Plaster is intended to create a leveling finishing layer on the surface of walls, partitions, ceilings, columns and other building structures. There are different types of plasters used depending on the purpose of the materials used for plastering. The use of plaster in a particular case is also determined by the climatic conditions of construction, fire safety requirements, and the temperature and humidity conditions in which the room is operated. Plaster is also intended to protect building structures from aggressive influences.
Taking these conditions into account, the type of plaster mortar with waterproofing and acoustic properties is determined. When performing decorative plaster, either ready-made compositions are used, or by selecting compositions and pigments using special technologies. Depending on the type of surface to be plastered, various plaster compositions are used. Wet plaster from lime or complex mortars is done on stone, cement on a concrete surface, with preliminary notching of the surface. Wet plaster on wood is made from lime-gypsum mortar with additives. When creating thicker layers of more than 20 mm, as well as when finishing protruding concrete and brick architectural parts with plaster and at joints made of different materials, plastering is performed using a grid. The metal mesh reinforces the plaster and prevents the formation of cracks on it and along the joint line.
Wet plastering is performed by applying a plaster solution to the surface. In comparison with finishing from gypsum plasterboard sheets manufactured in factories, wet plaster has a number of advantages and disadvantages.
Disadvantages of wet plaster consist in the duration and complexity of implementation, the required technological period of drying and the release of a large amount of moisture in the room, which negatively affects the timing of the commissioning of the facility.
Advantages of wet plaster consists of a monolithic connection with the plastered surface, sealing of all cracks in the structure, no gaps are formed between the surface and the plaster, no seams, the ability to give the surface different shapes, operation in wet conditions, high strength, making it indispensable in conditions of possible mechanical impact (basements , utility rooms, rooms with the location of equipment and movement of vehicles in warehouses). Also, wet plaster is universal in its use in various conditions, by selecting different compositions.
Wet plaster is divided into: simple, improved, high quality.
Simple plaster performed in basements, attics, ancillary residential and public buildings, in non-permanent buildings, in temporary buildings, i.e. in non-residential premises where careful surface treatment is not required. Simple plaster is carried out by brushing in two layers - spray and soil, without hanging and checking the rule; the covering layer is not applied, but the surface of the soil is rubbed. The corners of window and door slopes, pilasters, pillars are carefully leveled with a trowel. The total thickness of the plaster coating does not exceed 12mm.
Improved plaster It is done in residential and public buildings (schools, hospitals, kindergartens) in high-class utility rooms, for plastering facades without special architectural design. Improved plaster is carried out by applying a 5mm thick spray on stone, concrete and brick surfaces, one or several layers of soil 5mm thick for cement mortars and 7mm thick for lime mortars, a covering layer 2mm thick with a surface check using the rule. The total thickness of the mantle is on average 15mm. The covering layer is rubbed and smoothed with a special tool.
High quality plaster performed in rooms with high requirements - in theaters, museums, residential apartments. Surfaces with high-quality plaster are strictly vertical and horizontal planes. High-quality plaster is made from a layer of spray, one or several layers of soil and a covering with hanging the surface and installing beacons. The average thickness of high-quality plaster is 20mm.
Permissible quality deviations of surfaces depending on the type of plaster
Deviations
Permissible deviations in the quality of plaster
improved
high quality
Surface irregularities (detected when applying a rule or template 2 m long)
No more than three irregularities with a depth or height of up to 5 mm
No more than two irregularities up to 3 mm
Depth or height up to 2 mm
Deviation of the surface from the vertical
15 mm to room height
2 mm per 1 m height, but not more than 10 mm over the entire height of the room
1 mm per 1 m height, but not more than 5 mm over the entire height of the room
The same, from horizontal
15 mm for the entire room
2 mm per 1 m of length, but not more than 10 mm for the entire length of the room or its part limited by purlins, beams, etc.
1 mm per 1 m of length, but not more than 7 mm for the entire length of the room or its part limited by purlins, beams, etc.
Deviations of husks, usenki, window and door slopes, pilasters, pillars, etc. from vertical and horizontal
10 mm for the entire room
2 mm per 1 m of height or length, but not more than 5 mm for the entire element
1 mm per 1 m of height or length, but not more than 3 mm for the entire element
Deviations of the radius of curved surfaces from the design value (checked with a pattern)
Deviation of the width of the plastered slope from the design
Not checked
1 Deviation of rods from a straight line within the limits between the angles of intersection of rods and braces
The requirements for surfaces intended for plastering must also meet the required quality established by the requirements of SNiP, since if they do not comply with the permissible deviation values, more material will be required, which will lead to an increase in the cost of purchasing materials and the total cost of finishing work at the construction site.
Requirements for surface quality according to SNiP 3.03.01
Deviations of surfaces and angles of masonry walls and pillars from the vertical:
- on one floor - no more than 10 mm;
- for the entire building - no more than 30 mm.
Irregularities in the vertical surface of the masonry, detected when applying a 2m long batten:
- for walls - 10 mm;
- for pillars - 5 mm.
Deviations of the planes of wall panels and partitions from the vertical (in the upper section) for prefabricated reinforced concrete structures ±5 mm:
Deviations of wooden walls and partitions from the vertical per floor:
- frame houses - 10 mm;
- panel houses - 5 mm.
Lumps and sagging on the surfaces of reinforced concrete structures must be cut off and cleaned.
The humidity of brick walls should not exceed 8%. The temperature inside the room near the walls at a height of 50cm from the floor should not be lower than 10°C. Indoor air humidity should be no more than 70%. The room must be insulated from the penetration of cold air.
Technology for high-quality plastering of brick surfaces
1. Introduction
3. Materials
4. Execution technology
5. Quality requirements
7. Safety precautions
1. Introduction
Insulation of a building, protecting it from destruction by precipitation, increased fire resistance - this is perhaps the most important purpose of plastering work. It is best to plaster any building only after it has completely settled.
There can be several types of plaster. They differ in their own ways.
Monolithic is performed using the “wet” method, while the “dry” method is characterized by the work being performed using thin sheathing sheets.
Plaster can vary in quality, purpose and surface treatment. According to these criteria, it can be special, ordinary and decorative.
Ordinary plaster is divided into the following types:
simple plaster;
improved plaster;
high quality plaster.
Plastering work is one of the most important technological processes in construction production, the technical level of which largely determines the quality and durability of construction projects. At the same time, they are one of the most labor-intensive types of work on a construction site. During the construction of various objects, plastering works consume up to 25% of the total labor intensity and amount to about 30% of the total cycle time.
High-quality plaster is intended for leveling the surface for further high-quality painting with various paint compositions or wallpapering.
High-quality plaster is also intended for subsequent covering of surfaces with ceramic tiles. The quality of this plastering is the envy of the quality of subsequent work. Minimum permissible deviations allow subsequent high-quality finishing work to be carried out in the future.
2. Tools and accessories
A plaster trowel (trowel) is used when measuring materials, for mixing and spreading mortar on the surface.
Cutting off) is a small spatula, convenient when performing repair work. Used for cutting mortar and cutting cornices.
Falcon is a light wooden shield with a handle in the middle. It is made from thin boards with dowels or nails. Metal falcons are available for sale
Water level - designed to find points that lie in the same horizontal plane.
Universal level - designed for checking horizontal and vertical walls/ceilings.
Everyone knows the hammer, chisels and brushes. Brushes are used to wet the surface with water before plastering or during grouting of plaster.
Graters) consist of a cloth and a handle, used for spreading and leveling the solution, rubbing husks, grooves or chamfers. The canvas can be of different sizes. For basic work, graters with a blade size of 700 x (100...120) mm and a thickness of 20 mm are usually used.
Floats are used for grouting plaster: They consist of a sheet 140-160 m long, 100-120 wide and 20-25 mm thick with a handle made according to the hand of the worker. The handle is attached with a dowel (wooden or metal rod) or an ordinary nail so that they do not protrude beyond the plane of the blade on the working side of the grater.
The rules are well-planed slats with a square or rectangular cross-section.
They are used to check the flatness of planes and straightness of corner edges.
Modern metal rules also apply.
The half-grater is intended for removing Usenki.
The mortar box is designed for mixing mortar
Scaffolding is designed for working at heights
3. Materials
3.1 Properties of building materials
Building materials differ in physical and mechanical properties.
Physical properties.
Physical properties include the following parameters: density, porosity, water absorption, moisture release, hygroscopicity, water permeability, frost resistance, thermal conductivity, sound absorption, fire resistance, fire resistance and some others.
Density.
The density of the material is average and true. The average density is determined by the ratio of the mass of a body (brick, stone, etc.) to the entire volume it occupies, including the pores and voids present in it, and is expressed in the ratio kg/m2.
True density is the limit of the ratio of mass to volume without taking into account the voids and pores present in them.
For dense materials, such as steel and granite, the average density is almost equal to the true one, for porous materials (brick, etc.) it is less.
Porosity.
This characteristic is determined by the degree of filling the volume of the material with pores, which is calculated as a percentage. Porosity affects such properties of materials as strength, water absorption, thermal conductivity, frost resistance, etc.
Based on the size of the pores, materials are divided into fine-porous, in which the pore sizes are measured in hundredths and thousandths of a millimeter, and large-porous (pore sizes - from tenths of a millimeter to 1-2 mm). The porosity of building materials varies over a wide range. So, for example, for glass and metal it is 0%, for brick the porosity is 25-35%, for mipora it is 98%.
Moisture release.
This property of the material characterizes the ability to lose moisture in its pores. Moisture loss is calculated as the percentage of water that the material loses per day (at a relative humidity of 60% and a temperature of 20 °C).
Moisture loss is of great importance for many materials and products, such as wall panels and blocks, which usually have high humidity during the construction of a building, and under normal conditions dry out due to water loss. The water evaporates until a balance is established between the moisture content of the wall material and the humidity of the surrounding air.
Water absorption.
Water absorption is the ability of a material to absorb and retain moisture in its pores.
By volume, water absorption is always less than 100%, and by weight it can be more than 100% (for example, for thermal insulation materials). Saturation of a material with water worsens its basic properties, increases thermal conductivity and average density, and reduces strength.
The degree of reduction in the strength of a material at its maximum water saturation is called water resistance and is characterized by a softening coefficient.
Materials with a softening coefficient of at least 0.8 are considered waterproof. They are used in structures located in water and in places with high humidity.
Hygroscopicity.
Hygroscopicity is the property of porous materials to absorb moisture from the air. Hygroscopic materials (wood, thermal insulation materials, semi-dry pressed bricks, etc.) can absorb large amounts of water. At the same time, their mass increases, strength decreases, and dimensions change. For some materials, in conditions of high and even normal humidity, it is necessary to use protective coatings. And materials such as dry-pressed bricks can only be used in buildings and rooms with low air humidity.
