Do-it-yourself mortar for plastering walls: what mixture to use and in what proportions? Choice of plaster: gypsum or cement Silicone plaster mixes.

I can unequivocally answer this question, it is impossible to add gypsum to the cement mortar, even in small quantities. Although they say that in the production of cement into clinker, this is an intermediate product, a small amount of gypsum is added one or two percent, but I'm not strong in chemistry, I don't know. But I have extensive experience in plastering with cement-sand mortar with the addition of gypsum.

I even had to work for such unscrupulous foremen who, apart from this “ominous mixture”, did not work with anything else. Why is this needed? The speed of work increases five to ten times, and as you know, the faster you hand over the object, the faster you get the money. And do not think that only small private traders are guilty of this.

The plaster layer made with a cement-gypsum mixture after a while, one to five days, depending on the base, begins to become covered with a web of very small cracks, they can be seen if the surface is well primed with a primer. You can putty and forget only if the base is made of red brick, and plastering work were carried out indoors. But in most cases, gypsum is added to cement when plastering. concrete bases, on red brick, plaster sets quite quickly even without gypsum.

The favorite excuse of such plasterers, if the cement-gypsum plaster layer is rubbed from above with a solution without gypsum or puttyed with facade putty, then everything will be in order. This is a pure lie, checked more than once, does not help.

Each layer of cement-sand plaster, on concrete wall, it will set from 5 to 10 hours, and there may be several such layers. The addition of gypsum allows the job to be completed in one pass, the plaster will become hard (but not dry) in 5 to 10 minutes. Such plaster will not last long, indoors up to 5 years, on the street it will not survive the first winter. If a metal mesh was stuffed under such plaster, it will begin to rust very quickly in 3-6 months. outdoors and for several years indoors (depending on humidity), and traces of rust will constantly appear on the surface.

Before 50 - 80 years, there was a practice, when plastering the ceiling, upper slope, etc., add gypsum to the cement-sand mortar, at that time it was the only solution, even in the educational literature of that time you can find a recipe for this plaster mortar. Currently, to increase the plasticity of the mortar, plasticizers and a number of other additives are used to improve the adhesion of the mortar, and gypsum is added to the composition of the cement-sand plaster mixture only in order to save money.

Plastering the ceiling or the upper slope with cement-sand plaster is very difficult (long), in such situations I add tile adhesive (1 to 5 or 8) to the cement-sand mortar. This facilitates the work of the plasterer and saves on plaster mixtures, but at the same time does not lower the quality of work.

The modern market offers a huge variety of building materials. This, in turn, led to a significant expansion of the list of options for finishing the ceiling, walls, floor and other structural elements premises. But in this article we will not consider in detail the various technologies and their place in modern construction. The purpose of this material is to provide answers to the questions that many homeowners have regarding the use of dry gypsum material for finishing one or another element of the room.

So, before starting work on puttying the walls and / or ceiling, you should know that there are two main types of gypsum mixture - starting and finishing. Under the starting putty, they mean gypsum (with various kinds of plasticizers) with a rather large fraction size, which is used for a “rough” finish. As for the finishing material, this gypsum has a smaller fraction size and is used for the final surface finish (you can read about the characteristics of this material in the article "").

We also note that very often gypsum is used as a material for plastering. inner surface wall, for example, made of bricks. Of course, many do not recognize the use of gypsum as a plaster, believing that there is nothing better than cement in this case. By by and large, these are unsupported opinions and statements - as practice shows, plaster made of gypsum is in no way inferior to plaster made using cement mortar.

Well, actually, that's all - the introductory part is over, we can start answering the questions that are most often asked by professional builders about gypsum as a material and about the features of working with gypsum putty.

Starting and finishing putty - the main features of the materials

To begin with, we will deal with issues related to the preparation of a solution based on a dry gypsum mixture. So:

How to prepare putty for walls and ceilings?

In principle, there are no special nuances here: take a little dry mixture, add water to it and stir thoroughly. The only thing to remember is that gypsum should be added to water, and not vice versa. Remember that if you add water to a container with a dry mix, then you won’t get a normal solution - the gypsum will simply be taken in a lump, and no stirring will help. You can also advise: after the putty mixture is ready to work, let it stand for a while to better dissolve the gypsum fractions (approximate exposure time is 3-4 minutes). For more clarity, I recommend that you watch a video that reflects the process proper cooking putty mixture. We look:

Can expired putty be used?

Of course, it is not recommended to use anything overdue - everyone knows this. However, if we talk about expired putty, then in principle, in some cases it can be used for finishing works. True, this applies only to the starting mixture, finishing gypsum, the expiration date of which has expired, should not be used, because, as a rule, due to old age, its fractions, when diluted with water, turn into lumps, which cannot be stirred.

Can gypsum and cement be mixed?

Such an operation is strictly prohibited. It must be understood that cement and gypsum are materials that are completely different in structure, which “conflict” with each other in the dissolved state. In other words, cement simply “extinguishes” the properties of gypsum, almost completely destroying its useful characteristics.

