Lightweight concrete with your own hands. How to make colored concrete with your own hands. Required amount of water

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

Sawdust concrete can be of several types, depending on the 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 a heater, the construction of load-bearing structures from them is undesirable. The last two brands 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 supporting frame is mandatory.

Scope of application of sawdust concrete

The material has the widest range of applications, while it is very often made by hand. With the help of this material, it is possible to build outbuildings, it is also often practiced to build houses from sawdust concrete, insulating walls for the same houses, basements, or even saunas from sawdust concrete.

The material is relatively light and cheap, in addition, you can save money on the foundation for the building using a strip foundation. If you carry out the reconstruction of buildings or insulate them, then there is no need to strengthen the foundation.

Do-it-yourself preparation of raw materials for the manufacture of sawdust concrete

Only the woody part of the composition needs preliminary preparation. To begin with, it must be sifted through a sieve with a mesh size of no more than one square centimeter.

Sawdust can be pre-dried, but this is not necessary. Subsequently, amendments will simply be made taking into account the moisture content of the sawdust. If dry, then the entire volume, and not partially!

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

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

Sawdust for the production of sawdust concrete blocks

Conventional concrete mixers are practically not suitable for preparing a mixture with your own hands, 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.

For the preparation of each of the grades of the material, their proportion is used 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 mixing the mixture until a crumbly-looking consistency is obtained, but retains its shape after being compressed in a fist, while no moisture should be released.

Foreman's advice: always consider the fact that the higher the density, the worse the thermal performance, but the higher the bearing capacity of the finished material.

In the production of sawdust concrete with one's own hands according to the proposed composition and proportions, followed by its formation into a finished product, pre-prepared forms for blocks of the desired size are used. It is also possible to use removable and non-removable formwork in case of monolithic construction.

In the production of blocks with their own hands, the volume of the already mixed composition is placed in molds coated from the inside with a waterproofing agent. To give the blocks greater strength, longitudinal reinforcement can be placed in the solution. To facilitate the product, vertically located plastic pipes can be placed over the entire thickness of the mold.

Form for the production of sawdust concrete blocks

After pouring, the material is compacted with a vibrotamper or a specially made manual rammer. Further, without removing the blocks from the mold, they are left covered with cellophane for four days. After that, the tubes are carefully removed from the blocks, and the blocks themselves are left to dry for a month. After this time, blocks can be built, but it should be borne in mind that full strength is achieved in three months, and there is no need to rush with facing.

Foreman's advice: in monolithic construction with removable formwork, it is installed using the same principles as for block forms. Reinforcement is carried out every 40 centimeters. The fixed formwork is installed together with the reinforcing cage, but it should be borne in mind that such a structure will “dry” for a long time.

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

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2bloka.ru

Do-it-yourself sawdust concrete

Sawdust concrete is one of the varieties of lightweight concrete with a reduced 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 mass application 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;
mass ratio of moisture;
vapor permeability;
thermal performance;
frost resistance;
affordable cost of the material.

Scope of sawdust concrete

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

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

Composition of sawdust concrete

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

The density of the building material depends on the ratio of sand and sawdust. Accordingly, the density is the less, the smaller the amount of sand went to the production of sawdust concrete. In this case, the thermal properties are improved, but the strength of the material is reduced. With an increase in the amount of sand and binders, strength increases. Frost resistance and water resistance are also improved, which in turn prevents corrosion of steel reinforcement. Such reinforcement is used when laying walls from blocks made of sawdust concrete. Therefore, before proceeding with the manufacture, it is necessary to clearly know the properties of the concreted structure. There are no trifles here, the thickness of the walls, the number of floors are taken into account, whether it will be an external or internal wall or a supporting structure.

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

Grades and proportions of sawdust concrete:

M5. For 200 kg of sawdust, 50 kg of cement, 50 kg of sand, 200 kg of lime or clay are taken. Density - 500 kg / m3.
M10. For 200 kg of sawdust, 100 kg of cement, 200 kg of sand, 150 kg of lime or clay are taken. Density - 650 kg / m3.
M15. For 200 kg of sawdust, 150 kg of cement, 350 kg of sand, 100 kg of lime or clay are taken. Density - 800 kg / m3.
M20. For 200 kg of sawdust, 200 kg of cement, 500 kg of sand, 50 kg of lime or clay are taken. Density - 950 kg / m3.

