Types and consumption rates of sand-cement mixture m 150 for floor screed, preparation of the mixture

In modern construction, packaged dry mix is ​​increasingly used, ready for use without the need to combine components. Often, for the manufacture of these, it is customary to use branded cement, fractional sand and plasticizers. The entire range of work in which such materials are involved comes down to adding water to the composition and stirring to the optimal consistency. Next, we will consider the universal powder mixture M150 for construction and repair tasks.

Types and areas of their use

Universal dry mixtures differ in composition and purpose, they have their own characteristics and characteristics.
You should pay attention to the marking, the number in which indicates the strength of the original product

M100

M100 products are intended for manual plastering and putty. The mixture is applied in an even thin layer, which leads to material savings. She is easy and pleasant to work with. The mixture retains its properties for two hours from the moment of dilution. Prices for M100 products are quite affordable.

M150

M150 products are the most popular of the varieties of universal mixtures. It is used in virtually all construction work using dry compounds. Unlike M300 and M400, it is used for masonry, plaster, and screed. Factory packaging is presented in 50 kg bags, less often they produce products in 25 kg packaging.

The universal mixture includes Portland cement, sand, mineral powder, plasticizers and other additives. The finished composition can only be diluted with cold water in the proportion indicated on the package.

M150 products are endowed with many advantages: they are reliable, frost-resistant, have good adhesion to various surfaces, high moisture resistance and vapor permeability. It is used in any climatic conditions.

The disadvantages of M150 include poor resistance to increased loads (no more than 150 kg per 1 cubic cm), therefore such a mixture is not used for work with the foundations of multi-story buildings.

The name “universal” speaks of the variety of applications of the M150 composition.

• The plaster mixture is designed for interior and exterior plastering work. Layer thickness can be applied up to 50 mm. After mixing, work should begin immediately: the mixture is in a pliable state for 2 hours. The plaster becomes completely dry and strong after 4 weeks.
• Using the M150 screed mixture, the floors in the rooms are leveled. Checking the level and setting the beacons, the floor is poured with a thickness of 1 to 10 cm. Thanks to the cement base, the floor acquires durable qualities that are resistant to temperature changes.
• The masonry mixture is used for laying gas silicate blocks and bricks of all types. M150 products can be used indoors and outdoors in cold or hot weather; weather conditions do not affect the quality of masonry. The dry mixture has proven itself well in rooms with high humidity.

M200

Product M200 is a masonry mixture. It consists of Portland cement, river sand and special additives. Designed for laying bricks, concreting flooring, constructing simple foundations, repairing walls and processing seams in concrete structures.

M200 can be used for laying garden tiles, as well as for plastering and puttying walls. It is available in bags weighing 50 kg.

M300

Sand concrete M300 appeared on the construction market not long ago, but has already gained popularity. Unlike the M150, it is designed for heavy loads. The products are durable and reliable, have a long service life, adapt well to weather conditions, are moisture resistant, environmentally friendly, and do not shrink. M300 consists of Portland cement, which contains gypsum, sand and crushed clinker. Products are packaged in 50 kg bags, less often in 200 kg bags for industrial scale.

Due to its special strength, the composition is used in all areas of construction work in all climatic conditions. During installation, they are used to install the foundation, floor screed, leveling walls and other surfaces. The product has proven itself well as a grout for cracks during work at emergency sites. The composition is used when laying garden paths, stairs, and borders. The mixture is used in the production of expanded clay concrete.

According to their properties, depending on the application, M300 products are divided into several subtypes.

• Coarse grain has incredible strength and long service life. With its help you can fill the foundations of high-rise buildings.
• Medium-grain is used for screeds, self-leveling floors, work with borders and garden paths. It is used wherever a medium-grained fraction of the mixture is required.
• Fine-grained is also reliable and durable; it is used for plastering work.

When choosing a universal dry composition, you should remember: the more famous the brand and the higher the grade of the product, the more expensive the product and the more reliable its technical properties.

For information on what dry building mixtures are, see the following video.

Problems in the manufacture of cement screeds

Specifications

The technical characteristics of sand concrete determine the rules of its operation and resistance to external destructive factors. The composition and technical properties of the M300 mixture make it possible to use it both as a self-leveling compound (self-leveling mixture) and as a repair composition.

