7 tips on how to properly prepare mortar for laying brick kilns


  1. №1. Elements of the furnace and type of solution
  2. №2. Masonry solutions: types and characteristics
  3. No. 3. Clay mortar for oven
  • Clay quality control
  • Sand selection
  • Preparation of water
  • How much sand and water to use?
  • Preparation of a clay solution for a furnace
  • №4. Clay-chamotte mortar
  • №5. Lime mortar for the furnace
  • №6. Cement-lime mortar
  • №7. Ready-mixed stove mixes
  • Finally
  • .

    Oven heating enjoys unremitting popularity. First, there are still a lot of non-gasified territories and there is simply nowhere to go, and secondly, heating furnace is much cheaper, and thirdly, furnace heating is ecologically more than twice as high centralized. To build an oven that will last several decades, it is necessary to take into account a lot of nuances, butThe greatest difficulties often arise with masonry mortar. It is not so easy to prepare mortar for laying brick kiln, as is the usual cement-sand composition, which is used everywhere for small repair works. The conditions of the furnace functioning are complex: temperatures from -30 to +10000C affect its different parts, and this is not counting wind loads, so the usual cement slurry, alas, can not cope.

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    For different elements of the furnace different compositions are used, and the final result depends not only on the preparation process, but also on the quality of raw materials, and all this is important to take into account.

    №1. Elements of the furnace and type of solution

    The furnace is a responsible design, the strength and durability of which depends not only on the brick chosen for it, but also on the solution with which these very bricks are fastened. At the same time, a number of negative factors are acting on the furnace, and since there is only one masonry solution, which would cope with both frost, and with high temperatures, and with icing, not exist,have to use different compositions:

    • for the foundation, which takes on the main load, but does not experience special thermal effects, you can usecement-limeor lime solution;
    • for heat storage partThe furnace, which is affected by temperatures of up to 6000C and flue gases, is best suitedclay solution;
    • forfurnace section, where the temperatures are maximal, and the chemical effect is not strong, one can takeclay or clay-chamotte mortar;
    • for the source of the chimney, which is affected by temperatures up to 4000 ° C,clay solution, and for friable -lime;
    • for chimneys, where the temperature is low, but there are wind loads,limesolution, some even allow ordinary cement.

      1 - foundation, 2 - furnace, 3 - smoke, - cladding, 5 - chimney

    №2. Masonry solutions: types and characteristics

    For masonry of the furnace from bricks, such solutions can be used (the first three more often, the others less often):

    • clay- the cheapest (all components can be found free of charge), but at the same time, its preparation is the most time consuming. Its strength is average, but the heat resistance is a record -up to 11000С, which allows it to be used in furnaces. The solution possesseshigh gas densityi.e. the ability to trap flue gases. Althoughit is difficult to prepare a solution, working with it is easy enough, because it is suitable for unlimited time. If it is dry, you need to moisten a little to restore the properties;
    • mortarwill cost more than clay, in cooking is more simple. Strength is higher than that of clay, it standstemperatures up to 5000С, has an average gas density, "does not breathe can be used for outdoor works;
    • cement-limeLead over lime in strength, but inferior in terms of heat resistance and withstands only2500C, gas density is low;
    • clay-chamotterepeats the properties of clay, but has a higher thermal resistance, which is13000С. It is more expensive than clay, as chamotte sand will have to be bought, but it is not cheap;
    • cement-chamotteon properties it approaches to clay, but it is expensive, and it is necessary to work with it quickly - after 40-50 minutes after kneading it becomes unusable. This solution has high gas and heat resistance, and strength is almost like that of cement-lime.

    When furnishing furnaces, gypsum-lime mortar is also used, but it goes exclusively to facing works.


