5. Dry extracts. Extraction methods. Cleaning, standardization, storage. Licorice dry extract technology.

Dry extracts are obtained by distilling off the extractant and (if necessary) subsequent drying of the condensed extract. Most dry extracts serve as intermediates for the production of various dosage forms and combined preparations. Extracts should be packaged in a hermetically sealed container, because many of them are hygroscopic.

To obtain dry extracts, it is possible to use various solvents, taking into account the specific properties of the extracted substance (the solvent is removed from the finished product). Most often, purified water, boiling water, and aqueous-alcoholic solutions are used. If the extraction process is carried out with water in a battery of extracts, a preservative (0.5% chloroform) is added to the extractant.

Extraction is carried out by the following methods

Step (fractional) maceration with periodic stirring

Percolation

Countercurrent batch extraction in a battery of percolators (obtaining a concentrated extract)

Circulating extraction with distillation of volatile extractant (at Soxhlet plant)

Countercurrent continuous extraction

To obtain shelf-stable extracts and eliminate their side effects, ballast substances are often removed from the finished product.

dry extracts are prepared in a ratio of 1: 0.2, i.e. from 1 part of raw materials by weight, I get 0.2 mass parts of a thick extract.

The technology of thick extracts uses purification methods

Deposition of the hood at a temperature not higher than 10 ° С

Heat treatment (boiling)

Alcohol purification

Replacing the solvent (alcohol for water)

The resulting precipitates are filtered off. In addition to the deposition of ballast substances, the methods of adsorption and extraction of liquid liquid can be used.

Depending on the equipment in the production of dry extracts, it is possible to carry out extraction drying, bypassing the evaporation stage and without subsequent grinding of the obtained dry extract (technology of dry extract of licorice root).

Technology for obtaining dry extract of licorice root (from methods)

1 Preparation of medicinal raw materials

2 Preparation of the extractant

3 Extraction of plant raw materials

4 Clean the extraction

5 Evaporation of the extract

7. Grinding the dried product

8. Adding thinner

9. Packing

10. Packaging

The extract obtained by maceration is boiled for 10 min, defended for 0.5 h at room temperature, 0.5 h in a refrigerator and filtered. The filtrate is evaporated to a thick consistency, then dried.

6. Ion exchange method for isolation and purification of alkaloids. Theoretical foundations of technology. Hardware circuit

The extraction of alkaloids from plant materials during ion-exchange purification is carried out with water or a dilute solution of a strong acid (hydrochloric acid, sulfuric acid). The choice of the extractant depends on the basicity of the alkaloids and the nature of the organic acids, in the form of salts of which the alkaloids are contained in the plant material. Salts of weak bases and acids in water undergo hydrolysis, bases of alkaloids are poorly soluble in water. The use of solutions of the listed acids promotes the formation of less hydrolyzable salts, an excess of hydrogen ions promotes a shift in the hydrolysis reaction towards salt formation. The ion exchange of alkaloids is optimally carried out in an aqueous medium, since alkaloids in the form of salts have a high degree of ionization.

Basic principles of adsorption ion exchange technology of alkaloids:

The choice of the ion exchanger and the adsorption conditions should ensure the preferential and maximum adsorption of the recovered alkaloid salt and its minimum residual concentration in the solution under equilibrium conditions.

The desorbing solvent should be selected so that, under equilibrium conditions, the eluate with a relatively high concentration of the substance is in equilibrium with the adsorbent with a small amount of substance, so that the adsorption of alkaloids from the stripping solvent is minimal.

The choice of the optimal pH value of the solution is important. This indicator should ensure the maximum ionization of alkaloid salts in solution and at the same time prevent a decrease in the sorption value of the alkaloid ion due to the competing action of hydrogen ions with an increase in the concentration of the latter.

For desorption of alkaloids from the ion exchanger, it is necessary that there is an excess amount of displacing ion in the solution. Usually, non-aqueous solutions of the displacing component are used. In non-aqueous solvents, the degree of ionization of alkaloids' bases decreases, i.e. conditions are created for the most efficient desorption of organic ions by inorganic ones. The disadvantages of aqueous solutions of alkalis are as follows.

Less yield of alkaloids, since they are partially ionized and undergo reverse sorption.

Alkaloids in an aqueous medium can undergo decomposition, and the loss of alkaloids is also possible, since they are poorly soluble in water and their suspension in water will form during desorption.

