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Making lightweight concrete with your own hands. Eco-friendly concrete. Preparing raw materials for making sawdust concrete with your own hands

Sawdust concrete is a lightweight concrete containing cement, sawdust, mineralizers and sand. The material is environmentally friendly, has a low volumetric weight, high stability to fire, low thermal conductivity and high vapor permeability. Used for the construction of monolithic buildings or for the production of building blocks, including used for the construction load-bearing structures, ideal for low-rise construction.

Sawdust concrete can be of several types, depending on density and, accordingly, strength. Each type of material meets the following strength grades: M5, M10, M15, M20. The first two brands are used exclusively as insulation; the construction of load-bearing structures from them is undesirable. The last two grades are used as load-bearing structures in low-rise construction. If multi-storey construction is carried out from sawdust concrete, then the use of a load-bearing frame is mandatory.

Scope of application of sawdust concrete

The material has a wide range of applications, and it is very often made by hand. Using this material, you can build outbuildings; it is also often practiced to build houses from sawdust concrete, insulated walls for the same houses, basements or even bathhouses from sawdust concrete.

The material is relatively light and cheap; in addition, you can save money on the base for the building by using strip foundation. If you reconstruct buildings or insulate them, then there is no need to strengthen the foundation.

Preparing raw materials for making sawdust concrete with your own hands

IN preliminary preparation only the woody part of the composition is needed. First, you need to sift it through a sieve with a mesh size of no more than one square centimeter.

The sawdust can be pre-dried, but this is not necessary. In the future, amendments will simply be made taking into account the moisture content of the sawdust. If you dry it, then the entire volume, not partly!

The most important stage preparation of sawdust is their mineralization. This procedure is carried out to better bind cement to the wood part, making it resistant to fire and biological factors.

Mineralization is carried out by soaking sawdust in a mineralizer solution. It is permissible to use slaked lime as a mineralizer, liquid glass, calcium chloride, calcium sulfate.

Sawdust for the production of sawdust concrete blocks

To prepare the mixture with your own hands, ordinary concrete mixers are practically not suitable; it is much better to use mortar mixers or, in extreme cases, manual mixing with your own hands, which is very difficult for large volumes.

To prepare each grade of material, use its own proportion with the same composition:

• M5 – for this brand, sawdust, lime or clay, sand and cement are used in the appropriate proportion of 4:4:1:1;
• M10 – sawdust, lime or clay, sand and cement are mixed in a ratio of 4:3:4:2;
• M15 – mix sawdust, lime or clay, sand and cement in a ratio of 4:2:7:3;
• M20 - use the following proportion of sawdust, lime or clay, sand and cement 4: 1: 10: 4.

Next, slowly add water, for example, from a bucket or watering can, gradually stirring the mixture until the consistency is crumbly in appearance, but retains its shape after being clenched in a fist, and no moisture should be released.

Superintendent's advice: always take into account the fact that the higher the density, the worse the thermal performance, but the higher the load-bearing capacity finished material.

When producing sawdust concrete with your own hands according to the proposed composition and proportions and then forming it into a finished product, you use pre-prepared forms for blocks the right size. You can also use removable and permanent formwork in case of monolithic construction.

When producing blocks with your own hands, the volume of the already mixed composition is placed in molds coated on the inside with a waterproofing agent. To give the blocks greater strength, longitudinal reinforcement can be placed in the solution. To make the product lighter, you can place vertically located plastic pipes over the entire thickness of the form.

Mold for making sawdust concrete blocks

After pouring, the material is compacted using a vibrating rammer or a specially made manual rammer. Next, without removing the blocks from the mold, they are left covered with cellophane for four days. After this, the tubes are carefully removed from the blocks, and the blocks themselves are removed from the molds and left to dry for a month. After this time, you can build from the blocks, but it is worth considering that full strength is achieved in three months, and there is no need to rush with the cladding.

Foreman's advice: during monolithic construction with removable formwork it is set using the same principles as for block forms. Reinforcement is carried out every 40 centimeters. Permanent formwork is installed together with the reinforcement frame, but it is worth considering that such a structure will take a long time to “dry”.

With a clear calculation of the project, sawdust concrete, even produced with your own hands strictly according to the proposed composition and proportions, is not inferior in quality to factory production. And using it as such has, for the most part, excellent recommendations not only from people who have built with their own hands, but also the same reviews from professional builders.

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2bloka.ru

DIY sawdust concrete

Sawdust concrete is one of the varieties of lightweight concrete with low density. It was developed in the 60s of the 20th century in the Soviet Union and passed absolutely all technical and quality tests, after which it was standardized. Sawdust concrete received widespread use in private housing construction and consumer demand only in the mid-90s, after which its unique properties invariably attract consumers.

The main advantageous characteristics of this building material are:

• environmental Safety;
• fire resistance;
• strength;
• moisture mass ratio;
• vapor permeability;
• thermal performance indicators;
• frost resistance;
• affordable cost of material.

Scope of application of sawdust concrete

This building material is widely used in the construction of houses, dachas, cottages and outbuildings. It is also used in basement insulation and building renovation work. With such reconstruction there is no need to strengthen the foundation.

For the construction of a building made of sawdust concrete, any project created for houses made of other materials is suitable. However, construction costs will be significantly lower. A house built from sawdust concrete is quite light: with an area of ​​250 m2, its weight is about 50 tons. This circumstance makes it possible not to lay a complex foundation. In addition, there are many more advantages, including good sound insulation, ease of assembly, environmental friendliness, cost-effectiveness, long service life.

Composition of sawdust concrete

The basis of this building material, as the name implies, are sawdust. In addition, the composition includes sand, binding materials (sand, lime) and water. Due to its sanitary and hygienic indicators, sawdust concrete is one of the optimal materials for the construction of building walls.

