When repairing a floor, a screed is a must. This type of screed, like everything else, can be prepared using sand obtained from expanded clay, which is a fine-grained building material, the particles of which are up to 5 mm.

Lightweight expanded clay concrete, like expanded clay screed, can be made at home.

Especially if the manufacturer of concrete and screed mortars is located far from the construction site. Making environmentally friendly and warm expanded clay concrete with your own hands will allow you to get the necessary building material not only in the right amount, but also with the required structure and correct composition.

Expanded clay is one of the most popular materials used for floor screed. You can prepare a solution of expanded clay concrete with your own hands using the recommended proportions.

The proportions for the expanded clay concrete solution are as follows: 1 part of cement, 3 parts of sand and 8 parts of expanded clay. Concrete can be made from such types of expanded clay as sand, gravel and crushed stone, which are maximally adapted for the production of concrete blocks and coatings.

Preparation and transportation

Solution making process

To make a high-quality solution using expanded clay concrete, you need to adhere to the recommended proportions. With the correct dilution of the mixture, the screed will turn out to be of high quality and durable.

Tools and devices that will be needed in the process of preparing a claydite concrete solution:

1. Pneumatic blower with mixing hopper or concrete mixer with a volume of 200 liters with a construction trough (200 liters).
2. Flexible hoses for transporting the mix or a shovel with a bucket for pouring the floor.

The list of required materials should include the following components:

1. Cement (M400 or M500).
2. Washed quarry sand.
3. Expanded clay (fraction 5-10).
4. Water, from 200 to 300 liters per cubic meter, which is determined by the moisture content of the materials.
5. Plasticizer - laundry soap or washing powder.

Before mixing the expanded clay concrete mixture, the mixture, the expanded clay granules must be moistened with water in order to improve the adhesion properties of the solution.

Preparatory work for the arrangement of expanded clay concrete in the formwork is reduced to preparation. Before you start mixing the expanded clay concrete mixture, the expanded clay granules are moistened with water to improve the adhesion property of the solution with the addition of sand with cement.

Instructions for preparing one batch of expanded clay concrete include the following steps:

1. Switch on the concrete mixer or pneumatic blower.
2. Fill in water.
3. Add cement.
4. Fill up with sand, observing the required proportions.
5. Stir the mixture thoroughly.
6. Pour expanded clay into the solution, observing the correct loading of the tank.
7. Get a homogeneous mixture of expanded clay concrete with a volume of 200 liters.

The whole process of preparing one batch of expanded clay concrete will take about 3-4 minutes. In the process of performing work, the consistency of the composition is carefully monitored. A high-quality solution can be in the form of plasticine or sour cream of a thick consistency. If necessary, add water to reduce the density. When a more liquid consistency is obtained than is provided by the instructions, such concretes are simply mixed after a short settling. To obtain more homogeneous concrete, dry mixing is used, that is, only dry components are taken, and then water is added and mixing is performed.

Use of ready-made expanded clay concrete

After the work on laying and leveling the expanded clay concrete solution is completed, it is necessary to let the surface dry for 1-2 days.

To start pouring concrete, after finishing the preparation of the mixture, prepare buckets with shovels, or flexible hoses for transporting the solution. The ready-mixed claydite concrete is transported using hoses through which the solution flows under the influence of compressed air. Small portions of the solution are fed through a rubber hose under pressure to the place where the layers of expanded clay concrete are laid. In the presence of a damper, the working pressure is reduced and the solution is poured in small portions onto the floor inside the room.

After completing all the work on laying and leveling the expanded clay concrete solution, the surface is left for a day or two, then it will be possible to walk on the hardened surface, but the longer the surface dries, the more reliable and durable the flooring becomes.

Expanded clay will not only improve the quality of the floor screed, but also is an excellent material for warming indoor floors.

The solution that came from the extinguisher must be evenly distributed over the entire floor of the room up to the required mark. With the help of light tamping, each unevenness is filled with expanded clay concrete, while providing additional thermal insulation for pipelines and heating.

Since the expanded clay concrete solution does not retain the required viscosity for long, it is used in the process of pouring floors immediately after preparing the mixture. In this case, a sealed formwork for pouring is pre-assembled.

For the manufacture of expanded clay blocks using special forms for pouring concrete, they are installed on pallets, and in the process of pouring, shovels or buckets are used. It is impossible to apply any mechanical influences to the poured concrete, therefore it is left to fully harden for a day or two, and then the formwork is removed from the blocks. When all the work on the expanded clay concrete preparation has been completed, preliminary work on the preparation of the cement-sand screed is performed.

