What can be the proportions of cement mortar for wall plastering? Plaster mortar: composition and preparation How to knead a mortar for wall plaster

Plaster is the basis before the final decoration of the walls. To date, there is a wide variety of materials from which you can prepare a solution for wall plastering. And here it is worth choosing which composition is better to do with your own hands? In order to avoid bumps and lumps in the preparation of the solution for the wall, you need to follow some rules and proportions, which will be presented in this article.

Solution options

When preparing for leveling walls with plaster, a special mortar should be prepared, which should basically contain two main components: a binder and a filler. Each of them includes various materials, which are freely available in markets and hardware stores. If one of the components is not used, the solution will either be fragile, or will not stick to the wall, or it will not be possible to level it. And with the wrong proportion, you can make an initially even coating, but later, after complete drying, cracks will appear on the wall. The main types of plaster for leveling walls that you can do yourself are:

The first is a solution, which in most cases is used for plastering exterior, facade walls and plinth. That is, the presented type of plastering and its composition is mainly used in places of constant humidity. Inside an apartment or house, great for bathrooms and toilets. If you cook often enough and a lot, then for the kitchen it will also be a good choice.

The second type, presented in the list, is mostly used for external plastering of walls that are not exposed to moisture and humid air.

The third type is suitable for internal walls in all rooms, except those in which the level of humidity is sufficiently high.

The quality of mortars for walls

To get a smooth wall, you need to prepare the right plaster. To get rid of unnecessary lumps, it is recommended to sift all the components through a construction sieve. If this is not done, then after cooking, you can find a heterogeneous mass, and you will have to filter the entire composition with your own hands, this work is not easy and takes a lot of time, so before this process should not be brought. This process is one of the points for creating a quality wall mortar. Other points to highlight include:

Additionally, solutions for plastering walls are distributed according to their fat content. You can meet with high fat content, with normal and so-called skinny.

Plastering process

The normal fat content of the plaster will ultimately lead to an ideal result, that is, the correct selection of all components and consistency. In the presence of increased fat content, after drying, the process of cracking the plastered surface of the walls will occur. Additional defects will be shrinkage and cracking. In the presence of lean, a process of lack of strength occurs, which leads to its falling off when leveling.

Determining the correct preparation of the solution for the walls is quite easy, because apart from it you only need a spatula. The difference is determined by the degree of adhesion of the plaster to the spatula:

Characteristics and composition

Now we choose which composition is suitable for specific purposes.

Lime. Lime dough and sand are used, the composition ratio is 1:3. The dry mixture is mixed with water. With the right consistency, the end result should be like a thick dough.

Lime-cement. To give greater strength, you need to add a tenth of the cement and mix. All lime-based mortars must be prepared and used within 2 days.

Lime-gypsum. The composition ratio is 5:1, water is added and mixed. Take into account the fact of rapid drying - in half an hour you won't be able to work with it. But if everything is done correctly, then the plaster on the wall will be heavy-duty.

Lime-clay. The ratio is prepared 1:1, an additional fifth of the sand is added. It also has high strength.

Clay. First you need to make dough from clay. This is done by adding water. Upon receipt of clay dough, it is mixed with sawdust in a ratio of 1:3. The addition of water and stirring is present in every solution. It has disadvantages in the form of fragility and instability to moisture.

Clay plaster. The proportion and subsequent actions are identical with the lime-gypsum composition. Only here the basis is clay dough.

Cement. It is used to treat walls that are constantly exposed to moisture or steam, regardless of external or internal use. The proportion goes either 1:3, or 1:4 with sand. The property of quick drying allows you to work with it for only 1 hour.

Cement-lime. To prepare it correctly, you should carefully monitor the balance of the composition. Materials used:

There are two ways to prepare such plaster for walls with your own hands:

Modern materials

Today, people began to give preference to special dry mixes, which are produced on the basis of Portland cement and are considered high quality. In addition to the direct basis, they also have special additives that provide the solution with additional characteristics in the form of: increased strength, plasticity. There are a number of benefits that come with such a dry mix that is easy to make. Among them are:

• calm application on the wall without using reinforced mesh which significantly reduces material consumption.
• great elasticity. After drying, it tolerates temperature differences and rapid climate changes.
• passes air through itself and has a fairly strong resistance to moisture.

There are also modified mixes for walls, which were made separately in laboratories. This process was carried out to perfectly match the ratios of all components, which ultimately led to an ideally prepared solution. As an addition, it can be noted that plaster can be made in different volumes, that is, as much as is required at the moment without frills, residues and shortages. On the packaging, sometimes they even write the inscription "pour water and get started."

