Is it possible to add gypsum to cement mortar. All types of mortars used for the manufacture of building and decorative products from concrete, cement and gypsum. Purpose and main types of plaster

Finishing work on leveling surfaces is carried out with various materials. Depending on the location of the surface, the purpose of the room, the environment, compositions with different properties are needed.

Which plaster is better suited gypsum or cement, should be decided in each case individually. Properly selected high-quality composition will ensure a long service life and aesthetic appeal of the plaster finish. How to choose the right solution, what are the advantages and disadvantages of different compositions, we will consider below.

Types of compositions

Plastered surface ready for finishing

Plaster mortar has various applications. The most obvious are:

surface leveling;
improvement of heat and sound insulation;
fire protection.

The modern construction market offers various types of ready-made mixtures for finishing walls, ceilings, interior and exterior works. Plaster solutions are divided into 2 groups depending on the application layer:

regular or basic coverage. It is used when carrying out rough work;
decorative. Various mixtures to create a finishing finish.

The main way to classify plaster mixtures is the separation of solutions according to the constituent substance:

cement;
lime;
clay;
gypsum.

Of course, there are various modifications of the compositions, except for the 4 main ones. They are obtained by mixing the main components and adding various additives, additives and plasticizers.

Due to their practical properties, the most popular compositions are gypsum and cement plasters.

Quality criterion	Gypsum	Cement
Base material	gypsum	cement
with manual application	10	17
with mechanized	8	12,5
Drying time	up to 7 days	up to 4 weeks
Shrinkage	No	1 - 2 mm/m

Characteristics of the cement mixture

Cement mixtures have high adhesion to the base

It is difficult to overestimate the convenience and optimality of cement plaster; this type of solution enjoys well-deserved popularity among both experienced craftsmen and novice builders:

Coating strength. This is the main quality of cement plasters, the surface is resistant to mechanical stress and reliable.
Excellent adhesion. Cement mortars fit perfectly on almost any base, it is enough to treat the surface with a primer.
Moisture resistance. Cement plaster is not afraid of the effects of precipitation and high humidity, so they are often used in the repair of facades and surface finishing in specific wet rooms.
Price. This composition has a quite budget price tag compared to other compositions.

Despite the fact that this is a budget option, you should not choose a solution based only on the cost of the goods: compare the material consumption and pay attention to the performance properties.

The main disadvantage of cement mortar is poor adhesion to wooden, plastic or painted surfaces.

Due to the serious weight of plaster, it is rarely used on ceilings.

For the same reason, the load on the walls of the building during finishing should be calculated.

The plastering process itself is quite labor-intensive, despite the fact that it takes place in several stages, each of which requires a pause in work.

Engage in plastering at positive temperatures

In order for the plaster layer to be as durable as possible and serve for many years, you should follow some rules in your work:

plaster the surface at a temperature of + 5 to +30 0 С;
be sure to treat the surface with a deep penetration primer;
to apply an additional layer, you should wait for the previous one to dry;
carry out plastering work on construction beacons;
do not take on large volumes if there is no experience in this area.

Gypsum-based mixture

Gypsum plaster mixture consists of gypsum itself and plasticizers. It is applied, as a rule, in 1 layer by hand or by machine. The scope of the gypsum solution is quite extensive, although it has limitations. This type of plaster is used when finishing:

brick walls and concrete slabs;
indoor dry rooms;
for leveling the surface for gluing or painting.

Finishing the surface with gypsum mortar will eliminate the need for puttying work. High-quality work with plaster makes the surface absolutely suitable for decorative finishing.

The advantages of working with this type of composition:

The material is warm and dries quickly, it takes a maximum of 3 days to complete the work.

The disadvantages of gypsum plaster include the impossibility of using the solution in rooms with a high level of humidity.

The price tag is slightly higher than that of cement mortars, which is offset by the fact that there is no need to use putty.

Preparation of solutions

Dry ingredients are mixed first, then water is added.

It is not enough just to choose cement or gypsum plaster, for use it is necessary to properly prepare the solution. Each type of plaster has its own recommendations for the mixing process.

Bulk components of the cement composition are mixed in dry form. Sand and cement are poured in thin layers, and then mixed.

After the dry ingredients are thoroughly mixed, water is added to them. Now the liquid mixture is thoroughly kneaded.

You can also prepare cement-gypsum plaster. This solution will set much faster, drying time will be reduced. But at the same time, the strength of the layer will also change, it will become more fragile. For more information on how to make a mixture, see this video:

Gypsum mortars are kneaded within a short time. It takes no more than 5 minutes to prepare a working portion of the composition. Usually, a gypsum dough is first prepared, which is subsequently diluted with water to the desired consistency.

For leveling and finishing the walls, cement or gypsum plasters are most in demand. Both types of material have their advantages and disadvantages, which must be taken into account before starting finishing work.

