Brick ovens, despite several centuries of use and the development of new technologies, have not lost their popularity today, especially in rural areas. A brick oven is a complex heating structure, the internal volume of which consists of several zones exposed to high temperatures of different ranges. But even in the least heated compartments, the strength, tightness of the furnace body and chimney are very important, since the leakage of combustion products into the premises threatens the lives of residents with poisoning or fire.
The material for the manufacture of stone ovens is a brick of two types - heat-resistant and ordinary red, laid on a solution of a certain composition (depending on the heater zone). Russian, Dutch or Swedish oven - massive structures, and the consumption of materials for their construction is significant. At the same time, the cost of purchasing bricks cannot be avoided, but you can save on masonry mortar - do not buy ready-made heat-resistant mixtures, tempted by deceptive cheapness, but cook them yourself.
Ready-made dry masonry compounds for stoves and natural clay
The strength and uniformity of the brick is controlled by the manufacturer during manufacture, so it is rarely questioned. But the quality of a home-made solution - the second most important material in the construction of the furnace depends on the characteristics of the components and the correctness of manufacture.
Let us consider in more detail the furnace masonry mortars, and what kind of clay should be for laying furnaces.
Types of clay mortars for stoves and fireplaces
When laying the furnace, depending on the temperature regime of the zone being built, several types of mortar are used:
- 1200-1300 0 C - clay-chamotte and cement-chamotte;
- 1100 0 C - clay-sand mixture;
- 450-500 0 C - lime-sand;
- 220-250 0 C - cement-lime;
- atmospheric temperature range (furnace foundation) - cement-sand mixture.
Of the listed masonry mortars, clay or chamotte made from it are part of three mixtures: clay-sand, clay-chamotte and cement-chamotte).
Consider these important components of masonry oven mixes.
Clay components of mortars for brick heaters
Clay is a sedimentary rock of fine-grained structure, the forming substance of which is kaolinite, consisting of a mixture of oxides of silicon (47%), aluminum (39%) with water (14%). The name kaolin comes from the Chinese area Kaolin, where such white clay was first discovered. If there are iron ions of different valence in kaolin clay, the color of this material may be different - yellow, red, brown, blue, green, but this has little effect on the physical properties. In a dry state, clay is a lumpy material of fractions of various sizes; when mixed with water, it forms a plastic mass with good adhesion.
Clay quarry and clay sample of plastic consistency
Chamotte is a powder obtained by grinding lumps of clay that have sintered during high-temperature firing and have lost molecularly bound water in the process. The size of the fractions of fireclay chips after crushing or grinding is from 0.2 to 2.5 mm. Sifting fireclay powder allows you to separate fractions by size, after which finely ground powder is often called fireclay clay, and coarse powder is called fireclay sand, but the chemical composition and properties of these materials are identical - high heat resistance and low water absorption.
Fireclay filler industrial production and packaging
The degree of clay sintering depends on the magnitude (or) and duration of high-temperature exposure, which causes the division of fireclay into:
- low-burnt - firing temperature 600-900 0 C, water absorption up to 25%;
- high-fired - for ordinary firing at 1300 0 С and water absorption less than 5%, for special-quality - at 1500 0 С with water absorption less than 2%.
Important! Shrinkage of solutions using low-burnt chamotte is up to 16%. However, the porosity of such mortars after curing is much lower than that of mixtures with high-burnt filler, since the difference in shrinkage of low-burnt chamotte and binder (clay) is very small. Therefore, to obtain heat-resistant bricks of low porosity, high compressive strength and fracture, low-burnt chamotte is used, and for masonry mortars, high-burnt one.
Characteristics of clay for kiln mixtures
The main characterizing parameter of this material is fat content, which combines the degree of plasticity, strength, water resistance, as well as adhesion before and after curing.
In nature, there are three types of clay - skinny, medium fat and oily, with no clear boundaries between them.
The belonging of the material to one of the types is determined by simple mechanical manipulations, the most accurate of which is performed as follows.
Approximately half a kilogram of clay is kneaded with water until a homogeneous pasty consistency, after which a ball with a diameter of approximately 5 cm is formed from the resulting mass.
The ball is placed between two pieces of glass, with which it is slowly squeezed, observing the formation of cracks in the clay:
- the destruction of the ball at the beginning of squeezing indicates a low fat content - the clay is lean;
- the appearance of thin cracks after reducing the diameter of the sample by 1/3 of the original value indicates that the clay is of normal fat content;
- if cracks appeared only when the ball was squeezed to half the diameter - a mass of high fat content.
Determination of the fat content of clay by squeezing: on the left - oily, on the right - normal.
The main factor affecting the fat content of clay is the weight percentage of sand in it:
- from 15 to 30% - skinny;
- from 5 to 15% - medium fat;
- up to 5% - fatty.
Production of clay masonry mortars
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 furnace, then there are two main conditions on which the quality of the preparation of the mixture depends - the correct preparation of the components and the observance of the proportions of the components.
On the example of a clay-sand mortar, consider the preliminary operations and mixing rules.
Using the data of 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 furnace must be cleaned of impurities - everything extraneous (plant remains, stones, debris) is manually removed, and large lumps are broken. Then the mass is rubbed through a metal mesh with a cell format of approximately 3 mm.
Such a “dry punching” is a time-consuming procedure, therefore it is more rational to pre-soak 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 to 4 parts clay). After 2 days, mix thoroughly with your feet or with a stirrer and rub through a sieve with a cell of 2-2.5 mm.
Ways to soak clay
During soaking, sand is prepared. Fireclay sand does not require preparation, except to sift, if purchased in bulk. And river sand must be sifted through a sieve with a mesh size 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 to remove moisture as much as possible.
There is no strict ratio of the volumes of these components, since sand is initially present in some amount in any clay. Therefore, the proportion can be from 1:2 to 1:5, ideally clay should only fill the voids in the solution between the grains of sand.
In order to have an approximate idea of the volume ratio of the components, the bucket is filled with 1/3 of the clay suspension when it is ready, and then the sand is added 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 must be held on the trowel after turning its plane over 180 0 and slide off it in a vertical position.
Testing the readiness of the clay-sand mortar
If the mixture falls from a base inverted by 180 0, then clay must be added to it. If the solution does not slide off the vertical plane, add sand. After correction, the test is repeated.
By testing the solution in this way, an approximate volume ratio of the components is obtained.
