Dry building mixtures: description, marking, classification

Dry construction mixture (CCM)) - a mixture of binders, fillers, fillers and additives - when mixed with water, it forms a mortar mixture that is capable of spontaneous hardening over time to form an artificial stone.

The fundamental difference between SSS and traditional mortar mixtures is the presence in SSS of a complex of modifying additives that impart special properties to both mortar mixtures during use and hardened solutions during operation: maintaining cohesion and elasticity over time even when applied to a porous base, increasing the limit tensile strength and a decrease in the elastic modulus, which provides increased shrinkage and temperature crack resistance, increased adhesion to the base, incl. non-porous, etc.

The modification allows the use of SSS for special types of decorative decoration, incl. thin-layer finishing. Hardened solutions obtained from SSS are characterized by quality indicators depending on the purpose of the mixture. Adhesion of adhesives to various substrates ranges from 0.2 to 2.5 MPa.

Fractionated sands with a particle size, depending on the purpose of the SSS, from 0.315 to 5 mm are used as fillers in the composition of the SSS. Dispersed materials (less than 0.16 mm) are used as fillers: carbonate (marble) flour, etc. The main purpose of water-retaining additives is to prevent the loss of water from the mixture when applied to a porous base for a period of time sufficient to perform operations to level the mixture, etc. This property depends on both the dosage and the type of additive.

Derivatives of methylcellulose or starch ethers are used as water-retaining additives in the composition of SSS, which, in addition to water-retaining ability, can provide “thickening” of the mixture, giving it cohesion and elasticity.

The dosage of the water-retaining additive ranges from 0.05% to 0.4% by weight of the SSS (in SSS technology it is customary to indicate the dosage of modifying additives in % of the mass of the mineral components of the SSS), depending on the type of mixture.

As superplasticizers, dry compounds based on naphthalene formaldehyde (SP-1, S-3), melamine formaldehyde (Melment), and polycarboxylates (Melflux) are used. The dosage, depending on the type of superplasticizer and the type of SSS, ranges from 0.1% to 1.2% of the mass of SSS.

Noticeable quantities of modified dry building mixtures (MCMs) in Russia have become available since the mid-90s of the last century. Over the past decade, these materials have become firmly established in construction practice.

The production of SSS in Russia is growing rapidly (Fig. 2).

Rice. 2. Production of SSS in Russia

Most of the output is made up of cement-based mixtures (Fig. 3); at least a third of the production volume is made up of gypsum mixtures. Mixtures based on polymer binders are produced in small quantities.

Rice. 3. Shares of SSS on various binders

Concrete

Concrete is an artificial stone composite material obtained by hardening a rationally selected mixture of binder, water, aggregates and, in some cases, special additives. Before hardening, this mixture is called concrete. Aggregates and water make up 85-90% of the concrete mass, binder - 10-15%.

Concrete can be classified according to a number of characteristics.

By average density

particularly heavy concretes - with an average density of more than 2500 kg/m3, manufactured using heavy aggregates (magnetite, barite, cast iron scrap, etc.). Such concretes are used for the manufacture of special protective structures; heavy - with an average density of 2200-2500 kg/m3 on sand, crushed stone or gravel from heavy rocks. They are used in all load-bearing structures; lightweight - with an average density of 1800-2200 kg/m3, used mainly in load-bearing structures; lightweight - with an average density of 500-1800 kg/m3. These include lightweight concrete on porous natural and artificial aggregates, cellular concrete (aerated concrete, foam concrete), large-porous (sandless) concrete on dense or porous aggregate; especially light (cellular and porous fillers) - with a density of less than 500 kg/m3, used for thermal insulation.

Concrete	Density, kg/m3	Features of the composition	Application
especially heavy	more than 2500	using heavy aggregates (magnetite, barite)	special protective structures
heavy	2200-2500	heavy rock aggregate	bearing structures
lightweight	1800-2200	porous aggregates	bearing structures
lungs	500-1800	cellular concrete (aerated concrete, foam concrete)	low-rise construction, thermal insulation
extra-light	less than 500	cellular and on porous fillers	thermal insulation

By type of binder

There are cement concretes (the most common), slag concrete, lime concrete, mixed silicate concrete (cement-lime, lime-slag, etc.), silicate, gypsum, and slag-alkaline concrete. asphalt concrete, polymer concrete, etc.

By type of fillers

There are concretes made from dense, porous, special aggregates that meet special requirements (protection from radiation, heat resistance, chemical resistance, etc.).

By purpose

Concrete is divided into
structural and special . Structural ones
are used for the manufacture of load-bearing and enclosing building structures. The main indicator of the quality of these concretes is strength. Depending on the specific operating conditions, they may also be subject to additional requirements for water resistance, frost resistance, corrosion resistance, etc.

Special

concretes are designed to work in special conditions. Thus, heat-resistant concrete is used to protect structures at temperatures above 800°C; chemically resistant - in aggressive environments; radiation-resistant - for protection against exposure to radiation; thermal insulation - for thermal insulation of premises, equipment, etc.

At the macro level

concrete consists of coarse aggregate grains and a matrix represented by cement-sand mortar.
The mesostructure level
includes fine aggregate and a hydrated cement matrix.

At the micro level

concrete consists of cement hydration products (portlandite, ettringite, calcium hydrosilicates, gel phase) and its unhydrated grains, pores and water filling the pores.

One of the important characteristics of concrete is its pore structure, or pore space, defined as the volume not filled with a solid phase. The pore structure of concrete is formed from the moment the dry mixture is mixed with water until it hardens and an artificial conglomerate is obtained.

Production, use and composition of dry construction mixtures

Therefore, it seems absolutely natural that manufacturers want to keep the recipes of all their mixtures secret. The same cannot be said about the general principles of the formation of specific characteristics of materials.

The composition of modified dry mixtures includes four main groups of components: inert fillers, mineral binders, polymer binders and additives that add special properties.

Binders of mineral origin

The most frequently used hydraulic mineral substances are Portland cements of two colors: white and gray, a- and a-hemihydrate gypsum, highly aluminant fast-hardening cements, and combinations of these materials.

If gypsum and cement are subjected to joint hydration, a considerable amount of ettiringite is formed - a mineral that, if present, can cause the destruction of the material.

At the moment, lime is most often used as an additive to cement materials (5-30%). It allows you to increase the processability of the mixed solution. This material is also used as the main astringent, but only in special compositions that are intended for the restoration of buildings of historical significance. If the selected filler has low porosity, sufficient intrinsic strength and dense packing, then we can say that the density and strength of the resulting mineral mixture will depend only on the binder and its properties.

The characteristics of cement, even if the manufacturer is the same, unfortunately, can vary quite a lot depending on the batch. And this, despite the unchanged recipe, leads to a change in the properties of the dry mixture itself. Despite the fact that our country can be proud of a huge number of CaCO3 deposits, there are many problems with the quality of lime. Therefore, it is worth remembering the international quality management system DIN ISO 9001. It is believed (and erroneously) that a company with an ISO 9001 certificate is guaranteed to produce only high-quality products. But this statement is not entirely true.

This standard is not intended to define the quality characteristics of a material. It only guarantees that the manufactured products are characterized by the stability of their properties. A special commission comes to inspect enterprises wishing to receive a certificate to conduct an inspection. She evaluates the condition of the equipment, checks technical documentation, organization of the production process and the quality of raw materials.

And only after a comprehensive analysis of the results obtained after such an audit, a decision is made to issue or refuse to receive this certificate. In the future operation of the enterprise, if any changes are made to the technological process that may affect the compliance of the manufactured product with the requirements set forth in regulatory documents, the manufacturer must notify the commission that issued the certificate. And the commission, in turn, after reviewing the application, will decide whether re-certification will be carried out.

If the ISO 9001 mark is present on the packaging or technical documentation of the dry mixture, this means that the product was manufactured at a certified enterprise, and the information contained in the description is completely truthful.

Fillers

Most often, when dry mixtures are produced, quartz sand and limestone flour are used as a filler. But using dolomite instead of such flour is not advisable, since it contains a large amount of soluble magnesium salts, which can cause the formation of efflorescence.

