Wood concrete: description, application, types, advantages, disadvantages, photos, videos.

00:00, 01/11/2021 8 Plot: House in focus

Advantages and disadvantages of wood concrete, GOSTs, secrets of choice

Photo: srbu.ru

Another material, hitherto not mentioned in the “House in Focus” project, that is used to build houses in our country is wood concrete (it is also sometimes called wood concrete). It’s hard to call it a novelty - it was made in the USSR back in the 1960s, and there is even a story that it was used to build a canteen at a Soviet polar station. Whether it was true or not is difficult to verify. However, wood concrete blocks occupy their not the largest, but strong place in the market of materials for private housing construction. We invite you to get to know him better.

What is wood concrete

What is wood concrete? The word arbolite comes from the Latin arbor, “tree” and litos, “stone”. On our territory (i.e. the former Union) it is called wood concrete, and abroad - wood concrete. Wood concrete includes sawdust, and wood concrete only includes wood chips.

Wood concrete is a material consisting of a mixture in which cement is used as a binder base (instead of cement there can be lime, magnesium binder), organic filler (wood chips), and a small amount of chemical additives.

Insulation with foam plastic and penoplex

Builders do not recommend using polystyrene foam when insulating wood concrete walls. Since this thermal insulation material will accumulate moisture in the walls, which will lead to their freezing in the cold season.

In addition, insulating the facade of a house with polystyrene foam will cause the wood concrete to lose its vapor permeability. And the building will have to have additional forced ventilation.

But penoplex can be used when sealing cracks on blind areas. And for the facade of the house it is better to choose vapor-permeable materials.

Positive aspects of the material

One of the most important advantages of wood concrete is its environmental friendliness. This is a building material that is safe for human health. Its composition and production are also absolutely safe, including for the environment. And chemical additives have long been used for the benefit of humanity. For example, an additive such as aluminum sulfate is used for effective water purification at water treatment plants.

The main advantages of wood concrete are: Increased heat and sound insulation, which is achieved due to the porosity of the material, which eliminates the need for additional insulation. Absolute fire resistance - due to the fact that wood chips are surrounded by a thick layer of concrete. Strength. The production technology gives wood concrete high bending strength coefficients. That is, where other material cracks, wood concrete will remain unharmed. Only under heavy loads can this material deform, but also quite slowly, since wood chips have binding functions.

Plasticity is achieved again thanks to the wood filler, so wood concrete is not susceptible to damage during transportation, installation, as well as exposure to natural factors (soil vibrations, temperature changes, etc.) Lightweight compared to conventional materials (brick, concrete), which makes work easier for laying blocks. Durability. Wood concrete does not rot and is slightly affected by fungus, mold and chemicals. It is easy to change the shape of the block using a saw or an ax, and driving in nails and screwing in self-tapping screws even without dowels will not present any difficulties.

Reviews from home owners about wood concrete blocks

Konstantin, 37 years old, St. Petersburg: “The house doesn’t warm up. As the operation of the building has shown, it is impossible to do without additional insulation. The first reason for low frost resistance is the use of a structural block rather than a thermal insulation block. The second is the increased cement content in the raw material, which increases the thermal conductivity of the walls.”

Peter, 40 years old, Surgut: “The house made of wood concrete is warm. The material is blown through, this was fully evident at the stage of wall construction, immediately after the installation of windows and doors. After finishing the walls, the problem with drafts was eliminated. So, with the right design, the tendency to blow can be made an advantage of the building, since the necessary ventilation of the rooms is ensured. This was my first time working with the material, so I studied the video before starting construction.”

Vitaly, 50 years old, Orel: “Arbolite blocks have been used since the times of the Soviet Union. This is a warm, light and quite durable material. It is non-flammable and does not rot. Made from wood chips and cement, it is also environmentally friendly. It can be used to build private houses and non-residential premises (garages, sheds, warehouses). Wood concrete is plastered on the inside and outside, because is blown. Water passes through it, but this does not affect the properties of the material in any way.”

Its disadvantages

Experts highlight the disadvantage of this material associated with high water absorption, so its use in rooms with high humidity or in areas where precipitation predominates is not recommended. This in no way means that the structure will collapse after rain, like a house of cards, but the service life of the building will be reduced significantly. To avoid this, you need to take some measures to waterproof the structure during the construction stage.