Water permeability.
Water permeability is the ability of a material to pass water under pressure. This characteristic is determined by the amount of water passing at constant pressure for 1 hour through a material with an area of 1 m2 and a thickness of 1 m. Waterproof materials include especially dense materials (steel, glass, bitumen) and dense materials with closed pores (for example, specially selected concrete composition).
Frost resistance.
Frost resistance is the ability of a material in a water-saturated state to withstand repeated alternating freezing and thawing without reducing strength and weight, as well as without the appearance of cracks, delamination, or crumbling.
For the construction of foundations, walls, roofs and other parts of the building that are subject to alternate freezing and thawing, it is necessary to use materials with increased frost resistance. Dense materials that do not have pores, materials with insignificant open porosity, with water absorption of no more than 0.5% are frost-resistant.
Thermal conductivity.
Thermal conductivity is the property of a material to transfer heat in the presence of a temperature difference between the outside and inside of a building. This characteristic depends on a number of factors: the nature and structure of the material, porosity, humidity, as well as the average temperature at which heat transfer occurs. Crystalline and large-porous materials, as a rule, are more thermally conductive than materials with an amorphous and fine-porous structure. Materials with closed pores have lower thermal conductivity than materials with interconnected pores.
The thermal conductivity of a homogeneous material depends on the average density: the lower the density, the lower the thermal conductivity and vice versa. Wet materials are more thermally conductive than dry materials, since the thermal conductivity of water is 25 times higher than the thermal conductivity of air. The thickness of the walls and ceilings of heated buildings depends on this indicator.
Sound absorption.
Sound absorption is the ability of a material to reduce the intensity of sound as it passes through the material. Sound absorption depends on the structure of the material: interconnected open pores absorb sound better than closed ones. Multilayer walls and partitions with alternating layers of porous and dense materials have the best sound insulation properties.
Fire resistance.
Fire resistance is the ability of materials to withstand high temperatures. According to the degree of fire resistance, materials are divided into fireproof, fire-resistant and combustible. Fireproof materials (brick, concrete, steel) do not ignite, smolder or char when exposed to fire or high temperatures, but can be greatly deformed.
Refractory materials (fiberboard, asphalt concrete) smolder and char, but after the source of fire is removed, these processes stop. Combustible materials (wood, roofing felt, plastics) ignite or smolder and continue to burn or smolder even after the source of fire is removed.
Fire resistance.
Fire resistance is the ability of a material to withstand, without deforming, prolonged exposure to high temperatures. According to the degree of fire resistance, materials are divided into fireproof, withstanding temperatures up to 1580 °C and above (fireclay brick), refractory, withstanding temperatures of 1350-1580 °C (refractory brick), fusible, softening or collapsing at temperatures below 1350 °C (ceramic brick).
Mechanical properties.
The mechanical properties of a material include its strength, elasticity, ductility, brittleness, impact resistance and hardness.
Strength.
Strength is the ability of a material to resist destruction under the influence of external forces that cause internal stress in it.
The strength of a material is characterized by its tensile strength under three types of influence on it - compression, bending and tension.
Elasticity.
Elasticity is the ability of a material, after deformation under the influence of any loads, to return to its original shape and size. The highest stress at which a material still has elasticity is called the elastic limit. Elastic materials include rubber, steel, and wood.
Hardness.
Hardness is the ability of a material to resist the penetration of another, harder body into it. This property of materials is important when constructing floors and road surfaces.
Fragility.
Brittleness is the property of a material to instantly collapse under the influence of external forces without noticeable plastic deformation.
Fragile materials include brick, natural stones, concrete, glass.
Plastic.
Plasticity is the property of a material to change its shape and dimensions under load without the formation of ruptures and cracks and to retain the changed shape and dimensions after removing the load. This property is the opposite of elasticity.
Plastic materials include bitumen, clay dough, etc.
Impact resistance.
Impact resistance is the ability of a material to resist destruction under the influence of impact loads. Fragile materials do not resist shock loads well.
Portland cement.
This is a hydraulic binder, a product of fine grinding of clinker with the addition of gypsum (from 3 to 5%), which regulates the setting time of cement. Based on their composition, there are Portland cement without additives, with mineral additives, Portland slag cement, etc.
The beginning of setting of Portland cement at a water temperature in the solution of 20 °C should occur no earlier than 45 minutes from the moment the solution is prepared and end no later than 10 hours.
If water at a temperature of more than 40 °C is used in the preparation of the solution, setting may occur too quickly.
The strength of Portland cement is characterized by grades 400, 500, 550 and 600. In order to bring Russian standards closer to European ones, cement is divided into classes: 22.5; 32.5; 42.5; 55.5 MPa.
Fast-hardening Portland cement.
This is Portland cement with mineral additives, characterized by increased strength. It reaches more than half of the planned strength after 3 days. hardening.
Rapid-hardening cement is produced in grades 400 and 500.
Extra-fast-hardening high-strength Portland cement
Used in the production of prefabricated reinforced concrete structures and during winter concrete work. They produce 600 stamps.
White Portland cement.
They produce two types - white Portland cement and white Portland cement with mineral additives. According to the degree of whiteness, white cements are divided into 3 grades (in descending order). The beginning of setting of white Portland cement should occur no earlier than 45 minutes, the end - no later than 12 hours after preparing the solution.
Colored Portland cement.
It comes in red, yellow, green, blue, brown and black. It is used for the production of colored concretes and mortars, finishing mixtures and cement paints.
They produce grades 300, 400 and 500.
Portland slag cement.
It consists of blast furnace slag and natural gypsum, added to regulate the setting time of the solution.
Available in grades 300, 400 and 500.
Fast-hardening Portland slag cement.
It is characterized by increased strength after just 3 days of hardening.
They produce 400 stamps.
Gypsum-alumina cement.
It is obtained by mixing high-alumina slag and natural gypsum. The beginning of setting of gypsum-alumina cement should occur no earlier than 10 minutes, the end - no later than 4 hours after preparing the solution.
Lime.
This material is used mainly when working with stone and for preparing plaster mixtures. There are three types of lime: hydraulic, highly hydraulic, air. They differ in the method of hardening. Airborne lime hardens in air. Its main drawback is its non-water resistance.
Hydraulic is capable of hardening in air and water; its hardening process is faster than that of air, and its strength is much higher. Highly hydraulic lime is characterized by high strength and hardening speed.
When purchasing lime, you must pay attention to the presence of instructions for preparing and storing the solution.
Lime is slaked by treating quicklime with water. Depending on the amount of water required for slaking, hydrated lime (fluff), lime dough and lime milk are obtained.
Powdered hydrated lime is obtained if the volume of water is 60-70%. As a result of slaking, the volume of lime increases 2-3 times. Slaked lime is a white powder consisting of tiny particles of calcium oxide hydrate with a density of 400 kg/m 3 (in a loose state) to 500-700 kg/m 3 (in a compacted state).
To obtain lime paste, when slaking, use 3-4 times more water than lime. The volume of the resulting dough is 2-3 times greater than the volume of lime taken for its preparation.
Lime paste is a white plastic mass with a density of up to 1400 kg/m3.
Lime that has been slaked well, having increased in volume by at least 3 times, is called fat, increased in volume by less than 2.5 times - skinny .
According to the ability to harden, it is divided into hydraulic and air. In the first case, lime hardens both in water and in air, and in the second, as the name implies, only in air.
Lime is produced by burning limestone in shaft kilns. After firing, quicklime is obtained - boiling lime, or lump lime. To slak lime, it is poured with water at the rate of 35 liters of water per 10 kg of lime. During the slaking process, the lime begins to “boil”, crumbling into small pieces, after which it noticeably increases in volume. Based on the slaking time, they distinguish between fast-slaking (about 8 minutes), medium-slaking (about 25 minutes) and slow-slaking (more than 30 minutes) lime.
Slaked lime is called fluffy. In order for all lime particles to be extinguished, it must be kept for about 2-3 weeks. under a closed lid.
After the specified period, a finely dispersed mass remains with a water content of no more than 50%.
Air lime It can be quicklime and slaked (hydrated). Lime without additives is divided into 3 grades (1st, 2nd, 3rd), lime with additives - into two (1st, 2nd). Hydrated powdered lime (fluff), with and without additives, comes in two grades (1st, 2nd).
The scope of application of air lime is the preparation of lime-sand and mixed mortars, which are used in masonry and plastering surfaces, as well as for whitewashing and in the production of silicate products.
Hydraulic lime It can be weakly hydraulic or strongly hydraulic. It is used for the preparation of masonry and plaster mortars, as well as low-grade concrete intended for hardening both in air and in conditions of high humidity.
They are divided into lime-slag with the addition of granulated slag, calc-pozzolanic with the addition of sedimentary or volcanic active rocks, and lime-ash with the addition of ashes of certain types of fuel. Lime-containing substances are involved in the preparation of low grades of concrete and mortars that are used in underground structures.
Gypsum binders.
It is obtained by firing and grinding from sedimentary rock, which contains gypsum dihydrate. Gypsum binders have the ability to quickly set and harden. Depending on the temperature of heat treatment of raw materials, two groups of gypsum binders are distinguished: low-burning (molding construction and high-strength gypsum) and high-burning (anhydrite cement, extrich gypsum).
Based on compressive strength, there are 12 grades of gypsum binders - from low-strength G-2 to high-strength G-25. According to the setting time, they are divided into fast-hardening (A), normal-hardening (B) and low-hardening (C).
According to the degree of grinding, gypsum binders are also divided into three groups: I, II, III.
Grades from G-2 to G-7 (groups A, B, C and I, II, III) are used for the manufacture of a variety of gypsum building products. Grades from G-2 to G-7 (groups A, B and II, III) are used for the manufacture of thin-walled building products and decorative parts. Grades from G-2 to G-25 (B, V and II, III) are used in plastering work, for sealing joints and for special purposes.
To increase strength and speed up setting time, gypsum binders are added to lime-sand mortars. They also give greater smoothness and whiteness to the plaster layer; they are used as the main substance in mastics.
Clay can be fatty, semi-fat (medium fat) and lean (loam). This division is determined by the degree of sand content in the clay.
Clay is used as a binding material in the manufacture of oven and plaster mortars, and is added to cement mortars intended for laying structures under conditions of normal air humidity.
Dense clay, free of impurities, is an excellent material for construction. Bricks are made from it.
