How and from what it is better to prepare a mortar for laying a stove

Brick ovens somehow quickly gained their former popularity. There are more and more people who want to have this structure in their home. But the topic of today’s article affects the stoves themselves indirectly. We will be interested in the question of how to prepare a mortar for laying a stove.

Mortar for laying a brick stove Source remontik.org

Classification of furnace solutions

Firstly, we must immediately make a reservation that the construction of a furnace requires three types of masonry mortar. And that's the minimum. However, these solutions cannot be mixed like ordinary cement-sand ones.

The thing is that the stove consists of three structural elements: the foundation, the stove itself with a firebox, and the chimney. Now imagine that the foundation must withstand quite serious mechanical loads. And most often in winter its temperature is 0°. In the firebox the temperature reaches up to +1000C, and the chimney located outside is constantly exposed to low temperatures. Now it is clear that ordinary cement mortar will not withstand such varied loads.

Secondly, today the building materials market offers ready-made mixtures. It would seem very convenient. Add water according to instructions and apply. But let's look at the economic side of the issue.

Ready-made oven mixtures Source applesakhalin.ru

Laying one hundred bricks will require three buckets of mortar. And 100 standard brick blocks are not enough for half the cooking surface of a regular summer kitchen. Not to mention the foundation and chimney. That is, you will have to purchase a fairly large number of bags of dry mixture for ovens from the store. And the prices for this material are considerable. So think about how to prepare a solution for laying a clay stove without buying ready-made mixtures. It will cost many times less.

Understanding the terms

In the kiln business, three terms are used in relation to masonry mortars:

1. Heat-resistant solution. This material can easily withstand heating to fairly high temperatures. And when cooled, it does not crack, does not deform, does not change its structure, and maintains a high design load-bearing capacity.
2. Heat resistant. Such a solution can easily withstand dynamic loads in a heated state. It retains its mechanical characteristics during temperature changes. But the magnitude of thermal deformations is slightly lower than that of the heat-resistant version.
3. Refractory. It absorbed all the characteristics of the two previous types. But at the same time, it easily tolerates the negative effects of chemically aggressive substances. This refers to waste carbon monoxide that passes through the firebox and chimney.

Now the question is what kind of mortar is needed for laying the stove. The answer is heat-resistant and fire-resistant.

Heat-resistant oven mixture for masonry Source catalogue.brick-concrete-concrete.rf

But as for the foundation, such a complex solution is not needed here. The thing is that this part of the structure is practically not subject to serious temperature fluctuations. After all, the foundation itself is a concrete monolithic structure on which two rows of bricks are laid. This is exactly what we are talking about. For their laying, ordinary cement-lime mortar is suitable. The main thing is to use red solid brick for masonry.

Now about the body of the furnace, or as it is called, the heat-storing part. In essence, this is a stove made of red solid brick of the M150 brand, inside of which there is a firebox. The latter folds separately, and more about it below.

So, in the heat-accumulating part of the structure, the heating of the bricks is small - up to +600C. But it is here that the bricks are exposed to intense exposure to carbon monoxide and acidic condensate. For masonry it is better to use ordinary clay mortar. Let’s immediately say that this mixture is simple in composition, the preparation method is specific. More about him below.

Next is the firebox, which is assembled from fireclay bricks. Here the temperature reaches +1200C, so a fire-resistant mortar is used for masonry - clay-clamotte.

Chimney mortar - lime Source i1.ytimg.com

Now the chimney consists of several parts:

1. Source. Here the temperature does not rise above +400C, so the brick and mortar are exactly the same as in the heat-storing part of the furnace.
2. Fluffing is a transition through the ceiling of a house. Temperatures in this part are low, but a certain structural strength is required. Therefore, for masonry we choose solid bricks and lime mortar.
3. Chimney located in the attic and above the roof. High temperatures have no effect here. But there are special requirements for strength, especially for the external part. Because it is affected by wind loads. For construction you will need ordinary red brick and lime mortar.
4. Pipe fluffing . Everything here is the same as in the previous paragraph.

Please note that each part uses its own brick and mortar. This is what allows you to save a lot on the purchase of building materials.

No. 4. Clay-fireclay mortar

It is recommended to use clay-chamotte mortar for laying the firebox allow the use of ordinary clay mortar when building stoves with a not very intense thermal regime: these are Dutch and Russian stoves, hobs, and barbecues.

In other cases, you will need gray, white or yellowish clay with high fat content. It is thinned with fireclay sand, but more often, to save money, a mixture of quartz and fireclay sand is used in a 1:1 ratio. Soft water must be used, with a hardness of up to 160 mg/l. The preparation is no different from ordinary clay mortar with one caveat - strength tests are not needed, because it is provided by the original raw materials.

A few words about fireclay

The question of what kind of solution the stoves are placed on involves one material that many consider to be a mineral. This is fireclay. We must immediately make a reservation that this is a mixture of high-alumina clay and several minerals: garnet, zirconium and others.

Fireclay is produced by deep firing of the prepared mixture. In this case, they burn even after complete removal of water from the mixture. The main task of the technology is to pelletize and sinter the components.

