Weight of semi-dry screed per 1m2

Often new buildings are delivered with rough repairs and on the floor we see floor slabs with broken heating pipes. The whole thing is covered with a floor screed: classic (concrete mixture) or semi-dry (using a relatively new technology). But few fully understand what it is.

Composition of semi-dry solution

The basis of the semi-dry mortar is sand, cement and water.
This is the base from which floor leveling can be done in many cases. Fiber fiber, various additives and plasticizers are not primary in the composition. Their absence in certain cases is not critical. And, to be honest, you shouldn’t bother yourself with them. Imagine - an ordinary screed in ordinary new buildings - what kind of fiber? - maximum plasticizer (not a fact). And will this make the screed worse for ordinary household use? Of course not. Another issue is the additional financial costs and the need for use. If you can afford it, then using additional components is somewhat acceptable. And only in those cases where it is necessary. Let's look at the main (and not so basic) components that make up a semi-dry floor screed:

The basis of the foundation is cement. The brand of cement is not so important. The main thing is to maintain the proportions for a specific brand of solution. The higher the grade of cement, the less it will be required in volumetric terms.
Sand without impurities. To prepare construction powder, quartz, river or construction sand with a fraction of no more than 3 mm can be used. Sand of larger fractions is not desirable with the semi-dry method.
Water.
Fiber fiber. Polypropylene fiber acts as a reinforcing mesh, which gives the layer special strength and resistance to mechanical stress. The use of additional components has already been mentioned above. However, I would like to once again dwell on the absurdity of some information, which, unfortunately, is at the top and publicly available. Here is one of the gems: “But, unlike a metal frame, fiberglass is not subject to corrosion and destruction.” Essentially, high-quality (non-rusted reinforcement) placed in mortar or concrete, if used correctly, will outlive the great-grandchildren of the “great” construction experts.
Plasticizer for semi-dry floor screed. Plasticizers are modifiers for concrete and mortar mixtures designed to increase the fluidity and workability of the mixture. As a rule, these additives are used to reduce the water-cement ratio, as well as for self-compaction of concrete and mortar mixtures.

Specific and volumetric weight of concrete in 1m3, table of weights of all brands.

Concrete is the main component of any construction work, be it ordinary repairs or the construction of pits and structures. It has high strength initially, but with the use of additives it can improve its characteristics.

During construction, first of all, how much concrete weighs is calculated, since based on this characteristic it is determined by the specifics of its use and application. The weight of the solution depends directly on the components added as filling. These can be materials such as crushed stone, expanded clay, pebbles and many others.

Also, when kneading, the volume of water spent is taken into account. Based on these characteristics, concrete is divided into four types: light and heavy, especially light and especially heavy.

Weight of 1 cube of concrete of all brands and classes, table:

Types of specific gravity of 1 cube of concrete.

The most common way to classify the mass of a cube of composition is by dividing it according to specific gravity.

According to the volumetric mass, the following types of concrete are distinguished:

Particularly light: Weight 500 kg maximum per cubic meter. Characterized by the content of air cells with a diameter of 1-1.5 mm and a porous base. These are the familiar foam and gas blocks, which are based not only on classic cement and sand, but also on a foaming agent that creates cells with air. This allows for low weight and good thermal insulation properties.
Lightweight - concrete compositions filled with lightweight porous aggregates, such as expanded clay or without aggregates, but having a porous structure, such as foam concrete or aerated concrete. A cube (cubic meter) of lightweight concrete weighs from 500 to 1800 kg. A cubic meter of concrete includes about 600 kg of sand - the main and essential component. Lightweight concrete is usually used in the form of ready-made building blocks.
Heavy. This is the most common (classic) type of mortar. It is best suited for the construction of the main elements of load-bearing structures, pouring screeds, erecting fences, etc. The composition of heavy concrete includes large-sized and massive fillers: coarse sand, gravel, crushed stone. They occupy the bulk of the mixture. A cubic meter of such material weighs 1800-2500 kg.
Particularly heavy . Metal fillers are used in production, giving the finished product a massive appearance. The weight of a cube of concrete is 2500-3000 kg. Super-heavy mixtures necessarily contain high-strength cement. They are not used in private housing construction. They are usually used to make protective structures for special purposes, for example, for nuclear reactors.