If clay will be used in the construction of a house, its quality can be checked as follows. To do this, put 1 kg of material in a bucket and fill it with 4 liters of water, mix everything well and leave for 24 hours. Thanks to the water, the clay will become soft, and the sand will separate from the loam. Then the contents of the bucket are thoroughly mixed again and the water and the silty loam contained in it are drained so that only clay and sand appear at the bottom of the bucket. Weigh the clay and sand and subtract their mass from 1 kg - this way you can find out how much loam was in the material under study.
The quality of clay depends on its plasticity, and this can be checked by touch. Oily clay resembles a bar of moistened soap or a slice of lard. The quality of clay can be determined in another way. Having made a flagellum 15 cm long and 2 cm thick from clay, you need to pull it at both ends at the same time.
Skinny clay does not stretch well, and uneven edges form where the flagellum breaks. The flagellum, made of plastic clay, gradually stretches out, gradually becomes thinner and eventually ruptures, forming sharp teeth at the rupture site.
Its color depends on what impurities are included in the clay. Clay with an admixture of iron oxide and manganese oxide is colored red, yellow and brown, and clay with organic impurities is colored black.
Silty loam can be added to clay concrete to increase its strength and ability to maintain the desired shape after drying.
Construction solutions.
Mortars are mineral mixtures that harden and bond firmly to the stone.
The solution must contain a binder (cement, gypsum or lime), aggregate (gravel or sand) and clean water.
Depending on the purpose and use of mortar additives, the following solutions are prepared:
construction, for bricklaying;
plastering;
plaster;
cement.
The mortar for masonry should consist of sand and lime in a ratio of 3: 1 or 4:
1. You can add 1 or 2 shovels of binder to the mortar depending on its purpose.
Depending on the density (in a dry state), heavy (with a density of 1500 kg/m 3) and cement are distinguished. This is especially necessary when constructing walls that bear a special load. Sand and cement in this case are mixed in a ratio of 3: 1-6:
To prepare the plaster mortar, you can use both hydraulic lime and air lime.
It also contains sand. Distinguishes between plaster mortar for exterior use and plaster mortar for interior use. In the first case, hydraulic lime and sand are taken in a ratio of 1: 3; air lime - 1:2.
In the second case, hydraulic lime and sand are mixed in a ratio of 1:5, and air lime - 1:3.
Gypsum mortar differs from cement and lime mortar in its high strength and ease of preparation. To do this, take a container, pour water into it, pour out the plaster and mix everything thoroughly so that there are no lumps, which could later cause cracks to appear. Dilute the plaster with water immediately before working with it, because it may thicken ahead of time, then it will be impossible to work with it. To prevent this from happening, you can mix a little sifted sand into the plaster (2:
1), but because of this the strength of the gypsum will noticeably decrease.
Cement mortar is necessary for the preparation of durable plaster. To do this, take pure cement and water in a ratio of 1: 2 (1: 3).
Mortar additives are necessary to improve the quality of solutions. They significantly improve the physical and mechanical properties of solutions, their color, and frost resistance.
When coloring solutions, in addition to the usual additives, you can only use paints of bright colors that do not contain gypsum and barite impurities. Frost resistance is achieved by adding chlorides to the solution. They allow you to work with the solution at fairly low sub-zero temperatures.
Chlorides and other means of protection against exposure to low temperatures are used with the utmost caution, because an overdose of substances, as a rule, leads to the formation of smudges.
Construction mortars are characterized by three main parameters: density, type more) and light (density less than 1500 kg/m 3) mortars. To make heavy solutions, heavy quartz or other sands are used; fillers in light solutions are light porous sands made of pumice, tuff, slag, expanded clay, etc. Light solutions are also obtained using foaming additives (porous solutions).
Based on the type of binder, construction mortars are divided into cement (based on Portland cement or its varieties), lime (based on air or hydraulic lime), gypsum (based on gypsum binders) and mixed (based on cement-lime, cement-clay, lime-gypsum binders) . Solutions prepared with one binder are called simple, and solutions prepared with several binders are called mixed (complex).
According to their intended purpose, mortars can be masonry (for masonry, installation of walls from large-sized elements), finishing (for plastering rooms, applying decorative layers to wall blocks and panels), special ones with special properties (waterproofing, acoustic, X-ray protective).
The choice of binder depends on the purpose of the solution, the requirements for it, the temperature and humidity conditions of hardening and the operating conditions of the building. Portland cements, pozzolanic Portland cements, slag Portland cement, special low-grade cements, lime, and gypsum binders are used as binders. To save hydraulic binders and improve the technological properties of mortars, mixed binders are widely used. Lime in mortars is used in the form of lime paste or milk. Gypsum in plaster mortars is an additive to lime.
The water used for solutions should not contain impurities that have a harmful effect on the hardening of the binder. Tap water is suitable for these purposes.
If the solution is used in winter conditions, hardening accelerators are added to its composition, as well as additives that reduce the freezing point of water (calcium chloride, sodium chloride, potash, sodium nitrate, etc.).
The composition of a mortar is indicated by the quantity (by mass or volume) of materials per 1 m 3 of mortar or by the relative ratio (by mass or volume) of the original dry materials. In this case, the binder consumption is taken as 1.
For simple mortars consisting of a binder (cement or lime) and not containing mineral additives, the composition is 1: 4, that is, for 1 mass part of cement there are 4 mass parts of sand. Mixed mortars consisting of two binders or containing mineral additives are designated by three numbers, for example 1: 3: 4 (cement: lime: sand).
The quality of mortar mixtures is characterized by their workability - the ability to be laid without special compaction on the base in a thin layer, filling all its unevenness. Workability is determined by the mobility and water-holding capacity of mortar mixtures.
Mobility is the ability of a mortar mixture to spread under the influence of its own mass. Mobility is determined (in cm) by the depth of immersion in the mortar mixture of a standard cone weighing 300 g with an apex angle of 30° and a height of 15 cm.
The deeper the cone is immersed in the mortar mixture, the greater mobility it has.
The degree of mobility of the mixture depends on the amount of water, the composition and properties of the starting materials. To increase the mobility of mortar mixtures, plasticizing additives and surfactants are introduced into them.
The mobility of mortars, depending on their purpose and method of installation, should be as follows.
Filling horizontal joints when installing walls made of concrete blocks and panels; Joining vertical and horizontal seams - 5-7.
Water retention capacity is the ability of a solution to retain water when laid on a porous base. If the mortar has good water-holding capacity, partial suction of water compacts it into the masonry, which increases the strength of the mortar. Water-holding capacity depends on the ratio of the components of the mortar mixture. It increases with increasing cement consumption, replacing part of the cement with lime, introducing highly dispersed additives (ash, clay, etc.), as well as some surfactants.
The strength of the hardened mortar depends on the activity of the binder, the water-cement ratio, the duration and conditions of hardening (ambient temperature and humidity).
When laying mortar mixtures on a porous base that can intensively suck out water, the hardening strength of the solutions is much higher than the same solutions laid on a dense base.
The strength of a mortar depends on its brand, which is determined by its compressive strength after 28 days. hardening at air temperature 5-25 °C. The following brands of solutions are available: 4, 10, 15, 50, 75, 100, 150, 200 and 300.
The frost resistance of solutions is determined by the number of cycles of alternating freezing and thawing until the loss of 15% of the original strength (or 5% of the mass). Based on frost resistance, solutions are divided into Mrz grades from 10 to 300.
3.2 Selecting the brand and composition of the solution
The choice of solution depends on the type of building, its operating conditions, as well as the planned degree of durability.
Structures located above the ground with a relative air humidity inside of up to 60%, as well as underground structures in soils with a low level of humidity, are laid on cement-lime and cement-clay mortars. In this case, the solutions must have a ratio of the volume of lime (clay) paste to the volume of cement not exceeding 1.5:
If the humidity inside the building is more than 60% or the soil has high humidity, this ratio should not exceed 1:
1. Lime and clay are not used in mortars for masonry located below the groundwater level.
Cement-lime and cement-clay mortars in summer conditions are used in the construction of buildings whose height does not exceed three floors.
The grade of clay mortar used in dry climates is 10, in moderately humid climates - 2, and for mortars with additives - 4.
The consumption of binders depends on the composition of the solution, as well as the brand of binder and solution.
For laying walls made of dry and porous stone materials, mortars with greater mobility are used, for laying walls made of wet and dense materials - with less mobility.
In addition to solutions prepared from the materials described above. In modern finishing works, ready-made dry mixtures are used, which in their properties are not inferior to the above solutions. They are diluted immediately before use with water.
It should be noted that when high-quality plastering of the surface, beacon profiles are used, which are not removed after the leveling operation. And they seal it with mortar. Therefore, they should also be classified as materials.
4. Execution technology
The technological process of high-quality plastering of brick surfaces consists of the following operations: surface preparation, hanging, installation of beacons, wetting, spraying. applying one or more layers of primer, leveling the soil, applying a covering layer, grouting, finishing corners.
Surface preparation.
New stone and brick surfaces made in hollow areas (the seams between the bricks are not filled with mortar) have sufficient roughness, so there is no need to carry out additional notches on them. It is enough just to wipe off the construction dust from the surface, rinse the surface well with water, and, if necessary, remove dirt (oil stains, paint, glue). If the seams between the bricks are completely filled with mortar, then at the preparatory stage they must be deepened by 0.1-1 cm, cleaned with a steel brush, swept away the dust and washed.
Rough new concrete surfaces are cleaned of dust and moistened with water, smooth concrete surfaces are notched, and contaminated areas are cleaned with steel brushes or cut off.
Any stone and concrete surfaces that have stood unplastered for more than 1 year require mandatory notching, cleaning from soot and dust, and washing. All weak, easily chipped or peeling areas of the surface are beaten to a solid base.
Cleaning is usually done with a steel brush. If you attach it to a long handle, it will be more convenient to work, since you can hold it with both hands. The brush must be pressed firmly against the surface and moved in different directions to remove the thin top contaminated film. Heavily contaminated areas with oils, paints, and clay are cut down to such a depth that not the slightest trace of contamination remains on the surface.
Hanging.
