COMPARISON BETWEEN GYPSUM PLASTER AND CEMENT-SAND PLASTER

Plaster is very necessary thing in construction to achieve an aesthetic appearance. Plastering work is a process of covering the rough surfaces or unfinished surfaces like walls, ceilings, column and other building components with thin coat of cement mortar or other material to form a smooth and finished surface and gives an aesthetic appearance. It increases the durability of surface.

Gypsum is one of the widely used construction material mainly in interior designing. Properties and products of gypsum to be used as building material in construction works are discussed. Gypsum is used as surface materials. Its application is prominent in wall and ceiling construction. The use of gypsum can also be done at the field in the form of plaster.

Comparison between Gypsum plaster and Cement-sand plaster

1. Basic Raw Material

  • Gypsum plaster
Gypsum powder and water
  • Cement-sand plaster
 Cement + sand + water (Site mixed)

2. Applicable area
  • Gypsum plaster
It can be use only on internal walls and ceilings. It cannot be used in directly water affected areas like a toilet, bath, kitchen, wash area, etc. Hence, It is for internal use only.
  • Cement-sand plaster
It can be use on both surfaces internal wall as well as external surface. It is not affected by any weather conditions.

3. Thickness
  • Gypsum plaster
Generally the thickness of this plaster is 8 mm for walls and ceilings. However it depends on surface quality.
  • Cement-sand plaster
The thickness of cement plaster should not be less than 10 mm. The Thickness of cement plaster may vary and it depends on the surfaces to be covered.

4. Standard packing size 
  • Gypsum plaster
Gypsum bag is available in market as 25 kg bag. It would be available in different brands.
  • Cement-sand plaster
Cement bag is available in market as 50 kg bag and sand as per tonne.

5. Curing period

  • Gypsum Plaster
Gypsum plaster requires no water curing and should be permitted to dry out as quickly as possible.
Gypsum plaster requires no curing which saves up on all that water and electricity to pump a water.
  • Cement-sand Plaster
Pre-Curing and Post-Curing are necessary for cement sand plaster. Cement plaster needs an enormous amount of water during its curing period. The site becomes dirty due to it and also needs more time for works.

6. Compressive strength

  • Gypsum plaster
Compressive strength of gypsum plaster is 5-7 mpa.
  • Cement-sand plaster
Compressive strength of Cement-sand plaster is vary as per different proportion. But as per standard proportion 1:4 , It achieves 6 - 7.5 mpa.

7. Area covarage (12 mm Thickness considered)

  • Gypsum plaster
1 bag Gypsum 25kg cover 20 sqft area
  • Cement-sand plaster
1 bag cement 50kg cover 90 sqft area

8. Surface finish

  • Gypsum plaster
Gypsum plaster provides a smooth interior finish for ceiling, walls and is ideal back ground for good quality paints and wallpaper finishes.
  • Cement-sand plaster
After cement-sand plaster, POP punning or putty work is required for the better and leveled surface finish.

9. Setting time


  • Gypsum Plaster
Its setting time is very quick. It can be achieve hard surface in 15 to 20 minutes after proper mixing.
  • Cement-sand Plaster
It requires 10 hours to achieve hardness.

10. Shrinkage behavior

  • Gypsum plaster

Gypsum plaster does not shrink as it undergoes very little expansion and contraction.

  • Cement-sand plaster

Cement plaster has the tendency to shrink, which results in hairline cracks on the plastered surface.


Pros and cons of Gypsum plaster

Pros

  • Gypsum plaster gives the walls and ceilings a smooth, level surface that is ready to receive paint. Hence, it reduces POP punning costs which have to be incurred for cement plastered surfaces.
  • The gypsum plaster paste is very easy to work with and prepare, in comparison to cement plaster.
  • Gypsum plaster does not shrink as it undergoes very little expansion and contraction.
  • Gypsum is a green product because it can be recycled an infinite number of times. Made from natural gypsum rock, it is dehydrated to produce a plaster powder. Adding water produces gypsum plaster. This plaster can be salvaged and again converted to powder plaster for re-use.
  • The biggest advantage of going with gypsum plaster is that it dries very fast – within a span of 12 hours. However, the wall or ceiling surface should be painted only 72 hours after application.
  • Due to gypsum’s low thermal conductivity, it keeps your house warm during the cold months and cool during the warm summer.
  • Gypsum plaster has great resistance to fire.
  • It does not require huge space to store material in compare to Cement-sand plaster.


Cons


  • The disadvantage of gypsum plaster is that it can only be used in the interiors of the building; it is not suitable for external plastering.
  • Gypsum plaster should not be used in moisture-free areas where the wall is not directly affected by water like the bathrooms, kitchens, balconies or damp basements.
  • Gypsum is a superior finish compared to cement plaster. However, it is advisable to go with gypsum plaster for the internal walls and ceilings and use cement plaster for the exteriors of the building.




Pros and cons of Cement-sand plaster

Pros

  • Cement plaster can be used for plastering both the external walls and the internal walls and ceilings of the building.
  • The external cement plaster on the building facade is the first line of defence for the building from wind, rain, and harmful industrial gases and vehicular pollution.
  • Unlike gypsum plaster, cement plaster is resistant to moisture.

Cons

  • The final finish of cement plaster is very rough and grey in colour. Hence, the walls have to be treated with POP punning (plaster of Paris punning) to achieve a smooth finish before the application of wall paint. Punning is the application of thin layers of plaster or mortar on a wall to achieve a smooth and flat finish.
  • Cement plaster has the tendency to shrink, which results in hairline cracks on the plastered surface.
  • The cement-plastered surface needs curing (a chemical reaction that achieves strength) with water for at least seven days. Do note that improperly cured walls develop cracks.



Cost comparison of Gypsum plaster and Cement-sand plaster

Cost of Cement-sand plaster 
  • Let's take a 100 sqft wall
  • Thickness of plaster 15mm
  • Proportion 1:4
The Wet volume required of cement mortar is,
=100 x ((15/25.4)/12)
=4.91 cuft

Dry volume of cement mortar is,
= 4.91 x 1.33
= 6.53 cuft

Sand required = (6.53 x 4) / 5
  •  Sand required = 5.224

Cement  bag required = (6.53 x 1) / 5
                                   = 1.306
One cement bag volume is 1.22
So, 1.306/1.22
  • Cement bag required = 1.07 bag
Cement cost = 1.07 x 300 = 321
Sand cost     = 5.224 x 40 = 209

So, Material cost is 530 / 100 sqft = 5.5 Rs per sqft

Labour cost = 12 Rs per sqft.

Total cost = 5.5 + 12 = 17.5 Rs per sqft

                                                                                             


Cost of Gypsum plaster

Here we take JK Lakshmi Gypsumplast
Bag size = 25 Kg
  • Let's take a 100 sqft wall
  • Thickness of plaster 12 mm
1 bag of Gypsum can cover 20 sqft area. (12 mm thickness considered)

Required Gypsum bag = 100 / 20
                                    = 5 bag required.

Cost of 1 bag Gypsum is 200 Rs.

Material cost = 5 x 200 = 1000 Rs.
Hence, 10 Rs per sqft.

Labour cost of Gypsum plaster for wall = 9 rs per sqft
Labour cost of Gypsum plaster for ceiling = 11 rs per sqft

Total cost = 10 + 10 = 20 Rs per sqft

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