Can gypsum and sand be mixed?

Someone will additionally ask this question - why add sand to gypsum? Answer: such a rationalization move is quite often resorted to when the area on which it is necessary to apply the putty is quite significant, but there is a budget constraint on the material. Simply put, the addition of sand allows you to save quite a lot when plastering or starting puttying the walls. Can sand be added to gypsum? Answer: yes, you can - the surface treated with such a solution is quite reliable and durable.

Features of working with gypsum solutions

Having considered some issues of using a dry mix, you can move on to issues that are directly related to the use of ready-made solutions. Let's get started:

Do drywall need to be primed before plastering?

Let's just say: not necessary, but highly desirable. It must be remembered that the primer significantly increases the adhesion of the putty to the surface on which it is applied. That is, before work begins with gypsum putty, it is desirable to prime the surface to be treated, regardless of what it is, whether it is cement plaster, drywall, foam plastic or anything else.

Can putty be used instead of grout when laying tiles?

Theoretically, this is possible, but, again, tile grout is specifically designed for this purpose. It has higher moisture-resistant and strength characteristics compared to putty. In practice, tile joints sealed with putty are short-lived and impractical.

Is it possible to putty on whitewash?

It so happened that in the old days one of the most popular finishing materials was lime, with which the ceiling and walls were whitewashed, thus obtaining a quite decent appearance at a fairly low cost. But times are changing, and today lime is rarely used for finishing. Is it possible to putty on whitewash? If you want really good results, then no. The fact is that when applying putty, the solution adheres precisely to a thin film of whitewash, but not to the ceiling or wall itself. As a result, after drying, the gypsum coating becomes fragile (as a rule, it can be very easily “scraped off” with the most ordinary spatula).

In the construction of dwellings, gypsum mixtures have been used for many centuries. Ancient civilizations have left us many architectural monuments in which building materials based on gypsum binders were widely used.

The use of compositions based on cement and gypsum is due to the mass of positive qualities that are characteristic of this particular group of binders. They practically do not precipitate during hardening, quickly gain strength when solidified, gypsum materials have impeccable sound-proofing and heat-resistant qualities, good fire resistance, and, most importantly, this is an environmentally friendly composition.

Low cost plaster

Especially important is the use of mixtures based on gypsum and concrete for Russia in the construction and decoration of buildings and structures because: the lion's share of all the planet's reserves of natural gypsum is concentrated on Russian territory; the price of manufacturing a gypsum binder is very low (5 times) compared to the price of cement manufacturing; energy costs in the manufacture of 1 ton of gypsum are 3-6 times lower than in the production of a ton of cement.

Why Should You Use Supplements?

Despite the age-old experience of application and the abundance of positive qualities possessed by dry mixes of concrete or gypsum, these finishing materials are used in Russia only for plasters and putties on premises. The reason for this was low water resistance and low strength characteristics, since gypsum dissolves quite well in water, and when hardened, it has high porosity. But, the solution to these problems was found. To eliminate such shortcomings, additives are used that, when interacting with gypsum, form compounds with lower solubility.

Modifiers

One of the ways to solve problems with the strength and water resistance of concrete and mortars based on gypsum concrete binders is the admixture of a special kind of impurities - modifiers.

Modifiers are a carefully selected combination of organic and mineral components, which are first subjected to special processing and optimized in composition. With the help of these dry modifiers, formations become more water resistant, a denser structure is formed. Thanks to such modifiers, the mixtures not only increased their compliance sanitary requirements, but also significantly improved moisture resistance, increased the speed of curing materials.

Quality improvement

The combination of these properties provides the following benefits:

• the energy saving of buildings is increased due to a wide range of strength characteristics, water resistance and frost resistance;
• use materials based on modified gypsum not only as finishing materials in residential premises, in buildings for various purposes and number of storeys, in enclosing, load-bearing structures;
• no need to use heavy construction equipment;
• construction time is reduced several times, and the initial cost of construction is significantly reduced.

Application

To date, dry modified mixtures based on gypsum and cement are the most popular in comparison with a number of other finishing materials. Dry modified mixtures are used in leveling walls, ceilings, flooring, in tiling, masonry work, and are also used not only for puttying and plastering, but also as tile adhesive, self-leveling floors, etc.

Thus, if we take into account the many shortcomings in the cement industry, and these are inflated prices for Portland cement, and the shortage of its supplies, then the use of mixtures based on gypsum and concrete with the addition of modifiers is the best choice in the range of finishing materials.

Question: which plaster is better - gypsum or cement is relevant when carrying out capital and repair construction works. These binders are a popular basis for ready-made mixtures for leveling, cladding and preparation before finishing decorative surfaces. Each material has its advantages and disadvantages, choosing the right option is not easy. The main guidelines are: price, operating conditions, ease of installation and timing of its implementation.

