Clay plaster. Advantages and disadvantages. Types of finishing solutions. The choice of the type of composition and instruments. Preparation of the mixture, checking the level of plasticity and application

If the clay is relatively clean, you can not wipe it dry, but remove large impurities and soak immediately. It is best to use an old bathtub or a wooden box upholstered with metal sheets for this purpose. To make the raw material well wet, it is covered with layers of 120-150 mm, each of them spilled with water. While standing, you can periodically stir the mineral with a shovel.

Clay mortar for masonry ovens proportions, materials and preparation procedure

What material is the progenitor of cement and concrete mixtures? Every stove-maker knows the answer - clay. Until now, it is an indispensable material for masonry. The use of clay mortar when laying bricks and fireplaces is due to several factors:

• Chamotte clay with natural kiln firing acquires the properties of a brick. That gives high rates of coupling of the entire structure.
• High thermal stability. After being treated with fire, the clay actually turns into a ceramic stone. It is able to withstand high thermal loads without significant damage.

However, in order to achieve the above, when preparing the solution, it is necessary to follow a number of rules and recommendations.

Clay types

First you need to decide on the method of obtaining clay. For residents of the private sector, you can get it yourself. The depth of the clay layers is low up to 1 m. But at the same time, its composition should be taken into account - not every consistency is suitable for the solution.

In addition to this method, you can purchase prepackaged fireclay clay already prepared by the factory.

The main indicator for clay is its fat content. For laying stoves (for example, a Russian stove), it is necessary to use medium fat clay. If this indicator is exceeded, then during firing irregularities will appear and the structure of the layer will be disturbed. A mortar made of oily clay is convenient for masonry - it has good adhesion characteristics and fits tightly on the brick surface. However, its use is not recommended anyway.

Preparation

The so-called "skinny" clay has a dense structure and it is necessary to apply certain physical efforts to create a high-quality homogeneous masonry.

The fat content can be balanced by the sand content. To determine the proportion, you can conduct a small experiment:

• Divide a small amount of clay into 5 parts. One of them does not mix with sand, and the rest are 1/4, 1/2, 1 and 1.5 parts, respectively.
• Knead each of them separately to a plastic state, make flat rounded blanks.
• After final drying, the quality of the mortar can be determined. If there is too much sand, the workpiece will crumble. If it is not enough, then the surface will be covered with cracks. It is optimal if the composition of the workpiece remains homogeneous and does not become covered with cracks.

After that, it is necessary to carry out the process of cleaning the clay from foreign impurities. For this, a sieve with a mesh size of 3 * 3 mm is used. In addition to this method, you can rinse the clay. For this, the container is installed at an angle of 4-8 degrees. Dirty clay is loaded into the upper part, and water into the lower part. Using a small spatula, wash the clay with water until a homogeneous solution is obtained in the lower part. The resulting solution is poured into a separate container.

When the required amount of material has been received, you can start making the solution.

Preparation of the solution

Before starting work, the clay must be soaked. To do this, a small layer of clay is poured into a large container, which is filled with water above the solution level. Then the next layer is applied and the procedure is repeated. After a day, the solution is mixed until smooth.

Solution recipe

Clay composition for masonry consists of three main components - clay, sand and water. The latter must be necessarily pure, without impurities and mineral additives. It is better to mix the composition in a bath, trough, tub, metal tank. To grease the oven, you can prepare a small amount of the composition in an ordinary bucket.

Usually, for the construction of the furnace and the foundation, they use not simple, but chamotte clay, which has high heat resistance. A standard clay-sand mixture is used for plastering the oven, but after adding salt, it is also suitable for the main masonry. Most often, a solution is made from 1 part of clay (simple or chamotte) and 2-3 parts of sand. The procedure for preparing the composition will be as follows:

• mix well the already prepared clay mass with a shovel, and then with a construction mixer;
• little by little sand is introduced, periodically stirring with a mixer and monitoring the homogeneity of the mass;
• add water in portions, bringing the mixture to a creamy texture;
• add salt to strengthen the future masonry.

Ratio with water

Typically, 75% dry matter requires about 25% water. In any case, the amount of liquid is determined empirically in a particular situation. It is important that there are no calcium carbonate impurities in the water, otherwise the substance will appear on the walls of the furnace and spoil its appearance. Similar problems will arise if the water has increased hardness due to the content of other impurities. Rainwater is best suited for preparing masonry.