It is this material that is used in the process of making fireclay bricks, where the first one performs the functions of sand. For household stoves, bricks with a water absorption of 15-20% are suitable. As for solutions, here you can use fireclay in the form of a mortar - this is an unshaped mass. Or in the form of broken fireclay bricks, which are sold on the market as sand or crushed stone. Mortar is better.

Mortar is an unshaped mass of fireclay Source i.stroy-ka.ru

See also: Catalog of projects of houses with a stove for permanent residence

What tools will you need?

Before you start preparing solutions, you need to select a tool:

• a kneading oar (a specially hewn board with a handle);
• shovel;
• container for mixing the solution (a wooden trough or barrel, or a metal container);
• 5-6 buckets;
• trowel, which determines plasticity;
• a pair of metal sieves with 3x1.5 mm cells;

After the tool is prepared, you will need to prepare the components for the solution.

Properties of masonry mortars for furnaces

Before making a mortar for laying a stove, you need to understand that the properties and characteristics of the mixtures mentioned above determine their place of purpose in the stove structure. Therefore, more specifically about them:

• Clay. This is a cheap material that can cost you nothing if you find the right clay. But kneading it is a labor-intensive process. Here are the characteristics of the solution: strength and heat resistance are average - up to +1100C, fire resistance - absolute, maximum gas density. Can be used if the stove is built indoors.
• Lime. To prepare, you need to know one important nuance - you use lime that is slaked completely to the last grain. If this is not done, then there is a high probability that these grains will create conditions for the appearance of cracks in the masonry. And this reduces the quality of the seam. As for the characteristics, then: fire resistance and heat resistance are below average, strength is above clay. The solution is not hygroscopic, so it can be used for stoves built outdoors.

Clay mortar for the oven Source www.diy.ru

• Cement-lime. Used to lay the foundation of the stove. Strength is high, gas density is low.
• Clay-fireclay. Exactly the same characteristics as clay, but higher heat resistance - up to 1200C. Used in the construction of fireboxes.
• Cement-chamotte. This is the most expensive solution of all, because only high-quality materials must be added to it. As for the characteristics, there is a difference: strength is comparable to cement-lime, heat resistance is like clay-fireclay, fire resistance is sufficient for combustion chambers.

Let us immediately make a reservation that all these solutions are difficult to mix by hand.

What parameters are affected by the mixture for laying bricks?

A mixture of poor quality or inappropriate for operating conditions can cause very unpleasant consequences. The stove will either have to be constantly repaired, or completely redone taking into account the mistakes made.

The quality of the solution affects the safe operation of the furnace

How does a poor-quality masonry mixture manifest itself?

1. Cracks in masonry joints. They are most quickly detected in places of maximum heating. The presence of cracks indicates that the strength of the furnace has decreased significantly.
2. Smoke enters the room. A very dangerous phenomenon that requires immediate elimination. In winter, the stove is not dismantled; cracks have to be periodically sealed with mortar throughout the season. After a few days it falls out and the process needs to be repeated.
3. The bricks are shaking. Such consequences are found near the firebox doors. Heavy cast iron structures are connected to bricks. If they are not strong enough, then the doors will wobble a lot when opening/closing. With such a problem, you can hold on to the heat, but you need to use the firebox very carefully and carefully.

If you use a low-quality solution, you will subsequently have to repair cracks in the slab

Video description

The video shows how to prepare a clay mortar for laying a stove:
What is gas density - this is a characteristic of a solution, which shows that dense gases from fuel combustion cannot pass through the thickness of the applied mixture by diffusion. It should be noted that gas density is not hygroscopicity. The thing is that water vapor is more mobile, so it easily passes through the material. Hence the concept of “breathable” structures. For example, a cement-sand mortar does not allow vapor to pass through when it dries. But carbon monoxide still passes through it. Therefore, it is very important that the solutions used in the construction of furnaces must be selected in accordance with both hygroscopicity and gas density.

Characteristics of solutions and their production

In addition to knowing the characteristics of the individual component materials, it is necessary to have information about what effect is obtained when they are mixed, that is, about the characteristics of the finished solutions, as well as about the technology for their preparation.

Table of consumables for making the most commonly used mortars for laying stoves:

Clay-sand mortar

The 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 the store. But, as a rule, its components can be found literally under your feet, and if you decide to extract clay yourself, then it will cost practically nothing.

Clay-sand stove mortar

Clay mortar interacts well with baked bricks, also made from clay, and has special qualities that are ideal for laying a stove:

• medium 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 masonry was made, except for the furnace, can be reused;
• The finished mixture of clay-sand mortar is suitable for use for an unlimited time after mixing it, since 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 constructing a foundation and constructing a chimney.

The proportions of clay and sand for the solution are determined depending on the fat content of the former, using the techniques described above.

Well-infused, soaked clay is thoroughly mixed using a shovel or by trampling, that is, with your feet. The mass should be absolutely homogeneous, without lumps or individual inclusions. While mixing the main ingredient, sifted clean sand is gradually poured into it, and a little water is added as needed. Ultimately, the solution should be plastic and easily slide off a clean and smooth trowel.