The density of the building material depends on the ratio of sand and sawdust. Accordingly, the density is lower, the smaller the amount of sand used to make sawdust concrete. In this case, they improve thermal properties, but the strength of the material decreases. With an increase in the amount of sand and binders, the strength increases. Frost resistance and water resistance are also improved, which in turn prevents the effects of corrosion on steel reinforcement. Such reinforcement is used when laying walls from blocks made of sawdust concrete. Therefore, before starting production, it is necessary to clearly know the properties of the concrete structure. There are no trifles here, the thickness of the walls, the number of floors, external, interior wall it will either be a supporting structure.

Depending on the composition, sawdust concrete is divided into grades. Blocks of grades M5 and M10 are used for construction, reconstruction and insulation of basements, since they have excellent thermal insulation characteristics. Grades M15 and M20 are best suited for the construction of both internal and external walls of houses.

Brands and proportions of sawdust concrete:

1. M5. For 200 kg of sawdust, take 50 kg of cement, 50 kg of sand, 200 kg of lime or clay. Density – 500 kg/m3.
2. M10. For 200 kg of sawdust, take 100 kg of cement, 200 kg of sand, 150 kg of lime or clay. Density – 650 kg/m3.
3. M15. For 200 kg of sawdust, take 150 kg of cement, 350 kg of sand, 100 kg of lime or clay. Density – 800 kg/m3.
4. M20. For 200 kg of sawdust, take 200 kg of cement, 500 kg of sand, 50 kg of lime or clay. Density – 950 kg/m3.

Making sawdust concrete with your own hands

Blank necessary materials. The good thing about the components that make up sawdust concrete is that they do not need to be prepared in advance. All components can be purchased in stores selling building materials, markets or warehouses. Thanks to this, you can start preparing the workpiece almost one day before the start of production.

Mixing components. Manually preparing sawdust concrete is very labor-intensive process, therefore, to mix the components, if possible, it is advisable to use a concrete mixer or mortar mixer. First of all, the dried sawdust must be sifted through a sieve, the cells of which should be 10*10 millimeters in size. Then the sawdust is mixed with sand and cement. After this, clay or limestone dough is added to the prepared mixture and mixed thoroughly. The resulting mixture is diluted with water, gradually adding it in small portions through a watering can. After each addition, the mixture must be stirred.

If the mixture is prepared correctly and mixed well, then when squeezed in a fist it forms a plastic lump, on which indentations from the fingers are visible, in the absence of drops of water. This is the main sign that the mixture is ready. After this, it can be formed into blocks. In this matter, you should not hesitate under any circumstances, since after 1.5-2 hours the mixture begins to harden. When placing the mixture in the mold, it must be compacted well to eliminate the presence of air.

Block sizes. Such dimensions are not established by standards. They directly depend on the thickness of the walls, the width of the walls and openings, the distance from the openings to the corners of the building, as well as on the installation method. For the greatest convenience during construction, the length of the wall sections or the width of the partitions should be a multiple of the block dimensions.

The thickness of the block is usually equal to two thicknesses of red brick, taking into account the mortar laid between them. In general, this amounts to 140 millimeters. Considering that red baked brick is often used in masonry, this approach is very practical.

Large sawdust concrete blocks take quite a long time to dry. To speed up the drying process, 2-3 holes are made in them, which not only allows the block to dry faster, but also improves the heat-shielding properties of this building material.

Casting molds. Most the best option is the construction of walls not using formwork, but from pre-prepared blocks. They are dried for three months, after which sawdust concrete acquires its original strength. Before starting to prepare the mixture, molds are made for casting the blocks. The form from the sawdust concrete block is not removed immediately, but after three to five days. To speed up the manufacturing process, 10-20 molds are made. This way, the process will not be interrupted, and time will not be wasted waiting for the blocks to dry. The number of molds directly depends on the number of blocks you plan to make at one time.

1. Forms for dimensional blocks. For large blocks, collapsible single or double molds are made. They are made in the form of boxes knocked together from boards. The forms are detachable, which allows them to be disassembled and assembled very quickly. They are made from boards whose thickness is 20 millimeters. The parts of the detachable structure are fastened together using L-shaped steel rods with an M8 thread onto which a wing nut is screwed.
2. Forms for small blocks. For the production of small-sized blocks, they are made in honeycomb forms assembled from 20 mm boards. Basically, such forms are made to produce 9 sawdust concrete blocks at the same time. The number of cells can vary if desired. These forms, consisting of internal and side boards, are just as easy and quick to assemble and disassemble. The inner boards that make up the cells are attached to each other using sliding grooves. The end boards are attached to the side boards with steel L-shaped rods and wing nuts.

Inner walls of molds. To ensure that the boards from which the molds are made do not absorb moisture, internal walls covered with roofing steel, plastic or lined with plastic film. From a mold prepared in this way, the blocks are removed very easily and simply, without sticking to wooden walls.

Considering that the blocks shrink when drying, the forms are made a little large sizes, how the finished blocks should turn out. This difference should be approximately 10%:

1. For solid blocks with dimensions 120*250*140 mm (width*length*height), the box size should be 132*235*154 mm.
2. For blocks with dimensions 190*390*140 mm, the box size is 209*430*154 mm.
3. For blocks with dimensions 130*410*140 mm, the mold size should be 143*450*154 mm.

Production of sawdust concrete blocks

Before filling them with sawdust-concrete mixture, wooden forms are placed on pallets made of steel or plastic, previously sprinkled with a thin layer of sawdust. Wooden plugs wrapped in roofing felt are placed in the mold, which are necessary to obtain through holes. After this, the prepared mixture is tightly placed in the mold, tamping with a specially made manual tamper. After this work, the forms with sawdust concrete are left for 3-4 days. During this time, the building material acquires strength, the percentage of which is 30-40 percent of the brand value.

After the specified period, the plugs and roofing felt are removed, the forms themselves are dismantled, and the blocks are left in the same place for another 3-4 days so that their strength increases further. Now it is 60-70% of brand strength. After this, the blocks should be moved under a canopy for subsequent drying. To achieve the best result, certain conditions must be met:

• It is best to place sawdust concrete blocks in a draft when drying. This way they will dry more evenly;
• when laying blocks for drying, leave gaps between them;
• if there is no canopy, then the blocks must be covered with plastic wrap in case of rainy weather.