For leveling expanded clay, it is necessary to use a dry mixture. To do this, add water to the mixture until the solution becomes viscous and homogeneous.

For high-quality compaction and leveling of expanded clay, it is used dry, not wet. Water is added to the prepared solution with expanded clay until it becomes viscous and homogeneous. M100 solution is taken in the ratio of one part to three to four parts of expanded clay. While kneading, it is necessary to monitor its fraction. This grade of mortar will prevent the appearance of cracks as a result of an overabundance of cement. To prevent the appearance of splits in the screed, water is taken in not very large quantities. In this case, the size of the calculated cake of the cement screed should be more than 10-12 centimeters.

The implementation of a two-layer screed is necessary if large differences are found on the base where the future screed will be laid, if the horizontal is observed over the entire area at a level of ten centimeters or more. In order to efficiently carry out all the work on the installation of a floor screed with expanded clay and normal cement mortar, you must follow the instructions below, carefully observing all proportions:

1. Mix expanded clay with mortar using a mixer or an electric drill with a mixer attachment.
2. Starting the preparation of the second layer of screed, knock down all protruding sharp parts on the floor. The indentations are compared to the common sub-floor.
3. Lay in plastic sheeting for waterproofing. You can use waterproofing or liquid mastic.
4. To make the flooring of the isolon, fixing it with adhesive tape around the entire perimeter. It is possible to raise the material higher than the level of the screed.
5. Install masonry nets, if necessary.
6. After filling with expanded clay and leveling, wait two or three hours until all the water is absorbed into expanded clay, and start installing beacons, which are metal slats or profiles.
7. Pour the base layer with a finishing solution of a leveling cement-sand screed, for strength add a plasticizer that prevents the appearance of cracks. The thickness of the layer should be about 40-50 centimeters for a mixture of gypsum plaster and tile adhesive.
8. Leave the finished screed to dry for a month.
9. Regularly wet the floor surface with water to prevent cracking.

In this way, you can save money by reducing the overall stress on the sub-floors. This technology, with its strict observance, allows not only to make the floor new and of high quality, but also to obtain a lighter screed, in comparison with other types that have high sound and heat insulation.

As mentioned above, expanded clay acts as the main material of this type of screed, which is of several types:

• Crushed stone. This material is characterized by the largest fractions - from 5 to 40 mm. The recognizable oval shape is missing. Expanded clay concrete with a crushed stone base is used for "wet" pouring.
• Gravel. This material has several categories in relation to the size of the fractions. The first group consists of granules ranging in size from 5 to 10 mm. The second group consists of fractions from 10 to 20 mm in diameter. The third type of gravel is from 20 to 40 mm. All the listed standard sizes are ideal for "wet" and "semi-dry" screeds.
• Sand. These particles are obtained in the process of sieving expanded clay granules after heat treatment of the material. The size is less than 5 mm. It is used for "dry" floor screed and for pouring a thin layer.

Thus, it is possible to determine what type of expanded clay granules to acquire in relation to the pursued final results of the screed.

For example, to ensure good sound insulation of the room, it is advisable to use gravel for screeds with a height of 60 mm and more. Crushed stone can also be used for a "wet" screed. The only difference with the "semi-dry" method is that the concrete solution with pre-soaked granules is mixed after placing the beacons. Moreover, the work is carried out simultaneously, and not in stages - that is, expanded clay concrete is poured between the installed beacons, after which a leveling concrete layer is immediately applied.

Gravel mixed with sand can be poured directly under the floorboards. As a rule, the height of the lag allows you to make a similar filling.

What amount of expanded clay is necessary for the implementation of the floor screed is also an urgent question. In a network of special trading platforms, construction expanded clay is sold, packaged in 50-liter packages. This amount is enough for 1 m2 of surface, taking into account the height of the screed 40 - 50 mm. Based on this formula, you can easily calculate the amount of expanded clay for any area.

In old apartments or houses, after removing the wooden floors, the distance from the overlap to the level of the finished floor is very large. The load-bearing capacity of the floor does not allow it to be collected by means of a concrete screed. In this case, there are two options - sheet material on logs or expanded clay concrete screed. A similar situation occurs in a private house when they want to replace the wooden floors.