The composition of plaster mixtures used for thermal insulation includes porous fillers (perlite, expanded clay and vermiculite) and sometimes granulated polystyrene foam. While the need to use only the highest quality cement is clear to everyone, the advisability of using fillers (including sand) is far from obvious to a non-specialist.

However, the quality of dry mixtures does not depend on the granulometric composition of the filler alone. It is also affected by the content of foreign additives, which by their presence can significantly affect the final result. For example, even the presence of a small admixture of clay can greatly reduce the adhesion of a solution, and the content of certain soluble compounds can cause the destruction of organic additives, which are quite expensive. In addition, the composition of the mineral filler may contain chemical compounds (active aluminum oxide, for example), which can affect the hydration of cement. To avoid such troubles, manufacturers try to use fillers that were obtained from one source. This ensures consistent quality of the product. For example, the Vetonit brand, which is always popular among builders, produces its materials at the Optiroc plant, located in the center of the quarry. Sand from the same deposit is used as filler.

Since the scope of the article does not allow us to consider in detail such really important parameters of the filler as porosity and hardness, it is better to briefly dwell on the sieve characteristics and the influence they have. Most solutions that are intended to be applied in a thin layer (thin plaster and tile adhesive) usually contain grains that are no larger than 0.6 mm in size. Compositions that are intended to be applied in a thick layer, decorative, also include here, have larger grains. For smooth solutions - jointing mass and putty - grains no larger than 0.1 mm are typical. The maximum value of mechanical indicators (tearing force, for example), with the consumption of chemical additives at a minimum level, can be achieved if the filler contains approximately equal proportions of various fractions, that is, it has a fairly dense packing.

Modifying additives

When formulas for modified dry mixtures are created, the use of modifiers (special additives) is due to the fact that it is necessary to obtain materials with certain technological and technical characteristics. First of all, we are interested in the need to retain water in the solution after it has already been applied. Water penetrates into the base of the solution and evaporates from its surface, this leads to the fact that:

– the degree of hydration decreases; – the residence time of the material in the gel phase is reduced; – as a result, strength decreases.

Therefore, the thinner the layer of mortar, the greater the impact these shortcomings will have on the quality of the cement stone.

At the beginning of the 20th century, a method was developed in Germany that made it possible to obtain water-soluble cellulose ethers. According to the results of the study, it turned out that due to the fact that there is a weak intermolecular interaction with water molecules, such polymers have a remarkable ability to retain water. Each polymer molecule can hold about 20,000 water molecules.

The energy of such interaction can be compared with the energy of capillary diffusion and evaporation, and this is an obstacle to the escape of liquid. At the same time, this energy is slightly less than the diffusion energy during cement hydration, which allows it to take away water.

The water in the cement mortar is replaced with a homogeneous jelly-like solution of methylcellulose, in which particles of filler and cement are suspended. After the water leaves, the polymer remains on the surface between the filler and the cement stone in the form of a thin film. However, it does not in any way affect the hardened solution and its mechanical characteristics. Thus, if a small amount (approximately 0.02-7%) of water-soluble cellulose ethers is added to cement-sand mixtures, this will lead to a fairly significant increase in open time and will allow the material to hydrate evenly throughout its entire volume, and will also provide improved quality characteristics surfaces and a significant increase in adhesion to the base.

The thicker the solution layer, the less methylcellulose will be required to provide the required degree of initial hydration. That is why the minimum thickness of the applied composition must be indicated on the label with the building mixture. At the same time, it is unacceptable to apply a solution in a thick layer (more than 10 mm) that contains a high percentage of cellulose ether, which is intended for thin-layer technology. In this case, the so-called “caramel effect” often appears - normal hardening of the surface occurs, but a cement solution that has not yet hardened remains inside. Therefore, in order to prepare uneven bases, the differences of which are more than 10-15 mm, it is recommended to use a material system consisting of a thin-layer leveling mass (it ensures a smooth final layer, on which the floor covering will subsequently be laid) and a dry mixture suitable for rough alignment. A systematic approach allows:

1. Avoid all the troubles listed above; 2. Reduce material costs.

The next group of additives includes dispersion powders that, when mixed with water, form, in contrast to water-soluble cellulose derivatives, not solutions, but two-phase systems that consist of polymer particles dispersed in water. By adding such compounds to construction chemical products, it is possible to significantly influence the quality characteristics of the resulting product and provide results that cannot be achieved using only traditional mineral binders. The first attempt to modify cement mixtures with polymers can be called the well-known PVA glue. The process of formation of vinyl acetate film entails significant shrinkage, approximately 10%, and this leads to cracking of the polymer-cement material. For this reason, the use of PVA was soon abandoned.

The next stage is the use of two-component compositions, which consist of a sand-cement mixture produced in a factory and a polymer dispersion, which is supplied in liquid form, mixed at the construction site. Such solutions are still used to this day, but due to the loss of properties by the aqueous dispersion when freezing, in cold seasons the preparation of the solution and transportation of the dispersion causes considerable difficulties.

In 1953, production of one-component dry mixtures began. Dispersions differ from methylcellulose in their mechanism of action. As water is consumed, it begins to concentrate in the pores of the cement stone, and the dispersion also concentrates there, thus forming “elastic bridges” that work in bending and stretching much better than the cement itself. By combining polymer and binders, it is possible to produce a wide range of construction products that will have not only increased strength, better adhesion (even to rather “problematic” substrates such as wood, metal, glazed tiles, plastic and others), but also controlled by special ( fluidity, hydrophobicity) and rheological (plasticity, thixotropy) characteristics. For example, solutions necessary for leveling floors contain a mixture of special dispersion additives and synthetic and organic plasticizers, which determine their specific properties: the smoothness of the resulting surface and the ability to spread. Dispersion modifiers, which are included in adhesive solutions for working with tiles, can improve working conditions, extend the service life of the mixed solution and increase the ability to become thicker at rest and thinner when stirred (thixotropy).

In addition to providing better adhesion of the material to complex substrates, dispersion powders take on the function of a polymer binder. This especially happens in cases where the capacity of cement-sand mortars modified only with cellulose ether is less than the magnitude of shear loads. Thanks to the plasticity of adhesive compositions, it becomes possible to compensate for thermal stresses that arise between the base and the facing material. And first of all, this applies to facade systems, which are subject to daily temperature fluctuations and “warm” floors, the temperature differences of which are also quite large. Too high a polymer content, which is approximately 20-30%, leads to the fact that the cement no longer becomes a continuous crystal lattice, and the individual parts of the stone are connected to each other only by elastic polymer chains. Typically, these materials are used for waterproofing.

A large number of manufacturers of building components offer dispersion powders whose film formation temperature is approximately 0 degrees. This allows the use of dry mixtures with the addition of these materials at fairly low, but not yet negative, temperatures. There are brands of dispersion powder that have a film formation temperature of approximately -15 degrees. Solutions containing such powders are designed to carry out all types of construction work during the cold season, when the air temperature drops no lower than -10 degrees.

Compiling a recipe for dry mixtures can be called a rather lengthy and complex process, which is not possible without the participation of qualified specialists. It is also necessary to have a laboratory with the latest equipment. Therefore, you should beware of attempts to “improve” ordinary cement mortars with your own hands.

The widespread practice of our compatriots to “modernize” simple cement mixtures with PVA glue does not lead to any positive results. Since vinyl acetate has low resistance to alkali solutions, which also causes its saponification in certain places with high humidity levels. That’s why ceramic tiles, which were laid on a solution diluted with PVA glue, fall off.

Quality and price

Having carried out a comparative analysis of prices for dry mixtures that are presented on the Russian market, you can see that a significant part of the products produced in the countries of the post-Soviet space costs significantly less than the same product, but produced in Western European countries. And our consumers believe that this approach is absolutely justified. Indeed, locally mined raw materials, inexpensive labor, minimal transport costs and the complete absence of customs duties seem, but only at first glance, to be direct prerequisites for lowering prices for building materials. But if we look at this situation differently, everything looks a little different.

