Screed with expanded clay refers to the type of unconnected screeds. It consists of two layers: expanded clay backfill and cement-sand fill. The thickness of the screed, as a rule, is 3-4 cm. The thickness of the expanded clay layer can be arbitrary, it depends on the required total thickness of the screed.
What is the role of expanded clay in the screed? Expanded clay is a lightweight and fairly durable material made by firing clay or clay shale. Due to its porous structure, it is a good heat insulator. Considering the properties of expanded clay, it is used in a screed in two cases: when it is necessary to insulate the floor or it is necessary to raise the floor level without overloading the floor of the building.
The device of a screed with expanded clay is carried out in three stages: preparation of the floor and backfilling of expanded clay, installation of beacons and pouring of cement-sand mortar.
Work on creating a screed with expanded clay begins with cleaning the base of the floor and sealing the joints of the floor slabs. Traditionally, the joints are sealed with a cement-sand mortar in a ratio of 1: 3. Then a thick plastic wrap is laid on the floor. The film is laid in such a way that an overlap is formed on the walls higher than the level of the screed. The film plays the role of waterproofing, it is necessary to prevent possible leaks.
Fig. 1.
An important element of the expanded clay screed is the edge band. It fits around the perimeter of the room and is fixed to the wall. Considering that the screed with expanded clay is unbound, i.e. floating, then the edge tape will not allow the cement-sand mixture to stick to the walls. Thus, dangerous stresses in the screed, which can lead to its destruction, will be excluded.
Fig. 2.
The next stage is expanded clay backfilling. Expanded clay for screeds is used for medium and coarse fractions (from 10 to 40 mm). To ensure good heat and sound insulation of the screed, the minimum thickness of the expanded clay layer should be 30-50mm. The backfill layer thickness should be 3-4 cm less than the required floor level. It is easy to determine the required amount of expanded clay; it is enough to know the volume of the required backfill. For the calculation, it is convenient to use the density value of expanded clay, which is 250 kg / m3.
If heavy loads will act on the floor of the room, or the area of the room is large enough, the screed with expanded clay must be reinforced. Metal welded mesh is used to reinforce the screed. The mesh is laid on the floor and raised above the surface of expanded clay by about 1 cm. This is necessary so that after pouring the cement-sand mortar, the mesh is in its lower layer, so the strength of the screed with expanded clay will be greatest.
Fig. 3.
Lighthouses are an essential element of screed technology. It is only thanks to the beacons that it is possible to perform the screed with great precision. A beacon profile or a drywall profile can be used for the screed. When installing a screed with expanded clay, beacons are installed on a cement-sand mortar. The solution is applied along the line of installation of the beacon, the beacon is laid on it and it is leveled.
An important point is the location of the lighthouses in relation to the walls and to each other. The extreme beacons should be 20-30 cm away from the walls. The distance between adjacent beacons should be 5-10 cm less than the length of the rule. Often, for the convenience of pouring the screed, the distance between the beacons is 90 cm.
Fig. 5.
A solution for a screed with expanded clay can be prepared independently or you can buy a ready-made one. Homemade mortar is made from a mixture of sand, cement and water in a ratio of 1: 3: 0.7. To prepare the solution, you need to take one part of the cement, mix it with three parts of dry sand and mix the resulting mixture thoroughly, then add 0.7 parts of water and stir the solution. To facilitate the preparation of the solution, it is convenient to use a large bucket and a mixer. A perforator with a nozzle can serve as a mixer.
The finished solution is poured between the beacons and leveled. To level the mortar, use the rule. Leaning on the lighthouses, the rule is moving towards themselves slightly shaking, so the solution is well compacted and leveled. Thus, the entire floor surface is poured step by step.
After the screed with expanded clay is poured, it is necessary to provide conditions for the hardening of the solution. To do this, it is necessary to close the room and prevent drafts. Otherwise, the screed may crack. The screed hardening process takes about 2 days, after which you can walk on the screed. However, the screed still contains a lot of moisture, which is not acceptable for laying any floor covering. Therefore, it is dried within 25 - 30 days. At this time, it not only gets rid of excess moisture, but also acquires the necessary strength.
Fig. 7.
This completes the creation of a screed with expanded clay. As can be seen from the above, the device of a screed with expanded clay is quite simple, and differs from a traditional screed only by the presence of a base layer of expanded clay. Due to the properties of expanded clay, the screed is light and warm. Therefore, a screed with expanded clay is very popular.
Any transformation of a living space into a new and more comfortable nest cannot do without a perfect floor. The smooth surface not only pleases the eye with its perfection, but also embodies an excellent basis for any floor covering. One of the simplest and most affordable leveling methods for everyone is a floor screed with expanded clay. But is it? Let's take a look at all the intricacies and twists and turns of this traditional and very popular technology.
Basic properties and functions of a floor screed with expanded clay backfill
In addition to the main problem that the expanded clay screed solves - high-quality leveling of any, even problematic base, adding a filler performs the following tasks:
- leveling the level;
- sound insulation increases;
- such screeds provide excellent thermal insulation, which, in turn, reduces the cost of heating the room. Therefore, floor insulation with expanded clay under the screed is not only the easiest, but also the most profitable choice;
- due to the porous structure, expanded clay does not allow the room to overheat in the hot season.
The amorphous filler has a relatively low weight and density. But at the same time, the concrete layer gives good strength. The tandem of such building materials as a result gives rise to an excellent floor base, which not only loads the floor to a minimum, but also does not lose its characteristics during operation.
If we take a closer look at expanded clay and its properties, we can conclude that the porous structure endows the granules not only with heat-saving characteristics, but also with water-repellent properties. In addition, it is inert and possesses rare qualities - compatibility with any building material and ensuring a high level of adhesion.
Do-it-yourself floor screed with expanded clay is relevant in the following cases:
- when the base is represented by reinforced concrete slabs;
- leveling floors under one level, provided that their difference is more than 10 mm;
- if communications are hidden below;
- minimizing the concrete mix;
- if heating is carried out electrically or infrared;
- low noise permeability.
Expanded claythe screed is indispensable for obvious flaws in the base, which can not only appear on the finish coating, but also spoil it.
