Refractory mixture for laying furnaces

Masonry mortars for individual furnace designs

The general requirements for the solution are:

• heat resistance - ensures the safety and functionality of the furnace;
• elasticity - is a condition for good crack resistance of the furnace walls.

According to the type of binders, all furnace mixtures are divided into:

• cement;
• plaster;
• calcareous;
• mixed (if they contain more than one binder).

Furnace foundation. For its device, lime or cement-lime mortars are used. With excessive moisture in the base under the foundation, a cement mortar should be preferred, it is not afraid of moisture.

Chimney. For the part that protrudes above the roof, lime or lime-gypsum mortar is taken. If it is necessary to accelerate the setting of the solution, then gypsum is added to it. If the priority is the strength of the masonry, then cement is added.

Furnace body. Here you can not do without clay. The mortar consists of clay, sand and water. The quality of the solution is greatly affected by the fat content of the clay.

Mixing and quality control

First, clay is poured into the trough. It should be filled with water in a small volume. The clay is left for a period of six hours to two days to get wet. During this time, it is stirred. For example, you can put on rubber shoes and trample clay. Water should be taken 1/4 of the available volume of raw materials. Next, sifted sand is added. The whole mixture is stirred with a shovel. You can check the consistency by the behavior of the mass. If the solution slides slowly from the shovel, then mixing can be completed. To determine plasticity, a small flagellum 20 cm long and 1.5 cm thick should be molded. It should be connected around a five-centimeter wooden blank. The flagellum should stretch evenly. If it is torn, then the ends should be sharp. If there are no cracks on the fold, then the solution is too greasy. Accordingly, in the presence of numerous gaps, the mass is “skinny”. In the second case, clay should be added, and in the first, sand. As a result, it is necessary to get several small cracks on the fold.

The main options for mixtures for laying a fireplace

It must be understood that the construction process involves three main stages:

• foundation preparation:
• masonry of the main array;
• exterior finish.

The corresponding stage will need a different mixture, although universal options can be used.

To fill the foundation, you need a concrete mortar: three parts of sand are taken for one part of cement and diluted with water to a state similar to wet earth. You can add fine gravel.

Such a solution is not sold ready-made, it must be prepared immediately before pouring the base. The setting of the solution will begin in half an hour, and the final hardening after a day. Next, you can proceed directly to the laying of brick or stone.

This process requires a refractory masonry mixture, which in its composition will contain fireclay - a special type of heat-resistant clay. You can buy it ready-made and dilute it with water to the desired consistency, you can make it yourself, which will save money, but will require more time and responsibility.

The preparation of mortar for plastering can be carried out using lime. This option is quite widespread. Components:

• lime;
• water;
• plaster or cement.

Lime must be carefully sieved so that there are no stones and large seals, since such inclusions will not be able to completely dissolve, and “shoot” when dried, which will negatively affect the final result.

Cement or gypsum is added to make the plaster more durable, but you can do without them.First, mix the dry ingredients, then add water in small portions. Lime will begin to be extinguished by dissolving.

The consistency should be like thick sour cream, if a liquid solution is obtained, a dry component should be added. In the process of cooking, it is necessary to mix the ingredients thoroughly so that the hardening process does not begin. When ready, you can start plastering.

Rules for the preparation and application of ready-made mixtures

The advantage of purchased formulations is the ease of mixing the solution. To be able to prepare it, you will need a container of the appropriate volume and, without fail, a mixer or an electric drill with a nozzle. The fact is that the manual preparation of the solution is associated with the application of certain physical efforts, and to facilitate work, more water is often added to it than it should be. As a result, there is a loss in the quality of the finished mixture.

The preparation of the solution is reduced to pouring the dry mixture into warm water and stirring the mass until the lumps are completely dissolved. It should be similar in consistency to thick sour cream. The solution is left for an hour exposure, after which it is thoroughly kneaded again.

Dry mixes for laying fireplaces and stoves have a water-holding capacity, so the bricks do not need to be pre-wetted. Firstly, it saves time, and secondly, it significantly reduces the period required to dry the masonry. The good elasticity of the solution, obtained due to plasticizing additives, is reflected in the possibility of making thin seams (2-4 mm) and, as a result:

• on the economical use of bulk material;
• on the attractive appearance of stove and fireplace walls;
• in the absence of cracks, often appearing in a thick masonry layer.

Heat-resistant compositions should be worked at an ambient temperature not lower than +10 and not higher than +35 degrees. The solution can be applied with a layer of 10-12 mm. It is interesting that the seams of fireclay clay mixture during the operation of the furnace acquire additional strength under the influence of heat.

Preparation of the composition for laying fireclay bricks

Refractory masonry mixture prepared on the basis of fireclay tolerates fairly high temperatures. Here you can use coal without any problems when burning, without worrying about masonry. The preparation should be taken most carefully and responsibly, since if the components are calculated incorrectly or the manufacturing sequence is violated, an inappropriate mixture for styling may turn out.

