How to make refractory concrete with your own hands?

The construction of objects of different purposes often requires the use of refractory materials. With their help you can protect people and designs. Refractory concrete acts as one of such materials. Some of its varieties are able to undergo the influence of temperature up to 1000 ° C, while the shape and useful properties are preserved.

Basic properties

Among the main features of such concretes are:

• High refractoriness;
• Increased operational properties;
• strength;
• No need to use an expensive firing process in production.

Today, refractory concrete can be classified by weight. Manufacture or order can be the following types of material described:

• Especially heavy;
• Light;
• Cellular;
• Heavy.

As a result, it is possible to obtain a material that can perform a structural or thermal insulation function, depending on the ingredient composition.

Production features

If you decide to make refractory concrete, then you should become more familiar with its composition. The material is made on the basis of basic components and some additives, among which are:

• Chamotte sand;
• Magnesite;
• Different types of rubble ;
• Aluminous cement.

Among additives it is necessary to allocate still finely ground and mineral substances which give to a material durability. Among such additives:

• pumice;
• Finely ground chromite ore;
• Blast furnace slag.

These components are added in order to increase the density of not only the finished product, but also the dry composition. Sometimes the fillers for production are manufactured in the factory conditions, but in some cases refractory rocks and the battle of calcined refractory bricks can be used. To obtain different grades of concrete, fillers of different fractions are added. If it is a coarse-grained substance, then its elements can have a diameter ranging from 5 to 25 mm. When it comes to the fine fraction, it is equal to the limit of 0.15 and 5 mm. Among these ingredients should be allocated:

• Magnesite brick;
• Fireclay bricks;
• Bout ordinary brick;
• Aluminous slag;
• diabase;
• basalt;
• Blast furnace slag.

The most common among consumers is refractory concrete, which is made using chamotte, because it meets all the requirements of construction. Aluminum phosphate ingredients and liquid glass act as a linking agent. Portland cement, periclase and alumina cements and serve as binding agents. If the liquid glass is added to the ingredients, it allows to increase the performance characteristics. This is especially true if the concrete solution is used to form the plaster layer.

Additional technology recommendations

Refractory concrete, the composition of which is described in the article, may have a certain brand. Each variety assumes the addition of its plasticizer, magnesite powders and ferrochrome slags. If there is a purpose to prepare lightweight concrete, then the expanded materials should be of the following type:

• Vermiculite;
• Expanded clay;
• Perlite.

If you decide to order the production of a mixture from a professional, then the ratio of components they pick up themselves, in accordance with your project. The composition is selected according to the operating temperature and service conditions.

In addition to the composition of the filler type

If you decide to make refractory concrete with your own hands, then you can use different fillers, namely:

• Dinas;
• Corundum;
• Quartz;
• Finished mixtures.

Considering concretes by composition, it is necessary to distinguish marks. For example, ASBG is a refractory dry alum containing mixture that is used in non-ferrous and ferrous metallurgy, as well as in heat and power engineering. High-alumina concrete mixture with refractory characteristics is designated by the abbreviation VGBS and is intended for creation of monolithic lining of steel casting buckets, walls and at bottom installation.

The composition can be operated at temperatures up to 1800 ° C. The reinforcement dry high-alumina mixture is designated by the letters SSBA. It is intended for thermal aggregates, furnaces, as well as reinforcing layer devices. The operating temperature can reach 750 ° C.

Drying of concrete

Drying of refractory concrete can be carried out after completion of the solidification step. This uses air, and the ambient temperature should not be below +10 ° C. Prior to initial heating, concrete should be kept for a day or more in order to achieve a steady state. The drying operation allows to reduce the volume of free water in the concrete, which could cause a chemical reaction between the atmosphere and the surface of the lining.

After curing, the lining is left in moist air without drying. After curing, dry the lining. If this is not possible, the concrete is left in a closed damp environment. It is important to ensure good ventilation or leave the lining in a well-ventilated area. If you have wondered how to make refractory concrete, then you should be familiar with the specifics of its preparation for operation. For example, the drying step may take place using a suitable fan or blower that will supply hot air.

Features of mixing

Before making refractory concrete with your own hands, the composition of the solution must be carefully selected. This was mentioned above. As for the peculiarities of mixing, it is recommended to use a paddle mixer for this . It is preferable for heat-insulating concretes, but for dense solutions it is absolutely necessary, since it allows to mix the material evenly and correctly with the addition of a smaller volume of water. As for the concrete mixer, this effect will be very difficult to achieve.

This recommendation is also relevant for the reason that for dense concrete the moisture content can be critical. Indeed, for the materials described, the maximum strength is required along with the optimal density. By its nature, thermal insulating concretes are softer than dense, so it is important that they are kneaded using the required amount of water. Its surplus can cause a decrease in strength and density, while a drawback will lead to a decrease in fluidity.

Proportions of refractory concrete

The preparation of refractory concrete must be carried out in accordance with certain proportions. If a fireplace is to be built using the material, the solution should be able to withstand a temperature of 1200 ° C after hardening. From the mixture it is possible to make a fireplace and firebox. To carry out the work, one part of M-400 concrete, two parts of sand made of refractory bricks, as many pieces of crumb from a bricks battle, as well as 0.33 parts of a pulverized chamotte additive will be required.

If you plan to build a monolithic hearth, then during it the heating equipment will be constantly exposed to an open flame. To do this, you need to prepare a solution with the following proportions: 2.5 parts of rubble, part of concrete, 0.33 parts of chamotte sand. As for the rubble, it can be made of quartz or red brick, as an alternative solution, sometimes a thin red brick is used.

Conclusion

The characteristics of the preparation of a mortar for the production of refractory concrete are similar to those used when the conventional cement slurry is closed. If it is supposed to fill in the formwork, then the movement should be directed clockwise. Sometimes forms are made from plywood to form products.

In order to avoid the evaporation of water during the solidification process, the molds after manufacture should be compacted. This facilitates easier extraction of castings. The simplest method of sealing is polyethylene, but in order to achieve the best result, you should use silicone, which is pre-lubricated with vegetable fat.