For final drying, pillars are constructed from the blocks. It happens like this: two blocks are laid on pre-baked bricks, two more are placed across them, then a couple more are placed across them, and so on. Placed this way, the blocks will finally dry out and harden. The building material acquires 90% strength within a month, but to achieve 100% strength it will take three months.

Completely finished blocks are very durable, hard and free of cracks. Proof of the strength of the building material is that the block does not break when dropped from a height of 1 meter.

sekretystroyki.ru

Making sawdust concrete at home

Currently, many building materials and mixtures have been created that are widely used in different countries world, but still give preference to environmentally friendly clean materials, such as sawdust concrete. It can be easily prepared with your own hands, both in the form of blocks and in the form of monolithic objects for construction.

Sawdust concrete is a type of artificial, lightweight building material. It is made from sand, cement and sawdust, which give it porosity, reduce weight, and provide thermal insulation properties. Sawdust concrete was invented in the 60s of the twentieth century, but its use was not as widespread as it is now.

Blocks made from sawdust concrete are quite reliable and environmentally friendly

Currently, blocks, slabs, and panels are made from sawdust concrete. various sizes. They are used in the construction of cottages, country houses, lightweight upper floors buildings, etc.

Sawdust concrete is an environmentally friendly material, since no toxic substances are used in its production. Its production does not require high energy and financial costs, which ensures the material has a low cost. Sawdust and shavings are used in the production process, which allows us to solve the problem of recycling waste from the woodworking industry. One of the important advantages of the material is its thermal insulation properties, providing reliable protection rooms at low and high temperatures.

The advantage of this material is its low cost and environmental friendliness.

Step-by-step instructions for making sawdust concrete

To make sawdust concrete at home, you will need some tools and materials.

Materials for the production of the product

Materials to be used:

• cement, lime or clay (these are the binding components of the material);
• sand;
• lime;
• sawdust or small shavings.

To form the formwork or mold you will need:

• wooden slats 50 mm, OSB sheets or galvanized metal sheets;
• nails or metal staples to hold the formwork walls.

Tools

Tools you will need:

• hammer;
• tape measure at least 2 meters;
• wood hacksaw;
• screwdriver and screws for it;
• container for the production of sawdust concrete;
• a shovel or a hand-held electric mixer; for large volumes of mixture production, an electric concrete mixer will be needed;
• a trowel or scoop for placing the finished mixture into molds.

There are three main grades of sawdust concrete used in construction: M10, M15 and M25.

• Grade M10 is used in the construction of one-story houses, country houses and outbuildings.
• Brand M15 is used in the construction of two- and three-story houses.
• Brand M25 will help in the construction of industrial and technological buildings and structures.

An important feature of making the mixture is that the mass of binders must be equal to the mass of the dry components of sawdust concrete.

Table of proportions for sawdust production

To make M10 sawdust concrete, take one unit of cement (0.5 buckets), add two units of sand (1 bucket), add six units of sawdust or small shavings (3 buckets) and a little more than half a bucket of lime.

The production of M15 sawdust concrete differs in that 0.5 buckets more sand and one bucket more sawdust are added, the volume of cement remains the same, the amount of lime is reduced to 0.4 buckets. When making a mixture of M25 sand, 1.5 buckets of cement, 0.5 buckets, sawdust 3 buckets and lime 0.4 buckets are added. The volume of water depends on the amount of sawdust concrete. Add enough water to make the mixture paste-like.

In every special case components in sawdust concrete play their role important role, so maintaining proportions is necessary to achieve the production of high-quality material.

Photo gallery: creating blocks step by step

After the mixture has hardened, a few days later, the finished blocks are removed and left to dry for 3–4 months. The mixture is poured into molds and left for several days. The sawdust concrete mixture is brought to a paste-like state. We add all the necessary components and mix thoroughly. We determine the size of the molds and install them for pouring sawdust concrete To produce concrete, it is necessary to purchase sawdust in sufficient quantities

The production of sawdust concrete at home does not represent complex system and actions.

1. We begin to form the formwork or form for the blocks. To make formwork, at the first stage you should decide on the thickness of the walls. It should be at least 50 cm. Using a tape measure, measure the boards or OSB sheets to size, cut them with a hacksaw and secure them with staples or nails on the foundation.
2. Similarly, we form a box for pouring blocks and install it on a flat surface. The dimensions of the box may vary, depending on the use of the blocks.
3. Mixture the right proportions Fill with water and mix thoroughly by hand or using electrical equipment.
4. We bring the mass to a paste and pour it into molds or formwork. A special feature of this concrete is its long drying time of 3 months. This is necessary so that the sawdust loses its chemical activity and the product becomes as strong as possible.

Video: Manufacturing Guide

IN modern world More and more preference is given to environmentally friendly and safe material, such as sawdust concrete. Its production does not require high costs, and the effectiveness of its use has been tested for decades, so if you wish, you can easily make this material at home.

theecology.ru

DIY sawdust concrete for the home: proportions, pros and cons

Sawdust concrete is a material widely used in monolithic construction before the advent of foam concrete. Today, sawdust concrete is most often used to produce wall blocks, which are suitable for the construction of buildings up to 3 floors high.

Sawdust concrete block

This article provides instructions following which you can make sawdust concrete with your own hands. We will also consider the purpose of the material, its technical characteristics, advantages and disadvantages.

Varieties, differences from wood concrete

There are two types of sawdust concrete - structural and thermal insulating, the difference between which is density. Thus, for thermal insulation, medium-density material is used - from 300 to 700 kg/m3, for construction load-bearing walls and structures - sawdust concrete with a density of 700-1200 kg/m3.

Sawdust concrete is often mistaken for wood concrete, but there are significant differences between these materials. What they have in common is the exclusive use of wood derivatives as filler. In this case, in the first case, wood chips are used (particles obtained as a result of crushing wood), in the second, sawdust.

