Preparation of Lime Mortar

Ordinary lime mortar and plaster are made by grinding lime with sand. There are three methods of preparing lime mortar.

In the first method, a dry mixture of lime and sand are placed in a trough or on a platform in the specified proportion. The required quantity of water is sprinkled over the mixture in stages and mixed each time after the water is sprinkled. Then the mixture is ground to a plastic mixture by pounding with heavy wooden hammers.

The second method is adopted when a large quantity of mortar is needed. A circular annular trough is made and the mixture is placed into it. The mixture is ground by rotating a wheel through the trough with the help of bullocks. This type of mortar production is called a bullock-driven mortar mill. The mixture is ground for about 200 revolutions to get a suitable mortar.

The third method is the modern method, which is used for preparing large quantities of lime mortar. Here, a machine-driven pug or mortar mill is used. For brickwork, the grinding is done for three minutes and longer for plaster for plasterwork, pointing and terrace works. While the construction work is in progress, the mortar is raked up continuously.

Ordinary lime mortar can be stored for a maximum period of 3 days after mixing. Hydraulic lime should be used within 2–4 hours after grinding. The lime mortar should be kept moist by covering it with a wet sack cloth and frequently moistened.