If you use blocks for the foundation, then you definitely need waterproofing and they need to be located at least 0.5 m above the ground level. If you use wood concrete in roof construction, then you must protect the walls from rain with overhangs. Plaster or other finishing will protect the outdoor units from the effects of rain and snow. Among the shortcomings, one can also highlight the imperfect shape of the block, which affects installation and finishing. However, some enterprises began to produce tongue-and-groove blocks, which make it possible to increase their adhesion area, thereby reducing the seams and making installation easier.

Conclusion

In essence, wood concrete slabs are a construction kit from which a durable, warm and environmentally friendly box is assembled at record speed.

The key to a smooth assembly process is a carefully thought out and calculated project. On the websites of the slab manufacturer there are algorithms for calculating walls in cubic meters. A lot of interesting ideas, practical advice and original solutions can be found on the FORUMHOUSE portal.

Details of the construction of houses made of arbolite slabs are in the forum topics “Two two-story houses made of arbolite panels...” and “House made of arbolite panels.” In the article about façade rejuvenation there is a whole selection of materials for all occasions, including cladding for a house made of wood concrete slabs. Ideas for interior decoration can be suggested by articles about modern interior materials, mud plastering or self-leveling floors. The video is about a house made of wood concrete panels for an IT specialist, the construction of which took place thanks to FORUMHOUSE.

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Description and features

The composition of wood concrete includes:

• filler - wood chips, quite strictly limited in size, as well as crushed rice straw, flax seeds, cotton stems, and even pine needles and bark;
• binder – cement of the appropriate brand. This depends on the expected strength of the material, but not lower than M300;
• chemical additives - provide a better connection of components, rapid hardening, and so on. Mainly chloride salts of potassium, calcium, aluminum, as well as “liquid glass” are used.

Wood chips and cement are materials that are difficult to combine with each other, so it is very important to observe all the features of the production technology, in particular, thorough and long-term mixing of the initial mixture.

• The raw material is no less important: the size of the chips is important - no more than 25 mm in length and 10 in width, a certain degree of roughness, the type of wood - spruce, pine, beech, and even the nature of the wood - early or late. If all GOST standards are observed, the material turns out to be porous, “breathable”, but at the same time durable.
• The composition of the starting components affects the result to no less extent. For thermal insulation material, the ratio is usually as follows: 1 share of binder, 1 share of wood chips and 1.5 shares of water, or rather, a solution with salts. To obtain a structural material, the proportion of binder increases within certain limits.
• During production, it is not the proportions that are regulated, but the resulting properties of wood concrete. If they comply with GOST or TU, then the composition is considered suitable for use.

Making wood concrete

Making wood concrete blocks on your own site is not at all difficult. For this you need sawdust, cement, lime or clay, sand. You will also need concrete mixers and molds of the required sizes to pour the mixture.

Let's consider the stages of manufacturing sawdust concrete . The required proportions are shown in the table.

1. Sift the sawdust through a sieve with a mesh size of 1x1 cm.
2. Add sifted sawdust and sand to the concrete mixer. Mix well.
3. Prepare liquid cement-lime mortar in a separate container.
4. Pour the solution into a concrete mixer and mix the resulting composition thoroughly.
5. We pour everything into molds.

Wood concrete blocks made in this way are removed from the mold after a couple of days, and after that they must gain strength within 30 days in a dry room.

Building blocks of grades 5 and 10 are used for insulation, higher grades are used for the construction of walls.

The disadvantage of wood concrete is that it absorbs moisture well, so it must be protected from precipitation. This can be done using plastering. You can plaster the walls only after the structure has completely settled, which is about six months, otherwise the plaster may burst.

A more reliable, but also more expensive method is the use of penetrating waterproofing

Small monolithic structures can be built from sawdust concrete. To do this, first construct the formwork of the required design, into which a mixture of wood concrete is poured.

It is necessary to pour in layers, no more than 15 cm, and each layer must be well bayoneted and compacted.

Such monolithic sawdust concrete gains strength within 3 months.