Expanded clay concrete is the so-called lightweight concrete, in which expanded clay is used as an aggregate. It is usually used where the screed layer is large. This means that the floor load will be significant. Expanded clay is a lightweight aggregate and concrete with such aggregate has a lower mass. But it is worth considering that expanded clay concrete screed makes sense with a thickness of 6 cm. Then the difference in weight will be about 40-60 kg per square meter. The greater the thickness, the greater the gain in weight.
Cons of expanded clay concrete:

• The price of expanded clay concrete in comparison with a cement-sand screed (CPS) is about 30% higher.
• It is more difficult to manufacture.
• More problematic when styling.

And that's not all. You will not get a perfectly flat surface. It will be fine under the tiles, but under the linoleum, laminate and other coatings, a leveling screed will be needed on top. This is additional time, and it must also be taken into account when calculating the thickness of the expanded clay concrete layer.

What is expanded clay and its types

Expanded clay is a specially fired mixture of clay and shale. There are two types of this material - expanded clay gravel and crushed stone. The gravel has a rounded and oval shape, crushed stone with sharp edges. Both materials are graded by density. It can be from 150 to 800 kg / m³, and sometimes even higher. Grades M250 (density 200-250 kg / m³) or M300 (from 250 to 300 kg / m³) are used as aggregates for concrete.

There are also different fractions (grains of different sizes):

• less than 5 mm - expanded clay sand;
• 5 - 10 mm - small;
• 10 - 20 mm - medium;
• 20 - 40/50 mm - large.

Expanded clay is added to the screed mainly of the middle fraction. It is possible and small, but it is much more expensive, and there is no strong need for fine aggregate. Large is used in a semi-dry screed.

Types of expanded clay screed and their features

There are four technologies for making a screed from expanded clay concrete:

We will not talk in detail about a dry screed - this is a separate topic. We are talking about expanded clay concrete and screed from it. All three options can be used both in the house and in the apartment. The first two are "heavier" in weight. They are also more reliable. In the sense that, subject to the technology, there are no load restrictions. The third option - with a layer of mortar over bulk expanded clay - is more problematic. It will still not work to ram the expanded clay, and situations may arise when a cavity forms under the screed layer. The top layer will, of course, sag. This can only be eliminated by redoing everything. So ... the problem. However, if the floor needs to be raised to a great height, this can be done.

Expanded clay concrete for floor screed: proportions and calculation of materials

Expanded clay concrete consists of cement, sand, expanded clay. As with any concrete, the ratio of the components depends on the required strength and on the quality of the cement. Cement is used grade M400 or higher. And it is highly desirable to be confident in quality. Sand - quarry, washed. And this is also not just that. Otherwise, the expanded clay concrete screed will have insufficient strength.

Proportions for expanded clay screed

If the composition of expanded clay concrete is known, then its proportions depend on the required strength. A screed made of expanded clay concrete for apartments and houses is not needed too high grade. M100-M150 is enough. Higher ones will be more expensive, and strength will not be in demand. To mix expanded clay concrete for floor screed, the proportions will be as follows (cement / sand / expanded clay):

• M150: 1 * 3.5 * 5.7
• M300 1 * 1.9 * 3.7

Consumption of materials per cubic meter of expanded clay concrete

Water is added depending on what type of screed you are going to do. If the classic "wet" solution, then take about the same amount of water as concrete. If they do it semi-dry, then about half of the water goes.

The peculiarity of the expanded clay concrete mixture is that the aggregate, fired clay (expanded clay), quickly absorbs moisture. Therefore, so that the solution does not dry out, you need to knead in small portions and spread immediately. Ideally, while kneading the next batch, you need to lay out / flatten the previous one. The second option is to mix the entire volume at once and smooth it until it sets.

Calculation of the amount of materials

If the expanded clay concrete screed will be made independently, you will have to purchase the materials yourself. You can calculate their number by knowing the average thickness of the screed and the area on which it will be laid. Multiplying these data, you get the volume of expanded clay concrete that you need. And by volume and brand, you can find the consumption of each of the components.

Let's take an example. Suppose that a screed made of expanded clay concrete with a thickness of 7 cm is planned on an area of ​​56 square meters. First, we translate 7 centimeters into meters: 7 cm is 0.07 meters. Next, you can search for the volume of the required expanded clay concrete: 56 sq.m. * 0.07 m = 3.92 m³. That is, it will take almost 4 cubic meters.