Types of expanded clay backfill and which one to prefer
Expanded clay is a material obtained in the factory by high-temperature firing of finely dispersed foamed clay. Three types of fractions of expanded clay aggregate for floor screed are produced:
- crushed stone, with coal particles, no more than 40 mm in size;
- gravel - round or oval granules with a fraction of up to 40 mm;
- sand, with a particle size of up to 5 mm.
Depending on the type, expanded clay is used in screeds with different requirements. For a traditional screed, a fractional aggregate is used, since it is subsequently covered with either an even concrete layer or other materials that level the surface. Therefore, the size and shape of the granules are not critical.
It is a misconception that expanded clay sand is most suitable for arranging a base with a minimum weight. But it has a higher density than a related aggregate, as a result of which the weight of the screed itself also increases.
But fine-grained sand is indispensable in cases where backfill with less shrinkage is required, for example, to level the base with a large difference in levels - more than 10 mm. It is also best to use sand for difficult areas with severely damaged surfaces and when installing block parquet flooring.
Types of technologies for installing screed with expanded clay aggregate
The flexible characteristics of the aggregate itself make it possible to use it in different ways, depending on the circumstances and the room itself. There are three main types of screed installation.
Dry method
It is applied when:
- the device of communications at the floor level;
- if you need to make a screed in a short time. After 24 hours, you can not only carry out finishing work, but also lay the topcoat;
- if there is a need to install a screed with a minimum weight;
- if desired, carry out clean work;
- when installing the maximum heat-absorbing floor.
Bulk method
Installation using bulk mixes for various purposes. A screed device with a self-leveling coating is used in cases of total leveling of the base under one level, but subject to a small layer. It is perfectly suited for renovation in apartment buildings.
Typesetting technology
Traditional concrete screeds on expanded clay are used to insulate and level the base. This method can be distinguished among the main ones by a relatively low cost and a large leveling layer, which is ideal for heavily damaged bases.
In any case, by whatever method the floor is pulled out, the technology of other plastering work must be carried out in advance.
Dry screed
Consider in detail the dry method of installing a floor screed with expanded clay. In addition to the filler itself, sheets of GVLV will be required, which will cover the expanded clay layer. To prevent the screed from sagging in the future, it is best to use expanded clay fraction for screed floor no more than 5 mm.
The essence of preparing the base is to carefully dismantle the old floor covering to the base and to clean the entire area before work is carried out. To do this, you must carefully get rid of debris and dust. If there are cracks, hollow seams and joints with the wall, then they are not well covered with cement mortar. Only after complete drying can you continue to work.
The first layer of the new floor is a vapor barrier, necessary to protect the screed from any condensation, from the lower floor, basement or soil, which can harm its evenness and integrity.
Depending on the type of base, the following types are used:
- for a concrete base - polyethylene with a thickness of 200 microns;
- for a wooden base - paper or parchment with bitumen impregnation;
- special vapor and moisture proof materials are equally suitable for any base.
Laying any of the three types of material is quite simple - lay it on the floor with an overlap of 15 - 20 cm and secure the seams with ordinary tape. The film must necessarily cover the wall to the height of the future screed - about 7 cm. For reassurance, you can leave more. After carrying out the work, cut off the film or bend it during the installation process.
To avoid the unpleasant knocking and grinding of expanded clay filler against the walls, you just need to glue the damper tape that absorbs any sounds. It is connected to the base using PVA glue or double-sided tape.
Exposing lighthouses
To level the future backfill, it is most reliable to install beacons, and not rely on an eye. This will require:
- self-tapping screws;
- laser level;
- rule;
- screwdriver;
- some concrete solution.
Stage 1. Screw a self-tapping screw into one of the corners to the level of the backfill layer. Place the rule on it in an upright position. Place the level in the middle of the room, and where its beam touches the rule on the wall, you need to make a mark.
Step 2. Do a similar step in another corner of the room. If the marks do not match, simply adjust the screws.
Stage 3. When all the markings are made, fix the self-tapping screws to the concrete mortar corresponding to them. It will ensure that the beacons do not move during the backfill process. After the solution has solidified, you can safely continue working.
Screed installation
Step 1. Fill the base with aggregate to the required thickness.
Stage 2. Using the rule and focusing on the level of the exposed lighthouses, properly level the expanded clay layer. It is best to start at the far end of the room, gradually moving towards the exit from the room.
Stage 3. The time has come to lay the GVLV. In order not to damage the leveled base, the sheets need to be mounted from the exit side. This is done quite simply using an adhesive or ordinary self-tapping screws. To make the assembly seam invisible, putty and sand it.
As you can see, installing a dry screed is a simple matter and everyone can cope with it. If you have any questions about its device, you can watch the attached video.
Expanded clay screed based on typesetting technology
Such a screed hardens from two to four weeks, depending on the solution used. Only after this time can you continue finishing work.
There are two variations of surface leveling.
Method 1. Pouring the solution onto a prepared claydite pillow
The preparation of the base is absolutely identical to the process outlined above. After its completion, you can proceed to the subsequent installation.
Installing the frame
Instead of installing small beacons, the frame is being installed. To arrange it, you will need boards with a cut size of 50 * 100 mm. They will be used as spacers to be inserted between parallel walls. They can be replaced with lightweight specialized metal profiles. They are installed at a distance of 30-40 cm, but they are not thoroughly attached, since after pouring the finishing layer they are removed. If you have any questions about installing landmarks, check out the video.
Backfill
The gaps between the frame struts are covered with expanded clay. Its layer should not reach the upper level of the lighthouses by about two centimeters. This gap will go to the concrete pavement device. The rule is to carefully align the aggregate from the far wall to the exit.
Filling with rough mortar
The first layer is a traditional cement-sand mortar. For its manufacture, standard proportions of cement and sand are taken, however, it is necessary to calculate the water so that it is three times more than in an ordinary screed solution. Drying of the first layer should not exceed 24 hours.
Finishing screed device
To complete the screed, special dry mixes are used with the addition of plasticizers, which accelerate the hardening process and give additional strength characteristics. The method of their preparation is taken from the attached instructions.
Specialized mixtures can be replaced with traditional cement and pure river sand mortar. The proportions for him are standard 1: 3. The amount of water should be sufficient for good quality hand placement, but the concrete should not be too runny. To impart special characteristics, plasticizers are added.