Compound

Any variants of M300 mixtures are gray in color. Its shades may vary depending on the composition. For such materials, Portland cement M500 is used. In addition, the M300 mixture, according to GOST, has the following proportions of the main components: one third of cement, which is the binding ingredient, and two thirds of sand, which is the filler.

Frost resistance

This indicator indicates the ability of the material to withstand multiple temperature changes, alternating thawing and freezing without severe destruction and reduction in strength. Frost resistance allows the use of M300 sand concrete in unheated places (for example, in permanent garages).

Frost resistance of mixtures with special additives can be up to 400 cycles. Frost-resistant repair mixtures (MRMs) are used for mixing construction compounds used in the reconstruction and restoration of concrete, reinforced concrete, stone and other joints, filling voids, cracks, anchors and for other purposes.

Compressive strength

This indicator helps to understand what tensile strength a material has under static or dynamic influence on it. Exceeding this indicator has a detrimental effect on the material and leads to its deformation.

Dry mixture M300 can withstand compressive strength up to 30 MPa. In other words, given that 1 MPa is approximately 10 kg/cm2, the compressive strength of M300 is equal to 300 kg/cm2.

Temperature range

If the thermal conditions are observed at the time of work, the process technology is not disrupted. The continued preservation of all the performance qualities of concrete is also guaranteed.

It is recommended to carry out work with M300 sand concrete at temperatures from +5 to +25? C. However, sometimes builders are forced to violate these recommendations.

Adhesion

This indicator characterizes the ability of layers and materials to interact with each other. Sand concrete M300 is capable of forming reliable adhesion to the base layer, which is equal to 4 kg/cm2. This is a very good value for dry construction mixtures. To ensure maximum adhesive performance, manufacturers provide appropriate recommendations regarding preliminary preparation work.

Bulk density

This indicator means the density of the material in its uncompacted form, taking into account not only the volume of particles, but also the space that has arisen between them. This value is often used to calculate other parameters. In bags, the M300 dry mixture is in bulk with a density of 1500 kg/m3.

If we take this value into account, it is possible to draw up an optimal ratio for construction. For example, with the declared density, 1 ton of material is 0.67 m3 in volume

In small-scale construction work, a 10-liter bucket with a volume of 0.01 m3 and containing about 15 kg of dry mixture is used as a measure of the amount of material.

Sand particle size

Factories produce M300 sand concrete using sand of different fractions. These differences determine the peculiarities of the technique for working with the solution.

There are three main sizes of sand used as raw material for dry mixtures.

• Small size (up to 2.0 mm) – suitable for street plastering work, leveling seams.
• Medium size (from 0 to 2.2 mm) – used for screeds, tiles and borders.
• Large size (more than 2.2 mm) – used for pouring foundations and foundations.

Mixture consumption

This indicator characterizes the material consumption with a layer thickness of 10 mm per 1 m2. For M300 sand concrete it is usually in the range from 17 to 30 kg per m2. It is worth noting that the lower the consumption, the more economical the work costs will be. In addition, manufacturers often indicate the consumption of sand concrete in m3. In this case, its value will vary from 1.5 to 1.7 t/m3.

Delamination

This indicator characterizes the connection between the lower and upper parts of the solution. The M300 mixture usually has a delamination rate of no more than 5%. This value fully complies with the requirements of the standards.

Self-preparation of the solution

Preparation

DSP

The proportions are influenced by several indicators:

• purpose of the solution;
• brand of cement;
• its production.

Take into account that when stored, cement loses its properties, even with proper storage. Thanks to this, the share in the composition is increased taking into account the storage period:

For screeds, take cement 500, 400 in the ratios of part cement 2 sand, part binder material 3 parts sand (for grade 500). To reduce the likelihood of cracks, polypropylene fiber is added to the floor screed at the rate of 0.9 kg per cubic meter. meter.

For masonry, a composition is used in the ratio of part cement and 5 parts sand - it depends on the condition of the sand (how dried, sifted). The solution is carried out in a small volume, determining experimentally the required proportion of the mixture and the consumption of the solution, which optimizes the consumption of material. For plastering, binder grades 200 and 300 are used in a ratio of 1/3.

