Rapid hardening cement, also known as High-Early Strength Portland Cement, is designed to achieve high strength in a shorter period of time than conventional cement. While conventional cement may take up to 7 days to achieve a certain level of strength, rapid hardening cement can achieve the same level of strength in just 3 days.
The manufacturing process for rapid hardening cement involves grinding and firing raw materials at a higher temperature than those used for conventional cement. This results in a finer product with a higher surface area, which allows for faster hydration and setting times.
One of the key properties of rapid hardening cement is its ability to achieve high strength in a short period of time. This makes it a popular choice in construction projects where time is of the essence. Additionally, it has a low permeability, which makes it ideal for use in structures that require protection against water penetration.
Rapid hardening cement can be used in a variety of applications, including precast concrete, road and bridge construction, and repair work. It is also commonly used in cold weather concreting, where it can help speed up the setting and hardening process.
Some of the advantages of rapid hardening cement include its ability to achieve high strength in a short period of time, its low permeability, and its versatility in various construction applications. However, it should be noted that rapid hardening cement may not be suitable for all projects, and should be carefully considered based on the specific needs and requirements of the project at hand.
Manufacture of Rapid Hardening Cement
Rapid hardening cement is manufactured through the dry process of cement manufacture. The raw materials used in the production of this cement are limestone and shale. These raw materials are heated at extremely high temperatures to form clinkers. The resulting clinker mixture of lime and shale is then mixed with a small amount of gypsum and ground very finely to create rapid hardening cement.
The primary difference between rapid hardening cement and ordinary Portland cement lies in the quantity of limestone, specifically tri-calcium silicate, used as a raw material. The increased amount of tri-calcium silicate gives the rapid hardening cement its high early strength, making it a desirable option for applications that require a fast-setting cement.
Overall, the process of manufacturing rapid hardening cement involves carefully selected raw materials, high-temperature heating, and a specific ratio of components to achieve the desired strength and set time. With its unique composition, rapid hardening cement has become a popular choice for various construction projects.
Fig 1: Use of Rapid Hardening Cement for Concrete Pavement.
Properties of Rapid Hardening Cement
Rapid hardening cement is a type of cement that gains strength faster than Ordinary Portland Cement (OPC). In just 3 days, it can develop 7 days strength of OPC with the same water cement ratio. However, it emits more heat during setting, which makes it unsuitable for mass concreting. The final setting time of rapid hardening cement is the same as OPC, which is 30 minutes for initial setting and 600 minutes for final setting.
The soundness of rapid hardening cement is Autoclave-0.8% and Le-Chatlier’s-10mm. Additionally, this type of cement has a specific surface greater than 3250 cm2/gm, and it is lighter and more expensive than OPC. One of the benefits of rapid hardening cement is that its short curing period makes it more economical. However, it should be stored in a dry place because its quality can deteriorate due to premature carbonation and hydration.
Uses of Rapid Hardening Cement
Rapid hardening concrete, also known as high early strength concrete, is a type of concrete that is widely used in construction projects where quick removal of formwork is necessary for reuse. This type of concrete gains strength rapidly, allowing for the formwork to be taken down earlier than traditional concrete, which can help speed up construction timelines.
One of the primary applications of rapid hardening concrete is in construction projects that require high early strength. The quick setting and hardening properties of this type of concrete make it ideal for use in road pavements where it is essential to open the road to traffic as soon as possible. This allows for greater efficiency and reduced disruptions to traffic flow during construction.
In addition to its use in construction projects, rapid hardening concrete is also popular in industries that manufacture concrete products such as slabs, posts, electric poles, and block fences. This is because moulds can be released quickly due to the rapid hardening properties of the concrete. This saves time and increases productivity in the manufacturing process.
Another advantage of using rapid hardening concrete is its suitability for cold weather concreting. When the temperature drops, traditional concrete can be at risk of freezing, leading to cracking and other structural issues. Rapid hardening concrete generates heat during the hydration process, which helps to protect the concrete from freezing and maintain its structural integrity.
Overall, rapid hardening concrete is a versatile material that offers many benefits over traditional concrete. Its ability to gain strength quickly makes it a popular choice for construction projects that require fast turnarounds, while its ability to withstand cold weather conditions and quick mould release time makes it a go-to option for manufacturers of concrete products.
Advantages of Rapid Hardening Cement
Rapid hardening cement is a type of cement that offers several advantages over other types of cement. One of the most significant advantages is that it requires a short period of curing. This is beneficial because it allows for faster construction, and the traffic can be opened early in areas such as road pavements.
Another advantage of using rapid hardening cement is that it is resistant to sulphate attacks. This means that it can withstand harsh environments without being damaged. Additionally, shrinkage is reduced during curing and hardening of cement. This is important because it ensures that the structure will remain intact and stable over time.
Rapid hardening cement is often used in manufacturing precast slabs, posts, electric poles, and concreting in cold countries. It gains high strength in the early days, and the form work can be removed earlier as compared to other types of cement. This is beneficial because it allows for faster construction and reduces costs.
Lastly, rapid hardening cement is very durable and matches the fast pace of construction and budgets required to make projects operational. Overall, the use of rapid hardening cement is an excellent option for construction projects that require fast results without compromising on quality and durability.