Checking the quality of the composition

Before work, the finished mixture must be checked for the degree of plasticity and adhesion. To begin with, gain a little mass on a metal spatula and tilt the tool down. The high-quality compound slides off the spatula easily. After that, the clay mixture is applied to the brick with a layer of 7-8 mm, pressed on top with a second brick.

The excess of the squeezed out solution is removed so that the seam is no more than 4-5 mm. Leave the "masonry" to dry for 40 minutes, then evaluate the adhesion force. Take the structure by the top brick, raise it so that the bottom brick hangs in the air. If it does not come off, then the composition has a high degree of adhesion and is suitable for work.

To assess the correctness of the consistency of the finished mass, the following experiments are performed:

1. A spatula or trowel, previously soaked in water, is dipped into the mixed solution. If the composition sticks, then it is too greasy and requires the addition of sand.After the introduction of a new portion of sand, the mass is mixed again, and the check is repeated. Thus, they act until a composition with the desired consistency is obtained.
2. It happens that protruding water appears on the surface of the solution. In such a mass, the clay is too low in fat content. You will have to add a little mineral with a high fat content and mix the composition well. The same is done if the mixture does not adhere at all to the spatula due to the reduced plasticity.

The solution has dried up - what to do

To prevent drying, the clay paste is stored under a lid or covered with a wet cloth. But even with partial solidification, the solution can be returned to plasticity (only if there is no cement in it).

It is broken into pieces with a hammer, poured with water, left to soak for 24 hours. You can also shred the material with a wooden rammer. A day later, the paste is mixed using a construction mixer. If there is too much water in the composition, it is scooped out after settling or drained by tilting the container.

Specifications

The composition of such a solution necessarily includes cement, sand, slaked lime and water.

It is worth paying attention to the fact that it is necessary to add slaked lime. Otherwise, the quenching reaction will begin in the solution itself when water is added, and bubbles, forming already inside the solution, will lead to cracking of the plastered surface.

This process of bubbling will lead to deterioration in the quality of the solution and to brittleness after it dries.

Building mixtures, their composition and properties are regulated by various GOSTs. This is necessary for the standardization and regulation of building codes. GOST 28013-98 is the main regulatory legal act governing the technical requirements for mortars and materials included in the composition.

This standard also includes the characteristics of quality indicators, acceptance rules and conditions for the transportation of ready-made solutions. It contains the qualitative and quantitative characteristics of masonry mortars, materials for plastering and for interior work, used in various operating conditions.

Paving stones and paving slabs

The use of clay as an additive in mixed cement slurries along with diatomaceous earths and commonly used lime. As a first approximation, it can be assumed that the content of clay by weight in relation to cement should not exceed 1: 1 - 1.25: 1. With a larger amount of clay addition, the quality of solutions in terms of their frost resistance and softening coefficient can significantly decrease, why at present it is still impossible to judge the suitability of such mortars for masonry. A large number of tests carried out did not reveal any negative properties of cement-clay mortars, which could affect the judgment about the possibility of their use. On the contrary, the tests proved, within certain limits, the valuable qualities of cement-clay mortars, not to mention the fact that in most cases their cost is lower than similar mortars with other additives. However, the quality of the clay used, apparently, still plays a significant role, since different clays gave quite different results in our experiments. In particular, clays with a high organic matter content gave the worst performing solutions. Different clays have shown the best results in different test cases and for different characteristics. However, in most cases these best indicators were related to the cases of the introduction of brick clays into the solutions. Despite the significant difference in the chemical composition of the clays we use, no definite relationship between the quality of the resulting solutions and the chemical composition of the clays has been established at the present time. This should, apparently, be the subject of further research in this area.

However, already now it is possible to outline some ways to assess the quality of clays and compounds found in them, which can have a negative effect on the properties of cement-clay mortars. Clays, generally speaking, are so diverse in their mineralogical and chemical composition, this circumstance gives some researchers the opportunity to assert about “the presence of as many varieties of clay as deposits are examined” (G. Zalmang). In addition, the layered nature of a significant part of the occurrence makes the composition of the clay very variegated even in the same deposit. Therefore, the choice and use of clays in mixed solutions should be treated with great caution. Possible impurities to clay that can have a certain effect on the strength and durability of a mixed solution over time include the following, which are often found in them: a) sulfides - pyrite and marcasite; b) organic substances (plant tissues, bituminous substances, carbon, humic substances, in particular, humic acids; c) some easily soluble salts in the form of iron sulfates (melanterite), calcium (gypsum), magnesium (epsomite), potassium and sodium, sodium chloride and magnesium, soluble silicates of alkali and alkaline earth metals, chlorides of alkali metals.

