Refractory cement with their own hands. Heat-resistant concrete: types of material according to temperature conditions

heat resistant concrete is concrete, which can long time withstand heating up to a temperature of 1000 ° C, and at the same time do not change the shape and performance properties. Apply it in various fields: industrial construction, housing, as well as in the construction of specialized facilities. Heat-resistant material can be made by hand, the main thing is to follow the instructions and recommendations of experienced builders.

Scope of heat-resistant solution

The actual use of refractory material in the construction of industrial structures, foundations, combustion chambers, as well as in the construction of residential buildings. Heat-resistant concrete is also used in the chemical industry - where they make Construction Materials required in the field of energy. The heat-resistant material is used in the construction of ceilings, floating structures and running bridges. Its use is preferred in those designs where the light weight that a heat resistant material can provide is desired. After all, he is able to reduce the weight of structures by almost half due to being in concrete mix porous filler. Use heat-resistant concrete in the construction chimneys, fireplaces and stoves.

Classification

Refractory concrete is classified according to the following indicators.

By structure:

• easy;
• porous;
• heavy.

By appointment:

• heat-insulating;
• structural.

According to the astringent components included in the composition:

• Portland cement;
• aluminous cement;
• slag Portland cement.

And also - by the nature of the fillers and the operational temperature regime.

Composition and characteristics

A different binder can become a component of the concrete mixture: liquid glass, Portland cement or aluminous cement. Also, in the composition of heat-resistant concrete, finely ground additives are used, which affect volume weight finishing structure. Depending on the binder component, crushed additives and fillers are used in the composition of concrete, the choice of which also depends on the temperature regime, as well as the conditions in which the refractory material is used.

Heat-resistant material, which is made with the inclusion of additives in the form of crushed stone, corundum, etc., is prepared on the basis of basic ingredients. Difficulties in its production do not arise; with minimal construction skills, the refractory composition can be made by hand.

To increase the strength of the heat-resistant material, it is filled with finely ground mineral additives, which increase the density of the product. Aggregates in the constituent heat-resistant concretes can be manufactured at the plant, in addition, refractory rocks are used.

To date, there is the possibility of manufacturing heat-resistant mixtures to order. The advantage of this is the choice of ingredients, as well as their ratio based on the customer's project. The components in concrete are selected according to the expected temperature regime during operation and the service life of the products.

Cooking with your own hands

Heat-resistant concrete can be prepared with your own hands, but then it must perform all the assigned tasks. Also, when working with heat-resistant concrete, you must follow the recommendations and follow the instructions, which, in turn, must comply with the requirements and technological standards. As a result of making a refractory component with your own hands, concrete should be obtained, which, like the factory one, is resistant to temperature extremes and has thermal insulation functions. When heated, it should not lose its properties and shape. Self-preparation of heat-resistant concrete will reduce construction costs.

When making heat-resistant material at home, you need to stock up on liquid glass, barium cement, asbestos. These components will give concrete the characteristics that will allow the material to be used in the construction of structures with a high temperature regime.

To make a heat-resistant material with your own hands, you need to place cement and sand in a concrete mixer in a ratio of one to four. After thorough mixing, water is poured in until the consistency is similar to dough. The resulting solution is poured into molds, and then into the formwork. To remove the air that has appeared, seals are used in the solution.

Materials and tools

To create a heat-resistant solution, apply:

• wheelbarrow;
• mixer for concrete mortar;
• water hose;
• formwork;
• refractory cement;
• Master OK;
• plastic sheet;
• gravel;
• slaked lime;
• spray;
• sand.

Found it, kept it.

cement mortar, heat-resistant concrete mixtures
Cement mortar is the most durable, it hardens in air and in water. Prepared from cement, sand and water. It is used for laying foundations in damp places or on soils saturated with water, as well as pipes above the roof. The cement mortar sets quickly (the beginning of setting is 45 minutes, the end is no later than 12 hours). It is applied no later than an hour from the moment of preparation, with more long terms reduces its strength. The brand, or compressive strength of the solution, is different and depends on the number of constituent materials, as well as the brand of cement. Solution compositions - from 1:1 to 1:6.