In this article, we will consider the features of materials and tell you when it is better to use a gypsum-based mortar, and when you can not do without a cement-sand mixture.

What to look for when planning a finish:

basis for plastering;
indoor humidity;
air temperature;
deadlines for work;
finishing experience;
the cost of materials;
requirements for the appearance of the finished surface.

All plasters according to their purpose are divided into two groups:

Ordinary - for leveling surfaces that have defects of various nature and size, significant deviations from the plane.
Decorative - for finishing the facade or interior walls, ceilings.

Below we will consider the features of conventional leveling compounds.

Properties of gypsum and cement plaster

The characteristics of cement-sand and gypsum plasters are very different. This is primarily due to the knitting base. Application conditions will be similar - at an air temperature indoors or outdoors from +5 to +25 C. Also, the time for complete drying of the solutions is close in value (indoors at an air humidity of no more than 70%).

The table below shows how these types of plasters differ.

Comparison of advantages and disadvantages

Advantages of cement plaster:

the solution can be prepared independently;
not afraid of moisture, does not absorb water, steam from the air, does not change properties when wet;
resistant to temperature extremes;
high adhesion (reliability of adhesion to surfaces), including natural, artificial stone, concrete, brick, cinder blocks;
strength is the highest of all types of plasters, suitability for finishing places with increased operational load;
the price is the lowest among all plasters;
universality - suitability for any surfaces, including in rooms with adverse conditions.

When choosing a mixture for outdoor work, it is necessary to pay attention to frost resistance. It is usually expressed in terms of the number of freeze-thaw cycles.

Advantages of gypsum plaster:

plastic;
gains strength faster than cement, even when applied with the thickest layer - no more than 1 week;
easy to apply, just to achieve perfect evenness, no experience in finishing work is required;
has no shrinkage;
the color is white, does not show through under the wallpaper or paint;
the surface is smoother, experienced craftsmen bring the finish layer to the level of putty;
it is possible to produce three-dimensional patterns and decorative relief;
light, there is no need to strengthen the foundation and walls;
does not need reinforcement (if the layer is up to 50 mm);
vapor permeability - walls plastered with gypsum mortar "breathe";
higher sound and heat insulation properties;
less material consumption;
faster repair times;

Let's continue the comparison of finishing materials and consider their weaknesses.

Disadvantages of cement-sand plaster mortars:

poor adhesion to wood, paint, ceramics; to increase adhesion with these materials, an abrasive primer, notches or reinforcing mesh are required, but these measures do not always give the desired strength;
take a long time to gain final strength - up to 4 weeks;
the application process is relatively complex, the solution under its weight is prone to sagging; experience with such material is necessary, otherwise it will not be possible to achieve a perfectly flat surface;
the finished surface is porous, requires grouting, grinding, an additional finishing layer from another material (this does not apply to decorative plasters);
an accurate calculation of the load on the wall and foundation is necessary, since cement plaster has a high density and significantly weights the walls; it is also undesirable for finishing ceilings;
shrinkage, possibly cracking.

Most of these disadvantages can be corrected by adding modifying additives - plasticizers to the composition.

The addition of lime also improves the properties of the mortar. Read more about cement-lime plaster and its properties in our article.

The appearance of cracks is prevented by applying three layers or puttying the plastered surface. If the cement mixture is used to decorate walls and ceilings for painting or wallpapering, then puttying is required.

Disadvantages of gypsum plasters:

they are afraid of high humidity, upon contact with water they swell and fall off;
low strength;
relatively high cost;
mainly ready-made gypsum mixtures are used; experience is required for self-selection of additives to gypsum and their proportions;
it is possible to prepare the solution only in small portions due to the rapid setting, the addition of water to the solidified mixture will not restore the desired properties of the plaster, the coating will turn out to be fragile.

Where applicable

Cement plaster is used for:

internal or external works in any premises, even in unheated and damp ones, including basements, utility blocks, garages, entrances, on balconies, loggias;
finishing facades, plinths, fences, especially those subjected to aggressive mechanical stress;
filling joints when laying walls from foam or gas blocks;
processing of concrete structures, in order to increase the heat-insulating properties;
restorations subject to compatibility with the previous material;
surface finishes exposed to temperature changes;
decoration of walls or ceilings where frequent repairs are impossible.

Gypsum plaster is used for:

leveling, finishing interior walls in rooms with normal humidity;
ceiling decoration;
alignment of walls with large differences, application in several layers is permissible;
surface finishes for which cement is unsuitable - wooden, painted, ceramic;
preparation of walls and ceilings for painting or wallpapering.

Important! Gypsum mortars are not suitable for finishing the facade due to low moisture resistance. Not recommended without additional waterproofing for bathrooms, showers, kitchens.

You can protect gypsum from moisture by applying an acrylic primer. And if direct contact with water is possible, then the walls are covered with waterproofing mastic or tiled.