In addition, the mixture must be immediately checked for adhesion - to do this, the solution is applied to the soaked brick in an even layer 5 mm thick, and a second brick is placed on top of it, which is gently pressed. After 30 minutes, you can check how well the adhesion of the two bricks has occurred. If the mortar is of high quality, then the lower brick should remain on the upper one even if the structure is suspended.

Checking the consistency of the mixed solution (from left to right): too dense, too much water, optimal

The correct consistency of the solution is checked as follows:

• A clean trowel soaked in water is lowered into the prepared 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 run the test again.
• If the solution is made in normal consistency, but after leaving without stirring for some time, water appears on the surface, then the mixture has low fat content, that is, it turned out to be too lean. Such a solution can be corrected by adding fatter 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 you lower a clean trowel 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 fatty clay.

How to choose the right components

How to make a mortar from clay for the stove so that it does not crack. It is clear that the quality of the final result always depends on the components of the mixture. Therefore, we will deal with each separately and outline some of the nuances of choice.

See also: Catalog of companies that specialize in installing stoves, fireplaces and equipping gazebos and grill houses

Clay

This is the main component. It is found in large quantities on any private plot. But here the question arises: is all the clay suitable for laying a stove? Moreover, when choosing this material in one place, you may encounter several of its types, arranged in layers. So what kind of clay is needed?

Fatty fireproof clay Source www.banikaminy.ru

Let us immediately make a reservation that all the above-described characteristics of solutions: strength, hygroscopicity, gas tightness, and so on, are determined by the properties of the clay. And the main property of the latter is fat content. Furnaces require material of medium fat content. Very oily clay cracks when dried, thin clay has low strength. For information, fat content is determined by the quantitative ratio of sand and two elements: silicon oxide and aluminum. Of course, organics also contribute their own characteristics.

Attention! If oily clay is found on the site, then it’s not a problem. It can be thinned by adding sand.

How to determine fat content. This can be done without laboratory tests. This will require a piece of material less than half the size of a fist. It must be kneaded with wet hands until it becomes plastic. Then the ball is placed between flat plates, for example, two planks or pieces of sheet iron. Pressure is created until the test sample cracks. Now the thickness of the resulting cake is measured. If this parameter has decreased by 1/3 of the diameter, then such clay can be used in kiln making.

And one moment. Not everything that comes across the site can be considered clay. There are so-called deception minerals that are very similar to clay. For example, bentonite, shale, marl and others.

How to save on masonry materials?

The answer to this question would seem to be quite obvious: it is necessary to make maximum use of available materials, which can be obtained for free right at the site of construction of the furnace. In our case, we can independently obtain the following components: clay, sand and water. But, as practice shows, in reality everything is far from so simple. You can’t just take any water, mix it with the first available sand and clay, and as a result get a good quality mixture for masonry. A number of serious requirements are put forward for each component for creating a stove mortar. Let's learn more about each of them and learn how to select all the necessary components.

How to distinguish high-quality clay suitable for laying a furnace from other minerals?

Quite often, broken clay can be purchased cheaply from local stove makers, but we do not recommend that you take the easy route. Such material is usually heavily contaminated with organic impurities. Subsequently, they will rot and decompose, worsening the consistency of the mixture and the quality of the finished joints. It is much more profitable to find good clay in the surrounding area and dig it yourself. The difficulty lies only in learning to distinguish high-quality deposits from contaminated ones.

Clay is essentially a mixture of aluminum oxide Al2O3 and silicon oxide SiO2 (in simple terms, sand). The main determining parameter for clay is its fat content. In turn, the strength of its structure, plasticity, adhesiveness (ability to stick to other surfaces), hygroscopicity and even gas tightness will directly depend on it. Typically, the fat content of clay containing 62 percent aluminum oxide and 38 percent sand is taken to be 100%, and the fat content of pure sand without impurities is taken as the zero reference point - 0%. To mix the mortar for laying the stove, we will need clay with average fat content, because seams made from material with too high a fat content will crack during drying. “Low-fat”, or as it is also called, “skinny” clay is also not durable.

Clay deposits of various types

Clay has several fossil twins that are often confused with it. However, furnace work with other mineral materials is impossible, so it is important to be able to distinguish them from what we need.

Shale and marl. The material is a brittle rocky rock. It lies in horizontally arranged layers that are visible to the eye and have rounded edges. In addition, if you take a sample of shale and break it, the shale structure will be clearly visible on the resulting section.

Appearance of shale

The greatest difficulty in identification is caused by bentonite, also known as bentonite clay ( bentoclay ). This is a valuable mineral resource, but it is completely unsuitable for use in the furnace business. Sometimes bentonite is found in bright colors, virtually identical in appearance to the clay we need.

Bentonite clay, consisting of sodium-calcium compounds, montmorillonite and other impurities, has found its use in pharmacology, medicine, perfume production, winemaking and even in mining. The uniqueness of this mineral compound lies in its ability to absorb moisture. Bentonite saturated with water can increase in volume by one and a half dozen times without consequences, turning into a gel-like state. But, unfortunately, it does not have the properties of ordinary clay, such as fire resistance, gas tightness and heat resistance. It is quite simple to distinguish benthoclay from the building material we need. It is enough to take a small test sample and place it in a glass filled with water. After a short period of time, bentonite will absorb moisture and noticeably increase in size. After waiting a sufficient period, you will be able to witness the transformation of the sample into a bentonite gel, which looks like a jelly, somewhat similar to jellied meat. Clay in water will not turn into anything like that.