Attention! It is necessary to mix the solution very carefully, and an attachment for an electric drill is suitable for this; reducing cement consumption, increasing the amount of sand will lead to the appearance of cracks, chips, unnecessary water leads to a decrease in strength characteristics and an increase in curing time.

If the sand-cement mixture

M150 is prepared according to the rules, then after the screed
hardens
it will be durable, high-quality and will serve for a long time. First of all, the proportions and shelf life of cement are taken into account.

Filling the screed with M150 mixture:

What is sand concrete made of?

The characteristics of sand concrete m300 (composition, proportions 1 m³) are standardized by GOST 7473-94.

High-quality dry mixture contains:

• Portland cement PC500 D20/PTs400 D0;
• fractionated dry sand, with a combined composition of fractions (particle size 0.80-4.0 mm);
• other additives (frost-resistant, microsilica, fiberglass) are introduced at the discretion of the manufacturer.

Sand concrete M300 can be used to construct wear-resistant, high-strength floors as a load-bearing covering in utility and residential premises, including garages, basements (with a load of 250-300 kg/cm²)

Depending on the sand used, M300 grade material is used to carry out certain work:

Types and functions of screeds

Main types of concrete screeds
Before mixing a cement-sand mixture (CSM) with your own hands, it is worth understanding what a screed is and why it is needed. Screed is a concrete layer that is located between the rough and finishing coating. The solution can be prepared using several technologies, depending on the type of mixture, the type of base and the requirements for the screed itself. What functions does this coating perform?

1. Helps level wood and concrete subfloors;
2. Masks communications located on the floor;
3. Protects the subfloor from mechanical damage and uneven distribution of load on the coating;
4. A concrete screed allows you to install a “warm floor” system.

In some cases, pouring the solution with your own hands is done in order to achieve not horizontality, but a certain slope of the coating. As a rule, such work is necessary when arranging showers and bathrooms. Depending on the composition of the concrete and the method of preparing the rough base, the following types of screeds are distinguished:

• Separating - the cement-sand mixture is poured onto a layer of waterproofing, which prevents moisture from entering the rough base. This method is advisable to use when repairing subfloors on the ground, as well as on the lower floors of apartments in which the likelihood of moisture seeping under the floor is high;
• Related - the cement composition is poured directly onto the floor, but only if the moisture level of the base is sufficiently low. Pouring mortar with your own hands using this type is often done when repairing interfloor ceilings;
• Floating - it is better to do such a screed only if it is necessary to insulate the base. The solution is poured onto the heat insulator and reinforcing mesh. In this case, the liquid mixture does not come into contact with either the rough base or the walls. The minimum thickness of the screed should reach 60 mm.

Composition of sand concrete m200

The composition of sand concrete is determined by GOST 31357 - 2007 “Dry mixtures for construction with a cement binder”. Each manufacturer can make small additions to the composition of the mixture, but there are key components and indicators that are standard.

Main components:

• Cement m400;
• Sand;
• Crushed stone;
• Water.

When creating, Portland cement M400 is mainly used; it is one of the most common, and its technical characteristics meet all specified standards. Sand is used in two types of fractions - fine-grained and coarse-grained, thoroughly cleaned of foreign impurities.

The composition and proportions of sand concrete m200 per 1m3 according to construction standards, the mixture consumption is:

• Portland cement - 265 (1 part);
• sand 860 (2 parts);
• crushed stone 1050 (5 parts);
• water 180 (? parts).

Good consumption M150

Proportions of solution components

When selecting PDS M150 for operation, its consumption

for a screed is 22 g per 1 m2, this material consumption will be good for a screed 1 cm thick. Cement is considered a binding material, which adds unequal characteristics to it.

The thickness of the layer varies from 5-50 mm and depends on the work performed. This mixture is applied manually. The lifespan of the composition is 120 minutes, thanks to which large volumes are not mixed. The mixture reaches full reliability after 28 days.

Bending reliability is 2 MPa, and adhesion reliability (the process of adhesion of 2 different surfaces) is 0.5 MPa. To increase adhesion, error-free surface preparation is of great importance.

Tips and tricks

When planning to prepare a cement-sand mixture, you must immediately decide in what proportion the different components will be taken, what grade of strength is needed, and what the main properties are.