Arbolite is classified as large-porous concrete that does not contain sand. The cement layer in it performs a connecting function; it envelops and glues the chips together. On mechanical strength Arbolite blocks are affected not only by the brand of cement used, but also by the shape of the aggregate - wood chips. The strength of sawdust concrete depends solely on sand-cement mixture. There is a direct relationship between the amount of sand, the strength and thermal conductivity of sawdust concrete - the more sand in the material, the stronger, but at the same time the colder the walls will be.

Sawdust concrete

From the differences in strength characteristics, it follows that a material with a density of 500 kg/m3 can be used as a structural wood concrete, while foam concrete with a density of more than 800 kg/m3 is used for the construction of load-bearing walls. Hence the difference in the thickness of the walls - a house made of sawdust concrete will have almost twice as thick walls as a building made of wood concrete with the same heat-saving ability. In practice, walls made of sawdust concrete are made of a standard thickness, but are additionally insulated.

However, there are differences and advantages. Since the production of sawdust concrete is carried out using wood processing waste, which can be purchased at any sawmill, and for the production of wood concrete blocks it is necessary to process wood in a special way (in rare cases, reeds can be used), the cost of sawdust concrete is much lower, and its production at home is less problematic.

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Pros and cons of the material

Let's consider the advantages of using sawdust concrete blocks as a material for the construction of buildings:

• availability of raw materials;
• simple production technology that can be implemented at home;
• low cost of final products;
• the ability to use sawdust concrete in monolithic construction - the prepared solution is simply poured into the formwork;
• environmental safety - the material contains exclusively natural raw materials;
• light weight and large size of the blocks, which simplifies construction and at the same time speeds up the pace of wall laying.

House made of sawdust concrete

This material also has disadvantages, and they are quite significant. As already noted, this is a low thermal insulation capacity and strength (at low density). However, the key disadvantage is its high hygroscopicity. Sawdust concrete is prone to absorbing moisture, which can cause dampness in the house and the appearance of mold on the walls; moisture absorption also causes a low frost resistance class for the material.

Frost resistance is an indicator on which the service life of the material directly depends. This characteristic indicates the number of freezing/defrosting cycles that it can withstand. The frost resistance of sawdust concrete depends on its density and varies within F25-50.

Considering the above, it is best to use sawdust concrete blocks for the construction of utility buildings - a barn, a garage, a gazebo; a sawdust concrete bathhouse is also a good option, however, for the construction of a house for year-round use, it makes sense to use other materials - aerated concrete, foam concrete.

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Testing sawdust concrete blocks (video)

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Sawdust concrete production technology

The raw material composition of sawdust concrete consists of 4 components - Portland cement, sawdust, sand and water. Lime can also be added as an additional binder, but there is no real need to use it. Cement mortar is an alkaline environment, when it gets into it, sugary substances are released from sawdust, which negatively affect the final strength of the material.

To eliminate negative processes, sawdust must be pre-treated. The easiest way to do this is by keeping the sawdust in the open sun for 2-3 months, however, due to the duration of this method, its use is irrational. The most efficient method is to soak sawdust in lime mortar(concentration 1.5%) for 3-4 days with regular stirring. For a cubic meter of material, it is necessary to use 200 liters of water in which 2.5 kg of lime is diluted. This treatment also protects the blocks from rotting in high humidity conditions.

The proportions of the mixed components depend on the required density of the material being produced (the data in the table is based on the calculation of the preparation of a cubic meter of sawdust concrete):

The amount of water varies between 250-350 l/m3 of the mixture. The specific choice is made based on the initial moisture content of the sawdust. If the humidity of the material is 35-50%, then you need to add the maximum amount of water (350 l), ranges from 50 to 100% - the minimum amount.

Correct consistency of solution

There are two sequences for mixing the solution:

1. Initially, cement and sand are mixed, after which sawdust is added and water is poured.
2. The sawdust is filled with water and cement is added, the mixture is stirred until smooth and sand is added.

Lime is always added last. If the production of sawdust concrete is carried out without special equipment, then it is preferable to use mixing order No. 2 due to its lower labor intensity. Note that preparing such a solution using a gravity-type concrete mixer is quite difficult, since the water will flow down the container, and the sawdust will remain on top. Ideally you should use forced concrete mixer, the cost of which starts from 50 thousand.

An example of a homemade block mold

Handicraft production can be carried out without any special equipment, preparing the solution in a trough. In this case, you need to mix sand and cement with a shovel, then add and mix sawdust and add water. The solution must have such moisture content that when squeezed in a fist it does not crack, but also does not drain with water.

Using such a solution, sawdust concrete screed can be poured or monolithic construction can be carried out. If the ultimate goal is to produce blocks, then you will need to make forms from sheet metal or plywood.

Blocks on drying

It makes sense to make the form to fit the standard size of wall blocks 390*190*188 mm, but at the same time its height should be 5 cm higher, which is necessary for compacting the mixture. Also, the mold should not have a bottom and there should be side handles. For tamping, a separate metal plate is made corresponding to the dimensions of the cross-section of the mold.

The block production technology is quite simple. Initially, you need to prepare a site on which the blocks will be kept until completely hardened; all work is carried out on its territory. The form is filled with sawdust concrete, the lid used as a press presses the mixture, which leads to compaction of the block. Then the form is lifted by the handles and the block remains lying on the floor. The product will gain working strength after 2 weeks.

Saving energy is becoming a necessity, and one of the main expense items in our climate is heating. In this regard, new materials are being developed that make it possible to build warm houses and insulate existing ones. Lightweight concrete is becoming increasingly popular. This is a whole group of materials with a fairly wide range of properties and characteristics.

Types of lightweight concrete

The reduction in concrete mass occurs due to the formation of pores and the use of lightweight aggregates instead of traditional gravel, and sometimes sand. Sometimes pores are formed when various processes are used. Depending on the method of production, lightweight concrete is divided into three groups:

But each group can have many varieties and compositions. Different aggregates and different binders are used. Traditionally, cements are used as a binder (Portland cement materials have better strength characteristics). The second most popular binder is lime; gypsum is used less frequently. Sometimes they can use mixtures of binders and use liquid glass.

