Cement Lime Plastering

Combination mortars, consisting of cement, lime and sand are proving to be economical and effective in plastering mud walls. The recommended mortar proportions are as under : 

1. 1 cement : 2 hydrated lime : 9 sand for plastering the interior surfaces of walls, 
2. 1 cement : 1 lime: 6 sand for plastering of exterior surfaces of walls. 

It has already been stated that the plaster must be non-erodable and water-proof; and combination mortars, as listed above, are ideally suited for improving the durability of mud walls. 

While lime-plastered finishes are not suitable for external surfaces in heavy rainfall areas. At damp places and places where water tightness is required, cement-lime plaster is to be preferred. 

Lime and sand are first mixed for the entire day's requirement, and made into a stiff paste and kept in stock. Cement should then be mixed with the mortar batches, and used within two hours of addition of cement. Combination mortars are more workable than cement mortar and hence, they are preferred by masons. 

Precautions 

Surface coatings applied to poorly prepared wall will soon peal off. Certain precautions are essential for the success of the process. The wall must be completely dry before combination mortar is applied as plaster. Surface dust and loose particles should be removed by a coir-brush or broom. The wall should be slightly wetted at the time of actual application of the plaster. Long and narrow grooves at 15 to 20 cm spacing will improve the bonding of the plaster to the wall.