It all depends on the scope of application of the mortar - so, if M50 or M75 is suitable for brickwork, then for screed prepare at least a mixture of M150, 200 and higher. The composition of any CPS includes cement, sand, water, but the result is different depending on the ratio.

Some tips from the experts:

• To prepare a plastic mixture, you can add liquid soap to the solution, previously thoroughly mixed with water.
• You need to know how to properly dilute cement and other components: first, all the dry substances are mixed, then water is added in small portions so that you can control the thickness of the mixture and achieve the ideal consistency.
• When preparing, take into account the brand of building material from which the walls are built. It is desirable that the parameters coincide - then the wall will have a homogeneous structure, reliable and durable.

• Before you make your own cement for plaster, you should take care of purchasing perlite. If you replace some of the sand with it, you will be able to achieve higher thermal insulation characteristics.
• For work, we use exclusively fresh cement, without lumps, produced according to technology and stored in optimal conditions - in this case, it will be possible to achieve the most uniform mixing and high adhesion.
• Detergent or soap is also added to the cement (the proportions remain the same, it is simply mixed with mixing water) to increase adhesion.
• The solution is best prepared in a container made of metal, plastic or wood.
• To thoroughly clean the sand from impurities that can reduce its strength, you can soak it in water for a short time.
• The consistency of the finished cement-sand mixture is usually checked with a trowel: the solution should be distributed evenly over the tool, but not run off (it is worth remembering that this rule works in the preparation of standard mixtures; for some tasks other properties may be important).

• The finished DSP is used for an hour after mixing, until the solution begins to thicken and harden. Therefore, you need to immediately prepare the required volume - exactly as much as you can produce in an hour.
• It is forbidden to dilute an already hardened solution with water, as it immediately loses its properties and can cause destruction of the structure/building.
• When mixing a mixture in a volume greater than 2 cubic meters, no drills or attachments will help - only a concrete mixer or ordering the required volume at the factory.
• The solution, which is planned to be used where minimal loads and low mass are noted, can be prepared with a reduced volume of sand. But this approach is only possible on the condition that before properly mixing the DSP, the master has precisely determined the specifics of the application and the remaining solution will not be used for the implementation of any other tasks.
• Mixing the cement-sand mass should last at least 20 minutes - this way the solution will be homogeneous and of high quality.
• The ratio of the proportions of the components is looked at in GOSTs and SNiPs (the opinion of experienced craftsmen is allowed), as well as in the recommendations of the manufacturer of cement, dry mix, etc.

Cement-sand mixture is a universal material that can be used to perform a whole range of works, obtaining the most durable and strong structures. Provided you select high-quality materials and follow the technology for preparing the mixture for the task at hand, everything can be accomplished quickly and easily.

Concrete composition

Table of proportions of concrete mixture for laying screed
When mixing the solution, you need to pay attention not only to the proportions, but also to the presence of additional components, such as plasticizers. They can perform various functions, ranging from increasing the degree of frost resistance of the screed to improving the water-repellent properties. The standard composition of concrete includes sand and cement. But even these components may differ in their technical characteristics.

The physical and mechanical properties of sand and cement are influenced by the following parameters:

• Fraction size. Sand can be fine- or coarse-grained;
• Brand of cement. The higher the grade of dry powder, the stronger the concrete surface will be after the screed hardens;
• Degree of humidity. The “rawer” the sand, the less water will be required when mixing the solution.

So, what components are included in the standard composition of the DSP?

1. Cement. To prepare a high-quality mixture, it is best to use powder grade M200 or higher. It is important to consider the “freshness” of the material. Over time, cement cakes, which can affect its quality;
2. Sand. When arranging a screed with your own hands, you need to choose river sand with a small amount of impurities - shells, pebbles, etc. Before adding sand to the liquid mixture, it is best to sift it;
3. Plasticizer. Liquid synthetic additives make the DSP more flexible and easier to work with. Plasticizers affect the rate of hardening of the screed, as well as the degree of its wear resistance;
4. Fiber. This component is needed to prevent cracking of the screed. In a sense, it plays the role of a reinforcing mesh, preventing damage to the coating both during the hardening process and during operation.

Peculiarities

Dry mix M-300 is a ready-made masonry mixture, the components of which are selected in the required proportions. Before use, the composition is diluted with water in the volume specified by the manufacturer and mixed mechanically until smooth.