Combination of gypsum and cement

Can gypsum plaster or putty be applied over cement plaster? Yes, this is common practice. When finishing, the walls are often removed with a cement-based composition, and a smooth finish layer with Rotband is placed on top.

Important conditions: you need to wait until the base dries, then be sure to apply a primer between different layers.

But applying cement plaster over a plaster wall is a bad idea.. Plaster simply will not withstand its weight, and the entire finish will crumble.

It is worth noting that cement-gypsum compositions are on sale., combining the advantages of both types, for example, Prospectors MIXTER / MIXTER. According to the manufacturer, this gypsum-cement plaster is designed for interiors with normal and high humidity. This is a moisture-resistant vapor-permeable material, plastic and easy to apply.

Technical characteristics with this mixing turned out to be average between gypsum and cement plaster:

Consumption with a layer of 10 mm - 10-11 kg / m2
Water consumption - 0.36-0.42 l / kg
Setting time - 40 min
Adhesion to the base - 0.5 MPa
Layer thickness - up to 60 mm! without the use of plaster mesh
The price is 320 r per bag of 30 kg.

In addition to the main components, this mixture includes a light filler and high-quality modifying additives.

Is it possible to mix cement and gypsum plaster on my own to get a plastic, durable and moisture resistant solution? No, that won't work. Gypsum and cement have different drying times, and if they are mixed by eye and without the addition of modifiers, then the plaster layer on the wall will become cracked. It is better not to experiment with such works, so as not to waste time and money.

Let's summarize which one is better.

When choosing one or another type of finish, consider in which room the work will take place. Materials according to their characteristics must be suitable for the surface to be plastered.
Pay attention to the technical specifications indicated on the packaging.
If desired, you can increase the plasticity of the cement or moisture resistance of the gypsum plaster mixture.
Cement mortars are best chosen for the facade and wet rooms. But they require plastering skills. With large volumes of work, it is easier if experienced craftsmen do the finishing.
Gypsum plasters are easier to apply. Their main task is to finish the inside of the building.
The cost and planned timing of repairs will also affect which plaster to choose.

As you can see, the choice of plaster depends on specific goals. Choosing one type of plastering or using both is decided in each case individually.

We hope this review was helpful to you. You can leave your comments and feedback in the comments below.

Types of plaster Wall plastering with lime mortar: lime slaking, mixture proportions, application

You have decided to repair the house with your own hands, or to carry out primary finishing in a new building, and you don’t know which plaster to choose: cement or gypsum?

Before a decision is made, you should familiarize yourself with the characteristics of modern building mixtures. We will offer you a comparative overview of different types of solutions, and tell you where and how they can be used. The video in this article will help to understand this issue.

If we talk about building mixtures in general, then they are, first of all, classified according to their purpose.

These are the four main groups:

Masonry mortars for installation works
Facing (adhesive) solutions
Plaster mixtures
Decorative and special plasters (see Decorative plaster in the interior: beautiful, stylish, non-standard)

According to the component composition, they can be simple, based on a binder of one type, and complex, where there are at least two binders. Thinking about which plaster is better: gypsum or cement, many do not even realize that there are also cement-clay and cement-lime mortars, as well as mixtures based on lime and gypsum (see Types of plasters for interior decoration: choose the right one).

In large-scale construction, such plasters are most often used. They are made at on-site puttying stations, or delivered ready-made from the nearest mortar concrete unit. In the process of preparing the solution, additives are introduced into it that provide certain characteristics, and the formulations are quite complex.
It is almost impossible to make such a solution on your own, therefore dry mixes already balanced in terms of components are produced for private construction. In production, their compositions are modulated with the help of polymer additives, which makes it possible to obtain a material with desired properties. The more complex the composition, the higher the price of the material, and this is quite understandable.
Factory mixtures have an undeniable advantage: just add water, as the instructions say, and you can work. It is convenient to mix a small amount of the solution so that one person can work it out quickly. And yet, the use of ready-made mixtures allows you to avoid mistakes in the recipe of each batch, and for those who plaster walls and ceilings on their own, this is the best option.

Finishing plasters are divided into two categories: leveling mixtures and mortars with a decorative effect. Each of these categories may vary in composition, depending on the purpose: for facade (see Facade plaster for foam plastic or foam plastic) or for interior work.

There are options that, due to the presence of silicone, acrylate resins, or polyurethane, are considered universal, and can be used both outside and inside buildings. They are called polymer cement or gypsum polymer, or simply modified, and you see one of these options in the photo above.

Requirements for finishing mixes

As you can see, there are many recipes for plaster mortars, and to answer the question: “Which is better: cement or gypsum plaster?” - not as easy as it seems. Naturally, the characteristics of the solution are determined by its purpose, but there are requirements that all finishing compositions must meet.

