From quicklime, slaked lime and lime putty are prepared as discussed below:
1. Slaked Lime
Quicklime is heaped on a masonry or wooden platform. Then water is gradually sprinkled over it till the lime is slaked and reduced to a powder form. During the sprinkling of water, the heap is turned over and over again. This process is continued till no more water can be added than that required for the lime to convert into a powder form. The slaked lime is then sieved through an I.S sieve of mesh size 3.35 mm, and the residue if any is rejected. The end product is slaked lime.
2. Lime Putty
Sometimes before using lime in mortar, quicklime is converted into a putty form. For this purpose two large tanks are made, one 50 cm deep and the other 80 cm deep. The first tank is constructed as a pucca masonry at a higher level. The lower level tank is constructed at the ground level. The lower tank is made of dry brick masonry with joints filled with sand.
The upper tank is filled to half of its depth with water. Quicklime is added gradually till it fills half the depth of water. Only lime should be added to water and not otherwise. It is then stirred taking care to ensure that lime at no time is exposed to the air. For about 5 minutes the mixture is stirred till the boiling stops and it thickens. More water is added, if needed, and then the products are allowed to flow to the lower tank.
The mixture is then allowed to stand in the lower tank for 72 hours. As the lower tank is made of dry brick masonry with sand joints, water in the slurry is partly absorbed by the ground and partly through the brick joints. Thus, excess water is removed, and lime putty is obtained as a paste. It can be stored for about two weeks if adequately protected from drying.
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