To prepare the solution, cement and sand are sieved through a sieve with 3x3 mm holes, measuring them in volumetric doses. The right amount sand is poured thin layer and sprinkled with cement on top, mixed until completely homogeneous, and sometimes additionally sifted through a sieve. Water is poured into the dry mixture to the desired density.

A complex solution is prepared from two binders and one aggregate: cement, lime paste and sand. It is used for laying foundations in wet ground and pipes above the roof. For one part of cement, take from one to three parts of lime paste and from six to fifteen parts of sand.

The solution is prepared in two ways. A dry mixture is prepared from cement and sand, then the lime dough is diluted with water to the density of sour cream. These materials are pre-measured in precise volumetric doses. The prepared portion is added to the diluted lime dough cement mixture, mix everything thoroughly. To obtain a solution of the desired density, water is added and mixed again.

Another way: a solution is prepared from a measured amount of sand and lime paste, a portion of cement is poured into it and everything is thoroughly mixed. Cement can be pre-mixed with water to a creamy state. Such a solution is more plastic than cement, but it is lower in strength. It must be stored in such quantity that it can be used within an hour from the moment of preparation.

Heat-resistant concrete mixtures are used for the manufacture of monolithic open fires or blocks for laying stoves and fireboxes. Cooking technology - as well as cement-sand mortar. The use of concrete, as a rule, requires the construction of formwork and keeping it up to 28 days in a wet mode. Freshly laid concrete (in formwork) is covered with matting or shavings and moistened with plenty of water, especially during the first three to five days. Good results gives the use of polyethylene film for this purpose (steam effect).

Compositions of heat-resistant (fire-resistant) concretes in bulk parts:

For open flames
Cement brand not lower than 400.1
Red brick rubble...2-2.5
Quartz sand or finely ground red brick ... 2-2.5
Finely ground (pulverized) fireclay sand..0.33

For fireboxes
Cement brand not lower than 400.1
Rubble from fireclay bricks.2
Sand.2
Finely ground (pulverized) fireclay sand.0.33

In the last recipe, I am personally alarmed by the "sand", it has a coefficient thermal expansion very different from cement, perhaps "fireclay sand" was meant.

For the construction of stoves, fireplaces and chimneys, heat-resistant concrete is used. This type concrete is used both in residential construction and in industrial. In order for the material to perform its function at the proper level, to guarantee safety and protection, strict compliance with all technological requirements in its manufacture is necessary. The material can be cellular, light or dense. This factor depends on the scope of its application and purpose. Such concrete can perform the functions of reliable thermal insulation.

For the preparation of refractory concrete, liquid glass, asbestos, barium or alumina cement should be added to the composition.

Working with refractory concrete is similar to working with conventional concrete material which reduces the cost of construction works. you can successfully make this material with your own hands. It is resistant to temperature changes and does not lose its properties when heated, and is also the best option for the construction of specialized facilities of various kinds.

The choice of heat-resistant concrete

To make refractory concrete with your own hands, you will have to add liquid glass, asbestos, barium or alumina cement to the composition.

Characteristics of refractory concrete.

These additives make concrete suitable for use in places with elevated temperatures. Ordinary material includes elements that undergo a process of dehydration and dehydration during the heating process. The structure is destroyed very quickly, passing through such a test, and the recovery process is not possible. To avoid such situations, heat-resistant concrete is used. Examining the heat-resistant concrete mixture in detail, it is possible to identify a high content of various impurities. Each of them performs its role, increases strength, binding materials at elevated temperatures. For the manufacture of heat-resistant concrete with your own hands, it is necessary to have binder components in the basis of the material.

For these purposes, you can use:

• slag Portland cement;
• Portland cement;
• high alumina cement;
• aluminous cement;
• periclase cement;
• liquid glass.

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Selection of composition for heat-resistant concrete

Various finely ground impurities are usually added to Portland cement and liquid glass. Heat-resistant concrete can be ordinary or lightweight, depending on the volumetric weight. A material is considered to be light if its bulk density (in the dried state) does not exceed 1500 kg/m³.