Clay-sand mortar is used in furnace zones with temperatures up to 1000 0 С. Complete or partial replacement of river sand with fireclay allows the mixture to be used for laying a furnace with an operating temperature of up to 1800 0 С, including in places of direct contact with the flame.
Important! Clay mortars without the use of cement make it possible to disassemble the brick heater after curing and reassemble it without destroying the elements.
Variants of the classic style of stone ovens
A more visual answer to the question of how to prepare a mortar for laying a furnace is given in this video:
Conclusion
The availability of clay in natural conditions does not mean its primitiveness as a building material - solutions based on this mineral, prepared correctly, have served in stone heaters for centuries. Therefore, the use of clay-based mixtures is a sign of the professionalism of the stove-maker, and not a reason for skepticism.
The main essence of the article
- A stone oven is a complex engineering structure, the effective use of which depends, among other things, on the quality of the materials used for its construction.
- Clay is an affordable natural material, and today it has not lost its demand, but surpasses Portland cement in a number of characteristics.
- For high-quality masonry, it is necessary not only to choose the right clay for the stove being built, but also to prepare it in a quality manner for incorporation into the solution.
- The high quality of the components of the mortar for laying the stove guarantees the functionality of the mixture only if the required proportions are observed.
- The advantage of clay, among others, is the ability to completely sort out the masonry again without damage to the dismantled materials.
Clay is the best material for preparing mortar for masonry. It is economical and highly durable. But it is important to responsibly approach the choice of raw materials and familiarize yourself with all the nuances of preparing the solution.
How to choose the right clay
The main characteristic of clay is its fat content. This concept includes a number of qualities:
- Plastic.
- Strength.
- Water resistance.
- The ability to good adhesion (adhesion).
- Gas density.
Clay does not have to be purchased at the store. It occurs in abundance in the deep layers of the soil. In order not to have to dig a deep hole in search of good material, it is worth walking along the steep bank of the river - there you can see earthen layers up to clay, choose the right one. It is important to remember: the higher the layer, the fatter the soil. Therefore, it is worth taking samples from several layers, and after checking, choose the best one.
But even inappropriate material can be corrected. Too fatty raw materials are diluted with sand, and the skinny is combined with a small amount of a purchased quality mixture.
Checking the quality of clay
The quality of raw materials can be determined tactilely, right in the field. You need to mix a small amount of clay with water. If the mass is dense, viscous, then the material is good. If the mixture crumbles, you can’t do without fat..
Determine the fat content
There are several more accurate ways to analyze the characteristics of raw materials.
It is necessary to prepare a batch of half a liter of raw materials and 150 ml of water. The "dough" should be kneaded until it stops sticking to the hands. Then roll the mass into two balls, dry them for several days. If after drying they cracked - the clay is too oily, it needs to be diluted. And if the balls are smooth, do not break on impact - the solution is ideal for oven masonry.
Read also: Repair of brick ovens
Mash 2-3 liters of raw materials in a special container with a paddle. After thorough mixing, you can proceed to the test. A mass that is suitable in texture will hang on the instrument in the form of separate clots. But if the whole thing sticks, the material is too greasy.
Dilute half a liter of clay with water until smooth. Roll into a ball with a diameter of about 5 centimeters. Then put it between two planks, then flatten it. Quality is determined by the nature of the cracks:
- If the ball crumbles at the slightest pressure, the clay is thin.
- If cracks appear only when compressed by one third, the material is of excellent quality.
- Too fatty raw materials will crack slightly only after squeezing the ball by 50%.
We clean from impurities
Once the required material has been selected, it must be undergo a cleaning process. In this way, you can achieve an improvement in all quality characteristics. There are several cleaning methods:
- You can sift dry clay through a sieve with cells of 2-2.5 millimeters. This is a rather long tedious way, since the mass quickly clogs the holes.
- It is much faster to wipe the mixture diluted in water through a mesh with larger cells.
The second way is more convenient, especially since soaking is still indispensable. This procedure is performed before or after cleaning, depending on the method chosen.
Finally, the ingredients should be prepared as follows: the required amount of material must be distributed over a special container with a layer of 15-20 centimeters and completely filled with water. Above - another layer of the same thickness. Repeat the process until the container is full. You need to mix the mass once a day, adding water if necessary. This completes the preparation. After 2-3 days you can start working.
In a brick kiln, there are zones with varying degrees of temperature and chemical load, and it is correct to use different solutions with different characteristics in them. For example, it is better to put the firebox on a solution with the addition of chamotte sand - clay-chamotte or cement-chamotte. They withstand from 1100°C to 1200°C, at high temperatures they are sintered together with bricks, forming a monolith. The rest of the oven can be laid on a clay-sand mortar. Its characteristics are optimal for this (withstands temperatures up to +450°C, has a high density, does not conduct gases). Some parts require more strength (chimney and furnace base), when laying them, some cement or lime can be added to the mortar. So the mortar for laying the furnace will not be one, but at least three.
Almost any solution is made on the basis of clay. For the body of the furnace, a certain amount of sand is added to it. Moreover, it is possible to say exactly how much exactly only by “feeling” the source material (in the literal sense) and making a certain number of test batches with different amounts. Based on the test results, the best ratio is determined. Only this way, and nothing else. This is the only way to make the right solution on which the oven will stand for a long time.
Where to dial
To save money, you can collect clay from your site. This is permitted by law (from a depth of up to 5 meters). You just have to dig about 2-3 meters to get to deposits with more or less acceptable characteristics. The second option is to collect clay in the nearest ravine, on a steep river bank, etc. This is no longer permitted by law, but is practiced everywhere. And the third option is to buy clay in a store or from stove-makers, but it will be necessary to determine its qualities and prepare it in the same way as it was obtained independently.
So, we go to the ravine, to the river bank or dig in the pit garden. If you look at the structure of a clay pit in a section, you will see a number of layers. The upper one is usually fertile, with a large amount of organic matter and plant residues. Even if its main component is clay, it definitely does not suit us. The required layers lie below. Maybe under a layer of sedimentary rocks, maybe under loam (clay with a very high content of sand). We go down much lower - deeper than the lower edge of the fertile layer by 1.5-2 meters. The color of the desired clay can be any - from whitish and gray to red. It is not important, characteristics are important.
The fat content of clay layers increases from top to bottom. Ideally, material should be taken from the middle layers. Here are, as a rule, clays of medium fat content, namely they are optimal for the main solution. For fireclay, it will be necessary to take a certain amount of very light and oily clay from the lowest layers.