• We put fireclay clay in a bucket and fill it with water so that it is not visible and leave to infuse for about 12-72 hours. From time to time you will need to stir the soaked mixture.
• Then this clay will need to be rubbed through a sieve. It is best when the cell does not exceed 3x3 mm. Using the same sieve, it is necessary to skip the sand and add to the clay. The best ratio for masonry is considered by many experts: 2 parts sand to 1 part clay. The dry composition of clay and sand must be mixed until smooth, and after that add water.

Attention: In order for the masonry composition to come out the best, it must be constantly stirred when adding water. In this case, water should be added continuously, but in a small stream

When the mixture becomes creamy, stop adding water. It is at this step that it is best to pour salt into the solution.

• An ordinary bucket of the mixture requires about 150 grams of salt. Salt gives the solution a better strength. Then add about half a trowel of cement - it will strengthen the composition. In some cases, mixing with liquid glass occurs.
• A properly made solution will flow down the shovel in an even layer, the wrong one will spread heavily or even become a lump.Such a mixture is the best choice for filling voids.
• The approximate amount of mortar for laying one hundred bricks is two buckets. In the case of laying out a Russian stove, the amount must be increased by about twenty percent due to the specifics of the masonry.

A refractory mixture is used for the fireplace and stove. By the way, the smaller the fraction of the components, the better the composition will be.

Refractory putties

In addition to traditional refractory solutions, putty materials are also used in finishing work. They are used for lining heated surfaces. Almost all materials for such work have a similar composition, only the proportions of the components differ. Clay and lime are the basis everywhere.

Most often, refractory putties are used to finish the stove for further finishing. Mass has the following advantages:

• Safety. The composition of the substance is environmentally friendly. When heated, no components harmful to humans are released from the putty.
• Fire resistance. Even with strong heating, the formation of cracks on the surface of the putty layer is unlikely.
• The service life of the coating (with proper application) is more than 40 years.
• High degree of adhesion with other building materials and coatings.

When finishing the furnace, it is important to follow the correct sequence of applying materials. Otherwise, the finish of the product may crack.

Mortar options for laying stoves

Today, various modifications of masonry mortars are used, among them the following are popular:

• heat-resistant mixture, which is intended for outdoor use. Such solutions are used when laying, plastering barbecues, barbecues, smokehouses, stoves, operated only in the open air;
• mortar for laying household, industrial furnaces, fireplaces from fireclay refractory bricks. The operating temperature of such structures can be up to 1750 degrees;
• a special masonry mixture designed to work with red brick. With the help of such a solution, fireplaces are laid. household stoves, stoves, heaters, the operating temperature for which is up to 850 degrees;
• for fastening tiles, plastering the surface of fireplaces, chimneys and stoves, a special masonry mixture is used.

The masonry mortar has such characteristics as:

In a lean solution, you need to add lime dough, in a greasy one - sand.

• the appearance must be uniform, free of impurities;
• composition humidity - no more than half a percent;
• maximum grain size - up to 2.5 mm;
• bulk density - 1500 kg per cubic meter;
• ready-made masonry mortar can be used within three hours;
• water-retaining capacity of the resulting solution - 95 percent;
• compressive strength - two Mega Pascals;
• weight loss of the mixture during calcination - up to 5 percent.

The special composition, which is used for pouring, repairing the hearth inside the furnace, has the following characteristics:

• the minimum temperature for work is five degrees Celsius;
• the time of using the ready-made solution is one hour;
• maximum grain size - 5 mm;
• water consumption for the preparation of 25 kg of the mixture - 2.5-3.5 liters, the finished mass - 11-12 liters per 25 kg;
• heat resistance - 1300 degrees.

Factory masonry mixtures for laying stoves

We are talking about refractory dry powders, which, after dissolving in water, turn into a homogeneous mass. The recipe for cooking is usually indicated in the accompanying instructions. Along with the usual components (sand and cement), the solution contains special heat-resistant additives.

The refractory mixture for laying furnaces, manufactured at the enterprise, has a number of advantages:

• Well crafted composition. Under production conditions, a careful dosage of each component is carried out, according to time-tested recipes and proportions.
• specific additives.Components that give refractory mixtures their "proprietary" characteristics are often not commercially available (and sometimes even kept secret).
• Versatility. As a rule, industrial mortars are multifunctional: they can be used to lay stoves, and then plaster finished walls.
• external aesthetics. Although a finish is still applied over masonry or plaster, it is much more pleasant to work with an attractive-looking solution.

Our stove-makers especially liked the products of such manufacturers of masonry mixtures for stoves and fireplaces: PLITONITO, TERRAKOT, Makarov's Furnace House, Pechnik, Scanex, SPO. As for the disadvantages of this variety of materials, their high cost is usually called. In cases where it is necessary to save finances, they try to use self-prepared heat-resistant solutions.