During desorption, a lot of ballast substances pass into the eluate. To isolate alkaloids, it is necessary to use strongly acidic ion exchangers, since alkaloids are better absorbed on them and ballast substances are less absorbed. Strongly acidic include cation exchangers containing strongly dissociated acid groups (sulfonic acid, phosphoric acid), capable of exchanging cations of ionic groups for other cations in alkaline, neutral and acidic media. Weakly acidic - cation exchangers containing weakly dissociated acid groups (carboxyl, phenolic, etc.), capable of exchanging their hydrogen ion to a significant extent for other cations only in an alkaline medium.

Characteristics of ion exchangers

Ion exchanger is a complex insoluble polyvalent framework (ion), ionically bonded to mobile ions of the opposite sign. In cation exchangers, the high-molecular framework is a colossal fixed polyvalent anion, the charges of which are balanced by mobile cations, which are capable of exchanging with external cations in contact with electrolyte solutions. Ionites are solid porous substances.

Requirements

Ion exchangers must dissolve in water

Must be mechanically capable, their swelling capacity must be 10-15% of their own weight

Ion exchangers must be chemically resistant, i.e. do not react with secreted substances.

They must have a sufficient exchange capacity, possess selectivity of sorption to the released compounds. The exchange capacity of the ion exchanger is expressed as mg * eq / g of dry resin.

The total volumetric capacity of the ion exchanger (constant value) is determined by the number of ionogenic groups that make up the ion exchanger, that is, it corresponds to the state of limiting saturation of all active groups capable of ion exchange with the exchanged ions. Under dynamic conditions, the total dynamic capacity of the ion exchanger is determined by passing a calcium chloride solution.

The equilibrium volumetric capacity of the ion exchanger (variable value) depends on the factors that determine the state of equilibrium in the solution-ion system (pH, concentrate, t)

In the process of ion-exchange sorption, it seeks to create such conditions that the equilibrium volumetric capacity is as close as possible to the total exchange capacity of the ion exchanger for the released substance.

The efficiency of the sorption process by the ion exchanger is characterized by the value of the selectivity coefficient

Kizb = up / up

Where Kizb is the selectivity coefficient, up is the concentration of alkaloids in the ion exchanger / in the mother liquor after passing through the column, up is the concentration of hydrogen ions on the ion exchanger / in the mother liquor.

The more Kisb> 1, the greater the selectivity of the absorption of the alkaloids cation from the solution.

Packages of sour cream and similar dairy products in plastic containers can be arranged in various ways: using shrink wrap, paper wrapped labels, inmold technology, including can printing. In this case, it can be problematic to use a design that is complex from the point of view of the image, since the low print resolution and the use of only Panton inks impose certain restrictions. The printing technology is dry offset, the number of colors is up to 8 pcs, while the range of the reproducible raster is from 7% to 100%, that is, it is impossible to obtain a smooth transition to the color of the material. The second significant limitation is the line thickness of at least 1 point, and the highly desirable use of a sans-serif font is added to everything, that is, Pragmatics and similar typefaces will do.

Dry offset technology was developed in early 1982 by the Japanese firm Toray Industries. This technology does not require moistening of blank elements and the presence of a dampening device, in contrast to the traditional process of offset printing with dampening solution. Silicone is used to create a layer of ink-repelling white space on the plate. The absence of a dampening solution has both positive and negative sides: the absence has a beneficial effect on the printing process, since there is no problem of ink emulsification and the associated distortion of gradations, there is no need to constantly maintain the ink-water balance, and the main difficulty is the creation of paints, which which have special requirements, because they should not be perceived by blank areas of the form. The peculiarity of dry offset printing is that the printing process must take place while maintaining a certain temperature level (since the viscosity of the ink depends on the temperature). A decrease in temperature leads to an increase in viscosity and to a deterioration in the transfer of ink to a form, and therefore to prints. An increase in temperature leads to a decrease in viscosity, which can lead to shadowing of forms and prints.
For printing using dry offset technology, UV inks are also used, which allow applying thicker ink layers than conventional offset ones.
The advantages of dry offset include a higher print quality compared to traditional offset, namely, increased clarity, contrast and saturation of prints, better development of highlights and shadows, as well as a reduction in production time for print preparation and reduction of production costs associated with maintaining a complex dampening apparatus. , increasing the stability of the printing process and improving its environmental performance, since there is no need to use isopropyl alcohol.
The disadvantages of dry offset include, first of all, the higher, in comparison with the traditional offset, the cost of printed products due to the high level of prices for consumables and a narrower range of specialized printing inks, in particular metallized.