    No. 3. Clay mortar for oven

    A set of components for clay mortar to ugliness is simple:clay, sand and water. The complexity lies in theselection of suitable raw materials and optimal ratio of components, which depends on their quality, so many decide not to bother and buy the finished mixture (see below). The stoves perform a masonry seam 3-4 mm thick, but if the joints are made thicker, the clay may begin to crack, in air is absorbed by the cracks, which reduces the thrust and increases fuel consumption, and also increases the risk of carbon monoxide room. On 100 bricks on the average it is required about 3 buckets of a clay solution. The most interesting in this composition is the ability to disassemble the clutch without damaging the building material.

    The main parameter of the clay solution is the fat content:

    • fatty solutionshave a high plasticity, but can dry when dried;
    • lean solutionsThey are not plastic and crumble when dried;
    • normal solutionsgive a small shrinkage, have sufficient plasticity, after drying, almost do not form cracks.

    Exactproportions of clay, sand and waterfor the preparation of a quality solution can not be named - it all depends on the characteristics of the components. Sand to clay is usually added from, to 5 parts, the most common ratio is: and:. Water adds about 1/4 of the volume of clay. There are waysmake the clay solution more durableadding to it table salt (150 g per 10 kg of clay) or cement (1 kg per 10 kg of clay), but if correctly pick up the raw material for the solution and mix it in the required proportions, then such additives do not will be needed.

    Clay quality control


    The quality of clay experienced professionals are able to determine by touch, and everyone else will have to work hard and do several experiments. Prepare clay mortar for the furnace can be with minimal financial investment - only labor and time will be needed.

    Clay refers to common minerals, and it will take a little time to find its way out on or near the site. For stove laying, onlymedium-heavy clay, the fat content is determined by the ratio of alumina and silicon oxides: the larger the first, the fatter it is.Check the fat content is simple:

    • the first wayassumes to take a little clay and, moistening it, to make a ball with a diameter of 4-5 cm. It is put between two boards and squeezed, watching when cracks begin to appear. If the clay is thin, then the ball will already fall into pieces with insignificant pressure or the cracks will go on squeezing it by 1/5. If the clay is oily, the ball will give cracks when compressed by 1/2. We need a normal clay, the cracks on which are compressed by 1/3;

      a - lean clay, b - normal, in-fat

    • second wayassumes the formation of flagella 15-20 cm in length and 4-5 cm in thickness, stretching them and bending around a rolling pin or a shovel shank.Oily claystretches smoothly, and the ends at the point of rupture will be sharp, when bending it around the rolling pin there will be no cracks at all.Skinny claybreaks abruptly, gives an uneven rupture, and when bending - numerous cracks.Normal claystretches smoothly, breaks off when the connection becomes too thin (1/5 of the diameter of the bundle), and when folded it forms small cracks;

      a - fatty clay, b - normal, in - skinny

    • the third wayIt is proposed to form a ball of steep dough 4-5 cm in diameter and cakes with a diameter of 10 cm. When the samples dry 2-3 days later, they are examined for cracks.Oily claywill be covered with cracks, and when falling from a height of 1 m the ball will not break. Skinny clay will not crack, but the ball will break when hit against the floor.Normal claydoes not crack and does not crumble;
    • the fourth waywill require 2-3 kg of clay to be poured with large amounts of water. After the lumps are broken, the slurry is mixed with a jug. Normal clay leaves separate clots on it, lean - covers a thin layer, and fatty - strongly adheres and completely envelops the paddle.

    Adjust the fat content of claycan be done by adding sand (for fatty clay) or more fatty clays (for skinny). How much water and sand to add to the clay solution depends on the characteristics of the clay available. This will be discussed later.

    Sand selection

    Use in the furnace works can be white quartz sand, yellowish from spar also suitable, but only not for laying bricks in the furnace zone. Self-excavating sand is necessary firstsievewith cells, *, mm, so that garbage, root particles, grass, gravel, etc. are eliminated. More difficult get rid of small organic matter, which is necessarily present in the sand, and with time can worsen quality masonry. Clean it with washing - this method is economically viable, if there is an independent source of water supply. Otherwise, it will be cheaper to buy suitable sand, which has already been rid of organic substances by drying or heating.

