How to make a mortar for plaster: preparatory measures. Mortar for plastering Mortars for external plastering

Despite the rapid development of the construction industry and the emergence of the latest methods of finishing buildings and structures, none of the alternative finishing methods is still able to compete with traditional wall plastering. This is due to the undoubted advantages of the method and its features, as well as the ability of the 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, build a wall or finish it, and eliminate existing errors - all these activities require a plaster solution. However, for each of these areas, different types of plaster are needed - in the process of finishing work, lime mortar for plaster will be required, for laying the wall - 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.

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

What is plaster? Main Components

Plaster is a rough facing material, with the help of which surfaces of various purposes are leveled - 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:

• A binder that increases the adhesive characteristics of the plaster and its fastening properties;
• A filler designed to relieve internal stress between the particles of the binder components, as well as to increase the volume of the solution;
• Water intended for soaking and mixing the components of the 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 hardening 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 high-strength, weather-resistant material that retains its original characteristics after contact with water. Resistance to mechanical stress is another important advantage of cement. Plaster based on cement-sand mortar is used for exterior decoration of walls of buildings, as well as surfaces located in a zone of high humidity;

Clay is another component used as an additive to plaster mortar to increase its viscosity. Such compositions are an ideal 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;

To prepare a cement-lime mortar, cement and sand are required, 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 mortars for plaster are 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 required to evaluate the physicochemical properties of the solution and the place of their use. In case of an incorrect choice of the component composition, this may cause a decrease in the performance characteristics of the 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:

• A greasy solution, in which the binding component predominates. After drying, such a solution is prone to cracking;
• Normal solution, characterized by the optimal ratio of filler and binder;
• Lean mortar, which is characterized by a small amount 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 solutions 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;
• Mortar 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 solutions for plaster, which can be used both for interior decoration of the walls of a 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 minium 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 is 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 most 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. The necessary components are poured into it in the required 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 most reliable way with which you can qualitatively level the walls 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 for building and finishing materials is 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. The second and last step is mixing. Pour cement and sand in a ratio of 1 to 4 into a container of a suitable size 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 add new water regularly as soon as you see that the top layer has begun to dry out. 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 processing window slopes, it is much more effective than cement plaster, since it has better thermal insulation parameters. 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.
   

The main purpose of plaster is to prepare surfaces for finishing, that is, to eliminate defects and level walls. In addition, the plaster mixture can act as a decorative coating, depending on the components and application technique. How to prepare a solution for plastering walls, how to calculate its amount and apply it correctly, as well as some of the nuances of this process, will be discussed.

Any plaster solution includes three main components - binder, water and filler. Cement, clay, lime and gypsum act as a binder, and they are often combined with each other in various proportions. The filler is most often ordinary sand, but in ready-made factory mixtures it can be replaced with quartz and perlite sand, marble and granite flour, stone chips. Additionally, the plaster mixtures include modifying additives - coloring pigments, plasticizers and others.

Depending on the type of binder, there are several types of plaster compositions:

• cement;
• clay;
• calcareous;
• plaster;
• cement-lime;
• cement-clay;
• clay-lime;
• lime-gypsum.

Mixtures with two or three binders are called complex. In addition to the composition, the ratio of components also plays an important role - based on this, the solutions are divided into fatty, lean and normal.

Fat is considered a solution with a predominance of the binder component. In the process of drying, such plaster shrinks and cracks, as a result, repeated processing of the walls is required. It is not difficult to determine the fat content of the working mixture: when mixed, it sticks to the trowel and remains on the walls of the container in a thick layer.

If there is an excess of filler in the mixture, this is a lean solution. It almost does not shrink, does not crack after drying, but does not adhere well to the surface and has too low strength. It is enough to lightly hit the wall so that such plaster falls off. With stirring, the lean solution easily slides off the trowel, leaving almost no trace.

A normal solution is moderately plastic, it is easy to interfere, and if you put a little mass on a trowel and let it slide, a thin uniform layer will remain on the surface. It is this composition that provides maximum adhesion to the treated surface and creates a durable, reliable coating.