Influence of pyrite

Pyrite in clay is usually found in the form of yellow grains with a metallic luster, cubes and flat rosettes visible to the naked eye. However, in the so-called alum clays, pyrite is also contained in a finely distributed state, and in this case it cannot be removed from the clay even by elutriation. According to Rice, pyrite can be found in almost every deposit, but in clays lying near the surface of the earth, it is rarely found in a stable form, since in the open air it quickly transforms into iron sulfate, and then into limonite (2Fe2Q3 3H2O), which is for mixed solutions, according to all available data, apparently harmless. However, when pyrite and marcasite decompose, sulfuric acid is released, forming sulfates with calcium, magnesium or iron carbonates contained in the clay. It should be noted that usually clays containing pyrite or marcasite are discarded during the production of ceramics and go to the dump. In any case, the clay before its use should be examined for the content of pyrite in it. Humic acids are part of humic substances, soluble in alkalis. According to Sven-Auden, one can generally distinguish:

a) humic acid, insoluble in water, black-brown; b) peat, water-insoluble, yellow-brown, c) fulvic acid, water-soluble, light yellow.

Humic substances, in turn, are divided into humic acids, humins, which dissolve in strong alkalis only after long boiling, and humus coal, which is completely insoluble in alkalis. When heated, humic acids also transform into an alkali-insoluble state. The chemical structure of humic acids remains generally insufficiently elucidated, however, the presence of the COOH group in them is considered proven. The presence of humic acids can be assessed in terms of the concentration of hydrogen ions. According to prof. Shvetsov, it can generally be considered that acids containing only the carboxyl group COOH do not have a particularly harmful effect on cement mortars when they are added to the mixing water. However, in view of the insufficient clarification of the chemical structure of humic substances and acids, the question of the nature and degree of their possible influence must still be the subject of systematic research.

The absence of a decrease in strength when mixing Portland cement on bog water containing humic substances and, in particular, humic acid, was observed by a number of researchers. D.Abrams in 1924 published the results of experiments on studying the strength of Portland cement mortars (in terms of 90 days to 2 1/2 years), on the basis of which it can be established that there is no significant decrease in the strength of mortars mixed in swamp water. Engineer Speransky, a series of experiments with natural and artificial waters containing humic substances, also showed the possibility of using them for mixing cement slurries. In these experiments, the studied peat waters ranged from 4.6 to 6.3, while the oxidizability ranged from 11 to 50 mg of oxygen per liter of water. In clays, according to Zalmang, the content of humic substances is usually in the range of 0-0.5% at a pH of 7.1 to 4.8; only in highly contaminated clays, which are mostly dark gray or brown-black in color, the content of humic substances reaches 2-2.5% at a pH value of 6 to 7. In the above experiments, Ing. Speranskii observed (in terms of up to 90 days) even a slight increase in the compressive strength of samples mixed with contaminated water, compared with samples mixed with distilled water (when all samples were stored in ordinary pure water). The absence of a serious effect of humic substances introduced during mixing of Portland cement on the strength of solutions can be explained by the presence of an overwhelming mass of cement in comparison with the amount of reagents introduced and neutralized by cement.

Some observed increase in strength, in relation to the general data of prof. B.G. Skramgaev and G.K. Dementieva, can be explained by some increase in the efficiency of hydration from the action of acids. Thus, it can be considered that humic substances and acids, if found in the mixing water, are unlikely to have a serious negative effect on the strength of mortars for masonry. Nevertheless, in the experiments, the clays with organic impurities showed the worst results and a tendency to some drop in strength in the long periods of hardening. However, for clays with a high organic matter content, Mache's experiments below provide measures to reduce or eliminate the hazard from the introduction of humus-containing clays.

In his experiments, Mache investigated the effect of the introduction of humus-containing chernozem on the strength of plastic cement slurries. The humus content in chernozem, determined by the method of M. Pietre, was 11.7%.

Considering from this point of view the influence of the presence of humus, it is possible to think that solutions with clays containing organic substances can be protected from the influence of the latter by introducing additional alkali, in particular lime. Hence, it should be assumed that the three-component solutions proposed by prof. V.P. Nekrasov (cement-lime-tripoli or cement-lime-clay), in some cases (the introduction of small amounts of lime when using raw clay and raw tripoli) from this point of view can give higher strength indicators than two-component cement-mixed mortars.

