Defects in plastering work can be reduced by following the techniques given below.
- Brick and plastering should be done with the finest workmanship by skilled masons.
- The bond of the brickwork must be properly maintained.
- Rubbing brushes on the damaged surface removes puffiness. A solution of one part hydrochloric acid or sulfuric acid and five parts of clean water is prepared and applied to the affected area with the help of a brush. Then the surface is washed with clean water. However, it should be remembered that it is desirable to stop the pupil than to fix it. The construction material should be selected of superior quality and suitable methods of construction should be employed.
- Water should not be used to wash the surface to remove the efflorescence. In that case, the soluble salts will be partially carried inside the surface and flowering will appear again. For this purpose, the deposit is removed from the surface as it appears and the surface is kept under observation for a further period of a few days. After curing, if bloom appears again, it is removed with a dry brush and the process is repeated until all soluble salts are removed under normal drying conditions. It is advisable to postpone painting until the mannequin is finished.
- Bricks of superior nature should be used only for brick work.
- Salt free water should be used for brick work and plastering work.
- The surface to be plastered should be well watered so that it does not absorb water from the plaster.
- Excessive troweling should be avoided.
- Damp-proof courses should be provided at convenient locations in the building.
- The overall construction should be such as to prevent the penetration of moisture.
- Freshly plastered surfaces should be protected from excessive amounts of water such as rain and extreme heat such as the sun.
- The surface of the concrete which is usually flat and smooth, should be hacked so as to create a kay when the concrete turns green i.e. the shutter is removed. However, this point is generally neglected and plastering is done on surfaces in haste or with minor hacking. This will lead to peeling at a later stage.
- If the surface is not hacked properly, there are two options to make the surface rough:
- Clean the surface with water to keep the surface wet and perform an acid treatment with 1 part muriatic acid diluted in 10 to 20 parts water applied to the surface. More than one coat may be necessary. After this treatment the wall should be rinsed with water to remove all traces of acid.
- Sometimes, some surfaces can’t even be roughened with acid and a better way would be a splatter dash key,
What is splatter dash?
It simply means a rich mixture of Portland cement and coarse sand that is thrown over the background by a trowel, scoop, or other tool to form a thin, coarse-textured continuous coating. As a preliminary treatment, prior to rendering, it helps to connect the undercoat to the background, improve resistance to rain penetration, and also exclude variable background suction.
In this method a mixture of coarse sand (8 mm and below) mixed in cement in the ratio of 1:1.5 and water equal to 0.5 part of the total volume is lashed unevenly on the wall. Where fine sand is difficult to obtain, crushed hard stone (removing fine particles) can also be used.
The amount of water will vary with the type of aggregate. The dry ingredients should be mixed well and then water should be added gradually. The mixture must be stirred continuously during use.
The splatter dash does not need to cover every piece of surfaces and is an advantage if parts of the surface are not covered. The main objective is to create a large number of small humps of mortar in order to make the surface as irregular as possible. The thickness of the splatter dash can be limited to 10 mm. With good cure allowed 2 to 3 days; Further work can be done. Of all the methods of providing the key, the spatter dash method should be preferred in practically all cases.
- In brickwork, racking of joints on the finished side should be done as soon as the day’s brickwork is finished to provide effective keys to hold the plaster.
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