Determination of fat content on the spot
Fat content is determined on the spot. We take a piece of clay from any layer (less than a fist in size). We moisten the hand, pinch the lump, try to knead it. We are waiting for the water to be absorbed. Repeat until the clay becomes plastic. We roll the ball, we begin to compress it from above and below with two smooth, even plates (pieces of wood, metal, etc.). In the process, cracks begin to appear. If they began to appear only after the lump was compressed by 1/3, then the solution is either normal or oily and this layer can be used. If earlier - the clay is skinny, and it is better to try another, because sand grinding is a long and very dreary business, it requires a lot of water.
From the selected layer (or layers) it will be necessary to take about 5-6 kilograms of clay. They are needed to determine the amount of sand in the mortar for laying the furnace. The main thing is not to forget which clay is from which place and not to confuse.
Sand and water
Sand can, of course, be bought. It is usually sold divided into fractions. You will need at least two - 0.7-0.9 mm and 0.15-0.25 mm. They are required in a ratio of 1:2.
To save money, sand can also be found in the same places where there are clay deposits. If you are lucky enough to find white - quartz, it can be used for any mortar, and yellow - crushed feldspar, not suitable for laying a firebox, but it will do for other parts.
The best clay for laying the stove is white or kaolin. Sand can also be found between the layers of clay
Water needs soft or completely demineralized, purified. You can collect and defend rainwater ahead of time, you can buy / collect purified water. It is important that it be soft or medium hardness (hardness no more than 10 points). A large amount of salts greatly degrades the quality of the solution.
Sand preparation
If the sand was mined by yourself, it must first be sieved through a sieve with a fine mesh (1-1.5 mm). This separates large impurities and debris. Screened sand contains a lot of living creatures and alumina impurities, which can significantly degrade the quality of the solution. You can get rid of them by washing. To do this, make a special device.
Take a pipe with a diameter of 150-200 mm. Its length is three times the diameter (450-600 mm). A drain is formed in the upper part, water is supplied from below. The container is filled with sand by 1/3, the water pressure is made such that the sand swirls in the upper part, but does not merge. Rinse until clean water begins to drain, waiting another 5-10 minutes to be sure.
The washed sand is laid out on oilcloth, tarpaulin or other dense material, in some kind of container. You can dry it, you can use it wet, but when kneading it is necessary to take into account its humidity.
We determine the proportions
It is necessary to work with the selected clay samples - select the amount of sand, check them, reject the worst ones, leave the best ones. Too many samples can confuse you. If the tests "on koloboks" gave different results, leave the one in which the cracks appeared after it was compressed by a third. In this case, it is highly likely that you have found deposits in which you will not need to add anything. It will only be necessary to dilute with water to the desired consistency. The time savings are huge.
If you can’t decide exactly, leave two, maximum, three samples. This will be a large number of batches and a lot of tests.
How much sand is needed in the mortar for laying the furnace
Since we brought normal or oily clay from the quarry (if everything was done correctly), we need to determine how much sand needs to be added to it. This can only be done by experience. The procedure is as follows:
We leave everything to dry not in a draft, without access to sunlight. After 2 days, we wrap one tourniquet from each batch around the shovel handle and look at the number and depth of the cracks that have appeared. In a normal composition, the dried crust and a slightly inner, still wet part should crack. The skinny one has a lot of cracks and they are very deep, while the fat one has mostly superficial ones. So we choose compositions with normal fat content.
How to determine the appropriate composition of the clay solution
To confirm our assumptions, we test the second clay sausages. We pull them by the ends to the sides, tearing. For a normal composition at the point of rupture, the thickness should be approximately 1/5 of the original (if the thickness was 15 mm, then the diameter at the rupture will be 3 mm).
These tests usually yield two or three suitable formulations. Having rejected those that do not fit, koloboks and cakes are left to dry. This takes up to 20 days. Then we drop them from a meter height, we look at which of the compositions turned out to be the most durable - it will be the best.
For a long time? Yes. But this is the only way to find the most durable mortar for laying the furnace. If there is absolutely no time, these tests can be skipped. But it will be necessary to check whether the fat content of the solution is chosen correctly. Do this after dilution with water (described in the paragraph "Quality Control").
How much water
In the furnace business, it is important that the mortar for laying the furnace also has an optimal viscosity, which depends on the amount of water. We make a test batch from the half that was postponed. We soak it, wipe it through a sieve, add sand according to the proportion found. If it doesn't mix well, add a little water.
Clay is mixed with a board or a “veselka” - a board planed in the form of a small oar. After we have achieved uniformity, we carry out a simple test.
We take a trowel, and draw an edge along the surface of the solution. If the trace remains “torn”, add a little water, stirring thoroughly. If the edges of the left furrow swim up, a lot of water has been poured. We must wait until the water settles and stands out on the surface. Then it can be collected. The second way is to knead some more obviously “dry” solution, and mix everything. With a normal consistency, the clay mortar under the trowel has a flat surface, the edges of the grooves keep their shape.
Quality control and storage
After you have kneaded a trial batch of clay mortar for laying the furnace, we test it again:
- We take a trowel, collect a little solution on it and turn it 180 °. A normal solution in this position hangs quietly, a lean solution (a lot of sand) falls.
- Turn the trowel with the solution 90 ° (edge down). A normal solution slowly slides down, falls, leaving a thin, almost transparent film of clay on the metal. If the solution is greasy, it almost does not slip, or leaves a thick layer on the metal.
- We take two bricks. On one we apply a layer of mortar of 2-3 mm, put the second one and tap it with a trowel, as when laying. We leave for 7-10 minutes. we take the upper brick and raise it. If the second brick hangs, does not fall even with active shaking, then the solution has been made good.
If all tests have passed normally, according to the proportions found, a large amount of clay mortar can be kneaded. The finished clay solution can be packed in buckets or poured into barrels, closed with a lid. In this form, without changing the quality characteristics, it can be stored for months.
Features of the preparation of solutions for other parts of the furnace
As already mentioned, for laying a good bath brick oven, in addition to clay, two more mortars will be required: with fireclay for the firebox and with cement or lime. for pipe and base.
How to prepare a solution with fireclay
To prepare a mortar for laying the firebox of a sauna stove, you need to choose clay from the lowest layers - very oily. It is usually almost white, light gray or slightly yellowish. Fireclay sand or mortar is added to the soaked and rubbed clay (must be bought at the store). Sand will take a lot, but it costs a lot. To save money, it can be mixed with quartz (white) in a ratio of 1: 1.