    For flushingas a container, you can use a pipe cut with a diameter of 15-20 cm and a height of 3 diameters. Sand fill it up by 1/3 and turn on water. Finish the procedure, when within 5-10 minutes the water comes out clear.

    If you decidebuy sand, it is desirable to take several fractions and mix it - so the masonry will be stronger. You can mix the sand of the fraction, mm (1 part) and, 5 5 mm (2 parts).

    Preparation of water

    Water for the solution must besoft and slightly mineralized. Once the stove-makers specially collected rainwater for these purposes, today one can use tap water artesian. Documents located on the well site should be provided with an indication of the approximate hardness of the water. If the salts of magnesium and calcium in water are more than 250 mg / l, then water is not recommended for preparation of the solution, and softening it will require considerable expenses.

    How much sand and water to use?

    Another difficult point is determining the necessary proportions for the future solution.The ratio is determined experimentally:

    • a sample of clay is divided into 5 equal parts, added to each water, a volume of about 1/4 of the volume of clay. After a day, when clay is dehydrated, it is mixed, passed through a sieve with a 3 mm cell and again defended for 24 hours. If after that the turbid water is squeezed out, it must be drained;
    • the first sample is left without sand, in the second one is added 1/5 of the clay, in the second - 1/4, in the third - 1/2, in the fourth - 3/4, in the fifth - 1 part. Sand is added in several steps, thoroughly mixing the samples of solutions;
    • from each solution, two bundles 30-40 cm long and thick, cm, a ball 4-5 cm in diameter and a flat cake with a diameter of 15-17 cm and thickness from the finger, samples are labeled so as not to get confused, and leave to dry 2-3 days;
    • repeat the experiment, as with checking clay for fat content: one bundle is stretched and look at the nature of the rupture, the second - wrapped around a rolling pin or a shovel shank. The normal solution should give a break of 1/5 of the original diameter, and when wrapped on a crust and a little below it appear small cracks. The fatty solution does not crack, the lean solution breaks up into slices and breaks with a large rupture. This experiment gives an ambiguous result, andcan meet several requirements at once, so we reject the exact ones that are not suitable and start throwing pellets and cakes from a height of 1 m. Those that are split, immediately remove from the "competition". If the test passed two solutions, increase the height of the fall. The proportion of sand is the same as in the strongest sample.

    It remains only to find out,how much water to useand clarify the proportion of sand. For this, a trial mix of clay, a selected amount of sand and pure water is made, while water is added to the eye, about a quarter of the volume of clay, and then look at the fluidity of the solution. We make a trough a hollow: if it is torn, then water should be added if it swims - the solution is to stand and squeeze out water with a slurry, and preferably in a measuring container, in order to take away its quantity from added to the solution and output the exact formula. Ideally, the trowel should have a trace with sharp edges, do not crumble and not blur.

    Specify the proportion of sandwill help all the same trowel. It must be soaked in the solution, and if it turned out to be obsolete, then on the trowel there will be a continuous layer of clay - it is necessary to add sand. Skinny solutions were excluded at the previous stage. Ideal is the composition, which leaves on the trowel a thin layer with figured divorces.

    Finally,To make sure that the solution can be accurately used for laying the furnace, we test its strength. We take a brick, we put on it a solution with a thickness of 3 mm, we put the second brick on top, press it, wait 10 minutes and raise it for the upper brick. If it was possible to raise two bricks stuck together, the materials and their proportions are chosen suitable.

    Preparation of a clay solution for a furnace

    The classic and easiest way to prepare clay mortar begins with the fermentation of clay with the necessary amount of water. After its deoxidation (about 1 day), the mixture is pumped through a sieve and the necessary amount of sand is added. Prepare the solution better in a large container, for example, a barrel or tub, mix with a large planed board (merry), deliver raw materials in buckets, and to the masonry the finished solution is worn on a board of boards (firing). Readythe mortar must slip off the trowel or shovel, do not stick to them, but leave a small trace on the surface.