Popular ready mixes

Prices for popular types of plaster

Plaster

Do-it-yourself proportions for preparing solutions

Each type of mortar has its own characteristics, which must be taken into account when choosing a plaster composition for finishing the facade.

The indicated proportions may vary slightly depending on the moisture content of the sand, the viscosity of the clay and lime paste, and the air temperature. Sand for kneading must be sieved to remove foreign particles. The clay must also be clean, free of grass residues, pebbles or earth impurities. All this reduces the quality of the plaster. Ready-made factory mixtures have a balanced composition, you do not need to add anything to them except water. The proportions of the dry mixture and water are always indicated on the packaging, so read the instructions before preparing the solution.

Calculation of the amount of plaster mixture

Before proceeding directly to the batch, you need to calculate the required amount of solution. As you know, the unworked storage solution is unsuitable, and it remains only to throw it away, which means that part of the money will be wasted. How to avoid unnecessary costs, consider in more detail.

The greatest difficulty in the calculations is the curvature of the walls. It is impossible to achieve a perfectly flat surface during the construction of a house, and it is good if the deviations do not exceed 10 mm. But, as practice shows, very often the differences are from 1 to 5 cm, and in some cases even more. When plastering the whole house, calculations must be performed for each wall separately. First you need to determine the average thickness of the plaster layer.

Step 1. The surface of the wall is thoroughly cleaned of the old finish, all noticeable tubercles are knocked down, the influx of mortar, if necessary, clears the seams.

Deep grooves and cracks in the wall are sealed separately with cement mortar and allowed to dry well.

In a small container, alabaster is diluted with water to the state of a thick slurry, then a level is applied to the wall, a vertical is determined and a solution is thrown along this line at 3-4 points.

A beacon is applied, pressing into the solution, and its location is checked by level. If necessary, press in more or add alabaster. In the same way, other beacons are fixed in increments of 1.5 meters along the wall.

Some builders use special beacon fasteners with dowels instead of mortar, but for this it will be necessary to first make markings on the wall and then drill holes along the lines. The solution is easier and faster to work with.

Step 3 The width of the gaps between the wall and the beacons is measured, and then everything is summed up and divided by the number of beacons.

For example, at one point the gap is 2 cm, at another 3.5 cm, in the third place it is generally 5 cm. The more measurements you take, the more accurate the result will be, so measure the deviations under each beacon at several points. Let's say a total of 30 cm is obtained, and 10 beacons are installed. We divide 30 by 10 and get 3 cm - this is the average thickness of the plaster layer required to calculate the amount of mortar.

Step 4 Now we find out the total volume of the plaster mixture: for this, we multiply the surface area by the layer thickness. For example, the width of the wall is 4.5 m, the height is 2.5 m, the thickness of the plaster layer is 30 mm (0.03 m).

5x2.5x0.03= 0.3375 m3

We round up and get about 340 liters of solution. With a ratio of 1:3, the volume of cement is approximately 112 liters, or 0.1125 m3. The average bulk density of cement is 1500 kg / m3, therefore, by multiplying the volume by the density index, we find out the approximate weight of the material: 0.1125x1500 = 168.75 kg.

Since cement is packaged in 50 and 25 kg bags, you will need to buy 3 large bags and 1 small bag, or 7 bags of 25 kg. Similarly, the weight of sand, gypsum, lime and other materials is calculated.

When using factory mixtures, it is easier to perform calculations. The packaging indicates the consumption of the composition per square meter at a certain layer thickness. If this thickness matches the one you got, you just need to multiply the indicated consumption by the area of ​​\u200b\u200bthe working surface. If it does not match, multiply the consumption by the area and by the layer thickness.