Since the clay is obviously oily, test batches are made by adding a large amount of sand at once - from 3/4 and more. When mixing this solution, high requirements are placed on the quality of water - it must have a hardness of no higher than 8 points. When compiling a fireclay solution, it is only necessary to determine the required amount of sand. Tests for strength are unnecessary - fireclay is a guarantor of the required qualities.
Is it possible to use a ready-made mortar for laying fireboxes with fireclay? It is possible, but it costs a lot of money, and it will take quite a lot of it.
Lime or cement-lime mortar
The base of the furnace and the fluffing of the chimney is made from a mortar with increased mechanical strength - with the addition of lime and / or cement.
To prepare a solution using lime, lime dough is needed. Not self-slaked fluff, but a pasty mass made by professionals. This is the material on which it is better not to save. It is advisable to buy it ready-made, packaged in sealed containers (see expiration date). With self-extinguishing of fluff, particles of quicklime remain in the paste. During operation, they absorb water vapor, extinguish, and tear the seams. Therefore, it is more expedient to use ready-made lime dough, and of good quality.
Lime dough does not have to be bought in buckets, you can - in bags
For the preparation of lime mortar, self-extracted sand, sifted through a sieve with a cell of 1 mm, is suitable. It is not necessary to rinse it, since lime will destroy all microscopic living creatures, alumina impurities will not affect the strength of the solution either. If the sand is purchased, then its fraction is 0.7-0.9 mm. Any drinking water can be used, including tap water. There are no requirements for hardness, but technical water with impurities still cannot be used.
Preparation of lime mortar for the kiln
Open the container, knead the dough with a smoothly planed wooden paddle. Start adding sand in portions, achieving its uniform distribution throughout the mass. The “starting” amount of sand is 1/2 of the volume of lime. After mixing everything, look at the fun. A solution is considered normal if the solution layer on the surface is 2-3 mm, with possible small tubercles and streaks. If a very thin, almost transparent layer remains on the plane, through which even wood can be seen, the mortar is thin (too much sand). If the layer is large and loose, there is little sand, the solution is too greasy.
Lime mortar can be kneaded with a drill, but it is necessary to test the fat content with the help of planed wood. So fat content is determined most accurately.
When determining the proportions of lime mortar, we take more sand, but the plasticity rate remains. Specialists first bring the solution to a slight “fatty” by adding up to 5 parts of sand to 1 part of the dough, and then bring it to the norm by adding pure paste. In this case, the strength of the seam is provided precisely by grains of sand, and lime only sticks them together.
Viscosity (amount of water) is checked with two bricks. On one we lay a solution of about 3-4 mm, on top - the second brick, tapping lightly with a trowel handle, level it. On the sides, a bead of mortar with a thickness of about 1-2 mm should form. If it stands and does not drain, everything is fine. Close the solution properly. If there is no roller, the solution is not squeezed out, you need to add a little water. If, on the contrary, the roller floats down, there is too much water, add paste (sand, as agreed, was placed at the maximum limit within the limits of plasticity, so a small amount of paste will not hurt).
Cement-lime mortar
The proportion of cement in this solution is very small. At least 9 parts of lime paste (and no more than 15) are taken for one part of cement. Brand of cement - from M200 to M600. The higher it is, the less this component is required, but the strength of the mortar increases when high-quality cement is used. It is possible to use ready-made adhesive composition for furnaces as an additive. Its main component is high-quality cement.
The difficulty lies in the fact that this solution has a short shelf life - it must be used within 45 minutes from the start of the batch. Therefore, it is necessary to conduct experiments with the amount of sand and water on a trial batch (all actions are similar to the determination of the lime composition). When mixing the working cement-lime mortar for laying the furnace, all pre-measured components are mixed quickly, in a certain order. The finished material is immediately taken to work.
You can mix the solution with the same veil, or you can use a drill with a nozzle. The kneading order is:
- First, water is added to the lime (if it is necessary according to the test results), stirred until smooth. Stir with a mixer for about 2-3 minutes, by hand - 10-15 minutes.
- Continuing to stir, add the required proportion of cement in a thin stream. Having achieved the homogeneity of the composition, mix several more times.
- Continuing to interfere, gradually add sand. After pouring out the entire required volume, mix a couple more times. The solution is ready for use.
All these subtleties have been developed empirically. The technology is different from the one used by our ancestors. They beat clay. For laying a simple cooking stove, just broken clay is also suitable, but for a sauna stove with its temperature conditions, a good, strong mortar is required.
Clay mortar, ideal for laying bricks, it is important to be able to cook correctly. The quality of the binder ingredients, the purity of the filler, and the hardness of the water matter here. A good mixture is actually not difficult to make on your own, if you strictly follow the proportions and follow the preparation procedure described below.
About solution
The clay-based composition is mainly used for the construction of stoves in a private house. Its properties allow the masonry to provide strength and durability.
In the bath, the base (and even more so the chimney) on this masonry mixture is unacceptable to build. Here it is much better to use the solution:
- lime;
- cement-sand.
Neither one nor the other is afraid of condensate, which usually forms on these elements of the furnace.
The main characteristic that you need to pay attention to when making a clay composition is fat content.
It depends on it as a result:
- plastic;
- degree of final shrinkage;
- resistance to high temperature;
- the strength of the entire masonry.
In total, experts distinguish three types of solution:
- skinny is very fragile and has low plasticity - it often cracks when dried;
- fatty - malleable, but after hardening it may begin to crumble;
- normal - ideal for masonry.
The latter variety has the following properties:
- does not give significant shrinkage;
- withstands strong heat;
- have excellent plasticity.
It is a pleasure to work with him. Using a normal solution, the oven can be easily folded even by a not very experienced master.
How to find out how plastic clay is
In principle, the test is not difficult at all. To do this, take a bucket of cool water and gradually begin to add clay to it. The main task is to get a consistency similar to that of ordinary store-bought sour cream.
Mix the solution not with a trowel, but with any suitable plank. When the result is achieved, it is pulled out of the bucket and inspected. If enough clay has stuck to it, then it means that it is quite oily and equally plastic.
- pour the entire volume at once;
- mix thoroughly;
- check on the plank (the norm is 2 millimeters of the mixture on its surface);
- add more aggregate as needed.