Now you know the basics, it remains only to choose quality materials to prepare a plaster solution for walls with your own hands and enjoy your work. Watch the video to fix:

Despite the rapid development of the construction industry and the emergence of the latest methods of finishing buildings and structures, none of alternative methods finishes are still not able to compete with traditional wall plastering. This is due undeniable advantages method and its features, as well as the ability of plaster to create a protective finishing layer on the surface of the treated walls, which helps to level the surface and create a decorative cover. With the help of plaster, you can pour the foundation for a building, erect a wall or finish it, and also eliminate existing errors - for all these activities, a plaster solution is needed. However, for each of these areas, different types of plaster are needed - in the process finishing works lime mortar for plastering is required, for masonry walls - masonry mortar. And this is not all the existing varieties of plaster solutions. Building stores offer consumers to purchase a ready-made mixture for the preparation of plaster, surprising consumers with a variety of these products. In order not to doubt the quality of the solution, you can prepare it yourself, while saving a significant amount of money. To get to the bottom of the issue and get acquainted with the different types of plaster mortars and how to prepare them, read our article.

What is plaster? Main Components

Plaster- it's rough facing material, with the help of which the alignment of surfaces of various purposes is carried out - walls, ceilings, foundations. Depending on the style you have chosen for finishing the surface to be treated, various components may be included in the plaster, however, regardless of the purpose of the plaster, the following components must be included in its composition:

• Binder, which increases the adhesive characteristics of the plaster and its fastening properties;
• Filler, designed to relieve internal stress between the particles of the binder components, as well as to increase the volume of the solution;
• Water designed for soaking and mixing constituent parts solution. Masters who do not have sufficient experience in this field do not have a clear idea of ​​\u200b\u200bwhat is the difference between certain types of wall plaster mortar if they consist of the same fundamental components. In addition, there is often an opinion among amateurs that you can get started by mixing cement with sand and water. However, experts assure that it is far from being so simple and offer you the following recommendations.

Depending on the purpose of the plaster, it is customary to add the following components to its composition, each of which plays a certain role and gives the solution additional characteristics:

Lime is added in cases where it is necessary to give the solution additional viscosity. The lime used to prepare the solution can be slaked or quicklime, ground or multi-colored. It is a fragile material with a long drying time, as a result of which lime mortars are used for finishing work exclusively in dry rooms;

Gypsum or alabaster also does not have significant strength, but is characterized by a high solidification rate. It is advisable to use this material for minor finishing measures and as an additional component to lime mortar, which will increase its drying rate;

Cement is a highly durable material that is resistant to weathering and retains its original characteristics after contact with water. Resistance to mechanical stress is another important advantage of cement. Cement-sand mortar based plaster is used for exterior finish walls of buildings, as well as surfaces located in the zone high humidity;

Clay- another component used as an additive to a plaster solution in order to increase its viscosity. Similar formulations are perfect choice for plastering and laying furnaces, due to the fact that after firing, the solution, which contains clay, becomes as strong as possible;

Sand in the composition of the mortar for plaster is used as a filler, due to which the volume of the mixture increases. For solutions intended for various purposes, various types of sand are used, but river sand is the most effective, which is sorted and sieved before being added to the solution.

The main types of mortars for plaster: proportions of ingredients

In accordance with the predominance of certain components, the following types of plaster solutions are distinguished:

• Lime mortar for plaster, to reduce the hardening time of which, gypsum is sometimes used;
• Cement mortar for plaster, with the preparation of which often there are no unnecessary questions;
• Lime-cement mortar for plaster, which includes three components: lime paste, cement and sand;
• Lime-gypsum mortar for plaster, combining optimal viscosity and setting speed;
• Clay mortar for plaster, in which some minor components can be added to give the mixture the required qualities.

Each of these plaster solutions has its own proportions, following which you can create the optimal working mixture.

One of the most popular finishing mixes is lime mortar, which consists of slaked lime soaked in water and sand. The ratio of mass fractions of these components looks like 1: 2, less often to 5;

Cement mortar for plaster consists of cement and sand, with a ratio of mass fractions as 1: 3 (4). To prepare the solution, the resulting dry mixture is poured with water;

For cooking cement-lime mortar you will need cement and sand, taken in a ratio of 1: 3 (4), as well as a lime suspension, which is slaked lime diluted with water to the consistency of milk;

Lime-gypsum mortar for plaster is a common lime mortar, consisting of a mixture of sand and slaked lime, as well as gypsum. The ratio of the mixture of lime and sand to gypsum is 1:0.3;

Clay solutions for plaster, most often prepared with the addition of minor ingredients such as cement, sand, gypsum or lime. The choice of one or another component depends on the subsequent use of the solution. Approximate ratios of components in clay mortars for plaster are as follows:

• Clay and sand in a ratio of 1:2 (5), which depends on the viscosity of the clay;
• Clay, lime and sand in a ratio of 1: 0.3: 4.