The production of redispersible powders can be called an extremely complex process that requires the use of specialized unique equipment and pre-treatment of dispersions. In this regard, there are no more than ten companies around the world capable of producing modifiers for construction chemical products of truly high quality. Recognized additive manufacturers: Wacker, Bayer, Clariant, Finndisp, Henkel-Nopco and others. And no one can call the products of these foreign companies cheap.

The price of the dry mixture is mainly determined by the cost of its components. Moreover, if the level of modification is higher, the costs of mineral components have a rather small share, but in this case, chemical additives become the main pricing criterion. For example, one of the cheapest and simplest compositions is domestically produced tile adhesive. Its cost does not exceed 110 rubles. It is a mixture of cement and sand with the addition of methylcellulose (approximately 0.4%). If you consider that one ton of cement itself costs about 100 rubles, and 1 kilogram of methylcellulose costs 220-230 rubles, it becomes clear that about half the cost of the starting materials is additives. Technological and technical properties, such as water resistance, strength characteristics, adhesion to materials with low water absorption and frost resistance, of these adhesives absolutely do not meet the requirements put forward by European countries. But at the same time, these adhesives are in considerable demand not only in our country, but also in Western Europe. According to the EN 12004 classification, more expensive adhesive compositions are approaching class C1, with prices ranging from approximately 110 to 200 rubles. In addition to methylcellulose, such compositions also contain 2% redispersible powder. High-quality elastic adhesives - class C2 materials - have a higher polymer content (approximately 4%), which is more elastic than in the compositions of the previous class, and contain methylcellulose of a more viscous type. Their cost is more than 200 rubles.

Some of the most complex materials, according to the recipe, include masses that have self-leveling abilities and are used for thin-layer application. To control the spreadability, they use the following technology: take 2 identical metal rings, the diameter of which is 40-70 mm, and fill them with solution. One of the rings is immediately lifted, thereby allowing the solution to spread over the surface, and the second of them is lifted after 15 minutes. The area of ​​the resulting two spots should be the same or differ by no more than 15%. Another important property of materials is the ability to drain. You can check it by pouring 2 “puddles” of solution at intervals of 15 minutes; as a result, they should merge into one spot without forming a noticeable boundary. In addition to the ability to spread, self-leveling solutions must have good adhesion to the base and considerable resistance to abrasion, they must provide the necessary strength (even despite a thin layer), and they must not delaminate when poured. Because of this, self-leveling mixtures often include more than 20 components, the price of “chemistry” becomes more than 90%. In this case, the share of fillers and Portland cement no longer significantly affects pricing. Therefore, there is absolutely no need to skimp on mineral components. A certain reduction in the price of products can be achieved only if the recipe is correctly drawn up.

The conclusion is quite simple: the cost of several specialized dry mixtures that have a high level of modification and identical technological and technical characteristics cannot differ significantly. And the country of production is not important: Russia or Germany, for example.

So how can one explain such a difference in the price of materials, even from the same manufacturer, which have identical final quality indicators (tensile strength, compression strength, adhesion, etc.) and are recommended for the same conditions of use and operation? This is due to the fact that in most foreign companies the assortment policy clearly follows the needs of consumers, which are quite often determined by the economic and sometimes national characteristics of the region. In countries with a high level of economic development, not a single company allows itself such an unaffordable luxury as employee downtime.

This type of organization of repair and construction and finishing work involves the use of only quick-setting mixtures, which can minimize the inevitable breaks between several operations. Such compositions are characterized by a high content of modifying additives in their composition, resulting in a rather high cost. For example, according to the regulations in force in Germany, it is allowed to walk on a surface leveled with a leveling mass after only three hours. All building materials made in Germany, such as Knauf, Henkel, Uzin UTZ AG, Dyckerhoff and others), which are intended for sale on the German market and in some Western European countries, meet these requirements. However, in our country there are no such norms at all. In Russia you can buy imported material of the same purpose, which also has the same technical characteristics, but you will be able to walk on it only after 8 hours. And the price for such a product will be three times lower.

Russian manufacturers have in their arsenal materials that are even cheaper. For example, the leveling mass “Unis Horizon-2” allows you to walk on the surface only after at least 36 hours. Due to the fact that the company has reduced the content of modifying additives, which accelerate the hardening and setting of the solution, this has enabled the company’s specialists to produce an inexpensive (and therefore widely used) material with excellent technical characteristics. A customer who has sufficient financial resources and is interested in reducing construction time will most likely choose the first mixture option. But those for whom cost reduction according to the estimate is more important will prefer option number two. You don’t have to worry about the final result, regardless of which mass option was chosen, because both aligned bases will be quite close in their characteristics. The above example clearly shows the need to accurately formulate the requirements that you want to present to the material in each individual case, and to carefully study the price, technological and technical characteristics of the mixtures.

It’s great, realizing how important it is to reduce time consumption, some of the Russian companies have also mastered the production of mixtures that harden in 3-4 hours, for example, Glims-SL and Glims-S3X. But, as you understand, miracles do not exist, so the prices for such materials are almost equal to the prices for foreign-made materials.

Dry mixes. Classification

In modern conditions of construction and finishing work, dry building mixtures are increasingly used, which are carefully dosed and prepared in the factory, and only mixed with water at the construction site. Dry building mixtures are compositions consisting of binders, fillers, fillers and additives (modifiers, antifreeze, dyes, etc.), prepared in a factory.

Dry building mixtures are classified according to the following criteria:

- type of binder;

- main purpose;

— conditions and degree of modification of the mixture with various additives;

— conditions of use;

Based on the type of binder, dry building mixtures are divided into gypsum, lime, magnesium, cement, polymer and mixed.

For their main purpose, dry building mixtures are used for masonry, cladding, putty, plaster, and there are also joint mixtures, adhesive sealing compounds, etc.

According to the conditions and degree of modification, the mixtures are divided into standard, high-quality, economical, and superior quality.

According to the conditions of use of construction and finishing works - manual and automated application, for porous materials, etc.

Dry mixtures containing one type of binder are called simple , mixed binders are called complex .

The type of binder determines the hardening conditions and operational properties of dry mixtures, including moisture conditions, frost resistance, and resistance to cyclic wetting and drying.

Based on the size of aggregates and fillers, dry mixtures are divided into concrete, mortar and mixtures for thin-walled technologies with a filler size of no more than 1.25 mm, which are also called dispersed.

In most cases, ordinary and white Portland cement are used for the production of dry mixes. White cement is used for the manufacture of putties, decorative plasters and special types of glue.

For emergency repair work, expanding compositions, and quick-hardening mixtures, alumina cement is used.

Gypsum binders are used as additives in cement mixtures and as the main structure-forming components in putty and finishing compositions.

Quartz sand, chalk, limestone, microsilica, kaolin, dolomite, etc. are used as fillers for dry mixtures.

For dry mixtures intended for highly water-resistant and waterproof coatings, bentonite clay is used as a filler.

Performance qualities of dry construction mixtures

Among the most attractive operational advantages of dry construction mixtures for consumers are:

• practicality in use and ease of preparation thanks to detailed instructions, usually placed directly on the original packaging of the product;
• proportions of initial components maintained within the framework of GOST, which ensures strictly specified properties of the final product of each specific brand;
• attractive price, ensuring high efficiency of using the described building material due to the possibility of creating a thin layer of mortar and reducing the time for its preparation;
• plasticity, homogeneity and good adhesive properties of the mixture, which, subject to operating rules, guarantees its reliable adhesion to the base and high-quality application on any type of surface;
• environmental friendliness, since all modern mixtures of the construction category are one hundred percent safe for the natural environment and human health;
• maintaining working qualities even after prolonged storage in warehouse conditions and transportation, including at low temperatures.

When choosing dry mixtures for individual construction operations, it is useful to be guided by the principle of loyalty to one manufacturer. Such products are ideally combined with each other, ensuring the durability of the structure and the quality of the finished work.

