What Is Lime?

Limestone is a sedimentary mineral which is largely composed of the calcite (calcium  carbonate). When limestone is burnt at a high tempature produces quick lime, a calcium oxide. When water is mixed with the lime, slaked lime is created (calcium hydroxide). Slaked lime was mainly produced as lime putty for building industry using lime kilns. Lime putty is very malleable when first mixed, but after a while it absorbs carbon dioxide from the atmosphere and strengthens the lime, as it reverts back to calcium limestone.

Lime in simple terms, is calcium combined inorganic materials; where carbonates, oxides and hydroxides are the main contributing elements. In layman terms Calcium oxide or calcium hydroxide. It can also be a single mineral (Native lime) of the CaO composition.

Lime mortar is made in a three stage process, which can be seen below.

1) Calcination

2) Hydration                

3) Carbonation                           

CaCO3 + heat

CaO + H2O

Ca(OH)2 + CO2

=        CaO + CO2

=        Ca(OH)2 + Heat

=        CaCO3 + H2O

Lime Kilns

The Romans were supposedly the first to develop the burning of limestone for it to be used in building as a mortar, although there is little evidence of their kilns in the country. In the Middle Ages, a demand for building grew, the ever demand for lime became a priority. Most lime kilns were temporary structures to the building site. After the site was built they either left to collapse or dismantled and moved to the next building project. In some rural places the limestone was simply burnt in clamps or Pye kilns, or burnt in an enclosed heap.

bristol lime kiln

Lime Cycle

The lime cycle is one of nature’s best known examples of chemistry. This lifecycle occurs for both high calcium, lime and Dolomitic lime products.

lime cycle