What is Accelerated hydration in concrete? Explain in details of Accelerated hydration in concrete with example.
Accelerated hydration in concrete refers to the situation where the chemical reaction between cement and water occurs more quickly than normal, resulting in a faster hardening and setting time for the concrete. This can be achieved through the use of various accelerators or admixtures, which are added to the concrete mix to speed up the hydration process.
Accelerated hydration can have several advantages in the production of concrete. By reducing the setting time, it allows for faster construction and reduces the time required for formwork and scaffolding. It can also improve the early strength of the concrete, which is important in situations where the concrete needs to support heavy loads or resist structural stresses. Accelerated hydration can also improve the workability of the concrete, making it easier to place and finish.
Some of the most common accelerators used in concrete production include calcium chloride, triethanolamine, and sodium silicate. These accelerators work by increasing the solubility of calcium and aluminum ions in the cement, which speeds up the chemical reaction with water.
For example, calcium chloride is a widely used accelerator that is added to the concrete mix in small quantities. It can reduce the setting time of the concrete by as much as half, allowing for faster construction and reduced costs. However, excessive use of calcium chloride can cause corrosion of reinforcement steel and other metal components in the concrete, so it must be used in controlled amounts.
Other types of accelerators include water-reducing agents, which reduce the water content in the concrete mix and improve its workability. These agents can also speed up the hydration process by increasing the concentration of cement in the mix.
While accelerated hydration can offer several advantages, it’s important to note that it can also have some disadvantages. For example, it can lead to increased heat generation during the hydration process, which can cause thermal cracking and other types of damage to the concrete. It can also reduce the long-term strength and durability of the concrete if not used correctly.
Overall, accelerated hydration is an important aspect of concrete production, and the use of appropriate accelerators and admixtures can help to improve the workability, setting time, and strength of the concrete, while minimizing its potential drawbacks.