There are two main ways of hanging surfaces and installing beacons using instrumentation (level, hydraulic level, laser level. The first method:
Surfaces to be plastered are checked by hanging in the vertical and horizontal planes with the installation of inventory removable marks according to Figure 2. It is most convenient to hang the walls with a plumb line, the hanging diagram of which is shown in Figure 2. In the corner of the wall, at a distance of 300 - 400 mm from the ceiling, nail 1 is driven in to the thickness of the plaster. A plumb line is lowered from the head of this nail to the floor and nail 2 is driven in at the bottom so that its head almost touches the cord, after which an intermediate nail 3 is driven in. The opposite corner of the wall is hung in the same way, nails 4, 5 and 6 are driven in alternately. Then the flatness of the wall plane is checked. . To do this, pull the cord from the 1st to the 6th nail and from the 2nd to the 4th nail. The cord should not touch the wall, otherwise the convex wall will be cut down. If it is impossible to cut down the convexity, remove nails 1, 2, 3 or 4, 5, 6 from one of the vertical rows and install them so that the normal thickness of the plaster remains in the convex places. Then intermediate nails 7 and 8 of the upper horizontal row are driven along the cord between nails 1 and 4, then nails 9, 10 and 11,12 are driven between nails 3 and 6 and 2 and 5.
According to the second method, which is more modern, after the specified marking with a laser level, beacon profiles are installed. Which are attached to alabaster.
The design of the lighthouse for construction work is a lightweight X-shaped profile 2.5 m long with a base width of 20 mm, a guide post height of 6, 10 or 15 mm. When carrying out construction work, first carry out a preliminary check of the wall, pulling the cord at the top, bottom and diagonally. This gives the first idea of where and what deviations from the vertical and plane there are, and allows you to determine the greatest convexity of the wall. Then, while carrying out construction work, in one of the upper corners of the wall, retreating 30 cm from its top, they place the first mark of the plaster mixture. When determining the height of the first mark (the mortar molding is equal to the height of the mantle), they are guided by the greatest convexity of the wall. Every 30 cm vertically along the marking axis, a mortar mixture for construction work is applied with slaps, into which the inventory beacon is pressed with a 2.5-3-meter aluminum level. Then, in increments depending on the length of the rule (for a 2-meter rule it is 1.7-1.8 m, for a 1.5-meter rule it is 1.2-1.3 m), subsequent beacons are set. They are aligned vertically to form a single plane. The installation of beacons is checked using a plumb line for construction work, a building level or a laser level with a vertical pipe. Recently, self-tapping screws are often used as brands, and their installation is carried out using the following technology. On the primed surface, vertical lines are marked at intervals equal to the working length of the rule; the outer lines are drawn 20-30 cm from the corners of the walls. In construction work, this process is called "beating" a line. It is performed by two workers; the dyed lace is pressed at the extreme points, pulled and released, leaving a mark on the surface. In the corners of the wall, as close as possible to the ceiling and floor level, holes are drilled on the marking lines with a short 6 mm drill. Dowels are hammered into them and self-tapping screws are screwed in, onto which a strong thread is pulled. Using a plumb line for construction work, pressing it against the wall as much as possible, check the verticality of the outer threads by tightening or unscrewing the screws. Additional screws are also installed under the verified vertical thread with a pitch of no more than 50 cm. When performing construction work, a horizontal thread is tied between the outer threads with a non-tightening loop. A kind of drawing rod is created, capable of moving up and down, and with its help self-tapping marks are placed on the internal marking lines. When all the self-tapping screws are exposed during the construction process, a layer of gypsum mortar or any quick-drying putty used in construction work is laid between them to a thickness exceeding the plane of the screw by 1 cm, and the inventory beacon profiles are immediately installed, first pressing them with your hands near the screws , and only then press them with a 2.5-3-meter rail against their heads until it stops. After the solution has set, the excess is cut off with a spatula, and after final drying, the beacons must be additionally secured securely with a plaster mixture. If, during construction work, the surfaces of walls or partitions are made with significant vertical deviations or clearly have a convexity, it is more rational to place inventory beacons for construction work in previously made furrows. This method is especially often applicable when builders, in order to correct defects on the concrete surface, have already completed the first leveling layer of gypsum plaster. First, near the location of the future construction beacon, holes are drilled in the wall, into which dowels are also hammered and self-tapping screws are screwed in plumb, so that the subsequent thickness of the plaster marking is minimal. When carrying out construction work to achieve this goal, after installing all the marks on the wall using self-tapping screws in the above manner, a vertical furrow is made 4-5 cm from them using a hammer drill. The beacon inventory profile is recessed into the recesses of this groove in the same plane as the marks and fixed with a solution. Using this method, all subsequent beacons for construction work are also installed in the plane of the wall with a step depending on the working length of the rule. Inventory mesh corners are used to protect the external corners of walls, window and door openings from mechanical damage. The mortar mixture is also applied to their inner surface in increments of 30 cm and the profiles are pressed to the corners of the slopes from the middle to the edges. The corners are installed in the same plane with the beacons. After the mortar mixture, which holds the beacons and protective corners, has set, the surface is prepared for plastering.
Preparation of applying the mortar mixture.
Pour 18 liters of clean cold water into a plastic container, based on one bag (30) kg of dry mixture. First, pour 7-10 trowels of dry plaster mixture and mix for 2-3 minutes. Then gradually pour out the rest of the construction mixture while mixing by hand with a trowel. After standing for 5-7 minutes, using a mixer for construction work or a drill with an attachment, the mortar mixture is mixed until a homogeneous consistency. In the process of preparing the mortar mixture, to achieve the required mobility, you can add dry mixture or water as needed, which cannot be done during its use. The mobility of the mixture should be 8-12 cm of immersion of a standard cone. The prepared plaster solution is applied to the surface within 20 minutes after mixing it with a wide plastic trowel or large metal spatula; on the wall - from bottom to top, on the ceiling - on yourself. It should be remembered that the prepared construction mortar mixture must be applied to the surface within 20 minutes after preparation.
Applying plaster layers.
Each layer of plaster consists of three separately applied layers - spray, primer and topcoat, which have a strictly defined purpose.
Spray is the first layer of plaster coating. The thickness of this layer when applied manually is from 3 to 5 mm. When applied with mortar pumps, the thickness of the applied layer should be no more than 9 mm on wooden surfaces, and no more than 5 mm on stone, concrete and brick surfaces. For spraying, prepare a liquid solution with a water content of up to 60% of the volume of binder. When determining the density of a solution applied mechanically, the sediment of the cone should be 9 cm, and that applied manually - 12 cm. Before applying the spray, stone and concrete surfaces must be moistened with water.
The purpose of the spray is that, flowing into all the pores and roughness of the surface, it firmly adheres to it and holds the weight of the soil and covering. The more correctly the spray solution is prepared, the better it will flow into all the roughness, the stronger it will adhere to them and the more firmly the plaster will adhere.
Primer is the second layer of plaster coating. The solution for the primer is prepared thicker than for spraying. Such a solution should be dough-like and contain water up to 35% of the volume of binder. The density of the soil solution, regardless of the method of applying it to the surface to be plastered, should be equal to 7-8 cm of cone settlement.
The soil is the main layer of the tent. It forms the required thickness of the plaster and evens out surface unevenness.
If the thickness of the plaster crust is large, then the primer is applied in several layers. The thickness of each of these layers should not exceed 10 mm.
The covering is the third layer of plaster crust. It should be 4 mm thick. Along the cone, the thickness of the solution for covering without adding gypsum should be 7-8 cm, and for covering with the addition of gypsum 9-12 cm.
The covering evens out the surface of the soil, forming a smooth, thin film that can be easily wiped off.
The coating solution must be prepared from fine sand, sifting it through a fine sieve with 1.5X1.5 mm holes.
To form a plaster mark, the solution is applied to the surface manually and by machine. The thickness of the covering for any method of applying the solution, after leveling and grouting, should be no more than 2 mm.
Application of plastic mortars for large volumes of work should be carried out only by machines. In exceptional cases, and only for small volumes of work (for example, repairs), due to the inexpediency of using machines, the solution can be applied manually.
By manually applying the solution we mean two completely different operations: throwing and spreading.
When pouring the solution, it hits the surface with force and is compacted, resulting in the creation of a plaster crust of equal strength and porosity without voids and cavities.
To increase labor productivity, the solution is spread, spreading it over the surface in a thin layer. Spreading the solution is done with a falcon, grater or spatula.
When spreading a thick mortar, if there is not enough pressure on the tool, the plaster crust turns out to be less dense than when thrown on, and with a large number of internal cavities. However, you should not press too hard, as the person working will quickly get tired.
The technique for throwing mortar from a falcon with a plastering spatula consists of scooping the mortar onto the falcon, taking a portion of the mortar from the falcon and applying it to the surface to be plastered. It should be remembered that the correct grip of the tool increases the productivity of the plasterer and makes the work easier.
While working, the plasterer takes the falcon with his left hand and the spatula with his right, approaches the box with the mortar and stands so that his right leg is closer to the box and his left leg is set back. The falcon is placed on the side of the box with one side, and the other is raised 10 cm. This position of the falcon is very convenient for collecting the solution. The first portions of the solution are placed on the upper side of the falcon, and then in successive rows on the lower side (Fig. 3).
Having collected the required amount of solution onto the falcon, the falcon must be straightened, i.e. remove excess from edges. While scooping up the mortar, the plasterer should hold the falcon on his hand. This makes the work easier and gives the falcon stability.
When plastering a wall, the falcon should be slightly inclined towards it so that the plasterer does not get his hands dirty with the solution. It is advisable to take a portion of the solution from the falcon with the right edge or the end of the spatula so that it moves from the edge of the falcon (away from you) to its middle (Fig. 50).
When throwing the solution onto the surface with a spatula, they do not work with the whole hand, but only with the brush. In this case, the worker swings the blade with a sharp stop, which ensures that the solution quickly flies off the blade. The swing should not be very strong, since a sharp push will cause the solution to splash. Figure 4 shows the various positions of the plasterer's body when throwing the mortar onto the surface to be plastered with a spatula.
To increase labor productivity, many plasterers apply mortar onto the walls with a spatula directly from the box. At the same time, they use a lightweight mobile box and an oversized paddle. The technique for throwing the solution remains the same as when throwing it with a spatula from a falcon.
The work is organized as follows. If the surface to be plastered is located below the level of the box, then it is installed at a distance of 1 m from the wall. The plasterer takes a portion of the mortar from it with a spatula and throws it onto the walls (Fig. 5). If the solution is thrown above the level of the box, then it is placed next to the wall. This reduces unnecessary movements, and the solution flying off the wall falls directly into the box. During work, I periodically move the box to the place where the solution is poured.
When plastering the upper parts of walls and ceilings, it is advisable to use a trolley designed by plasterer Y.S. Karasev (Fig. 5). The cart is made of metal, on four wheels. It rises and falls by pressing the lever.
Rice. 5. Fig. 6
A small box made of metal or thin plank is placed on the cart. Typically you should have two or three drawers to work with. Then the box, freed from the solution, is quickly removed from the cart, and a box filled with solution is placed in its place.