The poured layer is carefully leveled and left to harden for the time specified by the manufacturer of the mixture used. After it has passed, the guides can be removed, and the resulting voids are filled with a solution, their surface is leveled. If required by the installation conditions of the screed, it is reinforced with an ordinary metal mesh. But this is more the exception than the rule.
Method 2. Pouring a solution with expanded clay concrete
Preparation and breakdown of the base into working segments using a frame - a lighthouse is carried out according to the above algorithm of work. Only in this case dry backfill is not required. Expanded clay is introduced into the concrete solution in the process of mixing it. It is laid gradually, but quickly enough so that hardening does not occur. The laid mortar is leveled using a rule.
Self-leveling coating on expanded clay screed
A distinctive feature of bulk solutions is their unique composition, prone to self-leveling. In addition, special additives have been added to it, not only accelerating the hardening processes, but also significantly increasing wear resistance and strength.
Otherwise, the method of pouring such a screed is very similar to the process of arranging the first method of leveling the surface on a pre-filled layer of expanded clay. There is only one significant difference - a waterproofing film is laid on the expanded clay backfill, and a self-leveling solution is already applied to it. All air bubbles must be expelled from this layer using a needle roller. Such a screed freezes for at least a week, after which you can safely carry out subsequent finishing work.
There are a lot of methods and technologies for installing screeds using expanded clay. Each has individual characteristics. But they are all pretty simple for an independent device, and the end result is striking in performance. The attached videos will tell you more about how to make a floor screed with expanded clay.
Updated: 01.09.
Of course, there are other technologies, but in some cases expanded clay is recommended:
- the difference in the heights of the base is more than 10 cm. If you put a traditional concrete screed on such a floor, then its weight will create an impressive load on the load-bearing floors. Expanded clay is a light filler that does not overload the structure;
- the base is reinforced concrete slabs. This is a cold material, which is especially felt on the ground floor, and expanded clay insulates the floor;
- the presence of additional utilities and an electric heating system under the floor level;
- limited renovation budget. Expanded clay screed is cheaper than concrete.
The raw material for the production of this material is a special clay that foams under the influence of high temperatures. The result is light, rounded stones, porous inside. They come in different sizes, depending on which it is customary to distinguish three main fractions: gravel, pebbles and crushed stone. Of the useful properties, the following can be distinguished:
- environmental friendliness;
- durability;
- strength;
- thermal insulation;
- soundproofing;
- fire resistance;
- chemical inertness;
- resistance to moisture, heat, frost;
- expanded clay does not rot, mold or mildew does not appear on it;
- low price with excellent quality;
- availability.
It follows from this that the use of expanded clay can not only save the most hopeless floors with holes or a slope of more than 10 cm, but at the same time insulate and soundproof them.
Preparatory work
There are several types of screed using expanded clay, but regardless of the chosen one, some general steps should be taken.
Cleaning and preparation of the base
The base must be cleaned of dust and debris, if possible, remove the old coating, if any. If there are gaps in the floor, then they must be repaired. Wrap the wires laid along the base with polyethylene and seal them with tape at the joints.
Base waterproofing
The purpose of this action is to prevent leaks and damage to the screed. Now for waterproofing, you can use bitumen, purchase ready-made mixtures or roll materials that are overlapped with a large margin, about 15 cm, and are additionally fixed with adhesive tape.
waterproofing
It is also allowed to use a film with a thickness of at least 100 microns, preferably in one piece for the whole room. Foil or other insulating materials are applied to the wall with a margin of height, centimeters by 10, and cut off after completion of the work.
Laying the damper tape
It is attached along the walls, directly to the moisture barrier. The task of the tape is to compensate for the possible expansion of materials due to sudden temperature fluctuations, and in the case of a dry screed, the damper will prevent possible squeaks and other sounds arising from the touch of the coating to the walls.
In order for the floor to be truly level, it is necessary to determine and maintain the level of the screed throughout the entire process of work. For this, the so-called beacons are used.
Using a laser level, the plane of the future floor surface is projected onto the walls of the room, and marks are made at the intersections, which are then connected by a horizontal line. Beacons should be placed along them, taking into account that for expanded clay dry screed, a significant distance from the floor to the profiles should be taken.
Usually, laths or metal profiles are used as beacons. Under them, pre-prepared dies of wood or plywood are placed in order to achieve compliance with the level. When the rows of beacons are installed and verified, you need to fix them with mortar.
This porous aggregate differs in the size of the fractions, so it is best to mix several. Small ones will provide density, and medium ones will not allow the screed to gain weight.
It is important to know that the density of the same fractions may be different, and therefore there are 10 grades of filler. This property of the material should be considered when purchasing.
Denser expanded clay is heavier, but stronger. When all the preparatory work is completed, it is time to start leveling the floor. This can be done in different ways.
Expanded clay is poured onto the prepared base, leveled and rammed. It is necessary that the filler layer does not reach about 2.5 cm to the top of the lighthouse.
Then the evenness of the "pillow" is checked by the level and, if all is well, the solution is carefully placed on the insulation. To avoid shifts and deformation of the base, it is allowed to put a grid on top of expanded clay, or fill it with cement milk so that the granules grab, and the "pillow" itself does not sag over time.
Cement milk is cement diluted with water to the consistency of heavy cream. Expanded clay, filled with such a mixture, must be left for a day to harden. When the pillow is finally ready, it is necessary to lay a solution on it with smoothing movements, the layer of which will turn out to be not very thick, and, therefore, relatively light.
To prepare such a solution, the easiest way is to buy a ready-made mixture at a hardware store and dilute it according to the instructions. This will help you avoid mistakes. If you have experience with concrete and cement, you can prepare the solution yourself.
A floor made in this way will harden in a few days. After this time, the beacons should be removed and the dents from them should be repaired, as well as any irregularities should be sanded. The floor will gain full strength only after 4 weeks, and for all this time it is covered with a film to slow down the evaporation of moisture from the surface. You can do without the film if you moisten the screed with water.
expanded clay
The main advantage of this alignment is the solidity of the screed. The solution will require expanded clay, sand and cement in a ratio of 3: 2: 1. Water will require about two-thirds of the total volume of the remaining materials.
First, water is poured into the mixing container and expanded clay is poured so that it has time to soak. Expanded clay is followed by sand, and only then - cement. The mixture must be mixed until homogeneous with a construction mixer or a drill with a nozzle.
