A Guide to Cement Plaster (gypsum plaster): a blog about all the facts you need to know about cement plaster.
Cement plaster is a homogenous mixture of Portland cement, fine aggregates, and water. Generally, OPC 43 grade cement is mixed with sand (the fine aggregate) in different proportions; hence, this plaster is also called as the cement-sand plaster. PPC cement can also be used in place of OPC-grade cement for plastering.
The proportion of mix recommended for walls is 1 part of cement and 3 to 4 parts of sand by volume for rough surfaces and 1 part of cement and 5 to 6 parts of sand by volume for smooth surfaces. Water should be added slowly till a plastic consistency is obtained where the material sticks firmly on the wall. The addition of water makes the material weak and reduces its strength.
A Guide to Cement Plaster (gypsum plaster): a blog about all the facts you need to know about cement plaster.
Cement plaster is a homogenous mixture of Portland cement, sand and water. It can be applied directly to brick masonry, concrete surfaces, brick tiles and blocks made up of clay, fly ash etc.
The surface of the wall or ceiling on which cement plaster is to be applied should be cleaned with wire brush or scrapper so that it becomes thoroughly clean and free from any loose particles in order to achieve good bonding. Even chipping of old paint or whitewash should be done wherever necessary.
For applying cement plaster on uneven surfaces, a layer of lime mortar (1:3) may be applied before applying cement mortar as per requirement. While applying cement plaster on brickwork or concrete surface, the latter should be allowed to harden for at least 7 days before commencing the work.
Cement plaster (stucco) applied on masonry surfaces is a popular finish material that has been used for many years in the construction of buildings. The basic ingredients for cement plaster are a portland cement based plaster and sand that is mixed with water to form a workable paste. The sand aggregate is usually mixed in the ratio of approximately three parts sand to one part cement by volume. Since this mixture tends to shrink when drying, it must be applied in layers so as not to exceed the shrinkage capacity of the material. Each layer is allowed to harden before the next layer is applied.
In order to accelerate the setting time of cement plaster, some manufacturers add lime and gypsum, which also act as bonding agents. One way of measuring their effectiveness is by testing the setting time after mixing with water. Plaster that is mixed with these additions will set within 15 minutes and will be hard enough to receive another application within an hour after application.
There are two types of cement plasters, namely, one coat (also known as brown coat) and two coat or finish coat. One-coat cement plaster can be applied directly on masonry or concrete surfaces whereas two-coat cement plaster needs one-coat application before it can be applied as finish coat
Cement plaster is a homogenous mixture of Portland cement, fine aggregates, and water. Generally, OPC 43 grade cement is mixed with sand (the fine aggregate) in different proportions; hence, this plaster is also called as the cement-sand plaster. PPC cement can also be used in place of OPC 43 grade if the plastering is done in areas where the sulphate attack is prominent or if there is a high concentration of ground salts in the atmosphere.
Cement plaster is usually applied in a single coat or double coat. In general, thickness provided for single coat cement plaster varies from 12 mm to 15 mm whereas for the double coat plaster, it may vary from 15 mm to 20 mm. The thickness of the layers depends on the shape and size of the wall which further depends on the type of masonry units used in construction. For example, for solid blocks/bricks (9 inches x 4 inches x 3 inches), the thickness of one coat should not be less than 10 mm, however, for hollow blocks (4 inches x 8 inches x 16 inches), it should not be less than 15 mm.
Cement plaster is a homogenous mixture of Portland cement, fine aggregates, and water. Generally, OPC 43 grade cement is mixed with sand (the fine aggregate) in different proportions; hence, this plaster is also called as the cement-sand plaster. PPC cement can also be used in place of OPC 43 grade if specified by the Engineer. The thickness of application for cement plaster varies from 12 mm to 20 mm.
Cement plaster is usually applied in a single coat or double coat. In case of double coat work, the first coat should be allowed to harden before applying the second coat. While applying the second coat, it should be ensured that there are no voids between the first coat and second coats to get a uniform finish without any defects like honeycombing.
Cement plaster is normally removed when its surface starts cracking, flaking, pitting or erosion due to carbonation of its surface. It may also be removed if its surface exhibits efflorescence (due to the evaporation of soluble salts).
Cement plaster is usually applied in a thickness of 15 mm (1:3) or 20 mm (1:4) on brickwork and block work. The cement plaster should be 1:4 ratio cement and sand mixed with water.
For internal and external wall plastering the ratio of cement and sand mixed with water varies from 1:3 to 1:5 depending upon the nature of work, quality of bricks, stones, surface finish and type of finish required. The mortar or the cement sand mix should not be too wet or too dry. It should be just right to stick well to the surface applied.
Cement plaster is a homogenous mixture of Portland cement, fine aggregates, and water. Generally, OPC 43 grade cement is mixed with sand (the fine aggregate) in different proportions; hence, this plaster is also called as the cement-sand plaster. PPC cement can also be used in plastering, but OPC 43 grade is most commonly used cement for plastering. It is manufactured by adding water to the powdery mixture of cement and sand.