Hardening technologies

There are three technologies for producing cellular concrete:

Fillers

Based on their origin, aggregates for lightweight concrete can be divided into two groups: natural (natural) and artificial. Natural ones are obtained by grinding natural porous materials: shell rock, pumice, lava, turf, limestone, etc. The best of them are pumice and volcanic turf. Their pore structure is closed, which reduces the amount of moisture absorbed by the material.

Fillers can be different not only in “origin” but also in size, and often also in shape

Artificial aggregates for lightweight concrete are waste from some technological processes(slag) or materials specially created from natural components (expanded clay, vermiculite, perlite, etc.) as well as some chemical fillers (polystyrene).

Properties, characteristics, application

The main characteristics of lightweight concrete that you should pay attention to when choosing are density (volumetric mass), strength, thermal conductivity and frost resistance.

The density of the material depends mainly on the characteristics of the filler, as well as the consumption of binder and water. It can vary widely - from 500 to 1800, but most often it is in the range of 800-1500 kg/m3. An exception is porous or cellular concrete (foam and aerated concrete). Their density can be from 200 kg/m3.

The main operational characteristic is compressive strength. It is divided into classes, designated in the specification by the Latin letter “B”, followed by numbers. These numbers displays the pressure that a given material can withstand. For example, strength class B30 means that in most cases (according to GOST 95%) it can withstand pressure of 30 MPa. But when calculating, a safety margin of about 25% is taken. And when calculating for class B30, a strength of 22.5-22.7 MPa is taken into account.

At the same time, such a characteristic as the compression limit is used. It is denoted by the Latin letter “M”, and the numbers following it are taken equal to the volumetric mass of concrete in kg/m3.

The thermal conductivity of lightweight concrete is inverse relationship in relation to density: The more air a material contains, the less heat it conducts. This parameter varies within significant limits from 0.07 to 0.7 W/(mx°C). The lightest materials with low density are used as thermal insulation. They cover the walls of buildings and extensions. Insulation of balconies and loggias with foam concrete is very popular. But the greatest economic effect can be obtained when building from lightweight, medium-density concrete. He has sufficient bearing capacity in order to be able to build a two- or three-story house. In this case, no additional insulation is required.

Table of thermal conductivity of lightweight concrete and traditional building materials

Another important characteristic is frost resistance. It is designated by the Latin letter F, followed by numbers, displaying the number of defrost/freeze cycles that the material can withstand without loss of strength. In cases with lightweight concrete, its frost resistance directly depends on the amount of binder in the composition: the more of it, the more frost-resistant the concrete will be.

Purpose

Based on their intended purpose, lightweight concrete is divided into the following groups:

Advantages and disadvantages

If we talk about using lightweight concrete as insulation, there are few disadvantages. The main thing is high hygroscopicity, which, however, varies widely and strongly depends on the filler and type of material. The second not very pleasant moment is the need to select the appropriate finish. If we are talking about exterior finishing (on the street side), then when choosing materials or type of finishing, it is necessary to take into account high vapor conductivity. In this regard, either special steam-permeable plasters are used or cladding is made with a ventilation gap.

But the advantages of lightweight concrete as insulation are more significant. It is easy to install, weighs little, is easy to cut and saw, withstands weather changes well, and does not require the use of wind protection. Add to all this high properties for thermal insulation and low price.

One of the lightweight concretes is polystyrene concrete.

If we talk about the use of lightweight concrete as a material for building houses, their advantages are as follows:

As you can see, lightweight concrete has a lot of advantages as a building material. But not everything is so rosy. There are disadvantages that you should be aware of to make an informed decision:

• To increase the strength of walls, frequent reinforcement is necessary. These are additional costs for materials and time for laying reinforcement.
• Insufficient resistance to cracking. The heterogeneous structure of the material leads to the fact that in the presence of uneven loads (uneven shrinkage of the foundation, for example), cracks appear in the blocks. If they are thin—web-like—they do not affect the strength of the structure, although they look terrifying.
• High moisture absorption. The thermal insulation characteristics of damp materials are reduced significantly. Therefore, during construction it is important to make high-quality waterproofing. If you plan to use it in conditions high humidity, it is recommended to use pumice, agloporite and expanded clay as fillers.
• The low density of materials leads to the fact that fasteners do not hold well in such walls. The material withstands vertical loads well, but does not hold up well to pull-out loads. For lungs and cellular concrete developed special fasteners, but the best solution is to install mortgages in places where heavy objects are supposed to be attached.
• Difficulty of choice exterior finishing. As already mentioned, this is either cladding with a ventilated facade, or special plasters.
• For interior decoration High-quality preliminary priming of the walls may be required for better adhesion to plaster or putty.
• Low degree of sound absorption. Due to the large number of voids and concrete “paths” running between them, sounds are transmitted very well. For normal sound insulation, the use of additional materials is required.

Most of the shortcomings are rather operating features, but they must be taken into account. Then there will be no unpleasant surprises, and all features will be taken into account at the planning stage.

Where and how to use it on a construction site, examples of making it yourself

As can be understood from all that has been said, lightweight concrete can be used for any structure. They are used to build walls, use them as insulation, pour slabs for floors, and make screeds. But all these tasks require different characteristics. They are “recruited” by selecting components.

How to choose a recipe

For example, for a floor screed you need strength, hydrophobicity and low thermal conductivity. Strength and reduction in the amount of absorbed moisture is achieved by using Portland cement as a binder. Since the best natural additives that ensure low moisture absorption - pumice and volcanic turf - cannot be called publicly available, expanded clay or polystyrene balls can be used to increase thermal conductivity. They also absorb little moisture.

Now about the proportions. They are taken standard for a given brand. And depending on the type chosen (sandless or regular), the aggregate is replaced. Most often used for floor screeding normal lungs concretes. In them, gravel is replaced with the selected aggregate, which is added in the required proportion. Only less water is taken, making the solution so dense or fluid that it can only be laid.

