Hydrated lime known also as builders’ lime or slacked lime is calcium hydroxide. It is made by treating burnt lime with water. It is a white crystal or white powder.  It is used mainly in mortar and concrete. It is more expensive than agricultural lime. It is also used as a flocculant, in water and sewage treatment.

The neutralizing value of hydrated lime is 136. That means instead of using 136 gram of lime stone (Calcium carbonate), 100 gram of hydrated lime (Calcium hydroxide) is enough.