Making a solution
The preparation of a high-quality clay mixture in individual steps is as follows:
- a day before the start of work, the clay is soaked in a small amount of water;
- 24 hours later, they begin to mix it with a shovel, gradually adding water;
- when the mixture becomes like sour cream, filter it;
- then they begin to add sand in the proportion indicated above (a liter per bucket).
The fact that the process is completed is indicated by the absence of puddles on the surface of the solution. Otherwise, keep adding a little bit of the placeholder.
Another variant
This method is only suitable if you have absolutely clean clay, in which there are no foreign inclusions and pebbles. Here the procedure begins with the addition of the sieved aggregate. Then add water to a quarter of the total volume.
The composition is mixed until smooth (it is permissible to use a concrete mixer) - as a result, it should fall freely from the shovel blade, but not spread.
The last step is the addition of dry cement (750 grams per 10 liters) and salt (about 200 g).
Other options
In this case, you will need to stock up on fireclay sand and refractory clay. Both ingredients are mixed in equal proportions. After that, water is poured in an amount of 1/8 of the total volume of the solution. When the mass becomes homogeneous, it can be used for its intended purpose.
It is permissible to make a composition from loams. In this case, you will need to prepare 10 different options for testing in a small amount. The first one takes:
- 10 parts loam;
- 1 - cement;
- 1 - sand.
The finished sample is thoroughly kneaded until smooth, adding clean water little by little. It is necessary that no lumps remain as a result.
The finished samples are placed in separate boxes and left for a week. When time passes, they are examined. The composition is suitable for the oven:
- containing a maximum of clay;
- not cracked.
It will quite calmly withstand heating up to 600 degrees, without deforming or crumbling.
Specificity of lime and cement mixture
As previously noted, chimneys and the foundation of the stove are constructed using other quick-drying and stronger solutions.
The universal composition is prepared as follows:
- the sand is sifted;
- mixed with cements of the 400th brand in a ratio of 3 to 1;
- add water immediately before starting work.
The desire to build a real heating brick structure in the house on their own, quite common among the owners of suburban housing, naturally gives rise to a large number of questions about the work. One of them is about what kind of mortar is needed for laying the furnace.
Indeed, a lot depends on the composition of the mortar: how well the masonry will be done, what will be the durability and safety of the operation of the stove itself, whether the finished structure can become an interior decoration. Therefore, before proceeding to the choice of masonry composition, you need to familiarize yourself with information about some of the nuances of its use.
The main nuances taken into account when preparing a masonry mortar
- For the high-quality construction of the furnace, it is necessary to prepare not one, but several solutions, taking into account the area of \u200b\u200btheir application.
- The solution for the furnace must be made with skill. It will not work to mix a clay-sand or cement mortar, if only as - it will not work, since it is necessary to take into account the conditions in which it will be operated:
- temperature and mechanical loads that the furnace will experience, as well as the influence of external atmospheric factors on the open section of the chimney pipe;
- temperature difference in different zones of the furnace structure. So, in the furnace, the temperature rises to 950 ÷ 1000 ° C, at the mouth of the chimney - up to 50 ° C, and around the foundation, in the surrounding soil, there is only about zero.
Of course, the easiest way would be to purchase a dry composition at a hardware store and make a solution from it. However, it should be borne in mind that for laying 100 standard-sized bricks laid flat, about 20 liters of the composition will be required - this is approximately two buckets. Depending on the model of the chosen furnace, its construction will require from 500 to 2000 bricks, excluding the chimney and foundation arrangement. Therefore, looking at the prices in stores and calculating the required amount of materials, many people think about making solutions on their own.
Based on this, it is worth answering some traditionally arising questions regarding the masonry mixture:
- Where can you independently obtain the most important component of the mortar for laying the furnace - clay, thereby saving a round sum on its purchase?
- How to determine the quality of the material and its suitability for the manufacture of furnace mortar?
- How to choose the right proportions of the mixture, based on the quality of the material that is available?
- How is the preparation of the components of the solution?
- How to carry out the kneading?
- What ingredients besides clay can be used for masonry?
First you need to figure out what solutions are used for masonry in different zones of the furnace structure.
Mortars for laying various sections of the furnace
What composition of the mortar should be chosen so that the masonry is reliable and its seams do not crack?
This scheme divides the structure of the furnace into numbered separate departments, which are worth going through, determining the solution for each of them:
1 - Monolithic foundation of the furnace. It is made of reinforced cement-sand mortar and has the same depth as the foundation of the walls of the house. A very important condition when choosing a place to install the furnace is its remoteness from the bearing walls. The foundation of the heating structure and the building should not be connected, and even more so - be united with each other, since they shrink differently.
2 - Waterproofing is laid on a frozen and hardened foundation. Usually, roofing material is chosen for this, which is laid in two or three layers. Laying this material does not require any mortar.
3 - The first two rows of masonry are usually the basis for the entire structure, therefore they require special accuracy and accuracy when laying them. The reliability of the laying of the rest of the furnace depends on how well they are brought out. The foundation and the lower rows of the building do not experience serious temperature loads, therefore, cement-lime or even lime mortar can be used to lay this part of the furnace.
5 - In the heat storage area of the furnace structure, the heating of bricks and mortar reaches 550 ÷ 600 degrees. In addition, this zone of the structure is exposed to aggressive effects of hot combustion products, therefore, a clay-sand mortar is used for laying bricks, which does not react with chemicals.
6 - The furnace zone of the furnace experiences high temperatures, reaching up to 1000 degrees, therefore, clay-fireclay refractory mortar and fireclay bricks are used for this area.
7 - The source of the chimney. For the laying of this structural element, a clay-sand mortar is used. The temperature in this zone can reach up to 350÷400 degrees.
8 - The fluffing (cutting) of the chimney pipe is located under the ceiling of the room, in front of its passage through the attic floor. Since gases heated to high temperatures pass through the pipe in this section, its laying is also carried out on a clay-sand mortar.
9 - The passage of the pipe through the attic floor, which is very often made of combustible materials. Therefore, a metal box is installed around the pipe in this place, which is filled with non-combustible material, such as expanded clay or sand. Brickwork is made on a clay-sand mortar with a small addition of cement.
10 - The neck of the chimney. This zone experiences high loads from temperature extremes, as well as external weather factors, therefore, a cement-sand mortar with a small addition of lime is used for its masonry.
11 - The head of the pipe, as well as its neck, is laid out on a cement-sand mortar.
Solutions made independently and used in combination will help save up to 12÷15% of the cost of purchasing ready-made heat-resistant mixtures.
