Fig 1: Construction of Dam using Low Heat Cement.
Composition of Low Heat Cement
There is a type of cement that is similar to normal Portland cement, but with some differences in its chemical composition. This particular cement has a lower percentage of tricalcium aluminate (C3A), at only 5%. In contrast, it contains a higher percentage of dicalcium silicate (C2S), at 46%. This slight alteration in the composition results in a unique type of cement that possesses specific properties and benefits. Overall, this cement is a variant of Portland cement, but with adjusted chemical ratios that produce distinct characteristics.
Properties of Low Heat Cement
Table 1: Properties of Low heat Cement
| Item | Standard Value |
| Specific Surface Area | 250 m2/kg Min |
| Initial Setting | 60 minutes Min |
| Final Setting | 12 hours Max |
| Compressive Strength at 7d | 13.0 MPa Min |
| Compressive Strength at 28d | 42.5 MPa Min |
| Breaking Strength at 7d | 3.5 MPa Min |
| Breaking Strength at 28d | 6.5 MPa Min |
| Heat of Hydration at 3d | 230 KJ/kg Max |
| Heat of Hydration at 7d | 260 KJ/kg Max |
Characteristics of Low Heat Cement
Low heat of hydration is a characteristic of cement which is 20% lower than that of OPC cement. This feature is beneficial for construction projects where excessive heat generation can lead to damage or cracks in the structure. Additionally, low heat of hydration means that less water is required for the process of hydration, which is a crucial factor in achieving the desired strength and durability of concrete.
Another advantage of low heat of hydration is that it helps in obtaining high workability of concrete. This is due to the fluid nature of the concrete, which allows for easy and smooth placement of the material. Additionally, concrete with low heat of hydration exhibits good volume stabilization, which helps in reducing the risk of cracking and deformation over time.
Although concrete with low heat of hydration may have lower initial strength, it displays a high growth rate of final strength. This is due to the formation of strong chemical bonds between the cement and aggregates over time, resulting in a more technically superior concrete.
Furthermore, concrete with low heat of hydration exhibits excellent impact erosion and wear resistance. It also has a lower temperature upward value of heat insulation, making it ideal for use in applications where temperature control is necessary. Additionally, it has a super-high performance of chemical corrosion resistance and excellent resistance to drying shrinkage and rupture.
In conclusion, low heat of hydration cement offers numerous advantages over OPC cement, including improved workability, volume stabilization, and superior strength and durability. Its resistance to various forms of damage and wear make it a desirable option for construction projects that require long-lasting and reliable structures.
Compatibility for Admixtures
Low Heat Cement is a type of cement that is known for its low heat of hydration, which makes it ideal for use in large-scale concrete structures that are susceptible to cracking due to temperature changes. One of the advantages of Low Heat Cement is that it is compatible with a variety of other materials commonly used in concrete production.
Chemical Admixtures are substances that are added to concrete to enhance its properties or modify its behavior. These admixtures can improve the workability, durability, and strength of concrete. The good news is that Low Heat Cement is compatible with Chemical Admixtures, which means that these substances can be added to the cement mix without any adverse effects on the final product.
Supplementary Cementitious Materials, or SCMs, are materials that are added to Portland cement to improve its properties. Some common SCMs include Fly Ash, Slag – Ground Granulated Iron Blast-Furnace, and Amorphous Silica. The good news is that Low Heat Cement is also compatible with these materials, which means that they can be added to the mix to create a more sustainable and durable concrete structure.
Uses of Low Heat Cement
Factories such as chemical plants and sulphuric acid factories require specialized surfaces for their road and workroom areas. These surfaces need to be able to withstand the harsh chemicals and substances that are present in the factory environment. To achieve this, special materials are used to construct the surfaces, ensuring that they can withstand the exposure to these hazardous substances.
In addition to factories, large-scale construction projects such as dams, wind turbine plinths, and large raft slabs also require durable surfaces. These projects involve massive footings and structures that require a strong foundation to support them. Therefore, the same specialized materials used in factory surfaces are used in these projects to ensure their durability.
The materials used in constructing these surfaces and structures are carefully selected and designed to withstand the specific environment in which they will be used. They are engineered to provide resistance to the chemicals and substances present in the environment, as well as to maintain their strength and durability over time.
In summary, the construction of surfaces for factories and large-scale projects involves the use of specialized materials that are designed to withstand the harsh conditions of the environment in which they will be used. These materials are carefully selected and engineered to ensure their durability and strength, providing a reliable foundation for the structures they support.
Fig 2: Construction of Power Plant using Low heat cement.
Advantages of Low Heat Cement
Concrete is a widely used construction material that can be found in various structures such as buildings, bridges, and roads. However, in thick concrete sections, there is a potential for thermal cracking which can lead to structural problems. To address this issue, there are additives that can be used to minimise the risk of thermal cracking.
Furthermore, there are additives that can improve the durability performance of concrete. These additives can enhance the final strength of the concrete, increase its resistance to sulphate corrosion, improve its lasting properties, increase its resistance to rupture, and reduce seepage.
For large pours in hydraulic engineering and marine concrete works, additives can increase the workability and pumpability of the concrete, making it easier to handle and transport.
Moreover, the use of additives can significantly improve the later-age concrete strengths, making it more resistant to wear and tear over time. This is particularly important in structures that are subjected to heavy loads or harsh environments.
Lastly, additives can also make the concrete more resistant to sulphate attack on reinforcement, which is a common issue in concrete pipes. With the use of these additives, the lifespan of concrete structures can be extended, reducing the need for frequent repairs and replacements.
Disadvantages of Low Heat Cement
The cement being discussed here has a lower initial strength than Ordinary Portland Cement (OPC). However, its final strength is the same as that of OPC. Despite this similarity in strength, the use of this cement is not recommended in cold weather conditions. Additionally, this cement comes with a higher cost than Ordinary cement.