Gypsum-based dry building mixtures. Putties and grout

If you need to level the surface of the walls in a room or update the facade of the house, plastering the walls is one of the most inexpensive and popular methods. Of course, when starting work, you must first get acquainted with the types of plaster (especially in the case when there is not enough experience in the repair work), because choosing the wrong mixture can spoil the final result. In this article we will tell you how to prepare a cement-based plaster mix and dry gypsum plaster, as well as which type is suitable for walls.

Plaster walls

Let's compare cement-sand, lime and gypsum mortar for plastering walls in terms of characteristics.

Gypsum plaster

The most popular now are dry mixes for gypsum-based plaster. Their main advantage is the very simple application process. Such plaster is sold ready-made, you do not have to mix anything, you just need to dilute it with water in the required proportions.

The most popular plaster mix is \u200b\u200bfrom Knauf - Rotband, Volma Layer, Forman 10, Osnovit Gipswell, Prospectors. In terms of quality, they differ little from each other, but some types cannot be used in wet rooms.

Separately, it is worth talking about the universal mixes for plastering walls from "Knauf - Rotband". The price for a 30 kg bag is 360-390 rubles, which is more expensive than all similar options. On sale there is also packaging of 5, 10, and 25 kg.

This mixture has been produced for half a century in Germany, and in Russia it appeared 20 years ago. It became so popular that some people used to call any dry plaster mixes made of gypsum by the name “Rotband”.

There are other gypsum plasters from Knauf - Goldband and HP START, but they are not in demand due to their high density.

Rotband has the following characteristics:

Consumption 8.5 kg / sq. m. with a layer of 1 cm. One standard bag is enough for leveling 3.5 sq. x m.
The maximum layer thickness is 5 cm (on the ceiling only 1.5 cm, and if the height differences are greater, then the alignment is done with the help).
The minimum layer thickness is 0.5 cm (1 cm when laying tiles).
Average drying time is 7 days, depending on humidity and thickness.
Suitable for plastering walls and ceilings made of concrete, brick, expanded polystyrene surfaces.
This mixture is not suitable for sealing joints between drywall sheets. For this, a gypsum-based putty is used - Knauf Uniflot. Read more about in our article.
Recommended for use in rooms with normal air humidity, can be used in the kitchen or bathroom.
Color - from white to gray or even pink. It depends on the amount of natural impurities, and does not affect the characteristics of the material in any way.
Shelf life is 6 months.

You can apply a thicker layer to the walls after the first layer of maximum thickness is completely dry. On the ceiling, applying more than one layer of plaster is unacceptable.

Among the main advantages of the Rotband mixture are the following.

Getting a smooth surface.
No cracks even on a thick layer of plaster (subject to technology compliance).
The consumption of the mixture is two times less than that of the cement-sand species.
The ability to apply a layer up to 5 cm in one pass without spraying the surface.
The mortar does not lose all moisture even on porous substrates or at elevated temperatures, which ensures uniform drying without delamination and without cracks.
The composition does not contain harmful substances, it is completely safe.
Due to the addition of polymer additives to the composition, the mixture provides enhanced adhesion, which allows it to be used even on the ceiling.
The mixture contains special additives to increase the working time with gypsum mortar.

To obtain the optimal consistency, the dry mixture is mixed with water in proportions of about 2: 1, that is, 15-17 liters of water should be used per 30 kg bag. For thorough mixing, use a mixer attachment on a perforator.
The video shows an example of plastering work using Knauf Rotband:

Cement plaster mix

Cement-sand mixture for plaster has the following composition:

1 part of cement m-400;
3-5 parts of sand (if cement is m-500, then it can be increased to 7 parts of sand).

Usually during cooking add all the elements "by eye". You can use the following instruction.

The preparation of a solution for plastering walls begins with sifting the sand. This requires a sieve with meshes of about 4 mm; for dry sand, a finer mesh can be used. When the sand is ready, they begin to make the solution. To do this, pour 2.5-3 liters of water into a 10-liter bucket.

You can add a little detergent to the water to make the solution soft and pliable.

Put three parts of the cement in the mortar container and mix thoroughly with a mixer.
While stirring the solution with a mixer, add sand until the container is full. Start stirring the solution at low speed so that the liquid does not splash out.
As a result, the solution should turn out to be a viscous consistency, so that when the mixer is pulled out, a hole of 2-3 cm remains.

One batch is enough for you about 1.5 sq. m. walls. Basically, the consumption of the mixture depends on the thickness of the applied layer, so if you want to avoid overspending of the material, then you need to buy the thinnest beacons, from 3 mm.

Cement-based dry mix

If there are no plans to mix the solution yourself, you can buy a ready-made mixture in dry form, which is simply diluted with water.

For example, there are the following types on sale:

"Vetonit TT";
Volma Aquasloy;
"Magma";
CeresitCT 29 plaster and repair putty;
For facades: Knauf Unterputz, Zokelputz, Grünband (with expanded polystyrene granules), IVSIL GROSS.

Cement-lime mixture

Cement mortar in its pure form is not used so often, because it has poor adhesion and increased cracking. In addition, not everyone has the opportunity to use expensive dry mixes, so plaster with lime mortar is a good alternative. This is a very economical version of the mixture, which is convenient to work with due to its plasticity.

Also, this option is good for use in private houses due to its bactericidal properties - this is an additional protection against fungus. Lime mortar is chosen mainly for rough wall decoration in rooms with normal and low humidity. Unlike cement mortar, a lime-based mixture is well suited for plastering on shingles, as it adheres well to wood surfaces.

The disadvantages of this mixture include low brand strength, in contrast to the solution based on Portland cement. But this drawback does not play a special role; for plaster, compressive strength is not so much important as a good level of adhesion and plasticity.

Composition of lime mortar for plaster:

1 part cement;
½ part of slaked lime;
5 parts of sand;
300 ml of liquid soap.

The mixture is very flexible and adheres well to the wall; after drying, no cracks appear on the surface. Liquid soap adds a pleasant scent and increases elasticity.

Cement-lime mortar for plaster can be prepared in another way:

1 part lime sour cream;
2.5 parts of sand;
0.12-0.25 parts of cement (depending on the amount of lime).

It is best to take quicklime and extinguish it yourself. For 50 kg, you will need 13 buckets of water. Please note that when slaking lime will increase 2.5-3 times, so this work is done in a barrel of the appropriate volume.

This composition will adhere well and adhere to the wall, align with the rule and rub well. Plaster costs 250 sq. m. with such a mixture will cost about 22,200 rubles. (per material):

3 cubes of sand - 2000 rubles;
quicklime 800 kg - 19,000 rubles;
cement 150 kg - 1200 rubles.

If we compare the costs with the Rotband plaster, then the same area would take 3-4 thousand rubles more.

Dry mix on a lime-cement basis

You can buy ready-made dry mix on a lime-cement basis.
The following types are most popular:

Knauf Sevener (universal mix);
"BESTO";
"Founding STARTWELL" and "FLYWELL";

Facade plaster mixes

In private houses, in addition to interior decoration, external wall decoration is required. Many owners, unknowingly or in order to save money, plaster the facades with the same mixture that they used for interior decoration. It is strongly discouraged to do this, since external walls require a mixture that can withstand environmental influences without collapsing. Below we give a list of good plaster mixes for facade finishing.

Mineral plaster mixes

Mineral mixes are made on the basis of cement, therefore the packaging has a marking - "Polymer-cement mix". Thanks to such a component as redispersible powder, these mixtures have high adhesive qualities. Sell \u200b\u200bdry mineral mixtures in bags.

Mineral plaster
Specifications:

low cost;
fire resistance;
moisture resistance;
good strength;
high vapor permeability;
long-term operation.

Acrylic-based plaster mixes

Synthetic plaster mixes are based on acrylic dispersion. They are sold ready-made in a liquid state and do not require additional preparation.

Acrylic plaster
Specifications:

increased resistance to mechanical stress;
moisture resistance;
high adhesion to various surfaces.

Silicate plaster mix

The basis of silicate mixtures is potash water glass. Silicate mixtures are produced in liquid form, ready to use. This type of mixture is ideal for finishing walls insulated with mineral wool.