Along with humic substances, organic substances can also be found in clay in other forms: a) in the form of plant tissues (leaves, stems, roots, pieces of tree trunks), which can be easily removed from the clay during its preparation; b) in the form of organic substances of a bituminous nature, the effect of which on the quality of the cement slurry can be considered harmful only in rare cases (for example, in a very harmful form of brown coal); c) in the form of solid carbon in modifications similar to anthracite, which should not be considered harmful.

Since a significant content of this kind of organic matter is characterized by a grayish, bluish-gray and black color of clay, and sometimes by visible inclusions, it is necessary to refrain from using such clays for mortars. Clays of a different color, it would be desirable to check for the content of organic substances in them and establish the degree of acidity by determining the pH value (until the development and verification of simpler research methods).

It should be noted that by calcining the clay at a red-hot temperature or prolonged heating at a temperature of about 250 ° (for example, when drying before grinding), a significant part of the organic matter can be freed. In this regard, it should be noted that, apparently, the use of clays activated by calcination, as suggested by the aforementioned instruction of V.P. Nekrasov (1933), may be appropriate and beneficial in a number of cases. The most dangerous impurities in clay for cement-clay mortars can be, in addition to organic substances, easily soluble salts. Organic substances can directly cause a slight decrease in the strength of the solution, while the presence of soluble salts can manifest itself over time and lead to the subsequent weathering of the solution due to the phenomena of salt migration. The blown out of building materials is usually understood as their loss of strength and partial or complete destruction under the influence of atmospheric and other factors. The phenomena of weathering of mortars in general, to one degree or another, are relatively common, and the main reasons for such weathering can be divided into two most important categories:

1) Poor mixing of the mortar, leading to (the presence of weakened areas, weathering under the influence, mainly of the action of frost; with poor mixing of the solution, reliable and complete adhesion of the masonry elements cannot be carried out. In the absence of proper adhesion, cracks and damage easily occur in the brick wall even from insignificant precipitation of the basement These cracks are the centers of propagation of weathering phenomena under the influence of the subsequent ingress of water into such cracks and their freezing.

2) Weathering due to chemical and physical influences takes place, in particular, in the presence of solutions of sulfates, carbonates and chlorides in the components. Of the above possible soluble salts, with respect to the weathering phenomenon, the most harmless is calcium carbonate, followed by calcium sulfate and potassium sulfate. The most dangerous salts (in this respect are sodium sulfates, for example, Glauber's saline (Na2SQ4. 10H2O), and magnesium sulfates. The latter salt is especially dangerous in combination with potassium sulfate, since the resulting triple salt (K2SO4. MgS04. 6H2O) contains significant amount of water and crystallizes with a significant increase in volume, even greater than during the crystallization of sodium sulfates.

In sulphate clay, gypsum is most often found, and according to Dawit and a number of other researchers. the content of sulfuric acid salts in clays varies greatly and can be quite significant. For example, according to Nirsch. the SO3 content in the clay of the same deposit ranged from 0.016 to 0.271%. It should be noted, however, that quite often the SO3 content in fired brick reaches 0.2–0.3%, which is explained by the use sometimes for firing coal with a significant content of sulfur compounds. Especially often, a high S03 content occurs in relatively weakly fired bricks. Thus, the weathering of the masonry under the influence of sulfates can also take place due to their presence in the piece elements of the masonry. In addition, it should be noted that the hardened cement used for masonry may also contain a number of compounds that contribute to the appearance of efflorescence. The destruction of the solution in the seams of the masonry from the phenomena of efflorescence generally occurs as follows: moisture introduced into the wall together with the solution dissolves the available soluble salts. As the masonry dries, soluble salts move from the surface towards the outer surfaces of the wall. Subsequently, soluble salts approach the wall surface, where they crystallize in the pores of the solution and on the surface.Since this crystallization occurs for a significant part of soluble salts with a large increase in volume, such crystallization leads to a gradual destruction of the joint from the surface, to plaster falling off, partial chipping of bricks, the appearance of clearly visible deposits, etc.