Making sawdust concrete with your own hands

Preparation of the necessary materials. The components that make up sawdust concrete are good because they do not need to be prepared in advance. All components can be bought in stores selling building materials, in markets or warehouses. Thanks to this, the preparation can be started almost one day before the start of production.

Mixing components. Manual preparation of sawdust concrete is a very time-consuming process, so it is advisable to use a concrete mixer or mortar mixer to mix the components, if possible. First of all, dried sawdust must be sieved through a sieve, the cells of which should be 10 * 10 millimeters in size. The sawdust is then mixed with sand and cement. After that, 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. Stir the mixture after each addition.

If the mixture is prepared correctly and well mixed, then when squeezed in a fist, it forms a plastic lump, on which dents from the fingers are visible, in the absence of water drops. This is the main sign of the readiness of the mixture. After that, it can be formed into blocks. In this case, it is impossible to hesitate in any case, since after 1.5-2 hours the mixture begins to harden. When laying the mixture in the form, it must be well tamped to exclude the presence of air.

Block sizes. Such dimensions are not established by the 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 walls 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 is 140 millimeters. Considering that red burnt brick is often used in masonry, this approach is very practical.

Large sawdust concrete blocks dry for a long time. 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. The best option is to build walls not with formwork, but from pre-prepared blocks. They are dried for three months, after which the sawdust concrete acquires its branded strength. Before starting the preparation of the mixture, molds for casting blocks are made. 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. Thus, the process will not be interrupted, and time will not be wasted waiting for the blocks to dry. The number of forms directly depends on the number of blocks that you plan to make at a time.

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

Inner walls of molds. So that the boards from which the casting molds are made do not absorb moisture, the inner walls are upholstered with roofing steel, plastic or laid with plastic wrap. From the form prepared in this way, the blocks are removed very easily and simply, without sticking to the wooden walls.

Considering that the blocks shrink during drying, the forms are made a little larger than the finished blocks should be. This difference should be approximately 10%:

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

Production of sawdust concrete blocks

Wooden forms, before being filled with sawdust-concrete mixture, are placed on pallets made of steel or plastic, previously sprinkled with a thin layer of sawdust. Wooden plugs wrapped in roofing paper are placed in the mold, which are necessary to obtain through holes. After that, the prepared mixture is tightly laid in a mold, while tamping with a specially made manual tamper. After carrying out these works, the molds 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.

After the specified period, the corks and roofing are removed, the forms themselves are disassembled, and the blocks are left in the same place for another 3-4 days, so that their strength increases even more. Now it is 60-70% of brand strength. After that, the blocks should be moved under a canopy for subsequent drying. To achieve the best result, some conditions must be observed:

when drying, sawdust concrete blocks are best placed in a draft. So their drying will be carried out 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, poles are constructed from blocks. It happens like this: two blocks are laid on pre-fired bricks, two more blocks are placed across them, then a couple more across and so on. Placed in this way, the blocks will finally dry out and harden. Building material acquires 90% strength in a month, however, it will take three months to achieve 100% strength.

Completely finished blocks are very strong, hard and do not have cracks. Proof of the strength of the building material is that the block does not break when dropped from a height of up to 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 of the world, but still preference is given to environmentally friendly 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 refers to a variety of artificial, lightweight building materials. 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 of sawdust concrete are quite reliable and environmentally friendly.

At present, blocks, slabs, panels of various sizes are produced from sawdust concrete. They are used in the construction of cottages, country houses, lightweight upper floors of 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 provides the material with a low cost. Sawdust and shavings are used in the production process, which allows solving the problem of woodworking industry waste disposal. One of the important advantages of the material is its thermal insulation properties, which provide reliable protection of the premises at low and high temperatures.

The advantage of this material lies in 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 binder components of the material);
sand;
lime;
sawdust or small shavings.