The mixture is sand concrete, since it is based on purified fine-grained concrete and Portland cement. The dimensions of the first do not exceed 3 mm; the Portland cement used has a grade strength of M-400 or M-500). To ensure certain characteristics (frost resistance, moisture strength, and so on), plasticizers are introduced.

Various reinforcing fibers may be present in compositions operated at subzero temperatures. To improve adhesion, a special type of clay, coarse sand, or granite chips are sometimes added.

Unlike conventional concrete mortars, M-300 sand concrete is distinguished by its ease of preparation, plasticity (suitable for laying in a thin layer, which is necessary for certain types of masonry), high strength, and economical consumption. The M300 mixture is a masonry mixture, that is, it is used for fixing bricks or masonry stones. In addition, it can be used as a concrete mixture for casting.

The composition is characterized by non-shrinkage, which allows it to be used as a floor screed. And thanks to its increased strength and wear resistance, the mixture is used even when organizing high-strength floors. The thixotropy of the composition allows it to be used also for leveling floors, as well as sealing cracks in concrete surfaces.

The material is suitable for both private housing construction and the construction of industrial and administrative facilities, as well as the installation of basements and garages. It is used when pouring the foundation, including in places where concrete and reinforcing sections meet. The mixture is also used to create paths in private suburban areas. In its properties, the material resembles fine-grained concrete, therefore it is used both outside and indoors.

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Floor level markings. Installation of screed beacons.

To achieve the correct level, beacons will need to be installed before pouring. There are several ways to do this, and here is one of the simplest.

Parallel to one of the walls, at a distance of twenty to thirty centimeters from it, we lay out small portions of cement-sand (1:3) mortar (ready-made universal mixture M-150 Prestige-S).

You can also use alabaster mixture, since it hardens very quickly, so you can start pouring almost immediately, but in the case of cement you will have to wait.

General information

A characteristic feature of concrete is its composition, as well as proportions and preparation technology. It consists of cement, fine and coarse fillers, water and various additives. In addition, there are brands of concrete that do not contain coarse filler. There are different mixtures that are used for specific cases and also have different properties.

Designation and its interpretation

Concrete structures gain full strength within 6 months, and in 30 days concrete gains 70% strength. M300 is used in all structures that are subject to significant load, therefore, one of the main indicators is its strength. The MXXX designation template does not indicate a specific brand, but is an indicator of the maximum compression pressure.

In addition, there are other designation patterns, for example, FXXX and WXXX, indicating frost resistance and water resistance, respectively. The M300 class of concrete shows the totality of all grades whose ultimate strength is 300 kgf/sq.m. cm. The tensile strength is tested in laboratory conditions by applying force to parallel planes of a product cast from concrete, in the shape of a cube with a side of 150 mm. The grade of concrete in terms of strength is correlated with its class. These indicators should be selected for the construction and calculation of the finished structure at the maximum load that it can withstand.

M300 corresponds to class B22.5 with a coefficient of variation (CV) that is 13.5%. It shows the homogeneity of the mixture from which any brand of concrete is made. When this coefficient changes, the grade of concrete will also change, that is, if its value is low, the grade will increase and vice versa. If the concrete is M300, then with different values ​​of the coefficient its class will change:

1. At Kv = 5% the class is B25.
2. At Kv = 13.5% - B22.5.
3. At Kv = 18% - B15.

Main characteristics

Concrete is classified into grades, and this distribution is primarily related to the parameters of strength (B), density (D), water resistance (W), frost resistance (F) and workability (P). One of the best options for most construction work is M300 concrete, the characteristics of which are as follows:

1. Strength: B22.5 with an indicator of 295 kg/sq. cm.
2. Specific gravity of concrete M300: 1800−2500 kg/cubic. m.
3. Water resistance: W6-W8.
4. Frost resistance: F200-F300.
5. Mobility: P2-P4.

The strength indicator is the main characteristic and shows the maximum effect of forces during compression, at which the structure collapses. The specific gravity or density of M300 concrete depends on the type of coarse filler included in its composition. When using limestone, the D value is about 1800 kg/m3. m., and when using harder rocks (crushed granite, granodirite, etc.) it can reach a value of 2500 kg/cubic. m. Due to its high density, this type is classified as heavy. The density indicator depends on the presence of violations in the manufacturing technology and air cavities.