It is optimal to prepare a design for such a process in the form of a finite number of vector objects, it is convenient to manage them both at the development stage and at the stage of preparation and adjustment to the required size, in addition, in most cases, such elements are fairly well scaled to different can sizes, if it is supposed some serial production. It should be remembered that a sufficiently low ruling does not allow high-quality reproduction of smooth gradient fills and the raster will be clearly visible. About the design for this type of printing, it is good to use the rule: do not be small, all elements must be drawn large enough with clear edges.
This raises the question of preparing photographic design when using halftone images formed by more than one color for each design element. For example, a landscape: a blue sky with clouds, green grass and colorful flowers, and, for example, a bicycle. In this case, especially if you need to replicate the design on several media of different format - 150, 250, 400 g cans - you can make each element described above as a separate PSD file with a clear clipping path, obtained either using the Path tool, or with the maximum contrast h / b mask, and compose it in the assembly program, most often in Illustrator, coloring the inserted halftone images - essentially applications - in the necessary selected pantones. For green grass fields, it may be necessary to use more than one paint - almost 100% yellow solid and a raster from some light blue, in principle, it is possible to use process colors.
This technology is somewhat reminiscent of preparing designs for printing on aluminum cans, where the paint is also applied directly to the material.
From the point of view of the cost of production and its quality, it cannot be said that this is exclusively the prerogative of the regional market, some design is much more convenient to print this way, and the absence of additional packaging components such as films and cardboard can be beneficial in terms of disposal of empty containers, including recycling ...

The uncomplicated technology of dry screed for leveling the floor allows you to cheaply and quickly prepare it for the installation of the finishing decorative coating. Its principle has been known for a long time, and improved materials make it even easier to implement.

Attracts dry concrete screed with low weight and versatility. It increases the mass of the structure to be erected to a minimum, is relatively inexpensive, besides, it will help to save money that you can work with it independently without spending money on hired labor.

• Why dry?
• Pros and cons of dry screed
• Materials and tools for dry floor screed
  • Consumption of materials for dry screed
• Surface preparation
• Dry screed laying technology
  • Exposing lighthouses
  • Backfill of expanded clay
  • Laying sheet material
• Screed cost and material consumption

Why dry?

For many decades, traditional types of cement screeds have been successfully used in practice. The classic components for such screeds were necessarily:

• cement;
• sand;
• water.

Only their ratio and the quality of individual components changed. But experts from the German company Knauf took up the implementation of a new project suitable for leveling the floor - it was they who came up with the joint use of materials such as dry screed and gypsum fiber boards (gypsum fiber sheets). The technology turned out to be so simple that it became available to everyone. Here, in addition to GVL, expanded clay will be required as the basis of the screed.

First, a loose material is poured onto the rough floor - expanded clay, which is sprinkled with sand or perlite, and then tile materials are laid on top: gypsum fiber board, fiberboard, chipboard or plywood. The modules of the upper bonding layer are fastened with self-tapping screws and glued.

Pros and cons of dry screed

A dry floor screed is quick and easy to install. But in addition to these two advantages, it has a number of others:

• Materials for dry floor screed cost several times less than for concrete, which is always a significant plus.
• Greater cleanliness of work - since the cement-sand mixture does not mix with water, dirty streaks and puddles do not appear.
• Bulk insulation is most often used as a pillow for a dry screed, which guarantees good thermal insulation of the floor.
• The design is much lighter than with a traditional cement screed, because the leveling material and expanded clay weigh much lighter, in addition, their use reduces the consumption of dry mix for the screed, which means that the load on the floor is also reduced. Therefore, this system is advantageous when renovating floors in old wooden houses.
• The fill layer can also be used for laying various communications or, for example, a warm electric floor in the form of mats or cables. After arranging the dry screed, you can immediately start laying the topcoat, while after laying the "wet" cement screed, you will have to wait a very long time until the concrete is completely dry.

As you can see, there are many advantages here, and if you list what disadvantages a dry screed has, then perhaps one, but very significant and unusual, will be remembered - the fear of water ingress. One has only to get a small amount of water on the surface of plywood, gypsum fiber board or chipboard, as they swell with bubbles and warp.

Materials and tools for dry floor screed

In order to perform a dry screed, a knowledgeable master will surely invite an assistant. No matter how light the materials are, you will have to drag a lot of them, and besides, it is more convenient to stack large sheets together.

So, here are the materials you need:

• GVL with dimensions 60x120 cm. This format of sheets has been specially reduced so that even one worker can handle them when laying. These are two sheets glued to each other with some offset, which are also called "dry floor elements".
• Small fraction expanded clay. A dry mix for floor screed can be not only expanded clay, but also a fine-grained fraction of slag, perlite and even crumbs from expanded polystyrene plates.
• Polyethylene film as a waterproofing, which is laid on the base before backfilling expanded clay.
• Self-tapping screws for fixing GVL.
• PVA glue.
• Edging tape.