To prepare the solution, you will need to add water to the dry mixture, the volume of which depends on the required viscosity of the solution.

Important! Before you start preparing the solution, you need to make sure that you need to use this particular mixture. For the greatest reliability, it is necessary to estimate physiochemical properties solutions and where to use them. In case of an incorrect choice of the component composition, this may cause a decrease in performance characteristics treated surface.

Thus, the choice of ingredients depends on:

• Type of work (mortar for external plaster must be resistant to high humidity);
• External conditions under which the operation of a building or premises is carried out. These include: temperature, humidity, the presence of aggressive external factors;
• The material from which the surface to be plastered is made.

Varieties of plaster depending on the proportion of ingredients:

Taking into account the proportions of the fundamental components, the plaster mortar can be divided into three types:

• Grease solution, in which the binding component predominates. After drying, such a solution is prone to cracking;
• normal solution, characterized by an optimal ratio of filler and binder;
• Lean mortar, which is not typical a large number of filler, and therefore, it is short-lived and fragile.

To determine the type of mortar, you only need a trowel and a little observation. Dip it in the solution and see:

• If the solution sticks to the trowel in pieces, the solution is greasy;
• If the trowel is only slightly dirty, the mortar is thin;
• If the solution lay on the trowel in the form of a thin crust, the ratio of binder and filler is normal.

Important! You can reduce the fat content of a solution by adding a filler to it, while increasing the viscosity of a lean solution can be done by adding a binder.

The composition of the mortar for plaster: general requirements

What to look for when choosing the composition of the mortar for plaster? First of all, it is important to follow the following points:

• To plaster concrete and stone facades that are under constant exposure to moisture and precipitation, experts recommend using Portland cement and Portland slag cement to prepare a plaster solution;
• If stone and concrete facades are not constantly exposed to moisture, it is recommended to use mortars for their plastering, which are based on the use of lime and cement, as well as other lime-based binders;
• For finishing wooden and gypsum surfaces, lime mortars are used, in which it is recommended to include alabaster to increase the rate of solidification of the mortar;
• Solution for internal plastering of rooms with high humidity (humidity level during operation is above 60%, which is typical for kitchens, bathrooms or baths), the first layer is applied from a cement or cement-lime mortar.

Decorative characteristics of the mortar for plaster: what to look for?

Often, experts recommend paying attention to decorative mortars for plaster, which can be used both for interior decoration walls of the room, and for finishing facades. In the process of making decorative mortars, it is recommended to use the following substances as a binder:

• Traditional, white and colored Portland cement for interior facades and walls;
• Gypsum and lime intended for colored plastering of indoor walls.
• In the process of making decorative mortars, the use of marble, granite, dolomite, tuff and various fractions of limestone is widely practiced;

Important! To enhance the gloss of the plaster composition, no more than 10% crushed glass and 1% mica are added to its composition. It is also practiced to add dyes - alkali-resistant and light-resistant pigments of natural origin, such as chromium oxide, ultramarine, ocher, iron red lead and other well-known substances.

How to make a mortar for plaster: preparatory measures

First of all, it is necessary to prepare a container for mixing the solution, the volume of which depends on the required amount of solution. Experts recommend giving preference to such a container, the configuration of which will provide a complete sample of the solution. In the event that the container is characterized by a complex configuration, the solution will solidify in the bottom and in the corners of the container, which will subsequently lead to difficulties in subsequent attempts to knead the solution. Experts recommend choosing containers with a large bottom of the pallet, and therefore, it is not recommended to use a bucket as a container for mixing the solution.

In addition to the container, it is necessary to prepare the following materials and tools:

• A dispenser, which can be used as any container of arbitrary volume;
• Nozzle for a drill (the so-called mixer), designed to mix the components of the solution. If you do not have a drill attachment, you can mix the mortar manually using a trowel or other handy tool;
• Binder (clay, lime or cement);
• Filler (sawdust or sand);
• Water.

Preparing a mortar for plaster: a step-by-step guide

Before answering the question: "How to make a mortar for plastering walls?", It must be answered that the preparation of the mortar is carried out in several stages, the first of which involves the preparation of a dry working mixture, and the second - the addition of water to it and the actual mixing of the mortar. There are two ways to prepare a mortar for plaster: manual and mechanized.

Manual method of preparing plaster

It involves mixing a dry binder, during which the following rules must be observed:

• The first and important requirement is the capacity requirement. Its bottom should be flat and clean;
• Sand is poured into the bottom of the container in the form of a continuous layer or in the form of small piles;
• The binder is distributed evenly over the sand layer;
• The mixture is stirred and leveled with a rake;
• The last two points must be repeated several times.

Important! If the mixture is not sufficiently mixed, its color will be characterized by heterogeneity and the presence of stripes, while the criterion for high-quality mixing of the composition will be its uniformity.