Dry mixes

Dry building mixtures are auxiliary materials used in the construction, finishing and repair of premises that have special properties. Depending on the composition, dry mixtures based on gypsum and cement are distinguished. They are a powdery substance that consists of mineral binders, fillers and modifier additives. Water is added immediately before work. Dry building mixtures are used in puttying, masonry, tiling, hydro- and thermal insulation work, flooring, leveling walls and ceilings.

Plaster is a finishing, leveling coating. It is applied in the form of a plaster mortar to the surface to be finished inside or outside the building. There are gypsum, cement, cement-lime and multi-component types of plaster. Gypsum plasters create a flat and smooth surface, suitable for subsequent wallpapering or painting. They are plastic, easy to use, “breathe” and are fireproof. Used for interior work. Cement-based plasters are used for leveling concrete and brick surfaces. They are waterproof, have high adhesion, are durable and flexible. Cement-lime plasters provide good adhesion to concrete, aerated concrete, brick surfaces, and ceramic blocks. Multicomponent plasters, which have a complex composition, contain additives that improve the durability of the coating.

Putties are used for final, finishing, and interior work. These are dry mixtures, soluble in water, or paste-like materials, ready for use.

A special putty is designed for sealing joints of plasterboard sheets and panels based on them.

The putty is prepared on the basis of gypsum and in combination with reinforcing tape and is also intended for sealing seams formed by plasterboard sheets, sealing cracks and other defects on them, for gluing plasterboard sheets and combined panels to a flat surface, for sealing seams, cavities and irregularities in precast concrete elements for gluing and puttying gypsum elements.

Easy-to-sand putty material “Finish Paste”, designed for applying a final thin layer to a previously laid base putty.

Tile adhesive is an indispensable material for finishing work. For a long time, the tile composition did not change, so it was possible to buy only cement-sand mortar, rarely with plasticizer additives. Now things are completely different. The structure of the tile mortar has completely changed due to the polymer components, acquired properties such as water resistance, increased strength and adhesion, and has become elastic and less porous. Tile adhesive of the previous generation was supplied in the form of two components - a dry mixture plus a special liquid; today the adhesive just needs to be diluted with water to the desired consistency.

Self-leveling floors are mixtures for leveling floors and installing screeds for any covering. They are used as a carrier layer to create a durable and smooth finish, ideal for subsequent installation of parquet, linoleum, ceramic tiles, carpet and other floor coverings. Self-leveling floors are used to level surfaces with differences from 3 to 30 mm. Leveling mixtures are characterized by self-flowing and self-leveling. The most common self-leveling floors are cement-sand based, which contain fillers and special additives that ensure the formation of horizontal, durable, wear-resistant, non-shrinking surfaces.

Mounting mixtures have a wide range of applications when carrying out installation, repair and restoration work in foundation foundations, for anchoring building structures made of plastic and metal, for installing adhesive layers, filling cracks in concrete and reinforced concrete structures, both inside and outside buildings. There are mounting mixtures based on gypsum and cement. The composition of the mixture determines its purpose and qualities, such as adhesion to the surface, frost resistance, ductility, strength, ability to “breathe” and lack of shrinkage. All installation mixtures are characterized by environmental friendliness.

Machine-applied mixtures are intended for leveling and finishing various surfaces with a base of concrete, foam concrete, brick, plaster, using special machines and manually. They are floor screeds, gypsum and cement based plasters. The latter have moisture resistance, strength and a wide range of operation. Machine-applied mixtures are quickly applied and leveled, which allows for time savings, high labor productivity and reduced cost of work, especially on large sites. Machine application provides lower consumption of the mixture, and, as a result, reduced load on supporting structures. At the same time, the surfaces have the quality of finishing.

Decorative plasters are thick-layer, facing layers, colored or textured, used during interior and facade work to create relief surfaces. Their use eliminates the need for finishing. Modeling decorative plasters have a texture that is determined by the shape and size of the filler, the technology of application and application, as well as the tool used: grater, spatula, roller. Due to decorative textures, the surface acquires a magnificent appearance. Decorative plasters are highly durable and resistant to weathering.

Waterproofing mixtures are specialized high-tech materials for waterproofing walls and foundations of various buildings and structures.

Varieties:

1. Blocking waterproofing. By using this material to seal and repair cracks, seal seams and holes, any water leak can be eliminated in just a few minutes.

2. Rigid coating waterproofing is used for sealing building foundations, waterproofing basements, indoor swimming pools, basements, bathtubs and showers. Simplicity of use and ease of subsequent finishing of the waterproofing layer provide convenience when working with the material, and the increased water resistance and water resistance of the resulting coating reliably guarantee the durability and reliability of the building structure.

Scope of use of dry construction mixtures

Plasters

Plaster is intended for rough leveling of uneven walls during construction or repair. The technology of plastering walls is used both outside and inside the building. Plaster allows you to level the surface of the wall and repair defects that have arisen during operation. Certain types of plaster allow you to create decorative layers on the walls. Dry building mixtures intended for rough plastering of walls and ceilings consist of cement and sand, or gypsum. Chemical additives added to the mixture make the plaster composition manufacturable; lighter, due to air-entrained agents; plastic, thanks to water-retaining components. For finishing, decorative plaster is used, which contains pigments, plasticizers, adhesive components, stone granules, and plastic. When performing the application technology, a given aesthetic pattern of the desired color is formed. For rooms with high and variable humidity and temperature, plasters containing silicone are used. After hardening, the composition remains flexible and tolerates high humidity and temperature changes.

Plaster

Source: https://kraski-net.ru/

Putties

The purpose of putty is to bring the surface to a smooth, mirror-like state, that is, it is intended for fine finishing. Putty, like plaster, is a mixture consisting of binder and filler, but the grain size fraction is much finer. Putty can repair small cracks and smooth out the roughness of the plastered surface. The composition is cement, gypsum, acrylic and polymer. Additives added to dry mixtures are similar to those added to plaster. In putty compositions, it is important to achieve a balance of viscosity and maximum plasticity. Each type of dry putty mixture is designed for specific surfaces. In practice, putty is applied to concrete, brick, and wooden bases.

Putty

Source: https://utepliteli-77.ru/

Dry adhesives

The adhesive mixture is a powder of a given size, consisting of cement, quartz sand and special additives that increase adhesive and water-repellent properties. Suitable for interior and exterior work. Depending on the purpose, dry adhesive mixtures are used for laying aerated concrete blocks, tiling, building insulation work, and installing parquet floors. Adhesives based on dry mixtures are perfectly applied to brick, concrete, cement-sand substrates.

Dry adhesives

Source: https://www.aliance.online/

Self-leveling floors

Self-leveling floors are a special type of screed, which, unlike the starting coating, has an aesthetic function. The layer thickness is 2-3 millimeters. An important feature of ready-made self-leveling floors is their resistance to abrasion and aggressive environments. This is the main difference from sand-cement coatings. Several types of mixtures for self-leveling self-leveling floors are used in construction:

• Polyurethane
• Epoxy
• Methyl acrylate
• Cement-acrylic

Technologies for using mixtures allow combinations of compositions to obtain coatings of specified properties.

Self-leveling floors are widely used in the construction of industrial premises, where increased reliability and durability are required; in residential premises, where priority is given to saving space, aesthetics and design; in buildings with high traffic capacity - offices, business and shopping centers, where there are requirements for wear resistance and originality of the coating; catering establishments and hotel and health resorts, where mechanical cleaning is carried out using aggressive detergents.

Self-leveling floors

Source: https://solnechnogorsk.tiu.ru/

Special blends

Special dry construction mixtures should be included in a separate group. They are designed to solve highly specialized problems. But the capabilities of the modern chemical industry successfully create promising multicomponent mixtures that can satisfy several purposes. For example, be plaster, waterproofing and adhesive for tiles or tiles. The only question is the cost and demand for such composites.

Specialized mixtures include compositions for waterproofing, for repair and restoration work and for insulating buildings.