Reviews

Ivan, Minino: we are building a house from wood concrete. The material was purchased from local suppliers. The walls were built to be forty centimeters thick; no additional insulation was used. External surfaces were finished with siding. The density of the material is good, the fasteners hold well.

Andrey, Saratov: I built a dacha from this material. I did all the work myself, the blocks turned out to be quite light. The house turned out to be two floors, the walls were thirty centimeters long and lined with brick. I was assured that the wood concrete is ventilated, but the indoor climate is always comfortable. Is it worth building with wood concrete? Naturally!

Alexander, Lipetsk: my brother and I built a garage from cast wood concrete. The walls were not reinforced; metal gates were installed. The only inconvenience was that I received the material over two months, two cubic meters at a time. Stock up early!

Zhenya, Sosninsk: built a two-story house. I thought I would use foam concrete, but it was too far to transport. I decided to use poured wood concrete. At first I was worried, but the house is already more than five years old and there have been no problems. Inside, the surface of the walls was plastered and wallpapered. The side of the street was lined with siding panels. I did not install a thermal insulation layer. I decided to find out how to make shavings for wood concrete - I’ll try to make blocks myself.

Having dealt with all the pros and cons of wood concrete, you can argue for a long time about its environmental friendliness, discuss whether wood concrete burns or not, whether it is possible to build with wood concrete in winter.

To the question - is wood concrete harmful to health, we will answer categorically - no. Many people are interested in whether it is allowed to install wood concrete in winter. It is undesirable, since the masonry mortar will set quickly in the cold. It is better to use sheet wood concrete.

Compound

The wood concrete mixture may contain various components. According to GOST 19222-84, wood concrete must consist of several components.

Organic filler – wood chips. To obtain quality blocks, wood particles with dimensions not exceeding 30, 10 and 5 mm in length, width and thickness, respectively, should be used. In addition, the content of polysaccharides in wood should not exceed 2%. The organic filler should not contain fungal elements or various mechanical inclusions. Depending on the type of wood concrete, the wood chip content ranges from 75 to 90%.

Cement binder. Portland cement of a grade not lower than M400 should be used as such a filler. Some manufacturers offer blocks made from frost-resistant cement. It should be noted that during long-term storage, cement blocks lose their original characteristics, which is why they may not meet the requirements stated by the manufacturer.

To avoid such a problem, experienced builders recommend buying wood concrete made of cement no lower than grade M500.

Components of chemical origin. Arbolite blocks partly consist of organic fillers, which tend to rot. To avoid damage to wood chips by fungus, various chemical additives are added to the mixture. These may be calcium or ammonium chlorides, aluminum sulfate or other inorganic substances. Such components are harmless to human health. They allow not only to protect wood chips from premature deterioration, but also to speed up the process of adhesion of the components of the wood concrete mixture, while reducing the drying time of the blocks.

Water is also used to create wood concrete. Its quality is regulated by GOST 23732-79. The water should not contain fats, lipid derivatives, or coloring components. Only fresh liquid is used to produce blocks.

Before starting the technological process, water and chemical components are subjected to laboratory tests. They are carried out regularly for each newly received batch.

Features of masonry walls made of wood concrete

A house built from arbolite blocks can be decorated with facing bricks. The adhesion of bricks and blocks is carried out using steel loops (D=7.50 mm), which are laid in every 5th row with an intermediate distance of 600.0 mm.

Monolithic wood concrete blocks are quite easy to make yourself. This solution will reduce the cost of building materials.

The configuration and dimensions of the blocks are made in accordance with the project or architectural solutions. When additional (trimmed) elements are required, do it or simply, since wood concrete is easily fragmented with a regular saw.

Kinds

According to GOST 19222 84, wood concrete, depending on density, is divided into:

thermal insulation - with an average density of up to 500 kg/m3;

structural - with an average density of over 500 to 850 kg/m3.

Thermal insulation is used as non-load-bearing partitions, in the construction of light one-story buildings, as insulation.

Structural is used for the construction of load-bearing walls in low-rise construction (up to 3 floors).

Arbolite, depending on its compressive strength, is divided into classes:

B0.35; B0.75, B1 - for heat-insulating wood concrete;

B1.5; B2; B2.5; B3.5 - for structural wood concrete.

