The lime cycle is one of the most important processes still used in modern construction when producing modern cement, yet is one of  the oldest chemical processes known. Today it is used in large scale cement production, whilst the Romans used it in large scale lime production.

The first process is 'calcination of limestone', this is achieved by heating the raw limestone to high temperatures. The limestone is broken into smaller chunks and placed in a rotary kiln where it is then subjected to temperatures ranging  between 750 degs Celcius and 900 degs Celcius which removes all the moisture and CO² from the

The quicklime is highly reactive. Some of it is used directly in concrete building blocks production!, and of course 40 to 60% of what we today call cement is actually limestone (with additives) most of it is slaked ("it's thirst is quenched.") In this  'Slaking' process a highly exothermic reaction occurs which gives off  a tremendous amount of 

Hydrated lime is sold at builders merchants and generally today only used  to provide some flexibility to cement based bricklaying mortar mixes and for repointing (note: this is a common trick used by some builders today claiming to work with lime! Traditional full lime mortars set by re-absorbing CO² from the atmospkere, non scrupulous builders like money in their banks faster, which the cement gives them because it by-passes nature  (plus of course, also by-assing the benefits that nature provides to your home)

In modern construction, cement is used in the mortar to speed up the setting time of the mortar, because in today's world of Now! The natural processes of  evaporation and carbonisation are regarded by many as being 'too slow', we see this as people having become too greedy, too impatient and also having lost respect for nature, which is a real shame.