And also tools for work:

• roulette;
• pencil;
• jigsaw or knife with which you can cut GVL;
• screwdriver;
• narrow spatula;
• rule;
• metal profile PN-27/28 (it will serve as beacons).

As an additional tool, you may need a paint brush, which will come in handy when, before applying glue at the joints of the slabs, you need to wipe off expanded clay crumbs from them.

Consumption of materials for dry screed

First of all, you need to take care of the required amount of materials, because when a dry screed is made, their consumption can be significant, so it is important to correctly calculate their amount:

• The volume of expanded clay is determined by the layer thickness and the total backfill area. At least 3 centimeters of expanded clay can be filled in, however, the thicker the layer, the better the floor will be thermally insulated. On the other hand, we must not forget that the higher the floor rises, the closer the ceiling will be to it, that is, the room will become lower.
• It is cheapest to use ordinary polyethylene film as waterproofing, the thickness of which is not less than 0.2 mm. Its amount should exceed the area of ​​the room, since part of it will go for overlaps and allowances on the walls.
• The number of guide metal profiles will also depend on the size of the floor.
• The length of the damper tape, which is laid along the perimeter of the walls, is determined by this perimeter.
• Slab leveling materials should also, in aggregate, have an area equal to the area of ​​the room, but with some margin.

Surface preparation

1. If the repair takes place in the apartment, then before making a dry screed, you need to remove the old floor covering and all the layers under it until a reinforced concrete floor appears.

1. The surface of the slab must be inspected and all defects found on it (grooves, cracks, chips) must be repaired, using a ready-made plaster mixture or cement-sand mortar for this purpose.

1. The repaired places need to be allowed to dry, after which the repaired sub floor should be thoroughly swept out of dust and dirt, so that then we can put the waterproofing material on it - polyethylene. The film must completely cover the floor surface and "climb" on the walls along the entire perimeter to a height that is determined by the thickness of the dry screed.

1. The film is usually laid in the form of several parallel stripes, which should overlap each other by 10-15 cm. To make the waterproofing airtight, the edges of the strips must be glued together with construction tape.

The question may arise: if the screed technology is completely dry, then why do we need waterproofing? The thing is that the floor slabs are not monolithic, they have gaps that let moisture through, albeit slowly, from the lower floor or from the subfloor (if we are talking about the first floor). Therefore, only high-quality waterproofing can stop the flow of moisture. These precautions are also justified by the fact that the dry screed does not like water ingress.

1. Then, along the perimeter of the walls, you need to place a damper tape. This tape is made of foamed PVC, one side of which is self-adhesive, protected by a polyethylene film. The protective film must be removed and the tape must be immediately glued to the wall surface. The purpose of the damper tape is to compensate for the thermal expansion of the dry screed. In addition, it will prevent the leveling sheets from contacting the walls, which will protect them from deformation, and the residents from an unpleasant squeak.

1. After installing the edge strip around the perimeter of the walls, the entire vapor barrier structure at the base of the floor is considered complete.

Dry screed laying technology

If a dry floor screed is chosen, its technology consists of several successive stages. These stages will be listed below with reference to the fact that expanded clay will serve as a bedding.

The process of installing a dry screed begins with attaching the beacons as guiding elements. It is with their help that the dry screed - expanded clay is leveled in height, they determine the thickness of the bulk layer. Some seasoned craftsmen manage to do without beacons, but beginners are strongly encouraged to use them.

Exposing lighthouses

Most often, special T-shaped lighthouse profiles are used for dry screed, which are attached with self-tapping screws to the base of the floor, but before that they need to be exposed using certain tools, which include:

• rule;
• laser level;
• pencil.

Sequence of work:

1. The laser level must be installed in the center of the room and switched on.
2. After that, half a meter from one of the corners of the room, a self-tapping screw should be screwed into the floor, a rule should be installed vertically on it and a trace of the laser beam should be marked on it with a pencil.
3. After that, along the diagonal of the room, closer to the other corner, also screw another self-tapping screw into the floor, put a rule on it and check the coincidence of the line drawn on it with the laser beam.
4. If they diverge, then the self-tapping screw should either be screwed in even deeper, or unscrewed a little, ensuring that the mark exactly coincides with the laser marker.
5. Carry out similar actions with all intermediate self-tapping screws, or it is easier to do: pull a thin and strong thread between the extreme fasteners, and, focusing on its level, screw the self-tapping screws into the floor after 20 cm.
6. Then you can check the work - put a flat rail on the screws, and a regular water level on it. If everything is done correctly, the level will confirm the horizontal position of the rail.