The compressive strength indicator is characterized by brands:

M5, M10, M15 - for heat-insulating wood concrete;

M25, M35, M50 - for structural wood concrete.

Manufacturers produce several types of this class of concrete. They will be discussed below.

• Building blocks. This group includes thermal insulation and structural materials. These components are used in various fields. The first has a low density, due to which it is used for laying a thermal insulation base during the construction of interior floors. The design option has a density approximately equal to 800 kg / cubic meter. m (due to higher cement content). Due to its higher strength, such wood concrete is used for the construction of load-bearing walls and supporting structures.
• Arbolite slabs. Used as a heat-insulating material. Their density does not exceed 500 kg/cubic meter. m.

• Blocks with decorative cladding. Such products can be finished with marble chips or facing tiles. These materials are much more expensive than conventional blocks. However, the structure with which it was erected does not require further work on the decorative finishing of the façade.
• Solution. It is prepared directly on the construction site and cannot be stored. The solution is used to create monolithic products. Most often it is used for insulating residential premises, much less often - for the construction of small structures. In addition, permanent formwork is made from it for structures whose height does not exceed 3 floors.

• Gypsum wood concrete. Its difference from the usual one is the use of gypsum in the production, instead of Portland cement. It has significant advantages: it does not require the use of chemical components and hardens quickly.

Like any certified building materials, block wood concrete is available in certain sizes. The most popular products are those in the shape of a parallelepiped with parameters of length, width and height equal to 500, 300 and 200 mm, respectively.

Insulation with mineral wool

When the thickness of arbolite walls is about 30 cm, it is recommended to insulate them from the outside with mineral wool. Its layer must be at least 10 cm.

The main advantages of mineral wool include:

• financial accessibility;
• possibility of fastening without arranging sheathing;
• the ability to retain moisture, but not interfere with its evaporation;
• low thermal conductivity;
• fire safety;
• resistance to sudden temperature changes;
• chemical and biological stability;
• high vapor permeability.

If the technology for constructing high-quality vapor and heat insulation is violated, mineral wool will absorb water and lose its thermal insulation qualities.

This material is not used for insulating residential buildings from the inside. Since it releases harmful particles that provoke allergic reactions in people.

The process of installing mineral wool is quite simple. There are two options used here: dry and wet. The first involves laying slabs between the wall and the sheathing. To do this, it is recommended to make a wooden sheathing. The material itself is attached in the spaces between the profiles. The second option involves gluing the slabs to the surface of the walls.

Specifications

The main technical characteristics of wood concrete are presented in the table

Let's now take a closer look at these characteristics.

Density is a fundamental factor in the construction of structures. According to GOST 19222 84, in the production of wood concrete, instead of wood chips, you can use such fillers as hemp and flax kernels, crushed cotton stalks and crushed rice straw. The average density of wood concrete, depending on the type and class, as well as the type of filler, is indicated in the table.

Comparison of density with other building materials:

Although the density of wood concrete is not high, thanks to this, the finished structure will weigh much less than a brick one. And if the weight of the building is light, then you can save on the foundation.

Strength means the threshold value of impact above which the destruction of the material occurs. For example, a cube of wood concrete 150*150*150 (mm) with a density of 600 kg/m3 will withstand a load of more than 8 tons. Important characteristics are bending strength (0.7 - 1 MPa) and elasticity (up to 2300 MPa). Thanks to this, wood concrete stands out from other building materials. Cellular concrete blocks or bricks are brittle materials.

Popular manufacturers and average cost of production

Wood concrete, although lightweight, is still concrete, and therefore it is more profitable for the builder to contact the nearest manufacturer, if, of course, the quality of its products is really worth a good word. Very often, wood concrete is produced using a rather artisanal method, which significantly affects its properties and its reputation.

Most often, companies offering the construction of buildings from wood concrete produce it themselves

• - one of the largest manufacturers in Russia, produces more than 1000 cubic meters. The cost of finished blocks depends on the type of material: the price of thermal insulating wood concrete per piece is 4600 rubles. per cubic meter m, and structural - from 5400 to 6200 rubles. per cubic meter m.
• The wood concrete products plant offers blocks of various sizes. The average cost of products is from 3600 rubles. per cubic meter m.
• The construction and trade company produces solid and hollow wood concrete at a price of 5,250 rubles. per cubic meter. The price here also includes delivery of the material.
• The Velizh house-building company has been producing wood concrete blocks since 2007. The cost of products is from 3900 rubles. per cubic meter m.
• The Vologda wood concrete plant offers structural wood concrete for 4,200 rubles. per cubic meter m.