Silicate plaster
Specifications:

excellent elasticity;
good water resistance;
good strength.

Silicone plaster mix

As you can easily guess from the name, this type of mixtures includes an expensive material - silicone. For this reason, silicone mixtures are very expensive, but the price is perfectly compensated by the advantages of this material.

Silicone plaster
Specifications:

excellent moisture resistance;
long-term operation;
excellent adhesion;
high elasticity;
easy installation.

We examined the main types of plaster for walls, ceilings and facades. We advise you to carefully study the characteristics of each of them and choose the most suitable option. You can either buy a ready-made mixture, or prepare it yourself according to the above proportions.

Gypsum plasters are the name of a group of finishing materials that are used to decorate finishing coatings. Gypsum is hydrophilic, as a result of which it breaks down under the influence of water, therefore such materials are suitable only for interior surfaces in dry rooms.

The main element of this material, which binds all the others, is gypsum powder. It is made from a natural mineral that undergoes prolonged heat treatment and grinding. For the manufacture of plasters, gypsum of various fractions is used; the smaller the grain size of the mineral, the higher the quality of the treated surface.

In addition, the composition of the gypsum plaster includes a light fine-grained filler of natural or synthetic origin, as well as various polymer additives. The shape and size of the filler grains affect the appearance of the future surface. Also fillers significantly reduce the consumption of plaster and make the surface more durable. Polymer components increase the elasticity of the material, as well as its adhesion to various substrates.

Gypsum powder - the main component of plaster

Universal gypsum plaster is supplied as a powder mixture in paper bags of various weights. It requires water to prepare it. By adjusting the amount of liquid, you can change the fat content of the plaster, depending on the goals pursued. For finishing alignment on a pre-prepared surface or decorating the finished coating, a liquid solution is prepared, which will spread well on the wall. For sealing cracks, potholes or rough leveling, a denser mixture is prepared.

Gypsum plaster is supplied dry

General information

Below are the average technical characteristics of gypsum plaster, which may vary depending on the manufacturer and the materials used:

Operating temperature range - + 5 ... + 30 ° С.
The maximum layer thickness without reinforcing mesh is 5 cm.
Dilution proportions: dry gypsum plaster -1 part, water - 0.5 part.
The consumption of this material per square meter is 8 kg.
The setting time of the material is 1 hour.
Complete drying of the surface - 3 hours.
The curing time is 7 days.
Thermal conductivity of gypsum mixes - 0.23 W / m * C.

Advantages and disadvantages of plaster

This material has become widespread due to its positive properties:

95-97% gypsum plaster mix consists of materials of natural origin, which do not emit toxic substances when heated, wet.
After drying, a perfectly even coating of a pleasant shade is obtained, so further finishing with wallpaper, tiles or paint is not necessary.
High adhesion to almost all surfaces, due to which the material does not lag behind the wall.
The relatively small weight makes the work with the material comfortable, and also allows you to finish the ceilings.
The plasticity of the solution makes it easy to stretch it over the surface, which greatly speeds up and facilitates work.
Gypsum-based plaster does not shrink and therefore does not crack.
Vapor permeability ensures high-quality ventilation of the wall, thanks to which water will not accumulate under the layer of material.
Gypsum does not support combustion and does not burn, therefore it is an absolutely fireproof substance.

Gypsum plaster allows you to create a perfectly even coating

There are also some disadvantages:

Low moisture resistance, which is why the scope of the material is limited to dry rooms.
Do not cover with gypsum plaster surfaces with metal parts, as the material will constantly absorb moisture, which will lead to corrosion.
High price in comparison with other types of plaster.
Low mechanical strength.

What determines the expense

The consumption of gypsum plaster per 1 square meter is influenced by 2 main factors - the thickness of the layer and the evenness of the walls. With a pre-prepared or simply not very curved surface (blockage not more than 5 mm), the consumption of gypsum plaster is approximately 300 grams with a layer thickness of 1 mm.

Material consumption depends on the evenness of the surface and the thickness of the applied layer

For you can use the following example. Let's say there is a section of a wall with an area of \u200b\u200b1 square meter with a blockage of 3 cm. The first step is to weigh the surface at three points. In the first blockage is 0, in the second - 1.5 cm, in the last - 3 cm. Summing up the obtained values, we get 4.5 cm, divide by the number of values \u200b\u200b3, we get 1.5 cm - the average blockage. This is the thickness of the minimum leveling layer. After that, we multiply 15 mm of the layer by 300 grams of the solution required for a layer of 1 mm, we get 4.5 kg per square meter. Next, you need to take into account that there will be a decorative layer with a thickness of about 3 mm, it needs another 0.9 kg. The result is 5.4 kg, adding 10% for the stock and rounding up. As a result, this wall will require 6 kg of facade gypsum plaster or universal mixture.

A preliminary calculation of the plaster consumption allows you not to overpay for excess material

Self-preparation of the solution

There are three main types of material that can be made at home:

With sawdust. 4 parts gypsum, 1 part sawdust, 1 tile adhesive.
Plaster-chalk solution. 1 part gypsum, 3 parts crushed ground chalk, 5% wood glue from the total mass of the mixture.
Lime-gypsum solution. 1 part gypsum, 1 part lime dough.

The cooking rules are as follows:

Measure out portions of the components in special containers.
Mix dry ingredients.
Add some water and mix with a construction mixer or drill with a nozzle.
Leave to infuse for 3 minutes, then mix again.

To prepare the solution, you should have a construction mixer or drill with a special attachment at hand

On a note! These instructions are suitable for commercial mixes and hand-made dry ingredients. For a lime-gypsum solution, gypsum is first soaked with water, mixed, and then added to the lime dough.

Preparing walls for plastering

Before roughing the walls with plaster compounds, the following steps must be taken:

Remove the old coating and clean the surface from grease stains, dust, wallpaper and paint residues.
Tap the surface with a hammer to identify weak wall fragments and remove them.
Seal cracks, potholes and chips with polyurethane foam or cement mortar.
Prime the walls 2 times with an interval of 4 hours.

Stages of surface preparation for applying gypsum plaster

Important! With a large thickness of the applied gypsum mixture, it tends to quickly fall off, therefore, the installation of a reinforcing mesh is required.

Mesh installation:

First of all, markings are applied to the wall - dots every 40 cm.
Holes are drilled in the marked places and dowels are installed.
Using metal scissors, cut the mesh into fragments of the required area and shape.
Attach the product to the wall and fix it with self-tapping screws.

Installation of a reinforcing mesh is necessary when applying a large layer of plaster

If the mesh is loose or vibrates when touched, it is necessary to additionally reinforce it with wire passing it through the Z-shaped cells.

The procedure for applying gypsum plaster

The prepared solution should be applied in one layer no more than 5 cm thick without a grid, no more than 8 cm with a grid. A solution is collected on a trowel or spatula and transferred to the surface, after which it is stretched with a trowel or spatula. Then you need to take a rule and level the material. To do this, the tool is applied to the bottom of the wall and carried upward, while making zigzag movements.

You should know! The application of gypsum plaster, which has remained on the blade of the rule, is impossible, since it dries very quickly.

1 hour after applying the solution to the entire wall, it is necessary to treat the surface with a trapezoidal rule. Then all irregularities are putty and smoothed out with a wide spatula. Traces from the rule can also be smoothed out with a spatula. The next procedure should be started after about half an hour. But if the surface is pressed with a finger, then you need to wait a little more time.

The procedure is as follows:

The surface is abundantly wetted with water.
Wait until the wall is matte.
Take a spongy float, press it against the wall and carry out circular movements.
Smooth the entire coating with a wide spatula.
Wait 5-7 hours and repeat the procedure.

Surfaces plastered in this way do not require subsequent filling.

This completes the plastering. Additional procedures are no longer required, but there is a need to provide comfortable conditions for the solution to dry. The room should be free of drafts and working heating devices. In addition, coverings should be protected from direct sunlight. After 3 days, it is necessary to ventilate the room to remove excess moisture. Temperature range - + 5 ... + 25 degrees.