For example: on the packaging of the Weber Vetonit mixture, the consumption is indicated as 2.5 kg / m2 with an application thickness of 2 mm. Our calculated thickness is 30 mm, that is, 15 times more. We calculate how much mixture is needed per 1 square meter:

2.5x15=37.5 kg/m2

Let's say the wall area is 10 m2, then the plaster will need 375 kg (37.5x10). The standard packing is 20 kg, so we divide 375 by 20 and get 18.75 bags. This means that for plastering you need to buy 19 bags of mix.

Solution preparation technology

Cement-sand mortar

Cement plaster is considered the best option for finishing the facade. Most often, a simple cement-sand mortar is used, a little less often - with the addition of lime or clay. A container is needed for kneading: it can be a special wide box or a trough, and if the amount of work is large, then it is better to take a concrete mixer.

Prices for concrete mixers

Additionally, you will need a shovel and a measuring bucket.

Consider a step-by-step preparation of a solution for a three-layer application of plaster.

The builders call the first layer spray or spray. The consistency of the mortar should be slightly watery in order to easily fill all the pores on the wall surface. The application thickness does not exceed 4 mm. The proportions are given for the preparation of a solution from one bag of cement (25 kg). Cement is recommended to use grades M400 and M500.

Step 1. 6 buckets of sifted sand (10 l bucket) are poured into the container, cement is poured on top.

Mix everything well with a shovel.

Step 2 Pour in 15 liters of water and begin to stir intensively, breaking up the resulting lumps. The mass should become homogeneous.

Step 3 Add another bucket of water and mix the solution as thoroughly as possible to remove even the smallest lumps. After that, you can start applying the plaster.

The primer coat is applied after the spray has set, but before it has completely hardened. The application thickness should not exceed 15 mm if the plaster is made without mesh reinforcement. The consistency of the solution is much denser and resembles a steep dough.

For kneading, take 25 kg of cement, 75 kg of sand (about 5 buckets), 17-20 liters of water. The components are mixed in the same order, but liquid soap is added with water - about 1 teaspoon per bucket of cement. Many people add PVA glue, dish detergent, antifreeze to increase the frost resistance of the coating. You can use only purchased plasticizers. These additives are not mandatory components, but they significantly improve the quality of the plaster and facilitate its application.

The third layer is called a coating, and the finest fraction of sand is used to mix the solution.

The layer thickness should not exceed 3 mm. Professional builders recommend adding lime paste to the finish layer, due to which the mixture becomes very plastic, easily rubbed, and does not shrink.

Cooking proportions:

• cement - 25 kg;
• fine-grained sand - 100 kg (about 6.5 buckets);
• lime dough - 56 l;
• water - 25 l.

In the presence of a concrete mixer, the mixing process occurs differently: first, 2/3 of the required amount of water is poured into the concrete mixer, then cement is poured in, mixed for 2-3 minutes. Then sand is poured, the remaining water is added and again interfere for 3-4 minutes. If lime is used, it is added at the same time as the cement.

Preparation of lime paste

Lime dough should be prepared at least two weeks before the start of plastering, and even better - a month. Properly slaked lime can be stored for a very long time and used as needed.

Step 1. For extinguishing, you need a deep metal container without signs of corrosion. When lime is mixed with water, a lot of heat is released, the temperature can reach 100 degrees and above, so plastic containers, especially thin ones, are completely unsuitable. So, lump lime is poured inside and poured with cold water at the rate of 1 part of water to 2 parts of lime.

Important! Quicklime is a very caustic substance, so you need to work with it in protective gloves and a respirator. Do not allow contact with skin and mucous membranes - this will cause severe irritation.

Step 2 Use a shovel or wooden stick to thoroughly mix the contents of the container to speed up the hydration process. Depending on the composition of the lime, it can take from 8 to 30 minutes to extinguish. With a decrease in vaporization, the mass is again mixed, and so on several times.

Step 3. After the reaction stops, the lime is stirred again, the container is covered with a lid and left for 2 weeks. The mass becomes plastic, all lumps dissolve without a trace and it can be added to plaster solutions.