Magnesium sulphate (aqueous solution) is used to mix heat-resistant concrete mixture on periclase cement. In order for the hardening of heat-resistant concrete with an admixture liquid glass, it is necessary to introduce sodium silicofluoride, blast-furnace granulated slag or nepheline sludge into the mixture. These additives are introduced into concrete at normal temperature.

Finely ground additives can be finely ground or dust materials, such as the:

• battle of magnesite bricks;
• battle of fireclay bricks;
• lump fireclay;
• pumice;
• chickweed;
• chromite ore;
• fly ash;
• andesite;
• loess loam;
• granulated blast-furnace slag.

For heat-resistant light mixtures, suitable:

• battle of diatomaceous bricks;
• battle of fireclay bricks;
• chickweed;
• fly ash;
• expanded clay.

Small (0.15-5 mm) and large (5-25 mm) aggregates can be crushed materials, such as: breakage of magnesite and magnesite-chromite bricks, breakage of high-alumina and fireclay bricks, breakage of clay, semi-acidic or talc bricks, titanium-alumina and blast-furnace waste slag.

Dunite, balsat, diabase, andesite, Artik tuff, and lumpy chamotte can also be counted among them. For lightweight and refractory concretes, it is better to use vermiculite, expanded clay or expanded perlite as additives. View binder, temperature and service conditions of concrete determine the choice of finely ground additives and aggregates. The use of refractory concrete reduces the cost of work, labor costs, and reduces construction time.

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Do-it-yourself step-by-step preparation of heat-resistant concrete

For this process you need to have tools and materials:

• concrete mixer;
• wheelbarrow;
• Master OK;
• shovel;
• spray;
• hose or other water supply;
• formwork;
• plastic sheet;
• sand;
• refractory cement;
• gravel;
• hydrated lime.

A concrete mixer or a wheelbarrow should be located in close proximity to the source of water supply. Water will be needed for adding to the composition, washing tools and the site. Materials must be mixed in proportions of 3:2:2:0.5, for example - 3 parts of gravel to 2 parts of sand and 2 parts of refractory cement to 0.5 parts of slaked lime. The value of the volumes of the heat-resistant composition should not affect these parameters and the ratio of materials, they should remain unchanged. Gravel and sand are placed in a concrete mixer, refractory cement and slaked lime are added, all ingredients are thoroughly mixed with a shovel so that the components are evenly distributed. Then water is added to the mixture and mixed again. Water is added until the mixture reaches the required consistency (working density). To check from the resulting mixture, try to make a lump. If there is enough water, then the lump will not fall apart and will not blur in the hands.

Data concrete mortar formwork or a special form is filled. This process is carried out with a shovel, the excess is removed with a spatula, after which the surface is leveled. The hardening process of the material is accompanied by increased moisture loss. Sprinkle the surface periodically with water to prevent cracking. Wet concrete can be coated plastic wrap for a couple of days. After this period, the film must be removed and the concrete allowed to dry. Before removing the formwork, the concrete must dry for at least 2 days. After that, the concrete stands and gains strength within 3 weeks. The surface can be used after this period.

Born in England in 1961, lives in Montreal, Canada. Member of the North American Stove Association. He has been in the furnace business for over 20 years and specializes mainly in the construction of Finnish countercurrent furnaces in various options. Areas of interest: non-standard antique brick cladding, Art Deco design, history of stove making. In filling its website www.pyromasse.ca adheres to the policy of "open sourse".

Translation: 02/12/2011

Refractory concrete for kilns - preparation on site

Selecting a refractory concrete mix suitable for use in kiln laying can be difficult. It has the following requirements: high density, large grains and good resistance to thermal shock. The refractory concrete used here is Mount Savages Heatcrete 24 ESC (24 f. extra strength course). The article describes the shaping, pouring, and demolding of four concrete modules used in the construction of an indirect oven oven. The article outlines in in general terms methods of normal work on the object. The equipment and methods in a workshop setting can of course be much better.

There are 4 molds to fill. Top to bottom, clockwise. Hearth, rear plate, top plate and furnace lintel. The mold for the hearth is dark, as it is made from plywood used for molding. Once the molds are assembled, they must be sealed to prevent water from evaporating during the reaction and to allow the castings to be removed easily. Forms can be coated with polyethylene, or treated with vegetable fat and silicone. Both methods are suitable, a method using vegetable fat is described here. The polyethylene gives the finished modules a shiny surface, a type of finish that is easy to clean. Such sheen, however, can significantly hinder the removal of mechanically-bound water during heating. The surface of modules from molds treated with fat is much more porous.