How to apply plaster with a machine

In the modern construction market, you can find equipment such as plastering machines. It should be noted right away that it is quite expensive, so for one-time or short-term use it is better to rent it. The device consists of a container into which a ready-made solution or components for it are loaded, a supply hose, a nozzle for controlling the intensity of material supply. There is also a power cable, a compressor and a setting panel.

Machine method for applying gypsum plaster

The procedure for applying plaster:

Load the finished mixture into a container.
Connect the equipment to the network and pick up the supply hose.
Direct it to the wall, while holding it 30 cm from the surface to be treated.
Turn on the plaster feed and move from bottom to top.
The layers of material should overlap each other.
At the end, the material is leveled and rubbed in the same way as in the case of the usual application.

How much gypsum plaster dries

In a well-ventilated room, subject to the temperature regime, complete drying and strength gain of the material occurs in 7-14 days. After complete drying, the coating acquires an even light color. At this stage, you can proceed with further finishing. If a tile was chosen, then you can simply apply glue and mount it. If painting is planned, then the moisture content of the wall can be no more than 1%.

Complete drying of the plastered surface occurs in 7-14 days

Important! Acceleration of drying of coatings using heating devices is prohibited.

Basic requirements for the quality of gypsum plaster

The main requirement is a perfectly flat surface without cracks, chips, dents and dents. This is quite simple to achieve - just make the right solution and dry the walls. If the color of the wall becomes uneven after drying, it means that slightly different solutions were prepared. To correct this error, you will have to reapply a thin decorative layer to smooth out the color.

The formation of cracks in the plaster indicates an improperly prepared solution or forced drying of the finished surface

The surface should contain subtle pores, if there are none, the vapor permeability will be lower than the technology requires. If the pores are too large, then the solution was poorly mixed. This can be corrected with a layer of decorative plaster.

On a note! The quality of the coating should not be judged in poor lighting conditions.

It is very easy to prepare and apply this material. It is enough only to observe the composition of gypsum plasters, and also carefully read the description of the material and its technical characteristics, which are indicated by the manufacturer.

Regardless of the type of repair (cosmetic or major), a process such as plastering walls is required. It is safe to say that these works are the most time consuming and expensive. They cannot be performed without the use of special dry mixes.

There are several types of this finishing material, but gypsum plaster mixes are of the highest quality, reliable and easy to use.

As the name implies, the basis of the material is gypsum.

In addition, you can also highlight the following main components that make up the gypsum plaster:

Filler. It has a light structure and consists of fine fractions. The presence of the filler ensures the stability of the shape and structure of the plaster. As a result, gypsum plaster mixes are extremely economical to use.
Polymers... They give the mixture properties such as elasticity and impermeability. In addition, the presence of polymers guarantees a high adhesion of the mixture to the working surface.

The composition of gypsum plaster allows you to use it for the following purposes:

Masking and patching up a variety of defects and irregularities on the surface.
Formation of slopes and corners (see).
Aligning walls that have a heaped corner.

Note. The plaster mix is \u200b\u200bavailable as a dry powder, packed in convenient and sealed bags.

Main advantages

This is clearly seen in the table below:

Types of plaster	Cement	Gypsum	Result
Properties
Light weight	–	+	The mixture adheres perfectly to the surface, does not form sagging, it is possible to use the machine method of laying, high speed of work
No need for post-treatment of the mixture on the surface	–	+	Immediately after the layer of putty has hardened, surface finishing can be started
Short curing time	–	+	The time required for finishing works is significantly reduced
Low density	–	+	Minimum consumption of working material is ensured
Does not shrink	–	+	No cracks form after the mixture dries
Sustainability	–	+	Promotes a beneficial and healthy indoor climate

Note. From the foregoing, it follows that gypsum plaster mixes are the most economical and convenient type of dry plaster, the price of which is available to every customer.

Using

You can familiarize yourself with the cooking process from the instructions on each package.

Stages of work

First of all, you should pay attention to the indoor temperature. It should be within + 5 + 30 degrees Celsius.
Before starting finishing work, it is necessary to prepare the surface: By cleaning it from dust, old plaster (see How to remove old plaster from walls without problems), dirt.

It is also required to remove all foreign objects:

Nails.
Hooks.

Council. If it is not possible to remove them, they must be treated with a special anti-corrosion liquid.

The surface on which the gypsum plaster mix will be applied must be treated with a primer:

If the work surface strongly absorbs moisture, for example, aerated concrete or brick, it will have to be primed several times.
This is necessary in order to ensure good adhesion of the mixture to the surface.

Now you can start preparing the solution:

To do this, the powder from the package is poured into a deep container and filled with clean water at the rate of 0.6 - 0.8 liters of water per 1 kg of dry powder.

If such devices are not available, you can also interfere manually. I would like to note that the prepared mixture must be used within 30 minutes.
Otherwise, the solution will begin to dry out and become unusable for further use.
It should also be noted that foreign components should also not be allowed to enter the finished plaster.

Note. This can disrupt its composition, which, as a result, will lead to the fact that it loses its properties.

The gypsum plaster mixture is applied to the surface with a layer, the thickness of which ranges from 50 to 79 mm:

Work must start from top to bottom. After the layer of plaster has been laid, it should be leveled.
To do this, you can use a special tool - a rule that has the shape of the letter h. After an hour, remove excess plaster as a rule.
You can finally level the plastered surface using a construction trowel with a wide base.

If there are no traces left, it must be abundantly wetted and rubbed with a sponge float. This should be done with neat circular movements.
To achieve the most even plaster surface, this procedure can be repeated after about 24 hours.

Note. One of the advantages of this solution is that plastering with a gypsum mixture eliminates the need for subsequent processing of the working surface.

For quick and high-quality drying of the solution, it is necessary to completely exclude the presence of drafts in the room.
In addition, you should also not allow direct sunlight to hit the surface.
The final stage of the work is to ventilate the room. Thus, excess moisture is removed from it.

The video in this article will visually introduce you to the stages of working with gypsum plaster.

What to look for when choosing a material

When buying gypsum-based plaster (gypsum plaster mix), experts recommend paying attention to its manufacturer. There is a fairly large selection of such mixtures on the market for building and finishing materials. A positive result can be achieved only if the product is released by a well-known company whose products have received positive user reviews.

Gypsum plaster mixes are produced by the following brands:

Baumit;
Knauf (see Knauf facade plaster: material characteristics);
Lithox;
Polirem;
ArtEko, etc.

According to experts, the best quality and most reliable plaster mixes are Knauf. Both an experienced and a novice master can work with it with ease.

For gypsum-based plaster produced by this manufacturer, the following positive properties are inherent:

Uniform mix of dry powder with water.
The ability to use for finishing various surfaces: brick, their gas - or foam concrete, tile, concrete, etc.
Lack of shrinkage and, as a result, cracking after drying.
Economical consumption of working solution.
The most even distribution on the surface.
Information on the minimum period required for finishing work.
Environmental friendliness.

Note. It is also important that the Knauf gypsum plaster mix has such a property as sound insulation. This is extremely important. If finishing work is carried out in the premises of a panel house, where there is poor sound insulation.

At the end

This became possible due to the fact that in the production process such an environmentally friendly natural component as gypsum is used as a basis.

As a result of the use of special additives, gypsum plaster mixes produced by this brand do not spread on the surface. This makes it possible to use them when working on a surface located at an angle, to finish or level slopes and corners.

Choosing a plaster of this manufacturer, you can be completely sure that the mixture will perform all the functions assigned to it, and the work surface will have an attractive appearance for a long time.

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Introduction

At present, in connection with the increasing scale of the introduction of progressive technologies that reduce fuel, energy and material resources, the advantages of gypsum binders are becoming more significant and their scope is expanding. In this case, the stability of the quality of gypsum binders is especially important in order not to disrupt the technological mode of production of materials and products based on them.

Quality, reliability and durability are the main requirements for building materials today. Modified dry mixes, which have become an integral part of modern construction, meet these requirements most fully.

Dry building mixtures (CCC) are a mixture of binders, aggregates and various additives.

Currently, dry building mixtures based on gypsum binder are widely used. Gypsum materials have sufficient compressive and flexural strength, high heat and sound insulation properties. Products made from gypsum binder, due to the natural properties of gypsum to absorb and release moisture, provide an optimal level of humidity in living quarters. The formulations of most types of dry building mixtures provide for the use of plasticizing, water-retaining additives and redispersible polymer powders.