    №4. Clay-chamotte mortar

    Formasonryfurnacesrecommend the use of a clay-chamotte solution, but the stove workers make an amendment andallow the use of a conventional clay solutionfor the construction of furnaces with a not very intense thermal regime: it is a Dutch and Russian stove, cooker, barbecue.


    In other cases, gray, white, or yellowish clay of high fat content is required. It is covered with chamotte sand, but more often for economy use a mixture of quartz and chamotte sand in the ratio:. Water should be used with soft, hardness up to 160 mg / l. Preparation does not differ from ordinary clay solution with one nuance - samples for strength will not be needed, because it is provided by raw materials.

    №5. Lime mortar for the furnace

    Clay mortar does not have sufficient strength for laying foundation, and under the influence of condensate in the zone of the chimney can generally crack, so a limestone solution is used for these parts of the furnace. To prepare it you will need:

    • calcareous dough;
    • sand;
    • water.

    Slaked lime for these works is not suitable - you need to take a quicklime and quench it yourself to get a known test. At home, this process is not recommended: it is difficult and dangerous.Lime dough is better to buy in the building store ready.

    Cooking lime mortar is ten times easier than clay. The required amount of self-excavating sand is sieved through a sieve with a 1 mm cell, the fractions selected are selected, mm. The presence of organic matter in the sand in this case will not be a problem, the more lime has biocidal properties. Water can be taken from ordinary tap water: the requirements for its rigidity are not strict.

    The ratio of dough to sand water is added to the consistency of fatty sour cream. Perhaps you need to adjust this ratio. Lime paste is well kneaded and begin to add sand to it, beginning with 1/2 part. After vymeshivaniya look at sticking with a solution veselka: ideally, it should stick a layer of 2-3 cm, and it is to obtain a similar effect, add sand. Usually, it's about 3 parts, but maybe up to 5.

    Final stage -flow test. On the brick, we apply a solution of 3 mm, from above we put the second brick, tap it and observe the behavior of the solution. Ideally, a bit of solution should appear along the edges, which will not drain. If it is not squeezed out, you need to add a little water, drains - add a calcareous dough, Since the amount of sand necessary to ensure proper plasticity is determined in the previous stage.

    №6. Cement-lime mortar

    Cement-lime mortar is even stronger than lime mortar, and cement will need nothing, and the higher its grade, the less its amount will be used. You need a ratio of cement, dough and sand 10. First, water is added to the calcareous dough, kneaded and cement is introduced, without stopping stirring, then sand is added and the solution is kneaded. The exact amount of sand and water is best determined in a test small batch.

    №7. Ready-mixed stove mixes

    Those who fear that with the selection of clay and proportions can not cope, can choose toready mixes for ovens. They are solddry, and their preparation consists in the addition of water and thorough mixing. Everything is very simple and fast, but experienced stoves still advise to be confused and prepare a clay solution with their own hands.

    Ready-made dry mixes for furnaces are:

    • simple, consist only of clay and sand. This is the most economical and optimal option;
    • improvedwith the addition of plasticizers and lingosulfates, which increase the strength and refractoriness of the solution, increase resistance to sudden changes in temperature and humidity;
    • heat-resistantThe mixture, which includes clay and fireclay filler. Such compositions can withstand up to 13000C and are suitable for laying the furnace part.

    If the mixture is cement, then the purchase is better to refuse.How many ready-mix for masonry100 bricks, it is difficult to say, so the same composition of one manufacturer from batch to batch and even from sack to sack can be very different. As for theproducers, then in the stores are presented the mixes from a number of domestic companies, incl. «Terracotta, Plitonit, Pechnik,Termix, from Borovichevsky, Kostroma and Yaroslavl brick factories.


    Select appropriate components and determine the necessary proportions should be given sufficient time. If you prepare a mortar for bricklaying the furnace incorrectly, then the design will pass the flue gases, have insufficient traction, and even completely crumble and crack.

    Tags:Brick, Stove
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