To form a formwork or form, you will need:

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

Tools

Of the tools you will need:

a hammer;
tape measure at least 2 meters;
wood saw;
screwdriver and screws to it;
capacity for the manufacture of sawdust concrete;
a shovel or a hand-held electric mixer; for large volumes of mix production, you will need an electric concrete mixer;
trowel or scoop for laying the finished mixture into molds.

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

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

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

Table of proportions for the manufacture of sawdust

For the manufacture of M10 sawdust concrete, we take one unit of cement (0.5 buckets), add two units of sand (1 bucket), add six units of sawdust or small chips (3 buckets) and a little more than half a bucket of lime.

The production of sawdust concrete grade M15 is different in that 0.5 buckets more sand is added and more sawdust per bucket, the volume of cement remains the same, the amount of lime decreases to 0.4 buckets. In the manufacture of a mixture of grade 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 mass a paste.

In each individual case, the components in sawdust concrete play an important role, so that proportions are necessary to achieve the production of a quality material.

Photo gallery: creating blocks step by step

After the mixture has hardened, after a few days, the finished blocks are removed and left for 3–4 months to dry The mixture is poured into molds and left for several days The mixture of sawdust concrete is brought to a pasty state Add all the necessary components and mix thoroughly We determine the size of the molds and mount them for pouring sawdust concrete For the production of concrete, it is necessary to purchase sawdust in sufficient quantities

The production of sawdust concrete at home is not a complex system and actions.

We proceed to the formation of formwork or molds for blocks. For the manufacture of formwork at the first stage, it is necessary to determine the thickness of the walls. It should be at least 50 cm. With a tape measure, we measure boards or sheets of OSB in size, cut it off with a hacksaw and fix it with staples or nails on the foundation.
In a similar way, we form a box for pouring blocks and install it on a flat surface. The dimensions of the box may be different, depending on the use of the blocks.
Pour the mixture of the required proportions with water and mix thoroughly manually or with the help of electrical equipment.
We bring the mass to a state of paste and pour it into molds or formwork. A feature of such concrete is its long drying for 3 months. This is necessary so that the sawdust loses its chemical activity and the product becomes as strong as possible.

Video: Making guide

In the 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 proven for decades, so if you wish, you can easily make this material at home.

theecology.ru

Do-it-yourself 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 heat-insulating, the difference between which lies in the density. So, for thermal insulation, medium-density material is used - from 300 to 700 kg / m3, for the construction of load-bearing walls and structures - sawdust concrete with a density of 700-1200 kg / m3.

Often, sawdust concrete is mistaken for wood concrete, but there are significant differences between these materials. The only thing they have in common is the use of tree derivatives as a placeholder. At the same time, in the first case, wood chips are used (particles obtained as a result of crushing a tree), in the second, sawdust.

Arbolit is classified as coarse-pored concrete that does not contain sand in its composition. The layer of cement in it performs a connecting function, it envelops and glues the chips together. The mechanical strength of arbolite blocks is 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 the 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 composition of the material, the stronger, but the walls will be colder.

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 capacity. In practice, the walls of sawdust concrete are dressed with a standard thickness, but at the same time they are additionally insulated.

However, there are some differences and advantages. Since the production of sawdust concrete is carried out using woodworking waste, which can be bought at any sawmill, and for the production of arbolite blocks it is necessary to process wood in a special way (in rare cases, reed cutting 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

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 composition of the material contains exclusively natural raw materials;
light weight and large sizes of blocks, which simplifies construction and at the same time accelerates the pace of laying walls.

Sawdust concrete house

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

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

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

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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. Also, lime can be added as an additional binder, but there is no real need for its use. Cement mortar is an alkaline medium, when it enters sawdust, sugary substances are released from the sawdust, which adversely affect the final strength of the material.

To exclude negative processes, sawdust must be pre-treated. The easiest way to do this is to stand 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 soaking 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 manufactured material (the data in the table are indicated based on 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 moisture content of the material is 35-50%, then you need to add the maximum amount of water (350 l), ranging from 50 to 100% - the minimum amount.

The correct consistency of the solution

There are two sequences for mixing the solution:

Initially, cement is mixed with sand, after which sawdust is added to them and water is poured.
Sawdust is poured with water and cement is added, the mixture is stirred to a homogeneous consistency and sand is added.