One of the promising directions in solving environmental problems associated with the storage of gypsum is the development and implementation of technological processes that make it possible to obtain construction gypsum binders and materials based on them. This, in turn, will allow not only to reduce the alienation of land, pollution of soil, air, ground and surface waters, but also to expand the range of products of the construction complex.

Increasing the consumer level of materials is one of the leading principles of Kazan Dry Building Mixes Plant LLC. The goal of the company is to implement a functional, efficient, competitive customer-oriented business, taking into account and knowing the needs of its partners and employees, taking a leading position in the building materials market. The work involves the most modern science-intensive and expensive technologies for the production of dry building mixtures. This makes it difficult to compete with the plant, as it has already firmly established its position in the market and is a leader. The huge scale of production makes it possible to keep prices at a level that is affordable for every buyer and difficult for competitors.

Providing customers with a wide range of high quality products at prices below the market average with the widest possible range of related services, as well as creating a system of the best offer - the basis of the strategy of LLC "Kazan plant of dry building mixtures".

The main areas of activity are:

Production of building materials and individual components;

Sales of the company's finished products through its own network of stores, as well as to wholesalers from the factory;

The market of dry building mixtures in Kazan can be considered very saturated, and competition is tough; in general - a situation that does not favor the emergence of new large players in this market in the near future. Barriers to entry are not high, but difficult to overcome, and therefore there are almost no small firms in this market.

Dry construction mixtures are a fairly easily transportable product, however, this market also has its own geography - no more than 500 km. This is due, first of all, to the fact that dry mixes are, as a rule, a large-tonnage product and have a not very high cost; logistics costs for transportation over longer distances increase the price of the product by 30-40%.

Expanding the use of dry mixes is another step in modern construction technology aimed at improving the quality and reliability of construction work. Currently, a great variety of dry mixes are presented on the Russian market. Many mixtures are produced in Russia, others are imported from abroad. Dry building mixes require certain skills from the builder and strict compliance with the instructions for use of each mix. Without these conditions, the properties of the mixture declared by the manufacturer may not be obtained. And on the other hand, the production of high quality dry mixes is a rather complicated process that requires special equipment and careful adherence to technological regulations.

1. Characteristics of gypsum-based dry building mixtures and their composition

The range of gypsum binders produced in the country for construction work is limited to building gypsum produced in accordance with GOST 1 25-79 with a strength range from 3 to 7 MPa.

Anhydrite binder, which is very promising due to the low cost of raw materials and low investment in processing, has not yet found sufficient distribution. Such a binder has the same positive properties as other gypsum binders, and even surpasses in final strength. It can be used for the same purposes as gypsum binder, including for the production of dry building mixtures.

Building mixtures made on the basis of gypsum or anhydrite binders are called dry gypsum mixtures (SGS).

A distinctive feature of mortars based on gypsum dry mixes, in comparison with cement slurries of a similar purpose, is the increased yield per unit mass of dry mix. The use of gypsum dry mixes for finishing provides a reduction in labor costs by more than 2 times, and the consumption of the mix is \u200b\u200balmost 2 times lower than that of a cement mix for the same processing area.

SGS are homogeneous bulk materials of optimal composition, consisting of carefully metered and mixed dry components - gypsum binders. Fractionated fillers (fillers), pigments and modifying additives for various purposes.

In accordance with the existing classification, the GHS can be subdivided into the following main types:

· Plastering (including decorative and protective);

· Putty;

· Assembly;

· Trowelling;

· Floor (leveling for the floor device).

Mixtures based on non-waterproof gypsum binders are used for interior decoration of buildings and structures with dry and normal room conditions, and SGS based on water-resistant gypsum binders for finishing work in rooms with normal, wet and wet conditions, as well as for finishing building facades in accordance with the current regulatory documents SNiP 3.04.01-87, SNiP 2.03.13 - 88, SNiP P -3 - 79.

Gypsum binders are divided into two groups: low-fired and high-fired.

Low-calcined gypsum binders are obtained by heating the two-water gypsum CaS04-2H20 to a temperature of 150 ... 160 ° C with partial dehydration of the two-water gypsum and transferring it to the semi-aqueous gypsum CaSO4-0.5H2O.

High-calcined (anhydrite) binders are obtained by calcining gypsum dihydrate at a higher temperature up to 700 ... 1000 ° C with complete loss of chemically bound water and the formation of anhydrous calcium sulfate - anhydrite CaS04. Low-fired gypsum includes construction, molding and high-strength gypsum, and high-fired gypsum - anhydrite cement and estrich gypsum.

The water resistance of gypsum binders is assessed by the softening coefficient, according to which gypsum binders are divided into:

Non-waterproof (HB);

Medium water resistance (CB);

Increased water resistance (PV);

Waterproof (B);

Increasing the water resistance of gypsum binders is possible through the implementation of the following technological solutions:

Increasing the density of products due to their manufacture by tamping and vibrocompression from low-plastic mixtures;

Increasing the water resistance of gypsum products by external and volumetric hydrophobization, impregnation of products with substances that prevent moisture penetration into them;

The use of chemical additives, including plasticizing ones, allowing to modify various properties of gypsum concrete;

Reducing the solubility of calcium sulfate in water and creating conditions for the formation of insoluble compounds that protect calcium sulfate dihydrate by combining gypsum binders with hydraulic components (lime, Portland cement, active mineral additives).

Nature is the raw material for the production of gypsum binders. gypsum stone and natural anhydride CaSCu, as well as chemical industry waste containing dihydrate or anhydrous calcium sulfate, such as phosphogypsum. It is possible to use gypsum-containing natural raw materials in the form of soot and clay gypsum.

Gypsum binder is an air binder consisting mainly of semi-aqueous gypsum and obtained by heat treatment of gypsum stone at temperatures of 150 ... 160 ° C.

The dihydrate gypsum CaSCVFbO contained in the gypsum stone dehydrates according to the equation:

CaSO4-2H2O \u003d CaSCv0.5H2O + l, 5H2O.

Plastering gypsum mixtures.

Plaster mixes are mortar mixes of non-water resistant gypsum binders of B- or a-modifications, anhydrite or their mixtures, coarse-grained aggregate with a fraction of not more than 2.5 mm and special chemical additives for various purposes. Such mixtures are intended for rough leveling of surfaces by single-layer plastering of walls and ceilings with various types of surfaces (concrete, brickwork, cellular concrete, other rough and corrugated surfaces).

The most famous types of gypsum plaster mixes include: ROTBAND, GOLDBAND, GIPSPUTZ HP 100, MASHI-NENPUTZ MP 75, AKUSTIKPUTZ, TEPLON, SILIN, FARVEST-Gips, Gypsum white, Gypsum gray, etc. CONS.

Gypsum plaster mixes and solutions from them should be characterized by the following indicators:

b the bulk density of the mixture, kg / m3 -700 ... 1100;

b water-solid ratio (the amount of mixing water required to obtain a given mobility of the solution) -0.5 ... 0;

b solution processing time, min. -50 ... 100;

b density of the hardened solution, kg / m3 -800 ... 1100;

b compressive strength, MPa - 2.5 ... 7.0;

b bending tensile strength, MP - 1.5 - 3.0;

b adhesion strength with the base (processed surface), MPa - 0.4 ... 0.7;

b shelf life, months - 3 ... 6

The indicators of these properties depend on the field of application of the solution and its composition.

Putty gypsum mixtures.

Putty mixtures are dispersed mixtures of non-water-resistant gypsum binders B- or a-modifications, anhydrite or waterproof gypsum binders (gypsum-cement-pozzolanic or composite gypsum binders), fine and finely dispersed fillers and chemical additives for targeted purposes.

Such mixtures are intended for thin and final leveling of walls and ceilings surfaces; for final preparation of concrete and plastered surfaces for painting or wallpapering; for facing and restoration work. They are used for sealing longitudinal and transverse joints between gypsum boards and gypsum plasterboard during interior finishing work, as well as joints when installing gypsum tongue-and-groove plates. They have good adhesion to various materials and practically do not shrink. The advantage of gypsum fillers is their quick hardening, which allows further finishing work after several hours of hardening.