So:

First of all, it is the appropriate mobility and high adhesion. In addition, it is necessary that the solution retains its volume when dried. That is, to avoid cracking of the screed, the plaster must be non-shrinking.
The degree of mobility of the solution may vary, depending on the fraction of the filler. For example, machine application mixes may be less mobile than hand plaster solutions.

Gypsum plasters should be the most mobile; for this, organic plasticizing additives are added to them. Gypsum-based solutions set very quickly, so the timing of their hardening also needs to be regulated. As in the case of mobility, this is achieved by introducing special additives into the composition.
Decorative plasters are distinguished by the highest plasticity, because such a composition must not only be applied and leveled, but also have time to mechanically process the covering layer before hardening.
In their production, white and colored Portland cements are used, if these are compositions for exterior decoration, and gypsum, if the plaster is intended for interior work. Lime can be introduced into both mixtures - for example, if they are intended for plastering walls made of silicate concrete.

In finishing plasters from organic fillers, only sand is used. As for decorative solutions, depending on the effect, they may contain crushed glass or mica, marble or granite chips, crushed limestone, dolomite, as well as artificial and natural pigments.

Application of plasters

Cement-based mortars are the most durable, and when dried, they form a stone that is practically not susceptible to moisture. That is why they are used for plastering facade walls, as well as rooms with a high level of humidity. Purely cement mortars are not very plastic, therefore lime or polymer additives are introduced into them.

Lime-cement and lime-gypsum mortars are good for plastering wooden surfaces. Polymer cement compositions are ideal for systematically wetted structures. So, if you need to make protective plastering of the basement walls - this is the best option.
Inside the house, such compounds are used only for leveling walls in bathrooms. In other rooms, they are recommended to be used only for making a leveling screed for facing with ceramic tiles or natural stone. This is important, because the strength of the base must always be higher than the strength of the coating.

In other cases, gypsum-based solutions are used for interior decoration of residential buildings and apartments, and readers' interest in them is the highest. For this reason, we will pay more attention to the question in which situation and which gypsum plaster to choose in order to make the leveling at the lowest cost.

Varieties of gypsum compositions

So, you went to the hardware store to purchase the necessary material. You have a considerable assortment in front of you: gypsum plaster - which is better? Let's look into this issue together.

The main criterion for selecting a variant of the plaster mixture is the quality of the base. Therefore, before you go to buy building mixtures, the condition of the surface to be plastered must be assessed.

To do this, you first need to clean it, if it is a repair, or immediately carry out hanging, if it is a primary finish. This will make it possible to calculate how thick the screed should be, and accordingly, decide which gypsum plaster is better.

This does not mean products under a certain brand, but the physical and mechanical properties of the mixture, which are declared by this manufacturer. So, the best gypsum plaster is the one that meets a specific task, in which there are two main conditions: the type of surface, and the size of its deviations from the plane.

Plasters for different types of surfaces

When it comes to apartments, most often the walls in them are either built from large panels, which are made from heavy concrete, or it is masonry from silicate - less often, red brick.

So:

In private houses and cottage construction, blocks of lightweight and cellular concrete are often used. They are also used in the construction of multi-storey frame-type buildings. In them, the frame bears the main load, and light blocks of a small format are very convenient for the construction of enclosing structures.
Of course, the design features of buildings do not play any role for the choice of plaster. But it matters what kind of filler is used in the production of concrete blocks from which the walls are built.

For polystyrene concrete, gas silicate blocks and foam blocks, special plasters are provided (see How to plaster foam blocks according to technology), which provide increased adhesion and vapor permeability of the screed. In principle, for plastering such surfaces, adhesive compositions used for masonry work can be used.
They are called so: adhesive plasters, and they are always made on the basis of cement. Gypsum-based compositions are used only for plastering, since they are not suitable for masonry and installation work. Due to the large number of pores, which can be both closed and open, cellular concretes intensively pass moisture and air.
In the compositions for their plastering, perlite is often present - an organic filler, which, due to its low thermal conductivity, belongs to the category of heat-insulating materials. Perlite granules partially close the pores on the concrete surface, while allowing the walls to “breathe”.

In general, for plastering such surfaces, lime-cement and lime-gypsum plasters are simply ideal. The technology for the production of plaster work on a concrete base with a cellular structure also has its own characteristics, but this is a completely different topic.

For interior decoration of walls made of brick and heavy concrete, any gypsum plaster compositions are suitable, and not only gypsum ones.

Interior work: why gypsum mixture is better

Preference is given to compositions based on gypsum, due to the white color. For interior work, water-dispersion paints are mainly used, but they do not have such high hiding power as, for example, oil paints or alkyd enamels.

This means that in order to paint over a dark cement screed, you will have to apply more layers, which leads to an overrun of the material.

Even when wallpapering, cement plaster can shine through a thin light-colored canvas, and spoil the whole aesthetics of the finish. For this reason, when leveling indoor walls, cement-based compounds are used only for tiling.