Working with mix and fireclay bricks

Refractory mixtures for laying furnaces must be made with high quality

But it is equally important to do their proper styling.

It is especially necessary to pay attention when filling the seams with a solution. With poor-quality filling, water may enter the seams, and if it freezes, the masonry will crumble much earlier than planned

The choice of brick laying category depends directly on the future temperature state. The higher the temperature, the smaller the seam should be:

• 1 mm - the first category;
• 2 mm - the second category;
• 3 mm - the third category;
• more than 3 mm - the fourth category.

To determine the quality of the seam, I use a special probe 15 mm wide, and the thickness must be equal to the seam.

• The probe must penetrate into the seam by 20 mm. To ensure that the bricks are positioned correctly, they are tapped with a trowel handle. In order for the seams to be a certain horizontality, ordering rails are used and a cord is attached to them. After the first layer, laying is determined only by this cord.
• The characteristics and reliability of masonry largely depend on the uniformity of application to the surface of the solution.

Caution: The brick sucks moisture out of the mix, preventing it from drying out. Therefore, during the laying process, the brick is periodically moistened or even pre-soaked

The refractory mixture will help you make a quality structure, but you should never rush. You should look at the photos and videos, understand the whole cooking process. After all, construction requires quality materials.

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mixtures were sour

One of the most popular kiln mixes is mortar. It comes in the form of a very fine powder. For application, the powder is diluted with water and used for masonry in tandem with refractory bricks or stone.

Not every mixture of mortar is suitable for laying the hearth. There are refractory and conventional hardening mixtures. The latter become hard during heat treatment, like ceramics. They contain hydraulic cement.

Mixtures without hydraulic inclusions with other additives are called refractory. There are different types of mortar, differing in grain size. So fine-grained mixtures are called with particles up to 1 mm, and large - up to 2.

Different markings of the solution are denoted by the letter abbreviations МШ. The material is most often used for domestic or household stoves, for the luggage of industrial hearths, a mixture of alax is used. The finished shell from the mortar mixture has a very high strength and has been used without problems for many years.

Features of the preparation of working solutions

Regardless of the composition of the refractory mixture chosen, the master will need water in any case. It should not contain a large amount of hardness salts - calcium and magnesium bicarbonates.

Usually, the population knows the characteristics of local water, the location of sources with water of low hardness.If necessary, you can slightly soften the water using special methods, but it is advisable to do this only as a last resort, since the pleasure will be expensive.

For do-it-yourself masonry of all parts of the furnace, white sand, which has a quartz composition, is ideal. Yellowish sand grains can be used for laying any parts of the furnace structure, except for the furnace.

There are long historical methods for determining the amount of sand to add to clay. The ancestors lived a leisurely, measured life, so the mixtures were tested for more than 3 weeks. Now people make the check faster - they prepare several options for cakes or balls, wait for it to dry completely, then drop it onto a wooden surface from a height of one meter. Worthy of attention is the composition that did not split. If there are several such resistant samples, the height for testing can be increased, and in the end, the most durable option should be chosen.

The final control check can be carried out as follows: grease the wide part of the brick (bed) with a mortar layer of at least 3 mm with the finished mixture, lay the second brick on top, press it well by tapping it with a wooden handle, wait 10 minutes and lift it up. If the bottom brick is held and does not fall, the composition is suitable.

lime mixture

It contains lime paste and sand. Lime dough can be prepared independently by mixing quicklime and water in a ratio of 1:3. But it is better to buy ready-made dough in the store, its quality is much higher.

To prepare the mixture, fine sand sifted through a sieve is mixed with lime dough in a ratio of 3: 1 and diluted with water until a creamy consistency is reached. After preparing the mixture, its plasticity must be checked. This is done by stirring the mixture with a wooden plank:

• lean mixture - does not stick to the bar at all, lime must be added to it;
• normal - after removing the bar from the solution, it remains on it in the form of a film or lumps;
• oily - sticks to the wood in a thick layer, you need to add sand.

The disadvantages of the lime mixture are the long drying time of the masonry and the negative impact on the respiratory system.

Heat-resistant mixture for laying stoves

To give greater strength, concrete is also added to the material. According to its operational properties, such a solution will not be inferior to lime. The hardening of the concrete mass begins after 45 minutes. Before mixing the components, they are passed through a sieve. Then sand is poured into the prepared container, and cement is placed on top of it. This mass is stirred until a homogeneous composition is obtained. Then water is added. When mixing, it is necessary to achieve a viscous consistency. The solution should not be too thin or thick. For the construction of a monolithic furnace, components are used in the following ratio:

• 1 part of Portland cement (M400);
• sand - 2 parts;
• brick rubble - 2 parts;
• fireclay sand - 0.3 parts.