Major producers of organic concrete

To minimize the risks of construction from wood concrete, it is necessary to purchase only high-quality certified material . There are several manufacturers that have gained popularity in the building materials market:

• (Moscow);
• network of production workshops "Russian Arbolit";
• OKB "Sfera" (Ivanovo);
• Siberian Arbolit (Novosibirsk).

Having our own production facility, equipped with modern automated production lines, allows us to produce material with high quality characteristics. Manufacturers offer affordable prices and convenient terms of cooperation.

Wood concrete is not a new building material. For a long time, the technology was forgotten due to the priority of multi-story residential construction. Now its demand is gaining momentum, since the material satisfies all the conditions necessary for the construction of a private house.

History of wood concrete and wood concrete

Domestic experience in wood concrete production

According to the official version, wood concrete was first discovered by the Dutch in the 1930s. They developed a technology for producing a material called DURISOL. Representative offices of DURISOL appeared in Switzerland and Germany. Wood concrete using DURISOL technology, due to its characteristics and properties, has become known throughout Europe and North America.

Domestic experience in the production of wood concrete begins in 1960, when the Soviet Union, having copied the DURISOL technology, developed it based on GOST materials. Russian wood concrete passes all technical tests, even becoming standardized and certified in the USSR. More than a hundred factories for the production of wood concrete are being built on the territory of the Union, and the material is beginning to be used for the construction of factory buildings, rural houses and farms.

An interesting fact is that in the 60s, wood concrete panels were used in the construction of three buildings and a canteen in Antarctica, at the Molodezhnaya station. Despite the climate, the thickness of the walls was only 30 cm, and this was enough.

In the 80s, the Soviet Union developed a target program called “Arbolit”. Under this program, factories producing building materials begin to operate with a production capacity of 500 thousand m3 per year, and more than 3 thousand buildings are built from Soviet wood concrete.

In the 1990s, a guideline was taken for the construction of houses from blocks and panels based on inorganic aggregate. Arbolite, despite its unique properties, was not widely used in Soviet large-scale housing construction. Some wood concrete factories were destroyed, others were repurposed, and in general this industry was destroyed. And those buildings that were built from wood concrete back in the 60s now stand without losing their original appearance and condition.

Foreign experience in wood concrete production

• DURISOL (Netherlands)

Currently, DURISOL has representative offices in 12 countries, incl. in the Republic of Belarus and the Russian Federation. DURISOL wood concrete consists of coniferous wood chips (80-90% of the total volume), which is treated with mineral additives and Portland cement.

• Duripanel (Germany)

in Germany it produces wood concrete blocks; along with blocks, it also produces wall panels. The panel has a three-layer structure, a rigid base inside and a smooth top layer on both sides. To make panels, wood fibers, mineral additives, water and Portland cement are used as a binder.

• Velox (Austria)

For 50 years, the Austrian company has been producing permanent formwork. The formwork consists of compressed spruce wood chips (95% of the total volume), cement, liquid glass and aluminum sulfate.

• Permax (Japan)

Wood-cement boards "Permax" are produced in Japan. Softwood blanks and waste from plywood production are used as filler, from which longitudinal chips are made on planing machines. The shavings are dried, after which the wood fiber is spread in an even layer on a special spreading machine and impregnated with cement mortar with the addition of mineralizers. In addition to wood fiber, wood chips are used for Permax boards. In Japan, about 20 million pieces of such slabs are produced per year, their production is also developing in neighboring countries (Thailand, Philippines, etc.)

• Centuryboard (Japan and USA).

, specializing in the sawmill industry, organized the production of fire-resistant boards for exterior decoration. The plates are coated with acrylic paint or synthetic resins and have a good appearance.

• Faswall (USA)

produces blocks that consist of Portland cement, wood chips and fly ash. The blocks meet all American standards and have been widely used for 60 years.