The most famous types of plaster putty mixtures include: UNIFLOT; FUGENFULLER; FUGENFULLER Hydro; FUGENFULLER GW; FUGENFIT; FINISHING; UNIS GSh; GSh Slide; UNIS Blik; P-16 MONOLITH; R-1 7 MONOLITH; GLIMS-Gypsum; PETRO-MIX SHG; SHGL; SHGS; ShGU; KREPS GKL, etc.

Plaster putty mixtures are characterized by the following properties:

b compressive strength, MPa - 4 ... 1 0;

b bending tensile strength, MPa - 2.5 ... 5;

b shelf life, months - 3 ... 6

Dry gypsum mixes (assembly).

Mounting mixtures are mortar mixtures of non-waterproof gypsum binders of p- and a-modifications or waterproof gypsum binders (gypsum-cement-pozzolanic or composite gypsum binders) with a specially selected complex of chemical additives.

Such mixtures are used when installing internal partitions from gypsum groove-ribbed plates; when lining internal surfaces with gypsum plasterboard and gypsum-laminated sheets, as well as when constructing bases for floors made of gypsum-fiber boards.

The most famous types of gypsum assembly mixtures include: PERLFIX, ("KNAUF"), GIPSOKONTAKT ("Bolars"), VOLMA montage (JSC "GIPS", Volgograd), etc.

The main physical and technical characteristics of some types of gypsum assembly mixtures are as follows:

bulk density, kg / m3 - 800 ... 950;

b water-solid ratio - 0.4 ... 0.6;

b solution processing time, min. - 60 ... 120;

b density of the hardened solution, kg / m3 - 1300 ... 1350;

b compressive strength, MPa - 4 ... 7.5;

b bending tensile strength, MP - 1.5 ... 5;

b adhesion strength, MPa - 0.3 ... 0.7;

b shelf life, months - 6.

Floor dry gypsum mixes (leveling).

Dry mixes for flooring are mortar mixes of non-water resistant gypsum binders a-modification, anhydrite, estrich-gypsum or waterproof gypsum binders (gypsum-cement-pozzolanic or composite gypsum binders) and a special set of chemical additives to increase the plasticity of the solution while reducing the water content.

The most famous types of gypsum mixes intended for floor foundations are ATLAS SAM 200 mixes, Alfa-Pol S self-leveling compound, Fast-hardening floor (Prospectors), SV-210 floor mix (Bolars), etc.

Dry mixes for self-leveling floors are known as self-leveling compounds: Flisestrich FE 80, Flisestrich FE 50, Flisestrich FE 25, which are produced by KNAUF enterprises. The hardened solutions from these mixtures are highly durable and practically do not shrink.

The main physical and technical characteristics of some types of gypsum leveling mixtures for flooring are as follows:

bulk density, kg / m3 - 600 ... 700;

b water-solid ratio - 0.48 ... 0.6;

b solution processing time, min. - 60 ... 120;

b density of the hardened solution, kg / m3 - 1100 ... 1800;

b compressive strength, MPa - 4 ... 10;

b bending tensile strength, MPa-2.5,., 5;

b adhesion strength, MPa - 0.3 ... 0.5;

b shelf life, months - 3 ... 6.

Currently, on the territory of Russia, there is no single standard governing the requirements for indicators of the physical and technical properties of CCS. The requirements for mortar mixtures and solutions in GOST 28013-98 *, SP 82-101-98, SNiP 3.04.01-87 do not cover all the features of the properties of dry mixes for various purposes that have appeared in our country over the past decade. Quality control at the leading domestic enterprises for the production of dry mixes is carried out on the basis of technical specifications developed taking into account existing European standards, for example, EN 12004 for adhesive dry mixes and solutions, as well as indicators of the physical and technical properties of modern domestic and foreign analogues.

In this work, the main indicators of TU 5745-001-57228332-2006 of OOO Kazan Plant of Dry Building Mixes are taken as the regulatory requirements for the indicators of the physical and technical properties of the developed adhesive dry mixes.

2. Raw materials of gypsum-based dry building mixtures

For the manufacture of GHS, the following basic materials and additives are used: gypsum binders of the G4-G7 grades in accordance with GOST 125-79 (for plaster and putty mixtures during finishing work):

· High-strength gypsum of grade not lower than I 3 in accordance with GOST 125-79 (for high-strength putties and compositions for installation work, as well as in compositions for self-leveling floor screeds); waterproof gypsum binders according to TU 21-0284757-1-90 (for dry gypsum mixes used in rooms with wet and wet operation, as well as for floor mixes); anhydrite binders (from natural raw materials and industrial waste) according to TU21-0284747-1-90 (for plaster mixes and leveling mixes for flooring);

· Hydrated lime according to GOST 9179-77 (sieve residue 02 up to 0.2% by weight). Moisture up to 0.5% by weight (in plaster and self-leveling mixtures for flooring).

Fillers and fillers have a great influence on the properties of GHS. The choice of aggregate grain size is determined by the type of gypsum mixture: quartz and limestone sands are used with a fineness of up to 0.8-1.0 mm. When selecting aggregates, special attention is paid to the granulometric composition: there should be approximately the same ratio of aggregate fractions.

The following aggregates and fillers are used in the SGS:

· Expanded perlite sand according to GOST 10832-91; the residue on a sieve with a mesh size of 1.25 mm - less than 10% by weight. Bulk density - from 70 to 1 25 kg / m3; used in compositions of heat-insulating or lightweight plaster mixes;

· Expanded vermiculite sand according to the current normative and technical documentation;

· Quartz sands in accordance with GOST 21 38-91, the residue on sieve No. 05 is less than 10% by weight. Moisture less than 0.5% by weight; used in plaster mixes and leveling mixes for flooring;

· Mineral powder for asphalt concrete mixtures in accordance with GOST 16557-78, the remainder on the sieve No. 0315 is less than 10% by weight. Humidity not more than 0.5% by weight; used in the composition of plaster and putty mixtures.

Chemical additives for gypsum mixtures must meet the requirements of GOST 24211-91. These include the following additives:

· Water-retaining on the basis of cellulose ethers methyl cellulose brand MC-100 (Russia); ethyloxyethyl cellulose, EOEC (Sweden); sodium salt of carboxymethyl cellulose, (CMC), (Russia).

Based on cellulose esters (methylhydroxyethylcellulose, (MHEC), (Germany, USA); methylhydroxypropylcellulose (MHPC), (South Korea);

· Air-entraining anionic surfactants (Russia, Germany); olefin sulfonate (FRG);

· Thickening based on starch ether (Russia, Germany); based on hectorite clays (Italy);

· Plasticizing naphthalene formaldehyde, for example S-3 (Russia); melamine formaldehyde (FRG); polycarboxylate (FRG);

· Redispersive polymer powders: based on vinyl acetate copolymers (Germany, Switzerland, USA, France). Based on styrene butadiene latex (FRG); based on acrylate (FRG);

· Defoamers - additives that are hydrocarbons and polyglycols on an inert carrier (amorphous silica).

In the manufacture of SGS, the correct choice of additives that regulate the beginning and end of setting, especially those intended for the production of plastering, is of great importance. In this case, it is necessary to take into account not only the type of gypsum binder, but also the pH-medium of the prepared gypsum solution.

For a neutral medium of a gypsum solution, citric acid, sodium citrate, polyphosphates, protein hydrolysates, gelatins - CMC (sodium salt of carboxymethylcellulose), adhesives of animal origin, a mixture of lignosulfonates can be effective set retarders. However, it should be borne in mind, for example, that retardan, being an active retarder for the setting of gypsum, is very well suited for putty compositions. At the same time, it is not effective enough for plastering compounds, because gives a short period between the beginning and the end of setting, which is undesirable in the production of plastering works.

For gypsum solutions with an alkaline medium, tartaric acid, as well as a retarder based on tartaric acid and plastretard, are effective set retarders.

For a weakly acidic environment, for example, in plaster solutions based on a gypsum binder made of phosphogypsum, hydrated lime and sodium tripolyphosphate are used as setting retarders.

