Lime Mortar

Lime mortar was man's first real good building cement.

Lime must has been discovered soon after man learned how to use fire and then to make fire when ever desired. When using stone for building a place for his fire, man soon learned that not all types of stones should be used for fireplaces. Limestone is one, because it sends out out hot gases and sparks when heated. And if heated hot enough, limestone turns into a white powder. When water is added, the white powder becomes quite hot before cooling into a harden mass.
At some time, two or more rocks became cemented together in the fireplace. Someone then discovered by experimentation that the addition of clean sand reduced the amount of lime required and decreased the hardening time. Those unknown early builders decided to use this process to build a better fireplace or hearth. A permanent one, perhaps with high sturdy walls.
Perhaps from this simple beginning, the art of masonry was born.
The first building mortars developed were then the lime mortars, a slow hardening mixtures of lime, sand, and water.

The development of Portland cement in 1824 allowed the introduction of a hydraulic binder, which was very consistant and set up rapidly. Its relatively rapid development of bonding strength was a marked advantage over lime mortars. This was particularly important in situations where there was a risk of frost. And Portland cement would harden even underwater. Lime mortars can not. Lime mortar set slowly and hardened even more slowly so builders slowly abandoned lime mortar in favor of the cement and sand mortars.
By the 1830's, the 1:1:6 mixture of cement, lime and sand ratio had been firmly established.
However, cement and sand mortars proved too strong for some applications and lacked some of the workabilty of lime mortar. By the late 1800's cement-lime mixes were again widely used where increased plasticity, workability and controlled strength was required. And recently, lime mortars are being widely used again. Lime mortars are especially desired for masonry restoration work on historical mansonry buildings and other structures.

Lime mortar has important characteristics:


Lime is produced from limestone through these following steps.

Reference definitions:

Books On Making and Using Lime Mortars

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This page was last updated Frebrary 18, 2020.