The finished solution must be carefully laid out, leveling with the rule, along the lighthouses from the corner of the room towards the threshold. The distance of expanded clay concrete to the upper mark of the lighthouse remains about 2 cm, since a concrete screed will be laid on top of it. This can be done immediately, without waiting for the first layer to dry. The whole structure will dry as long as the previous one.
Expanded clay + self-leveling floors
Self-leveling floor, provided a suitable base, is the easiest way to get a beautiful, even and perfectly smooth surface. A liquid mixture based on various resins spreads over the surface and smoothes itself.
Such a floor hardens quite quickly, while it is resistant to temperatures, chemically inert, and abrasion resistant. Expanded clay evens out the floor and creates the very base that is necessary to obtain an even coating. It needs to be poured onto the prepared surface, tamped and leveled, focusing on the lighthouses. Then lay a film on top of the insulation and pour the solution onto it. Use a needle roller to roll the liquid mass to get rid of air bubbles and let the floor dry.
This is perhaps the easiest and cheapest way to level floors using expanded clay. Compared to the previous ones, when all the work had to be done quickly, in this case, you can interrupt as much as you like, make corrections, and you do not need to wait for the screed to dry out.
The floor is ready for full use almost immediately. One more advantage of the method should be noted. The finished structure does not contain any cement or sand, therefore it has the lowest weight. This alignment is ideal for older houses with wooden floors where the weight of the screed is critical.
A layer of unfixed expanded clay allows laying telephone and electrical wires, warm floor systems and any kind of communications in it. There are two more advantages to this method of leveling the floor: better sound insulation and heat retention, and the only disadvantage is the fear of moisture in the covering sheets.
The steps are very simple. The dry expanded clay mixture is scattered on the floor, compacted and. It is possible to level not the entire floor at once, but in fragments, since you still have to walk along the backfill. As for the thickness, it is determined by the specific situation. Already 3-4 centimeters of filler allow you to create a sufficiently dense and stable coating, but you should not do a smaller thickness.
Sheets of floor material are laid on the tamped pillow. It can be gypsum fiber board, OSB, fiberboard, chipboard and just plywood. The sheets are placed relative to each other according to the brickwork principle, that is, the side of each sheet is in contact with the halves of the sides of the other two.
GVL sheets
The folds of the slabs are usually glued together, and a second layer is laid on top, attached to the first with self-tapping screws. The resulting coating should not reach about a centimeter to the wall, these gaps will be hidden later by the baseboards. In the resulting structure, all joints are putty, and the topcoat is laid on top of the finished floor.
So, leveling the floor with the participation of expanded clay can rightfully be considered an economically correct choice that has a lot of advantages. The method has alternatives, but it does not lose its popularity, as it allows you to achieve the goal, avoiding many problems. Competently carried out work allows you to get a really flat and durable floor that will not need repair for a long time.
Video - Leveling the floor with expanded clay
One of the basic requirements for any home, be it your own house or apartment, is a warm, comfortable microclimate in it. And only the heating system cannot solve this issue. No matter how powerful an autonomous boiler or central heating radiators are, the required result cannot be achieved without reliable thermal insulation of the premises.
In order for housing to become invulnerable to the vagaries of weather both in winter and in summer, almost all of its elements should be insulated - walls and curtains, windows and doors. But the floors are always given increased attention - this is especially important for the owners of their own houses and residents of the lower floors, under whose apartments unheated rooms are located. A cold floor in winter is a feeling of constant discomfort, a direct path to illnesses of people living there, and plus to this - constant huge losses of thermal energy, which invariably affect the family budget. How to solve this problem? There are many options, and one of the most effective is a do-it-yourself floor screed with expanded clay.
Why it is worth choosing exactly expanded clay, what types of screeds are used with it, how difficult they are in independent execution - this publication is devoted to these issues.
Basic properties of expanded clay
Even though a lot of modern insulation materials on a mineral or synthetic basis are presented in construction stores, expanded clay remains an extremely popular material due to its versatility, environmental friendliness and excellent performance characteristics.
What is this material. It is obtained using the technology of special processing of specially selected varieties of clay. Raw materials go through the stages of drying, grinding, thorough cleaning from impurities and organic residues - this is very important for obtaining really high-quality expanded clay.
Then the prepared clay is diluted to the required consistency, and granules are formed from the resulting mass in special drums, which are subjected to high-temperature firing (about 1100 ÷ 1200 degrees). Such a sharp thermal "shock" contributes to the effect of pyroplastics - explosive gas separation (due to water vapor and thermal decomposition products of some raw material components), followed by rapid solidification to obtain a strong porous structure.
At the exit from the technological line, granules of red-brown or yellowish-red color are obtained with an external melted crust, which to a certain extent protects expanded clay from moisture penetration into its porous structure.
As you can see, no chemical additives are used in the manufacture of expanded clay, and if the manufacturer uses really high-quality natural raw materials, without adding industrial waste (for example, slags), then the material is absolutely clean from the point of view of ecology.
In addition, expanded clay has a number of positive qualities:
- The material, due to its porous structure, has excellent insulating qualities. The coefficient of its thermal conductivity, depending on the grade, lies in the range from 0.07 to 0.16 W / m × ° C.
- At the same time, the material has a fairly high mechanical strength - depending on the density, it ranges from 0.6 to 5.5 MPa.
| Expanded clay grade by bulk density | Keremzit of the highest quality category | Expanded clay of the first quality category | ||
|---|---|---|---|---|
| Strength grade | Ultimate strength, MPa, min | Strength grade | Ultimate strength, MPa, min | |
| M250 | P35 | 0.8 | P25 | 0.6 |
| M300 | P50 | 1 | P35 | 0.8 |
| M350 | P75 | 1.5 | P50 | 1 |
| M400 | P75 | 1.8 | P50 | 1.2 |
| M450 | P100 | 2.1 | P75 | 1.5 |
| M500 | P125 | 2.5 | P75 | 1.8 |
| M550 | P150 | 3.3 | P100 | 2.1 |
| M600 | P150 | 3.5 | P125 | 2.5 |
| M700 | P200 | 4.5 | P150 | 3.3 |
| M800 | P250 | 5.5 | P200 | 4.5 |
M- Bulk density grade. For example, M450 corresponds to 450 kg / m³
- Expanded clay is absolutely non-flammable material. When exposed to flame, it does not emit any toxic substances that can harm the human body.