1. After that, the lighthouse must be fixed with cement or plaster mortar.
2. The guide element on both sides of the self-tapping screws should be overlaid with mortar and allowed to dry.
3. Do the same with all other lighthouses.

Backfill of expanded clay

If not a dry screed with sand is done, but with expanded clay granules, then they should be as small as possible. After all, sheets of leveling material will rest on them, which in the case of large granules will have a point, chaotically located support and from this will deform, and dips will appear.

1. Expanded clay for a dry floor screed should not be poured onto the entire floor at once, but only its area.

1. Having reached the level of the beacons in this place, you should immediately put a tile leveling material on top, for example, gypsum fiber board.
2. The legs of a working person should be on a clean floor, free of expanded clay.
3. After that, you can proceed to backfilling the next section and laying the next slab on it.

But a number of craftsmen also have an alternative approach - they first cover the entire floor with expanded clay, level it with the rule according to the level of beacons, and then move along the floor, placing pieces of gypsum fiber board or plywood under them.

Laying sheet material

There are a number of points that require special attention:

1. If gypsum-fiber sheets are used for alignment, then it is advisable to lay them in two layers, which must be fastened with self-tapping screws, and then the joints should be coated with glue. Considering this feature, Knauf began to produce ready-made double sheets with a folded joint - "Knauf superfloor". It makes it easy to create beautiful flooring that meets all modern requirements.
2. In the case of using plywood or chipboard, they can be laid in one layer, but only if their thickness is at least 12 mm. These materials must also be treated with protective agents - bituminous mastic or hot drying oil.
3. When stacking, sheets must be pressed tightly against each other. If the gaps still work out, then they should be filled with a putty solution.

If the expanded clay is backfilled in sections, then installation should be started from the corner farthest from the entrance door of the room. If the floor is completely covered with expanded clay beforehand, then the installation, on the contrary, should be started from the front door, so that you can easily move along the previously laid slabs.

1. In the case of using the "super-floor Knauf", the folds of the slabs must be coated with glue and connected with special self-tapping screws with a length of 19 mm. These self-tapping screws have countersink heads, thanks to which the fasteners are deeply recessed into the GVL. This helps to get rid of unnecessary height differences during the installation process.

1. When all the installation work is completed, then all the protruding edges of the damper tape and plastic film must be cut off, and the resulting gap between the walls and the dry screed must be filled with sealant.

Screed cost and material consumption

Calculation of a dry screed is quite easy to do. So, for a room with an area of ​​100 m2, approximately 150 m2 of waterproofing, 100 m of a profile, 5 kg of glue and 1200 self-tapping screws will be required.

The consumption of the dry mix for the screed here will depend on the thickness of the screed: if the average thickness of the backfill is about 3 centimeters, then 4 m3 of bulk material will be required to accommodate such an area.

Well, the answer to the question of how much a dry screed costs is made up of the cost of all the materials necessary for work.

Would you make a dry floor screed in your apartment or house? Or do you already have experience with it? How did you like it, and what shortcomings did you note? Let us know in the comments.

Updated: 02.09.

To paraphrase a well-known saying, then during a major overhaul or construction of a house “the floor is the head”. The condition of the entire internal interior largely depends on how high-quality, sealed and even the floor in your living quarters will be. One of the ways to create a perfectly flat supporting surface in an apartment is to use a dry do-it-yourself floor screed.

Arrangement of the floor screed is necessary to create an even and solid base for the finishing floor covering. At the same time, almost any type of coating can be placed on the screed - both laminate and linoleum. The construction of the screed is necessary even before laying the tiles, otherwise you will need a lot of glue to level the surface.

Floor leveling technology can be divided into two large groups.

• Wet screed Is one of the most common ways. It consists in pouring a cement-sand mixture onto the floor according to previously exposed beacons. This technology is considered dirty and time consuming.
• Dry screed is a relatively recent technology. The production of modern materials has made this process relatively quick and easy. In general terms, this technology consists in backfilling dry granular material onto the rough floor, leveling it and then laying strong sheet material.