The phenomena of weathering are especially intensified with inevitable fluctuations in humidity, since when the humidity of the environment changes, most of the above salts either lose or re-attach crystallization water, changing the volume and causing serious internal stresses in the body of the solution. The simplest studies of clay for the content of compounds in it that can (produce efflorescence on the masonry can be done in the following way: a glass cylinder (or, better, a flask with a narrow neck) is taken and filled with distilled water; a ground brick is placed tightly on the upper opening of the cylinder or flask After that, the cylinder is turned over so that the distilled water penetrates into the brick. Subsequently, the brick is dried, and in the case of the presence of soluble salts in it, these appear in the form of a whitish coating. For the purposes of clay testing, a brick that does not have such a coating must be selected in advance. Next, the test clay is dried, crushed and mixed with a large amount of distilled water.The resulting liquid clay milk is poured into a brick, a preliminary test of which showed the absence of soluble salts in it. heels on its surface in the form of a whitish bloom. The presence of soluble salts in the clay can also be assessed by evaporating the residue from the water filtered from the clay. The presence of sediment will indicate the presence of soluble salts. Of the other impurities found in clay, in addition to the above, most may even be recognized as useful. Among (such impurities include: quartz in the form of fine particles and grains of ordinary sand, silica in the amophoric state (usually found in clay only in very small quantities), silica hydrates, mica, hydromica. The effect of mica was assessed by Professor Ponomarev, who in his research system cement-mica noted that small additions of crushed mica (in the amount of 2 - 3%) do not have a significant effect on the strength of the solution, but rather sharply increase the cohesion of the resulting mass.

More significant additions of mica significantly reduced the tensile and flexural strength of the test specimens. There is no reason to expect any harmful chemical effect of mica on the binder part of the solution, given the extremely high degree of chemical inertness of mica in general. The most dangerous effect of a significant amount of mica can be, as shown by G. Kathrein's research, a decrease in the frost resistance of the solution.

Since the content of mica in clays is very low in the vast majority of cases, there is no reason to expect a harmful effect of clay on mixed cement-clay mortars from this side. Hydrates of alumina, silica and iron oxides, sometimes present in clays in small amounts, can, according to Rodt, have a very favorable effect on the properties of the solution and, in particular, on its (strength in the long periods of hardening associated with drying.

Investigations carried out by Michaelis on gelled hydrates of calcium oxide, alumina, silica and iron oxide hydrate, dried for partial dehydration, have shown the possibility of obtaining aggregates of very high strength, especially from gels of silica and iron oxide hydrates. The influence of iron oxide, which is constantly found in clays, can also be estimated from the experiments of Grün.According to these experiments, the introduction of 30% ground iron oxide (based on the weight of cement) into cement-sand mortars 1: 3 even gives a slight increase in the tensile strength of the solutions with very insignificant changes in the compressive strength (10%). Thus, the influence of this constituent of the clay cannot be considered harmful.

The fine dust and fine sand contained in clays according to the same tests of Grün, as well as in a number of other studies, also have a rather positive than negative effect on the density and strength of cement mortars, especially during long periods of hardening. However, it should be noted that this will take place, of course, not with any amount of added additive, but only in those cases when the granulometric composition of the mortar will be within certain limits. (In addition, it should be emphasized that according to the above studies of Fere, the addition of fine sand particles incomparably increases the tensile strength of mortars and the value of adhesion than the compressive strength. This indicates that, in general, the addition of small particles can have a rather favorable effect on the quality of the mortar in the masonry, but that the assignment of the amount of tire addition should be made taking into account the resulting granulometric composition of the mortar.Hydromicas, which are always present in clays, (iron hydroxide, calcite, dolomite, glauconite, feldspars present in some clays, apparently, are harmless lean impurities.

In general, when clays are used in mixed solutions, most of these impurities have to be reckoned with as (coarse-grained impurities, partially replacing sand in mortars. With this approach, highly sandy clays should be “introduced into mortars with the obligatory consideration of the content in them coarse-grained inclusions, i.e. with a corresponding increase in the dosage of such sandy clay and with a decrease in the amount of sand introduced.

As can be seen from the above cursory list, the greatest attention when choosing clays should be paid, apparently, to the content of soluble salts and, in particular, sulphates in them. Experiments carried out at the Industrial Academy named after Comrade Stalin on the use of highly saline loess, showed that the presence of a significant amount of soluble salts in the mortar leads to the appearance of extremely highly developed efflorescences on the surface of the samples, accompanied by softening and loosening of their outer crust. In this respect, the sulfate salts of sodium, magnesium and potassium turned out to be especially unpleasant. Since soluble salts can easily have a harmful effect on mortar and masonry (the phenomenon of efflorescence - the appearance of efflorescence), clay containing a significant amount of such salts can be used only after its long aging, which promotes the leaching of sulfates or after processing it with barium compounds.