Raw Materials for Furnace Solution
A few words must be said about the materials that are used for the manufacture of masonry mortars for furnaces, since they must also be chosen with skill. These materials include fireclay and quartz sand, clay, lime and cement.
Chamotte is a refractory clay that has undergone a high-temperature firing process, in which moisture was completely removed from it, and the material was brought to a state of sintering.
Fireclay sand is made from fireclay bricks crushed by crushing. This material makes the solution more resistant to high temperatures, so it is often used instead of sand or as an additive to the mixture intended for the combustion chamber, which, accordingly, is laid out with heat-resistant fireclay bricks.
Fireclay sand does not require too much, so you should not save on it. It can be purchased ready-made in specialized stores.
Clay
Clay is a microgranular mineral with a number of advantages such as plasticity, strength, water resistance, high adhesion, and gas tightness. All these properties can be reduced to one quality - fat content, since it is on this basis that the material is selected. For the manufacture of oven masonry mortar, clay with an average fat content is ideal. If the mineral is too greasy, then when moisture evaporates from it, the surface will crack into a fine mesh. Well, when using lean clay, the solution will not have the proper plasticity and reliability.
Clay can be easily found in the vicinity of a suburban area, as it, as a rule, has a wide distribution in any area. Good material usually lies at a fairly large depth, so it is better to look for it on steep river banks or in quarrying, where you can see its many exposed layers.
Selection of clay by fat content
Clay with different compositions lies in the layers, therefore, in one quarry or on a cliff, a mineral with different fat content can be found. In this regard, when selecting material for the manufacture of masonry mortar, it is necessary to take samples from several layers, while focusing on the fact that the higher the layer is, the fatter the clay in it.
However, if too oily or lean clay was found or purchased, then its composition can be adjusted. For example, a fatty mineral can be brought to the desired state by adding a little more sand, and a lean mineral is mixed with a fatter clay purchased in a small amount specifically for this purpose.
The fat content of clay can be determined immediately at the place where it is found. For this, a handful of dry mineral is taken, wetted with water and kneaded to a plastic state. You can already feel in your hand how high the fat content of the raw material is - so if the clay takes on the consistency of plasticine, then this means that the material is oily. If, after wetting and kneading, the lump continues to crumble, then the clay is skinny, and it will have to be greased.
You can test the quality of the clay at home, and these results will be more reliable than the conclusions after the usual compression of a lump of mineral in your hand. There are several ways to control this:
- 0.5 l of clay is taken, to which 100 ÷ 150 ml of water is added. Then the whole mass is thoroughly kneaded with hands until smooth - it should not stick to the palms. Two balls with a diameter of 45 ÷ 50 mm are rolled from the resulting “dough”, and one of them is crushed into a cake. Then they are dried at room conditions for two to three days.
If after this time cracks appear on the experimental samples, then the clay is too oily and a little more sand should be added to it than indicated in the recipe for making the solution.
If no cracks are found, and a ball thrown to the floor from a height of one meter does not break into pieces, then the clay is suitable for masonry stove mortar.
- The second way to check is to knead 2 ÷ 3 liters of clay with water using a paddle. If the mass sticks to the tool with almost its entire volume, then the clay is oily and requires an additional portion of sand, more than indicated in the recipe.
Clay is considered suitable for masonry mortar, which, when mixed, remains on the paddle in separate clots.
- The third method of verification can be called the most accurate. It consists in kneading 0.5 l of clay with water to a dough state. Further, a ball with a size of 45 ÷ 50 mm rolls from this mass. Then it is placed between two smooth boards and gently squeezed until cracks begin to form on it, which has turned into a cake.
When using this method of verification, the fat content of the raw material is determined by observations, upon reaching what thickness cracks formed on the cake, and what form they take.
- So, if the clay is thin, then even with a slight compression, the ball will crumble into separate parts.
- If a clay ball cracks when compressed by ⅓ of its diameter, then the clay has a normal fat content and is perfect for making furnace mortar.
- Very oily clay, when compressed to ½ of the original diameter, forms only thin cracks.
By conducting such tests, you can immediately bring the experimental mass to the desired state by adding sand or more oily clay to it. It is recommended to write down the proportions of the best options. When the optimal ratio of materials is determined, it will be much easier to make up any amount of mortar.
Clay cleaning
After the clay is selected, it must be cleaned, since after this process the physical and mechanical properties of the raw materials will improve, which means that the masonry itself will be of better quality both in terms of technical and aesthetic characteristics. The cleaning process can be carried out in two ways:
- Dry clay is crushed and sieved through a sieve with cells no more than 2 ÷ 2.5 mm. However, such cleaning is not very convenient, since the clay is not as free-flowing as sand, and will quickly clog the cells.
- Better cleaning will be obtained if the clay is first soaked, and already in a swollen state, wipe through a sieve, on which a mesh with cells of 2.5 ÷ 3 mm is stretched.
The process of soaking clay can also be attributed to the preparatory work, and in any case, you can’t do without it. If cleaning is dry, then soaking occurs after completion of this operation. In the same case, when the clay is cleaned by rubbing, soaking occurs before cleaning, and as necessary, a little water is added to the wet rubbed clay.
When soaking dry sifted clay, it is poured into a container with a layer of 150 ÷ 200 mm thick and then filled with water, which should completely cover the surface of the material.
The next layer of the same thickness is laid out on top, and also filled with water, then clay and water again, and so on, until the container is filled almost to the top. The soaked clay is left to swell for a day, and then the entire contents of the container are mixed with a shovel. Further, water is additionally added to this mass, and the soaking process is extended for another 24 hours. After that, the clay should be thoroughly mixed again, and now it will be ready for the preparation of the masonry mortar.
Sand
On the steep banks, between the layers of clay, one can also find a layer of sand suitable for the furnace solution. For example, white quartz sand is perfect for laying any area of the furnace, and yellowish sand will be unsuitable for the combustion chamber. If the sand is mined independently, then you need to know that it requires some preparation using a large amount of water. If this material is purchased, then you need to buy washed river sand. But even in this case, the material will have to work.
Sand washing is mandatory, especially in cases where it was mined independently. The process is carried out in the following sequence:
- The first step is to sift the sand through a metal sieve with cells no more than 1 ÷ 1.5 mm. Thus, a homogeneous mass is obtained, purified from large fractions and plant debris. Nevertheless, even sifted, but untreated and unwashed sand is saturated with organic matter, from which it must be freed, since over time it can lead to the destruction of the masonry.