This figure shows a schematic diagram of a dry screed floor. Its main elements are:

• rough overlap;
• a layer of waterproofing (usually polyethylene is used);
• a layer of bulk granular material (expanded clay);
• connecting glue (PVA is used for GVL sheets);
• screws for fastening floor elements;
• prefabricated base of the leveled floor (usually GVL sheets);
• a layer of glue for fixing the topcoat;
• finishing floor covering;
• plinth fasteners;
• decorative corner or plinth;
• edge tape.

dry screed

Advantages of using dry screed technology

The following advantages of using dry screed technology for leveling the floor can be noted:

• ease of installation, available for self-repetition;
• the use of dry screed technology allows you to correct mistakes without much labor costs, while it is possible to correct the shortcomings of a "wet screed" only with great difficulty;
• it is simply impossible to remove an incorrectly poured cement-sand mortar without the use of specialized tools, at the same time, you can disassemble and re-form a dry screed on your own using a minimum set of tools for one person;
• dry screed can be built gradually, meter by meter.
• the formed screed from the cement-sand mixture reaches its working state in at least three weeks and only after complete hardening can you start installing the finishing floor covering, and when using the dry screed technology, start laying the laminate or linoleum on the same day;
• a screed formed by dry technology has higher thermal insulation rates, which is caused by the presence of air sections between the granular mixture;
• a high degree of thermal insulation of floors on a dry screed allows them to be used when forming overlappings of rooms located above unheated rooms, when insulating loggias or balconies;
• the dry screed, in addition to thermal insulation, also has excellent sound-insulating properties (in addition to air spaces in the bulk filling, an edge tape made of foamed polyethylene, which is laid along the perimeter of the room and perfectly dampens sound waves, also contributes to an increased level of sound insulation).

Calculation of the cost of a dry screed. Necessary materials

We will calculate the necessary building materials required for arranging a floor with a dry screed in a room with an area of ​​100 m 2.

In order to build a leveled floor for finishing, we need:

• metal profile - about 100 running meters;
• expanded clay - 4 cubic meters;
• leveled floor slabs - GVL sheet with an area of ​​100 m 2, plus about 20% for cutting;
• polyethylene film for moisture insulation (with allowance for walls) - about 150 m 2;
• self-tapping screws - 1200 pieces;
• glue (ordinary building PVA) - 5 kg.

At current prices, the total estimate for the purchase of building materials will be about 45 thousand rubles.

To form the coating, you can use both single sheets of gypsum fiber board and double sheets prepared in advance in production. Such sheets are glued together with a slight offset relative to each other so that a protrusion is formed along the edge to form a lock. The procedure for laying such sheets is similar to laying a laminate.

Before starting leveling the floor using dry screed technology, finish all electrical work, carry out all the necessary engineering communications. The gaps and holes between the sub-floor and the walls can be covered with cement-sand mortar.

Self-leveling technology of the floor using dry screed technology

Leveling the floor using dry screed technology is simple enough to be repeated even by people with minimal technological skills. It is necessary to carry out five operations in sequence.

1. Surface preparation

When carrying out repairs in a house with an old floor covering, first of all, it is necessary to dismantle the old finishing floor covering. In the event that it is placed on a wooden floor and on logs, dismantle them as well. It is especially important to get to the concrete floor slabs in houses built using panel technology, since the quality of their installation left much to be desired. After filling the cracks, clean the floor surface.

1. Laying the waterproofing layer

In order to prevent moisture from penetrating the floor covering, a layer of vapor and moisture insulation is placed under the base of the dry screed on the ceiling. You can use plastic wrap or glassine. To improve insulation, the film layers should overlap each other by about 15 centimeters. The insulating film must go onto the walls at least to the height of the future dry screed.

On concrete floors, you can lay a polyethylene film with a thickness of about 250 microns. If you level a wooden floor with a dry screed, then bitumen-impregnated paper or glassine is used as an insulating layer. Similar materials with various trade names are also commercially available.

The absence of a vapor and moisture barrier can lead to moisture penetration between rooms, which negatively affects the creation of comfortable conditions.

1. Placement of soundproofing along the perimeter of the walls

Sound in living quarters is usually transmitted through solid objects. In order to prevent the spread of extraneous sounds, it is necessary to create a sound-insulating layer along the perimeter of the walls. To create it, a tape made of mineral or glass wool or foamed polyethylene is used. The sound-insulating layer should be about 1 centimeter thick.

The sound insulating layer has another function. It prevents the leveled floor sheets from swelling due to thermal expansion.

1. Laying loose granular material

A homogeneous granular material is used to create a heat-insulating leveling layer. Usually, in this capacity, material of inorganic origin is used - expanded clay or fine-fraction slag. Fine sand can also be used as insulation.

Before filling in the insulation, it is necessary to determine the horizontal upper level of the new floor. For this, a laser level is used, which projects a laser beam onto the walls of the room. The height of the insulating layer is usually at least 3 centimeters from the highest point of the floor.