To achieve the required retardation of the setting of the gypsum solution, it is advisable to use a complex additive. A typical example is plastretard - a mixture of citric acid with polyphosphates and gelatin.

To reduce cracking and shrinkage deformations, cellulose fibers are introduced.

Putty, grouting mixtures, and gypsum adhesives differ from plaster compositions, both in the component composition and in its dispersion. A feature of these compositions is that as a binder used stucco with a particle size of less than 0.1 mm, the filler is limestone, dolomite flour, chalk with a grain size of less than 0.1 mm. In this regard, the number of water-retaining additives increases to 0.5-0.8%, while in plaster compositions - 0.16-0.3%.

Water-retaining additives based on cellulose ethers are of great importance in dry-chemical systems, including SGS. Studies have shown that due to the weak intermolecular interaction with water molecules, these polymers have excellent water retention ability. Each polymer molecule can hold up to 20 thousand water molecules. The energy of this interaction is comparable to the energy of evaporation and capillary diffusion into the base, which is an obstacle to water escape. In turn, this energy is somewhat less than the diffusion energy of water during cement hydration, which allows it to take this water.

In fact, the water in the solution is replaced by a homogeneous gelatinous methylcellulose solution in which particles of cement and aggregate are suspended. The high water-holding capacity of such a system contributes to the complete hydration of the cement and allows the mortar to gain the necessary strength even with thin-layer application. After the water leaves, the polymer in the form of the thinnest film remains on the surfaces between the cement stone and the filler, without affecting in any way the mechanical characteristics of the hardened mortar. Thus, the addition of a small amount (0.02-0.07%) of water-soluble cellulose ethers to cement-sand mixtures leads to a significant increase in the open time and allows the solution to hydrate evenly throughout the volume, and also provides a significant increase in adhesion to the base and improvement surface quality. The action of methylcellulose is similar in gypsum mixtures.

Dispersion powders, which, unlike water-soluble cellulose derivatives, when mixed with water, form not solutions, but two-phase systems consisting of polymer particles (based on copolymers of vinyl acetate and ethylene, vinyl chloride, styrene acrylate, etc.) dispersed in water. The addition of these formulations to construction chemicals allows you to actively influence the characteristics of the final material and provides results that are unattainable when using only traditional mineral binders. The first attempts to modify cement mixtures with polymers consisted of adding to the mixing water a dispersion of vinyl acetate, known as PVA glue. In gypsum mortars, this application turned out to be very effective, while in cement mortars (due to increased shrinkage from the use of PVA), they quickly abandoned. The next step was the use of two-component compositions consisting of a cement-sand mixture prepared in the factory and a polymer dispersion supplied in liquid form, which are mixed at the construction site. Two-component solutions are still used, but the aqueous dispersion loses its properties when freezing, therefore, in the cold season, its transportation and preparation of the working solution cause certain difficulties. The beginning of the production of one-component dry building mixtures dates back to 1953, when the specialists of the Wacker company (Germany) managed to obtain a dry redispersible powder, which, after mixing with water, forms a two-phase system with the properties of the initial polymer dispersion.

Dispersions differ from methylcellulose in their mechanism of action. As it is consumed, the water is concentrated in the pores of the cement stone and the dispersion is concentrated there, forming "elastic bridges" that work in tension and bending incomparably better than cement. The combination of mineral and polymer binders makes it possible to produce construction chemistry products that have not only increased strength properties and improved adhesion (including to such "problematic" substrates as metal, wood, plastic, glazed tiles, etc.), but and controlled rheological (thixotropy, plasticity) and special (hydrophobicity, fluidity) characteristics. For example, leveling solutions for floors contain a combination of special dispersion additives with organic and synthetic plasticizers, the presence of which determines such specific properties of these materials as the ability to spread and the smoothness of the resulting surface. Dispersion modifiers, which are part of adhesives for tiling, improve working conditions, extend the "life" of the mixed solution and increase the thixotropy (the ability to thicken at rest and liquefy with stirring) of the material. They help to improve adhesion to difficult substrates.

State Unitary Enterprise "NIIMosstroy" develops a formulation of gypsum dry mixes by orders of enterprises, conducts tests of all types of dry building mixes, including certification. For this, the laboratories of the institute are equipped with modern instruments and equipment, incl. for testing binders according to European standards. Moreover. The NIIMosstroy Certification Center certifies products and quality management systems.

Dry mix fillers.

The filler is introduced to reduce the cost of the product, but most importantly - to prevent cracking during operation. In addition, its use improves workability during application. Quartz sand, as well as limestone flour, dolomite flour, chalk, and ash are used as fillers in gypsum mixtures. Perlite is used in the composition of lightweight plasters - for example, in such mixtures as HYPER PLAST (the name of this mixture comes from the combination of the words GIPPS and PERLIT). In certain types of putty mixtures, the use of mica is recommended. The dispersion of the aggregates is determined by the type of gypsum mixture: quartz sand and limestone sand are used with a dispersion of up to 0.8-1.0 mm. When selecting aggregates, special attention is paid to the granulometric composition: there should be approximately the same ratio of aggregate fractions.

Hydrated lime Ca (OH) 2 is introduced into the composition of gypsum mixtures to improve plastic properties, reduce shrinkage deformations and slow down the setting.

Quartz sands of the Arakchinsky quarry (Kazan) and the sand of the quarry of the OJSC "Combine of nonmetallic materials" (Kazan) are used as initial ones. The specified grain size composition of the sand is obtained on the basis of pre-dispersed standard fractions of the original sand. The content of dusty and clayey impurities of both sands is within the permissible values \u200b\u200baccording to GOST 8736-93.

Functional additives for dry mixes.

All studied supplements can be divided into three groups:

Strengthening additives that can replace 20% of cement while ensuring the specified strength of concrete.

Stabilizing additives that can be added in an amount of 20% to the standard cement consumption to guarantee the required concrete strength.

Finely ground mineral additives that reduce the strength of concrete and are not recommended for practical use.

Functional additives slow down the setting rate of the gypsum mixture, increase its water retention, mobility, plasticity, adhesion strength, and reduce the risk of cracking.

Set retarders are important functional additives that increase the vitality of the mortar gypsum mixture. It is known that gypsum binders set quickly, and the solution to the problem of increasing survivability lies in the correct choice of special additives - set retarders.

Cellulose fibers are added to gypsum mixes to reduce cracking and shrinkage deformations.

These are the lightest and most convenient formulations to work with. Their only drawback is that they can only be used indoors in dry rooms.

Increasing the water resistance of dry building mixtures.

In the practice of finishing works, lime-based dry mixes are often used, which, due to the high vapor permeability of coatings, provide an optimal microclimate of buildings and structures. However, insufficient water resistance and strength of lime coatings hinder the wider use of lime-based dry mixes in outdoor decoration. The existing methods for increasing the water resistance of lime composites, for example, the introduction of cement into the formulation, lead to a decrease in the vapor permeability of the coatings and, as a consequence, to a decrease in the service life.

A technological solution to improve the performance properties of coatings based on lime-based dry mixes is the introduction into their formulation of components that have high water resistance and are able to regulate the structure formation of the material. Such substances include calcium hydrosilicates (HSC), the rational form of introduction of which are dispersed phases (mineral filler). The synthesis of a mineral filler based on HSC can be carried out from sodium hydrosilicates (water glass) in the presence of a precipitating additive. The activity of the fillers depends on the drying temperature.

The most active is the filler dried after filtration at a temperature of 300 ° C. Compressive strength Rc of specimens at the age of 28 days of hardening in air-dry conditions of the composition 1: 0.3 (lime: filler) by weight with a water-lime ratio W / I equal to 0.65 when using a filler dried at a temperature of 300 ° C , is Rc \u003d 10.4 MPa, and the composition with the use of a filler dried at a temperature of 105 ° C is 5.9 MPa, i.e. the increase in compressive strength is 100%.

The use of dilute solutions slows down the precipitation and the appearance of larger crystals. So, with the introduction of the CaCl2 precipitating additive in the form of a 7.5% solution, the content of particles with a size of 0.05-5 microns is 5.58%, and for particles with a size of 10-45 microns - 53.46%.