Appearance of bentonite clay

In the figure below you can see a schematic cross-section of the soil structure characteristic of our country. Clay located in the upper layers of the earth is highly contaminated with organic impurities. On top, the main layer of clay deposits is covered with so-called loam - a layer of soil with a significant admixture of alumina and sand. In the diagram, loam is indicated in yellow. Actually, the main layer of clay has uneven fat content: at the top it is minimal and grows as it goes deeper into the soil.

Layout of clay layers

We will determine the fat content of clay using a special test. Raw materials for analysis must be collected after passing through a layer of loam. In this situation - starting from five meters from the surface of the earth.

The clay test itself is very simple: we pick up a lump of material the size of half a fist. We wet our hands with water and begin to knead it like plasticine, gradually giving the sample the shape of a ball.

Test ball rolled from clay

After the ball is ready, we begin to slowly press it with two flat boards on both sides exactly until the first cracks form. If you managed to compress the ball by at least a third of its diameter, then such clay is quite suitable for our tasks. We take about five more kilograms of material in a bucket and take it home for further tests, which we will talk about later.

Testing a clay sample using boards

How to find high-quality water used in mortars for masonry stoves

It is necessary first of all to check the quality indicators of the water that we plan to use to create the stove solution. Only so-called “soft” water, or at least water with medium hardness, is suitable for work. Hardness is measured in units called German degrees. One such degree means that each liter of water being tested contains 20 milligrams of calcium and magnesium salts. Kneading the stove solution can only be done if the water hardness is below ten degrees.

What sand is suitable for laying a stove? Sand preparation

As for sand, there is no need to take samples. Near clay deposits you can always find layers of white quartz sand and yellow sand containing feldspar. The first is suitable for creating any stove structures, and the second can be used in the laying of all elements except the hottest part - the firebox. Remember that preparing sand for use will require a significant amount of water. That is why you should take care in advance to resolve issues regarding uninterrupted water supply.

Sand dug up on your own must first be passed through a sieve with a mesh size of 1-1.5 millimeters. This allows you to get rid of various large debris and obtain the necessary set of fractions. The biggest problem for self-dug sand is organic impurities and various living microorganisms living in it. The sand must be cleaned from them, otherwise the masonry seams may deteriorate over time.

Sifting sand with a sieve

There are many industrial methods for cleaning sand, but they all involve significant energy costs. In order to save money, we will use a simple and accessible washing method for everyone.

To make a cleaning apparatus, we need a piece of pipe 15-20 centimeters in diameter. Its height should be approximately three times its thickness. We fill a third of the volume with sand and supply water from below under high pressure. The power of the water jet must be selected in such a way that the washed sand swirls, but does not flow into the drain located on top. After clean water flows into the drain, wait about ten minutes more and finish the procedure. The first batch of purified sand is ready. All that remains is to dry it.

Scheme of a sand washing apparatus

The method of filtering sand by washing also allows us to remove from it various inclusions of alumina that we do not need.

Proportions of mortar for laying a stove, how much sand, water and clay should there be?

An important step in preparing a construction kiln mortar is to determine the optimal proportion between sand and clay. After we bring home the clay sample selected according to the algorithm outlined above, it is necessary to divide it in two. We set aside the first half, and divide the second again into five identical pieces. We place each of them inside a separate bowl and add water (hardness up to 11 German degrees), about a quarter of the volume of the clay itself.

Next, we leave the clay to liquefy in the water. Typically, this process takes approximately 24 hours. After a day, stir it thoroughly and pass it through a sieve with a mesh size of three millimeters to sift out large lumps.

Clay dissolving in water

Place the container with the strained solution back to settle. When a cloudy slurry (the so-called “sludge”) appears on the surface of the solution after settling, remove it by pouring it onto the ground.

That's it, now you can start adding sand to each container with prepared clay. This must be done in the following proportions:

• First container - do not add sand;
• The second is one part sand to four parts clay;
• Third - two parts sand to four parts clay;
• Fourth – 3 parts sand and four parts clay;
• Fifth - sand and clay are added in equal quantities.

Adding sand to each container must be done gradually, in small portions, in several approaches (optimally - no less than three and no more than seven). Everything needs to be mixed very thoroughly. Do not rush to add the next portion of sand before the previous one has completely and evenly dissolved in the mixture. A well-mixed clay-sand solution is quite easy to identify: just try rubbing it between your fingers. If the roughness of individual grains of sand is not felt, then everything is done correctly.

Add sand to the clay

The next step in preparing the clay-sand mortar will be the production of prototypes. We take clay in each of the five containers and alternately do:

• Two bundles of approximately 35 centimeters in length and a centimeter and a half in diameter;
• We fashion a ball with a diameter of five centimeters;
• A round clay cake with a thickness of 12-15 millimeters and a radius of 7.5-8.5 centimeters.

As a result, we will have exactly 20 samples on hand that need to be marked and left to dry inside the building. For normal drying, samples should not be exposed to drafts or direct sunlight. Usually the ropes dry out in a couple of days, but cakes and balls can take up to two dozen days. If the ball does not wrinkle and the cake no longer bends in half, it means the material has completely dried.