For large volumes of work, for extinguishing, they dig a hole with a depth of at least 1 m, lime is poured into it and watered with water from a hose. When the mass stops bubbling, a thick layer of sand is poured on top and the pit is covered with boards or a wooden shield. After 15-20 days, lime dough can be used for its intended purpose.

Clay for mortar

To knead the cement-clay mortar, the clay is prepared in advance. It must be well soaked, otherwise the quality of the plaster is very low. Since dry clay is much more difficult to sift than sand, before soaking, all rubbish, blades of grass, large pebbles are simply selected from it by hand, and clay dough is filtered through a sieve before mixing the solution.

Step 1. Pour 1 part of clay into a wide trough or solution box and fill it with 3 parts of cold water. Stir with a shovel so that the clay gets wet well, and leave for at least 5 hours, and preferably for a day.

Step 2. When the clay is completely soaked, it is mixed again, kneading the remaining lumps with your hands.

Step 3. When mixing cement mortar, clay dough is added after mixing sand and cement if the work is done by hand, and together with cement if the mortar is prepared in a concrete mixer.

Factory plaster mixes

Everything is very simple here. For kneading, you need a clean container, water and a construction mixer. Read the instructions on the package, take the indicated amount of water and pour into the container. Now you need to pour the dry mixture from the bag into the water and use a mixer to bring the mass to uniformity. After that, it is necessary to leave the solution for 5-7 minutes (the exact time is written on the package). Then mix again and plaster the surface.

Prices for mixtures for leveling walls and ceilings

Mixtures for leveling walls and ceilings

Video - How to prepare a mortar for wall plaster

Cement binder based plaster is one of the strongest and most durable. However, dry ready mixes are quite expensive.

How to make a mortar for cement plaster with your own hands, what other materials will be needed, their proportions? What are the varieties and where is it better to apply them, application methods? You will find answers to these and other questions that arise during the repair in this article.

Varieties and recipe

At the moment, two types of cement binder plasters are most widely used. Their technical and operational characteristics are somewhat different from each other, which determines the optimal scope of their application and application methods.

Cement-sand mixtures

The binder is mainly Portland cement grades M150-500. As a rule, grades up to M300 are used for interior work in dry rooms, M350 and higher are used in compositions for facade work and rooms with high humidity - bathroom, kitchen, etc.

The ratio of sand and cement for plaster depends on the fraction, the required final strength or the application. For example, to apply the middle (ground) layer, sand of medium fractions of 0.5-1 mm is required with a minimum content of clay or silt deposits. Fine-grained sand is used for covering (finishing plastering).

Cement mortar for wall plastering, proportions depending on the brand

Special additives give the cement-sand mixture for plaster additional properties:

• Quartz sand and diabase flour - resistance to acids;

Quartz sand

• Barite and serpentite sands with a fraction of at least 1.25 mm - protection from x-rays;
• Metal shavings or dust added to the cement mortar gives it additional strength and increased impact strength;
• Marble flour and coarse sands 1.5-4 mm - decorative facade coatings.

Colored coarse sand for decorating facades

Various types of sand-cement plaster

1. Simple - only 2 types of work are performed, spraying and soil without the use of beacons. It is used in internal technical rooms: garages, basements, attics, where aesthetics are not important. The main purpose of sealing bare brick walls.
2. Improved - a covering is added to the previous layers, which must be rubbed with a special iron or grater. Most common when decorating residential premises or exterior walls .;
3. High quality - produced by lighthouses. At least 5 layers are applied (2-3 layers of primer). For coating, ironing with cement is used, which significantly increases the moisture resistance of the surface.

Instructions for the preparation of sand-cement mixture

1. First we sift the sand. For wet, a sieve with holes up to 4 mm is used; for dry, 2 mm;
2. 2-3 liters of water are poured into the container cleaned from the remnants of previous batches;
3. Cement is added and thoroughly mixed until there are no lumps;
4. Based on the proportions given in the tables, the required amount of sand and other fillers and modifiers is added;
5. The mixture is thoroughly mixed until a homogeneous mass is obtained, if necessary, water or a little sand is added.