On an industrial scale, sand is cleaned of organic matter by heating it to high temperatures, at which it dries well. At home, the sand can be cleaned by washing, but this cleaning option will be possible if the water supply is connected to the house, since a lot of water is required, and it must be supplied under sufficient pressure. The productivity of such cleaning is low, but in a couple of days it is quite possible to wash sand for laying one furnace.
- To carry out the washing operation, it will be necessary to make a special simple device consisting of a galvanized pipe with a diameter of 200 ÷ 250 mm, a height of 600 ÷ 750 mm. A large container is not suitable, since there is simply not enough pressure for the sand laid in it in the water supply system. The lower part of the pipe is made cone-shaped with a special spout for attaching a water hose to it, the second end of which is connected to the water supply system. A drain is made at the top of the pipe, through which dirty water will leave.
- The container is suspended and filled with sand to ⅓ of its volume. Then the water is turned on under a slight pressure, with the same calculation so that it can lift the washed sand. The sandy mass should, as it were, swirl, but not go down the drain with dirty water.
Rinsing of each portion is carried out for approximately 7 ÷ 10 minutes, until clear water begins to flow into the drain.
During such washing, not only organic matter is removed from the sand, but also other impurities that are undesirable for the furnace solution.
Then, clean sand is removed from the washing tank and laid out on the spread material for drying, and the next portion is laid for processing.
Cement
Cement is an inorganic binder that, when mixed with water, forms a plastic mass. When solidified, the mixture using cement becomes hard, but rather brittle. Therefore, to acquire greater strength, cement is mixed with sand, and sometimes, to increase plasticity, lime is added to it.
Cement has a digital marking, which indicates the compressive strength of a prototype cement pour, it can vary from 200 to 600 kg / cm². For kiln masonry and foundation construction, cement grade M400 is suitable.
The composition of cement usually includes additional ingredients - finely ground gypsum and clinker, which is obtained from the raw mass of clay and limestone, by firing before sintering. These components give cement the qualities necessary for masonry work - high adhesion, plasticity, strength, etc.
Prices for cement M400
cement M400
Lime
Lime is a white mineral substance obtained by burning limestone. Its chemical composition is calcium oxide.
Hydrated lime is used for additives in mortars, which makes them more plastic and allows them to solidify evenly.
Characteristics of solutions and their manufacture
In addition to knowing the characteristics of individual constituent materials, it is necessary to have information about the effect obtained when they are mixed, that is, about the characteristics of ready-made solutions, as well as about the technology for their preparation.
Table of consumables for the manufacture of the most commonly used solutions for laying furnaces:
Name of materials | clay mortar | Mortar | cement mortar |
---|---|---|---|
Material consumption in parts | |||
Sand | 4 | 2.5 | 3 ÷4 |
Chamotte clay | 1 | - | - |
regular clay | 1 | - | - |
Lime | - | 1 | - |
Cement M400 | - | 0.5 | 1 |
Clay-sand mortar
Clay-sand mortar can be called the main one, since it is on it that most of the furnace is laid. This material is the most affordable, even if you have to buy it in a store. But, as a rule, its components can be found literally under your feet, and if a decision is made to extract clay on your own, then it will cost almost nothing.
Clay mortar interacts well with fired bricks, also made from clay, and has special qualities that are ideal for laying a stove:
- average strength;
- heat resistance up to 1100 degrees;
- absolute fire resistance;
- maximum gas density, that is, the ability to resist the penetration of gases into the thickness of the substance;
- all the mortar on which the laying was carried out, except for the furnace one, can be reused;
- the ready-made mixture of clay-sand mortar is suitable for work for an unlimited time after its mixing, as it can, if necessary, be diluted with water and mixed again.
The disadvantages of this solution include its low moisture resistance, so it is not recommended to use it for building a foundation and building a chimney.
The proportions of clay and sand for the solution are determined depending on the fat content of the first, using the methods described above.
Well-infused soaked clay is qualitatively mixed with a shovel or by trampling, that is, with feet. The mass should turn out to be absolutely homogeneous, without lumps or individual inclusions. In the process of mixing the main ingredient, sifted clean sand is gradually poured into it, and a little water is added as necessary. In the end, the solution should turn out to be plastic, easy to slide off a clean and smooth trowel.
In addition, the mixture must be immediately checked for adhesion - for this, the solution is applied to the soaked brick in an even layer 5 mm thick, and a second brick is laid on top of it, which is gently pressed. After 30 minutes, you can check how well the adhesion of the two bricks has taken place. If the solution turned out to be of high quality, then the lower brick should hold on to the upper one even if you keep the structure suspended.
The correct consistency of the solution is checked as follows:
- A clean trowel soaked in water is lowered into the ready-mixed solution of normal consistency, and if the solution sticks to it, then the clay is too greasy. In this case, you need to add a little sand to the mixture, and then mix it again, and test again.
- If the solution is made in a normal consistency, but after lagging behind without stirring, after some time water came out on the surface, then the mixture has a low fat content, that is, it turned out to be too lean. You can fix such a solution by adding more oily or ordinary clay to it, thereby changing the proportions of materials, that is, reducing the amount of sand in its composition.
- If the fat content of the solution is normal, but when a clean trowel is lowered into it, the mass does not stick to it at all, then you need to make the mixture more plastic by adding a small amount of oily clay.
Video: a good example of the preparation of a clay-sand mortar
Clay-chamotte mortar
This solution has increased heat resistance and is able to withstand temperatures up to 1200 ÷ 1300 degrees, so it is used for laying the combustion chamber, where it will be under the constant influence of high temperatures. Since the main component in the solution is clay, it can also be used after kneading for a long time, if necessary, adding water to the composition.
When preparing a mortar for laying the walls of the combustion chamber, the following materials are used:
- Clay. Gray, white or fireclay clay with normal fat content can be used here.
- If the fat content is too high, it is thinned with a mixture of quartz and fireclay sand, taken in a 1: 1 ratio.
- If a furnace with a moderate heat load is being built, for example, a Dutch, Russian or ordinary hob, then a solution of refractory clay can be used for laying the firebox, without adding sand.
In the case when the solution is made up of two ingredients, 30% refractory clay and 70% fireclay sand are taken. Its kneading is carried out in the same way as the clay-sand composition:
- Clay is cleaned and soaked for 2-3 days, then thoroughly mixed.