After marking, they begin to install beacons from a metal profile, which is placed in parallel rows at a distance of a meter from each other. The position of the lighthouses () relative to the floor is regulated with the help of small piles of cement-sand mixture and wooden pegs. You can control the level of the exposed beacons using a thin cord stretched from wall to wall along the verified level marks.

To level the layer of bulk material, the rule is used - a long section of a strong metal profile. It is laid on the lighthouses near the wall and then shifted towards the exit from the room, moving the excess insulation.

If you do not need additional insulation of the floor and smoothing irregularities (for example, in new buildings on an existing screed), then sheets of expanded polystyrene foam can be laid directly on the floor, the waste of which can be added to the bulk material to increase thermal insulation.

expanded polystyrene

1. Laying floor sheets

When the height of the bulk material reaches the upper level of the beacons, you can start laying sheet material. There is a fairly large assortment of products on the market that you can use. Some of them even have an additional polystyrene foam insulation layer.

For laying the sub-floor, you can also use chipboard boards with tongue-and-groove and moisture-resistant gypsum fiber. It is also allowed to use asbestos-cement boards and waterproof plywood.

chipboard plate

Subfloor slabs are stacked end-to-end. Only leave gaps between the boards if the material tends to expand thermally. The specific gap size can be calculated from the sheet specifications. So, if the material can expand by 1 millimeter per 1 running meter, then at least 2 millimeters of the gap must be left between the 2-meter plates.

Subfloor slabs can be laid in one or two layers. In multilayer laying, the sheets are fastened together with glue or self-tapping screws, which must have a countersunk head and, if necessary, their landing sites must be putty.

The technology of forming a flat floor using a "dry screed" is quite accessible for independent repetition. Its undoubted advantage is the ability to quickly "rollback", that is, to correct mistakes. The floor laid according to this technology can withstand the same loads as that formed according to the "wet technology".

You can familiarize yourself with the technology of dry floor screed in more detail in the training video.

To obtain a flat surface, perform a floor screed: dry or wet. Each of the options has its advantages, but there are also many disadvantages. Traditionally, many craftsmen prefer the "wet" method, which involves pouring with a semi-liquid mixture. Its disadvantages include labor intensity, a large amount of dirt, it will take at least 2-3 weeks to dry. The cement layer creates additional stress on the floor.

An excellent alternative to the wet method is the dry method. It allows you to get the perfect foundation with less time and effort. In the future, it can be used for laying parquet, linoleum, carpet, tiles. This technology is gaining in popularity. Performing a dry floor screed with your own hands will not be difficult.

The name "dry floor screed" means that it does not use water. The classic "wet" version involves the use of a semi-liquid mixture of sand, cement and water. Due to the force of gravity, forcing the liquid to be evenly distributed over the volume it occupies, a perfectly flat surface is provided. It would seem that you can think of better? However, specialists managed to create a fundamentally new technology, the implementation of which is available to an ordinary person.

The floor, made on the basis of a dry screed, is a multi-layer structure. The first layer is dry backfill, then gypsum fiber sheets (GVL). Such a dry-pressed floor screed creates excellent sound insulation and retains heat well. Its creation will take no more than 2 days, depending on the amount of work. The only limitation for doing dry floor screed with your own hands is wet rooms. Absorbing moisture from the air, expanded clay or other filler, it loses its shape and swells. As a result, the floor is no longer even, and the finish is deformed.

Manufacturers offer several options for dry mix for floor screed. They differ in the complexity of preparation and purpose. They are chosen taking into account the characteristics of the base:

• Alpha - suitable for flat floors;
• Beta - for a flat base covered with a layer of porous or soundproof material;
• Vega - placed on a leveling, soundproof layer;
• Gamma - intended for laying on a leveling layer of backfill, after laying heat-insulating materials with an interlayer of gypsum plasterboards.

The finished screed is a bit like a puff cake. It can be laid on concrete or even wood. Inside it, you can safely lay communications. It is perfect for installing a warm floor, it has a positive effect on its energy efficiency.

Dry floor screed technology

Before proceeding directly to the work, you will need to prepare materials: waterproofing film, expanded clay, gypsum plasterboard, profiles for beacons. The sheets are fastened with self-tapping screws, additionally fixed with construction glue. The dry floor screed is carried out in stages.

Preparatory stage. The arrangement of the floor begins after the completion of the installation of plumbing, fitting of pipes, power grids, and the completion of other work. Remove old materials before installing new flooring. Then level the base, seal the cracks, protrusions, chips with a cement mixture. When the "dirty" stage is passed, you need to thoroughly sweep the formed debris, collect dust. Mark the height of the screed on the walls.