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

An example of a homemade form for blocks

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

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

Drying blocks

It makes sense to make the form for 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 tamping the mixture. Also, the form should not have a bottom and side handles should be present. For ramming, a separate metal plate is made corresponding to the dimensions of the mold section.

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

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

Types of lightweight concrete

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

But in each of the groups there can be many varieties and compositions. Various aggregates and various binders are used. Traditionally, cements are used as a binder (on Portland cement, materials have better strength characteristics). The second most popular binder is lime, less often gypsum is used. Sometimes they can use a mixture of binders and use liquid glass.

Hardening technologies

There are three technologies for the manufacture of cellular concrete:

Placeholders

By 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. They have a closed pore structure, 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 wastes of some technological processes (slags) or materials specially created from natural components (expanded clay, vermiculite, perlite, etc.) as well as some chemical aggregates (polystyrene).

Properties, characteristics, application

The main characteristics of lightweight concrete that you should pay attention to when choosing are density (bulk weight), 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 over a wide range - from 500 to 1800, but most often it is in the range of 800-1500 kg / m 3. An exception is porous or cellular concrete (foam and aerated concrete). Their density can be from 200 kg/m 3 .

The main operational characteristic is compressive strength. It is subdivided into classes, indicated in the specification by the Latin letter "B", followed by numbers. These figures indicates the pressure that the material can withstand. For example, strength class B30 means that in most cases (according to GOST 95%) it can withstand a pressure of 30 MPa. But in the calculations they take a margin of safety of the order of 25%. And when calculating for class B30, a strength of 22.5-22.7 MPa is laid.

At the same time, such a characteristic as the compression limit is also 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 / m 3.

The thermal conductivity of lightweight concrete has an inverse relationship with respect to density: the more air a material contains, the less heat it conducts. This parameter varies considerably from 0.07 to 0.7 W/(mx°C). The lightest materials with low density are used as thermal insulation. They sheathe the walls of buildings and outbuildings. Foam concrete insulation of balconies and loggias is very popular. But the greatest economic effect can be obtained when building from lightweight medium-density concrete. It has sufficient bearing capacity to build a two- or three-story house. In this case, additional insulation is not required.

Table of thermal conductivity of lightweight concrete and traditional building materials

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

Purpose

By appointment, lightweight concrete is divided into the following groups:

Advantages and disadvantages

If we talk about the use of lightweight concrete as a heater, then there are few minuses. The main one is high hygroscopicity, which, nevertheless, varies over a wide range and strongly depends on the filler and the type of material. The second not very pleasant moment is the need to select the appropriate finish. If we are talking about exterior decoration (from the side of the street), then when choosing materials or type of decoration, it is necessary to take into account the high vapor conductivity. In this regard, either special vapor-permeable plasters are used or sheathing is made with a ventilation gap.

But the advantages of lightweight concrete as a heater are more significant. It is easy to install, lightweight, easy to cut and saw, tolerates weather changes well, does not require the use of wind protection. To all this, add high thermal insulation properties and a 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 in order to make an informed decision:

To increase the strength of the walls, frequent reinforcement is necessary. This is an additional cost for materials and time for laying reinforcement.
Insufficient crack resistance. 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, cobweb-like, they do not affect the strength of the structure, although they look intimidating.
High moisture absorption. The thermal insulation characteristics of wet materials are significantly reduced. Therefore, during construction, it is important to make high-quality waterproofing. If it is planned to use in conditions of 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 holds vertical loads well, but it is bad for pull-out. For lightweight and cellular concrete, special fasteners have been developed, but the best solution is to install mortgages in places where heavy objects are supposed to be fastened.
Difficulty in choosing exterior finishes. As already mentioned, this is either a cladding with a ventilated facade, or special plasters.
For interior decoration, a high-quality pre-primer 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 "tracks" passing between them, sounds are transmitted very well. For normal sound insulation, the use of additional materials is required.