Expanded clay concrete: consumption of materials per cubic meter

Compositional data per cubic meter can be taken from the table above. The class of expanded clay concrete for the screed is B7.5 (grade approximately M100) or B10 (M150). According to the data from the table, 430 kg of cement, 0.8 cubic meters of expanded clay with a density of 700 kg / m³ and 420 kg of sand will be used for one cubic meter of the M150 brand. To make four cubic meters of mortar, four times more materials are needed - 1720 kg of cement, 3.2 cubic meters of expanded clay with a density of 700 kg / m³, sand 1680 kg.

As you can see, expanded clay is indicated in volumetric measure. This is because it can vary in humidity. Therefore, it is measured not in kilograms, but in cubic meters. By the way, the moisture content of expanded clay and sand must be taken into account when determining the amount of water.

Kneading by yourself or ordering?

If you are going to make a screed from expanded clay concrete in an apartment, you will have to lift it all up to the floor, and then knead it. Believe me, this is not easy at all. And then you still have to pack. Far from being a rosy prospect. Therefore, many people prefer to order a ready-made composition at the factory. You can calculate what the purchase of the material will cost you and compare with the prices that the factories are asking for. The difference is often not so big that it is worth the trouble. Of course, with a small volume - for one room - it's hard to find ready-made material. But it is already possible to order a few cubic meters.

If you need any additional characteristics (it is necessary to extend the period before setting, increase elasticity, etc.), this can be discussed. But the price will go up from this. It is also worth discussing the cost of delivery. Sometimes it is included in the price, sometimes you have to pay extra separately. Also discuss where the solution will need to be fed. The price also changes from the height.

How to pour expanded clay concrete screed (wet / liquid / regular)

There are two technologies for mixing expanded clay concrete:

Both mixing techniques are fine, just try whichever is more convenient for you. By the way, stirring with a perforator or a drill with a nozzle does not work. The load is too heavy, the equipment simply "does not pull." Even not everyone can handle a concrete mixer. Expanded clay concrete can only be pulled by "professional" concrete mixers with a powerful drive.

Training

First, we remove the base, remove debris, dust, close up large holes, remove protrusions. On the prepared cleaned base, a polyethylene film (strong and thick) is spread. Its edges should go to the walls, to the height of the screed + 5-8 cm. There they are fixed (with a bar). If one panel is not enough in width, put the second one with an overlap of at least 10-15 cm. The joint is glued with double-sided tape or coated with silicone.

The film is needed for two purposes. The first is to prevent the water contained in the concrete from leaking to the neighbors below. Even if you put in a semi-dry solution (like wet sand in consistency), there will be enough water for neighbors to have it. If there is no one from below yet - your happiness. But there is still a second function. Expanded clay absorbs water very well, and concrete needs sufficient moisture to mature. The film does not allow water to be absorbed into the ceiling, which improves the conditions for the maturation of the screed. It turns out to be of the required strength, cracks rarely appear in it.

Instead of a film, fiberglass is used (it is welded), roofing material, and other waterproofing materials. Fiberglass improves sound insulation a little, roofing material may seem more reliable. You can use other materials, of which there are many now. You just need to take into account their compatibility with concrete. What not to do is hope for impregnation, even if it is a deep penetration impregnation. It will reduce water absorption, but it will not become zero. And, most likely, the neighbors below will still have water.

Beacons are placed on top of the waterproofing - the expanded clay concrete screed is leveled along them. If it is planned to lay another DSP on top, the beacons are set taking into account the DSP, and expanded clay is leveled "by eye". You can make a template equal in height to the planned screed, but taking into account the thickness of the beacon. That is, the thickness of the beacon + the width of the plank = the planned thickness of the DSP. With such a template, it will be possible to level the expanded clay concrete by drawing a bar under the lighthouse strips and using them as a basis.

Laying and leveling

They begin to lay out the surface from the corner farthest from the entrance, gradually moving towards the exit. Plan the fill so that the passage by the door remains clear to the last. You can make a strip to the left - from the wall to the door, then to the right - also to the door. Then fill in the middle, move towards the exit.