The solution has the correct density if after the elongated mixer there is a hole of 2-3 cm.

Cement-lime mixtures composition and features

To reduce the weight of cement-sand plaster, slaked lime was added to its composition. If the quenching is done independently, then the minimum period of exposure to lump lime is 2 weeks. Otherwise, there is a risk of swelling and peeling of the finish. Properly prepared solution has high strength and vapor permeability.

Advantages and disadvantages

The main advantages include:

• Good adhesion to most materials: concrete, brick, foam block, wood;
• Antibacterial properties - prevents the formation of fungus and mold;
• Good plasticity of the mixture during the entire life cycle;
• High vapor permeability creates a comfortable indoor climate;
• The plastered surface is resistant to mechanical abrasion.

The disadvantages include:

• Decreased resistance to impact and stretching / compression;
• The cost is slightly higher than that of simple one-component mixtures.

Table of proportions of cement-lime plaster ingredients

Application technologies

There are several ways to apply cement-based plaster. Their choice depends on several factors:

• type of base material;
• type of plaster mortar;
• skill of the performer of works;
• availability of special equipment (machine application method)
• Finishing end goal:
  • preparatory;
  • finishing;
  • for painting.

Do-it-yourself plastering of walls with cement mortar, leveling the ceiling on the video:

Lighthouse plastering

1. The walls are carefully examined, all irregularities are noted - bumps and depressions;
2. Two extreme beacons are installed, indented from the corners by 30 cm.
3. Distances between beacons are marked. If a 2 m rule is used, then it is advisable to take 1.6 m.
4. With the help of colored twine, a horizontal line is beaten off on the surface of the base. In the places where it intersects with vertical marks, we drill holes and drive in a lubel. The distance from the floor and ceiling must be at least 15 cm.
5. The surface of the base is primed with compounds that increase adhesion. For concrete walls and smooth surfaces, special mixtures are used - concrete contact.

Plastering walls with cement mortar on beacons, video using plastic beacons:

Foundation primer

1. The extreme (corner) screws are screwed in on both sides and are set strictly vertically along the caps. Between them, twine is stretched over the surface of the hats.
2. The trimming of the beacon checks its placement under the twine, it must pass back to back. The twine is removed.
3. A mixture for fastening beacons is placed along the marking line. The lighthouse is pressed into it so that the surface is flush with the cap.
4. The verticality of the placement is checked using a rule.
5. The walls are plastered with cement mortar along the lighthouses, using the method of capping with a spatula or grouting with a trowel.
6. After filling the space between the two beacons with a layer slightly higher than the upper level, using the 2nd rule, relying on the beacons, we draw the layer from the bottom up.
7. After the plaster has dried, the beacons can be removed from the wall, and the strobes can be sealed. Mortgage plastic models can be left.
8. Grouting is carried out until the plaster is completely dry. A solution is prepared with a more liquid consistency than the main one.
9. The cement surface is pre-wetted, and then grouting at an angle of 45 °, the grout mixture is applied under pressure.

It is important if cement plaster for the bathroom is applied under the tiles, the minimum layer should be 10 mm.

Do-it-yourself plastering of walls with cement mortar, video of work without the use of beacons:

slopes

Plastering slopes with cement mortar is carried out in the following sequence:

1. Slopes are checked for verticality;
2. If the difference is large and a large amount of the mixture is to be applied To strengthen the finishing layer, a mesh is attached to the slopes;
3. The surface is cleaned and treated with a primer;
4. A restrictive rail is installed on the wall bordering the slope, the thickness of the facing layer will be oriented along it;
5. The solution is applied with a spatula to the bevel and carried out along the slope from the bottom up;
6. After the solution has dried up a little, the restrictive strips are removed and the corners are corrected.
7. The plastered surface is rubbed clean with a grater dipped in water.