Calculation of the amount of material and proportions

There are two types of mixtures used in construction: regular and ready-made. Conventional mortar is used to level not only the floor, but also to level the walls. The simplest standard solution of self-leveling floor screed is prepared using M300 grade cement and clean sand, which has a medium-grained fraction. The third component is water.

All components are mixed as follows: take 1 part of cement and add 1.5 - 3 parts of medium-grained sand. But the amount of water is calculated based on how many kilograms of cement were taken. For 1 kg of cement take 0.5 liters of water.

Now on the construction market there are a lot of modifiers and fillers that are added to the sand-cement mixture. Why do they do this? To increase frost resistance, reduce the time for hardening, and also reduce the likelihood of cracks and delamination.

Conventional mortars, like backfill for dry floors, are sold on construction markets. Their use will reduce the time spent on repairs. In such mixtures, all components are ideally selected and in ideal proportions. The manufacturer produces each type for one or another type of connection to the floor.

The video shows the consumption of PCB per 1 m2 of screed:

The weight depends on the proportion of the components that are included in the composition: on the amount of water, on the power of the screed and on the brand of cement used. The maximum thickness of the screed usually does not exceed 7 cm, otherwise the foundation of the house will have to be strengthened so that it can withstand such a large load. Depending on the thickness of the layer, choose the type of bond:

the screed will be connected to the rough foundation and to the walls;
will not be associated with any structures;
an insulating layer is used, as a result it will be a floating layer.

Rules for installing DSP

Whatever the weight of the resulting cement-sand screed per 1 m2, the work process does not change. The list of preliminary works is voluminous:

setting guidelines - will help not to exceed the required height;
moistening the surface - the subfloor needs to be thoroughly moistened for better interaction with the mixture;
reinforcement is not mandatory.

Filling the floor according to beacons
Before carrying out any work, tap the subfloor. Fill the broken pieces of concrete and opened voids with mortar and allow to dry. It is recommended to use a special primer that will increase adhesion to the DSP.

For convenience, use laser levels when marking. They are guaranteed to give accurate results.

When preparing a dry mixture, mix the ingredients until the consistency resembles a cream.

Ready mix

The prepared solution should be poured 1 cm above the mark. This is explained by the fact that compaction will follow - to eliminate excess air. Afterwards the mass will settle and be level with the mark.

To be safe, make adjustments using a level.

The last stage is the elimination of landmarks and traces of them.

The drying speed directly depends on the characteristics of the mixture, however, specialized products can also be used. They speed up drying, but may have a negative effect on other additives. Make sure that the selected additives are compatible before mixing. Look for the necessary information on the official websites of manufacturers or professional construction resources.

Classification of screeds.

According to the method of adhesion to the floor, there are the following *types and types of screeds*:

Related to the base;
On the separating layer;
On an insulating layer (“floating”).

Rice. 1. Types of screeds according to the method of adhesion to the floor

Tied ties are those that are tightly coupled to the base. In other words, there are no separating layers between the base and the screed. This type of screed can withstand heavy loads, but the shrinkage of tied screeds is uneven and can often result in cracks. And the humidity of such screeds depends on how saturated the ceiling is with moisture. The use of screeds on the separating layer will help prevent the screed from adhesion to the ceiling. The role of the separating layer is usually performed by the following materials:

Bituminous paper;
Oiled paper (glassine, roofing felt);
Polyethylene films.

In order for such a screed to be strong enough, its thickness should be at least 30 mm. If special waterproofing is required, then a screed is applied to the separating layer.

“Floating” screeds on the insulating layer are not connected to the base. This is an independent building structure. The layer - bedding between the floor concrete and the “floating” screed is made of the following heat and sound insulating materials:

Stone wool;
Mineral wool;
Foamed polystyrene;
Cork board;
Fiberboard.

The smallest thickness of a “floating” screed is 50 mm. The use of screed on the insulating layer increases the thermal and sound insulation of the floor. In addition, the moisture contained in the screed will not depend in any way on the concrete floor. But this design scheme has low compressive strength and also has increased thickness. In this type of screed, in most cases it is necessary to additionally reinforce the top layer.