When working with a cart, the plasterer stands next to it, takes a portion of the mortar from the box with a plaster spatula and throws it on the wall or ceiling. For ease of operation, the box with the solution is raised or lowered, depending on Fig. 6.
from the height of the plastered area. When plastering ceilings, the box should always be under the area being plastered.
Application of the trolley designed by Ya.S. Karaseva makes it possible not to make unnecessary movements, which helps to increase labor productivity.
Throwing the solution directly with a falcon.
Many plasterers apply the mortar directly with a falcon. The mortar is scooped onto the falcon using a plaster spatula, scoop or ladle. Using a bucket or scoop is more productive than using a shovel.
To apply the solution directly with a falcon, onto which about 2 liters of thick solution is collected, you should master the necessary skills. You can throw the solution with a falcon on walls, ceilings, and also cornices. When working, use a mobile box, which is installed at a distance of 1.2-1.5 m from the wall to be plastered.
The falcon with a portion of the mortar placed on it is taken with the right hand and with a strong sharp swing from the bottom up, the entire mortar is thrown onto the surface to be plastered, which is spread over the surface in a wide strip. The position of the worker’s body when performing the throw remains the same as when applying the solution, using a spatula from a falcon (Fig. 6). To facilitate the work, it is advisable to use light metal falcons, which are convenient for throwing the solution. When the mortar is thrown onto the ceilings, the box should be under the throwing area. In all cases, it should be moved to the place where the work is being done.
Labor productivity when throwing mortar with a falcon increases by 25-50% compared to working with a spatula.
Throwing mortar with a ladle.
Throwing mortar with a ladle is widely used, since it is much more productive to work with it than with a spatula. When throwing the solution with a ladle, many operations are reduced: repeatedly scooping the solution onto the falcon with a spatula, throwing it off the falcon, etc.
Various buckets are used for work. The most common is the A.S. bucket design. Shaulsky, as the most convenient to use (Fig. 7). The ladle consists of a cup and a handle. The cup is stamped from thin, durable steel. A handle is attached to the cup with rivets, onto which a wooden handle is mounted. Bucket capacity 0.75 l.
When working with a bucket designed by A.S. Shaulsky's correct grip, shown in Fig. 7, is important, which improves and facilitates the throw and reduces solution loss.
You can use buckets to throw the solution onto all types of surfaces and rods.
It is not recommended to throw quick-setting lime-gypsum mortars with a ladle, as they “grow” on it, making the ladle heavier.
Preliminary training in working with a ladle should be carried out on clay solutions of medium thickness. After mastering the work technique, you can move on to applying lime, mixed and cement mortars.
When plastering walls, a mobile box is installed at a distance of 1 m from the wall, the ladle is taken in the right hand, a portion of the solution is taken with it, and the solution is thrown onto the surface with a strong wave of the hand. The movement of the hand with the ladle must be given such force that the solution flies out of the ladle without stopping in it, and spreads out over the surface like a fan. This throw is considered the most correct. In order for the solution to lay on the surface to be plastered in an even thin layer, it is necessary to place the ladle in such a position that its edge seems to disperse the solution, directing it in a thin stream.
Spreading the solution from the falcon.
One of the most common methods of applying the solution is to spread it from a falcon onto walls and ceilings. Apply only the primer and cover solution, but not the spray.
Spreading is done like this. Take a spatula in your right hand, and a falcon with a solution in your left. Then the falcon is placed on the surface to be plastered so that one side of it is 5-10 cm from the surface (this depends on the amount and thickness of the solution), and the other is pressed against it so that there is a gap between the surface to be plastered and this side of the falcon canvas by thickness of the applied layer of solution. To create the necessary pressure on the solution, the falcon is pressed to the surface with the end of the spatula, placing it against the key. As the falcon moves, the solution is spread onto the surface, and the raised side of the falcon is gradually pressed against the surface. The pressure of the spatula on the falcon must be done evenly in order to obtain a flat surface that does not require additional leveling and smoothing. (Figure 8).
When spreading the solution on the walls, the falcon is guided from the bottom up, forming vertical or curvilinear stripes).
Spreading the solution with trowels.
To spread the solution, narrow and wide, long and short graters are used, which are made from pine boards that do not have knots or tar. The grater blades have a width from 5 to 20 cm, which depends on the length and purpose of the grater. The handles of the graters are firmly attached to the canvas with wooden dowels, nails or screws. Large graters are used for spreading and leveling the mortar and for rubbing corners and chamfers. The edges of the graters are sometimes bound with steel, which protects the blade from warping and makes it easier to cut off the hardened mortar. For spreading, it is recommended to use wide graters (15-20 cm wide), since a wide grater holds more solution, which helps to increase labor productivity.
When working, one end of the grater is placed on a box, a bed of mortar is placed on it with a spatula, and then taken with both hands and brought to the surface, pressing one longitudinal side of the grater against the wall and lifting the other. If they are plastering a wall, move the trowel from the bottom up, and if they are plastering the ceiling, push it towards itself, thus applying strips of mortar of the same thickness to the surface.
Leveling the solution.
When first leveled, the surface usually has many defects, voids, etc. Therefore, such places should be filled with solution and the process repeated until a smooth, rough surface is obtained. Primer can also be applied to the surface of the wall between the beacons in another way - by spreading the solution with a falcon. In this case, the lower part of the falcon with the solution is brought closer to the wall at a distance equal to the thickness of the plaster layer, and the upper part is set back from the wall by 100 mm. The falcon is moved from bottom to top. As it moves, the solution is spread onto the surface. (Fig.9).
The applied mortar mixture is leveled along the beacons using zigzag movements. The mixture remaining on the working surface of the rule is removed with a trowel for construction work and applied to unfilled areas, and then leveled again with a rule or a wide spatula. After the mortar begins to set (approximately after 45-70 minutes), protruding irregularities in the mortar mixture are cut off with a trapezoidal rule or a wide spatula.
Rice. 9 Fig. 10.
When carrying out the leveling operation, the evenness of the surface is checked using the rule (Fig. 10)
Covering, grouting and smoothing plaster.
The final process of finishing plaster is coating and grouting. Instead of grouting the plaster, it is often smoothed.
The cleanliness of the plaster surface depends on the correctly prepared coating solution. A well-prepared solution grouts faster, which increases the productivity of plasterers. Preparation of mortar and application of plaster coating Solutions for coating are prepared either manually or with a mortar mixer. Moreover, all materials must be strictly dosed, and the solution must be mixed until it is completely homogeneous.
The sand for preparing the covering should be fine-grained, since coarse-grained sand makes the surface rough.
The covering is carried out with the same solution from which the plaster primer is made. On cement soil they cover with cement mortar, on complex soil - with complex mortar, on limestone and lime-gypsum - with lime mortar. It is not recommended to add gypsum to the coating solution because when grouting it quickly softens and the strength of the coating layer decreases. If you still have to add gypsum, then you need to add it in very small quantities.
For convenience and speed of work on covering surfaces, the solution should be prepared:
for covering with solutions containing gypsum, with a cone draft of 9-12 cm, and for covering with solutions without gypsum - 7-8 cm.
The selection of the solution composition is of great importance both for obtaining the required surface cleanliness and for facilitating leveling and grouting. Solutions with normal fat content are easily rubbed and allow you to obtain a clean surface. Fatty solutions give a rougher surface with more grinding and unrubbed stripes. Skinny solutions are not strong enough and have the same disadvantages as fatty ones.
Before applying the covering layer, the soil is moistened with water using a brush. The solution is thrown onto the surface with a trowel, leveling it with a trowel using wave-like movements from bottom to top. After the covering layer has dried a little, and the plaster layer is no longer floating, but is still wet, grouting should begin. Grouting is done with a trowel. To do this, take it in your right hand, pressing it tightly against the plaster, and move it around the surface counterclockwise. In this case, individual tubercles are cut off with a grater, and the cut solution falls into the recesses, which helps level the surface. If, after grouting, there are still shells left, add a certain amount of solution and grout them. When the covering layer dries, before grouting begins, it is moistened with water using a brush. (Fig. 11).
When carrying out plastering work, special attention should be paid to finishing the edges and corners. The edges must be exactly vertical or horizontal. To make the angle of the edge sharp, a flat board is applied and attached to the edge of the wall so that it protrudes from the plane of the wall by the thickness of the plaster layer. After the plaster has hardened, the board is removed. Corners that may be subject to destruction during operation should be reinforced with a metal mesh or strip and sealed well with mortar.
You can also derive husks and stubs using husk and stub rules. (Fig. 12). Carefully rub the surface with them. Corners can also be leveled using corner trowels (Fig. 13).
Fig.12 Fig.13
5. Quality requirements
List of operations subject to control when installing plaster coatings.
| Name of operations subject to control | Quality control of operations | ||||
| The work contractor | master | compound | ways | time | involved services |
| Acceptance of surfaces for plastering work | - | Evenness, verticality and horizontality of surfaces | Visually, using a rod, plumb line and other measuring instruments | Before starting plastering work | - |
| Acceptance and quality control of plaster mortar | Cone settlement, plasticity, presence of foreign inclusions | Visually, laboratory | Before and during the work process | Laboratory | |
| Preparing surfaces for plastering | Cleaning surfaces from dust, dirt, grease stains, hanging surfaces and installing beacons | Visually, using a staff and a plumb line | |||
| Applying plaster layers of spray, primer, covering. Finishing rustications, window and door slopes | Dosing of additives. Thickness and deviations using measuring tools | During the plastering process | Laboratory | ||
| Applying plaster layers of spray and covering. Finishing rustications, window and door slopes | Dosing of additives (cement, gypsum) for the plaster layer depending on the surface to be plastered, the thickness of the layers and compliance with permissible deviations | Dosing of additives. Thickness and deviations using soil measuring tools | During the plastering process | Laboratory |
| Acceptance of completed work | Appearance, verticality, horizontality and surface irregularities | Visually, rod, plumb line, meter and other measuring instruments | After finishing plastering work |
Plaster defects and measures to prevent them.
Defects in plaster can be in the form of dents, cracks, peeling, etc. and occur for various reasons. To obtain high-quality plaster, it is necessary to take measures to eliminate these defects.
Ducts - the appearance of swollen places on the surface of the plaster. In the center of each swollen area there is a white or yellow dot or yellow spot.
Blisters are formed because the solution was prepared with unseasoned lime, in which individual small particles were not quenched. Once in the plaster, they begin to extinguish after a while. At the same time, the suppression continues for years. To avoid swelling, freshly slaked or slightly aged lime dough used to prepare the solution must be strained through a sieve with a cell cross-section of no more than 1.5X1.5 mm.