Mechanized way of preparing plaster

To save time and effort, a drill attachment or a so-called mixer is used to mix the solution. For a mechanized method of preparing a mortar for plaster, the consumption of which largely depends on its composition and quality characteristics, you will also need a bucket or any container that replaces it. Fall asleep in it necessary components in the right proportions, depending on the type of solution chosen, and using a mixer, mix it until a homogeneous consistency.

How to prepare a cement-lime mortar for three-layer plaster?

The most common practice at construction sites is the use of cement-lime mortar. They are intended for installation of external and internal three-layer plasters. In order to properly prepare such a solution, it is necessary to know the requirements for the composition and consistency of each of the three layers, as well as their other specific features.

The first layer of plaster is sprayed. Its application is carried out on a previously prepared surface so that all the pores of the treated surface are filled. The application of this layer is carried out in order to increase the adhesive characteristics of the treated surface, that is, to increase the adhesion strength of the base to the plaster layer;

Important! The solution intended for spraying should be of an appropriate, creamy consistency. The thickness of the application of the solution on the ceiling does not exceed 4 mm, on the walls 3-4 mm. The solution for spraying can only be prepared with cement without the addition of lime, however, if you are working in rooms with high humidity, you need to prepare a cement-lime mortar.

The second layer of plaster is soil. The thickness of this layer should not exceed 15 mm, and its application is carried out only after the first layer - the spray begins to set, but has not yet completely hardened. The solution intended for the soil should be of the appropriate consistency, reminiscent of tough dough. The middle layer of plaster is leveled with a trowel or rail, but in order to ensure a more comfortable application of the final plaster layer, experts recommend leaving some roughness and unevenness on the ground;

The final finishing layer - nakryvka. To prepare the solution applied at this stage, fine sand is used. At the same time, lime is added to it, and in a larger amount than in the previous stage. Thanks to this trick, the solution acquires a more plastic consistency. The covering layer is applied in a thin layer (no more than 3 mm), after which it is carefully leveled with a trowel or trowel.

Most reliable way, with which you can qualitatively level the walls, this is plastering. Plaster allows you to prepare the base of the outer and inner walls for finishing. Previously, to prepare a solution for plastering walls with your own hands, classic ingredients were used mixed with water in the correct proportion. It was only cement and sand.

The modern market of construction and finishing materials full of ready-made mixtures that only need to be diluted with water. However, the rules for mixing the mortar will vary depending on the composition of the plaster. How do cement, clay and lime mortars differ from each other, and how to mix them correctly?

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The composition of the plaster

Each plaster solution has its own components, mixed in various proportions:

• clay and sand in a ratio of 1 to 2 (5) - the number of shares of sand depends on how viscous the clay turned out;
• a solution consisting of three components - clay, lime and sand - is mixed in a ratio of 1: 0.4: 4;
• clay, cement and sand plaster is mixed in a ratio of 1:0.3:4.

All of the listed types of plasters are mixed with water, the amount of liquid directly depends on what viscosity you need.

What is required for work

To mix different plaster compositions, you will need one or more binders (cement, lime, clay or gypsum), filler (most often this role is played by sand) and water. When mixing all the components, you should be guided by the exact ratio of the proportions of the composition. However, this is not the only thing to consider: the quality of the plaster is affected by such a concept as fat content. Most often this applies to lime and clay plasters.

In this case, the concept of "fat content" is in no way connected with its literal meaning: it is a parameter by which the amount of the binder component is determined - sufficient or excessive. By fat content, plaster compositions are divided into three types - fatty, normal and skinny.

• The disadvantage of greasy plaster is that it shrinks too much when it dries, which leads to cracks in the surface.
• Too lean mortar is also covered with cracks, but for a different reason - it does not adhere well to the surface and gradually begins to move away from the base.

It is difficult to determine the level of fat content of plaster by eye; this requires some experience. When kneading the composition, check how strongly the plaster sticks to the tool. The stronger the solution sticks, the greasy the plaster, but skinny plaster, on the contrary, will stick very poorly or not at all.

cement mortar

To properly prepare the plaster composition from cement, you need to perform several stages of work:

1. First of all, the sand is dried and sifted until there is not a single lump left in it. Important: reddish sand should not be added to the plaster, as it is of poor quality. If you do not want to bother with sifting, you can use quarry sand, it is already clean and crumbly.
2. Second and final stage- mixing. into container right size pour cement and sand in a ratio of 1 to 4 and mix thoroughly. To avoid the appearance of lumps, pour water into the composition gradually. However, such plaster will be extremely difficult to stir on your own if you need too much mortar. For such volumes, you will have to rent a concrete mixer.
   
   Important: to obtain high quality plaster, you must use cement not lower than M400. With the use of cheaper and lower quality cement, the walls will simply crumble.