It makes sense to level it thoroughly only if you will not make a leveling layer on top. We must, of course, try to align, but the ideal will still not work. For a slurry, there is, by the way, a very good trick - the vibration of concrete when laying. There are special devices that can be rented. The submersible vibrator creates vibrations that remove air bubbles, the concrete becomes, as it were, more fluid, fills voids and cavities that cannot be filled in any other way. In the case of expanded clay concrete, this is especially true, since air bubbles appear in larger quantities than in ordinary (heavy) concrete. With such processing, by the way, it evens itself out, the drops are eliminated. But this only works if the concrete is laid out quickly. Laying in pieces does not have this effect.

Care before ripening

After pouring, expanded clay screed needs to retain moisture. As already mentioned, expanded clay quickly absorbs moisture, and cement needs moisture to gain strength. So, so that it does not evaporate, the surface is covered with a film. On the second day, the screed can / should be spilled with water. Puddles should not stand, but the surface should darken significantly. Within a day, the concrete will become dense enough to be walked on, and you can water it from a watering can.

The film is kept for about a week, then it can be removed. During this time, at a temperature not lower than 17 ° C, the screed will gain 50% strength. You can further lay the tiles or fill in the leveling layer, lay out the DSP.

Features of a semi-dry expanded clay screed

Semi-dry expanded clay screed differs only in laying. A semi-dry solution does not flow - it is like wet sand in consistency. Approximately the same when there is no more water, but it has not yet dried up. You can sculpt figures from it. This composition is laid in small sections - so that you can reach the edge with your hand. It is stacked, leveled and rammed. To increase plasticity, dishwashing detergent is added to the solution. We need it quite a bit - a couple of drops on a bucket of cement. It is the cheapest supplement and makes styling much easier.

A semi-dry expanded clay screed is pre-leveled with a rake, then it must be compacted. For leveling, you can use the rule, and then smooth it with a tamper. Having tamped, the rule is used to cut off excess height. He is pressed against the guides and pulled towards himself. If there are pits, they are filled, compacted, and again leveled with the rule. So until you get a flat surface.

We pay special attention to the joints of the laying zones - here we ram especially carefully. We try to ensure that the next piece is laid before the edge starts to set. If this does happen, it is better to coat with a primer.

Expanded clay screed

A screed made of a cement-sand mixture, on bulk expanded clay, is done if the floor needs to be raised to a significant height - 9 cm and higher. The large and medium fraction of expanded clay is distributed evenly, roughly leveled. Then it is spilled with cement diluted with water (cement milk). It is necessary to moisten the outer layer. There is no need to spill to the ground. This step is necessary so that the poured expanded clay "seizes" and is a normal basis for moving. This step has no other function.

After leveling the expanded clay, boards are laid on it - you can walk on them and water the expanded clay. Every other day, you can put beacons and pour or lay DSP. Plain or semi-dry. Thickness - not less than 3 cm, higher grade - M200 at least. To increase reliability and redistribute loads, it is not superfluous to lay a reinforcing mesh, and mix reinforcing additives (fiber) into the solution. We take a metal mesh with a pitch of 50 * 50 mm. We pull the grids together so that they transfer loads to one another. In this type of screed, it will not be superfluous.

Leveling layer

As already mentioned, the expanded clay concrete screed does not give a flat surface. Rather, a fairly flat surface can be made by craftsmen who are engaged in this particular type of screeds. And that's not all. Therefore, it is usually advised to put a layer of mortar on top or pour a self-leveling mixture (on a cement basis, not on a gypsum base).

With DSP everything is clear, but about leveling mixtures there are several points about laying.

A few more points. When pouring the leveling agent, it is better to move around in shoes with spiked soles. Of course, no one will buy it specifically, but you can make something similar from scrap materials (boards with screws). More. It makes no sense to align with beacons with the rule. It will be worse than with a roller. As a rule, you can disperse at the beginning when the entire composition has been poured. It's easier to distribute it this way. Then "roll" with a needle roller.

What to do if the expanded clay concrete screed cracks

Cracks in the screed, even small ones, are not good. They appear due to violations of technology, low-quality components. Another possible reason is the drying out of the screed, in which its dimensions decrease (on average, shrinkage is 1 mm per 1 meter). But in order to prevent cracks from appearing, they are laid along the perimeter of the premises. It also reduces the level of noise transmitted through the floors. That is, the impacts will not be so audible in the apartment, and other noises will not be so loud.

If cracks do appear, they must be repaired, even if it is planned to pour leveler on top or lay tiles. If left as is, chances are high that the top layer will also develop cracks in the same place. Even if everything is done perfectly. The emptiness at the bottom creates the prerequisites for the formation of cracks, so they must be repaired.

