Batch with hot or cold water?

The temperature of the water used in batching concrete can have an impact on the properties and performance of the concrete mix. Here are some key differences between batching concrete with hot water vs. cold water:

1. Setting time: Hot water can accelerate the setting time of concrete, which means that the mix will begin to harden and set more quickly. This can be beneficial in colder weather conditions where faster setting time is desirable to prevent the concrete from freezing before it sets.

2. Strength: Using hot water can increase the early strength of concrete, but can reduce the long-term strength. This is because hot water accelerates the chemical reaction between the cement and water, resulting in more rapid hydration and setting. This can lead to a reduction in the overall strength of the concrete in the long run.

3. Workability: The temperature of the water can also affect the workability of the concrete. Hot water can make the concrete more fluid and easier to work with, but can also cause it to lose workability more quickly, which can make it more difficult to place and finish.

4. Shrinkage: Hot water can cause the concrete to shrink more as it dries, which can result in cracking and other defects.

In summary, the use of hot water can be beneficial in certain situations, such as in cold weather conditions or when faster setting time is desirable. However, it is important to carefully consider the impact of water temperature on the properties and performance of the concrete, and to adjust the mix design accordingly. It is also important to use water that is not too hot, as this can have negative effects on the overall quality of the concrete.