Warm plaster

There are types of mixtures that are intended for internal and external insulation. It has a dual purpose: wall leveling and insulation. Warming occurs due to the presence in the mixture, in addition to the classical components, of expanded rock. It is obtained by heat treatment of mineral raw materials: perlite, vermiculite, expanded clay. Mixtures are produced with the addition of foamed fiberglass, quartz sand, and expanded polystyrene components. When choosing a dry mixture for insulating surfaces, you should pay attention to the area of ​​application, since not all mixtures are universal and are intended for use only in certain conditions - inside or outside the building.

Warm plaster

Source: https://kraski-net.ru/

Repair and restoration mixtures

Designed for repair and restoration of reinforced concrete structures. During operation, reinforced concrete structures are exposed to aggressive influences from various environments. As a result, the concrete composition loses strength and the reinforcement undergoes corrosion. To restore the strength characteristics of structures, a comprehensive concrete restoration system is used. It includes compositions for anti-corrosion treatment of reinforcement, mixtures for preparing the adhesive layer; mixtures for filling potholes, chips, voids; coarse or fine-grained mixture for concrete repair; polymer cement putty.

Specialized mixtures for repair and restoration work

Source: https://construction-engineer.ru/

Mixtures sealants

They are produced on the basis of cements that have high water resistance in the final form, with the addition of polymeric materials and additives.

• Penetrating waterproofing mixture. When the mixture is applied to the surface, the composition begins to actively penetrate into the base through microcracks and capillaries. During the process of filling cavities, a chemical reaction occurs between the components of the mixture and water. Insoluble crystal hydrates are formed, which clog microcavities and stop the capillary and diffusion movement of water. The more saturated the concrete is with moisture, the faster and deeper the crystallization process.
• Coating. It is applied to the surface in the form of a plaster composition, filling irregularities and voids. After hardening, it forms a stable water-repellent layer that prevents the entry of liquid and vapor into the base body.

Sealing mixture

Source: https://kamburg.ru/

Blend selection

The range of dry construction mixtures is extensive and includes many items. To make the right choice, you must adhere to a number of recommendations.

• You need to know exactly for what tasks the building mixtures will be used.
• When choosing a manufacturer, preference should be given to trusted companies that have proven themselves positively.
• Focus on price. Most likely, products of the middle and upper price level will provide the required quality and desired result.
• Before purchasing, it is important to pay attention to the conditions, shelf life and use of the dry mixture. Under no circumstances should you purchase expired goods or in violation of packaging and storage conditions.
• The guarantee of the quality of the dry construction mixture is the availability of service support from the manufacturer. Leading companies value their positions in the market and strive to improve them, including by providing support and advice to customers on the use of products.
• When choosing a mixture, it is necessary to understand the operating conditions of the created coating. Strictly follow the manufacturer's recommendations regarding application methods and operating modes.

Dry construction mixtures are designed to increase labor productivity, and in combination with high quality and decent results, they provide a significant economic effect, which allows you to repeatedly cover the costs associated with the use and cost of the mixtures.

tags: BUILDING MIXTURES, DRY MIXTURES

Marking of gypsum binders

Binder grade	Ultimate strength MPa at: compression bending	Binder grade	Ultimate strength MPa at: compression bending
G-2	1,2	G-10	4,5
G-3	1,8	G-13	5,5
G-4	2,0	G-16	6,0
G-5	2,5	G-19	6,5
G-6	3,0	G-22	7,0
G-7	3,5	G-25	8,0

For construction products and decorative parts, it is recommended to use gypsum grades G-2...G-7 of all curing periods and degrees of grinding. For plastering work, grouting joints and for special purposes, gypsum grades G-2...G-25 of normal and slow hardening, medium and fine grinding are used.

Binders of the highest category for construction products must have a strength not lower than G-5, the maximum residue on sieve No. 02 is no more than 12%.

2.2.2. Fundamentals of technology for gypsum and gypsum concrete products

Gypsum binders are used in the production of gypsum plaster, partition wall slabs (plaster) and panels, wall stones, parts, and gypsum dry building mixtures. Anhydrite cement is used for the construction of seamless floors, bases for finished floors (including prefabricated ones), in the production of lightweight concrete and artificial marble. Estrich gypsum is used similarly to anhydrite when constructing floors.

Plaster of Paris

– (gypsum partition boards) in accordance with GOST requirements are produced with a thickness of 80...100 mm and a length of 800 mm. The end and side faces are made in the form of semicircular grooves or grooves and ridges, filled with mortar when assembling the partitions. The slabs are made from gypsum dough and gypsum concrete mixtures with fillers from wood sawdust and fibers up to 3% by weight. The components are mixed with water in a gypsum mixer at a rotation speed of the screw blades of 600...1000 rpm. Products are molded on a carousel machine in paired sliding molds. The machine table rotates around a vertical shaft. In this case, each of the forms is installed in turn under the stirrer. In one revolution within 7 minutes the machine forms 56 slabs. During this period, the gypsum mixture should set and the products are pushed out of the molds. To ensure setting, the gypsum is mixed with warm water within 5…6 minutes (T=35…40 °C). To speed up the setting, 2...3% of secondary gypsum dihydrate is added to the composition of the mass. Molded products are dried in tunnel dryers with purified flue gases or heated air at a temperature of 100...120°C for 24...30 hours.

GKL – plasterboard sheets

are manufactured in thicknesses of 10...12 mm, widths of 1200...1300 mm and lengths of 250...3300 mm.
The gypsum mass from a mixture of gypsum, water, setting regulator (SDB, secondary dihydrate, NaCl) is fed from a propeller-scraper mixer to the forming table. The gypsum mixture is evenly distributed over the bottom cardboard strip. The edges of the bottom tape are bent upward, and then the top cardboard tape is glued to them under the forming rollers with liquid glass. The plasterboard tape moves along the setting conveyor to the cutting machine. By the time the tape is cut into sheets, the gypsum core has set. The sheets enter the tunnel dryer. The strength and durability of plaster sheets increases if, instead of sheets of cardboard, waste paper is used for reinforcement, introduced into the mixer in the form of paper pulp. Pressing technology is also used to produce gypsum products. This sheet plaster is produced under the name gypsum fiber sheets - GVL
. GKL and GVL are mounted along metal guide profiles using self-tapping screws.

Gypsum concrete panels

used for installing partitions in rooms with humidity up to 60%. They are made the size of a room, solid or with openings 80...100 mm thick, 3 m high and 6 m long. Gypsum concrete partitions are 80: cheaper than brick and 125% cheaper than reinforced concrete, have good sound insulation, gypsum, water, sand, coarse aggregate in the form pumice, tuff, fuel slag, expanded clay, agloporite, sawdust, fibers, flax fires. The panels are reinforced with aluminum wire or wooden slats. The disadvantages of the panels are fragility, reduced adhesion to reinforcement, creep, and low water resistance. Products are molded by casting or pressing, dried at a temperature of 105...130 °C for 18...24 hours. In construction practice, gypsum-based dry mixtures are used for finishing work.

Composition of dry mixtures

Dry building mixtures are a special set of components prepared for the production cycle. According to the technological map, they are strictly dosed and are intended to perform a certain type of repair and construction work.

The structure of a dry construction mixture necessarily includes a binder. Binder is the main component of the dry mixture. This is the connecting element that brings together all its elements. The main characteristics of the future mortar depend on the choice of binder. Gypsum, construction cement, and fluff lime can be used as a binder. To give dry mixtures special properties, various combinations of Portland cement and mineral powder, lime and cement, lime and gypsum, etc. can be used in their production.

To save binder and create optimal volume, manufacturers of dry building mixtures introduce neutral fillers (inert) into the composition - most often these are sand of different size fractions, granite chips, as well as special additives that give the compound the necessary properties, such as frost resistance, stability at exposure to high temperatures, water-repellent characteristics, etc. Components are added to the plaster mixture to prevent damage to walls by fungi, as well as components that impart plasticity to the plaster solution. Special additives for concrete are also used to give the coatings hardness and water-repellent properties. To add color, special additives are used - pigments.