- The material is not a breeding ground for microbiological life forms. In addition, expanded clay becomes an insurmountable obstacle for.
- In addition to high insulating qualities, one cannot fail to note the ability of expanded clay to absorb noise - it becomes an excellent soundproof material.
- Expanded clay, despite the fact that it still absorbs moisture, is absolutely not subject to decay processes.
- The material is not afraid of temperature changes in a very wide range - its insulating qualities do not change from this.
- Plus to all of the above - the material significantly wins in its cost from many modern heaters - it practically availableto allaverage consumers.
Expanded clay comes on sale in various forms. As a rule, at enterprises the main type of products is coarse gravel with granules from 20 to 40 mm. When sorting, smaller fractions are sifted out - this is how expanded clay crushed stone with grains from 5 to 10 mm is obtained. Smaller waste and disintegrated granules are crushed to obtain expanded clay sand (0 ÷ 5 mm) or sand-crushed stone mixture (0 ÷ 10 mm). All these types of material, however, are widely used in construction in one way or another. True, their physical and operational characteristics are already somewhat different.
| Parameters | Expanded clay gravel 20 ÷ 40 mm | Expanded clay crushed stone 5 ÷ 10 mm | Expanded clay sand or sand-crushed stone mixture 0 ÷ 10 mm |
|---|---|---|---|
 |  |  |
|
| Bulk density, kg / m³ | 240 ÷ 450 | 400 ÷ 500 | 500 ÷ 800 |
| Thermal conductivity coefficient, W / m × ° С | 0.07 ÷ 0.09 | 0.09 ÷ 0.11 | 0.12 ÷ 0.16 |
| Water absorption,% of the volume | 10 ÷ 15 | 15 ÷ 20 | no more than 25 |
| Weight loss,%, during freezing cycles (with standard frost resistance grade F15) | no more than 8 | no more than 8 | not regulated |
Obviously, the better the expanded clay, the larger its fraction, the lower the bulk density and the higher the thermal insulation capacity. However, the use of large granules in some cases is simply impossible due to the peculiarities of the technology, flooring devices - this will be discussed below.
Sometimes one can come across statements that expanded clay creates a certain radiation background. To this one can answer that if the material is produced by enterprises with exact adherence to GOST standards, then it is absolutely safe, and its specific active efficiency (AEff) should be in the range of 200 ÷ 240 Bq / kg, with a permissible sanitary standard of 370 Bq / kg. But if material is purchased absolutely unknown origin - caution does not interfere. In any case, you should always ask the seller what kind of enterprise produced expanded clay, and whether there is a necessary quality certificate for it.
Expanded clay prices
Expanded clay
What are floor screeds with expanded clay for?
The listed physical qualities of expanded clay make it sometimes indispensable for
- In private construction, when the floors in a country house are arranged directly on the ground, this material has no competitors at all - it will allow both to raise the level to the required level and to provide appropriate thermal insulation from the cold coming from below.
- Do the same if you want to insulate the floor, the base of which is a reinforced concrete slab, under which there is no heated room.
- A screed using expanded clay becomes a reliable sound insulation barrier if, for example, a constant source of noise is located below.
- With large differences in the level of the base surface, expanded clay allows you to very significantly save on building materials - a thick screed with expanded clay is incomparably cheaper than pure concrete. In addition, the preparation and pouring process takes much less time.
- Due to the fact that the material is light, a screed with expanded clay will not exert an excessively high load on the floor slab.
- It is quite possible to place engineering and electrical communications under such a screed.
- Very widely used expanded clay-concrete screeds for the arrangement of "warm floors". They become not only a reliable basis for laying out the contours of pipes or heating cables, but also an effective thermal insulation cushion, which most warm floors simply cannot do without.
Do you want to build a "warm floor" in the room?
It will be effective only if all the requirements for thermal insulation of its base surface are met.
For more information about the technologies for laying underfloor heating, or read in special publications of our portal.
There are few disadvantages of a screed with expanded clay.
- The first of them mainly concerns those screeds that are arranged according to the classic "wet" technology. The point is that when arranging such a coating, the floor level rises significantly - usually at least 100 mm. It is clear that this is not possible in all rooms simply because of the insufficient height of the ceilings.
- The second disadvantage is inherent in floors with the so-called "dry screed" with expanded clay. Unfortunately, such coatings do not differ in water resistance - spilled water, if it managed to penetrate into the thickness of the expanded clay layer, will not come out of it by itself, and in order to eliminate this "hotbed of dampness", you will have to resort to dismantling.
And now let's move on to considering the basic technological methods for creating a floor screed with expanded clay with our own hands. As already mentioned, there are two main approaches - "wet method" pouring with one or another variation in the sequence of work, and "dry heavy" backfill followed by decking on top of the sheet material.
Pouring screed with expanded clay "wet"
This method is applicable, along with a high leveling height of the surface, it is required to give semi additional sound and thermal insulation qualities, at the same time preventing too high a load on the floor slab. It is also perfect for installing an insulated floor on the ground (provided that a concrete base with a primary insulating layer is already poured, which is also widely used the same expanded clay).
Schematically, a "wet" screed with expanded clay can be depicted as follows.
1 - floor slab or rough screed on the ground.
2 - the wall of the room.
3 - waterproofing layer. Expanded clay, as you can see, is a fairly hygroscopic material, and so that it does not absorb moisture, capillary coming from the ground or in the form of steam - from the premises below, a layer of hydro-vapor barrier is a prerequisite.
4 - an elastic damping tape, which is used with most types of ties according to modern technologies. It compensates for the thermal expansion of the resulting concrete slab, preventing its deformation and destruction.
5 - a layer of expanded clay, at least 50 mm thick, and if insulation of the floor of the first floor or in a private house is required, then the minimum thickness reaches 100 mm.
6 - a system of beacons that predetermines the level of the created floor. The diagram is not clearly shown, but together with the beacon system, the reinforcement of the upper screed is also most often laid.
7 - cement-sand screed, which will become the basis for the further laying of the topcoat or floor heating system.
Now - specifically to the technology of laying such a screed.
Floor surface preparation
Any screed should be flattened onto a carefully prepared surface. No excuses about the fact that layers of expanded clay and concrete will hide all the shortcomings are absolutely unjustified. Substrate defects left at the beginning of work may then appear on the finished floor covering.
