Rapid hardening cement, also known as high early strength cement, achieves strength more quickly than standard Portland cement. The faster strength gain is achieved by grinding the cement to a finer consistency, as well as including a variety of chemical additives. This cement is widely used in construction projects that require a rapid turnaround time.
Rapid hardening cement is most commonly used for concrete flatwork such as slabs or sidewalks. It can also be used for pre-cast concrete and shotcreting, but it’s important to remember that the higher early strength of this cement means it will have a lower ultimate strength at 28 days.
Rapid hardening cement should be used with caution in cold weather applications because it will freeze more quickly than standard Portland cement. In warm weather applications it needs to be protected from rapid drying and heat generated by hydration.
The primary benefit of rapid hardening cement is the rate in which it develops high strength, relative to that of ordinary portland cement. This is due to the clinker having a low tricalcium aluminate (C3A) content and being finely ground. The higher early strength of rapid hardening cement can be used for construction purposes where it is important that concrete be placed into service quickly. Because the hydration process takes place at a faster rate, the heat released by the concrete during hydration is also higher. This usually results in a more uniform temperature gradient and stress distribution through out the structure, which could reduce thermal cracking and shrinkage cracking.
Since rapid hardening cement has a lower percentage of C3A, it will produce less heat than ordinary portland cement and it will also have a lower drying shrinkage. The lower C3A content can also lead to improved sulfate resistance by reducing the amount of ettringite formed by sulfate attack. Rapid hardening cement reduces the amount of water needed to achieve a given slump because it is finer than ordinary portland cement, but this should be done with caution because too little water will increase bleeding and segregation.
Rapid hardening cements are commonly used for construction projects like constructing bridges,
Rapid hardening cement is a hydraulic cement that sets, and gains strength rapidly. The hydration products are essentially the same as those of ordinary Portland cement. According to the American Society for Testing and Materials (ASTM) in the United States, rapid hardening cement is essentially a portland cement that increases strength at an earlier age. This increased early strength is achieved by grinding the mix to a finer size, modifying the chemical composition and increasing the percentage of C3A. The fineness of this cement also allows greater reactivity with admixtures such as fly ash.
Rapid Hardening Portland Cement is similar to ordinary Portland cement except that it is ground finer and contains more C3A. For this reason, it has a higher rate of heat evolution and offers certain advantages in producing precast concrete products where rapid strengths are required for demoulding or handling.
Cement is a material that holds the other materials together. Rapid hardening cement is made to set quickly and harder than the original cement.
Rapid hardening cement is also known as high early strength cement. It is manufactured by increasing the content of tri-calcium aluminate (C3A) in the cement which results in quick setting of the concrete. The initial setting time of rapid hardening cement is 10 minutes, whereas it takes 30 minutes for ordinary Portland cement to set. This is why rapid hardening cement can be used for projects that need quick setting time such as precast elements, temporary roads construction, manufacturing of small concrete structure etc.
Rapid Hardening Cement**
The properties of rapid hardening cement are:**
1. Initial setting time of this type of cement is 10 minutes which can be reduced to 5 minutes by adding gypsum to its mixture in a certain quantity.**
2. It sets 2-3 times faster than ordinary portland cement i.e. final setting time is 20-30 minutes only.**
3. It has high early strength which makes it very useful in situations where fast construction or repair work is required such as precast elements production, temporary roads construction etc. It
Rapid hardening cement is a type of hydraulic cement that sets and hardens faster than ordinary Portland cement. Rapid hardening cement also attains higher strength compared to ordinary Portland cement.
Rapid hardening cement is produced by increasing the grinding fineness of ordinary Portland cement. This makes more grains available to hydrate, resulting in faster development of strength.
Rapid hardening cement is generally used where quick strength development is required. Rapid hardening cements are specified where early form removal or early application of service loads are required.
The uses of rapid hardening cement include: making concrete roads, concrete pavements, floor slabs, shop floors, precast concrete products and RCC works where forms can be removed earlier.
Rapid Hardening Cement
Rapid hardening cement is very similar to ordinary Portland cement (OPC). The only difference between these two cements is that the rate of hydration of the rapid hardening cement is higher than that of OPC. In other words, the strength development capacity of this cement is very high. Rapid hardening cement contains more tri-calcium silicate and di-calcium silicate. Therefore, it results in faster setting and hardening.
It produces high early strength as compared to OPC. Moreover, it has more resistance to chemical attack and sulfate action. This cement has comparatively a lower percentage of lime content as compared to OPC. Whereas, it has a higher percentage of silica content than the ordinary Portland cement. The standard consistence value for rapid hardening Portland cement is 30% which is greater than OPC that is 28%.
In this article, we will discuss the properties, composition, uses, advantages, and disadvantages of rapid hardening Portland cement.
Rapid hardening Portland cement is similar to ordinary Portland cement. It contains higher C3A content and as a result, it generates higher heat of hydration and has greater strength development at an early stage than ordinary Portland cement.
Rapid hardening Portland cement is used in concrete when the need of high early strength is required. For example, in the case of precast concrete members, the rapid hardening variety is preferred to increase the rate of production.
The use of rapid hardening Portland cement results in:
1. Higher rate of gain of strength.
2. Early removal of formwork.
3. Early application of load on structure.