Less than 5% are particles with a diameter of 6.7 microns. The content of particles with a size of 45-100 microns is 32.62%, crystals with a particle size of 100-200 microns appear, their content is 0.04%. The use of such a filler in lime compositions contributes to the formation of a less durable structure.

The study of the hygroscopic properties of the fillers showed that they have a high sorption capacity. So, at a relative humidity of 72%, the sorption humidification after 10 days is 20%, and at a relative humidity of 100-95%.

The use of a filler based on HSC in the formulation of lime-based CCC helps to increase the water resistance of composites based on them. It was found that the softening coefficient of the control samples is Krazm \u003d 0.42, and for samples with the use of GSK - Krazm \u003d 0.54. The samples with the addition of Kratasol PFM and S-3 have a higher value of the softening coefficient, the water resistance of which is respectively Krazm \u003d 0.57 and Krazm \u003d 0.63.

The development of the formulation of dry mixes is a complex and lengthy process that requires the participation of qualified personnel and the mandatory availability of a modern laboratory for research and testing of samples of solutions from dry mixes, equipped with modern equipment.

3. Technological scheme for the production of dry building mixtures.

The technology for the production of dry mixes is relatively simple, although it has its own specific features. Simplified, it can be reduced to drying and fractionation of aggregates (sands), drying and grinding of mineral fillers (if they are not supplied to the plant ready-made), storage (storage) of all components (including binders and additives) and dosing them into the mixer.

A mixing apparatus (the main unit of the technological cycle) is a periodically operating dry mixer capable of homogenizing powders from initial components that differ from each other in particle size (from fractions of a micron to 5 mm) and density (from 0.5 g / cm3 to 4, 0 g / cm3). The final cycle of the technological process is packaging and shipment of finished products (mainly in paper bags).

Technological processes carried out in the production of dry mixes:

Powder storage, dosing, drying, screening, grinding, aspiration, pneumatic transport, packaging. Shipment - similar to the processes used in the production of cement and other binders.

The stationary dry mix plant (ZSS) is designed for automatic production of a wide range of dry mixes: modified adhesive mixes, fugues, waterproofing compounds, plaster mixes, self-leveling floor compounds, primers, protective and finishing compounds, etc.

The dry mix plant includes:

Sand preparation block with drying unit and vibrating sieve for fractionation;

Silos for binders, equipped with aspiration with vibration filters;

Dispensers for inert, binders, pigments and additives;

Twin-shaft mixer with activators;

Bag fillers for packaging ready-made mixtures in bags of 25 and 1000 kg.

ZSS is equipped with a computer control system based on industrial Micro-PC (Octagon Systems). The control and management of the system is carried out by one operator from the operator's room.

Devices for mixing dry building mixtures.

During the mixing of dry building components, the particles are subjected to differently directed forces, and the movement of the particles is the net effect of the addition of these forces. In addition, the mixing mechanism depends on the design of the mixer and the method of carrying out the process, which causes additional difficulties in the mathematical description and modeling of this phenomenon. Nevertheless, attempts are known to qualitatively describe mixing, both by domestic and foreign researchers.

In our opinion, this issue is most fully considered by American scientists, who distinguish five main sub-processes in the mixing process:

Formation of a layer of planes sliding over each other in the mass - shearing mixing;

Moving groups of particles from one position to another - convective mixing;

Change of position by single (separate) particles of the layer - diffusion mixing;

Scattering of single particles under the influence of their collisions or impacts against the mixer walls - impact mixing;

Deformation and rubbing of a portion of the layer - grinding.

Currently, both horizontal (the rotation axis coincides with the longitudinal axis of the apparatus) and inclined drum mixers are produced. In cases where there is a tendency for caking (clumping), a good mixing result is obtained in drum mixers with a ribbed inner surface, since along with pouring the material in such an apparatus is cut off by ribs, which leads to the destruction of the agglomerate. Mixers of this type work most efficiently with large drum volumes (on the order of several m).

Drum mixers of various capacities also have very different power requirements. So, for example, with the volume of the working space of the drum equal to approximately 1.5 m3, the power consumption is 3.8 kW, and with 20 m3 it is 34 kW. This parameter is, however, not decisive when choosing the type of mixer, if the apparatus meets other requirements.

Only in cases where several types of mixers meet all the requirements of the mixing technology, taking into account operating costs and productivity, one or more mixers of lower power are selected.

Calculation of the main technological and transport equipment.

This section provides calculations of the productivity of machines or installations and their number required to fulfill the production program for this redistribution. In this case, one should also take into account the quality characteristics of the raw materials and the requirements for the final product after processing the raw materials on this unit or machine.

When calculating and choosing types of equipment, you should mainly focus on domestically produced machines, mass-produced by our industry.

Usually in course projects on the discipline "Binder" you have to calculate machines for crushing and fine grinding (grinding), drying plants, dust collection systems, supply bins. Therefore, below are recommendations for technological calculations of this equipment.

Calculation of supply bins.

Bunkers - self-unloading containers for receiving and storing bulk materials - are installed above the technological equipment to ensure its continuous operation. Typically, bunkers are designed for 1.5-2 hours stock of material.

The shape and dimensions of the bins are not standardized and are accepted depending on the physical properties of the stored materials, the required stock, methods of loading and unloading, equipment layout, etc. Bunkers of rectangular cross-section have found the greatest application. Typically, the upper part of the bunker has vertical walls, the height of which should not exceed more than 1.5 times the size of the bunker in plan, the lower part of it is made in the form of a truncated pyramid with symmetric or, better, asymmetrical inclined walls. To completely empty the hopper, the angle of inclination of the walls of the pyramidal part should be 10-15 ° higher than the angle of repose of the loaded material at rest and the angle of friction against its walls. The edge of the dihedral angle between the inclined walls should have an angle of inclination to the horizon of at least 45 °, and when storing wet material with a high content of small fractions - at least 50 °. The dimensions of the hopper outlet should be 4-5 times the maximum size of the pieces of stored material and be at least 800 mm.

4. Test methods for dry building mixtures.

Dry building mixtures are tested on the basis of GOST 31376-2008 “Dry building mixtures on gypsum binder. Test methods ".

GOST applies to dry building mixtures made on gypsum binder and used for interior work during construction, reconstruction and repair of buildings and structures.

The standard establishes test means and methods for determining the following quality indicators:

Dry mixtures: humidity; grain composition;

Ready-to-use mixtures (mortar mixtures): mobility; the beginning of setting; water retention capacity;

Hardened mixtures: adhesion to the substrate (adhesion); bending tensile strength; compressive strength.

For mixtures in a dry state, the bulk density is additionally determined, for hardened mixtures - the average density. The methods for determining the bulk density and average density should be specified in the standard for the specific mixture.

Tests of mixtures on a gypsum binder are carried out at an air temperature of 20 ° C and a relative humidity of 60%.

Devices and test equipment used during testing must be made of waterproof materials that do not react with calcium sulfate (glass, stainless steel, plastic, etc.), and must not have any damage or traces of a hardened solution.

The used measuring instruments must be verified (calibrated), and the testing equipment - certified in accordance with GOST 24555, and comply with the requirements of this standard.

A new sample of the mixture should be used for each test.

The test results of mixtures are recorded in a log, which indicates:

The name of the manufacturer of the dry mix;

Conventional designation of a mixture in accordance with a standard or technical specifications for a mixture of a specific type;

The name of the quality indicator being determined;

Test date;

Sampling location;

Results of particular determinations of each indicator and arithmetic mean values \u200b\u200bof test results. To control the quality of dry mixtures packed in bags or bags, take one spot sample from each packaging unit that falls into the sample. The sample size should be specified in the standard or specification for the specific mixture. Spot samples are taken from the middle of each bag or bag using a sampler.

When packing dry mixtures into bags with a capacity of 1 ton (big bags), spot samples are taken from the top layer, the middle and the bottom layer of each bag.

Spot samples on the processing line are taken in accordance with the technological documentation of the manufacturer of the dry mixture.

The total mass of the selected point samples should ensure that a combined sample is obtained, sufficient for at least two determinations of each standardized and controlled indicator of the mixture quality.

Collected point samples are combined and thoroughly mixed manually or mechanically to obtain a combined sample. Mixing mixtures of different lots is not allowed.