Water resistance (WXX) is a value indicating the water pressure in MPa to pass through 0.15 m of concrete. For concrete grade M300, this indicator is equal to W5-W6; at a pressure of 0.5-0.6 MPa (approximately corresponding to 5-6 atmospheres) it does not allow water to pass through at all. By adding hydrophobic cement, additives and carefully compacting the solution, it is possible to increase the waterproof rating.

Frost resistance is indicated in the form of the FXXX pattern and shows the number of defrost-freeze cycles without loss of strength. This characteristic can be increased in several ways:

1. The use of additives that prevent the formation of air bubbles.
2. Removing air from the concrete mixture using vibrators, as well as using various compactors.
3. Reducing the amount of water (impairs mobility).
4. Using solid fillers instead of crushed limestone.

Application in construction

Since M300 has good strength, frost resistance, water resistance and mobility, it is widely used in construction. In addition, its main indicators can be adjusted by changing the components included in the concrete mixture. It is advisable to use it for the following work:

1. Construction of platforms, roads and curbs.
2. Installation of walls and various supports.
3. Construction of stairs, landings and pouring of foundations in multi-storey buildings.
4. Production of reinforced concrete products and fences.
5. Production of sewer pipes that are constantly exposed to moisture.
6. Construction of objects that are affected by constant temperature changes.

How to prepare TsPS?

Each ready-made mixture must be accompanied by instructions on the required amount of water; other components are usually not provided. When used as part of additional materials (dyes, reinforcing fibers), the proportions must be observed strictly in accordance with the instructions for the additive. The typical ratio of mixture to water is 5 to 1 (a bucket of water per 50 kg bag of mixture), the share of dyes is 0.1%, the share of fiber fiber is 1%.

When making it yourself, the proportions of water and sand to cement are taken depending on the type of work being carried out, strength requirements, and the degree of moisture content of the sand:

1. The thickest mortar required for masonry is the water/cement ratio of no more than 0.8.

2. For screed and plaster, sour cream-like compositions with a W/C ratio of 0.8–1.2 are used.

3. When spraying and grouting, dilute the solution even more, up to W/C - 1.5.

4. Mixtures with W/C less than 0.6 are used when it is necessary to obtain a quick-drying high-grade cement-sand mortar (M300 and higher), or for concrete.

If a concrete mixer is used for mixing, it is recommended to carry out the work in the following order:

• Pour water into the untwisted drum and add additives.
• Add 2 buckets of sand.
• Add a bucket of cement and wait for it to mix.
• Add the remaining sand and add water if necessary.

When kneading by hand, water is poured into the dry mixture. If you do the opposite, water forms a film of cement on the surface of small lumps of the mixture, which will slow down the process many times over. If the composition is made from its own components, it is advisable to mix them dry before adding water.

Once prepared, the solution must be used before it begins to harden - from 15 minutes to several hours, depending on the use of additives, cement concentration and temperature. The usual solution M150-M200 at a temperature of 20 ° C begins to harden an hour after mixing.

Consumption

To plan the mass of the CPS in advance, you need to approximately calculate the required volume of solution and multiply it by the cost per 1 m3 indicated in the description of the mixture. Most often they are indicated in the format “mixture consumption per m2”, meaning a layer 1 cm thick. To get the costs per 1 m3, just multiply the indicated value by 100.

The usual consumption values ​​for sand-cement mixture are 1800 kg/m3, for high-quality compositions - up to 2200 kg/m3, for lightweight plasters with lime - 1200-1600 kg/m3.

Calculating the volume of consumption of mortar for plastering work and screed is not particularly difficult, but the cost of material for masonry depends on the skill of the particular performer. If you strictly follow the technology, the solution consumption will be 25% of the total volume of the wall, but in practice this value can be either up to 35% (thick seams, losses due to splashes) or below 20% (waste masonry, use of poor-quality techniques to speed up work ).

Key Features

The main purpose of this composition is to perform masonry, as well as installation tasks and finishing procedures. The main positive properties include the ability to create a plastic, high-strength structure, necessary for the implementation of various construction or installation schemes, as well as for masonry and plastering procedures. This material is supplied in bags: base weight - 50, 40 or 25 kg.

