Types of cracks in plastering walls and their causes,types of cracks in plastering walls,in this article you know about common defects in plaster and what causes cracking in plaster walls and different types of cracks in plaster walls.
many of people thought that we have bought good cement and sand and have done good masonry work and plaster by best masons and labour and provided good proportion of cement mortar but what is the reason crack visible in plastering work and we discus about types of cracks in plastering
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Many of people get confused to getting right answer. In this article we explain different types of cracks visible in plaster and what is their cause and how we will repair it.
Types of cracks in plastering
There are 7 most visible common defect in plaster wall and types of crack in plastering are following:-
1) non structural cracks
2) structural cracks
4) lack of hardness
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● Types of cracks in plaster walls
1) Non-structural cracks :- non structural cracks are those cracks which is usually very fine and Shallow and do not extend through the whole depth of plaster. There is two types of non structural cracks
B) Map cracking
A ) ( i) definition of crazing :- crazing is network of fine cracks and it has hexagonal pattern and their size ranging between 5mm to 75mm across each hexagon and there is only have very fine and Shallow and do not extend through the whole depth of plastering wall.
ii) cause of crazing :- crazing is caused due to result of of providing of rich mix having high amount of cement present in cement mortar and by using sand containing excessive amount of dust material.
iii) repair of crazing cracks:- Craze cracks are occurs within few hours of plastering work and may be hardly be visible until dust or water make them noticeable. Craze cracks have no importance and they do not open and close with later time and can be covered by using reasonable quality of paint and if it is necessary so glass fibre tissue can be applied during the painting operation.
(B) i) definition of map cracking :- map crack is similar like crazing crack except that it is usually deeper and going through the Plaster and the hexagons of pattern may extend upto 200mm size.
ii) cause of map cracking :- these cracks normally occurs when plaster mix with high quantity of cement and that plaster is allowed to dry to quickly and it is due to excessive moisture early loss. Evaporation will occur if the Plaster wall is not protected from the sun and the wind and also caused due to use of badly graded sand and high obsorvable bricks which are not dampened properly.
iii) repair of map cracking :- it should be covered with painting operation and by applying glass fibre tissue.
Note :- 1) plastic shrinkage cracking :- the cracking those are present when an excessive amount of water is lost from the Plaster in the first hours after application is known as plastic shrinkage cracking.
The map cracking can be due to plastic shrinkage can be horizontal cracks which forms at corner and between Windows.
2) drying shrinkage cracks :- it is due to moisture loss after plaster has hardened and plaster will always shrink and Crack. It is always due to very high cement content and those cement mortar which are made of poor quality of sand having high water requirement and this type of cracks are normally stable and can be filled with property filler and painted over.
2) structural cracks :- those cracks which are visible in plaster result from cracking of wall is known as structural cracks. This can be caused by differential movement of the foundation ,moisture expansion, drying shrinkage of brick wall and thermal movement of the roof slab and this type of cracks often forms in straight vertical line or horizontal line or in steeped diagonal lines.
Because these cracks originate in the wall and not in plaster so repairing of plaster wall is ineffective. So greater remedial measures should be recommended with specialist to establish them
3) Debonding :- debonding of plaster is often noticed as a hollow sound when the surface is tapped. In this process plaster is debond from the wall. Because the outside layer of plaster that is exposed to the air will shrink at different rate from the Plaster which are in contact with the wall. It is mainly caused due to thick layer of plaster
4) lack of hardness :- by providing poor quality of cement mortar will have lack of hardness that have insufficient amount of cement and uses more amount of sand containing dust and by mixing poor quality of water and addition of extra water after first mixing and Rapid drying in full Sun causes lack of hardness and cracks in plastering work.
5) Grinning :- greening is the term given to the appearance of plaster wall when the position of mortar joints are clearly visible through the Plaster. It is mainly caused due to difference in suction capacity between the brick walls and the cement mortar
6) Expansion :- expansion are noticeable and this includes swelling,softening,layer cracking and spalling of the Plaster.
It is mainly caused due to gypsum based product in the mix. Under moist condition the sulphate from the gypsum react with the Portland cement paste and forms compound of increased volume which disrupt the Plaster.
7) Popping :- the conical fragments that break out of the surface of plaster leaving the holes which are vary in size are termed as popping. It is mainly caused by the presence of contaminant particles in the mix which reacting with the moisture in the mix expand and cause cavity in the Plaster.
Contaminant particles are usually seeds other organic materials particles of Dead burnt lime and the cause of popping has been removed the hole can be filled with filler and painted cover
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causes of cracks in plaster walls
Main causes of cracks in plaster wall is following:-
1) use of poor quality of cement which is more gypsum based causes swelling, softning of plater wall which causes crack
2) use of badly graded sand that have flaky shaped is not ideal, so we can must use angular roughly cubical graded sand.
3) by use of poor quality of water and excessive amount of water causes bad quality of mortar mix which leads to cracking of plastering.
4) by using contaminant particles in mortar mix causes poor bonding between brick wall and plaster material which leads to cracking of plaster
5) by using a rich mix having high content of cement in cement mortar which is shrinkage after drying process leads to cracking of plaster
6) by providing thick layer of plastering material to the brick wall causes weaker Bond between brick wall and plaster leads to debonding and causes cracking in plaster