Even in production, the exact composition of lightweight concrete is determined experimentally each time. This is due to the fact that aggregates have very different characteristics both in terms of mass, density and other parameters. Make several small batches with different compositions of aggregate (coarse, fine, their proportions, combine several different types of aggregate) and different amounts water. After hardening, it is determined which of them is better suited for a specific task. Using the same method, you can independently determine how much and what kind of filler is best to pour, and then mix large volumes.

An example of attic insulation with polystyrene concrete

For an example of experimental selection for specific tasks, see the video. It was necessary to select a composition for insulation attic floor. It was decided to use polystyrene concrete as it is warm and light. A sand-free composition was chosen and only polystyrene balls were poured as filler.

According to the chosen recipe, lightweight concrete was mixed and the attic was insulated. The process can be seen below.

But this composition is only suitable for insulation in places with little load. If you need a screed thermal insulation characteristics on the floor, take the traditional recipe with sand, and replace the filler with polystyrene balls. To increase the strength characteristics, reinforcing fibers, such as fiber, can be added. To improve plasticity, you can add, as in the video fragment, a certain amount detergent for dishes or liquid soap. In general, the optimal composition must be determined experimentally.

An example of pouring a polystyrene concrete screed can be seen in the following video. There is no news, except for a different composition: there is sand. The result will be a more uniform structure with cavities filled with concrete mortar and small air bubbles.

What else you need to know is that it is better not to use crumbs for the production of polystyrene concrete. For normal characteristics, you need balls, and not just any balls, but those that will adhere well to the solution. They have a durable film on the surface and do not absorb cement laitance, which is why they have good thermal insulation properties. The crumbs obtained by grinding defective slabs have an uneven and torn structure. As a result, it is impregnated with cement laitance. Naturally, such concrete will be warmer than regular concrete, but not as warm as granulated concrete.

Expanded clay concrete in private housing construction

Another popular filler for producing lightweight concrete at home is expanded clay. It is made of clay to which substances have been added that expand in volume when heated. This composition is loaded into ovens, where swelling occurs and subsequent firing. But, as studies have shown, many clays emit radiation; as a result, expanded clay also has a radiation background, sometimes even unsafe for health. So you need to be prepared for his choice - have a dosimeter.

The procedure for selecting the composition here is similar to that described above. Only the ability to change the proportions of the large and medium fractions is added. You can also add sand or not and get results that differ in structure and characteristics.

Expanded clay concrete is used for pouring into molds and producing building blocks, and it is also possible to erect walls with adjustable formwork. Unlike expanded clay concrete blocks, this technology can be used for the construction of load-bearing walls.

And in this video - the experience of living in a house made of monolithic expanded clay concrete.

Houses made of sawdust concrete - wood concrete

Another natural filler that costs mere pennies and can be used for private house construction is sawdust, or rather shavings with sawdust. A very fine fraction is unsuitable for this material; waste from rounding of medium or large size is needed.

The composition in this case is sandless, but the proportions are maintained: 6-7 parts of aggregate are taken for 1 part of concrete. In this case - sawdust. To increase the hydrophobicity of the composition, add liquid glass or calcium chloride.

Second version of kneading and proportions

Here are reviews from residents

Concrete mortar is the most important component in the construction of foundations, and the durability of the entire structure depends on its quality. It is not always possible to order ready mixture, and therefore it is advisable to know how to make concrete with your own hands. Here it is important not only to maintain proportions, but to select the components correctly, otherwise the strength of the solution will not be high enough.

Characteristics of concrete

Strength

Concrete mortar is a mixture of cement, sand, filler and water in certain proportions, which vary depending on the purpose of the concrete and the brand of cement. If necessary, plasticizers are added to the solution. The most important characteristic of concrete is its compressive strength, which is measured in MPa (mega pascals). It is according to this indicator that concrete is divided into classes. But the grade of concrete indicates the amount of cement in the solution.

Concrete class	Average strength of this class, kg s/sq.cm	Nearest brand of concrete
AT 5	65	M 75
B 7.5	98	M 100
AT 10	131	M 150
At 12.5	164	M 150
At 15	196	M 200
IN 20	262	M 250
At 25	327	M 350
At 30	393	M 400
At 35	458	M 450
At 40	524	M 550
At 45	589	M 600
At 50	655	M 600
At 55	720	M 700
At 60	786	M 800

M100 and M150 (B7.5 and B12.5) are most often used as a layer under the main foundation, for the manufacture of screeds, and concreting paths. Concrete M200-M350 is most in demand: it is used in the construction of foundations, for the manufacture of screeds, concrete stairs, blind area. Mortars of higher grades are used primarily in industrial construction.

Plastic

An important characteristic of concrete is its plasticity. The more plastic the solution, the better it fills the formwork structure. When the mobility of concrete is low, unfilled areas remain in the screed or foundation, which leads to gradual destruction concrete slab. For standard structures, concrete with plasticity P-2 or P-3 is used, for formwork of complex shapes and in hard to reach places It is recommended to use solution P-4 and higher.

Waterproof and frost-resistant

Water resistance depends on the amount and brand of cement in the solution. The higher the grade, the more resistant the concrete is to moisture. Frost resistance of concrete is achieved by adding plasticizers to the composition. It should be noted that these set very quickly; if you incorrectly calculate the amount of the mixture or use it at a low temperature, the concrete will turn into a monolithic block right in the container.

Concrete components

Cement performs a binding function for all other components of the concrete mortar, and the strength of the concrete itself directly depends on its quality. In private construction, cement grades M400 and M500 are most in demand. When purchasing cement, you should be aware that it loses its qualities over long periods of time or improper storage. Already a month after production, the binding properties of cement decrease by 10%, after six months - by 50%, after a year it is not recommended to use it at all. But even fresh cement will become unsuitable for use if it becomes damp, so it must be stored in a dry place.

Sand is the second most important component of concrete mortar. In rare cases, it is replaced with slag, while standard concrete is always mixed with sand. It is best to use coarse grain river sand without various impurities. If only the regular one is available fine sand, it should not contain clay, earth or silt, which reduce the adhesion of the solution to the filler. Before mixing, the sand must be sifted to remove all excess.