And one more important nuance. Many readers are interested in: "How long does gypsum plaster dry?". Of course, this depends on the thickness of the layer and the temperature in the room. But in any case, the gypsum screed will dry twice as fast as the cement screed. In the first case, a layer of 1 mm hardens in 4-5 hours, in the second case, it will take 8-10 hours.

The answer to the question: "Gypsum plaster: how long does it dry?" - quite simple. In practice, each coat usually takes at least 12 hours to dry. That is, during the day a layer of plaster is applied, for example, 2 mm thick - it dries out overnight, and in the morning you can safely continue work.

If the irregularities of the base base are such that it is necessary to plaster with a thick layer of 15-20 mm, then it may take at least 3-4 days to dry.

Selection of plaster according to the quality of the base

Gypsum plaster: which is better? Which option to prefer if the walls are relatively even, and which one if it is crooked brickwork? In this part of the article, we will discuss the principle of selecting a mixture according to the quality of the base.

If the walls or ceiling do not have significant deviations from a single plane, it is enough to putty small cracks and surface shells, and then apply a thin layer of one layer of plaster.

According to this principle, walls are plastered in panel houses, cosmetic repairs are made to old, but still strong plaster, and surfaces are prepared for painting, leveled in a “dry” way - using drywall.
For such walls, gypsum-polymer compositions are usually used that do not require puttying. Due to their high plasticity, they have excellent adhesion, and are suitable for plastering almost all surfaces, even foam concrete walls. In any case, you need to read the manufacturer's instructions, where the purpose of a particular composition, as well as the thickness of the applied layers, are clearly regulated.

Everything related to masonry: even brick, even block, does not look so optimistic. Walls built from blocks are even more or less even. But brickwork rarely boasts of high quality, because, as a rule, everything goes into work: bricks with potholes, chipped corners, cracks.
Therefore, even if there are no bumps and large recesses in the masonry, there are still many other shortcomings that have to be eliminated during the plastering process. To align such walls, you have to use compositions with different fractions of the filler.

Starting, or, as they are also called, base plasters (putties), have a coarser dispersion, and are applied with the first layer on the wall treated with a primer. This layer has the greatest thickness, and is designed to hide the largest defects in the base.
If the depth of the recesses exceeds 2 cm, and this happens quite often, the alignment can be done in two layers, between which a reinforcing fiberglass mesh is mounted.
Since the components of the base putties have a rather large dispersion, the surface of the screed is grainy, and a finishing composition is used to smooth it out. Its ingredients are finely ground, so the dry mix is more like a powder.
The finishing plaster solution is extremely elastic, and when applied to the starting screed, it fills the smallest pores and cracks in it. Thus, the surface is brought to perfect smoothness.

Finally, we recall that it is better to purchase mixtures of "start" and "finish" from one manufacturer. In this case, you can be sure that their compositions are maximally adapted to each other, and they will not create any problems in the work.

Good plaster lasts for decades. Now gypsum mixtures have replaced cement finishing coatings. But not all plasterers refuse the usual materials. Let's look at the strengths and weaknesses of gypsum and cement mixtures and figure out which plaster is better.

Features of cement-based plaster mixture

The word "plaster" comes from the Italian term stuccatura, which denoted the finishing materials familiar to the Romans (lime, alabaster, gypsum). Modern plaster is a hardened building mixture intended for leveling walls. It is unambiguous to say which solution is better and which is worse. The composition of the optimal coating depends on many factors.

Plaster solutions have been used for thousands of years to decorate houses, apartments, building facades. The demanded finishing material has evolved along with humanity. In recent decades, when building and repairing houses, builders have mainly used cement coatings.

The mixture consists of cement (main component), sand (filler), plasticizers. As the latter, limestone, gypsum, or combinations thereof are used. Solutions are distinguished by the proportions of the components and depending on the surfaces to be finished. Cement-based coatings cover the walls outside, inside buildings. Moreover, in the latter case, the premises may be unheated and with high humidity.

The strengths of cement finishing mortars include:

universality;
plasticity lasts for several hours - you can immediately prepare a large volume, spending it as needed;
strength of the finishing layer;
affordable price.

However, cement plaster is far from ideal. Masters note the following shortcomings:

the mixture does not fit well on the concrete base:
the layer dries for about 14 days, which reduces the pace of finishing work;
high humidity when working with the mixture - for the crystallization of cement particles, the surface to be trimmed must be sprayed with water;
the main component cement gives the finished surface an unsightly gray color;
at the final stage, finishing puttying is mandatory;
when working, a suspension of sand, cement, which enters the respiratory tract, rises into the air.

The main problem when working with cement coatings is a cracked finishing layer. In addition, as it dries, the composition will shrink, which will lead to irregularities. By the way, for this reason, additional equipment (heating elements, hair dryers, heat guns) is not used for drying rooms.