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

Where and how to use at a construction site, do-it-yourself examples

As could be understood from all that has been said, lightweight concrete can be used for any structure. Walls are built from them, used as insulation, floor slabs are poured, and a screed is made. But all these tasks require different characteristics. They are "recruited" by the selection of components.

How to choose a recipe

For example, floor screed requires strength, hydrophobicity and low thermal conductivity. Strength and a decrease in the amount of absorbed moisture gives the use of Portland cement as a binder. Since the best natural additives that provide low moisture absorption - pumice and volcanic turf - cannot be called generally available, expanded clay or polystyrene balls can be used to increase thermal conductivity. They also absorb little moisture.

Now about proportions. They are taken standard for a given brand. And depending on the type chosen (sandless or normal), the aggregate is replaced. For floor screed, ordinary lightweight concrete is most often used. In them, the gravel is replaced with the selected aggregate, which is added in the desired proportion. Only water is taken less, 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 and density and other parameters. They make several small batches with different aggregate composition (large, small, their proportions, combine several different types of aggregate) and different amounts of water. After solidification, it is determined which one is best suited for a particular task. Using the same method, you can independently determine how much and what aggregate is better to pour, and then close large volumes.

An example of attic insulation with polystyrene concrete

See the video for an example of experimental selection for specific tasks. It was necessary to choose a composition for warming the attic floor. It was decided to use polystyrene concrete as warm and light. A sandless composition was chosen and only polystyrene balls were poured as a filler.

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

But this composition is only suitable for warming in places with a small load. If you need a screed with thermal insulation characteristics for 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 fibers, can be added. To improve plasticity, you can add, as in the video fragment, a certain amount of dish detergent 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. No news, except for a different composition: there is sand. The result is 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, balls are needed, and not any, but those that will adhere well to the solution. They have a strong film on the surface and do not absorb cement laitance, due to which they have good thermal insulation properties. The crumb obtained by grinding defective plates has an uneven and torn structure. As a result, it is impregnated with cement milk. Naturally, such concrete will be warmer than ordinary, but not the same as with granular.

Expanded clay concrete in private housing construction

Another popular aggregate for the production of lightweight concrete at home is expanded clay. It is made of clay, to which substances are added that increase in volume when heated. This composition is loaded into the furnace, where swelling takes place and followed by firing. But, as studies have shown, many clays are fonat, as a result, expanded clay also has a radiation background, sometimes even unsafe for health. So you need to be ready for his choice - to have a dosimeter.

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

Expanded clay concrete is used for pouring into molds and obtaining building blocks, and it is also possible to erect walls with adjustable formwork. Unlike expanded clay concrete blocks, this technology can be used to build 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 aggregate that costs mere pennies and can be used for private housing construction is sawdust, or rather shavings with sawdust. A very small 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 preserved: 6-7 parts of aggregate are taken for 1 part of concrete. In this case, sawdust. To increase the hydrophobicity of the composition, water glass or calcium chloride is added.

The second option of kneading and proportions

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Sometimes in construction it is required to reduce the load on the supporting structures. For example, a plank subfloor that needs to be leveled with concrete mortar for ceramic tiling. It is clear that the concrete layer has a sufficiently large weight, which the wooden structure may not withstand. In this case, experts recommend using lightweight concrete.

What it is?

This is a special type of concrete mixtures, in which porous materials are used as fillers: expanded clay, expanded perlite, foam balls and waste from various industries. It is these fillers that reduce the mass of the concrete itself, hence the name "light".

There is a certain classification of concrete solutions, one of the categories of which divides them by density (respectively, by mass). The density of lightweight concretes on porous aggregates is determined in the range from 500 to 1800 kg/m³ compared to conventional ones, which range from 2000 to 2500 kg/m³.

Properties of lightweight concrete

The main characteristics of the solution are as follows:

reduced density (mass);
convenience of construction work;
obtaining a more economical option by reducing the percentage of cement;
high strength material.

The subtleties of manufacturing

The most difficult thing in the preparation of lightweight concrete on porous aggregates is to correctly and accurately select the raw mix formulation, especially the water-cement balance. It is he who affects the strength of the material, its convenient use.