Being universal, cement-sand plaster is well suited for both exterior and internal works. It is not afraid of dampness and temperature changes and is often used for leveling walls, slopes and other surfaces (up to unheated and basements), finishing in conditions of high humidity, processing concrete structures in order to increase thermal insulation properties. This perfect option masonry mortar in the construction of buildings from aerated concrete or foam block. Distinctive features cement mixture is high adhesion, durability and strength, it should be chosen when conducting capital construction or for restoration on an old surface (subject to compatibility of materials). This point is important: cement does not adhere well to plastic, wood or painted surfaces.

Significant application limitations include a complex application process and a long drying time. The work is carried out in several stages: spraying, throwing, rubbing and grinding. Get perfect flat surface through the use of cement plaster is difficult, not everyone has the necessary skills, while with gypsum such problems do not arise. It dries for a long time - up to 3 weeks, even if a thin layer is applied. The resulting surface is porous and not well suited for subsequent decorative finishes(dark, needs filling and polishing). In general, cement mixtures are not decorative, with the exception of species with special additives.

Gypsum-based plasters are more plastic and do not shrink, as a result - this is an ideal option for leveling internal walls. They dry much faster, additional puttying is not necessary, their structure is already quite smooth without it. The main color of gypsum plaster is white, it does not show through under wallpaper or paint. At the same time, it easily comes into contact with coloring pigments, it can be chosen as an independent decorative finish, in addition, it takes the desired shape, including three-dimensional patterns. Light weight allows applying gypsum mixtures without the risk of overloading structures, and only poor water resistance prevents them from being called universal. Under the influence of moisture, gypsum is destroyed, so this plaster is not used for outdoor work.

Comparative overview of benefits

The advantages of cement-based mortars include:

• Strength and durability. They are best suited for restoration and finishing outdoor work and withstand mechanical and other external influences well.
• High quality adhesion to aerated concrete, smooth surfaces natural or artificial stone previously plastered walls. This is an ideal plaster for foam blocks (both masonry and finishing), its consumption on porous material is minimal.
• Low cost, cement types of plaster are 1.5–2 times cheaper than gypsum ones. This applies to both ready-made building mixtures, and mixed independently.
• Moisture resistance is the main advantage of cement mortars. It is this property that allows them to be used as plaster for slopes, facing bathrooms, bathrooms and kitchens. Gypsum under the same conditions is permissible only with subsequent protection of the surface with tiles. Also, this ability allows the use of cement compositions for outdoor work.

The advantages of gypsum plaster are:

• Quick and easy installation. They dry twice as fast as cement, with the same layer thickness, and are easy to process.
• No shrinkage processes. When hardening, the risk of cracking is minimal, in comparison with cement plasters.
• Plasticity: solution without special efforts takes a certain shape or is distributed over the wall with the desired layer thickness.
• Environmental friendliness and vapor permeability. This is a "breathing" plaster, safe for humans and favorable for the indoor microclimate.
• Sound and heat insulation abilities. porous and light structure better than others retains heat and prevents the penetration and spread of noise.

Due to the listed properties, gypsum mixtures do not need reinforcement (with the exception of layers from 50 mm), do not drain from vertical walls and keep a given shape well. Their use significantly reduces the repair time, construction skills are not required for work. Reviews testify in favor of gypsum in terms of cost savings, due to its minimal consumption. Yielding in strength and moisture resistance to cement-sand compositions, they win in decorativeness and ease of application. But you can definitely choose which one is needed: gypsum or cement plaster, only when all external factors are taken into account.

Characteristics and properties

An important parameter is the consumption of material, cement mixtures are cheaper, but they are also required in a larger volume. When leveling significant surface deviations, it is desirable to calculate the thickness of the layer, in some cases it is more expedient to choose drywall. In particular, gypsum plasters are not suitable for creating layers over 50 mm (they are applied in several stages and dry for a long time), and cement plasters, in addition to complex and time-consuming pouring, will make the wall heavier. To determine which mixture is better, all working properties and operating conditions should be taken into account. The main parameters of binders are given below.

Summing up, it can be noted that cement mixture plasters are more suitable for outdoor work and cladding of rooms with high humidity, and gypsum plasters are more suitable for interior decoration. But we should not forget about exceptions: there are many compositions with modifying additives on the building materials market. They can accelerate the drying time of cement mortars and enhance their plasticity, insulating properties and decorative effect.

In turn, dry gypsum mixes are on sale for preparing walls in the bathroom (for example, Rotband), with their help, repairs in the sanitary zone are carried out in a matter of days. It is not worth giving unambiguous preference to any one material; before purchasing, carefully study its characteristics and conditions of use.

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 weak sides 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.

TO strengths 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 works, in apartments with draft and.

Advantages and disadvantages of gypsum coatings

Despite all the advantages of cement mortar, with interior decoration gypsum plaster confidently competes with him. 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 specifications 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 their positive traits, 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, for this decorative coating tiling is not recommended. When the adhesive comes into contact with 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 you to cover 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.