Before pouring refractory concrete, all molds are compacted. Silicone is applied to all joints. The surfaces of the molds are carefully smeared with vegetable fat.

A strip of ceramic paper is placed in the base of the discharge bridge mold. It will form a recess where the same strip will be placed when the jumper is installed. The paper should be covered with a strip of polyethylene to stop the mixture from soaking in during mold vibration.

The mixture must be perfectly mixed in a mechanical mixer. A large number of mixtures are almost impossible to mix by hand. Manufacturers recommend a certain amount of water. One and three quarters of a gallon (7.7 liters) of water per 50 lb (22.5 kg) bag of mix seems to be too little. Although after thorough stirring, the mixture vibrates well into place. Even a small excess of water can significantly damage finished modules.

The water used must be clean. Both the water and dry mix should be relatively warm during mixing, and kept warm before and during the reaction and after pouring. 15-20 C is optimal. If you have to pour at a low temperature and heat the materials, then it is important not to overheat, otherwise the mixture will begin to set before it is laid.

Because the mixture is so tough, it's important to work quickly. Refractory concrete is placed in a mold. It is better to fill out the form with an excess and remove the excess than to underfill and add later. The concrete must be placed into the mold with a trowel before being vibrated. The image shows refractory concrete after vibrating for one minute. Although up to this point the mixture seemed too dry, it filled the molds perfectly after a single vibrating.

Vibration laying of refractory concrete with a perforator. Video, 11 sec.

Vibrolaying, removal air bubbles. Video, 12 sec.

The molds are nailed to a sheet of plywood that rests on top of another sheet of plywood. This makes vibrating more efficient, especially when working on concrete floor. Vibration is produced by a chipper or puncher. By placing a drill bit in the wooden part of the mold, the mold is vibrated, causing the concrete to set and the trapped air bubbles to float to the surface.

These three refractory concrete molds are designed so that the middle and two inner surfaces of the outer parts cannot be easily vibrated, and Special attention should be given to vibrating precisely these parts.

Vibration sets the refractory concrete and removes air, but it also causes the coarse fraction to settle towards the base of the mold, pushing the finer fraction upwards. Since this leads to a non-uniform composition, the mold should not be vibrated longer than necessary.

The external surfaces of the modules facing the fire must be left rough and not rubbed with a trowel. After pouring, the molds should be tightly covered with plastic, and all air removed from under it by smoothing by hand. It is good to shoot the plastic to the forms with a stapler so that the corners are not lifted by insidious night winds.

Forms lined with polyethylene.

Same molds filled with concrete and covered with polyethylene.

Endurance greatly affects strength finished product. Working space should be warm when aging. The exothermic hydraulic setting reaction of refractory concrete will begin several hours after pouring, depending on the amount of water and the temperature of the materials. The reaction will make the product quite hot as it goes on for several hours. It is important that the product be carefully covered to prevent loss of water through evaporation during the reaction. Although I take out and use the modules a day after pouring, once they have cooled it is best to leave them in their molds for an additional two days. If they are taken out every other day, it is best to keep them moist for a few days.

The jumper floats during exothermic reaction. Video, 18 sec.

When making molds for refractory concrete, it is necessary to work precisely. Module surfaces sealed with 1/8 inch (3 mm) ceramic paper must be straight and square to be normal.

Inner surface the hearth of the oven oven was cast in lightly greased wooden form. It is probably preferable to mold it in polyethylene as this will provide a smoother surface that is less water permeable and easier to clean.

The need for the use of refractory materials often arises in the construction of facilities. In the future, this allows you to protect structures and people from the unpleasant consequences of accidental fires. One of these materials is heat-resistant concrete, which is able to withstand the effects of high temperatures up to 1000 oC. At the same time, it retains useful qualities and does not lose its shape.