Yellow spots in swollen places are formed because small dry lumps of clay got into the solution along with sand. The sand used to prepare the solution must be washed well or sifted through a fine sieve.
Shrinkage cracks are many large and small cracks that appear on the surface of the plaster. Cracks are formed because either greasy or poorly mixed solutions are used, in which a lot of binders or a lot of fillers accumulate in places.
Shrinkage cracks are formed from the use of thawed lime-gypsum mortars or from the rapid drying of the applied plaster under the influence of strong draft winds and high temperatures. Cracks also appear when thick layers of mortar are applied at once or because the mortar is applied in thin layers to freshly applied unset mortar. To avoid this, it is necessary to prepare solutions of normal fat content, strictly dosing binders and fillers and mixing them well during the preparation of the solution.
Rejuvenated solutions (rejuvenation) should be added to a freshly prepared solution in an amount not exceeding 10%.
The applied plaster must be protected from excessively rapid drying and from strong winds, for which it is necessary to close windows and doors in plastered rooms. On facades, plaster should be covered with wet matting or watered frequently.
The solution should be applied in thin (no thicker than 10 mm) layers and only on well-set previous layers.
Peeling and swelling of the plaster occurs because plastering was carried out on damp surfaces or because after plastering they were subjected to constant moisture. Most often this happens on lime and lime-gypsum plasters.
In order to avoid peeling and swelling of the plaster, it is necessary to dry the damp areas thoroughly and only then begin plastering.
Cracks in the form of cages form on both wooden and brick surfaces: on wooden shingles in cages, and on brick surfaces along the seams of masonry. On wooden surfaces, this happens because a too thin layer of mortar is applied to them or a very wide shingle is filled in, which warps under the layer of plaster and tears it, forming cracks. Cracks form on brick walls because very thin layers of plaster are applied to them.
To prevent cracks from forming, it is necessary to use shingles no wider than 2 cm, and the thickness of the plaster layer should be: on brick surfaces - at least 1.5 cm, and on wooden surfaces - 2 cm above the level of the exit shingles.
Peeling of plaster occurs for various reasons, regardless of the solution. The reason for peeling may be that layers of mortar were applied to a dry surface not wetted with water, to dry layers of a previously applied mortar, or that subsequent layers of mortar were applied to stronger previous ones. For example, peeling can occur if very strong gypsum mortar is applied to the lime-gypsum mortar.
Peeling can also occur if the concrete base is plastered with lime or lime-gypsum mortar without passing layers. To avoid this, concrete surfaces should first be sprayed with cement, then complex and then lime mortar.
Peeling of colored and decorative coating layers occurs because they are applied to very strong soils or to soils with an insufficiently rough surface or to weak soils when the coating layer is stronger and denser than the soil itself.
Cracks in husks and plaster occur because the mesh strips were not filled in the corners of the walls or at the joints of dissimilar surfaces, or because the solution is applied to overdried wooden surfaces, to unsteady or poorly secured structures.
Before plastering, corners and joints of dissimilar surfaces should be tightened with strips of mesh and nailed down. Dry wooden walls, partitions, and ceilings should be thoroughly moistened with water before plastering.
Science and practice have long established the nature of defects in plaster coatings and the reasons that give rise to them. The most offensive thing is that all defects should not occur at all if work is done conscientiously, subject to well-known technological rules.
There are four main reasons leading to marriage:
poor quality of materials for the solution;
non-compliance with the rules for preparing main surfaces for plastering;
improper performance of work;
careless use of individual surfaces.
Let's look at each of these reasons.
So, about solutions. First of all, you need to remember that the incorrect choice of solutions can lead to the formation of defects. Namely: the use of too thin solutions leads to a decrease in the strength of the plaster, too fatty solutions cause shrinkage cracks (only pure gypsum solution does not cause cracks).
The cause of cracks in plaster is the use of mortar that has already begun to set in the box.
Before use, boiling lime is quenched with water and turns into either lime paste or fluffed lime.
Lump lime always contains particles that take the longest to quench. And if you do not keep the slaked lime for a certain time, but immediately put it into the solution, then the unslaked particles will get into the plaster layer. They will definitely then interact with moisture, and such a process can reveal itself even after 2...3 months. Most often and most likely they appear in external plaster, which is constantly in a humid environment.
The lime particles, which continue to be slaked in the plaster layer, increase in volume, swell the plaster - and the outer crust bounces off, leaving shells on the plane. Builders call this phenomenon “dutik” or “plaster pox”.
How to deal with "dutiks"? Slaking lime correctly. Before releasing lime milk, it must be passed through a 0.6 mm sieve.
Poor-quality fluff obtained from the factory can also lead to defects - it may also contain unextinguished particles. Sometimes fluff is brought in burst bags, this indicates that it has increased in volume - it was extinguished until it reached the construction site. The fluff is unusable and warm to the touch. To avoid troubles, it should be soaked in water for a day. With plaster it's easier. If it does not grip well, it will become clear immediately and, naturally, it will not be allowed into use. Poorly stored cement is unsuitable for mortar. This will be indicated by the presence of lumps and blocks in it. The formation of “dummies” can be caused by the use of unwashed sand contaminated with clay. Particles of this clay, when wet, increase in volume and behave in the plaster layer, like unslaked lime. To eliminate “dubs,” the damaged areas are cleared and sealed with mortar flush with the surface of the plaster.
HYPERLINK "http://www.liveinternet.ru/click" \t "_blank" The cause of cracks in the plaster is the use of mortar that has already begun to set in the box.
| Deviations | Type of plaster | |||||
| simple | improved | high quality | ||||
| Surface irregularities (detected when applying a rule or template 2 m long) | No more than three irregularities with a depth or height of up to 5 mm | No more than two irregularities up to 3 mm | Depth or height |
|||
Surface deviation: from vertical from horizontal |
15 mm for the height of the room 15 mm for the entire room | 2 mm per 1 m of height, but not more than 10 mm for the entire height of the room 2 mm per 1 m of length, but not more than 10 mm for the entire length of the room or its part limited by purlins, beams, etc. | 1 mm per 1 m of height, but not more than 5 mm for the entire height of the room 1 mm per 1 m of length, but not more than 7 mm for the entire length of the room or its part limited by purlins, beams, etc. | |||
| Deviations of husks, usenki, window and door slopes, pilasters, pillars, etc. from vertical and horizontal | 10 mm for the entire element | 2 mm per 1 m of height or length, but not more than 5 mm for the entire element | 1 mm per 1 m of height or length, but not more than 3 mm for the entire element | |||
| Deviations | Type of plaster | |||||
| simple | improved | high quality | ||||
| Deviations of the radius of curved surfaces from the design value (checked with a pattern) | 10 mm | 7 mm | 5 mm | |||
| Deviations of the width of the plastered slope from the design | Not checked | 3 mm | 2 mm | |||
| Deviations of rods from a straight line within the limits between the angles of intersection of rods and braces | 6 mm | 3 mm | 2 mm | |||
6. Organization of labor and workplace
When performing plastering work, it is necessary to use a flow method, dividing the process into separate technological operations, the nature and quantity of which depend on the type of plaster and the material of the surfaces being plastered. However, with insignificant volumes, their entire complex (surface preparation, application and leveling of solutions, grouting, pulling rods, finishing slopes, etc.) is performed by one link. The performance of plastering work is associated with the leading technological process - the construction of the above-ground part of the building. To increase labor productivity and skills, workers carry out internal plastering work using the flow-dissected method. One of the progressive forms of labor organization during plastering work is the work of crews at plastering stations. The crews are equipped with a full set of mechanization tools, devices and equipment, including a plastering unit for receiving imported mortar, nozzles, trowels, etc. The main form of organization of crew labor is team work. Typically, brigades and crews consist of 18-23 people (4-5 units).
Scheme of organization of the workplace of unit No. 1.
Two plasterers (Sh 3 - 3 ranks, Sh 2 - 4 ranks) visually and using a lath determine the deviations of the base from the vertical, then they clean the surface. Along the walls, a plasterer (W 5) of the 2nd category installs collectors. After this, the plasterer (Ш 3) gives a signal to the station driver to turn on the mortar pump. By moving the nozzle from left to right and from top to bottom at an angle of 60° - 90° to the surface, the plasterer (W 1) applies a layer of spray. The plasterer (Ш 4) supports the hose, providing the first plasterer with free movement along the front of the work, and the plasterer (Ш 5) monitors the condition of the pressure hoses, preventing them from twisting and bending.
At the same time, as the spray is applied to the surface of the plaster (Ш 2; Ш 3), the resulting sagging is leveled using the rules. Excess solution is dumped into collectors. When leveling the soil layer, one of the plasterers (W 3) moves the float from bottom to top in a zigzag motion to the right and left, pressing it against the wall parallel to the floor so that an acute angle is formed between the lower part of the float and the wall. Another plasterer (Ш 2) uses a control rule to check the surface of the primed wall in all directions. If necessary, grease the remaining large shells and gaps. The solution is applied with a plaster spatula and leveled with trowels.
In conclusion, the plasterers (Ш 1; Ш 4) use the rules from top to bottom and bottom to top to cut the corners. The lines of husks and appendages after finishing should be straight and vertical.
The second link of the team applies a coating layer on the surface of the walls and grouts the coating layer using a mechanized method. First, the plasterer (Ш 6), having given a signal to turn on the covering unit, applies a covering layer on the surface of the walls using a universal fishing rod in a circular motion from left to right and from top to bottom.
The layout of the workplace of unit No. 2 is shown in Figure 11. Simultaneously, as the covering layer is applied, two plasterers (Ш 7; Ш 8) pull up and level the covering layer with a trowel, moving it in different directions. In this case, the upper edge of the grater is raised to avoid cutting off the solution. Excess solution is fed into collectors.
Figure 11 - Scheme of organization of the workplace of unit No. 2.
Sh 6, Sh 7, Sh 8 - locations of plasterers
1 - scaffolding table; 2 - tool box; 3 - collectors for solution; 4 - flexible hose of the mortar pump; 5 - trowels; 6 - electrical cable coming from the current converter.
The arrow indicates the direction of movement of the plasterer (W 6)
The plasterers of the link (Ш 6; Ш 7; Ш 8) perform the grouting of the covering layer by pressing the rotating disks of the trowels against the surface of the walls being processed and moving them.
Rub the covering layer until scratches, cavities and bumps disappear. The water supply is regulated by valves located on the bodies of the trowels. Places inaccessible to mechanized grouting are processed manually with trowels.
The organization diagram of the workplace of link No. 3 is given in Figure 12.