The recipe for preparing the dry mixture is individual for each type and brand. The quality of dry mixtures directly depends on the accuracy of the recipe, the accuracy of dosing, and the thoroughness of mixing the components during its production. The slightest failure to comply with one of the points can significantly affect the quality of the resulting composition. That is why modern factories producing dry mixtures have long been using high-quality mixers, strain gauge weighing dispensers, using multi-component premix additives, etc.

It is worth noting that part of the responsibility for the quality of the mixture lies with the consumer. After all, even the most modern high-quality dry mixture can be ruined by improper mixing (kneading). The amount of water introduced into the solution is of great importance. An overdose of water sharply worsens the mechanical properties and adhesion characteristics of the future solution. The main reason for this is a violation of the water-cement ratio (if we are talking about the composition of dry mixtures with a cement binder). The temperature of the water is also important. Hot water can “kill” most of the modern additives included in dry building mixtures. That is why, before you start preparing the building mixture, you need to read the instructions (which manufacturers usually place on the back of the bag). And take this seriously.

Technical properties of the mixture “VOLMA-Layer”

No.	The name of indicators	Technical requirements
Water consumption, W/T	0,6…0,85
Beginning of setting, not earlier than, min
End of setting, no later than, min
Base temperature, degrees. WITH	+5…+30
Water holding capacity,%
Compressive strength, MPa, not less
Bending strength, MPa, no more	2,5
Consumption per 1 m2, kg	8…9
Recommended layer thickness, mm	5…30
Maximum layer thickness, mm

Today, a wide range of interior finishing tasks are solved using dry gypsum-based mixtures. The most common brands of dry construction mixtures based on gypsum include the brands “Vitonit”, KNAUF, “Plitonit”, “Yunis-XXI”, “Atlas”, “Starateli”, “Bolars”, “VOLMA”. Dry mixes of the KNAUF brand have proven themselves well. These are thin-layer (finishing) and thick-layer plaster mixtures, putties, and adhesives. For example, Rotband plaster (Rotband-Haftputzgips) is a universal dry plaster mixture based on gypsum binder. Designed for manual plastering of wall surfaces with a rough surface - brickwork, foam concrete indoors with normal humidity, including kitchens and bathrooms in residential premises.

Dry mixture based on gypsum

“VOLMA-Layer” is a gypsum plaster for manual application that does not require puttying. Contains mineral and water-reducing additives. Technical characteristics of the mixture are given in table. 2.2.

Application areas of mixtures

• In screeds. Branded cement-sand mixtures with modifiers and crushed stone as a filler are widely used in the construction of screeds (especially dry mixture M300).
• For leveling the coating under tiles, laminate, parquet or linoleum. The solution from dry mixtures is plastic, so a horizontal leveling layer 3-4 cm thick is quite easy to arrange.
• The walls are leveled using a plaster or putty mixture.
• External finishing of building facades also occurs using dry mixtures.
• Adhesive mixtures are used to lay tiles outdoors in outdoor swimming pools and are used when laying tiles on the plinths of buildings.
• Used as coating waterproofing to protect the basement of a house from moisture.
• When replacing cracked tiles, use a repair mixture that hardens quickly.
• Eliminate pinpoint water leaks. The leak stops within 5 minutes.
• Special mixtures are present in masonry mortars.

Recommendations for choosing a dry mixture depending on the type of room and design features of the base

The dry mixture for the floor is selected based on the design features of the floor base, depending on the type of finishing of the floor surface. The strength requirements for a screed installed on concrete under tiles, laminate, chipboard are lower than the requirements for a screed on a wooden floor. The latter should be much more resistant to fracture and have high wear resistance. In such cases, it is recommended to purchase a dry building mixture containing fiber fiber, since a low-grade screed may crumble or crack. In this case, additional reinforcement with masonry mesh will not be superfluous. When choosing a dry mixture for walls, they are guided by where the finishing will take place: outside or inside the building. The thickness of the leveling layer is also important (depending primarily on the verticality of the walls). The choice is influenced by the planned finishing of the surfaces. For rooms with a constant presence of moisture in the air, mixtures with a cement-mineral binder as a base are used. In dry rooms, a mixture with polymer binders is used. Since gypsum plaster strongly absorbs water, it is not suitable for exterior decoration and finishing of wet areas. It is better to level external walls with a dry mixture containing a lime modifier. Additionally, cement-lime plaster protects against the formation of fungus and mold on the walls. The dry mixture for masonry should guarantee the strength of the mortar when laying walls. Therefore, it is not recommended to use high-grade masonry mixture. This mixture produces heavy concrete, which, when hardened, is not elastic and very durable. A seam made from such a solution may crack when hardening. It is necessary to select balanced masonry mixtures for medium mortars.

On our website you can always choose and purchase building mixtures wholesale and retail at the most attractive prices.

Basics of construction air lime technology

Construction lime is a group of mineral binders obtained by firing below the sintering temperature of calcium-magnesium carbonate rocks in shaft or rotary kilns. During the firing process at 900...1000 °C, limestone undergoes dissociation:

CaCO3 = CaO + CO2

Crushed limestone with a particle size of at least 20 mm is loaded into the shaft furnace from above. Natural gas is used as fuel. When fuel burns, upward flows of combustion products are sucked through the raw material and cause dissociation of carbonate rocks. In the lower zone of the kiln, the lime is cooled by the air entering the shaft and is shipped at a temperature of 50...100 °C. Rotary kilns are used for firing raw material fines - particles with a particle size of 5...20 mm. They are more productive and require less capital investment, but due to heat loss they are characterized by increased fuel consumption.

The product of calcination of limestone is lump porous material - lump quicklime - boiling pot

.
The interaction of quicklime with water is called slaking
:

CaO + H2O = Ca(OH)2+ Q.

Extinguishing is accompanied by the release of heat. The slaking product is slaked lime, a light fluffy powder of Ca(OH)2. Slaking with excess water produces lime paste or lime milk.

Lime hardening

in air consists of the evaporation of water, the crystallization of calcium hydroxide and its carbonization under the influence of atmospheric carbon dioxide:

Ca(OH)2 + CO2 + H2O = CaCO3 + H2O.

The hardening process of lime proceeds slowly, the strength of lime mortars is not great. The percentage of total content of CaO and MgO in lime is called lime activity

(A). In calcium air lime the proportion of MgO does not exceed 5%. Based on activity, calcium air lime is divided into grades: Grade I – A ≥ 90%, Grade II – A ≥ 80%, Grade III – A ≥ 70%. In air, quicklime quickly carbonizes and loses activity. In slaked form, it can be stored for a long time without losing its activity. Working with lime requires special safety measures, as it is an alkali.

Dry building mixtures: use and varieties

A whole army of tourists travel and travel to different countries or even to historical places in their own country to look at centuries-old buildings and admire their beauty and durability. They existed for many centuries and retained their solidity. How did our ancestors build? How conscientiously did they lay the stones and bricks? What mixture did they use to hold their buildings together? Apparently, they knew some special secrets of combining different materials when preparing the fixing mixture. Not only archaeologists, but also many other specialists have been studying the composition of these mixtures for many years in order to discover their secret.

Any construction, be it an ordinary house or a multi-story building, sets itself the same task - to fasten all the parts and blocks of the building as firmly as possible so that they stand the test of time. In addition to the construction of external walls, interior finishing work is also carried out, and special finishing and fastening materials are also required here.

The entire construction process significantly depends on the quality of the fastening material.

The use of dry building mixtures today

Until recently, and even today, when carrying out various types of construction work, a mixture of cement, sand and water holding stones and bricks together is prepared directly at the construction site according to rough calculations. The result is an uneven distribution of the strength and elasticity parameters of the coating over the entire surface, plus unfavorable weather conditions that constantly test the outer surface, and as a result, cracks form, which over time can turn into a problem.

Now ready-made dry construction mixtures for various stages of construction and finishing work have appeared on sale. The industrial production of such special products ensures a special selection of specific components suitable for solving various types of problems during the construction and renovation of premises. We are seeing a real boom in the sale of such mixtures. Naturally, it is very difficult for an inexperienced customer to understand all this diversity, especially when the contractor who took on the work advocates for traditional methods of construction the old fashioned way. One can’t help but think that he is somehow interested in this, either because he does not have the latest information about new products on the market, or for some of his own financial reasons. But in any case, the last word and decisive choice, of course, remains with the customer. And here he must seriously think about and present his goal, and also take an interest in the state of the issue today. The wide range of offered assortment and possibilities is so attractive that there is a desire to build and repair, if only there was money.