Classification

There are several types of heat-resistant concrete, which is also called refractory or heat-resistant. The composition of the material includes special refractory additives. The main binder component in the production of heat-resistant concrete is Portland cement. As fillers here can be used: blast-furnace slags, screenings rocks(diabase, andesite, porous rocks of volcanic origin, diorite, artificial fillers), blast-furnace slags.

Divide the material into separate classes according to:

1. Structure (heavy, light, porous).
2. Purpose (heat-insulating, structural).
3. The nature of the fillers.
4. used binder components.

Specifications

Prepared using Portland cement as binding base refractory concrete has a classic strength index. When conducting a compression test, the limiting values ​​are in the range from 200 to 600 MPa/cm2.

Manifestations of thermal stability are observed when temperatures reach no more than 500 °C. Prolonged exposure of the material to an open flame or prolonged contact with hot surfaces significantly reduces the strength properties of cement and often causes defects.

The most refractory concretes prepared on the basis of alumina are able to withstand any household temperatures. Composition-saturated alumina coatings are characterized by thermal stability of the order of 1600 °C and higher. A gradual increase in temperature leads in this case to an increase in heat resistance, since the cement mass is transformed into a ceramic state.

However, despite the high resistance to elevated temperatures, alumina refractory concrete has a relatively low strength. The material made using such components can withstand mechanical pressures up to 25-35 MPa/cm2.

First of all, refractory material is used in the manufacture of thermal structures, furnaces for industrial and domestic purposes, foundations, collectors, combustion chambers. However, it cannot be said that such concrete is used only in structures that are amenable to thermal effects.

Thus, the specific composition of refractory concrete contributes to its widespread use in the chemical industry, in the production of building materials, to meet the needs of the energy sector.

Heat-resistant material is used in the construction of ceilings, floating structures, running bridges. This building basis is preferred due to the need to facilitate structures, taking into account high performance strength and reliability. The refractory composition makes it possible to reduce the weight of structures by about 40%. This is explained by the use of a significant volume of porous fillers in the mixture.

Preparation of the composition

How to create refractory concrete, resorting to making a mixture with your own hands? For this, water, binders and various heat-resistant fillers are used. The manufacturing process has distinctive features. The components used must be of particular purity. In addition, clogging of refractory and refractory components with sand, limestone or granite is excluded.

The assumption of such mistakes in production technology often leads to the rapid destruction of the material.

Manufacturing techniques

There are several ways to produce heat-resistant concrete with your own hands. First of all, you can get the material using a ready-made dry mix, which has all the necessary components. More difficult option involves independent mixing of the components in the required proportions.

The best solution is to use the first method, since the best components are used in the production of heat-resistant mixtures in the factory. In addition, in this case, the manufacturing technology is carefully observed. As a result, the consumer gets the opportunity to use a ready-to-use mixture top quality. Just add solvent or water.

At self-manufacturing to acquire refractory properties of the material, it is advisable to add the following finely ground components to the mixture: andesite, fireclay, chromite ore, magnesite cement. result correct selection ingredients and proportions becomes a material that can withstand elevated temperatures without collapsing.

Tools and materials

By resorting to your own, you can significantly save money by refusing the services of masters. However, before proceeding with the manufacture of the mixture, it is recommended to prepare necessary tools and materials. This will require the following:

• equipment for mixing concrete components;
• spatula-trowel;
• wheelbarrow for transporting materials;
• shovel;
• sprayer for water;
• wooden formwork, casting molds;
• sand, gravel, slaked lime, heat-resistant components;
• Portland cement.

Manufacturing features

In the manufacture of refractory cement, pre-prepared dry components are placed in a concrete mixer (the cement-sand ratio is 1:4). After the formation of a homogeneous mixture, water is added in the amount necessary to achieve a pasty consistency. Since refractory building substrates have specific viscosity characteristics and quickly harden when water is added, it is best to follow the recommendations of the cement manufacturer.

The finished mixture is distributed into molds, poured into the formwork or used as binder material when laying refractory brick. Using aluminous fillers, after adding water, they act extremely quickly, which makes it possible to avoid premature setting of the solution.

If it is necessary to prepare small volumes of mortar using Portland cement, the components can be mixed manually. It is convenient to use wide containers for this - deep basins, bathtubs, troughs.