So, the cracks are embroidered, cleaned out as far as possible. Dust is removed, and then poured with a repair compound for concrete floors or epoxy glue. Cracks can be moistened under the repair composition; this should not be done under epoxy. That's all. The expanded clay screed is ready, you can lay the floor covering.

Even before erecting a building, you should think about how the future floors will look like. In order for the finishing finish to lay down with high quality and serve for a long time, a perfectly flat and strong screed should be equipped under it. Among the analogues, one of the most progressive screed options is expanded clay concrete. As the name implies, expanded clay serves as its main component. This is the name of a special granular mixture obtained from fired clay. It is precisely the granular consistency that is made possible by the foaming of the clay.

What is it for

This type of screed significantly improves the noise and thermal insulation of the room. Most often, the used sand-cement screeds are significantly inferior to expanded clay in these parameters. In addition, any flaws in the coating when using this leveling method can be easily corrected. The light weight of the mixture makes it possible to save money on its transportation. Often used when there is a need to raise the floor level. At the same time, the frozen solution has a high strength, does not allow moisture to seep out.

Pros and cons of expanded clay concrete mixture

Like any other material, the use of such a mixture for floor screed has both negative and positive aspects. It owes its main advantages to the natural properties of clay and its firing.

Advantages of expanded clay concrete screed:

• Differs in fire resistance and water resistance;
• Does not rot;
• Does not rust;
• Durable;
• It is lightweight;
• Helps create a high level of heat and sound insulation;
• Safe for humans and the environment.

After analyzing the above advantages, the conclusion that this type of screed is an ideal basis for any type of floor finish is obvious.

But nevertheless, it also has its negative sides:

• This type of screed cannot be made thin;
• To achieve perfect smoothness, it needs additional procedures, namely, grinding.

Expanded clay concrete screed allows you to correct even large floor errors. Moreover, it will not be difficult to do it yourself. A similar screed is also suitable for creating sloped floors. It is used for leveling the floor, both inside and outside residential and industrial premises.

Gallery

Preparation of the solution

The composition of the solution may differ depending on the type of premises in which it is used. For public and industrial buildings, a cement-sand mixture with expanded clay is combined in a ratio of 3: 2.5.

When performing work in a residential area, the dosage changes somewhat, cement, sand and expanded clay are taken, their proportion is as follows: 1: 3: 4.

To obtain a high-quality solution, it is necessary to observe the technology for its preparation:

• Expanded clay is poured into a special container, or better a construction mixer.
• Water is added so that the level is two fingers above the level of the clay pellets. Due to its porous consistency, expanded clay will not take in a lot of liquid. With a construction mixer, the moisture absorption process is much faster than with manual mixing.
• When the moisture is completely absorbed, without stopping the batch, the cement-sand mixture is poured.
• Since there are no clearly regulated dosages, the state of the mixture should be constantly monitored. Pouring cement with sand is stopped when expanded clay becomes gray.

Video

Tools and materials required

To perform a set of works on leveling the floor surface, you will need some materials and tools:

• To remove the previous shavings, you will need a hammer drill;
• Several steel spatulas of different sizes;
• Roller;
• A set of trowels;
• Capacity for batch preparation;
• Rule;
• Plasterboard mounting profiles;
• Capacity with water;
• Paint brush;
• Hydro level;
• Shovel;
• Devices ensuring the safety of the respiratory and vision organs: mask, goggles;
• Gloves.

To prepare the mixture, you can take a ready-made solution, but this is not at all necessary. By making your own screed mixture, you can significantly save on its ingredients. The main thing is to correctly observe the necessary proportions. You will need:

• Cement brand M400;
• River or washed quarry sand;
• Expanded clay;
• High penetration primer;
• Silicone sealant;
• Finishing filler for leveling.

Keep in mind that the room where the floor leveling work will be performed will be very dusty. Remember to protect items that could be damaged by wrapping them in plastic wrap.

How to make expanded clay concrete screed

Preparatory stage

Before you start mixing the solution, you must carefully prepare the surface of the subfloor. These actions are performed approximately in the following sequence:

• The room is freed up to the maximum, furniture is taken out, hanging elements are dismantled;
• The previous floor covering is dismantled together with the skirting boards;
• The old concrete screed is removed;
• All large construction debris is taken out of the room, and the dust is removed with a vacuum cleaner;
• If there are cracks, they must be treated with a primer and a cement mixture;
• Casing holes are cleaned through which pipes and communications are laid;
• The holes are cleaned, filled with heat-resistant sealant and putty;
• Base slabs and walls are primed twice. This effect gives the subfloor hydrophobic properties, thanks to which water will not be able to penetrate the floor slab.