The combined sample must be stored in a closed sealed container until it is wetted.

Before testing, reduce the combined sample by quartering or using a powder divider.

For quartering, the combined sample (after mixing) is leveled and divided into four parts by mutually perpendicular lines passing through the center. Any two opposite quarters are connected and mixed. By successive quartering, the sample is reduced by two, four times, etc. until a homogeneous laboratory sample is obtained.

The mass of the laboratory sample must be sufficient to determine all controlled parameters of the mixture quality. The laboratory sample should be stored in a closed, sealed container that prevents moisture.

Weighs are taken from the laboratory sample to determine one indicator in accordance with the test procedure.

Additionally, the mixtures are subjected to the following tests at OOO Kazan Plant of Dry Building Mixes:

Determination of the consistency of the cement slurry;

Determination of the density of the mortar mixture;

Determination of the delamination of the mortar mixture;

Determination of the water-holding capacity of the mortar mixture.

Samples-beams with dimensions of 4x4x16 cm are formed using vibration on a laboratory vibrating table. The vibration time in all cases is 15 s. The molded samples are stored in the hardening chamber until they are removed from the form. After 1 day, the samples are unfolded and placed back in the chamber.

Conditions in the chamber: temperature 20 ± 2C, relative humidity 90%.

28 days after preparation, the samples are tested for bending and compression. To determine the adhesion force of the adhesive compositions to the surface, tile samples are made with dimensions of 7x7x1 cm. The samples are molded and stored until testing in the same way as beams, and then they are glued into a peel test device using epoxy glue.

Samples of masonry mortars and plaster mixes for outdoor use are tested for frost resistance by the dilatometric method.

5. Field of application of dry building mixtures.

The German company Knauf (Knauf) specializes in the production of building materials for external and internal decoration, heat and sound insulation materials.

A very rich assortment of dry mixes: plasters, putties, adhesive mixes, self-leveling floors and decorative plasters and much more.

KNAUF Rotband - gypsum plaster KNAUF Goldband - gypsum plaster "Knauf Rotband" and "Knauf Goldband" dry plaster mix based on gypsum binder. It is intended for manual plastering of walls with a rough surface (plaster, brickwork, foam concrete, etc.) indoors with normal humidity, including kitchens and bathrooms in residential premises.

KNAUF Perlfix - assembly glue "Knauf Perlfix", a mixture based on gypsum, intended for gluing gypsum plasterboard sheets, panels, insulating material (mineral wool, expanded polystyrene) to load-bearing walls during their facing. Used for interior work.

KNAUF LM 21 - heat-insulating masonry mix "Knauf LM 21" dry mix based on cement, lightweight aggregate and polymer additives. for outdoor and indoor work. It is used for masonry and brickwork with increased thermal insulation properties based on lightweight hollow and solid ceramic and concrete stones and bricks, concrete blocks on porous aggregates, foam concrete and aerated concrete.

Knauf Goldband is a dry plaster mix based on a gypsum binder with polymer additives. Designed for high-quality hand plastering of walls with a hard and durable base (brickwork, cement plaster, dense and porous concrete), as well as surfaces made of expanded polystyrene and particle board in rooms with normal humidity, including kitchens and bathrooms.

KNAUF-HP Start is a dry plaster mixture based on a gypsum binder with polymer additives. Designed for manual application on any substrates with a layer thickness of 10 mm to 30 mm in one layer indoors.

Knauf Perlfix is \u200b\u200ba dry assembly mixture based on gypsum binder with special additives. Designed for gluing gypsum plasterboard (GKL), gypsum combined panels (GKP), insulating materials (expanded polystyrene and mineral wool slabs) on brick, concrete, plastered, porous concrete wall bases with an uneven surface. For indoor use only.

KNAUF Fugen is a dry putty mixture for interior work based on a gypsum binder.

Intended for:

Sealing the joints of gypsum plasterboard sheets (GKL) with a thinned and semicircular thinned edge, using a reinforcing tape;

Bonding plasterboard sheets to a flat surface;

Thin-layer puttying of flat concrete and plastered surfaces;

Filling the joints of precast concrete elements;

Sealing cracks and other possible damage to the gypsum board;

Bonding and filling of gypsum elements.

Knauf-Boden 15 is a dry mix based on high-strength gypsum binder, quartz sand as filler and special additives. It is used indoors with dry and normal humidity conditions for arranging a leveling layer 2-15 mm thick on gypsum and cement substrates. Cement substrates may only be leveled after they are completely dry. It is especially recommended for filling prefabricated floor elements KNAUF-Superpol and plaster-based self-leveling screeds. Knauf-Boden 15 serves as the basis for conventional floor coverings. It is applied by hand or using plastering machines, for example, from PFT, equipped with a screw pair R7-1.5 or R8-1.5, a flow meter for 2500 l / h, a 35 mm mortar hose and a Rotomix-R or Rotoquirl-R stirrer. With a small thickness of the applied layer, it is possible to use a screw pair D6-3 with a Rotomix-D stirrer.

Conclusion

Currently, the domestic market of dry mixes is one of the most dynamically developing segments of the building materials industry. The growth rates of the production of dry building mixtures do not fall below 40-50% per year. It should be noted that in the structure of the price of dry mixes, the cost of raw materials ranges from 30-40%. In this regard, it is relevant to use local materials that reduce the cost of dry mixes.

One of the most important problems of the building materials industry is the development of domestic production of effective building materials based on harmonious and balanced activities in relation to the environment, saving material and fuel and energy resources, maximizing the use of local and technogenic raw materials.

In this aspect, building materials and products based on gypsum binders (GW) are promising. Gypsum binders and materials based on them have a number of valuable qualities. The production of gypsum binders is non-toxic, characterized by low specific consumption of fuel and energy (approximately 4-5 times less compared to cement production). Gypsum materials have good heat and sound insulation properties, fire and fire safety, relatively low density, decorative properties.

In addition, the use of gypsum materials for interior decoration provides a favorable indoor climate due to the ability of the material to "breathe", easily absorb and release moisture. Research into the development of waterproof gypsum binders has broadened their potential applications. A new generation of binders based on gypsum binders, characterized by reduced water demand and high operational properties, have been developed.

Knauf dry building mixtures are designed for both outdoor and indoor use. They have good heat and sound insulation, are lightweight and do not shrink.

In Europe, KNAUF cement-based dry building mixtures have been successfully used for more than 30 years, and now the Russian consumer has the opportunity to purchase high-quality KNAUF cement mixtures at affordable prices.

Today the plant for the production of dry building mixtures KNAUF in Kazan is the most modern plant in Europe. The mixtures are produced according to a time-tested recipe and have original German names. Cement-based KNAUF dry mixes are an excellent addition to complete Knauf systems.

The main advantages of KNAUF building mixtures

High adhesive strength of the mixture with the base;

High water-holding capacity of the mixture, which makes it possible to apply the mortar on porous substrates and uniform hardening of the plaster layer;

The mortar prepared from Knauf plaster mixes does not stratify and has high plasticity;

Knauf building mixtures have high crack resistance and frost resistance.

Knauf dry building mixtures, depending on the field of application, can be divided into the following types:

Plastering;

Putty;

Adhesive;

Waterproofing.

Dry plaster mixes make up the bulk of those produced and sold in Russia. The largest volume of production at the Knauf enterprises, especially in Russia, is made up of plaster mixes for hand plastering Rotband and Goldband, made on the basis of a gypsum binder. These mixtures are used only for interior decoration. Possessing higher adhesion, "Rotband" is used for plastering walls and ceilings, and "Goldband" - only walls. The technology of application and the quality of the resulting surface are the same for these mixtures.

Gypsum plaster solutions have a low density: 2 times lower than that of cement-sand mortars. This is due to the use of pearlite sand as a filler in gypsum mixtures. Therefore, it is much easier to work with such mortar mixtures, and the consumption of dry mixture per 1 m2 of surface with a plaster layer thickness of 10 mm is on average 10 kg versus 20 kg of cement-sand mixture. Due to the high water demand of gypsum plaster mixes, the hardened mortars have high capillary porosity, which provides them with fairly high vapor and gas permeability. This creates a comfortable environment for people who live or work in such premises by stabilizing humidity.

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