What is hydration?
Hydration refers to the chemical reaction that takes place between water and cement. This reaction is what gives the concrete its strength and durability. As long as hydration is taking place the concrete will continually gain strength. If the moisture in concrete is depleted, hydration will cease. This may result in lower than desired strength and durability.
Hydration is the term used to describe the chemical reaction that takes place between cement and water. For 100 pounds of cement, only 25 pounds of water is needed to fully hydrate the cement (0.25 water/cement ratio). This reaction will generate three primary products: CSH paste (Calcium Silicate Hydrate), calcium hydroxide and heat. The paste is the glue or binder that combines the sand and stone into a rock hard mass. (In actuality, a w/c of 0.25 does not usually hydrate all the cement due to evaporation and the sealing off of spaces around each particle of cement. There is usually a small percentage of unhydrated cement particles in concrete of various w/c ratios and ages.