   Lime mortar for walls

   
   

   Making such a plaster is somewhat more difficult than a classic cement mortar. Lime plaster hardens much more slowly, so you have to resort to some tricks.
   Important: only slaked lime is suitable for the preparation of lime mortar.
   Stages of work:

   1. Grind the lime so that in the end there is a homogeneous mass without lumps.
   2. Pour sand in proportions of 3 to 1 in relation to lime.
   3. Thoroughly mix the dry plaster and begin to gradually pour in water until a solution of the desired density is obtained. Ready plaster should not be stored for longer than a day - it will be unsuitable for further use.
   4. In order for lime plaster to harden faster and have better adhesion, a little gypsum should be added to it. But in this case, it is better to stir the composition in small quantities, since it will harden very quickly - almost instantly after application.

   Important: do not overdo it with the amount of water. Too much liquid will only worsen the quality of the plaster.

   Clay plaster mortar

   
   

   No less than lime and cement, natural clay is also used. The main thing is not to buy liquid clay for plastering, because it will eventually slide down from the wall. To make a solution of high quality, you will need a large number of ingredients - clay, sand, cement and lime. Stages of preparation:

   1. Soak the clay in water for 6 hours and refill regularly new water as soon as you see that upper layer began to dry up. You should get clay of medium density.
   2. Pour pre-sifted or quarry sand in a ratio of 2 to 1. Sometimes the amount of sand needs to be increased to four parts.
   3. To strengthen the mortar, add 0.2 parts of cement and mix well.

   Not all plaster solutions are suitable for outdoor use, some are used only for interior wall decoration. The technology of using mixtures depends on their composition.

   Where is plaster used?

   
   

   Depending on the climate, the level of humidity, the place where the plaster is applied, different solutions are used:

   • Lime and lime-gypsum plasters are best suited for leveling indoor surfaces. Such walls turn out to be literally "breathing" - depending on the change in the level of humidity, they either store moisture or give it back. As a result, the microclimate in the room is constantly regulated and maintained in the normal range.
   • Cement-sand plaster is used for exterior finishing work, and is also used in rooms with too high humidity - in the kitchen, bathroom, bath, etc. Such plaster not only levels the surface of the outer walls, but also holds them together, making them stronger . Cement-sand mortars are used for finishing stone fences and garages.
   • Pure lime plaster is well suited for window slope treatment, it is much more effective than cement plaster, because it has best parameters thermal insulation. For example: the thermal conductivity of lime plaster and cement plaster is 0.86 and 1.3, respectively.
   • Clay plaster is often used to decorate stoves, pipes and fireplaces. At the same time, the nearest space around the furnace is plastered with a clay-sand composition, and the thermal surfaces are plastered with a solution of clay and lime.

   Surface preparation for plastering

   
   

   Plaster of any type should be applied only on a previously prepared base, otherwise the results of the work will not please you - the plaster will fall off the wall or ceiling along with the decorative coating.

   • In brickwork, all protrusions from the joints must be removed, and the bricks themselves must be completely cleaned of dust, dirt and cement residues.
   • Before starting work, notches must be applied to the surface of building blocks.
   • If earlier there was already plaster on the base, it must be completely beaten off or only the top layer should be removed - depending on the condition of the coating.

   Calculation of plaster consumption

   Before starting work, it is important to know exactly how much plaster is needed - this will help save money by avoiding overspending of the material. There are two main factors that are important to consider when calculating the volume of plaster:

   • Curved walls. If it so happened that the walls in the same room are different in length and width (and this is not uncommon, for example, in panel houses), they must be leveled, which will require a much larger amount of plaster. It will also be necessary to increase the volume of the mixture if there is a need to close cracks and potholes.
   • The composition of the plaster itself. Since different mixtures have their own consistency, the consumption per 1 sq. meter will be different.

   Method for calculating plaster

   First of all, you need to determine the required coating thickness. You should first prepare the base by removing all parts that are loose or crumble. When the wall is ready, use a laser level and determine the level by placing beacons around the perimeter of the room. If there is no laser, use a weight (an ordinary washer will do) on a strong thread. Next, measure the degree of deviation from the resulting line at 4 points, add the resulting data and divide by 4.

   
   
   Standard plaster mixes are based on a layer of 1 cm per 1 sq. meter. It is enough to calculate the area of ​​\u200b\u200bthe walls that require plastering. Multiply the resulting dimensions by the average thickness of the plaster calculated earlier. At the same time, always buy mixtures with a small margin, since the actual consumption of plaster may differ from what you counted. Get a couple of packs more, but no more.
   Some features of plaster mixtures:

   1. The lime composition is warmer and practically not susceptible to the appearance of mold and fungi.
   2. Cement plasters are moisture resistant and have great strength.
   3. Gypsum in the composition of lime mortars increases their strength and quality of adhesion to the surface, but greatly reduces the time of use.
   4. Clay plaster mortars are the least durable of all, but they perfectly withstand very high temperatures.