- Sand is gradually poured into a well-mixed mass, and the entire solution is kneaded until smooth.
- Water is added to the solution as needed.
It should also be taken into account that if the furnace is completely built from refractory fireclay bricks, then the solution is made from refractory clay and fireclay sand in proportions of 3: 1.
Lime mortar is made from lime paste and sand, in a ratio of 1: 2; 1:4 or 1:5, depending on lime fat content. This composition will cost more than a clay-sand mortar, since slaked lime will need to be purchased at the store.
The finished solution is usually used for laying out the first two rows in the order of the furnace. It has the following characteristics:
- fire resistance and heat resistance are below average, since it is able to withstand heating no more than 450 ÷ 500 degrees;
- strength is higher than that of a clay mixture;
- the gas resistance parameter is lower than that of clay;
- The solution is non-hygroscopic, meaning it does not absorb moisture.
Lime mortar should be used within three days after mixing, since then it will irrevocably lose a number of its positive qualities, and the masonry on it will become unreliable.
Lime mortar is mixed in the following order:
- The lime dough is placed in a container, water is added to it, and then the contents are kneaded until smooth, approximately to the consistency of thick sour cream.
- The next step, this composition is passed through a metal sieve with cells no more than 2 ÷ 2.5 mm. Large elements of sediment remaining on the surface of the sieve can be gently rubbed through the mesh.
- Further, sand is introduced into the solution, according to the proportions, and the mixture is thoroughly mixed again.
It is very important to remember that it is impossible to use quicklime for the manufacture of mortars, since, having reacted with water, it can tear the seams of the masonry.
Cement-sand mortar
The cement mortar is made from M400 cement and purified, sifted sand, in proportions from 1: 3 to 1: 6, depending on the application of the composition.
This material is the most popular, although it has a fairly high price. It is characterized by high strength and reliability, but it is not recommended to use it for the construction of the entire furnace, since it does not have the “mobility” necessary for this structure, unlike clay and lime mortars. Typically, a cement-sand mortar is used to equip the foundation and the chimney section located outside the building.
Such a cement-sand mixture is able to harden and gain strength both in the air and indoors. She is not afraid of high humidity and begins to set in any conditions after 40 ÷ 45 minutes after kneading. Complete hardening and maturation of the laid out mortar occurs in a period of up to 28 days, depending on the thickness of the layer and the area of \u200b\u200buse of the material.
For example, a foundation deepened by 500 ÷ 600 mm into the ground will be ready for the construction of a furnace no earlier than in a month. It will take much less time to dry the joints in the brickwork, since their thickness will be only 5 mm.
For the manufacture of masonry mortar, proportions of 1: 5 are taken, and for the construction of the foundation - 1: 3. Preparation is carried out in the following order:
- In the container where the solution will be mixed, sifted sand and cement are placed in the required proportions, and then this mixture is well mixed in dry form.
- Further, water is gradually added to the finished mixture with constant stirring. The solution should have the consistency of thick sour cream, so you should try not to pour excess water into the mixture. If this happened, and the solution turned out to be too liquid, then a small amount of dry cement is added to the mass, and it mixes well again.
If the application of the cement slurry requires strength, but less rigidity, then compositions are used in which the cement works in "tandem" with other materials.
The cement-chamotte mortar is kneaded in the same order as the cement-sand mortar, but differs from it in its qualities, which allow it to be used to build the walls of the combustion chamber.
Such material has a rather high price, but this is sometimes justified, since the resulting mixture has special characteristics:
- the heat resistance of the solution is comparable to the clay-chamotte composition;
- fire resistance is average, but quite sufficient for use when laying the combustion chamber;
- high gas density, comparable to clay mortar.
After mixing, the mass must be worked out within 40–45 minutes, since then the cement sets and the mortar quickly loses its original qualities.
Cement-lime mortar
This solution will be somewhat more expensive than lime, but it will also be much stronger, and a very small amount of cement is added to the total mass.
Cement-lime mortar is made from cement, lime paste and purified sand. Materials are taken in different proportions, but when using cement grade M400, they usually take a ratio of 1: 0.2: 3. This solution is used infrequently, and some masters lay on it, basically, only the first two rows of ordering.
Table of proportions of materials, depending on the brand of cement and the desired brand of the resulting solution:
Grade of cement | Brand of cement-lime mortar, consisting of three materials - cement, lime and sand. (kgf/cm²) | |||
---|---|---|---|---|
100 | 75 | 50 | 25 | |
600 | 1: 0,4: 4,5 | 1: 0,7:6 | - | - |
500 | 1: 0,3: 4 | 1: 0,5: 5 | 1: 1: 8 | - |
400 | 1: 0,2: 3 | 1: 0,3: 4 | 1: 0,7: 6 | 1: 1,7: 1,2 |
300 | - | 1: 0,2: 3 | 1: 0,4: 4,5 | 1: 1,2: 9 |
Cement-lime mortar cannot be used in other areas of the furnace, since it can only withstand temperatures up to a threshold of 220 ÷ 250 degrees, and also has a very low gas density.
This solution is suitable for work within 45÷60 minutes after mixing. In the future, it begins to harden and becomes less elastic, so you should not knead a large amount of the composition - it is better to cook it in small portions.
The cement-lime mortar is mixed in the following order:
- The lime dough is diluted with water to the consistency of thick sour cream and mixed until smooth.
- Dry cement is mixed with sand.
- Then, the dry mixture is introduced into the lime mortar in a thin stream, with continuous stirring. It is better to work together here - one pours the cement-sand mixture, and the other thoroughly mixes all the ingredients.
Separately, it is necessary to say a few words about the lime test. It is made from slaked lime - this material is sold in hardware stores, as a rule, in hermetically sealed packages. You should not save on this ingredient when buying a quicklime composition, since bringing it into the desired state is a rather laborious and, to a certain extent, even dangerous process. And by doing the slaking of lime incorrectly, you can further spoil the laying of the lower rows, on which the reliability of the entire furnace structure depends.
What is the general conclusion? Before starting work on the construction of the furnace, it is necessary to think over everything well and make a list of all the required materials that will be required for high-quality masonry. Adhering to the recommended recipe and technology for mixing solutions, it is quite possible to prepare them yourself, saving a decent amount on this.
You may be interested in information about what is on wood
Prices for masonry mix for stoves
masonry mix for stoves
And at the end of the article - another recipe for preparing masonry mortar, as advice from a practicing master stove-setter. you can find out from the link.