Plasterers (Ш 9; Ш 10; Ш 11; Ш 12; Ш 13; Ш 14), standing on a scaffolding table, use a brush to moisten the surface of the slopes with water for better adhesion of the mortar and apply a layer of spray and soil with a trowel at intervals of time, depending on the brand of solution used and temperature conditions.
The soil is leveled using wooden trowels and trowels along the guide rails.
Figure 12 - Scheme of organization of the workplace of unit No. 3
Ш 9 - Ш 14 - plasterers' workplaces;
1 - scaffolding table; 2 - box for solution; 3 - bucket; 4 - guide rail; 5 - tool box
The covering layer is applied with trowels, leveled with mallets and rubbed with graters, periodically wetting the surface with water. The verticality and horizontality of the plaster surface is checked using a plumb line, square and level.
Then the guide rails are removed, the angles of intersection of the slopes are leveled, and the husks and appendages are trimmed.
7. Safety precautions
When performing simple, improved and high-quality plastering of internal surfaces, the following dangerous and harmful production factors may arise due to the nature of the work:
increased dust and gas contamination of the air in the working area;
location of the workplace near a height difference of 1.3 m or more;
sharp edges, burrs and roughness on the surfaces of finishing materials and structures;
insufficient illumination of the work area.
To prevent workers from being exposed to hazardous and harmful production factors, the safety of plastering work must be ensured by observing the following measures:
organization of workplaces indicating methods and means for providing ventilation, fire extinguishing, protection from thermal burns, lighting, performing work at heights, using scaffolding and using other means of small-scale mechanization;
methods and means of supplying materials to workplaces must ensure labor safety.
Persons at least 18 years of age who have professional skills, have passed a medical examination and are found fit, and have acquired knowledge of safe labor methods and techniques in accordance with GOST 12.0.004-90 "SSBT. Organization of occupational safety training" are allowed to carry out internal plastering work using scaffolding means. General Provisions", having passed the examinations of the qualification commission in the prescribed manner and received the appropriate certificate.
Extraordinary safety briefings are carried out when finishing workers are transferred from one site to another, when work conditions change, or when the team violates labor safety rules and instructions.
Before starting work, the plasterers, the mortar pump operator and the maintenance team are given initial instructions at the workplace on how to safely carry out work, with the results of the instructions being recorded in the “Journal of registration of instructions at the workplace”.
Newly hired employees must undergo induction training with an entry in the “Logbook of registration of induction training on labor protection.”
Only workers who have undergone special training in accordance with GOST 12.0.004-90 "SSBT. Organization of occupational safety training. General provisions", workplace briefing on occupational safety and health and who have category III electrical safety are allowed to work with electrified tools.
When dry cleaning surfaces and other work involving the release of dust and gases, it is necessary to use respirators and safety glasses.
Workers engaged in plastering work or working in conditions of increased dust and gas contamination in the air of the work area must be provided with individual and collective protective equipment in accordance with GOST 12.4 011-89 "SSBT. Protective equipment for workers. General requirements and classification."
Before starting work, machines and mechanisms used to supply the solution are checked at idle speed. The housings of all mechanisms must be grounded, current-carrying wires are reliably insulated, and the starting switches are closed.
Persons who have undergone special training and passed occupational safety exams are allowed to operate machinery.
Disassembly, repair and cleaning of nozzles of machines used for plastering is permitted only after the pressure has been relieved and the machines have been disconnected from the network.
The plasterer-operator's workplace must be connected by an audio alarm to the plastering machine operator's workplace.
The materials and air hoses of the mortar pump must be periodically tested to twice the operating pressure.
When the mortar pump is operating, do not bend the supply hoses. Blowing out hoses with compressed air to remove blockages is permitted only after people have been removed from the premises. Upon completion of work, it is prohibited to remove the air valve and adapter pipe without making sure that the pressure has dropped to zero. When working with a mortar pump, you must:
ensure that the pressure in the mortar pump does not exceed the permissible standards specified in the passport;
remove mortar plugs and carry out repair work only after disconnecting the mortar pump from the network and relieving the pressure;
purge the mortar pump in the absence of people in the area of 10 m or closer;
When applying the solution, hold the nozzle at a slight angle to the surface to be plastered and at a short distance from it.
Portable tools, machines, lamps must have a voltage of no more than 42 V.
When using electric or liquid fuel-fired air heaters for drying plastered surfaces of premises of a building or structure, it is necessary to comply with the requirements of PPB 01-03 “Fire Safety Rules in the Russian Federation”. It is prohibited to dry rooms with open type heaters and other devices that emit fuel combustion products.
The work area during plastering work must be illuminated in accordance with SNiP 23-05-95 "Natural and artificial lighting" and GOST 12.1 046-85 "SSBT. Construction. Standards for lighting construction sites." Illumination of workplaces must be at least 30 lux. The temporary lighting project must be developed by a specialized organization commissioned by the contractor.
When using compositions containing harmful and flammable substances, there must be primary fire extinguishing equipment at the workplace, windows in the room must be slightly open to ensure ventilation, and workers must be provided with respirators and other personal protective equipment.
When preparing plaster solutions at the workplace, it is necessary to use for these purposes premises equipped with ventilation that does not allow an increase in the maximum permissible concentrations of harmful substances in the air of the working area. The premises must be provided with harmless detergents and warm water.
When performing plastering work on internal walls and partitions, it is necessary to strictly comply with the requirements of health and safety, environmental and fire safety in accordance with:
SNiP 12-03-2001 "Occupational safety in construction. Part 1. General requirements"
SNiP 12-04-2002 "Occupational safety in construction. Part 2. Construction production";
GOST 12.0.004-90 "SSBT. Organization of occupational safety training. General provisions";
GOST 12.1 004-91* "SSBT. Fire safety. General requirements";
POT RM-016-2001 Interindustry rules on labor protection (safety rules) during the operation of electrical installations;
PPB 01-03 Fire safety rules in the Russian Federation;
SP 12-135-2003 Occupational safety in construction. Industry standard instructions on labor protection.
List of used literature
1. Belogurov V.P. Handbook for a young finisher. - M.: Higher School, 1992, 237 pages.
2. Belousov E.D. Finishing technology: Textbook for vocational schools - M.: Higher school, 1995 ed. Revised 245 pp.
3. Belousov E.D. Vershinina O.S. Painting and plastering works. - M.: Higher school. 1990 347 pp.
4. Zubrilina S.N. Plasterer's Handbook. - Rostov-on-Don.: Phoenix, 2003.231 pp.
5. Mitkin B.A., Titov A.I. Reference manual on finishing works. - Mn.: Higher school 1997.11 ed. Revised. 157 pp.
6. New methods of producing finishing works / translated from German by G.G. Grechushnikova. - M.: Stroyizdat, 1990.234 pp.
7. Pivanov A.M. Plastering work: A practical guide. - M.: Stroyizdat, 1990.321 pp.
8. Chmyr V.D. Materials science for finishers - builders. Materials for painting and plastering works. - M.: Higher School, 1990.235 pp.
9. Shepelev A.M. Plastering works 11th edition. - M.: Higher School, 1988.341 pp.
10. Plastering, puttying and painting works: Practical guide / Rudenko V.I. - Stroyizdat, M.: 2008.249 pp.
Most often, documents, estimates or technical specifications related to repair work in a room, be it an apartment or a house, contain the following term - high-quality wall plaster. Such concepts, denoting a certain complex of technical operations, are often not deciphered. Therefore, there are cases when the essence of the assigned task is not clear, and often this point leads to misunderstanding between the employee and the customer.
It is important to know exactly and have an idea of what needs to be done, how, and what requirements exist according to GOST and SNiP regarding the performance of such work. Thanks to this, you can avoid all kinds of conflicts and carry out home repairs at the highest level. This is exactly what we will talk about in the article. You will learn GOST standards for high-quality wall plaster, how it is performed and what its features are. In addition, SNiP (building codes and regulations) will be considered regarding high-quality wall plaster, the required layer thickness and the quality of the mixture itself.
Classification of plaster finishing
Based on Russian SNiP 3.04.01-87, which is called “Finishing and insulating coatings”, there are 3 classes of surface finishing with plaster, which differ in quality:
- Simple wall decoration with plaster.
- Improved.
- High quality surface finish.
Important ! All relevant requirements and building standards for the quality of work, which are specified in the document, apply not only to manual plastering of walls, but also to mechanized plastering.
What is the difference between the finishing classes specified in SNiP? Each of them implies strict compliance with the rules and requirements of GOST.
A little about layers of plaster
Before describing the types of plaster based on quality, it is important to consider everything about the finishing layers. This information will be needed to understand the whole essence of the topic. What does the finish consist of?
- First of all, the base is sprayed or prepared for further layers. For this, a solution of liquid consistency is used. It provides reliable adhesion (adhesion) of the surface to the plaster. In addition, the mixture gives the surface the ability to repel moisture. Recommended layer thickness is 3-5 mm.
- The second stage, according to SNiP, begins with the application of primer. What is its purpose? It levels the main plane of the surface. When performing work, a solution of dough-like consistency is used. The thickness of this layer is 7-8 mm.
- The next layer is the covering. It is used to smooth out small defects and smooth out the coating. This uses a mixture that has the consistency of sour cream. The recommended thickness of such a layer is around 2-5 mm. Based on the requirements of GOST 8736-93, the fraction of sand particles should not exceed 1.2 mm.
Important ! Another important point specified in SNiP is that when the total thickness of the improved wall plaster exceeds 20 mm, then the base must be pre-reinforced. A polymer or metal reinforcing mesh is suitable for this work.
Now let's talk about how the 3 types of finishes differ, based on the layers of the finished mixture.
Differences in quality of plaster
If we talk about SNiP for plastering walls, it is important to understand what the difference is between the finishing classes. For example, simple finishing is most often used in basements, warehouses, attics and utility rooms. Simply put, in all non-residential premises where there is no need to create a perfectly flat surface. In this case, the finishing layers are as follows:
- spray;
- 2nd layer - primer.
This allows you to hide the main irregularities without additional labor and financial costs. The maximum thickness of simple plaster walls is 12 mm.
Improved wall plaster is used in residential premises that are used by humans. It is important to make the surface smooth and beautiful, since it is constantly in sight. It is applicable for private houses, high-rise apartments, educational institutions, medical and public buildings. In this case, the coating consists of:
- spray;
- 2 layers - primer;
- 3 layers.
This way, you can remove the smallest defects and irregularities, making the surface smooth and beautiful. The average total thickness of improved wall plaster is 15 mm.
High-quality surface plaster is the most technologically advanced. It is used for residential buildings, public, educational and medical buildings, as well as office premises where the requirements for plaster are increased. In cross section everything looks like this:
- spray;
- 2 layer;
- 3 layer;
- finishing layer.