Thus, the cement finishing mortar is suitable for walls in technical rooms, facade work, in apartments with draft and.

Advantages and disadvantages of gypsum coatings

Despite all the advantages of cement mortar, gypsum plaster confidently competes with it in interior decoration. As the name suggests, the main component of the mixture is gypsum powder, made from a natural mineral. During the production process, after a long heat treatment, this powder is crushed. As a result, the finer the fraction (grain size), the better the treated surface.

In addition to gypsum, the composition of the solution includes natural or synthetic fillers, polymer additives. For leveling walls, the shape and size of the grains are of no small importance. In addition, fillers reduce the cost of the mixture and increase the strength of the finishing layer. And the polymer ingredients increase the adhesion of the solution, make it more elastic.

Based on the technical characteristics of the finishing coating, its advantages can be distinguished:

High adhesion - the solution falls on any base;
Leveling ability - the surface finished with gypsum coating is immediately ready for painting, whitewashing, wallpapering;
The consumption of this mixture is lower than that of cement. True, for this you need to follow the rules and technology of work;
Solid thickness of the finishing layer - sometimes it reaches 6 cm;
It is easy to work with the mixture - it fits well on the surface, leveled, smoothed;
The surface treated with such plaster acquires additional sound and heat insulation qualities.

Despite all its positive qualities, gypsum coating is not used everywhere. There are reasons for this:

Price. Gypsum mixture costs 1.5–2 times more than cement;
Strength. The surface plastered with gypsum coating does not withstand mechanical damage;
The solution quickly seizes, therefore, in order to avoid overspending, it will have to be prepared in small batches;
The need for additional materials. For example, when treating a concrete surface, it is necessary to use primers, and plastering metal surfaces without a waterproofing layer is unacceptable. In addition, it is not recommended to lay tiles on this decorative coating. Upon contact of the adhesive composition with the finishing material, ettringite is formed - a mineral that destroys gypsum.

The main disadvantage of such a mixture is the undesirability of using it for surface treatment outside the house.

There are three types of gypsum finishing coatings. The first is a fine-grained solution, it includes carefully ground sand. Such material is recommended to be applied in layers of 0.5–0.8 cm thick. For leveling, apply a second layer. The main area of application is the decoration of ceilings.

Medium-grained gypsum mortar is the most popular and, as a result, widespread. It is the main competitor of cement-based mortars. Allowable thickness 5 cm.

Coarse-grained gypsum plaster is used to hide significant surface defects. As a rule, broken slopes are repaired with its help, facades are updated. By the way, in the latter case, the selected mixture must be checked for resistance to water. Sometimes, despite the claims of manufacturers, it is better to play it safe and apply a protective layer.

Work with gypsum and cement plaster - a comparative analysis

The main factor determining which plaster is better and which is worse is the characteristics declared by the manufacturer. But along with them, secondary factors must be taken into account - ease of use, the need to use additional materials.

At first glance, the advantages of gypsum coatings are obvious - they are elastic, stick to any surface, and are easy to set. And the faster the layer hardens, the faster the work moves. But with insufficient skill, the prepared batch of plaster will dry out. It cannot be reused. In other words, the price of a mistake is an additional cost, and the cost of gypsum plaster is not affordable.

Cement plaster mortar dries for at least two hours, which allows covering large areas in one go. However, the adhesion of such a composition is lower and in some cases (ceiling, corners) the surface will have to be reinforced with a plaster mesh. On the one hand, this entails additional labor costs, on the other hand, the strength of such plaster is many times higher.

As you can see, the answer to the question of which plaster to choose will be ambiguous. For outdoor work, cement plaster will be the best option. But gypsum mortar is a great option for working inside the apartment (with the exception of the kitchen, bathroom,). In rooms with high humidity, you will have to cover the finished surface with varnish.

Self-preparation of plaster mortar is a good way to save on building materials. After all, the ingredients for the solution are sold on any construction market. And buying them separately is cheaper than bringing a complex product to the construction site. If a small surface is to be repaired and the packaging of the mixture for solid plaster obviously cannot be used, it is easier to prepare a solution for plastering walls with your own hands. The main thing is to know in what proportions to mix.

If you are making your own plaster mixture for finishing the entire room or for plastering the house outside, it may be worth buying or renting a concrete mixer or a construction mixer to reduce labor costs.

Compositions for various surfaces

Plaster mortars consist of binders, aggregates and modifying additives. Additives are used to enhance the plasticity and strength of the solution, to give it hydro- and noise-insulating properties, or to create decorative effects.

There are special varieties of X-ray protective and acid-resistant mixtures - but the latter are prepared only in production, with strict technology control.

The filler in most solutions is sand. The binding of the components of the mixture when water is added is provided by cement, gypsum, clay, lime, or combinations of several of these minerals.