- First of all, the surface condition is checked. If there is an old screed on the floor, then you need to make sure that it is stable, without delamination, areas of erosive decomposition of concrete, its crumbling, etc. In general, since it is planned to insulate the floor with a sufficiently thick layer of expanded clay, the wisest decision would be to get rid of the old screed by dismantling it to the ground.
This work, of course, is not the most pleasant and easy, but, armed with a puncher, the owner will solve several problems at once. Construction waste is immediately taken out so that it does not interfere with further operations.
- After thorough cleaning of debris, it is worth carefully examining the opened surface. If there are slots on it with a width of more than 1 mm, then they should be cut for subsequent filling with a repair compound. If oiled areas are found, they are cleaned out to clean cement.
- Then, all areas requiring repair are dedusted and treated with a deep penetration primer to achieve the required adhesion with the repair compound.
In its capacity, ordinary cement-sand mortar can be used, but it is still better to purchase a special one- or two-component putty (or sealant) on an epoxy or polyurethane base - and the repair will be of better quality, and the "patches" will harden faster, and for waterproofing the repaired site will not have to worry.
The best option is special repair putties for concrete The composition is filled in all the cut cracks, potholes, leveling with a spatula under the main level of the base of the floor.
After the time for complete polymerization established by the instructions of the repair composition has been maintained, the entire floor surface after the next cleaning with dust removal is recommended twice. After complete drying, the surface can be considered ready for further stages of work.
Beating "zero" level
The surface of the floor has been prepared - it is repaired, cleaned, not dusty. But before proceeding to further installation work, you should immediately determine the height of the future screed. In a word, it is required to beat off the "zero" line, marking the level at which the top layer of the created coating will fall.
The easiest way to do this is to use a laser level - it will very quickly and accurately mark the necessary lines on the walls. However, it proceeds from the fact that this article is designed for people who are engaged in such a business for the first time, and they do not have such a tool, and it is hardly advisable to acquire it to perform a one-time job. It is easier to buy the simplest water level - the marking accuracy will not suffer from this.
In addition, you will need a building level, a long metal ruler (for example, a rule), a pencil or marker, and a tape measure.
- To begin with, purely visually, the highest point in the room is approximately determined. Further markup will go from here.
- It is very difficult, and sometimes impossible, to carry out accurate markings with a hydraulic level right at the floor surface, so it is best to draw the first baseline at a convenient height - you can, for example, take 1500 mm from the level of the subfloor. At this height, a mark is made on the wall with a marker.
- Then, using the water level, this height is transferred to all the walls around the perimeter of the room.
The property of communicating vessels, which are the flasks of the hydrolevel, allow this to be done with the utmost precision.
An approximate scheme for determining the "zero" level - Applied marks (shown by wide red arrows) connected by a straight line - this is how the reference line is obtained, which is located strictly horizontally (shown in blue in the diagram).
- From this line, approximately every meter, measurements are taken from the level of the floor surface (black curved line). The values are transferred to the drawing or even simply written in pencil on the wall at the measurement point. (on the diagram - green arrows with the corresponding inscriptions). Such measurements will help to accurately determine the highest point in the room.
- Now you need to apply the "zero" level. Let's say the total height of the screed with expanded clay is planned to be 130 mm ) 100 mm - a layer of insulation and another 30 mm - the cement-sand screed itself. At the highest point, a simple calculation is carried out. For example, the height from the floor level to the base blue line is 1500 mm. This means that the distance between the base line and the "zero" level will be equal to 1500 - 130 = 1370 mm. From the baseline, it makes a measurement strictly vertically at the calculated distance, a risk is applied. (the height of the screed is shown with a blue arrow )
- The same marks with a calculated height of 1370 mm are made at all other points of the sounding. As a result, we get a chain of marks, after connecting which along the ruler on the wall there will be a perfectly accurate line of the "zero" level (shown in red in the diagram).
- After the line is drawn, it is worth performing another important check. It is necessary to stretch the cord along the mark made across the room in several places, and check the height from it to the floor in the center of the room. It is not often, but it happens that there is a "hump" in the center of the room, and the height of the resulting screed in this area will turn out to be less than planned. If you had to face such a circumstance, then you will have to raise the overall zero level somewhat to the required height.
Now you can proceed to further actions.
Laying the insulation layer and pouring the screed
The next step is the hydro - vapor barrier of the base floor surface. The main task, as already mentioned, is to prevent moisture from entering the expanded clay layer from below (capillary or in the form of water vapor passing through the floors).
- If the floor is equipped in a private house on the ground, then you should not stint and make high-quality insulation from roll materials such as roofing material. It is best to lay it in a "hot" way on bitumen mastic, carefully gluing adjacent strips on the overlaps (at least 100 mm). The waterproofing layer must necessarily rise on the walls on level above the planned screed.
In the event that a screed with expanded clay will be poured over a concrete slab, then such a measure may be excessive - it will be quite a dense polyethylene film with a thickness of at least 200 microns. The canvases are laid with an overlap of 150 ÷ 200 mm, and must be glued in these places with waterproof construction tape. The film should also go on the walls above the level of the future screed.
- If you plan to leave certain communications under the screed, then they should be immediately prepared for this. The cables should be hidden in plastic, the pipes are hermetically wrapped with plastic wrap.
- The next step is to strengthen the damper tape around the perimeter of the room, which will absorb the thermal linear vibrations of the screed.
They purchase a damper tape in such a way that its width is greater than the height of the planned screed - the protruding excess after the end of the work will be easy to cut off.
Fasten the damper tape in such a way that the edge of the waterproofing film extending onto the walls is under it (see the diagram above). You can fix it in different ways - on an existing self-adhesive layer or using pieces of scotch tape. The main thing is that it should be laid on all vertical surfaces - walls, openings, niches, columns, etc.
On the floor - plastic wrap, on the walls - damping tape The next step, it would seem, should be the installation of a beacon system. However, the further course of work may differ somewhat.
BUT. You can do the following.
- For the whole waterproofed the surface of the floor is covered with expanded clay (it is best to use large-fraction, from 10 ÷ 20 to 20 ÷ 40 mm - it is less dusty, and its insulation qualities are higher). The backfill layer is selected in such a way as to leave space for the concrete screed from above, at least 30 mm. When backfilling, it is necessary to compact expanded clay, for example, by tamping it with a wide plastic or wooden plaster float.