The thing is that porous fillers quickly absorb water into themselves, leaving practically no water for cement to set. Therefore, experts recommend that the selection of the recipe be carried out during the manufacture of the concrete solution itself.

Particular attention must be paid to the cement-water ratio, but the porosity of the filler will also have to be taken into account.

Recipe selection example

There are several options for selecting the density of lightweight concrete. One of them is the preparation of experimental closures.

Cement and fillers

For this, the standard recipe used for conventional concretes is taken. This is one volume of cement and six volumes of aggregate. If a combination of two or three types is used as fillers, for example, expanded clay and expanded perlite, then 4 parts are added to the large fraction (expanded clay), and 2 parts to the fine fraction (perlite).

Water

It is more difficult with water, here you will have to adjust its amount to the purpose of the concrete mixture. If the solution will be used for screeding, then it is better to make it liquid.

Checking blanks

Then, lightweight concrete is poured into a container, usually a cube. After drying, the workpiece is tested for strength. The same blanks will have to be made from solutions prepared according to other recipes. For example, you can increase the amount of expanded clay or, conversely, perlite, reducing the amount of cement introduced. In this case, you will have to increase the volume of water.

The strengths of all blanks are compared with each other. The indicator that fits the requirements of the structure to be poured is determined. But at the same time, the economic component must be taken into account. For example, from two suitable recipes, it is better to choose the cheapest composition.

Classification of mixtures

The classification of lightweight concrete mortars is based on the use in the composition of various fillers and the scope.

Simple Composition

Ordinary lightweight concrete is made according to the recipe described above. That is, it includes both large fillers and small ones. In this case, the volume of air between all materials should not exceed 6%.

Porosity

The composition may differ in the nature of porosity:

Sandless (large-pored) - the complete absence of fine filler. Air volume 25%.
Porous - obtained by adding materials that form pores to the cement mortar.

purpose

There is another kind of classification based on the purpose of lightweight concrete:

thermal insulation properties (density 500 kg / m³, thermal conductivity 0.25 W / m * K);
structural properties (density 1400-1800 kg / m³, strength M15, frost resistance not lower than F15);
structural and heat-insulating (density up to 1400 kg / m³, strength not less than M35, thermal conductivity - not more than 0.6).

The first group is used for pouring screeds, making heat-insulating plates. The second is used in load-bearing structures. The third is in self-supporting enclosing structures or in load-bearing ones.

Material consumption

As for the consumption of concrete mass, everything will depend on the type of filler used, on its porosity and quantity. But there is an average value - it is 200 kg per cubic meter. At the same time, the consumption of cement varies from 70 to 150 kg per cubic meter of concrete solution.

Manufacturing methods

Lightweight concretes on porous aggregates are prepared using different technologies, which depend on the type of additive.

Expanded Perlite Mix

Preparing lightweight concrete with your own hands is quite simple. First of all, perlite is wetted with water. It is a hygroscopic material, so it quickly absorbs it. Then 30% of the filler and the entire volume of cement are put into the concrete mixer. And this solution is thoroughly mixed.

Gradually, water is poured into it, into which plasticizers and modifiers were added in advance. Thorough mixing should cause the mixture to rise. This is a signal that you can start adding perlite residues to it. It is better to do this in small portions.

If the mortar is made by hand without using a concrete mixer, then it is better to do it in a clean bucket using a mixer or drill. It is possible with a shovel, but the uniformity of the components in the mixture may be low.

Often, fiber fibers are added to the mixture of concrete with perlite as a reinforcing composition. They must be introduced into the concrete when the main part of the filler is poured.

Composition with expanded clay

First, cement is thoroughly mixed with water until cement laitance forms on the surface. Please note that first, water is poured into the container (concrete mixer drum), then cement is poured in portions.

After that, expanded clay is introduced in portions. Here it is important, as in the first case, to achieve a uniform distribution of the components of the solution throughout the volume.

foam concrete

Making foam concrete with your own hands is not easy. This requires a foaming agent and a foam generator (special equipment that prepares foam). Let's just denote the production technology.
In a concrete mixer, a solution is prepared from sand and cement, where water is poured in a certain amount.