• Lignacite ltd (UK)

developed building blocks based on pine sawdust, sand and cement. The blocks are hollow, have good thermal insulation properties, are waterproof, fireproof, frost-resistant and bioresistant. They are used for external and internal walls in low-rise construction.

• Saw concrete (Slovakia)

An effective wall material has been developed in Slovakia. Sawn concrete consists of wood waste - sawdust and shavings from softwood, calcium chloride and Portland cement. It is used for the construction of agricultural and residential buildings, construction of attics. The environmental friendliness and durability of wood concrete allows it to be used in unexpected ways. In Great Britain, the production of birdhouses made of wood concrete was organized.

Optimal equipment for the production of wood concrete

If we quickly collect the prevailing options, we get the following picture:

1. Disc wood chipper, DS31 (Belgorod). Factory price 199 thousand rubles.
   Advantages: compactness, mobility within the workshop.
2. Disadvantages: dependence on power supply.
3. Hammer chopper, DS31 (Stary Oskol). The average cost is 273 thousand rubles.
   Advantages: high productivity.
4. Disadvantages: requires additional capacity for transporting wood chips within the workshop.
5. Rotary chopper, BMP (Vologda). Prices within 230 thousand rubles.
   Advantages: combined type of wood chipper, high productivity.
6. Disadvantages: a certain size of the receiving window, raw materials require adjustment in size.
7. Mixing hopper, BMP (Vologda). Plant price 400 thousand rubles.
   Advantages: sufficient volume for commercial production.
8. Disadvantages: Requires continuous loading to operate effectively, not suitable for small batches.
9. Containers for liquids, IRPLAST (Irkutsk). Cost from 7 thousand rubles per 500 liters.
   Advantages: compact, different shapes, made of polyethylene.
10. Disadvantages: it has to be modified for use with pumps

Naturally, everyone wants the equipment to be:

• powerful;
• compact;
• productive.

However, in reality this is not always the case.

The price of products varies depending on the materials and components used. Two engines of the same power, but produced with different safety margins, will have different prices. The cheaper one will definitely be at risk of breakdown.

The size of the loss is comparable to the cost of the chip cutter itself. Therefore, there is no point in buying a chip cutter that costs less than 150 thousand rubles; these are unreliable options. Equipment produced in Belgorod and Vologda is considered optimal in this industry.

DIY wood concrete

Now we've come to the practical part. It’s one thing when production is designed for mass production, and another thing when everything is done for one’s own use. Here you can already do without expensive equipment.

Let's consider the most common household option, when wood concrete is prepared for building your own house and on your own . Although costs will be significantly reduced, it is important to do everything correctly so as not to maintain the quality of the product.

Equipment

You can’t do without a wood chipper, but you can reduce costs up to 4 times if you order the most important part of a wood chipper from turners .

Almost all lathes have a maximum possible workpiece diameter of 50 cm, so the disk on which the knives will be attached will also have a diameter of 50 cm.

It is better to place the knives at a slight angle, and it is better to place the receiving neck vertically.

The slab or board should fit along the edge, not flat.

For materials for the wood chipper you will need:

• spring from a car;
• studs made of durable metal;
• two bearings per axle;
• the axis itself.

It is better to make it from a hexagon, having previously made seats for the bearings. You can use one of the many videos from the Internet. A competent turner will understand how and what needs to be done. It is quite possible to make the bed yourself.

The standard solution is to install the engine together with a belt tensioner . The casing is welded in place.

However, the best results are obtained by combining a knife and hammer chopper. A disk with knives cuts wood waste into wide plates, unsuitable for use in wood concrete, and a hammer device breaks these plates into narrow thin needles, optimally suited for wood concrete.

The main difference between a hammer grinder and a knife grinder is that the impact on the wood is not exerted by sharp knives cutting the material, but by steel fingers (hammers) freely rotating on an axis .

Large chips cut by knives fall into the next compartment of the chopper, where they are crushed by fingers. In this case, the chips are divided along the fibers, forming thin long needles .

When struck across the fibers, wood separation does not occur, because the strength of the fibers is much higher in the bonds connecting them, even within one annual layer, not to mention the neighboring layers.