Rice. 2. Reinforced screed

Prefabricated screeds are elements that are ready for installation and are designed to be connected with seams. Installation is made from large-sized sheets, as well as slabs - plywood, chipboard, fiberboard, gypsum fiber (GVL) sheets. The elements of prefabricated screeds are not heavy, so even one person can easily install them. There are no “wet” processes when working with prefabricated screeds, which makes it possible to lay face coverings immediately after installation. It should be noted that prefabricated screeds cannot be used for every face covering.

Rice. 3. Dry screed diagram

Separation of concrete by specific gravity.

The classification of concrete includes 4 groups with a weight range of 1 m3 of mixture:

1. Extra light – up to 500 kg.

They are also called cellular concrete; they do not contain large fillers. This solution consists of sand and concrete, and a foaming agent is added to it. Air pores form inside the solution (the volume of which is 85%). Lightweight concrete has a very low specific gravity: less than 500 kg. This group is most often used in the production of blocks and slabs, which serve as insulation materials in structures. Online calculation of the composition of cement mortar.

2. Light – 500-1800 kg.

For this type of concrete, various porous materials are used as fillers: foamed perlite, expanded clay, waste from various industries, vermiculite. The weight of concrete is reduced due to the porosity of the material, which is why it is called light.

The weight of 1 m3 of this species ranges from 500 to 1800 kg. Sand is not used in all types of lightweight concrete, but if it must be available according to the recipe, then its mass in 1 m 3 is about 600 kg. Lightweight concrete mortars are used when pouring fences, screeds, and block products.

3. Heavy - 1800-2500 kg.

This group of concrete solutions contains heavy and coarse fillers (coarse sand, gravel, crushed stone). The weight of 1 m 3 ranges from 1800 to 2500 kg. The recipe for heavy concrete shows that it is the fillers that occupy the bulk of the mixture.

The standard recipe consists of: crushed stone or gravel - 1200-1300 kg, sand - 600-700 kg, cement - 250-450 kg, water volume - 150-200 l.

This type of concrete is considered classic (traditional), they are widely used in various construction works, for example, pouring screeds, load-bearing structures, fences.

4. Particularly heavy – 2500-3000 kg.

This type of concrete is not used in the construction of private housing construction; most often they are used in nuclear reactors as a protective structure. The mass of 1 m 3 in such concrete ranges from 2500 to 3000 kg. The bulk of them is occupied by large aggregates.

Varieties: cement screed

Messenger
. Typically used in high-rise buildings - the DSP here serves to level the floor slabs. To create a reliable base, you need good adhesion - connection - between the poured layer and the old one. That’s why the type of screed is called – connected. Its minimum layer is 3 cm.
Incoherent
. With this type of base, the new layer is not bonded to the old floor. For example, installation on a concrete base that has been previously polished or on a layer of insulating material. The minimum thickness of the screed is 5 cm.
Floating
. If the floor needs to be made warm, it is impossible to achieve a rigid adhesion of the screed to the base. When the insulating material changes its dimensions, the concrete layer placed above also lowers/raises. That’s why this screed is called floating. To create rigidity, which requires a minimum thickness of the cement-sand mass in this version of the screed, at least 6.5 cm.

All of these types of CPS have their own installation characteristics, but they are united by the use of sand-cement mortars. Sometimes, to increase reliability, reinforced fibers are added to the composition. This is usually fiberglass; there are additives from small parts of steel wire, but they are not used often. Reinforcement of the solution is required when the concrete layer is large.

According to building rules, the minimum thickness of the screed is 3 cm. With the thinnest layer during the period when the mortar dries, the canvas will crack and the base will be unreliable. At the same time, concrete has a lot of weight: per 1 m2, a 10 mm layer weighs approximately 20 kg. And since the minimum thickness is 3 cm, then the minimum weight of 1 m2 of screed will be 60 kilos. Not every foundation is capable of supporting such a load without consequences. This can cause the foundation to shrink and crack. To reduce the weight of the screed, light binders, for example, expanded clay, are included in the solution. The mass of 1 cm of expanded clay concrete is 16 kilos. With volumetric footage being poured, the difference is significant.

Separation of concrete by specific gravity.