Aggregate

The best aggregate for concrete mortar is considered to be sizes from 5 to 35 mm. Often crushed stone is replaced with gravel, and a little less often with expanded clay. It is very important that the surface of the aggregate is rough, then its adhesion to the cement will be as strong as possible. To compact the mixture, you need to take aggregate of different fractions. Like sand, the aggregate must be clean, so it should be poured onto a prepared and compacted area or on a spread tarp.

Supplements

To give concrete frost resistance, water resistance and other useful properties plasticizers are used. They ensure the setting of the solution at low temperatures, increase its plasticity or, conversely, impart viscosity. They should be used only if it is really necessary, and you should strictly adhere to the instructions for their use and observe the proportions.

If a thin or unstable screed is required, concrete mortar reinforcing fibers are mixed. They are made of polyvinyl chloride and polypropylene; they have low strength, but are excellent at avoiding cracking of concrete. In standard foundations and screeds, reinforcing substances are not needed.

Prices for cement and basic mixtures

Cement and base mixtures

Solution proportions

To make high-quality concrete yourself, you need to know in what proportions to mix the components. Most often, the ratio of cement, sand and crushed stone is used as 1: 3: 6; At the same time, they take half as much water as total weight dry ingredients. It is recommended to add water not all at once, but in several portions, this makes it easier to control the density of the solution. The humidity of the sand also matters - the higher it is, the less water is required. All components must be measured in one container, for example, a bucket. When using containers of different sizes, it will not be possible to achieve the desired proportions.

When mixing, the purpose of the solution should be taken into account. For the substrate under the screed, lean concrete is made without adding crushed stone; for concreting paths and blind areas, crushed stone of medium and fine fractions is used; for the foundation of a house, medium-fraction crushed stone and cement are used. High Quality. The table will help you find out the exact different brands.

Manual method of mixing concrete

Mixing the concrete solution is carried out manually or in a concrete mixer. If you need to fill large area, the first method is not suitable, as it will take too much time and physical effort. If you need a little solution, it is more convenient to knead it by hand.

Step 1. Preparation

To prepare the solution, you will need a low, wide container, for example, a large metal trough, a picking shovel, a bucket and a regular hoe.

Step 2: Dry Mixing

A bucket of cement is poured into the container, then 3 buckets of sifted sand and 5 buckets of crushed stone. The dry ingredients are thoroughly mixed with a hoe. The proportions may be different, depending on the required brand of solution.

Step 3: Adding Water

If all ingredients are mixed evenly, you can add water. First, pour out 7-8 liters and begin to intensively stir the contents with a hoe. This process will require effort, but you need to stir it very well. It is advisable to lift the bottom layer and run the hoe into the corners where dry lumps may remain. If the solution is very thick and sticks to the hoe, you need to add a little water. Properly prepared concrete slides off the shovel slowly and does not delaminate.

There is another mixing option: first, water is poured into the container, then cement is poured. For 2 buckets of water you need 2 buckets of cement. Thoroughly mix the cement with water and add 4 buckets of sand. Mix well again until smooth. Lastly, add crushed stone in the amount of 8 buckets and mix again. There is no clear opinion on which method is better, so it’s worth trying both and determining the most optimal one for yourself.

Find out the correct proportions, how to make them yourself, from our new article.

If the resulting concrete is too thick, add a little cement to the remaining water, mix well and pour into a concrete mixer. It is not recommended to stir the solution for more than 10 minutes, otherwise the cement will begin to set. Ready concrete is poured directly onto the site or into a wheelbarrow if the concrete mixer is located at a distance. It is advisable to pour out the entire solution at once, but if this does not work, leave part of the mass in the turned on concrete mixer. It should be used as soon as possible.

Prices for popular models of concrete mixers

Concrete mixers

Video - How to make concrete with your own hands

Everything has already been created by nature. We can only use its tips when developing high-tech materials. This is the path taken by the developers of permeable concrete that imitates natural soil.

Everything has already been created by nature. We can only use its tips when developing high-tech materials.

This is the path taken by the developers of permeable concrete that imitates natural soil. Permeable concrete is a highly porous material made from concrete particles glued together. The pore space occupies 15-25% of the total volume of the material. The result is a cheese with a lot of holes. High porosity ensures the filtration of large volumes of water - up to 200 liters per minute per 1 m2 of coating. What are the advantages of this technology?

There is a natural water cycle in nature. Rainwater reaches the surface, is absorbed by plant roots, and excess flows into groundwater. Next, the water evaporates through the leaves of plants and from the surface of reservoirs that are fed by groundwater. In cities where the asphalt has literally “gobbled up” the entire surface, rainwater is transported outside the city through drainage systems. As a result, the natural cycle is disrupted. Plants suffer from lack of water, and groundwater does not receive proper nutrition. Permeable concrete, unlike asphalt, allows rainwater to pass through, thereby ensuring its free access to the soil. At the same time, the load on the city's drainage systems during rainy seasons is reduced.

The cost of such a coating is significantly lower than asphalt. Don’t forget that a quarter of the “miracle concrete” is air. On the other hand, asphalt is a petroleum product. In addition to the unstable cost of its production, asphalt contains a large amount of toxic substances that pollute the environment.

Eco-friendly concrete is ideal for harsh environments climatic conditions. Due to its porosity, unlike asphalt, it is resistant to temperature changes. This eliminates the need for frequent road repairs, and in our realities, the annual relaying of the asphalt surface. Manufacturers of “miracle concrete” guarantee 15 years of operation in such conditions!

Porous concrete is used in the USA and Europe to build sidewalks, parking lots, highways, pavements in recreation areas, retaining walls and strengthening slopes. Manufacturers are confident that over time the scope of its application will expand.

The developers of the Portuguese studio e-studio went even further. They "revitalized" concrete by adding seeds to it lawn grass. Organic concrete is a unique material that, due to its porous structure, allows seeds to germinate directly from this substrate. Even during dry periods, plants will not lack water, securely stored in its pores.