- Then this insulation layer is spilled with a liquid cement solution (cement "milk") and left for a day so that the expanded clay granules are somewhat connected with each other, and it was possible to move along them to perform subsequent operations. Another option is to "redeem" expanded clay in advance in cement milk in a concrete mixer, and then spread it on the floor.
- After the layer of insulating expanded clay backfill acquires a certain strength, you can lay the reinforcing mesh and expose guides - beacons for filling the screed. There are a few important points to make here:
- A serious mistake is made by those who lay the reinforcement belt close to the bottom layer. It turns out that the mesh takes little part in, in fact, the reinforcement of the screed - it is, as it were, “stuck from below, and often some of the rods are not even completely immersed in the solution from all sides. It will be optimal to place it so that it fits approximately in the center of the future concrete screed. To do this, you can use linings made of pieces of concrete, ceramic tiles, etc., or purchase special plastic racks that will raise the reinforcement to the desired height.
- Guide beacons are most often made of galvanized plaster profiles. In our case, it is simply impossible to apply the technology of installing beacons using self-tapping screws, adjustable in height. This means that the best option would be to fix them on the slides of mortar. And here some "masters", seeking to speed up the process, make another mistake, using gypsum-based building mixtures. Yes, they will of course freeze and fix the beacon in a given position very quickly, but only the quality of the screed will seriously suffer from this.
The fact is that the physical characteristics of cement and gypsum differ very seriously - in terms of water absorption, strength, linear expansion, degree of shrinkage, etc. This means that the design of the screed turns out to be heterogeneous, and then there will be no need to be surprised that creases will go along the lines of the lighthouses. Ideally, the slides for fixing the beacons should be made of the same mortar as the screed will be poured into. It's okay, you can wait one day to achieve a quality result.
Beacon profile on a plaster slide - a weak point of the screed Beacons are set strictly along the previously outlined "zero" line, their horizontal position and location in one plane is carefully controlled with the help of a building level. The distance between adjacent guides is chosen so that on the rule was free to move with it, with a margin of at least 200 mm on each side - for lateral movements when leveling.
- After the beacon system has received sufficient stability, they proceed to pouring the screed. To do this, you can prepare an ordinary cement-sand mortar (3: 1), which it is desirable to "fertilize" with a special plasticizer sold in a hardware store, and fiberglass micro-reinforcement. If there is a financial opportunity, you can also purchase a ready-made screed mortar with an already balanced modified composition.
- The screed is poured in the usual way - the ready-made solution with a slight excess is laid out between the guides. Measures are taken to ensure that no air voids remain - distribution is carried out using a spatula or trowel, with piercing of the mass to release air bubbles. Particular attention to areas along the lighthouses and reinforcement posts - the mortar must fill all possible cavities. Then the final alignment of the screed is carried out according to the rule of the beacons.
- After the screed is completely poured, it is left to set. Then, after 10 ÷ 12 hours, in order to exclude drying out and cracking, it is advisable to moisten it with water and completely cover it with plastic wrap. If necessary, moisturizing can be repeated periodically.
- After about a week, it will be possible to move fearlessly along the screed. In the same period, protruding above surface upper the edges of the plastic film and the damper tape. But it is too early to start further construction and finishing work - the full maturation of concrete will come only after a month. True, if modified building mixtures are used for screeds, then the period may be shorter - this is necessarily indicated on the packaging of the composition.
B. The second method is slightly different. According to this technique, the system of beacons and reinforcement is installed immediately, on waterproofed surface.
- It will take two posts to prepare the solution:
- One (for example, a concrete mixer) prepares a thick solution of cement, sand and expanded clay in a ratio of 1: 2: 3. In this case, expanded clay is first poured into the water, so that it absorbs the required amount of moisture. Then, during mixing, the required amount of the remaining components is added. The composition should turn out to be "tight" - plastic enough for smoothing, but not spreading when laid out.
- at the second post (for example, using a manual electric mixer), a solution is prepared for the floor screed itself - cement-sand or from a ready-made mixture.
- With this technique, laying both layers the coating is made stepwise. First laid out concrete-expanded clay mortar on an area up to 1 m wide - so that you can reach it with the rule.
- After leveling this layer, leaving about 30 - 40 mm from the level of the beacons, immediately laying out the composition for the screed and leveling it along the guides follows. At the same time, about 150 — 200 mm to the edge of the first layer.
- Further, the operation is repeated: the expanded clay concrete layer - and then the screed itself.
To be honest, this approach does not look optimal. First, expect big wins by time, compared with the first method, it is not necessary. Second, a very good consistency is needed between workers preparing two different solutions at the same time. And thirdly, the insulating qualities of the resulting "pie" will still be seriously inferior to the first option.
IN. Finally, the third way to fill the screed.
In this version, the entire poured layer, from the base to the upper level of the beacons, consists of concrete-expanded clay mortar. It would seem that everything is simple and convenient, but this is not entirely true.
- Expanded clay is much lighter than water, so it will always tend to float to the surface in the solution. This means that it is unlikely that it will be possible to level the screed, as with ordinary concrete, it will still remain bumpy and rough.
- Second minus. Granules or particles crushed expanded clay, used as a filler, are significantly inferior to quartz sand in terms of their strength properties. And this means that the surface will not be so strong - it will be characterized by looseness and increased dust formation.
To some extent, such a drawback can be minimized by grinding the top layer and impregnating it with special strengthening compounds - and this is unnecessary material and labor costs. Another option is to pour a layer of self-leveling compound over this screed, which will also require additional costs.
For laying ceramic tiles, this is a very good option. The screed is the main structural layer of any floor on which the finishing flooring is laid. It is necessary, first of all, in order to level the base. The service life of the floor depends on how well the screed is made. The most popular in household construction is a screed on an expanded clay layer. What features distinguish this type of screed, what laying options exist, and which expanded clay to choose for construction work - read below.
Lightweight screed with expanded clay in terms of performance, the level of sound insulation is superior to sand mixtures, cement screed. Such a base does not corrode, breathes well and does not require frequent repairs.
The main advantages of screed with expanded clay include:
- Strength. Expanded clay screed easily withstands a load of 500 kg per square meter.
- Environmental friendliness. The material is hypoallergenic and does not emit toxic substances.
