written 4.5 years ago by |
• The mix ratio of mortar in case of cement plastering depends upon the nature of the work to be plastered.
• For rich plastering work at sensitive places (e.g. in side bathrooms, W.C. etc.), 1:3 cement plaster mix is used. For general plastering of walls 1:5 to 1:8 cement plaster mixes are used.
Preparing the surface
• Before applying the plaster, the surface should be prepared properly.
• The joint of masonry are properly raked to a depth of 20 mm to provide key to plaster.
• The surface is then thoroughly wetted with water, washed well and kept wet for six hours.
• When the surface is ready, plaster is applied.
Applying the plaster
• Cement plastering may be applied in one or two coats.
• In case plastering is to be done in two coats the first coat is applied as described below.
• The mortar is dashed against the prepared surface into a uniform thickness with the help of trowel.
• Wooden screeds 7.5 cm wide and of required thickness of the plasters are generally fixed vertically 2.4 to 3 m apart to act as gauges/ guides in order to keep the plaster to the required thickness. Careful plumb line should be done in fixing of these screeds.
• Surplus mortar is removed with the help of mason’s straight edge and then the mortar is pressed well with a wooden float so that mortar may fill in the joints of the masonry.
• The thickness of this coat should not be more than 16 mm.
• Before applying the second coat, the first coat is allowed to set but it should not become dry and it is also roughened with a scratching tool to provide key to the second coat.
• The second coat is then applied in a thin layer not exceeding 3 mm in thickness within 48 hours.
It is then well trowelled and rubbed perfectly smooth with the help of a steel float. It is then allowed to set for 2 days and cured for more than 7 days.