Carrying out construction work using dry construction mixtures

If you start construction with a pit dug for the foundation, then you need special mixtures for concrete and reinforced concrete work. Such mixtures must have great strength and be resistant to moisture contained in the soil.

Then the walls are erected and dry mixtures of a different composition are used here, containing gypsum, lime, cement, and some kind of porous fillers. These mixtures can be more or less plastic in order to better and more evenly cover the surface of the walls, seal irregularities or cracks, and ensure the resistance of the coating to temperature changes. Mixtures are used for the primary coating of walls, they are called starting and for secondary coating, decorative coating, the so-called finishing mixtures.

The foundation and walls are the basis of any room and the use of high-quality material is more than advisable here.

The choice of materials and dry mixtures for interior finishing work around the house is especially wide. It is very important that these mixtures contain adhesive and astringent mineral components. The presence of a certain amount of certain chemical elements ensures rapid drying of the coating and setting of the mixture solution. The durability and quality of further work depends on them. Such plaster mixtures are used to level the internal and external surfaces of walls, seal various cracks, they are also good for decorating them, covering them with various kinds of textured details.

Types of dry construction mixtures

• Leveling - for leveling ceilings and walls, sealing cracks, depressions, sinks (putty, plaster).
• Facing.
• Floor - for installing floor elements.
• Repair - restore the performance indicators of stone, concrete, reinforced concrete structures.
• Protective - form a protective coating on the surface. They are also called sanitizing.
• Masonry - for laying walls and partitions.
• Assembly - when installing building structures and products, fastening anchors, etc.
• Decorative - give a relief texture, a certain color, etc.
• Waterproofing.
• Thermal insulation.
• Primers - to increase the adhesion strength between the base and the coating.
• Soundproofing.

Advantages of dry construction mixtures

• Cost-effectiveness of dry construction mixtures.
• Excellent adhesion performance with various types of surfaces.
• Use for interior and exterior work.
• Long shelf life.
• Dry building mixtures are absolutely safe for human health and the environment.

Thus, we can say that dry building mixtures greatly facilitate and optimize the grueling process of construction and repair, ensuring its quality and durability.

CATALOG OF DRY CONSTRUCTION MIXTURES

Sincerely,

Team of the Faculty of Construction Materials

#RDS-Academy

Technology of products based on lime binders

In construction, lime is used for the preparation of whitewash compositions and in the production of silicate products

(sand-lime bricks, silicate concretes, heat-insulating cellular silicate products), masonry and plaster mortars, including dry construction mixtures.

In 1880, the German scientist Michaelis found that under autoclave conditions (P = 0.8 MPa, T = 180 °C) strong and relatively durable products can be obtained from lime-sand mixtures. The chemical interaction of lime and quartz sand under autoclave conditions leads to the formation of calcium hydrosilicates. This chemical process underlies the hardening of lime in silicate products:

Ca(OH)2 + SiO2 +( n-1)H2O = CaO SiO2 nH2O.

The raw material mixture for sand-lime brick contains 92...95% quartz sand, 5...8% lime and about 7% water.

Sand-lime brick manufacturing technology

consists of mining sand and limestone, producing lime, grinding lime together with quartz sand in a ball mill, preparing a lime-sand mixture, and slaking it. pressing brick at a pressure of P-15...20 MPa and steaming it in an autoclave. The lime-sand mixture can be slaked in a continuously rotating drum with live steam at a pressure of 0.2 MPa, or after mixing with water in a mixer, slaking occurs when it is kept in silos for 6...9 hours. Brick molding is carried out in three-position semi-automatic turret presses at a pressure of 15...20 MPa. The pressed raw material is sent on trolleys to an autoclave, where it is steamed under a pressure of 0.8...1.6 MPa for 10...14 hours.

Sand-lime brick is produced in seven strength grades: 300,250,200, 150, 125, 100, 75; frost resistance - F50, F35, F25, F15. The average brick density is 1800…2100 kg/m3. Sand-lime brick is used for the construction of walls and partitions. It cannot be used for laying foundations, as it is not waterproof, or for laying stoves and chimneys, since it is not heat resistant.

Silicate concrete

obtained from a mixture of quartz sand 70...80%, ground sand with a specific surface of 200...250 m2/kg - 8...15% and ground quicklime with a specific surface of 400...500 m2/kg -6...10%.

The raw material mixture is prepared in forced-action concrete mixers, and the products are molded on vibrating platforms. After holding, the products are hardened in autoclaves according to the following regime: 2 hours – pressure rise, 8…9 hours – isothermal steaming at this pressure, 2…3 hours – pressure release. The compressive strength of products is 15...40 MPa, and with vibration rolling - up to 60 MPa. The disadvantage of the products is increased deformability. The elastic modulus is 2 times lower than that of cement concrete. Dense silicate products are used for dry and normal operation in residential, industrial and public buildings, with the exception of foundations.

Cellular autoclave

silicate concretes -
foam silicates and gas silicates
are produced by introducing stable technical foam or gas-forming agents into the formulation. Cellular silicate concrete can have a density from 300 to 1200 kg/m3 and a thermal conductivity coefficient of 0.06...0.38 W/mK. These are lightweight concretes for thermal insulation and thermal insulation and structural purposes. Cellular concrete is produced with a strength from 0.8 to 15 MPa.

What does the dry mixture consist of: base

The powder includes a special set of substances that ensure easy preparation of a universal solution under any conditions by adding water. According to the technological map, powders are strictly dosed and used for capital construction, finishing, and repairs.

The structure of the composition of dry construction mixtures includes several components. Each component affects the basic additional characteristics of the dry mixture. The solution necessarily includes a base - astringent dry mixtures. The foundation collects and integrates all other components. The basic properties depend on the type of building binder material.

The Monolit dry building mixtures plant uses the following basics:

• gypsum;
• cement;
• lime.

Minerals only work when mixed with water. Binders are present in different proportions. The proportions are affected by the purpose and brand. The remaining components of dry mixtures are needed to improve basic qualities in order to expand applicability.

Cement M500-D0 (CEM I 42.5N)

Price from 200 rub.

More details

Gypsum G5 - G7 АΙΙ

Peculiarity

special strength, stability of characteristics

Fine
grinding
High degree of whiteness

Price from 230 rub.

More details

Slaked lime (hydrate)

Compound

hydrated Ca (OH)2
Type
slaked
Grinding
fine
Whiteness
high degree

Price from 200 rub.

More details

Quicklime

Type

fired, active
Grinding
fine
Whiteness
high degree

Price from 200 rub.

More details

White cement PORTLAND CEMENT EN 197-1-CEM I 52.5 N

Brand

600 D0
Manufacturer
Sinai White Cement Company SAE, Egypt

Price from 200 rub.

More details

Technology of magnesium binders and products made from them

Magnesia binders are air binders obtained by firing at a temperature of 700...800 ° C and grinding natural magnesite or dolomite in shaft or rotary kilns. By firing magnesite at a temperature of 700...800°C, caustic magnesite is obtained:

MgСO3 = MgO + CO2.

Caustic magnesite is obtained by firing dolmitaite at a temperature of 650...900°C:

MgСO3CaСО3 = MgO CaCO3 + CO2.

For mixing, not water is used, but concentrated solutions of FeSO4 or MgCl26H2O salts - bischofite. The dosage of bischofite by weight should be 33...38 MPa. After 28 days, the strength of the artificial stone is 20...60 MPa; in the case of using caustic dolomite, the strength does not exceed 30 MPa.

During the hardening process, magnesium oxychloride 3MgOMgCl26H2O is formed and Mg(OH)2 crystallizes.

