LIME MORTAR

Hydraulic limes and Fat lime both are used for making lime mortar. If fat lime is used sand mixed is generally 2 to 3 times its volume. And if hydraulic lime is used sand mixed is just 2 times the volume of lime. By pounding, Lime is prepared, if quantity needed is small or if the required quantity is more then by grinding.

Pounding: In hard grands, pounding pits are formed. The size of pit is generally 1.80 m long, 0.4 m wide and 0.5 m deep. It is provided having stones or lining of bricks. Sand and Lime dry mixed is placed with required proportion in the pit. Small quantity of water is added at intervals. The mix is pounded having wooden pounders and mortar is turned up and down in each interval. The process is continued until uniform colour and desired consistency achieved.

Grinding: It is the better way of getting good mix. Grinding can be carried out in bullock driven grinding mill or in power driven grinding mill.

Given figure shows a typical bullock driven grinding mill. It consist a circular trench of radius 3 to 4.5 m, 0.3 m wide and 0.4 m deep. At centre a wooden shaft pivoted carries a stone wheel of width only 50 mm to 100 mm less than that of trench. In the trench Bullock drive this wheel for grinding mortar. In the trench the dry mix is placed. Water is added slowly and bullock driven stone wheels grind the mix. A worker turns the mix up and down frequently. This method of preparing mortar requires 6 hours and can produce approximate 1.7 m3 of mortar.

                             Bullock driven grinding mill

Given figure shows a typical power driven grinding mill is used for preparing lime mortar. In a pan of diameter 1.8 to 2.4 m two rollers rotate. With the help of oil engine or electric power either pan or roller is rotated. Required quantity of water is added slowly during mixing.

                     Power driven grinding mill

Lime mortar has good grinding property. For plastering Fat lime mortar is utilized whereas hydraulic lime mortar is used for masonry construction. In olden days this mortar was considered cheap and was normally used in small towns. Although the cumbersome process of preparation and in market easy in availability of cement has almost replaced the use of lime mortar.