All subsequent work begins after the primer layer has completely dried. This usually takes up to five days. After that, you can start marking work.

Installing beacons

In order for the prepared solution to lay down evenly, without errors, it is necessary to mark the level of the horizon of the future floor.

Using the hydro level, we determine the highest point in the room. Beacons will be placed based on this mark.

Installation of beacons is carried out using metal profiles for drywall. They are fixed to the subfloor with cement mortar. The distance between the beacons should not be about 1 meter. After fixing the last profile-beacon, the correctness of setting their level is once again checked. In case of any inaccuracies, the beacons must be rewired.

We fall asleep expanded clay

Expanded clay granules are poured into the space between the rows of beacons and carefully leveled. At the same time, it is impossible for the level of the backfill to rise above the profiles, but, on the contrary, be lower than them by at least 3 cm. After that, we fill it with the so-called cement milk and tamp this layer.

We carry out the fill

This process begins only after the surface is completely dry. It is carried out with a cement mixture. A smooth surface is achieved using a rule and a building level.

Removing beacons

After the screed dries up, the beacons can be dismantled. This usually happens after 1-2 days. The resulting seam is filled with cement mortar, rubbed over with a float.

Drying the screed

Complete drying of the expanded clay concrete screed occurs after 14 days.

Outcomes

The quality of the finished solution depends not only on the correct proportions, but also on the brand of materials used, strict adherence to all recommendations for pouring and drying the solution.

During operation, depending on the intended purpose, a number of technical requirements are imposed on the floors of buildings and structures. These are strength, evenness, maximum specific load, degree of thermal insulation, and so on.

General description of expanded clay concrete

An excellent option in terms of price, quality and speed of installation of the floor surface is the laying of a concrete screed, which ensures perfect evenness and high wear resistance. However, this type of floor has a number of disadvantages - a high specific weight per unit area and a low degree of thermal insulation along the entire depth of the surface. Expanded clay concrete screed, which is a lightweight concrete, retains the advantages of a conventional concrete screed, but at the same time is devoid of its disadvantages.

The method of obtaining expanded clay concrete for floor screed is simple and differs from the classic concrete solution, consisting of cement, sand, water and crushed stone, only in that expanded clay is used instead of crushed stone. It has the form of gravel with a porous structure in the form of an oval of various fractions from 5 to 40 mm, it is produced industrially, by firing clay or its derivatives. The variability is determined by the type of construction work carried out. The smallest one is used for the production of expanded clay concrete screed and the production of blocks, the medium one is used for bulk insulation of floors and ceilings, the large one is used for thermal insulation of outbuildings and heating mains.

Types and area of ​​application of expanded clay concrete

The classification of expanded clay concrete is quite extensive and depends on the requirements for the type of products produced, granule density, application and solidity. All these features are standardized by the brand (for example, expanded clay concrete M100), which determines the class of its application and varies from 35 to 100 kg / cm²:

Expanded clay concrete grade	Application area
	arrangement of supporting structures, erection of partitions inside the premises
	erection of load-bearing structures in the construction of residential and industrial buildings
	floor screed
	production of expanded clay concrete blocks
	And floor slabs
	installation of engineering structures with high periodic load

Taking into account the field of application, the density of expanded clay concrete serves as an important characteristic, which is determined by the ratio of mass to volume of the material and has a range from 700 to 1400 kg / cm². Often, in buildings of an old and not very old construction, for a number of reasons (subsidence of the foundation, unskilled installation), there are significant differences in the floor level of adjacent rooms, and sometimes even inside the same room. Leveling to a single level by means of a conventional cement-sand screed can seriously increase the load on the load-bearing elements of the building, which is highly undesirable, especially when it comes to multi-storey buildings.

Due to the porosity of the screed, it is significantly less than the density of heavy concrete, which determines the absolute priority of its use in such a situation. An increase in the percentage of cement in expanded clay concrete increases the strength of the structure, however, there is a significant increase (up to 1.5 times) in the weight of concrete. Accordingly, the maximum possible reduction in the cement component of the material allows you to reduce its bulk density. In this regard, the grade of Portland cement used in its production must be at least 400.