Stage two - laying the insulation. The dry floor screed technology includes a waterproofing layer made of polyethylene or glassine. Better to use the whole canvas. If the installation is carried out in pieces, they should overlap each other with an overlap of at least 20 cm. On the wall, the film is brought up to the floor mark (at least 6 cm). Insulation is chosen taking into account the characteristics of the overlap:

• concrete - take polyethylene with a thickness of 200-250 microns;
• wood - it is better to use glassine or moisture-proof paper impregnated with bitumen.

The task of the moisture-proof layer is to protect the backfill from swelling when absorbing water or steam.

Performing a dry floor screed with your own hands, you should not forget about soundproofing. It is made of glass wool, polypropylene foam or mineral wool, gluing tape around the perimeter of the walls. Such a strip will protect against extraneous noise, it prevents the floor from deforming during thermal expansion.

Stage three - placing beacons. Without using devices, it is simply impossible to evenly lay the bulk mixture. It is not worth hoping that then it will be possible to level it with a level: each pass along the viscous base leaves traces of the feet. Complex equipment is not needed, U-shaped profiles are enough. They are turned upward with a sharp edge, set in level, and fixed with self-tapping screws. Between them then expanded clay will fall asleep.

The main stage is the arrangement of the floor. First of all, the mixture is poured, trying to create a uniform layer. It is made from expanded clay, fine-grained slag, quartz sand, or a ready-made mixture is obtained. The amount of backfill is determined by the unevenness of the floor. The layer thickness on average reaches 4 cm, it is not recommended to make it more than 6 cm. Sheets are laid on the prepared floor, they are fixed to each other. The sheet should not be pressed into the sand, nor should it be moved. Laying GVL on the backfilled surface begins from the door. If the sheets run on top of the insulating material, they move from the opposite wall to the door.

The sheet material is laid with an offset (like bricks) to provide the floor with strength and stability.

The sheets are fastened with self-tapping screws along the perimeter, placing them every 15-20 cm. Additionally, the canvases can be fixed with glue. Irregularities are sealed with putty, then sanded. The surface of the sheets is covered with bituminous insulation. Now you can start finishing. Although it is better to give the floor 2-3 days to "lie down".

Advantages and disadvantages

The dry floor screed has earned its popularity due to its many inherent advantages. The main one is that it does not need to be dried. After the end of the installation, you do not have to wait 45 days, as is the case with a concrete base. The very next day, you can lay linoleum, lay tiles or lay a parquet board. Another important plus is the low weight of the coating. The additional floor load it creates is minimal. The time that will have to be spent on execution depends only on the area of ​​the premises and the efficiency of the contractor. This layered "cake" improves sound and thermal insulation.

To complete the picture, it is necessary to note the disadvantages of a dry floor screed. There are not many of them, but they are there. This coating is not recommended for unheated rooms, bathrooms, showers. A traditional or semi-dry screed is suitable for them. Having dealt with the pros and cons, you can safely get to work. For residential premises, this option is ideal. Its small shortcomings are more than compensated for by the simplicity and speed of installation. Its implementation is within the power of even one person. Only when laying GVL is it better to use the help of another person, since it is inconvenient to cope with them alone.

How to make a dry floor screed

Starting the repair, each master decides the question: what can be done independently, and what work will require the involvement of specialists? A dry floor screed is quite do-it-yourself. The implementation technology is simple, does not require the use of complex equipment. If you carefully study the order of execution, then there will be no difficulties. Here it is important to adhere to the accepted rules, to use the materials recommended for dry floor screed.

A common mistake of craftsmen is the neglect of the damper tape laying. Its absence will make itself felt immediately after the start of floor operation: squeaks, sounds will not let you enjoy the new renovation. The tape can be glued to PVA, double-sided tape, or fixed directly to the polyethylene with a stapler.

Another important question: what to choose as a backfill? There is no strict requirement - sand, expanded clay or slag. These materials have similar characteristics: they do not burn, keep warm, do not shrink. The thickness of the layer should be at least 3, but not more than 6 cm. If the floor is even, you can do without it at all. Then, instead of backfill, plates of extruded polystyrene foam are used.

When starting the installation of a dry floor screed made of GVL sheets, it is important to avoid direct walking on the backfill. Therefore, the sheets begin to be laid directly from the door. When one sheet is laid, the floor is still "walking" underfoot. There is no need to be upset: each subsequent sheet gives the structure the required stability.

Installation work can be carried out at any time of the year. The main thing is to follow the technology exactly, laying out "layers" of a waterproofing film, a leveling layer, surrounding it with a damper tape, and sheet material as a basis for the topcoat.