Clay ball and cake

When the samples are ready for testing, we proceed to the next classic experiment, which allows us to determine the fat content of the clay solution. To do this, wrap a clay rope around the handle of the shovel, then tear it apart and observe the results:

• The greasy clay, indicated in Figure G (from the German “greesy” - greasy) will practically not crack, and when the rope is torn in half, the break point will have teardrop-shaped ends.
• Clay of normal fat content (marked as N) will have a cracked top dried layer and, after breaking the rope, its thickness at the point of separation will be approximately a fifth of its original thickness. These are the samples we need to select.
• Dry (lean) clay, designated as L (from the German “Lean” - lean), will be marked by the maximum number of deep cracks and, when broken, will have the largest area where the pieces of the rope separate.

As a rule, after selection, several (usually 2 or 3) seemingly suitable samples remain.

Determination of clay fat content

Dried balls and cakes will help us carry out the final “clay casting”. We drop samples from a height of a meter above the bare floor. The most durable of them will indicate the required consistency of sand and clay. If, after falling from a meter, all samples remain intact, we begin to gradually increase the height until we can determine the strongest of them.

Checking a clay-sand mortar using a flat cake as an example

Checking the quality of a clay-sand mortar using a ball as an example

The next step in preparing the mortar for laying the stove will be to calculate the required ratio of water to the proportion of sand in the mixture. The physical limits within which a clay mixture will have normal fat content are quite wide. Our main task, since we are building the stove for ourselves, is to make the strongest possible structure, with excellent gas tightness of the connecting seam material.

First of all, we sift the clay remaining during the test sampling. Press the clay through a fine mesh sieve so that it mixes evenly with the sand. Add the required amount of prepared washed sand. We learned the proportions of sand and clay earlier thanks to experiments. We start adding water and gradually mix the solution. Remember that the water must meet the hardness parameters that we talked about earlier.

Next, we take a trowel in our hands and make a depression on the surface of the mixed solution.

The mark from the trowel (trowel) will help determine the readiness of the solution

• A tearing hollow indicates that there is not enough water (Fig. 1)
• If the hollow immediately behind the trowel begins to float, it means you have overdone it with water (Fig. 2). Let the solution settle and remove the sludge into a separate bowl. The difference in volume between the filled water and the squeezed out sludge will show us the required optimal proportion.
• If you immediately guessed the required amount of water, the trowel will leave a clear, clearly visible, even trace with highlighted edges on the surface of the mixed solution (Fig. 3).

Proportions and proper preparation of clay mortar, testing for strength

The so-called cross test will allow you to find out whether our clay solution will be sufficiently strong and have the required degree of adhesiveness. This final test will show how accurate the results of all our preparatory checks on the material were and how well we cleaned the constituent components of the oven mixture.

To test, we need a couple of bricks, one of which we place flat on the ground and cover its largest plane (the so-called “bed”) with a thin layer of prepared test clay mortar. Place a second brick on top and, tapping it with a trowel, let the mixture dry for about ten minutes . After this, we grab the brick located on top with our fingers and pull it up. Having raised it to a certain height, we shake the structure by weight: if the bottom brick does not come off, it means that all the preparatory work was carried out carefully and we correctly calculated all the proportions of the clay mortar.

If you still do not understand the individual details of preparing mortar for laying a stove, we recommend that you watch this video:

Proper preparation of mortar for laying a stove: video tutorial

Video description

The video shows how you can determine the fat content of clay:

Sand

This building material is another component of masonry mortar for stoves. What sand can be used in this case:

• white quartz
• yellow , it consists of feldspar, suitable for all parts of the stove except the firebox.

If you buy sand on the market, then the best option is sifted sand of different fractions. It is this that creates the high strength of the masonry.

Now let's look at the question of how to make a mortar for the oven so that it does not crack, from clay and sand. To do this, you will have to conduct an experiment, for which you will need clay - 5 pieces. We add sand to four of them in different proportions: 25%, 50%, 75% and 100%. The solution must be mixed well. We leave one in the form of pure clay.

From these pieces, sausages of 30-40 cm are made, which are screwed, for example, onto the handle of a shovel. Then you need to wait until the samples dry. Sausages made from fatty clay do not crack, or only the top crust cracks. Samples made from lean material will crack completely, falling apart into pieces.

River sand for clay mortar Source www.diy.ru

No. 6. Cement-lime mortar

Cement-lime mortar is even stronger than lime mortar, and you will need absolutely no cement, and the higher its grade, the less it will be used. You will need a ratio of cement, dough and sand of 1:2:10. First, water is added to the lime dough, mixed and cement is added, without stopping stirring, then sand is added and the solution is mixed. It is better to determine the exact quantities of sand and water in a small test batch.

Solution preparation technology

Which mortar for laying a stove is better - homogeneous. Therefore, it is very important to knead it correctly. Especially when the process is carried out using small-scale mechanization. The thing is that during the process of mechanical kneading, so-called gaps may appear inside the mixture. These are areas with a lot of clay milk. The latter will subsequently resolve, but the homogeneity of the material will be disrupted.