However, both methods can give an effect only in the case of a relatively low content of soluble salts in the clay and, in addition, only in relation to some of them. The danger of the direct effect of sulfates on Portland cement in a mixed solution seems to be somewhat reduced, both due to the alleged action of clay, similar to the action of weak pidravic (additives, and especially in cases of using solutions for masonry under air conditions. Since pyrite, as well as gypsum and other sulfates are undesirable impurities in clay and in the production of bricks from it, then any brick secret is usually evaluated in terms of the presence or absence of such harmful mineral impurities in it, why data from similar tests can be used when choosing clays for solutions.

Clay plaster composition and recipe

There are many compositions of clay plaster, but there is no universal recipe, the quality of the composition depends on the components. And the main one is clay for plastering walls, it is divided into 2 types: light and oily, the latter is the most suitable.

To check the quality, roll a ball of small diameter out of clay, put it on a flat surface and flatten it. If the edges remain intact, then the material is suitable for plaster, cracks have begun - the composition is of little use. Another test is to roll a flagellum with a length of 200-300 mm, with a section of 10-20 mm and gently bend it, the edges of a high-quality material do not crack.

The advantages of this type of plaster

• Depending on the proportions and additives, you can create materials that are as diverse as possible in their properties, ranging from insulating materials to those that are suitable for use in coating stoves and fireplaces;
• Clay plaster components are easy to get. And you can prepare the composition with your own hands;
• The composition of the mixture consists of natural environmentally friendly materials. However, a number of additives can be naturally radioactive;
• The material absorbs moisture well from the air, which allows you to maintain the desired humidity in the room;
• The finish thus has good sound insulating qualities;
• In the event that the plaster composition has frozen, it remains only to throw it away. However, in the case of the clay option, this is not the case, and simply adding water can return the mixture to the applicability, as well as the performance;
• High adhesion ensures adhesion to both brick or concrete and wooden walls;
• Low prices for both preparation and purchase of a ready-made composition. The only thing that needs to be considered in the latter case is information about where the clay was mined. The latter should not be carried out in ecologically polluted regions, since clay not only absorbs odors well, but also adsorbs pollution and radiation.

Material features

It would seem that clay as a building material turned out to be in the distant past in the past, but with the development of ecological construction in recent years, they began to actively use it again. The fact is that finely ground clay is a good astringent and preserving agent.

If you dilute it with water and add a filler to the solution, for example, plant fibers or sawdust, it is possible to take a good and environmentally friendly thermal insulation material. For example, such a mixture is usually used to fill hollow slag and expanded clay concrete blocks, or as an insulating plaster.

In addition, gypsum, lime or, in addition, cement is added to the mixture from time to time, which makes it possible to make the clay concrete more durable. This allows it to be used as a load-bearing material in the construction of eco-friendly houses.

The bulk density of the material depends on the ratio of ingredients. The optimal indicator is considered - 550-600 kg per cubic meter.

There is a conclusion that such material lends itself to rotting, and is fire hazardous, since it contains straw or sawdust. But this is just guesswork, since the cut of plant stems and sawdust in a clay liquid solution swell and are well enveloped with clay, which not only reliably binds them, but also preserves them.

As for the fire hazard, the filler begins to smolder only when exposed to an open fire, for example, a gas flame, for several minutes. As a result, the fire safety of the material is also higher than that of some more classic materials used in construction work.

Benefits

The growing popularity of the material is explained by its following advantages:

• Promote the formation of a human-friendly microclimate... Clay is capable of absorbing and releasing moisture more rapidly and significantly more than classic building materials. Moreover, this does not affect the strength of the material.
• Accumulates heat... Thanks to this property, the material can create comfortable conditions in housing, in addition, in conditions of huge daily temperature drops.
• Reusability, for this you need the material in water.
• Ideal for DIY home construction... The material does not require the use of construction equipment and expensive equipment. The technology of working with it is also available to inexperienced builders.
• Clay protects wood and other organic materials from decay... If you process wooden walls with it, then neither fungus nor insects will strike them.
• Clay clears the airabsorbing pollutants.
• Low material cost... That is why building with the use of clay turns out to be not only environmentally friendly, but also economical.

Cooking plaster solution

Having studied the base on which the building mixture will be applied, and the place of application (inside the house or outside), we determine the composition for plastering the walls.

