Define cement plaster
It is a method use for the finishing of any concrete, brickwork etc. It is done by the method of mortar consisting of cement, sand, and water in a proper ratio as described in the BOQ or Finishing Drawing. In this you generally have to deal with two ratios for example if anyone say or in drawing its mention that you have to plaster in 1:4 Ratio. That means one part of cement and four parts of sand.
Methods of cement plaster| Procedure of cement plaster
Following are the points mentioned below you have to use for Methods of cement plaster-
Preparation of surface for plaster-
1. The surface to be plastered shall be washed with fresh clean water free from all dirt, loose material grease etc. and thoroughly wetted for 6 hours before plastering work is commenced. Concrete surfaces to be plastered will however be kept dry.
2. The wall should not be too wet but only damp at the time of plastering the damping shall be uniform to get uniform bond between the plaster and the wall. The junction between the brickwork and RCC should be fixed with chicken wire mesh/PVC strip as directed before plaster, including hacking of concrete surface after deshuttering of RCC work.
Cement plasters mix| mixing of Mortor for cement plaster
The proportion of the mortar shall be as specified under the respective items of work. Cement shall be mixed thoroughly in dry condition and then just enough water added to obtain a workable consistency. The quality of water, sand and cement shall be as mentioned in the Specifications for Concrete & allied works.
The mortar thus mixed shall be used immediately and in no case shall the mortar be allowed to stand for more than 30 minutes after mixing with water. The plaster shall be laid in a single coat. The mortar shall be splashed on the prepared surface with a trowel and finished smooth by trowelling.
The plastered surface shall be rubbed with iron plate till the surface shows cement paste. The work shall be smooth /plain finished in required line, level and plumb including cutting and providing grooves of 20mm x6mm or as per the details.
Curing of cement Plaster
Curing of plaster shall be started as soon as the applied plaster has hardened enough so as not to be damaged. Curing shall be done by continuously applying water in a fine spray and shall be carried out for at least 7 days.
Important points for cement plaster
The plaster shall be carried out on jambs, lintel and cill faces top and undersides, including making pattas, bends, grooves etc. as shown in the drawing. No holes for scaffolding will be permitted into the brickwork.
How to Make Plaster Measurement for Billing
Rules for deduction in plastering
i) No deductions shall be made for opening or end steel joints, beams, post girders etc. up to 0.5 SqM area. No addition shall be made for joints, soffits and sills of such openings. This is applicable to both the sides of the wall.
ii) Where opening exceeds 0.5 SqM but does not exceed 3 SqM and also when only one side of the wall is treated and other side is not treated, deduction shall be made if the width of the reveal on the treated sides is less than that on the untreated side but if the width of the reveal is more then no deduction nor addition shall be made for reveals for jambs, soffits, sills etc.
iii) For openings more than 0.5 SqM but not exceeding 3 SqM and also when both the sides of the wall is plastered with the similar plaster, deduction shall be made for one face only. But when both the sides treated with different plaster, then deduction shall be made from the side on which the reveal is less and no deduction on the other side.
iv) For openings whose respective areas exceed 3 SqM deductions shall be made for the full opening of the wall treatment on both faces while at the same time jambs, sills and soffits shall be measured in sq m for payment. In measuring the jambs deduction shall not be made for the area in contact with the frames of doors, windows etc.
v) If the average thickness of the plaster is more than the specified thickness due to any account nothing extra shall be paid for the same so try to plaster as given in the Boq.
vi) Nothing extra shall be paid for double scaffolding so while filling the rates in Tender, consider these things at the time of calculation of rates.
Mode of Measurement of plaster
Cement plaster is measured in SqM.
Example– We take an example you want to measure the plaster of room of size 3 meter x 4 meter with a height of 3 meter having window of 1.2 meterx1.2 meter and Door of size 1 meter x 2.1 meter with a wall thickness of 230mm.
|Cement PLASTER Measurement|
|1||Two side wall of 3 meter||SQM||2.00||3.00||3.00||18.00|
|2||Two side wall of4 meter||SQM||2.00||4.00||3.00||24.00|
|3||Deduction of window||SQM||-0.50||1.20||1.20||-0.72|
|4||Deduction of Door||SQM||-0.50||1.00||2.00||-1.00|
Note: – In this we deducted, half of the door and window as we calculated only internal wall plaster and as per the rule ii mentioned above any area from .5 sqm to 3 sqmm with both sides plaster one side should be deducted.
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