Some craftsmen beat clay. There is no need to do this for ovens. The main task is to strictly follow the technology. And it's simple:

• sifting components;
• mixing components;
• settling the resulting solution.

Kneading is usually done with shovels. Here it is important to carry out the operation until the mixture is completely homogeneous.

How to get clay

To get by on a budget, you should first stock up on clay and sand. With their help, they not only make solutions, but also regulate plasticity. When the furnace part is laid out, clay will be needed. What is she? This is a material created by nature itself, very plastic when saturated with water. Varies in fat content. If it contains more than 40 percent sand, it is skinny. It is not suitable for laying stoves in its pure form, since the seams will be fragile. The normal sand ratio is 37-38 percent. When there are fewer of them, the clay is normalized by mixing regular or fireclay sand.

Where can I get clay for laying a stove? There are several methods:

1. Unfired factory raw brick is soaked by dipping it in a container of water. The softened mass is filtered using a fine mesh sieve. Then sand is mixed in. The desired consistency is obtained by adding the required amount of water.
2. Sometimes local clay is sold very inexpensively by local residents. But this is very dirty clay, it will have to be cleaned and expressed several times.
3. You can extract clay yourself. Its deposits are found almost everywhere. If you go 4-5 meters deep, you can dig it up in your own garden. But it’s even better to look for clay on river banks, in ravines and other places where the soil has been washed away. In the section of banks and ravines, clay is usually visible in a single layer. Approximately 5 meters are measured from the surface and a piece of rock is broken off for testing. If you crush a lump, it should crumple like plasticine and not stick to your hand. You can try rolling it into five-centimeter flagella up to 5 mm thick. If they bend in an arc and do not break, then it looks like clay. If not, then you can look in another similar place.

On a note. You need to know that colors may vary. It depends on mineral inclusions. And this does not affect the quality of the clay. It is believed that the best clay is white, that is, kaolin. It is used to prepare a clay mixture when laying the firebox.

Gray, bluish-gray and greenish-gray breeds are more common. But there is clay in brown-chocolate and earthy shades. This indicates that the composition contains iron oxides, which give this color.

Experienced stove masonry masters not only know how to prepare clay for laying a stove, but also determine its suitability immediately, without laboratory testing. But novice craftsmen must test the clay experimentally. To do this, you need to take 5 measurements of clay, half a kilo each (or a kilogram).

How to plaster a brick oven

So, having dealt with the question of what mortar is used for laying a brick oven, we move on to considering another position. Namely, what solution to cover the stove with so that it does not crack.

Firstly, you need to give time for the brick structure to shrink. Secondly, before starting plastering, the stove must be heated. The goal is to expand it in volume. Thirdly, a mesh is laid on the surface, which will strengthen the plaster layer. After which you can proceed to the main process.

The better to plaster. There are many options - these include ready-made mixtures and those prepared independently. The simplest is the clay mortar used for laying. Popular experience shows that it is necessary to add salt and wood ash to it. Two ingredients will not only increase the strength of the mixture, but also increase its heat resistance.

Plaster of a brick oven with a mesh attached to it Source avatars.mds.yandex.net

Before you prepare a solution from ash to putty the stove, you need to prepare all the ingredients. Here the ratio is:

• clay should be twice as much as sand;
• salt is added at the rate of 30 g per 1 liter of clay-sand mixture;
• ash at the rate of 50-60 g per 1 liter.

Practical tips for using the mixture

If you violate the generally accepted rules for laying stoves, then even with very high-quality mixtures you can get an outright defect. What do the professionals advise?

The quality of the furnace masonry depends not only on the mortar

1. The clay should only be mixed with a special mixer; you can never achieve a homogeneous composition manually.
2. The solution can be left for an unlimited amount of time. After drying, water is added and the composition is mixed. This cannot be done with cement-based solutions; once they harden, they cannot be corrected.
3. Work is allowed only at temperatures not lower than +10°C. The bricks must be dry; the rate of moisture absorption does not affect the strength parameters.
4. The first time the stove can be lightly heated no earlier than three days after the completion of the masonry. It is strictly not recommended to rush; if the recommendations are not followed, large cracks may appear through which smoke enters the room.
5. To lay the outer row of the outer chimney, cement should be added to the mixture. Ordinary clay with sand is afraid of moisture and gradually erodes outdoors. Cement mortar does not react to the negative effects of natural precipitation.

For laying the chimney, use a solution containing cement.

Efflorescence may appear on poor-quality seams after the first fire, and white marks may be visible on the surface. This is a very unpleasant phenomenon and is removed over a long period of time. The efflorescence should be carefully scraped off, and then the surface should be trimmed with a damp cloth. Such actions will have to be repeated until the salts are completely eliminated.

How to remove efflorescence from the stove

The work of a stove maker requires not only theoretical and practical knowledge, but also great responsibility. This is one of the few construction works where no assistants are involved; all operations are performed by the master personally and bears full responsibility for the results of his work. Even a slight deviation from the recommended technologies becomes the cause of defects; to eliminate them, you need to lose a lot of time and financial resources.

How to determine the plasticity of clay

To understand how to properly dilute clay for laying a stove, clay samples must be placed in various containers. Add water gradually to obtain a plastic solution that does not stick to your hands, resembling well-kneaded dough. Each sample is marked with a serial number.