The maximum thickness of layers is 20 mm.
Please note! Leveling the walls by applying high-quality or improved wall plaster in accordance with SNiP occurs through beacons that are installed on the wall and serve as a guide for the work as a rule.
They are fixed in advance, before work begins. Metal profiles or the solution itself can be used as beacons.
What is high-quality wall plaster used for?
If the improved plaster is intended for leveling a wall, then the high-quality grade is used both for leveling the walls and for preparing the base for further processing. Which one exactly?
- Application of paints and varnishes.
- Wallpapering.
- Tiling.
- Application of decorative plaster, etc.
Thanks to the quality control specified in SNiP, cladding work can be carried out at the highest level. It is only important to take into account GOST regarding the materials used.
The order of operations is also taken into account:
- first the ceiling is plastered;
- The walls are processed next, from top to bottom;
- Lastly come the floors.
Please note! The mixture is applied to the base in 2 ways: spreading and throwing.
But technology for performing work is not everything. It is important to find out which plaster is best for plastering walls, and what are the requirements of SNiP and GOST for the finishing material.
Required Requirements
To understand which plaster for walls is better, you need to familiarize yourself with the requirements for the material. All of them are described in GOST 28013-98 (clause “mortars”, section “general technical conditions”) and SNiP 3.04.01-87. Here are some of these technical requirements:
- the solution with which the surface will be sprayed and primed should easily seep through a mesh with a cell cross-section of 3 mm. The mixture under the cover should seep through cells with a cross section of 1.5 mm;
- the mobility of the solution should be within 5-12 cm;
- stratification of the solution, no more than 15%;
- the ability to retain water is at least 90%.
As for the plaster itself, it needs to be mixed with sand, the grain fraction of which is 1-2 mm. Solutions for spray primer should not have a sand fraction greater than 2.5 mm and greater than 1.25 for finishing. In addition, the purchased plaster must have a quality certificate and documents indicating: the date of preparation of the mixture, its brand, volume, type of binder, the mobility of the mixture, there is a GOST and the price of 1 m 2 of the solution and its delivery.
It is important to know that plaster for walls can be cement-sand, or maybe gypsum. Cement mortar is used to treat the external walls of a building and wet rooms. If you need to plaster brick walls, it is better to do it with cement mortar.
A mixture of gypsum is used when it is necessary to level walls indoors in which the humidity is normal. The advantage of the mixture is that the work is completed much faster, since it dries faster. You can’t say which one is better, because it all depends on the situation.
The technology for applying high-quality plaster, which is designed to completely level the surface, requires the mandatory use of beacons. Before starting the main work, they are installed on the walls or ceiling. Lighthouses can be in the form of metal structures or from the same mortar that will be used to finish the surface.
After covering with this type of finish, the surface is completely ready for any decoration.
It can be painted, wallpapered, covered with various types of tiles, etc. According to SNiP, minimal deviations are allowed for this plaster. Therefore, facing work is carried out with high quality easily and quickly.
You should pay attention to the order of the procedures. First, it is necessary to plaster the ceiling, only after that the walls are finished, and the direction of the tool should be from top to bottom. The solution can be applied to the surface using two methods. Experienced plasterers can easily spread the mixture onto the walls, but you can just spread it on.
Requirements for high quality finishing
All permissible deviations can be found in the SNiP tables. If you decide to do the work yourself, you need to adhere to these standards. After finishing with plaster, a surface of 4 sq.m. should not have more than 2 uneven outlines, which, moreover, should not be more than 2 millimeters.
But deviations of the slopes of doors and windows, respectively, in the horizontal and vertical directions, are allowed only 1 millimeter. Deviations of curved parts should not exceed 5 millimeters. In this case, experts advise beginners to use templates.
When plastering, the moisture content of the substrates should be approximately 8%. Of course, this is difficult to determine. However, with high humidity, wet spots appear on brick or concrete walls, and mold is sometimes visible. In this case, the base should be allowed to dry thoroughly.
After all the work has been completed, it is necessary to check its quality. To do this, inspect the entire treated surface. According to the requirements, it must be even and smooth, without any damage or marks from tools.
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Material quality requirements
With high-quality plaster, high demands are placed on the quality of the materials used. They are defined by construction GOST and are also given in SNiP. When mixing the mixture for high-quality wall treatment, you must adhere to certain rules. The finished mixture produced in production must also meet all the necessary standards.
So, to carry out such operations as spraying and soil, the plaster composition must be passed through a sieve with a mesh size of 3 mm, and for covering - 1.5 mm. The mobility of the solution ranges from 5 cm to 12 cm. The ability to retain water in high-quality plaster should reach 90%.
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For this plaster it is necessary to use sand with a fraction of 1/2. The mixture used for spraying and priming includes sand, the grains of which do not exceed 2.5 mm, and for coating - up to 1.25 mm. When buying a ready-made mixture in a store, be sure to pay attention to the fact that the appropriate documents are issued with the packaging. They indicate the brand, date of manufacture of the mixture, mobility, substance for the binder, etc.
Improved wall plaster is not a special solution, but a surface finishing method. It is distinguished by improved quality and better operating parameters. This method is often used for interior cladding of buildings.
The solution is well suited for brick or concrete surfaces. The requirements that such coatings must meet are specified in building rules and regulations.
This article will study in detail the technology for applying improved plaster and its main characteristics.
The main differences between improved plaster
A wall finished with improved plaster can be painted immediately It has a number of significant differences from other types:
- The wall surface after this treatment is of better quality. In addition, the wall can be immediately painted or wallpapered.
- According to the standards, the thickness of the layer of such cladding can reach 15 mm, the thickness of simple plaster is 12 mm. Improved cladding is thicker due to an additional layer.
- According to the standards, when facing walls in this way, it is necessary to use construction beacons with the same thickness as the planned finishing layer.
- The errors allowed with improved processing are lower than with simple finishing. Vertical deviations up to 2 mm per 1 m² are permissible. No more than 2 areas with defects are allowed per 4 m².
A comparison table of different types of plaster can be seen below.
Technological features
Spray with liquid solution The stages of working with an improved mixture are the same as when applying other solutions. The first step is to spray the wall, then prime and apply the main layer of plaster. However, there are some differences:
- spraying is carried out with a liquid solution. It is applied to the wall and spread over it; there is no need to level it. In this case, the layer thickness should not be more than 5 mm;
- the soil is made from a thick mixture that looks like dough. Only 1 layer is applied with a thickness of no more than 8 mm. Sand particles in the solution should be no more than 2.5 mm;
- The covering is done in a thin layer of approximately 2 mm. The size of sand granules is no more than 1-2 mm. The density of the solution should be the same as when spraying.
Due to the small thickness of the improved mixture, it can be used for cladding almost any surface, even with complex terrain.
Areas of use
This plaster is used for interior cladding of various types of premises. It is also used for external treatment of various buildings and structures.
There are main areas where this technology is most often used:
- Plastering brick walls and facades from different materials.
- Cladding of various columns and cornices, built from a variety of materials.
- Finishing of surfaces inside the building.
- Processing of small buildings.
Improved wall plaster and the technology for its application are complex, so not every novice builder can do it on their own. The procedure consists of the following steps:
- surface preparation;
- preparing the solution;
- spray;
- padding;
- finishing layer or cover.
Preparing the wall
The technology for performing improved plaster begins with preparatory work. First of all, remove all excess from the wall. Afterwards all minor surface defects are filled
Before proceeding with plastering, it is recommended to treat the wall with a deep penetration primer. This will improve the adhesion of the mixture to the surface. Work continues only after the primer has dried.
Mixing solution ingredients
To improve the quality of the mixture, add PVA glue The facing for such a surface can be made of slaked lime and sand. The ratio of solution to water is 1 to 1.5. When adding sand, use 1 part water, 0.3 parts lime and 3 parts sand.
- The following ingredients are prepared: water, sand and PVA glue. All materials will cost less than purchasing a ready-made solution.
- 20 liters of water are poured into a large container.
- Approximately 200 grams of adhesive is poured out; if necessary, the amount can be increased.
- The composition is mixed.
- Sand and cement are gradually added until the desired consistency of the solution is formed. For more information about applying the improved one, watch this video:
This recipe allows the solution to adhere well to the wall, thanks to the presence of PVA glue in the composition.
Even if the surface is poorly primed, the glue will prevent possible cracking and the mixture coming off the wall.
Also, adding glue will significantly increase the plasticity of the mixture, which will make it easier to apply the plaster solution.
When producing a solution, this recipe allows you to use a larger layer when applying. The maximum permissible thickness increases to 8 cm. In this case, there is no need to use construction material for reinforcement. This factor is extremely important if the walls have a large number of irregularities or when carrying out external work.
Sometimes, instead of cement, gypsum is used to create a solution. To this composition you need to add a small amount of PVA glue. For 10-15 liters of water you need approximately 100-150 grams of glue. This will increase the strength of the composition and its quality.
Spray
The liquid solution fills well all the recesses and cracks in the base Pre-spraying is done with a weak solution.
This is an extremely important nuance, since it is used to prepare for priming.
Due to its liquid state, the solution can easily fill all cracks and recesses. This allows you to create a flat surface for subsequent work.
Spraying must be done carefully so as not to miss any irregularities. Then the result will be a good coating without cracking or coming off the wall.
Application of primer
After spraying, the wall is primed. The solution is applied with a trowel and then leveled with a trowel. You need to hold the tool at a special angle of 150° and perform movements first on the sides, and then from bottom to top. For more information about spraying, watch this video:
The thickness of the soil should vary from 12 to 20 mm. Evenness is checked using a rule. If defects are found, they are sealed with mortar.
To make sure that the primer was applied evenly, the rule is first applied to the wall horizontally, and then vertically and diagonally.
The soil is the main layer, which makes up most of its thickness. It is this material that allows you to finally level the wall, so it is extremely important to carry out this stage according to all the rules.
Final layer
The covering is performed using a special technology. It is applied, leveled, and then rubbed. For such work, you can use a pneumatic bucket or an ordinary brush and grater. Watch this video for more details:
Each layer is leveled with a trowel First, the dried soil is moistened with a small amount of water. Using a brush, cover in several layers. Each layer is leveled using a trowel.
After the mixture dries a little, it is rubbed. To do this, use a wooden grater, and it must be pressed tightly to the surface. Using such a tool, circular movements are first performed, then vertical and horizontal.
The processing procedure is complex and requires skill and experience to complete. If the cladding solution was purchased ready-made, you must carefully follow all instructions from the manufacturer indicated on the packaging.
