Gypsum building plasters are used extensively abroad for general building operations and the manufacture of pre-formed gypsum building products like tiles, blocks, plaster board etc, which have the specific advantage of lightness and high fire resistance.
Now as there is boom in the real estate in India, the builders and contractors wants time saving in construction, therefore they choose gypsum plaster due to its superior finish and time saving aspect. Now a days, the construction sector has observe a number of new tendency, technology advancements and improvement across application, all meant at making construction faster and delivering higher performance. Gypsum surface plaster is one type that has drawn the attention on the construction sector and is getting higher popularity these days.
Gypsum is a chalk like material light in weight. It is crystalline combination of calcium sulphate and water. It is available as natural gypsum, which is mined all over the world, and as synthetic by product of major industries such as fossil-fuelled power stations. Gypsum products such as molding, design piece around fan and corner design pieces and many more have been used for past time in the construction field and are the material of choice because of gypsum’s unique properties. Gypsum plaster has very good insulation properties both thermal and acoustic. Gypsum plaster has properties like fire protection, moisture resistance, impact resistance and vapor control.
In general case after the construction of wall either with bricks or with blocks, the wall internal surface is finished with cement sand plaster and white washed or painted as the case may be but this surface remain rough. For getting smooth surface Plaster of Paris i.e. POP is applied on the plaster surface before painting or distempering the wall. In this way two stage process involves which takes lot of time and labor, this form of internal finishing being slowly replaced by a direct single coat application of gypsum plaster. Therefore gypsum plaster is in fact a replacement of two different processes i.e. cement sand plastering & POP pruning.
Application of Gypsum Plaster
The materials used in the two stage finish i.e. plaster and POP are cement, sand, water and POP/ putty, where as in gypsum plaster, gypsum and water is required for plastering. Gypsum is mixed with water and applied on the wall within level strips and finished to a smooth surface with steel trowels/ steel float and ensures line and level leaving no undulation in the surface completely made good. The finished surface should be smooth, true to plane, slopes or curves. After drying the surface should be sand papered to give smooth surface. In this way there is saving in time for curing cement sand plaster and time for leveling coat of POP. Cement should not be mixed with Gypsum plaster.
Advantages of Gypsum Plasters
There are some advantages of gypsum plaster over the cement sand plaster & POP finish as detailed below.
Gypsum plaster light in weight, therefore reduces the load on structure.
More cleanliness on site because it is bag packed product and no curing is required.
- Gypsum plaster is directly applied on brick, block or RCC, no separate finishing product required.
- It requires no curing, therefore ready to paint.
- Gypsum plaster saves time during construction and ensures timely possession of homes/ building.
- Gypsum plaster expands slightly on setting and is not, therefore likely to cause cracking of surface.
- On drying out it forms a sufficient dense surface to resist normal knocks.
- Gypsum plaster is comparatively easy to spread and level.
- Gypsum plasters have no appreciable chemical action on paint.
- Gypsum plaster spread and finished to a minimum thickness increasing carpet area.
- Gypsum plaster is perfectly lined, leveled, sharp corner and smooth surface.
- Saving on electricity used for air conditioning as gypsum has very low thermal conductivity.
- It is more durable and green material.
Disadvantages of Gypsum Plaster
- Gypsum plaster is not suitable for exterior finish, as it can not be used in damp situations.
- Gypsum plaster is more expensive than cement sand plaster but cost disadvantages should be weighed against the advantages and the fact that the labor cost is appreciably greater than that of materials in plastering.
- Cement plaster add structurally strength to the wall but not in case of Gypsum plaster.