The classification of concrete includes 4 groups with a weight range of 1 m3 of mixture:

1. Extra light – up to 500 kg.

2. Light – 500-1800 kg.

3. Heavy - 1800-2500 kg.

Mixture preparation and consumption

To obtain a mortar for grade 150 screed, you need to mix cement (M400) with clean, washed and sifted sand without foreign inclusions (usually clay) in a ratio of 1:3, in other words, for 1 shovel of cement and 3 shovels of sand. These proportions are always indicated on the packaging of a specific brand of cement. If necessary, plasticizers and other additives are added. The resulting mixture is thoroughly mixed and adjusted with water to the required consistency.

Semi-dry screed technology eliminates shrinkage, deformation, and the appearance of cracks. To visually check the compliance of the technology, the prepared solution can be squeezed tightly in your hand and not a drop of water should come out of it.

When adding fiber, the following proportion must be observed: per 1 cubic meter of solution there should be at least 600 grams of polypropylene fiber.

In the question of screed consumption and calculation of the necessary components, we turn to the table of cement consumption per cubic meter of solution:

Maka cement	Brand of solution	Cement consumption per 1 m³ of solution
M400	M200	490 kg.
M500	M200	410 kg.
M400	M150	400 kg.
M500	M150	330 kg.

Let's calculate the required composition of semi-dry screed for a room with an area of 20 square meters. We will use cement (M500). The cement/sand proportion for mortar grade 150 is 1/4, respectively. The thickness of the screed is 4 cm or 0.04 m (minimum permissible value).

Calculation:

20 (sq.m.) * 0.04 (m.) = 0.8 cubic meters of mixture is required.
From the table above, the consumption of cement (M500) per cubic meter of solution (M150) is 330 kg.
We make up the proportion: x/0.8 = 330/1; where x is the required cement consumption for a volume of 0.8 cubic meters. mixtures. Accordingly, the required amount of cement (x) = 330 * 0.8 = 264 kg.
Based on the proportion of 1/4, sand will be required - 264 * 4 = 1056 kg.

This calculation will allow you to calculate with a certain degree of accuracy all the components that you will need for the screed.

How much does a cube of concrete weigh - weight table for all brands!

Often, when planning construction work, you need to know how much a cube of concrete weighs m300, m400, m500. Let's see how much a cubic meter of concrete mixture will weigh, depending on its type. The mass of the concrete mixture is determined by the mass of the aggregates used.

Weight m3 of concrete grades M100, M200, M300, M400, M500.

According to the specific gravity, the concrete mixture can be:

especially light up to 500 kg;
light 1000 to 1800 kg;
heavy 1800 - 2500 kg;
especially heavy 2500 to 3000 kg.

As you can see, there is nothing complicated when calculating the mass of concrete mortar, and then we will consider in more detail the question of what the mass of concrete is for different brands, and we will also provide a detailed table.

Advantages and disadvantages of semi-dry screed

The choice in favor of this technology is justified by a number of its advantages, which did not go unnoticed by builders of all levels.

Semi-dry screed has the following advantages:

A small amount of water added to the mixture. Its penetration into the ceiling is almost completely eliminated. A reduction in the weight of the poured material is achieved.
Reduced setting and complete drying time. Ability to continue working without a long break.
Creating a perfectly flat surface at the formation stage without the use of self-leveling solutions and additional leveling.
Minimizing the likelihood of cracks and shrinkage after curing of the solution. No risk of internal voids forming.

This method also has disadvantages:

Impossibility to do without special equipment. It is necessary at the stages of preparation, distribution and compaction of the mixture.
Difficulty filling internal corners. You have to spend time and effort on this, sealing such places manually.
Restriction on the minimum thickness of the slab. It is 30 mm, provided compaction is carried out with a powerful pneumatic spreader.
Fast setting. On the one hand, this is a plus, and on the other, a minus, since the solution can harden without sticking to the base.

Handmade cement floor screed in a bathhouse

To level the floor slabs, use a tie screed. In apartment premises, the floors between floors are usually made of reinforced concrete slabs. This sand-cement screed is also suitable for a bathhouse building on a slab foundation. But only when waterproofing and insulation are not needed.

This type of screed is also suitable for

Porches;
Tambura;
Verandas, etc.

The main task of preparation in this case is to create the best possible adhesion of the concrete layer to the base. To do this, you need to very well clean the surface of debris and dust. It is better to do this by using a vacuum cleaner - a brush cannot remove all the dust. There is no need to level out uneven areas; on the contrary, if there are smooth areas, it is necessary to make grooves/pits in them. Correctly seal only very deep cracks, and do not even out the surface. After all dirt has been removed, the surface is generously primed.

