What kind of reaction is hydration in concrete?

Hydration in concrete is an exothermic reaction, meaning it releases heat. When water is added to cement, a series of chemical reactions occur, leading to the formation of various compounds that contribute to the strength and durability of the concrete. This process not only results in the hardening of the mix but also releases energy in the form of heat.

The heat generated is particularly important as it can influence the curing process, ensuring that the concrete sets properly and achieves its intended strength. This is why, in large pours, managing the temperature and hydration process becomes crucial to avoid issues like thermal cracking.

In contrast, the other types of reactions mentioned, such as endothermic, involve the absorption of heat from the surroundings, which does not apply to the hydration of cement. A neutral reaction would not involve any significant change in temperature, and light-producing reactions, while interesting, are not characteristic of the hydration process in concrete. Thus, hydration's nature as an exothermic reaction is central to understanding the behavior of concrete during its hardening phase.