While the mixture is being prepared, a foaming agent is placed in the generator, which turns into foam inside the tank. With the help of a deposit, it is added to a semi-finished solution, where pore formation occurs. The foam is supplied by a pump.

What is lightweight concrete? In this case, the name does an excellent job of describing the material, the main differences of which are lighter weight, increased porosity and reduced thermal conductivity. But let's talk about everything in more detail.

General provisions

Concrete is reliability, durability, resistance to atmospheric phenomena, but not heat. The cement mortar has a high level of thermal conductivity and cannot provide an acceptable indicator of thermal insulation in the room.

For this reason, concrete houses are either subjected to additional insulation or require more heat carriers in winter. In any case, additional financial costs are required.

Methods for lowering the thermal conductivity of the solution itself were patented back in the middle of the last century. They consisted in increasing the porosity of the material due to special additives or the use of appropriate fillers. But at the same time, the strength of finished structures also decreased, which was unacceptable according to the GOSTs of that time.

The current price of energy resources, which has increased significantly in recent years, and the introduction of new production technologies that allow achieving higher strength qualities even with a low density condition, have given lightweight concrete a new life, raising it to the popularity pedestal.

All structural features of the material under consideration are determined according to GOST 25820 2000 and give them a lot of advantages:

Advantages

Low thermal conductivity. This is facilitated by a significant increase in porosity, which usually reaches forty percent of the total volume of the structure. In the table below, you can see the heat conduction coefficients for some types of lightweight concrete using different fillers, in comparison with classic bricks:

Little weight.

The lightness of this building material provides several additional advantages at once, making it possible to save on its use:

Ease of transportation.
No need to strengthen the foundation.
Ability to work at height without special lifting equipment.

High sound insulation. The porous fillers used perfectly prevent the movement of any sounds along the structure of the erected structure.
Versatility. Possibility of use both as a heater and as load-bearing walls.

Simple instruction manual.

There are a few things to note here:

Ready blocks have large convenient sizes.
In some cases, due to the precise geometry, it is allowed to use a special adhesive to fix the masonry elements instead of cement mortar, which allows you to hide the joints as much as possible.

Ease of processing. Due to the low density, they are easily sawn with an ordinary hacksaw, if necessary, shorten their dimensions, and there are also no problems with supplying all the necessary communications.

Possibility of making your own. Using the necessary fillers, and in some cases foaming agents, you can mix the solution you need at home.

Tip: in the case of organizing home production, it is recommended to use a concrete mixer. With its help, you can achieve the necessary uniformity and greatly speed up the process.

High frost resistance. This indicator determines the number of cycles of freezing and subsequent thawing without detrimental effects. In the case under consideration, depending on the binder used and the coarse aggregate, it can vary from F25 to F

Tip: to increase the frost resistance coefficient, you can always use the appropriate modifying additives. Their use can increase the number of transferred cycles up to 300, which will favorably affect the durability of the entire structure.

Long service life. With proper care, it can reach several decades.

Flaws

Increased porosity, which provides most of the benefits listed above, negatively affects some other parameters:

Decreased strength. It is due to the use of fillers less resistant to mechanical stress than in the case of heavy concretes.
Moisture absorption. Pores are channels for the penetration of liquid, the more of them, the higher the danger.

But today there are representatives of the lungs in order to play the role of load-bearing elements in a multi-storey building, and a non-hazardous level of hydrophobicity.

Features of the structure and varieties

From the general provisions, now let's move on to the specifics, since the types of properties for the use of lightweight concrete depend on the features of its structure and the filler used.

Structure

The classification of lightweight concrete according to their structure is as follows:

Ordinary. There is a classic concrete composition here: binder, fine aggregate, coarse aggregate and water. The air involvement in this case does not exceed six percent.
Coarsely porous. In such solutions, there is no sand during the mixing process, due to which the voids between the large components remain intact, and they themselves are covered with a thin layer of cement. This guarantees 25% air in the finished product.

Porous. The addition of a blowing agent to cement stimulates the formation of stuffy cells in it, due to which there is an increase in thermal insulation properties and a decrease in strength indicators.