The primer must be allowed to dry for at least 8 hours; drying time depends on the humidity and temperature conditions in the room. After drying, you can install the beacons and pour the mixture (cement, sand) with your own hands. In order to prevent the destruction of the screed or vertical surfaces due to different amounts of expansion when changing temperature conditions (different densities), a damper tape must be installed around the perimeter of the room. This especially plays a role when the vertical surfaces are wood, which is almost the rule in bathhouses.

The tape must be rolled out and attached to the walls. It is usually larger in height than the screed, but when the cement sets, it must be cut to the level of the floor. If waterproofing of the DSP is required, it will no longer be cohesive. Here the preparation is different. Waterproofing material is placed on a clean and flat surface. If the base is uneven, for example, the surface of the foundation slabs in a bathhouse, then it must be leveled. For this purpose, the leveling connection DSP described above is used.

After drying it, you need to lay out the waterproofing and pour another layer of concrete (a special tape will also be required). Due to the fact that the base does not absorb moisture during such installation, cavities and pores may appear. Therefore, the solution must be processed with a vibrator. By increasing the thickness of the floor surface screed to 100 mm, the problem resolves itself, but the costs and weight are greater.

It is important that the filling technology is followed

Types of concrete screed

With reinforcing mesh

Concrete screed is used most often. To construct it, a metal mesh is used, which is covered with 4-5 cm cells. Low supports are installed throughout the floor and the mesh is laid on them. This increases strength and wear resistance. Among the disadvantages of use it should be noted:

due to the metal's susceptibility to corrosion, the mesh will gradually deteriorate, the concrete screed may delaminate, which adversely affects the service properties. This process takes many years, so the prevalence of the method has not decreased;
cracks may form.

Fiber screed

Due to the constant development of construction technologies, fiberglass has recently begun to be used in laying concrete screeds. It is placed in a concrete solution instead of a reinforced mesh. It is a thin synthetic substance - microfiber made from polymer granules.

By making concrete more flexible, fiber fiber adds resistance to cracks. The advantage is that the use of such material is easier and more economical than metal mesh by 6 times per m2. In addition, do not forget about such a plus as the effect of reinforcement. The disadvantages include strict adherence to proportions and calculations when using the material. A mistake will turn the concrete into crumbs.

Features of working with different types of screeds.

Different types and types of screeds imply individual characteristics of their installation.

Manufacturers of screeds indicate the degree of strength of the coating in the instructions for their products. But the manufacturer does not do the installation itself, so the warranty only applies to the material. As a result, the packaging often overstates the strength of the original screed. There is a conflict of interest. The manufacturer is interested in having the material he produces laid on a super-hard screed; the buyer wants to buy a quality product at an affordable price. If the buyer fulfills the requirements of the flooring manufacturer and makes the screed with a strength of up to 300–400 kg/cm², he will retain the warranty. If he does everything according to the requirements of SNiP, then he can be sure that everything was done correctly and reliably. The conditions of SNiP 2.03.13-88 “Floors” are as follows:

1) The strength of the screed based on cement binder for all types of floor coverings should not be less than 150 kg/cm²;

2) If it is necessary to level the screed with self-leveling mixtures - at least 200 kg/cm²;

3) The strength of gypsum screed for all types of floor coverings should not be lower than 100 kg/cm²;

4) For polymer “self-leveling” - no less than 200 kg/cm².

The screed for self-leveling mixtures is usually made the strongest, because the “self-leveling” mixture sets the fastest, which contributes to the development of high internal stress. There will be no cracks, but a weak bottom tie may be “pulled” and torn from the base.

You also need to take into account that a complete replacement or installation of a new screed will put all its weight on the reinforced concrete floor slabs. Reinforced concrete floors in old houses have limitations on load-bearing capacity, which is equal to 400 kg/m² - permanent load and plus 150 kg/m² - temporary load. For example, every centimeter of a screed with a volumetric weight of 1800 kg/m³ will press on the ceiling with a weight of 18 kg/m². If the screed is 5 cm thick, then each square meter of flooring will receive a load of 90 kg. These figures prove that such a screed will take 25% of the entire load-bearing capacity of the floor.