- Fire safety. The material is explosion-proof and non-flammable.
- The speed of installation work. Laying a dry screed on a flat base is carried out by a team of workers in 3 hours.
- A light weight. Such a screed is much lighter than conventional concrete.
Like any other material, expanded clay has its drawbacks. These include poor sound insulation and hydrophobicity, which in both cases can entail the cost of organizing additional layers (for example, waterproofing).
Scope of application of screed with expanded clay
A floor screed with a layer of expanded clay concrete is used as a base for finishing with any finishing floor materials (laminate, linoleum, tiles). In addition, a self-leveling (liquid) floor is easily laid on such a base, which you can fill with your own hands.
A screed with expanded clay can be used both in household construction and in organizing pilaf of warehouse, industrial and commercial premises.
Expanded clay concrete screed is used for thermal insulation. In addition, communications can be easily hidden in the backfill floors (for example, underfloor heating). Expanded clay is also needed if the floor is "bunching", has cracks. An expanded clay screed may be needed if it is necessary to level the base (the floor has differences in the height of the relief of 10 cm or more).
Screed with expanded clay: technology and preparation of the base
Screed with expanded clay can be done wet, semi-dry and dry. Options are selected depending on the size and purpose of the room. Regardless of the method chosen, the screed installation technology involves careful preparation of the base for construction work.
Preparation of the base for the screed includes the following stages:
- Removing the topcoat (cleaning the floor to the base if it is covered with a light material such as linoleum).
- Cleaning the floor from construction debris, dirt.
- Leveling the base. The floor is putty from cracks and chips. You can level a floor with large differences in height using a scraping (for a wooden base), concrete mortar, plywood.
- Laying the waterproofing layer. Waterproofing is necessary for any type of screed with expanded clay.
- Installation of lighthouses. Lighthouses are set at a laser level and fixed with cement mortar. Further work should be carried out only after the cement mixture has dried. How much cement dries depends on the manufacturer of the material, temperature and humidity in the room.
After preparing and cleaning the base from construction debris and dust, you can lay the screed.
Dry screed with expanded clay
Dry expanded clay screed is very popular for flooring, both in apartments and in office premises. The technology for laying a dry screed is quite simple: a layer of hydrolysis is laid on the base (for example, a polyethylene film), which is covered with expanded clay. GVL plates are placed on top.
However, laying a dry screed has some nuances:
- The screed installation instructions indicate that expanded clay should be poured only on an even, clean and dry base.
- Hydrolysis should be overlapped, the film joints should be fixed with construction tape, along the perimeter - with a damper tape.
- To level the expanded clay well, you should set up beacons. Lighthouses are removed after covering part of the base with material. If necessary, filling is done.
- If you need an insulated screed, then in order to make a "pie" you should use fine expanded clay and sand.
- Expanded clay should be backfilled in portions, starting from the far corner of the room. After filling one area, the sheet material should be laid immediately, pressing it well against the layer.
- Leave a gap of a few mm between the boards. The seams between the panels must, without fail, be putty
Semi-dry expanded clay screed
A semi-dry screed is a combination of wet and dry: it is the same two-layer as wet, while the expanded clay and waterproofing layers are laid on the dry principle. Such a screed is used in rooms with a base, the differences in the height of the relief of which exceed 15 cm.
In order to lay the screed correctly, you should adhere to the following sequence of actions:
- On a leveled, dry base, lay waterproofing and install beacons.
- Fill up with expanded clay gravel (thickness not less than 800 mm).
- Align and compact the layer so that no voids remain in the pillow.
- Stick a damper tape around the perimeter of the room, above the level of the screed.
- Place fiberglass (80-90 grams per square meter) or reinforcing mesh on the gravel layer.
- Pour a layer of sand and cement mixture over the installed lighthouses (thickness 40-50 mm). Pouring should take place quickly, since the composition begins to solidify from 40 minutes after preparation
Thus, you can make a floor device in a warehouse, garage. The floor can be poured using special equipment quickly (for example, a concrete pump). At the same time, it is necessary to level the coating manually, as a rule, focusing on the set level.
Expanded clay for floor screed: fraction
Expanded clay for screed is classified according to the shape and size of the fraction. Which fraction is better to choose for floor screed depends on the purpose of expanded clay. Most often, a fraction of 0.5-10 cm is used for floor screed. The use of a fraction of 1-2 cm can increase the density of the layer.
Today, the following types of expanded clay are distinguished:
- Gravel (expanded clay). The material is characterized by rounded brown granules. The size of the granules can vary from 5 mm to 4 cm.
- Crushed stone. Angular fraction (obtained from crushed foamed clay), can be either minimum or maximum size.
- Sand (expanded clay). The size of the granules of such material does not exceed 5 mm. Most often it is used for lightweight, thin screeds in apartments.
Smaller fractions are used for household construction, larger ones - for warming the floors of living rooms and basements, roofs. Expanded clay gravel is often used as an insulating layer.
Which expanded clay is better for floor screed: the composition of expanded clay concrete
The proportions of ingredients for screed with expanded clay depend on the method of installation. So, for a wet screed, it is necessary to take cement, sand and expanded clay in proportions of 1: 3: 4.
A different ratio of components allows you to get expanded clay concrete of different classes and brands.
In order to obtain expanded clay concrete of the M150 brand, it is necessary to observe the following proportions of ingredients: 1: 3: 6. To obtain the M400 brand, the solution is prepared from ingredients in a ratio of 1: 1.5: 3. On average, a bucket of cement and 0.05 tons of sand are consumed per square meter of a 30 mm thick screed.
In order to prepare a solution of expanded clay concrete mixture, it is necessary to pour expanded clay into a deep container and fill it with a small amount of water. Expanded clay is left for some time so that the granules swell. After that, binders are added to the container: cement or sand concrete. All components are mixed with a construction mixer to a thick consistency. After the expanded clay has acquired the color of cement, the solution is considered ready.
Leveling the floor with expanded clay with your own hands (video)
A screed with expanded clay layer is a reliable and simple method that allows you to achieve a flat base with high performance characteristics. At the same time, construction work will not hit the pocket: prices for expanded clay differ in their availability. You can make a screed with your own hands. The main thing is to take a responsible approach to the process of preparing the base and laying the layers, and then you will receive a high-quality floor for covering with any finishing material!