Cement-sand

The most common. Suitable for indoor and outdoor work on any surface (aerated block, brick, concrete, gypsum plasterboard). The mixture is formed from cement and sand, in a ratio of 1: 3. The mixing procedure is as follows:

The stages of performing work on the preparation of cement plaster are presented: we fill in the dry leaves, mix them together and, after adding water, carefully form the mixture until ready

- we take a wide container and pour sand and cement into it;

- first mix the dry ingredients;

- gradually add water and stir until a thick homogeneous mass of the desired consistency is obtained.

The resulting solution can be of three types:

• fatty
  (excess binder). With this composition, the plaster will "crack";
• normal.
  It has an optimal ratio of components;
• skinny
  (little sand). From such a material, the coating becomes brittle and short-lived.

You can check this with a trowel. With increased fat content, the mixture sticks strongly to the instrument, drains completely - skinny, covers with a thin crust - what is needed.

Such a solution sets within an hour, so it is better to prepare it in small volumes and repeat the batch after production.

«To increase the setting time, you can add a common dish detergent to the solution.

».

Mortar

This solution has good viscosity and plasticity, suitable for all substrates, even wood. But he has one drawback. This finish is not durable and is not suitable for outdoor use (it absorbs moisture)

It consists of one part mortar and 3 parts sand. When working with lime, it must be quenched, as indicated above, and an already cooled component is used in the mixture. Sand is added to the mortar in small portions and mixed thoroughly. The filler is added until the saline solution has the desired fat content.

"When using this type of finish, remember that it sets slowly."

Cement-lime composition

Cement will add strength to the mortar. Such a coating is already used for plastering walls outside.

Prescription ratio: 3-5 parts of sand mixture and 1 part of lime mortar are added to 1 part of dry cement.

Such cement-lime plaster gains its strength only after two to three days.

Lime-gypsum mixture

The addition of stucco will help speed up the setting time of the lime composition. Improved plaster is suitable for interior decoration. It is plastic, has good viscosity, and allows you to work with a thin finishing layer.

Ready-made lime-gypsum plaster for application

To prepare, we take a clean building bucket, pour water, slowly, constantly stirring, add a plaster composition to it in a thin stream, knead everything until the dry matter is completely dissolved and the liquid thickens to a sour cream-like mass. Add lime dough. In proportion: to one share of gypsum dry matter, three parts of a previously prepared lime dough. You should get a homogeneous thick consistency.

Such a solution must be consumed quickly, because the setting time is up to 5 minutes and completely hardens in half an hour.

Adding diluted wood glue (2/5) increases the application period. For 10 liters of the finished mixture, 50-70 gr is introduced. glue.

What is it - fireclay clay

To get a clearer idea of ​​chamotte clay, it is enough to know the process of its preparation:

at the first stage, either pieces or compressed briquettes are formed from clay;

on the second, they are fired at a high temperature (from 1200 to 1500C);

on the third - the fired source material is crushed to a fine-grained or coarse-grained fraction.

Precisely because chamotte clay is fired, it is also called refractory.

Chamotte clay: composition and technical characteristics The composition of chamotte clay mainly includes highly dispersed hydroaluminosilicates such as MgO, Si02, CaO, Na20, A1203, Fe203, K20.

Obtained by firing and sintering, refractory clay has the following technical characteristics:

moisture content - no more than 5%;

the ability to absorb water - an average of 7.8% and depends on the composition of the clay;

grain size - 1.9mm on average;

fire resistance - within 1530-1830 C.

Due to this composition, processing and characteristics, chamotte clay, when mixed with water, forms a mass with good plasticity, which, when dried, has the strength of a stone.

Clay components of mortars for brick heaters

One or another type of clay oven mixture purchased in a store is prepared according to the instructions on the package, there are no questions here.

If it is decided to use a home-made mortar for laying the stove, then the main conditions on which the quality of the mixture preparation depends are two - the correct preparation of the components and the observance of the proportions of the components.

Using the example of a clay-sand mortar, we will consider the preliminary operations and mixing rules.

Using the data in this table as a basis, you can achieve high quality masonry mortar by slightly adjusting the proportions with reference to the parameters of the components used.

The natural clay prepared for the stove must be cleaned of foreign impurities - everything foreign (plant remains, stones, debris) is manually removed, and large lumps are broken. Then the mass is rubbed through a metal mesh with a mesh size of approximately 3 mm.

We suggest that you familiarize yourself with: Mortar for laying a brick oven: proportions and how to prepare

Such "dry punching" is a laborious procedure, therefore it is more rational to pre-soak the manually cleaned clay for 2-3 days in a tin trough - lay in layers of 12-15 cm, wetting them abundantly, then cover the entire bookmark with water (approximate ratio: 1 part of water per 4 parts clay). After 2 days, mix thoroughly with your feet or with a mixer and rub through a sieve with a mesh of 2-2.5 mm.