In a wall plaster mortar, the proportions of the ingredients and theirs are determined by the intended use of the plaster. So, for plastering buildings from the side of the street, a solution is usually taken, including a higher percentage of a binder.

It is also useful to know which plaster is better. For finishing the facade of buildings / buildings, it is also used. When plastering fireplaces, you need to use components that can withstand high temperatures.

Plaster mortars are classified based on the name of one of the binders that make up the mixture. On this basis, there are:

cement-based mortars;
lime-based solutions;
clay-based solutions;
mortars based on gypsum or with a high content of gypsum.

In practice, of the solutions with one binder, only cement is widely used. The remaining popular mixtures are more complex - cement and lime, lime and clay, lime and gypsum are used simultaneously.

Fillers that create relief are added to decorative plaster: granite, tuff, marble, dolomite, crushed glass.

For decorative purposes, various dyes are also used, which create a uniform and durable color of the plaster layer: thanks to dyes, the plaster does not require further finishing.

Cement mortar: an almost universal mixture of cement

This type of solution is suitable for most types of surfaces, and outside it will best protect the concrete building structure from moisture and cold.

The advantages of cement mortar are the extreme strength of the finished plaster, the relatively low price of ingredients, ease of preparation, slow setting (which allows the mortar to be prepared in advance for trouble-free operation).

The main disadvantage is the ability of cement plaster to shrink, crack during the drying process.

For more information about the preparation of cement mortar, see the video:

The proportions of cement and sand in the mortar for plaster can be different: 2-5 parts of sand are taken for one part of cement. Higher grade cement binds plaster better and requires less. But the dependence of the brand and the amount of cement in the mixture is non-linear.

Adding sand to a certain limit increases the strength of the plaster, but reduces its plasticity and ability to adhere to the surface.

There is a belief that the first number in the name of the brand of cement (from 200 to 500) means the number of parts of sand that the cement can bind. The numbers indicate the "binding force" only indirectly, but only indicate the strength of hypothetical products made of pure cement.

Namely: cement stone, which will be made of M500 cement (option - PC500), will be able to withstand a load of 500 kg per 1 cm3. Therefore, mixing a kilogram of M500 with five kilograms of sand is a bad idea: the solution will not stick to the wall and will quickly collapse.

The normal proportions of cement mortar for wall plastering are 2-3 kg of cement per kilogram of sand. Two - for cement M 300. Three - a suitable ratio for M 400 - M 500, (plaster from cement M 500 will be stronger).

As a rule, for the first layer of plaster, a leaner solution with a lower cement content is taken, and for the finishing one, a greasy one.

In almost any room, it is required to provide warmth that will not freeze and warm even in the coldest season. By clicking on, learn how to make a screed for a warm water floor.

For the correct installation of the screed, it is necessary to know the nuances of the source materials, the proportions of their mixing, and also take into account the type of surface and its condition. find out what proportions the floor screed mortar should have.

Installation of a warm floor in a house or apartment is invariably accompanied by work on the formation of a screed. Here is all the useful information about optimal underfloor heating.

To prepare the solution, sand of medium or fine (but not the smallest) fraction, purified from impurities, is used. Even stronger plaster will turn out if you use two fractions at once in approximately equal volumes: medium, which passes through a sieve with cells of 2-2.5 mm, and fine (1.5-2 mm).

A solution using coarse sand will not allow you to finally level the surface, but the use of too fine (less than 1.5 mm) sand threatens to crack the finished plaster.

How is cement-sand mortar prepared?

To prepare a cement-sand mortar, pour the required amount of sand into the mixture container.
After that, pour cement on top. Next, you need to mix sand and cement to get a mixture of even gray color.

Then you should gradually pour in water, constantly stirring the solution. Stop mixing when get a mass of sour cream density, which can be held on a vertical wall.

The easiest lime mortar for wall plastering consists only of lime and sand in a ratio of 1:3 diluted to a convenient consistency with water. Sand, as for other solutions, needs clean, free from impurities, with particle sizes not exceeding 5 mm.

Suitable, like quicklime, but quicklime will still have to be paid off first, i.e. dilute with water and wait until the “boiling” stops.

The main advantages of lime plaster are low price, good adhesion to the wall material, high plasticity. However, plasters, where only lime is used as a binder, are used exclusively indoors: it is fragile and collapses in the rain.

Instability to moisture also determines the impossibility of using lime plaster in bathrooms, damp basements, and laundries. Another disadvantage of lime plaster is the setting speed: it cannot be prepared in large portions.

Most of the shortcomings of lime mortar can be smoothed out by adding cement to it.

A more durable cement-lime mortar for plaster, the proportions of which are from 0.5 to 1.5 measures of lime per measure of cement and 2-4 measures of sand.

Such plaster can be applied both to external and internal walls, including in bathrooms and laundries. The setting speed of the mortar can also be reduced by adding cement: it becomes more convenient to work.

