Rate Analysis of Cement - Sand Plaster | Mortar | Requirement of water ratio |

 Mortar :

                Mortar is Bonding agent which is generally produced by mixing cementing or binding material [like-lime] and mix with fine aggregate. 

Difference between Mortar and Plater are :

               Mortar are used in masonry for joining stones, bricks, blocks etc. and Plasters are used for rendering on the outside and inside of walls.

                However the term mortar is also used loosely to refer to both plasters and mortar. 

    How we select the right material for your building !

                  In Plastering material if we increase the quality then cost (price) increases. And if we reduce quality of plaster then Surface protection is compromised. 

• Plaster should be possible to apply it during any weather.
• Plaster material must be cheaper and economical.
• it should be hard and durable.
• It should possess good workability.      

* Make sure

• we have to select Optimum cement mortar ratio.
• we make sure to use good quality of sand [ silt content should be minimum]
• Me must follow the proper plastering work procedure.
• We must know the requirement of plastering thickness.

  Different ratios of cement mortar:

• 1:3 ~ It is a rich mortar mix. It mainly used at external walls and prone to severe climatic conditions. 
• 1:4 ~ It used at ceiling  and external walls.
• 1:5 ~ Is generally used in internal and some times at external walls too.
• 1:6 ~ Most economical Mortar used in internal plastering 

For Ex: 

            For preparation of rate analysis for a internal plaster [12mm] with cement mortar/ plaster 1:6 for room measuring 5m x 8m floor to floor height. 

- Total area to be covered in internal plaster

   to walls =perimeter of room x height

                =  2 ( 5+3 ) x 3

                = 78 sqm

Area of ceiling = 5 x8 = 40 sqm

so total area of plastering = 78+40 +118 sqm

consider, 12 mm thick cement plaster 1:6 [ratio]

   Calculate, first the volume of mortar from the thickness and surface area. Increase this amount by 20% for filling the depressions joints wastages etc. calculate then the volume of mortar when dry by increasing by 1/3rd volume.

   Volume of mortar = .012 x 118 = 1.416 

Increase by 20% for filling this depression etc 

              = 1.416+ 1.416 x 20/100 = 1.7 cum

Volume of wet mix = 1.7 + 1.7 x 1/3

                                = 2.267 cum

so,  summation of Proportion = 1+6 = 7

   Cement = 2.267 x 1/7 = 0.324 cum

              so, no. of bags  = .324/0.0347

                                      = 8 bags

   sand = 2.267x 6/7 =1.94 cum.

Important Points : 

• Wastage - we should add 20% wastage for joints and impressions filling.
• Sand Bulking = Because of moisture present in the sand.

  Ex. External Plaster :

                 For preparation of rate analysis for a External plaster [18mm] with cement mortar/ plaster 1:4 for room measuring length 20m  floor to floor height = 4m.   

           Area of Plastering 20 x 4 =80 sqm.

 for, First coat [10mm] = area of plastering x Thickness of plastering 

                        = 80 x .01

                        = 0.8 cum

  so volume of second coat [8mm] = area of plastering x thickness of plastering

                                           = 80 x .008

                                           =  0.64 cum.

therefore, first coat mortar get 0.8 cum and second coat get 0.64 cum

for 

      Calculate, first the volume of mortar from the thickness and surface area. Increase this amount by 20% for filling the depressions joints wastages etc. calculate then the volume of mortar when dry by increasing by 1/3rd volume.

           First coat = 0.8 + .8 x 20/100 = .96 cum.

volume of wet mix  = .96+ .96 x1/3

                                = 1.28 cum.

for,

    Second coat = .64 + .64 x 20/100 = .768

Volume of wet mix = .768+.768 x1/3 

                                = 1.024 cum.

  for Cement , Sand

for First coat,

summation of proportion = 1+4 =5 

cement = 1.28 x 1/5 = 0.256 

no. of bags = .256/.0347 = 7.3~ 8 bags

sand = 1.28 x 4/5 = 1.024 cum.

And for second

ratio 1+ 3 = 4

cement = 1.024 x 1/4 = .256.

no. of bags = 8 bags.

sand = 1.024 x 3/4 = 0.77 cum.