Plaster door slopes video:

Finishing the slopes after installing the window, video:

Cement-sand VS plaster

In order to find out which plaster is better than gypsum or cement, we will make a comparison according to the main operational and technical characteristics:

Vapor permeability

Cement-sand plaster has a vapor permeability index of 0.09-0.1 mg / mchPa, and gypsum plaster 0.11-0.14 mg / mchPa. The difference is so negligible that it will practically not be displayed in the indoor microclimate. However, this indicator is important for the effect of moisture condensation in the room. For example, the vapor permeability of shell rock is 0.10-0.12 mg / mchPa, and foam concrete and aerated concrete is 0.14-0.17 mg / mchPa, it is recommended to use materials with similar indicators. Therefore, the use of gypsum or cement plaster for wall decoration in interior spaces also depends on the base material.

Consumption and cost

It is a big mistake to compare the cost of gypsum or cement plaster, which is better at a price per pack of 25 or 30 kg. This is fundamentally wrong, starting with the fact that perfect plasters have different specific gravity and ending with different consumption for plastering 1m 2 of the surface. For 1 cm of the thickness of the plaster layer, the consumption of gypsum mixture is 9-10 kg, and cement-sand - 12-20 kg. Considering that a dry gypsum mix costs, on average, 1.5 times more expensive, but it is used almost 2 times less, the cost of plastering 1m 2 of a wall will cost approximately the same.

Pot life of the finished solution

Cement plaster is suitable for use 2 hours, gypsum plaster with additives 1-1.5 hours without additives 30-40 minutes.

moisture resistance

The possibility of using in rooms with high humidity and in facade work has only a cement mixture.

Thermal conductivity and heat resistance

In terms of thermal conductivity, gypsum plaster is ahead, with 0.35 W / m * K versus 0.9 W / m * K. However, cement-lime and with the addition of perlite can withstand heating up to 150 ° C and open fire for a long time.

Plastering is a traditional way of leveling the walls of buildings under construction and preparing them for finishing, which is mandatory in the construction of any premises, both internal and external. In the recent past, such work was carried out in the same way using the same materials. Today we have a wide range of materials for plastering work, and finishing technologies do not stand still. To avoid errors, it is necessary to prepare a quality solution for these purposes.

Types and characteristics of plaster solutions

For plastering, a solution is made consisting of a binder component and aggregate. Clay, lime or cement can act as a binder, the choice of one of them depends on the nature of the work to be done and the place where it is carried out (inside the task or outside). Sand is traditionally added as a filler. If filler is not added to the binders, the plaster will be fragile, and the surface treated in this way will become covered with cracks. So, the following plaster solutions are distinguished:

• cement and cement-lime - used for external facade plastering of the surface of walls and basement, subjected to constant moisture; for internal work - when working in rooms with high humidity - bathrooms, kitchens, toilets;
• lime, lime-gypsum and lime-clay - used for exterior decoration of walls that are not subject to systemic moisture, as well as for internal plastering of rooms in dry rooms;
• clay, clay mortar with cement and clay with gypsum - they are considered quite suitable for interior plastering of premises with an air humidity level not exceeding the norm, and for exterior plastering of wall surfaces in areas with a dry climate.

How to define quality

When preparing a good quality plaster mortar, the raw materials should first be sieved through a construction sieve so that it is not necessary to filter the already prepared mortar, which in itself is more time consuming. A high-quality mixture, ready for use, must have a uniform consistency, the necessary fat content, be well fixed on the plastered surface, and not crack when it dries.

Distinguish plaster mortars of high fat content, normal fat content and lean.

You should be aware that greasy solutions have an increased content of the binder component, this leads to a high degree of cracking and shrinkage of the plastered surface. Normal solutions are characterized by a balanced content of all components. And lean plaster mixtures are characterized by an excessive content of aggregate, leading to insufficient strength of the plaster layer, although the surface does not crack or shrink.

