Plaster
Defination: A wet substance that hardens when it becomes dry and that is used to make smooth walls and ceilings.it is also known as soft mixtuer of sand and cement and sometime lime with water for spreading wall celling or other structure to form a smooth hard surface when dried. Similarly , plastering are done both in inside and outside wall.
Objectives:
1.To improve the apperances of the surface by provding an even ,smooth ,regular,clean and finished surface.
2.To preserve and protect the surface from atmospheric influences by acting as a protective coating for the external plastering.
Uses:
Objectives:
1.To improve the apperances of the surface by provding an even ,smooth ,regular,clean and finished surface.
2.To preserve and protect the surface from atmospheric influences by acting as a protective coating for the external plastering.
Uses:
- It is a buliding material used for the protective or decorative coating of wall and celling.
- It is also used for moulding and casting decorative element.
- The most common type of plaster mainly contain either gypsum,lime,cement etc but all work in same way
Type of plaster:
There are two type of plastering materials :
1. Exterior plastering:
This plaster is of three types :
- Stucco plaster finishing: It is widely used in exterior treatment of wall. Stucco is a general term applied to all types of exterior plastering whether it is lime or cement.there are four composite of stucco: - Common stucco -Rough stucco -Trowelled stucco -Bastard stucco
- Rough cast plaster finishing: -It is a type of coarse finishing where cement,pebbles,shells,sand are mixed together with water and then thrown at a wall with a trowel. - The idea is to cover the wall evenly with the mixture for a rough but finished look.
- Modern stucco: -It is a exterior cement plastering with a mixture of cement, lime,sand and water in a proper proportion and additives are put into the mixture for more flexibility. - There are also synthetic stuccos that are out in the market and called by different name and types but they are basically cement based stucco plastering. - There are three essential coats for cement based plastering: The scratch coat The brown coat The final coat 2. 2. Interior plastering: It is different from exterior plastering. There are two types of plastering used for it .
- Dry wall plastering: -It is form of sheet rock that is somewhat greenish in colour. -It is a method of constructing interior walls by making used of gypsum board. -In between the edges of drywall sheets are seams and these seams are covered with mesh tape after which the screws and the seams are covered with drywall plaster to conceal them for finished look .
- Veneer plastering: -It is different from drywall. Instead of covering the seams, the whole wall is plastered with a thin very workable compound . The surface could be ply board ,drywall or cement. - The inner wall material does not really matter as the veneer plastering will cover it anywhere. -It can be smooth, textured or sponged. There are four types of plaster:
- Gypsum plaster: Gypsum plaster, or plaster of Paris, is produced by heating gypsum to about 300 °F. When the dry plaster powder is mixed with water, it re-forms into gypsum. The setting of unmodified plaster starts about 10 minutes after mixing and is complete in about 45 minutes; but not fully set for 72 hours. Plasterers often use gypsum to simulate the appearance of surfaces of wood, stone, or metal, on movie and theatrical sets for example. Nowadays, theatrical plasterers often use expanded polystyrene, although the job title remains unchanged.
- Lime plaster: Lime plaster is a mixture of calcium hydroxide and sand (or other inert fillers). Carbon dioxide in the atmosphere causes the plaster to set by transforming the calcium hydroxide into calcium carbonate (limestone). Whitewash is based on the same chemistry. Lime plaster was a common building material for wall surfaces in a process known as lath and plaster, whereby a series of wooden strips on a studwork frame was covered with a semi-dry plaster that hardened into a surface. The plaster used in most lath and plaster construction was mainly lime plaster, with a cure time of about a month. To stabilize the lime plaster during curing, small amounts of plaster of Paris were incorporated into the mix. Because plaster of Paris sets quickly, "retardants" were used to slow setting time enough to allow workers to mix large working quantities of lime putty plaster.
- Cement plaster: It is a mixture of suitable plaster, sand, portland cement and water which is normally applied to masonry interiors and exteriors to achieve a smooth surface. Interior surfaces sometimes receive a final layer of gypsum plaster. Walls constructed with stock bricks are normally plastered while face brick walls are not plastered. Various cement-based plasters are also used as proprietary spray fireproofing products. These usually use vermiculite as lightweight aggregate. Heavy versions of such plasters are also in use for exterior fireproofing, to protect LPG vessels, pipe bridges and vessel skirts.
- Heat resistant plaster:Heat resistant plaster is a building material used for coating walls and chimney breasts. Its purpose is to replace conventional gypsum plasters in cases where the temperature can get too high for gypsum plaster to stay on the wall. Heat resistant plaster should be used in cases where the wall is likely to exceed temperatures of 50 °C Advantages and disadvantages of plaster :
Advantages of plaster-
-It expands very slightly on setting.
-It is not likely to cause cracking of surfaces.
-It forms a thick surface to resist normal knocks
after drying.
-It is easy to spread and level.It mixes
up easily with water.
-It has no appreciable chemical action on paint and
does not cause alkali attack.
-Tiles and blocks of plaster of Paris have
the specific advantage of lightness and high fire resistance.
-Plaster of Paris gives a decorative interior finish.
Disadvantages
of plaster-
Gypsum plaster is not suitable
for exterior finish as it can not be used indamp finish.
-Cement can not be mixed with plaster
of Paris.
-It is more expensive than cement or cement lime plaster. -It cannot be use in moist situations.The
labor cost for applying plaster of Paris is high.
Observation for cement:
cost of one bora cement of opc= Rs 895
cost of per kg cement of opc= Rs 18
cost of one bora cement of ppc= Rs790
cost of per kg cement of ppc= Rs16
Brand of cement:
Buddha,Shivam,Jagdamba, Ardhakhachi ,Gauthali,Hetauda.
among them Hetauda cement is the expensive one
Kanish Plasters is India’s trusted gypsum plastering company and has a strong foothold in all major cities. We help builders save on construction time and cost, and are revolutionizing the Indian construction industry. Gypsum Plastering has faster setting time than cement sand plastering. The gypsum walls are paint ready in 4 days compared to 15 days with cement sand plastering. Sand cement plastering needs at least 15 days to reach the inherent properties, whereas gypsum gains its inherent properties within 48 days of application. Gypsum wall plaster gain their total strength within 78 hours.
ReplyDelete