Attention! As already mentioned, the required amount of powder is diluted with liquid. In this case, it is best to use a professional mixer or drill with a special attachment. This should be done according to the instructions that manufacturers often put on the bag. If the packaging and accompanying documentation are not provided with relevant information, it can be obtained by reading thematic articles on our blog.

Plasticizing additives and other components in an effective ratio provide the following advantages of the solution:

• reliability and excellent quality;
• good adhesion to most surfaces;
• multi-cyclic frost resistance;
• economical consumption of dry mixtures;
• vapor permeability;
• moisture resistance.

Important! The versatility of this mixture is as follows: it is used for both internal and external procedures; suitable for use in temperate climates or cold northern winters; often used when fastening bricks and other blocks, leveling rough planes, and also when concreting is carried out.

Peculiarities

Cement mortars with sand are used to perform a wide variety of work during the construction, finishing, and renovation of buildings. It’s not difficult to make a mixture with your own hands, but you need to know the exact proportions of cement, sand and water. The easiest way to mix is ​​to use a concrete mixer, renting or purchasing one.

Before making a solution of cement and sand, it is necessary to decide on the scope of application, since the proportions differ within significant limits. The most popular is considered to be DSP for brickwork: cement-sand mortar is used to create load-bearing walls, and with the addition of lime for internal walls.

The composition of the cement mortar largely depends on the working conditions and operation. If work is carried out in frosty conditions, then special anti-freeze additives are added to the composition to prevent the CPS from freezing. But they are suitable for working in frosts below -20 degrees (it’s better not to do anything at all, but to wait for warmer weather), since they will not be flexible and flexible enough.

If a cement solution is prepared for use in monolithic hearths with an open fire source, in the construction of a furnace or firebox, then heat-resistant fire-resistant mixtures are created: from cement of at least M400 grade, with crushed brick, fine fireclay sand.

For each type of task and working conditions, a solution is prepared from basic materials, but in different proportions and with the addition of additives and plasticizers. As a rule, additives change one parameter - this could be the rate of hardening, mobility, frost resistance, etc. Each master determines priority tasks and performs calculations before preparing the cement mortar.

Screed strength according to SNiP

Table of strength of concrete classes
In order for the cement composition to acquire maximum strength after hardening, it is very important to maintain proportions during its preparation. The service life of the concrete and, as a consequence, the finishing coating will depend on the degree of wear resistance of the coating. Few people think that the screed experiences not only the dynamic load created by a person when walking. The weight of the finished floor, furniture and other equipment also creates a very serious load on the coating, which over time can affect the integrity of the base.

What concrete strength will be optimal? The degree of wear resistance is determined by several factors:

• purpose of the premises (industrial, residential, commercial);
• type of finishing coating;
• floor structure.

According to the requirements of SNiP, prescribed in Article 3.0401-87, the minimum strength of the screed must reach 150 kg/m2. Also, in the recommendations for the construction of floors, regulated by SNiP, the strength of the concrete used to level the base must be at least 15 MPa. Taking into account the above points guarantees maximum wear resistance of the screed.

It should be noted that the SNiP standards regarding the organization of the rough foundation also indicate the following parameters:

Composition of semi-dry screed

1. When creating a concrete slope on an interfloor floor, the compressive strength of the CFRP can be at least 10 MPa;
2. In article 2.03.13-88, mentioned in SNiP, when constructing a self-leveling finished floor, the strength of concrete cannot be lower than 20 MPa;
3. One of the paragraphs of Article 3.0401-87 SNiP explains that the degree of strength of lightweight concrete laid on thermal and waterproofing should be equal to 2.5 MPa per cm2 of coating.

According to the above requirements, the preparation of the working solution must be done using cement grade M150, not lower. At the same time, experts recommend taking building mixtures of the best quality, without focusing on the lower limit of acceptable standards.

To mix the liquid composition with your own hands, you can use the following schemes:

• Ready-made mixtures - compositions are made on the basis of cement, various additives (plasticizers) and sand. Depending on the concentration of individual components, the resulting screed can acquire the necessary technical characteristics - frost resistance, moisture resistance, etc.;
• CPS is a liquid composition that includes cement and sand in a ratio of 1 to 3. This type of mortar has high compressive strength, so it can be used for arranging rough foundations in private and commercial construction.