Organic concrete opens up new possibilities for architects and landscape designers. In fact, the originality of “green structures” and living forms is limited solely by their imagination.

Comments:

Lightweight concrete has a fairly high porosity (about 35-40%), medium density(from 150 to 1800 kg/m³), low cost and ease of manufacture. It has become widespread and is used in the construction of monolithic and prefabricated, enclosing and load-bearing structures, as well as thermal insulation. This material has a relatively light weight and good heat-shielding properties, although it is inferior in strength to brick and heavy concrete.

When using it, you can significantly reduce the thickness and weight of the walls being constructed. As a result, construction costs will be significantly reduced.

Lightweight concrete is a concrete mixture of cement, water, sand and large porous aggregates.

Main characteristics

Such concretes are usually made by mixing various binders, light porous materials and water in certain proportions, sometimes with the addition of sand, foam and gas formers, water repellents, plasticizers, antiseptics, etc.

Various types of cement (magnesium cement, Portland cement), gypsum, lime, and cement-lime mixtures are usually used as a binding element.

1. The following can be used as fillers:
2. Light natural materials from rocks with a porous structure (dolomite or limestone of volcanic origin, pumice, shell rock, opoka, etc.), obtained by crushing and fractionating them. Artificial materials obtained from waste from metallurgical, coke-chemical, and oil refining production, when processing waste in city household landfills. Fuel, metallurgical and chemical slags are used without any preliminary processing. Expanded expanded clay, vermiculite, and perlite are obtained by special firing of clay raw materials. At high temperature
3. and rapid heating, products expand 17-40 times.

Organic materials such as softwood sawdust, flax or hemp brome, etc.

To improve the strength characteristics of lightweight concrete, sand can be added to the mixture.

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Basic properties of porous lightweight concrete

1. The density of the material, which depends mainly on the dry bulk density and the fraction of the aggregate used. A coarse aggregate is considered to be from 5 to 40 mm in size, and a small aggregate is from 0.2 to 5 mm. The ratio of coarse to fine aggregate should be 6:4. On average, the ratio of the bulk density of coarse dry aggregate to the density of the concrete produced from it is approximately 1:2. The following grades of lightweight concrete are available depending on the volumetric mass: D200, D300, D400..D2000 (with an interval of 100 kg/m³). The density decreases as the cement stone becomes porous.
2. Strength directly depends on the amount and brand of cement used in the mixture, as well as on the quality of porous aggregates. If the strength of the aggregate used is low, then it may well start with it, regardless of the characteristics of the cement stone. Concrete compressive strength classes have been established from B0.35 to B40, depending on their purpose.
3. Thermal conductivity can vary within a fairly wide range from 0.055 to 0.75 W/(mx°C). This value is significantly influenced by both the density of the concrete itself and the nature of the porosity structure and moisture content of the material. If volumetric humidity increases by 1%, then thermal conductivity increases by 0.01. 0.03 W/(mx°C). Excellent thermal insulation properties are obtained by using lightweight polystyrene foam fillers (coefficient from 0.055 to 0.145 W/(mx°C)) and expanded perlite with a coefficient of 0.15 W/(mx°C) at a density of D600.
4. The frost resistance of a material directly depends on quality characteristics aggregates and binders, the structure of the concrete also plays a huge role. Frost resistance varies from F15 to F200. You can get values ​​up to F300 and even F400. Typically, such concretes are used for external structures;
5. Water resistance depends on the type of binder, the ratio of it to water in concrete, the content of various chemical and finely ground additives, the conditions under which hardening occurred, and the age of the concrete itself.

It is quite high, and as the material ages it increases more and more. Depending on water resistance, the following grades of lightweight concrete are distinguished: W2, W4, W20 (numbers indicate pressure in kgf/cm²).

To improve the strength characteristics of lightweight concrete, sand can be added to the mixture.

Difference in structural features

The following types of lightweight concrete are distinguished:

1. Ordinary ones, which are usually made from fine or coarse aggregate, water and a binder, in which case the solution almost completely fills the various voids between the large particles. The air involved in such a mixture should not exceed 6% of the total volume.
2. Sandless, large-porous: in such concrete, between the particles there are voids free from mortar. The structure contains more than 25% of pores filled with air.
3. Porous or usually made from a binder base and special pore-forming additives. In their structure, so-called closed cells appear, filled with gas or air (up to 85% of the volume). Such materials may lack sand and coarse aggregates.

To improve the strength characteristics of lightweight concrete, sand can be added to the mixture.

Division by purpose

Lightweight concrete with porous aggregates can be divided into the following types:

1. Thermal insulation with thermal conductivity up to 0.2 W/(mx°C) and volumetric mass from 150 to 500 kg/m³, which are used for the production of special thermal insulation structures and as slabs for insulation.
2. Structural and thermal insulation, the volumetric mass of which is from 500 to 1400 kg/m³, their compressive strength should be M35 and higher, and thermal conductivity - 0.6 W/(mx°C), no more. They are usually used for the construction of enclosing and some load-bearing structures (various floors, walls and partitions).
3. Structural ones have the highest volumetric mass for lightweight concrete (from 1400 to 1800 kg/m³), have a strength of more than M50 and frost resistance of at least F15. These are usually used for load-bearing external structures.

A fairly durable and relatively lightweight material, concrete, can be made with your own hands using metallurgical or fuel slag. It is used for monolithic construction; small blocks can be made from it. And then use them to build walls using cement mortar.

Such blocks are usually produced in a factory, but they can also be made directly at construction site, preparing formwork forms and pouring concrete made with your own hands from slag into them. When casting blocks yourself, in order to reduce thermal conductivity and save cement, you can even use paper sleeves (old newspapers) filled with sand, as well as special inserts made of lighter sawdust or polystyrene concrete, as void formers. Lightweight concrete grade M10 can be used for such thermal inserts.

To obtain blocks, you can make concrete with your own hands, using sawdust as a filler. The construction of walls from such material significantly reduces the cost of the entire construction. If such walls are well protected from weathering, they will last more than 50 years.