If it is necessary to increase the thickness of the screed or replace the screed material with one that is heavier, everything will have to be coordinated with the load-bearing capacity of the floor, and therefore approved by local authorities.

Old house, the floors were wooden, we removed the joists and boards, we want to fill the screed.

It turns out you need a thickness of 10 cm, perhaps even more.

Is it possible to pour screed of this thickness in an apartment?

The decision is made individually, the following points are taken into account:

What kind of floor slabs are installed in your house, for example, these

But there are floor slabs with a permissible load of 800 kg or more per sq.m.

The age of the house, it is advisable to conduct a construction examination in order to know exactly the permissible load on the floor slab; the older the house, the lower this figure.

Screed weight, cement-sand screed weighs on average 220 kg sq.m.

The weight of the finishing floor covering, for example, tiles with glue, weighs much more than linoleum or carpet.

The weight of the furniture (this is a constant load).

The weight of the users living in the apartment (not a constant load, but it must also be taken into account).

Next, the floor slab is affected not only by your screed, but also by the weight of the ceiling plaster of the neighbors below.

That is, go down to your neighbors and determine how they repaired the ceiling.

The presence of partitions 9 in the same room (this is also a load on the floor slab), if there is a partition, then what kind, for example, a partition made of brick weighs much more than a partition made of gypsum board.

Further, when raising the floor by 10 cm, problems may arise with the heating radiators, or more precisely with the distance from the floor to the radiator; they will have to be raised higher.

Reinstall interior doors, otherwise the door leaf will touch the tie when opening.

Taking all this into account, a decision is made.

If we are talking about a house from an old housing stock, then most often there were joists on the floors and then a floorboard; here you can do without reinstalling the doors and raising the radiators higher; the boards were removed, the joists were removed and the screed was poured.

If the load on the floor slab is acceptable, then in principle it is possible to pour a 10 cm thick screed in the apartment.

Screeds of this thickness are reinforced and do not forget about waterproofing under the screed and installing a damper tape around the perimeter of the room before pouring it.

Before laying the final floor covering, the screed must be completely dry and gain maximum strength.

Screed density and specific gravity of cement and sand

To construct a cement-sand screed (CSS), depending on the criteria specified by the operating conditions, various types of material can be used, differing in composition, density and strength:

concrete with heavy filler;
concrete with light filler;
cement-sand mortar;
dry mixes.

With heavy filler - granite screenings

The filler based on granite crushed stone screenings is the final product of the production of commercial crushed stone with a fraction of up to 10 mm. Concrete screed with granite filler is highly durable, frost-resistant and is used in industrial construction. In civil and residential construction it is used for premises with high operational loads - for basements and ground floors, garages, utility and storage spaces.

The density of concrete prepared using granite screenings is 1400-2200 kg/m³, which classifies it as heavy. The volumetric weight of a 5 cm thick screed for the specified density range ranges from 70 to 110 kilograms per 1 m2, which is a significant additional load on interfloor ceilings, floors with a soil or wooden base.

Light types of solutions - perlite, polystyrene, granules

In many cases, using a light screed will be more effective. It is used in cases where a large difference in heights is eliminated by leveling, when laying pipelines and communications in the floor, and also when it is necessary to obtain additional heat and sound insulating properties of the floor using a screed.

The density of light screed mortars ranges from 500 to 1800 kg/m³, depending on the type of filler and filler, and their proportions in the mixture. In terms of strength, light screed is inferior to mixtures with heavy filler, so sometimes it is used as an intermediate layer with final leveling with stronger solutions.

Do-it-yourself semi-dry screed step-by-step instructions

The entire scope of preparatory work does not take much time and consists of preparing the base for the screed and preparing the working solution.

The coating is carried out on a completely cleaned surface. In addition, it is necessary to carefully eliminate all chips in the base and deep cracks. All delaminations in the base require cleaning followed by puttying. After all work completed, a zero level mark is set.

All work can be described in the form of step-by-step instructions:
Preparation of working solution
If you plan to use fiberglass, then a mixture of sand, fiberglass and cement must be poured into the pneumatic hose blower. After thorough mixing, water is added and the solution is mixed again.
If it is necessary to use a reinforcing mesh, the solution is prepared from Portland cement and sifted sand. This composition allows you to prepare the mixture directly at the workplace. The addition of plasticizers makes the working solution more elastic and easy to use.
In addition, it is possible to use ready-made mixtures with a specially selected and optimal composition. Such mixtures can only be diluted with water in accordance with the instructions and kneaded thoroughly.