Then proceed as follows:

• the first sample is left in its original form;
• 10 percent sand is added to the second sample;
• for the third sample - 25 percent;
• by the fourth - 75 percent;
• to the fifth - the same amount as the volume of clay.

Sand is introduced gradually, in portions, stirring after each addition. When a lot of sand is added, you need to increase the volume of water.

Before soaking clay for laying a stove, you need to determine its quality. As samples, 2-3 balls with a diameter of 50 mm are made from each sample, as well as cakes 20-30 mm thick. Then they should be dried in a place where there is no draft. After ten days have passed, the cakes and balls need to be checked to understand where the best composition is. To do this, each ball is dropped from a meter height onto the floor. It should not break or crumble when compressed. Dried samples should not have large cracks. For the experiments to be successful, it is necessary to prepare several balls of each type of clay to be sure.

There are two more ways. First, each sample is rolled into balls 50 mm in diameter. They are placed under a press, the role of which is performed by two planks. If, after compression, the ball shrinks twice and small cracks appear, the clay is plastic. If shrinkage occurs only by a third of the diameter, cracks will be noticeable; this is clay with medium plasticity. Skinny clay will shrink only one quarter or less, or it will simply crumble.

The next method is with flagella up to 20 mm thick and 250 mm long. They need to be stretched one by one and bent around a wooden rolling pin or a shovel handle (50 mm in diameter). Skinny clay will not withstand the test; the flagellum will immediately break without stretching. With an average degree of plasticity, the flagellum will begin to tear, and the stretching segment will become 20 percent less in thickness. The folds of the “sausage” will crack. The plastic clay will not break off, but will smoothly bend around the handle.

Furnace mortars are made from clay, which has average plasticity. It is not difficult to determine the amount of solution required; its volume is a tenth of the volume of the oven.

Results

1. For furnace structures, you need a solution that can withstand temperatures of at least 1100–1200 C.
2. To build the furnace itself, solutions are prepared from red clay. For the combustion chamber and chimney you need an option made of fireclay and sand. There is no difference between the use of quartz sand and ordinary river sand.
3. The ratio of components in the material depends on the indicators of the components. Fat clay is mixed with 5 parts of sand, lean clay with 2.
4. During production, verification tests are performed. If the solution is sticky, add sand; if it separates, add greasy clay.
5. Other options for masonry - cement, lime-sand, are suitable only for the foundation or the outer part of the chimney.

Terminology

Sand art uses only three terms to name the solution. It is heat resistant in nature. Those. a solution that can withstand fairly high temperatures. When the oven cools, this mixture does not crack and remains in its original form.

Heat-resistant solution refers to a mass that can withstand temperature fluctuations. It is characterized by a smaller amount of thermal deformation compared to the first option.

The refractory solution took away the advantages of the two above substances. At the same time, the appearance of the stove remains the original design, despite the passage of smoke through the chimney and firebox. Based on this, we can draw a conclusion about the solution that is most suitable for laying a stove. Namely, about the heat-resistant and fire-resistant mixture.

How to find sand

Sand is sold packaged or in bulk, already sorted into fractions. But it is possible to obtain it yourself and use it for stove mortar. So, white quartz sand is perfect for laying any areas of the stove; yellow sand cannot be used for the firebox.

On a note. If you decide to buy sand, then it is better to take the mountain or lake version; such a building material is best suited for constructing a furnace and will bind the components of the solution well.

It is recommended to make the seams of the stove masonry about 2-3 mm. Therefore, sand is suitable with a fraction no larger than 1.6-1.8 mm. Craftsmen purchase sand of different grains. It is believed that it grips better.

Where can you dig up sand yourself? In abandoned quarries, ravines, river shallows, along steep river banks. The purest sand is not at a depth of one meter or one and a half meters. Otherwise, you will have to wash it for a long time.

If the sand has foreign inclusions, it needs to be cleaned. To do this, sand is poured into a trough and filled with ordinary water. After this, the mixture is thoroughly shaken. The turbidity and dirt that floats out are drained. And so on until the water is clear. For sifting, take a metal construction sieve with cells of 1x1.5 mm.

How to clean clay from sand at home - how to separate

Before making a solution from loam, the components for it need to be prepared - cleaned. They do this in 2 ways:

1. Dry cleaning - select twigs, debris, leaves from the material. Then it is crushed and filtered through a sieve with a cell diameter of up to 2.5 mm.
2. Wet - the clay is not free-flowing, so they often do it differently: they soak the material, and when it swells, rub it through large cells - up to 3 mm.

Wet cleaning method.

Where is the best place to use the mixture?

Clay building mixtures are necessary when the structure is exposed to different temperatures. Also, their plastic properties are in demand when decorating premises. Both materials are actively used in the manufacture of pottery, but here the mixture used is different.