   When carrying out finishing work, outdoor or indoor, be guided by the choice of plaster based on the highest priority qualities. Then the plaster will last a very long time, and over time there will be no surprises in the form of cracks or crumbling walls.
   

Plastering walls is no easy task. It directly affects the quality finishing walls. If you decide to do this work with your own hands, then we will tell you how to prepare a mortar for plaster, the proportions in which must be strictly observed. Otherwise, you can get not a smooth, even and durable surface, but a loose, porous layer of mortar, ready to fall off at any moment.

In the article we will answer questions about the composition and proportions of the mixture based on various components, we will talk about the requirements for mortars for plaster, as well as about the types of various modifying additives.

Buy ready mix or make your own

In this matter, the main role is played by the finishing area, as well as the physical and financial capabilities of the owners.

• Ready plaster mix.

The composition, in addition to the main selected and high-quality components (cement, sand), includes many special additives - modifiers, plasticizers that improve the working and operational qualities of the plaster.

But the price of such a mixture is much higher than that of a do-it-yourself solution. Therefore, it is unprofitable to use ready-made plaster on a large area. But if you need to finish a small surface, then it is better to purchase a ready-made composition. You don’t have to buy all the components separately, charge the mortar mixer, and it will take less time.

• Do-it-yourself plaster mixture.

When you have to finish a large brick or foam block house, then to reduce the cost of work, the owners usually prefer to prepare the plaster mixture on their own. Cement, sand are bought, a small mortar mixer is installed, and little by little, in portions, a solution is prepared.

In this case, you have to work with your hands and spend some amount of personal time. But as they say, "your work does not count."

At independent work it is necessary to strictly observe the proportions of the mortar for wall plastering, otherwise there is a risk of reworking the entire work already at the application stage. Even worse, if a low-quality solution begins to fall off at the stage of finishing, fine finishing.

It is possible to correct such a marriage only with the complete removal of the applied plaster and replacing it with a new layer. And this, as you know, additional and considerable expenses.

Types of cement mortar, requirements, proportions

There are few types of mixtures, but each requires separate consideration, as it has its own unique characteristics. They differ in the presence of various additional components in the solution.

So, the plaster mixture can be:

Used for leveling and finishing. Such a mixture is compatible with any rough surfaces, except for concrete, due to weak adhesion to the latter.

This mixture is mainly used for rough plaster; for finishing, sand of a very fine fraction is needed. The mixture remains "alive" for an hour, after which technical specifications get worse.

• Lime-cement.

Used for finishing brick or concrete surfaces. Lime gives the solution plasticity, which facilitates its application and stretching. It also increases the vapor permeability and strength of the solution, extends the "survivability" of the mixture up to 3 hours.

In addition, lime has bactericidal properties, on walls covered with lime mortar, mold will never form, fungus and microorganisms will not appear. But the proportions of lime mortar for plaster must be observed in order to avoid lime stains on the walls.

Lime "efflorescence" will bring a lot of trouble when finishing, since not all paints or putties are compatible with this material.

• Gypsum-cement.

It is applied to the improved plaster of walls. Gives an even, durable layer that can be easily sanded. It sets quickly, so it is not recommended to prepare a large amount of solution at once.

If it is necessary to prepare a lot of mortar, then setting retarders are used to extend the "life" of the plaster mixture. They are already present in ready-made mixtures.

Important! In mixtures prepared independently, depending on the air temperature, the type and quality of the surface, the type of room, it is necessary to add special components. Properly selected mineral fillers, polymeric additives or plasticizers will make the solution more plastic, frost- or heat-resistant, enhance adhesive and astringent properties.

Cement-sand and lime mortars are used for interior or exterior walls (see How exterior walls are plastered) exposed to moisture, gypsum-cement mixtures are used only for internal works in dry rooms.

Requirements for the components of the solution

The composition of any plaster solution includes three main components: cement, sand and water. The strength and durability of the applied layer, as well as the quality of grinding and subsequent finishing, directly depend on their quality.

So:

1. Cement.

• This is a binder component that plays a major role in the formation and hardening of the solution, giving the mixture strength and water resistance.
• The proportions for the preparation of the plaster mortar are standard. it is recommended to use Portland cement or Portland slag cement at least M300.
• It depends on the brand what proportions of cement and sand for plastering will need to be taken: the higher the brand, the more parts of sand need to be added per unit of cement.
• This material also has a shelf life, the fresher the cement, the better performance. It is advisable to purchase it in paper bags and store it in a dry place.

Cement is not afraid of frost, but from high humidity, the hardening process can begin right in the package.