Do-it-yourself semi-dry floor screed is performed in accordance with the “floating screed” technology and consists of the following steps:
high-quality cleaning and priming of the base;
laying a special edge tape;
laying a two-centimeter starting layer followed by compaction;
laying reinforcing mesh;
laying four centimeters of semi-dry mixture;
leveling the poured solution using a laser level and installing beacons;
grouting the surface with a trowel and thorough grinding;
the frozen surface is wetted and a cement-sand mortar is laid out on it, which is rubbed using a wooden or polyurethane trowel;
leveling;
dismantling beacons and grouting their installation sites;
final grinding of the finished surface.

If a working solution that already contains fiberglass is used, then there is no need to use a reinforcing mesh.

So, to summarize, the first thing you need to do is carry out preparatory measures in your apartment or house. To do this, you need to set the zero level and pour the mixture over it. The base of the floor must be thoroughly cleaned of dust and dirt, and all existing cracks must be repaired. These factors influence the production of a smooth surface.

To obtain a solution, you should use a ready-made mixture. Add water to it in the amount indicated in the instructions. Of course, you can prepare the mixture yourself, but then you will need a concrete mixer, and the amount of liquid will have to be determined by eye.

When receiving the mixture, make sure that it turns into a lump and water appears, but does not drip. The next stage is the installation of insulating material and beacons. For insulation it is necessary to use polypropylene film.

To level the surface, it is worth installing beacons that will serve as the upper level. In this case, it is necessary to use T-shaped slats. At the final stage, concreting is carried out. The finished solution is distributed along the guide beacons. Be sure to compact the mixture and grout it.

Tips and tricks

In order for the semi-dry screed to set more efficiently and effectively, it is necessary to cover the completed surface with a layer of plastic film. The main drying process takes about twelve hours.

To install ceramic flooring, the semi-dry screed should be left for at least four days, and laying laminate flooring or parquet can be done after twenty-eight days.

The technology of semi-dry screed with the addition of fiber is based on the minimum amount of water used, which is necessary exclusively for high-quality hydration of the cement mixture.

A semi-dry screed allows you to hide most communications, achieve ideal horizontality under a decorative coating, and increase the heat and sound insulation of floors. This coating is very popular when it is necessary to reduce the time for leveling.

What is the density (specific gravity, volumetric weight) of cement-sand screed kg m3

Many technologies and materials are used to install floors and floor coverings, the choice of which depends on the purpose and operating conditions of the room or facility.
The universal materials for performing this type of work are cement-sand mortars and concrete. When choosing, you should take into account the various characteristics of the material for leveling, one of which is the density of the cement-sand screed in kg/m3. This indicator determines the total weight of the screed and the load on the base of the foundation or interfloor ceilings, exceeding which can lead to a decrease in the overall reliability of the building.

How to make a calculation

First you need to determine what kind of cement will be used. For a coating with a large expected load, you need to take a high grade. A universal way to prepare a working solution is to gradually mix cement with sand in a ratio of 1: 4.5-6. You can choose the final option by knowing the brand of cement. After this, fiber and water are added to the mixture.

The approximate amount of fiber fiber is calculated in the proportion of 35-40 g per square meter of flooring. The thickness of the screed is 5 cm.

So, to carry out a dry floor screed, the calculation will be as follows:

Cement - 15 kg;
Sand - 0.065 m3;
Fiber fiber - 35-40 g;
Water - 2.5-3 l.

There is a practical way to determine the readiness of the mixture. Take one tablespoon of the mixture into your fist and squeeze: a little water should come out of a strong lump. Professionals advise additionally using a plasticizer: its consumption is 50 ml per 1 sq.m.

If you need to correctly calculate how much mortar is needed for a dry floor screed for a room of 200 m2, the calculation is as follows:

cement: 15*200 = 3 t;
sand: 0.065*200 = 13 m3 of sand;
fiber fiber: 35*200 = 7 kg.

The calculation is slightly different when using M300 sand concrete. The area of 200 m2 must be multiplied by 6 (layer thickness) and by 18. Then divided by the weight of one bag (40 kg): 200 * 6 * 18:40 = 540 m.