For masonry and repair of stoves - proportions

The ratio of components is chosen taking into account how much the part of the furnace structure heats up:

1. Clay mortar is used in the construction of a heat-storing area. It heats up to 550–600 C, does not come into contact with flame, and is not exposed to oxides. The fluff and the source of the chimney also do not heat up very much - up to 400 C, although they cool more strongly. The proportions are determined by the plasticity index: from 2 to 5 parts of sand per 1 part of clay.
2. Fireclay solution can be heated to 1200 C and higher. It is needed for laying the combustion chamber. In some cases, the entire stove or fireplace is made of fireclay. The usual ratio is 30% clay and 70% fireclay. But if the clay mixture is oily, the proportions change - 50:50.
3. Rows 1 and 2 of the stove can be placed on a lime-sand option.
4. Cement is not elastic and breaks down under high heat. Mixtures based on it are only suitable for the foundation and chimney cap.

It is possible to replace the fireclay mortar with a cement-fireclay mixture. It is only slightly inferior to fireclay in terms of fire resistance, but it sets very quickly. After preparing the solution, it must be used within 45 minutes.

For plaster - ratio of materials

For finishing work, white and red clay of different fat contents are used. Only the cleanest sand is taken - river, sea, alluvial quarry, fine or medium fraction. The ratio is standard: for high fat content 1:5, for medium fat content – ​​1:3, for lean fat content – ​​1:2. Read about the differences between quarry and river.

The characteristics are selected in accordance with the purpose of the plaster composition. To level the wall and fill defects, you need plaster that fills the unevenness well and sets quickly. It is preferable to take quarry or artificial sand: its grains have an angular shape, are rough and adhere better to the binder component. For decorative finishing, river wood is chosen: its particles have a rounded shape and are more evenly distributed throughout the volume of the material.

For sandblasting work

For sandblasting, only sand or slag is used. The best choice is loose yellow or white quartz. Different jobs require different fractions:

1. Dust-like – with grain sizes up to 0.1 mm. They process fragile surfaces in order to create a matte background or pattern.
2. Average – 0.1–0.4 mm. This is how complex images are obtained on glass and mirrors with varying degrees of dullness.
3. A relatively large fraction with particles up to 1 mm is used to obtain three-dimensional images.

For construction work

Materials are the basis of almost all building mixtures and artificial materials. Red brick is made by firing clay, mortar and concrete contain either sand or kaolin minerals, and the finishing always includes one of the materials. Read about the technical conditions for quicklime lump lime in this article.

The laying mixture is selected based on the properties of the material and the nature of the work. Silicate stone is placed on cement mortar, and red stone is placed on clay-sand mortar. The reason is the correspondence of thermal and strength characteristics.

Why do problems arise with the mixture?

Preparing a clay solution for a stove is extremely simple, however, at the slightest violation of the technology or composition, the walls crack, allow smoke to pass through, and do not transfer heat. Main reasons:

• Wrong choice of composition - the stove is made of special refractory bricks - fireclay and red clay. These materials have certain thermal conductivity coefficients. If the masonry mortar has a different coefficient, the stones and mixture in the joints will change volume differently. As a result, the walls are destroyed. For laying stove structures, only clay mortar is used. Cement or gypsum are not suitable.
• Incorrect ratio of components - the amount of sand and clay in the solution depends on the characteristics of the ingredients. There is no strict ratio. If the clay, for example, is very oily, add more sand; if it is thin, add less. This ambiguity leads to mixing errors.
• Non-compliance with technology - the furnace body has a complex structure. Inside there is not only a firebox and an ash pan, but also several smoke exhaust channels. The heated exhaust gases circulate through the channels and transfer more heat. To create this structure, you have to lay the brick on its edge. If the thickness of the seam is changed, this will sharply reduce the efficiency of the furnace.

When preparing the solution, it is allowed to introduce heat-resistant plasticizers. They increase the elasticity of the composition.

Lime and cement mixtures for the furnace

Cement mortar

Mortar using cement
This mixture for laying a furnace is widely used in the DIY construction process. It consists of cement, sand and water . This composition is used in the manufacture of foundations (especially in places with high humidity). Used in laying chimneys above the roof of a building. This composition has the property of hardening in air and water. Setting begins to occur after 30 minutes, and complete drying after 12 hours. It is easy to prepare the mixture for the stove with your own hands by mixing sand and cement in a ratio of 1:1 to 1:6 . It should be used within one hour, in which case the quality of strength is maintained. You can purchase ready-made dry mixtures to perform the work described above.

Mortar

Preparation of lime mortar
The lime mortar is easy to make and can be easily prepared with your own hands. on how the lime is slaked . The lime is poured into the preparation container with water, then we wait until it stops boiling (this goes through the slaking process). Preparing the solution yourself involves several steps:

• Determine the required volume of product; excess is not stored for a long time.
• Sift the lime thoroughly. We take out all the stones, you should get a small fraction. We carry out the work in rubber gloves (corrodes hands).

Attention: the lime must be completely fine. Keep large particles out of mixtures. As it dries, it will begin to “shoot” and this will ruin all the work done.

• Mix the mixture with a trowel or drill with an attachment until it becomes thick sour cream. If the solution is too viscous, add dry mass.
• When plastering stoves, you can add a little gypsum or cement , this will increase the strength of the fastening. The mixture used for plastering the stove is the same.
• should be stirred during operation , otherwise they will quickly harden.

Dry mixtures for furnaces are used at all stages of work, from the initial stage to the lining of the furnace.