Ways to soak clay

Sand is prepared during soaking. Fireclay sand does not require preparation, except that it is sieved if purchased in bulk. And river sand must be sifted through a sieve with a mesh of 1-1.5 mm, then rinsed with running water in a container until the turbidity disappears and laid out on a clean inclined plane in order to remove moisture residues as much as possible.

There is no strict ratio of the volumes of these components, since any clay initially contains some amount of sand. Therefore, the proportion can be from 1: 2 to 1: 5, ideally the clay should only fill the voids in the solution between the grains of sand.

In order to have an approximate idea of ​​the volumetric ratio of the components, the bucket is filled 1/3 part with a clay suspension when it is ready, and then sand is poured along the edge. The materials are thoroughly mixed in any container to the desired consistency with the addition of the required amount of water. The readiness of the mixture for laying the furnace is checked as follows - it should be held on the trowel after turning its plane by 1800 and slide off it when it is in a vertical position.

Testing the readiness of clay-sand mortar

If the mixture falls from inverted to 180

base, then you need to add clay to it. If the solution does not slide off the vertical plane, add sand. After correction, the check is repeated.

By testing the solution in this way, an approximate volumetric ratio of the components is obtained.

Clay-sand mortar is used in furnace zones with temperatures up to 1000 0C. Full or partial replacement of river sand with chamotte sand allows you to use the mixture for laying a furnace with an operating temperature of up to 1800 0С, including in places of direct contact with a flame.

Variants of the classic style of stone ovens

Checking the quality of the solution

The first test is carried out before preparing the clay for the brickwork of the oven. In order for the solution to come out of high quality, it is necessary to accurately identify the fat content of the clay. It will depend on this, what additional components are required.

How greasy oven clay is revealed as follows:

1. A small amount of clay - about 1 kg - is thoroughly cleaned using one of the methods described and soaked for several days.
2. The resulting mass is divided into five identical parts. Nothing is added to the first, the second is mixed with 25 percent sifted sand, the third with 50 percent, the fourth with 75 percent and the fifth with 100 percent.
3. Each of the parts is kneaded separately. If necessary, add a little water until a pasty texture is achieved. You can determine the readiness of the solution with your hands. If it does not stick, the mixture is considered ready.
4. The resulting material is checked for ductility. Each of the five particles is rolled into a small ball and flattened into a cake. All the resulting samples are marked with labels, which indicate the proportions of sand, and sent to dry. It will take 2-3 days for the fragments to dry.
5. The resulting samples are tested. The cake should not be cracked or shattered when compressed. If you drop it on the floor, it should remain intact. Based on the results of such testing, the correct proportion of sand and clay components is revealed.

You can test for fat content and plasticity in another way. Roll into balls about 3 cm in diameter, placing each ball between two carefully rounded boards. Gently, smoothly press on the upper one, check the condition of the ball. If it cracks immediately, the composition lacks fat content. If cracks occur at half compression, the mixture is too greasy. With the correct proportion of the components, most of the specimen will flatten but not collapse.

Correctly formulated mortar does not crack immediately after application

Additionally, kiln clay is tested before use. Better to redo the mortar than waste time building a stove that will crumble. To check, the composition is scooped up by hand and rubbed with fingers. A good quality binder should be slippery and oily. Experienced stove-makers detect the readiness of the composition by ear when mixing.

Correctly made mixture "whispers" - makes a kind of rustling sound, and lags behind the shovel. You can also dip the trowel into the mixture, pull it out, and then turn it over. If a thick layer sticks, the composition is too oily, it must be diluted with sand. If the layer of solution falls off, there is an excess of sand, you need to add pure clay.

The main indicator is fat content. Distinguish between oily and skinny clay.The first, when dried, significantly decreases in volume and cracks, and the second crumbles.

Clay can be oily and skinny

Immediately, we note that there is no strictly defined ratio of sand and clay to obtain a good solution. The proportions are determined experimentally, by selection depending on the fat content of the breed.

You can determine the fat content of clay rock in the following way. Roll up the rope of clay, assuming a thickness of 10-15 mm and a length of 15-20 cm. Wrap them in a wooden form with a diameter of 50 mm. If the clay is oily, then the tourniquet is stretched gradually, without cracking. Normal provides a smooth stretch of the rope and breaks, reaching a thickness of 15–20% of the original diameter.