The exact ratio of components in the mixture is chosen differently for different layers of plaster (less lime is needed for the first layer, more for the finish).

How to make lime mortar for plaster walls: proportions and technology

To prepare a lime and cement-lime mortar for plaster, dry lime should be measured immediately in the right proportion and diluted with water - the so-called milk of lime will be obtained.

The quicklime will “boil” at the same time: you need to wait for the steam release process to complete before taking the next step. A solution of slaked lime is used immediately.

The remaining dry ingredients are added to lime milk: only sand or sand mixed with cement.

All this mass is stirred and, if necessary, diluted to the desired density. It is necessary to work out the whole batch in 1-2 hours.

Clay mortars are prepared in the same way as lime mortars: first, clay dough is diluted, then aggregate is added and the mass is leveled in density.

How to use clay for wall plastering

However, a purely clay mortar for plastering walls is not used, the proportions of 1 share of clay in the composition of clay dough for 3 mass fractions of sand are remembered only when it is necessary to make a clay “shell” for a chimney. Clay-cement and clay-lime mortars are used for plastering walls and furnaces.

Clay-based plaster mixes are preferred if you need to plaster a wooden surface. The ratio of clay and cement in such a solution is 1: 0.2, clay and lime paste - 1: 0.5.

If the clay solution is prepared for finishing the furnace, then asbestos or crushed fiberglass is additionally placed in it: 0.1 parts per 1 part of clay.

This enhances the strength of the finish. As usual, you also need a filler - sand: 2-3 measures per measure of clay.

Do-it-yourself gypsum mortar

Gypsum-based mixtures on the construction site are not very common., since it is inconvenient to work with them: the gypsum mortar sets too quickly, 4-6 minutes after kneading.

Gypsum mortar is appropriate if you need to repair a deep crack in an interior wall: gypsum plaster does not shrink, so your patch will not crack. It is also desirable to know him. Such a "repair" solution is made without aggregate: it is enough to mix gypsum and water for it.

To repair wooden surfaces, arbogypsum is used: gypsum and sawdust are mixed in equal proportions, then diluted with water to the density of sour cream.

Features of a gypsum-based mixture, is sand added

Most often, gypsum can be found among the components of a lime-gypsum mortar. In this building mixture, one part of gypsum is combined with three parts of lime. The ingredients are used in a liquid state, no sand is added. A water-gypsum solution is prepared right before work, and lime dough is made in advance.

This solution also sets quickly, but still a little slower than pure gypsum. And besides, the plaster is stronger than from each of these materials separately.

The property of gypsum to accelerate the setting of building pastes can be useful if the speed of repair is fundamentally important.

A small amount of gypsum can be added to any plaster mixture so that after an hour you can continue finishing work on top of the applied layer.

Special cases: plastering of external walls and plinths

The proportions of the mortar for plaster do not differ from those used in plasters for finishing walls inside the room. However, not all types of plaster are suitable for outdoor wall application.

Lime and lime-gypsum mortars are not used, most often cement and lime-cement mortars are taken. Sometimes the best choices are plasters with the addition of clay or with gypsum in the mixture, but they definitely need an external protective layer.

In plaster mortars for outdoor use, additional "additives" are often added to give strength to the plaster layer. The most famous additive is PVA glue.

The choice of the main binder in the plaster solution is determined by the material from which the house is built.

for concrete walls, as well as for walls made of cinder blocks, standard cement-sand plaster is suitable, ideally with the addition of PVA;
for brick walls, lime-cement plaster is preferable, which helps prevent wall moisture;
rubble stone walls are best coated with a mixture of sawdust and clay, and then painted;
foam concrete walls are usually sealed with ready-made mixtures - gypsum-perlite or silicate. Gypsum-perlite then need additional protection;
wooden houses are covered only with clay-based mortar, sometimes mixed with sawdust.

Finishing the basement is difficult due to the fact that this part of the building is constantly exposed to moisture.

Plaster mortars for the base are usually made on the basis of ready-made mixtures with hydraulic additives.

To prepare a mortar for plastering a basement, you can also use a mixture of ordinary cement with sand in proportions of 1: 3 (spray and primer layer) and 1: 1.5 (finish, finishing layer).

A hydraulic additive can be purchased additionally and combined with the prepared solution.

What to consider in order not to be disappointed in the self-preparation of the solution?

The conditions under which the solution will be applied. Both the composition and the ratio of ingredients depend on this. In most cases, plaster is applied in several layers, the proportions of binder and aggregate are selected separately for each.
The material of the walls that is covered with plaster. Different materials adhere well to different solutions.
Ingredient Characteristics, their availability and the ability to purchase technologically necessary additives.
Affordable labor productivity and plaster setting speed. Do not prepare a volume of solution that you will not have time to use. But kneading a new portion every half hour is also not very convenient.

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