Advantages of using expanded clay concrete

And it does not sink in water, and does not burn in fire. Low thermal conductivity determines the high heat resistance of expanded clay concrete, which means long-term resistance of the material to high temperatures. Even at temperatures above 1000 ° C, expanded clay concrete retains its mechanical properties. The material shows itself very well when exposed to moisture. Unlike stones, which, after being saturated with water in frost, are destroyed, expanded clay concrete has high frost resistance, that is, the ability to freeze and thaw many times without losing strength.

Another important factor that determines the priority choice of expanded clay as a filler for concrete is its environmental friendliness. It does not emit harmful substances either when exposed to an aggressive environment, or over time, or with complete destruction. This explains its choice as a building material and insulation in living quarters.

Preparation of the base for pouring the floor with expanded clay concrete

If the screed is made on top of an existing even and dense coating, then this stage of work can be skipped. However, most often, pouring is performed directly on the ground, in this case additional preparation of the base is required. The surface is leveled and carefully compacted, the pits are covered with sand, the protrusions are knocked down for uniform laying of the pillow. The pillow is a layer of sand about 2-3 cm and a layer of expanded clay or crushed stone 3-5 cm thick, as much as possible, up to the level of the rough base. Next, a plastic film or roofing material is laid to waterproof the future screed, a masonry mesh is mounted and beacons are installed.

Types and methods of using expanded clay screeds

Having dealt with the basic properties and technical characteristics of expanded clay concrete, its pros and cons, we will try to understand how to properly fill the floor using this material. The choice of the type of expanded clay concrete screed depends on the type of base on which it is made, and therefore floor screeds can be of three types. Let's consider each of them.

Dry screed

Expanded clay gravel is evenly and without distributed over the previously prepared, cleaned and compacted surface of the base, not reaching 2 cm to the lower level of the lighthouse. in this case it is determined by the required degree of thermal insulation. Next, the entire area is poured with cement milk, which is made by mixing cement with a large amount of water without adding sand. This procedure will fix the expanded clay and cover the gravel with a thin protective layer that prevents moisture from drawing out of the finishing screed, which will give additional strength to the floor. After that, the usual thin screed is performed. The advantages of this method are the speed of installation, the disadvantages are low surface strength.

Wet screed

With this option, so much water is added to the solution so that the light and porous expanded clay, after pouring the screed, floats to the surface. Concrete hardening takes a little longer, all the filler is concentrated at the top of the screed. The advantages include self-leveling of the mixture. The disadvantages are long drying, the need for special preparation of the surface to be coated in order to avoid leaks, as well as the implementation of the subsequent surface screed, if necessary, to obtain a smooth surface. In this way, attics and outbuildings are usually insulated.

Semi-dry screed

The most common type of expanded clay concrete pavement, which is identical in manufacturing method to ordinary concrete. For the correct filling of the floor in this way, expanded clay concrete M100 is used. In its manufacture, they take expanded clay of the first fraction with a diameter of 5-10 mm. The proportions of the mixture are as follows: 1 part of Portland cement grade 400 - 3 parts of sand - 4 parts of expanded clay. As for the amount of water, this parameter must be selected individually, depending on the moisture content of the sand. It is necessary to achieve a consistency in which the granules of the material would not float to the surface, which makes smoothing difficult, at the same time, the solution should not be too dry, as this complicates its installation and can lead to the formation of voids and cracks in the screed mass.

The solution is mixed in a concrete mixer or in a large container. The use of a mixer nozzle is extremely problematic due to small portions in one batch, and this makes the installation long, the solution turns out to be of different consistency, and expanded clay is distributed unevenly in the mass of concrete. The sequence of mixing the ingredients in different sources is described differently, but in practice it does not matter in principle. The main thing is that the solution is uniform and the expanded clay granules are completely covered with a binder.

The solution is applied in an even layer over the entire surface to be coated, while it is necessary to comply with the condition - the thickness of the expanded clay concrete floor screed must be at least 3 cm, usually it is 4-6 cm.If the correct consistency of the solution is chosen, the surface will turn out to be perfectly flat and all that remains is to produce grout it one day after laying. The advantages of this method of covering are obvious - the possibility of using it for all types of floors and ceilings. The disadvantage is the high labor intensity, filling with the use of beacons and the need for finishing grouting.