1. Sand.

This material is the filler of the plaster mixture, it determines the strength, weight, thermal conductivity and density of the solution.

• When interacting with cement, sand creates a monolithic layer with the properties of solid rock.
• For rough plaster, fine-grained ravine sand is taken, in which a small presence of clay is allowed.
• If there is a lot of impurities, then the solution is able to settle and delaminate. It will have to be constantly mixed, and it is still difficult to work with it, as the ability of the mixture to stick and level is reduced.

For an improved layer, river sand is best - or ordinary, but clean, sifted through a fine sieve, washed from impurities. And again, we must not forget about the proportions - cement-lime plaster will turn out to be of higher quality if the sand in it does not contain clay impurities, and the amount of filler does not exceed the required volume.

1. Water.

• The liquid for the solution must be clean, free of oil impurities, various organic and chemical contaminants, debris.
• All impurities after evaporation of the liquid will remain in solution and can significantly affect the quality of further finishing.
• Oil stains will show through the plaster or wallpaper, the paint will peel off in this place. The same can happen from the presence of chemical impurities. Therefore, experts recommend using clean, better drinking water.
• When mixing with water, the cement setting process begins in the plaster mixture, therefore, after kneading, the solution must be worked out within 1 hour.

Longer storage of the mixture reduces specifications material, and complicates the work.

Proportions of components for different types of solution

Any instruction requires strictly observing the proportions of cement and sand for wall plastering, so that the work is quick and pleasant, and the result is pleasing with strength and reliability.

If there are no plasticizing additives, then to improve the plastic properties of the solution, the masters advise adding a little neutral liquid soap or soap solution:

• In the cement-sand mixture, the composition of the main components should be as follows:

Water is added to the mixture gradually, with constant stirring. The solution is brought to the consistency of thick sour cream.

Important! Too plastic mortar will lie unevenly on the wall, drain, and when leveled, it will reach for the tool. A hard mixture will stick to the trowel, making it difficult to throw it on, and when it dries, it will shrink and crack. You can recognize a normal solution by immersing a trowel, the mixture should leave a thin layer on it without adhering lumps.

• Lime mortar for plaster, proportions:

When cement-lime plaster is used in the decoration, the proportions of lime in the composition of the solution are small, so it is better to purchase ready-made lime paste at a hardware store. It is rather problematic to prepare the necessary component with your own hands, the term for slaking and aging lime is about a month using a special technology.

An improperly prepared or unripened mass can destroy the plaster mortar and nullify all work.

Modifying additives

Separately, it is necessary to talk about additives in the plaster mortar, with them the mixture will acquire some important properties necessary both for applying and treating surfaces, and for their further operation.

Here, too, it is important to maintain proportions for wall plaster: each package has detailed instructions on the use of the additive, and it must be strictly followed:

• Setting accelerators or retarders.

These are components that act on the crystal lattice of the binder and regulate the time of its formation (setting).

It is desirable to make them, for example, in a gypsum-cement mixture to extend its "survivability". In this case, casein or bone glue serves as such an additive.

• Additives to increase plasticity.

These substances, getting into the solution with water, form a lot of bubbles, due to which the liquid evaporates less and is absorbed into the surface, which means it stays in the mixture much longer. They are recommended for simple, traditional cement-sand mortars which quickly lose water and exfoliate.

• Antifreeze additives.

Basically, it includes various special salts that slow down and even exclude for some time the freezing of water in solution, which means they reduce the risk of loss positive qualities mixture as the temperature drops.

I must say that they operate mainly up to -5 degrees. At a lower temperature, plastering work cannot be carried out, here no additives will save the mixture from freezing.

• Strength additives.

They can be of two types: some work in tandem with a binder, by means of chemical action they increase its properties; others act independently, personally perform a reinforcing function.

The second type is called fiber, which may consist of waste glass, pulp or metal production. Fiber is sold in the form of small chips or polymer threads, which, getting into the solution, intertwine and give the plaster additional strength.

Conclusion

If the surface of the walls turned out to be not too smooth, do not be upset - all the small irregularities will be hidden by the finishing putty. The main thing is that the plaster itself is strong, does not crumble, does not crack and does not fall off.

By correctly determining the composition and calculating the proportions of the plaster, you will get a high-quality and durable coating that will not require repairs for many years. And after looking at the photos and videos in this article, you will get answers to other questions that concern you.

But if you are still not confident in your abilities, and do not risk plastering the walls yourself, then we recommend inviting specialists who will do this work quickly, beautifully and efficiently.

Plaster is an integral part of the finishing of walls and ceilings. How long we do not need cosmetic repairs depends on its quality. The quality of the plaster mixture itself, and then the plaster coating, depends on the composition.