Magnesium binders are used for the production of concrete with organic fillers. When wood shavings are used, heat-insulating fiberboard is obtained, and when sawdust is added, xylolite is obtained, which is used in the construction of walls and floors. In combination with inorganic fillers, plaster mortars, artificial marble slabs, stair steps and window sill slabs are obtained. Products are formed by pressing, after which they are sent to drying chambers. Magnesium binders are classified as air binders. Products made from magnesium binders must be protected from moisture and used in rooms with a humidity of no more than 60%.

Fillers in dry building mixtures - their need and distribution

For the manufacture of small architectural forms and garden decor such as gazebos, sculptures, vases, garden furniture, barbecues and barbecues, fire pits, various forms of artificial stone, garden paths and platforms, retaining walls, small buildings, etc., are used cement mortars of various compositions, which necessarily include some passive and/or active fillers.

When producing dry mixtures, specialists meet the requirements of certain standards, including those for fillers.

In our case, when working in the garden, it is more important to use practical advice and the experience of experienced craftsmen, which we take into account.

Previously published articles on the pages of kamsaddeco.com (in particular here) have already presented the main parameters and properties of additives and fillers, as well as their volumetric quantities in mixtures for various applications.

Fillers included in dry construction mixtures include: quartz sand, slag sand, fly ash, ground quartz, mountain sand, brick chips, marble and dolomite flour, chalk. Decorative compositions also include vermiculite, fine marble chips, ground glass and other components as fillers.

Fillers should contain as few impurities as possible that impair the adhesion of the solution. So clay in sand in an amount of 1.0-1.5% impairs the adhesion of the glue by about two times.

When making plastic concrete for decorative forms, crushed stone is rarely used. In the garden, it is included in concrete for the construction of foundations, ponds, and some foundations, for example, for concrete figures, platforms, paths, retaining walls or artificial rocks.

For the manufacture of garden decor, the concrete usually contains fine granite chips or washed screenings.

Selection of fillers for the mixture

Now there are a few more important points in the selection of fillers included in dry building mixtures. They must be taken into account when dosing independently.

In relation to fillers, experts use the concept of “granulometric composition” or “fineness modulus”. What are these characteristics for?

The previous chapter indicated that we should try to prepare the optimal composition of the dry mixture in order to save money and obtain maximum mechanical performance.

To do this, it is necessary to select fillers in such a way as to ensure their dense packing in the cement mixture. The less free unfilled space remains, the better the performance will be. At the same time, we save cement and can replace it with a higher quality one. Expensive polymer and chemical additives are also saved. It is very important to take into account the porosity of the fillers. And most often we encounter this when making artificial stone and decor from hypertufa.

Porous filler included in dry construction mixtures

Sometimes some people complain that their products fall apart after just a few years of use. Usually, when preparing a solution, water is poured “by eye”. Few people warn that one should not rush and wait. The porous filler (expanded perlite, peat or moss) should be completely saturated and stop taking water from the solution. It is necessary for complete hydration of the cement.

This point must also be taken into account when adding dye to dry mixtures for coloring concrete. For example, yellow iron oxide pigment consumes significantly more water than others.

At the same time, the feature of loose fillers can be used as a positive property in the manufacture of large decorative surfaces. The goal here is to partially or completely replace expensive cellulose ethers. This procedure will increase the open cure time without the use of a waterproofing film.

Another very important parameter that affects the quality of the dry mixture is the specific surface area of ​​the filler.

The finer the filler, the greater its specific surface area. In this case, more water is required to achieve sufficient mobility of the solution. If, for example, quartz flour is added to the mixture, but the amount of water and cement remains the same, then cracks cannot be avoided.

♦ Large specific surface area of ​​the filler requires additional amount of binder.

Description and features of dry construction mixtures

Dry building mixtures are a counterbalance to measuring and mixing components yourself. Plaster, for example, contains cement, limestone, kaolin, sand and glue. Sometimes all the elements are needed, and sometimes only 2-3. In compositions for exterior finishing, for example, gypsum is unacceptable - it absorbs moisture.

The dry construction mixtures plant supplies goods with constant quality characteristics, number and weight of components. This saves time - an important resource in the era of globalization.

By purchasing separately and mixing the components, you lose more than you save. In addition, purchasing ready-made mixtures eliminates miscalculations in proportions. You only need to measure the amount of water poured.

They also save on cars. Their order is necessary when purchasing an already diluted mixture. It is poured into tanks and transported to sites, like cement. The latter also comes in dry form. A bag of the mixture costs around 400 rubles and is convenient for small volumes of filling.

What are the dry mixes?

What applies to mortars: This is a wide range of mortars that are sold in powder form. To prepare a high-quality solution of the desired consistency, simply dilute the powder with water. The proportions are indicated in the table of dry mixtures on the packaging.

The powder can be disassembled into individual components. It is based on astringents that are responsible for the basic qualities:

• cement;
• gypsum;
• lime.

Each brand of dry construction mixtures contains one main binder. A certain filler is added to the main binder. The type of filler depends on the purpose.

Often dry construction powders contain modifying additives. They change the basic characteristics, giving additional improved properties. Most contain polymers, which affect the strength after drying. Some polymers improve adhesive properties. They are added to enhance hygroscopicity, wear resistance and resistance to mechanical stress.

All additives are needed to regulate hygroscopicity, strength, frost resistance and enhance other qualities. To prevent separation, a cellulose ether thickener is introduced. For frost resistance, mineral salts are added. To make the solution more plastic, water inhibitors are used.

In addition, the types of dry construction mixtures differ in grain size, name, and brand. Classifications of dry mixtures are prescribed by GOST.

Classification of dry mixtures in modern construction

First you need to know that such products are divided into two large groups depending on the main component:

• with minerals in the composition;
• with a mineral-based binder.

Connecting elements, in turn, are divided into:

• cement;
• plaster.

Each mixture may contain a special additive. Taking this feature into account, they are:

• thermal insulation;
• fire resistant;
• frost-resistant;
• thin-layer.

Based on their functional purpose, products are divided into the following types:

• leveling;
• floor;
• waterproofing;
• load-bearing;
• installation;
• decorative;
• protective;
• masonry.

According to the method of application, dry mixtures are divided into adhesive, plaster and putty. Let's look at each option in more detail.

• Primer Bergauf Beton Kontakt, 14 kg 1030₽
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• Primer Ceresit CT17 PRO, 10l 684₽

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• Primer Ceresit CT19 concrete contact, 15 kg 1225₽

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What applies to building mixtures

Mortar building materials are classified by type and application:

• levelers: based on gypsum, lime, cement; used for leveling and eliminating defects;
• plasters: based on coarse-grained materials; are used for plastering indoor walls and facades;
• putties: fine-grained compounds for the finishing stage, can be used on the inside or outside of the building;
• screeds for leveling and filling the floor;
• grout for seams, joints, cracks;
• repair: cement-based, used to restore geometry, repair;
• assembly: for laying brick, stone, concrete and reinforced concrete blocks;
• adhesive: for fixing elements on the floor, walls, ceiling made of different materials;
• self-leveling: for filling and leveling the floor.

Differences between dry mixes based on their intended purpose. Each solution has a certain set of fillers and modifiers that change the properties of the main binder. The result is a solution of the required consistency with a set of its own qualities.

Under the “Monolit” brand of dry concrete mix, modern dry building mixtures are sold in sealed packages that protect the composition from moisture. The price depends on the brand of building mixtures and functionality.

Pros and cons of dry construction mixtures

When working with SSS, you need additional equipment. So, a construction mixer for dry mixtures . You need a container in which to dilute the solutions. For a construction team, purchasing equipment is a quick return on investment.

If you purchase equipment for minor, independent repairs, the use of SSS may entail expenses unforeseen by an unprofessional eye. Sometimes, it is more profitable to hire finishers with a ready-made inventory and skills in handling it.

The relative disadvantages of SSS include their range. Consumers are confused about the names and specializations of mixtures. Without knowledge of the market, there is a high risk of purchasing waste, low-quality material.

Otherwise, dry formulations are attractive and, at times, irreplaceable. For example, no renovation is complete without plaster. This means that you can find more than one review about SSS on the Internet.