To determine the fat content of the working solution for plaster, you can use an oar to mix its components. To do this, by mixing the components, we determine how the plaster mixture behaves:

• sticks too much to the mixer - we got a greasy solution, filler should be added;
• the degree of sticking is medium - we have a composition with normal fat content;
• does not stick at all - we have a lean solution that requires the additional introduction of an astringent component.

Lime mortar

1. Lime mortar, which includes lime paste and sand in a ratio of 1: 3, is brought to the required condition by adding water with thorough mixing of the entire composition. When ready, it should resemble the consistency of a thick, viscous dough.
2. In order to give the plaster mortar strength, 1/10 of this volume of cement is added to a ten-liter volume of lime plaster mixture. Thus, a cement-lime mortar is obtained. The above-mentioned lime-based compositions harden slowly, which allows you to work with them for 2-2.5 days.
3. Lime mortar with the addition of gypsum (mix 5 parts to 1 part, respectively) is more durable, and it hardens after 6 minutes, full hardening occurs after half an hour. This creates certain difficulties and requires special skills, but the plaster will be durable.
4. Lime-clay mixture for plaster is prepared from clay and lime dough taken in a 1: 1 ratio with the addition of five parts of sand. This plaster is an order of magnitude stronger, both lime and clay.

clay based

1. Clay mortar for plaster is prepared in a special way, after wetting the binder component and covering it with a dense cloth. The swollen clay (1 part) is mixed with sawdust (3 parts) and, adding water, bring it to the desired consistency by stirring. The disadvantages of the clay solution are its fragility and instability to high humidity.
2. In order to make the clay mortar stronger, cement is added to it (1/10 of this volume of cement is introduced into a ten-liter volume of clay plaster mortar). In this way, a solution is obtained with the addition of cement.
3. Clay mortar with gypsum is obtained similarly to lime-gypsum, only clay dough is taken as the main binder component.

Based on cement

Cement-based plaster mortars are mainly used for the treatment of walls that are often exposed to moisture, both indoors and outdoors.

1. The cement mortar is prepared by mixing cement with sand in a ratio of 1:3, 1:4 (depending on the purpose of use), which are diluted with water and, actively stirring, bring to the desired condition. Use the prepared mixture for no longer than one hour. Exceeding this time of work with cement mortar leads to a decrease in its quality.
2. Cement-lime mortar is prepared by mixing one part of Portland cement marked M400 or M500, ½ of lime paste and two parts of washed sand.

This type of solution is prepared in two ways:

• after mixing the lime dough with sand, cement is added to the resulting mixture, after which, stirring the composition intensively, water is poured until the required consistency is obtained;
• having made a mixture of sand and cement, thoroughly mix the solution, add milk of lime (obtained by combining 1 part of water and 1 part of lime dough).

Use of modern materials

Today, more and more often, during construction or during repair work, high-quality dry mixes for plaster are used, the basis for which is Portland cement. These mixtures, as a rule, are enriched with various polymer additives that enhance the plasticity of the solution, its adhesion to the working surface and increase the strength of the plaster. Such characteristics of the dry mix provide it with a number of advantages:

• allow you to do without reinforcing mesh and significantly reduce the consumption of plaster;
• make the plaster elastic, which ensures its soft response to weather changes - temperature or humidity changes lead to a change in its shape, and not to deformation;
• allow plastered surfaces to pass air and not collapse from moisture penetration.

Building dry mixes intended for the preparation of plaster solutions were developed by technologists in laboratory conditions, which ensured the accuracy of the proportions of the incoming components, the homogeneity of the mixture and absolute readiness for use. For the average consumer, the ability to prepare a solution, guided by a clear instruction: "Add water and work", is worth a lot.

Modified dry mixes - the achievement of innovative technologies - allow the use of new thin-layer technologies, the preparation of a solution for plastering in the right volume as needed, which, in turn, makes it convenient to use and significantly reduces costs.

In each case, each surface requires its own type of plaster mortar. When making it, it is necessary to use high quality components, because the quality of the mortar depends on this, and ultimately the quality and durability of the treated surfaces.

Video: preparation of plaster