Cement plaster mixes

Cement plaster mixtures can be divided into two types:

• Cement-sand, used for leveling and finishing any surfaces, except for concrete. Adhesion with such a base for cement plaster is poor.
• Cement-lime, used in the decoration of brick, concrete and ceramic surfaces

Both plaster compositions necessarily include special polymer additives and mineral fillers, which make the finished mixture more plastic, heat and frost resistant, and enhance its astringent and adhesive properties.

We prepare plaster

You can make a plaster mortar from a ready-made mixture, or you can do it yourself. Part cement mortar add sand of medium fraction and a little liquid soap, which prolongs the time of work with the solution.

Below are the proportions of cement mortar for plaster. The composition of the cement-sand mixture:

• 1 part cement;
• 3 parts sand;
• water to the consistency of thick sour cream;
• liquid soap

The composition of the cement-lime mixture:

• 1 part cement;
• 3 - 5 parts of sand;
• 1 part lime dough (one part quicklime + three parts water. Pour lime warm water, wait for the reaction to begin, add more water and mix. Close and let ripen for one day. Then dilute with water to liquid state, pour into the prepared pit, after a day we pour sifted sand on top, and on top of the ground. The maximum layer of sand and earth is half a meter. Lime is aged in the pit for 15 to 20 days, at the end of this period lime dough is obtained, which is used in the preparation of plaster cement-lime mortar.);
• liquid soap or soap solution.

The preparation of a cement mortar for plaster consists in mixing sand and cement in the required proportions. The resulting dry mixture is gradually poured either into water or milk of lime, add liquid soap. By appointment, we adjust the amount of liquid - for spraying walls, a weaker solution is required, for rough plastering of walls after spraying - a thicker one.

To prepare a cement mortar for wall plastering, it is enough to know the exact proportions of cement, filler and liquid, as well as follow simple rules.

1. We take a clean box with a flat, smooth bottom.
2. We pour clean sifted sand to the bottom.
3. Pour cement on top.
4. Thoroughly mix the dry mixture, then level it with a rake.
5. We repeat point 4 several times.
6. We carefully look at the finished mixture, it should be a uniform color.

Advice. Prepare the working mixture in small quantities. After forty to fifty minutes, it will seize and begin to lose its properties, and the coating will turn out to be of poor quality.

There are three types of ready-made plaster mixes prepared from factory dry ones. Their quality is determined by the trowel lowered into the container with the finished mixture.

1. Fatty. Too sticky, strongly sticks to the trowel. As it dries, it will crack and shrink. We adjust the ratio of the finished mixture and the filler, adding it and stirring thoroughly until we get the desired consistency.
2. Normal. A thin layer of cement mortar remains on the trowel.
3. Skinny. The presence of the mixture is barely noticeable on the trowel. In this case, the ratio of dry mix and liquid must be corrected towards cement by adding it and stirring thoroughly.

In the photo in this article you can see how to properly knead the solution.

Advice. When preparing this kind of mixture for plaster, use only slaked lime. Quicklime, when water is added, will enter into an uncontrolled reaction with it and it is not a fact that it will be completely extinguished. In the future, the remaining pieces of unslaked lime will come into contact with moisture, which will lead to gaps in the plaster coating.

Plaster mixtures, where there is little cement and too much sand, have little plasticity and are very inconvenient to use, therefore the optimal ratio of cement and sand is 1: 3. We use cement brand M400, it gives the best result.

Application of cement plasters

Cement-based plaster mixtures are considered universal, as they can be used for both indoor and outdoor work, they are resistant to moisture, and have good vapor permeability. You need to know that such a mixture dries for about 4 weeks. But it must be processed no later than an hour after application.

Advice. The layer of plaster on the outer walls of the building should be twice as thin as on the inner ones. Thus, the normal vapor permeability of the walls is observed, fungus does not form on them and condensate does not collect.

In addition to the correct composition and kneading of the plaster mixture, it is necessary to properly prepare the base, otherwise all the work will go down the drain and everything will have to be started anew.

Here are some tips for preparing the base (using a brick wall as an example).

1. It is necessary to level the surface and peel off the dried cement (if any).
2. Then carefully sew the seams brickwork(if there are any voids and recesses - leave as is).
3. We remove dust, if there are greasy stains - wash them off, wipe the surface with a damp sponge and let dry.
4. We cover the base with a primer and let it dry.
5. We prepare the mixture for plaster and proceed to the application. We work from the bottom up and from right to left.
6. After about 40 minutes, we proceed to the final alignment.

Advice. It is not recommended to work at temperatures above + 25 and below +5 degrees, as well as in rainy weather. If you still had to plaster in hot weather, it is recommended to moisten the finished surface regularly to avoid premature drying and cracking.

Starting to repair, you need to decide for yourself how much effort you are willing to spend on it. Maybe for you best solution there will be a purchase of ready-made cement mixtures from well-known manufacturers.