Di-calcium silicate (C2S) is a major component in the production of cement. Here are some important points to consider regarding its properties and behavior:

Reacts with water only
- Unlike tri-calcium silicate (C3S), which reacts with both water and calcium sulfate to form gypsum, C2S only reacts with water.
- This reaction is slower than with C3S, but still contributes significantly to the overall hydration process of cement.

Hydrates rapidly
- Although slower than C3S, C2S still hydrates rapidly compared to other components in cement.
- This is due to the presence of calcium ions, which facilitate the formation of calcium-silicate-hydrate (C-S-H) gel.

Generates less heat of hydration
- The hydration of C2S generates less heat than C3S, making it a useful component in controlling the temperature rise of concrete during curing.
- This is important because excessive heat can cause cracking and other damage to the concrete.

Has no resistance to sulfate attack
- One disadvantage of C2S is that it has no resistance to sulfate attack, unlike C3S and some other components in cement.
- Sulfate attack can occur when sulfates in the soil or water react with the components of the concrete, leading to deterioration and cracking.

In summary, C2S is an important component in the production of cement, reacting with water to form C-S-H gel and contributing to the strength and durability of concrete. However, it is important to consider its limitations, such as its lack of resistance to sulfate attack.

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