By changing the size of the mesh, which screens out insufficiently ground chips, you can obtain
chips of various shapes and sizes .
From rectangular, suitable for smoking (maximum mesh size), to narrow and thin needles (minimum size).

To manufacture such a universal machine you will need:

• shaft;
• cutting disc with knives;
• motor;
• drive unit;
• knife chopper body;
• steel rod with a diameter of 10–20 mm for the pin axes, as well as washers of a suitable diameter, 5 mm thick;
• steel plates 5 mm thick, 20–40 mm wide, 200–300 mm long;
• round or rectangular plates with a thickness of 10–15 mm and a diameter of 200–300 mm;
• stamped steel mesh, the width of which is equal to the width of the body, and the length is 60–80 cm.

One of the conditions that may require a major overhaul of the knife chipper is that the diameter of the knife disk must be 10–30 cm less than the internal diameter of the body, otherwise the chips will be difficult to reach the fingers .

For hammers, you can make 3 or 4 axes, the main thing is that they are all spaced at the same distance from each other, otherwise an imbalance will arise, which will lead to strong vibration of the device.

Creation of a hammer machine

We recommend making a hammer machine like this.

In both disks intended for installing the pin axes, drill holes for them. Place a washer between the blade and the first finger disc . On one side of the pin axles, cut a thread for a standard nut of a suitable diameter.

If it is possible to process the shaft on a lathe, then it is necessary to remove the knife disk from it and remove 5-7 mm from the opposite side, forming a rectangular protrusion, which is necessary for fixing the second disk that holds the axes of the fingers.

You can make two height differences, for the first and second finger disks, but for this, the initial thickness of the shaft must be at least 50 mm, so that after processing its thickness does not decrease less than 30 mm.

If this is not possible, then to fix the second disk you will have to use a sleeve made of a pipe of a suitable diameter, which must be put on the shaft, and from the side of the second disk, cut a thread on the shaft, after which the shaft should be aligned to the diameter of the support bearing.

You will have to use bearings of different sizes - a large one on the side of the knife disk and a small one on the side of the second finger disk, which will complicate the alignment of the shaft. You can use any other methods of fastening the disks that ensure their secure fixation.

Inserting the pin axes into the first disc and setting them at the correct angle, weld them to the disc on both sides. Install and secure the blade disc, then install the disc with the pin axles.

Place pins and washers on the axles, then screw on the inner nut to secure the disc. You need to tighten the nut until the gap between the fingers and the washers is 0.6–0.8 mm .

Place the lock washers on the axles and install the disc, then put the lock washer and nut back on each axle. Tighten the outer nuts to the appropriate torque for their size.

Install the assembled shaft onto the bearings and support. If the outer casing is smaller than required, replace or rework it . The size of the casing should be such that the distance between it and the extended finger is 1–1.5 cm.

The outlet hole must be covered with a steel mesh of suitable diameter.

Bins and forms

The forms offered by manufacturers are standard.

They have dimensions identical to those of foam blocks or polystyrene concrete blocks.

When building a house from wood concrete, blocks with dimensions of 20/40/60 cm are sought or made.

This is the optimal size for most regions.

Cooking molds is a little expensive, so using a grinder you can cut sheets of metal to assemble typesetting molds .

It is desirable that the blocks in these forms are positioned vertically to simplify compaction with a small pressing area.

There is also an option when the finished mixture is directly laid in the formwork, where it is possible to lay reinforcement for the tie . In most cases, masonry mesh . Load-bearing floor slabs cannot be made from wood concrete, but lintels for windows can be made.

After the wood chips have already been chopped and processed, you can begin the direct production of wood concrete. Preparation of wood chips consists of treating it once or twice with a solution of aluminum sulfate or sprinkling it with slaked lime and maintaining the time limit.

If raw wood chips are poured with slaked lime , then this process is optimal when storing wood chips for a period of 2 months or more. If sprayed with lime milk , the aging of the wood chips is reduced by a month.

Aluminum sulfate solution significantly reduces the processing time of wood chips - up to one week. Mixing the wood chips during storage provides ventilation for drying, as well as the removal of small fractions lower to the base of the box. This will allow you to do without sieves and other devices.