Purpose

Depending on whether you are going to use lightweight concrete blocks only as insulation or intend to build load-bearing walls from them, a different approach to their production is used. To increase the strength indicators, a special autoclave treatment is performed. This allows the following classification of ready-to-use products:

Possible fillers

The composition of lightweight concrete differs depending on the coarse aggregate used to create it, which can be used as:

Natural. Produced by crushing and fractionating porous rocks.

These include:

pumice;
volcanic lava;
shell limestone.

Tip: the best choice from this group will be pumice due to the closed pore system, which significantly reduces the moisture-absorbing properties of the material.

Industrial waste without pre-treatment:

metallurgical slags;
fuel slag;
chemical sludge.

Industrial waste and stone materials that have undergone appropriate treatment:

Expanded clay. Granules of clay mass are expanded with the help of special additives, after which they are placed in an oven, where they are processed at a temperature of 1200 degrees Celsius. By the end of the forming process, an increase of 17 times occurs, which guarantees a very high porosity.

Aggloporite. It is made by sintering clay with processed coal residues.

Perlite. To get it, igneous polymineral rocks are heated to 1300 degrees Celsius, as a result of which they swell and form a material that looks like porous rubble.

Increased lightness

Light and extra light concretes can also be distinguished. Particularly light are those types of solutions in which no large filler is added, and porosity is realized by artificial foaming in the binder itself.

Such ultralight foam concrete has unique qualities:

Durability. It is not characterized by such harmful processes as rotting, corrosion and pest attacks.
Very low thermal conductivity, only 1 W/(m×0 C).
Environmental friendliness. The most environmentally friendly building material is wood, but foam concrete is in second place, and expanded clay concrete, for example, is in twentieth.
Simplicity and ease of installation. Absolutely correct shapes and low weight contribute to fast and high-quality construction work.

High fire resistance. With direct and prolonged exposure to flame, foam concrete does not split and does not explode, as can happen with heavy concrete.
Beautiful appearance. Taking into account the use of glue as a fixing agent, it can completely do without finishing work.

Low level of moisture absorption. The pores of this material are closed, which allows it to float on the surface of the water for a week. This allows him to endure any precipitation and severe frosts.

If you are wondering how to make the lightest of lightweight concretes, then information on the composition of the most versatile class D600 will come in handy:

Cement - 330 kg, grades not lower than M400.
Sand - 210 kg, preferably dry and cleaned.
Foaming agent - 1.1 kg.
Water - 180 liters.

Conclusion

Lightweight concrete perfectly combines low thermal conductivity and sufficiently high strength. Add to this economy, low weight, ease of operation, ease of processing and durability. As a result, we get an almost perfect building material that will allow you to build a reliable and comfortable home in the shortest possible time.

The video in this article will give you the opportunity to get acquainted with additional information that is directly related to the above materials. Use the most rational building materials when building your own home.

Everything is already created by nature. We can only use her tips in the development of high-tech materials. The developers of permeable concrete, which imitates natural soil, went this way.

Everything is already created by nature. We can only use her tips in the development of high-tech materials.

The developers of permeable concrete, which imitates natural soil, went this way. Permeable concrete is a highly porous material made of concrete particles glued together. The pore space occupies 15-25% of the total volume of the material. It turns out such a cheese with a lot of holes. High porosity provides 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. Rain water reaches the surface, is absorbed by the roots of plants, and the excess flows into the groundwater. Further, water evaporates through the leaves of plants and from the surface of reservoirs that are fed from groundwater. In cities where asphalt has literally "gobbled up" the entire surface, rainwater is discharged through drainage systems outside the city. As a result, the natural cycle is broken. Plants suffer from a lack of water, and groundwater does not receive the necessary nutrition. Permeable concrete, unlike asphalt, allows rainwater to pass through, which ensures 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 much lower than asphalt. Do not 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. Due to its porosity, unlike asphalt, it is resistant to temperature extremes. This eliminates the need for frequent road repairs, and in our reality, the annual re-laying of the asphalt pavement. Manufacturers of "miracle concrete" guarantee 15 years of operation in such conditions!

Aerated concrete is used in the US and Europe to build sidewalks, parking lots, highways, recreation area pavements, retaining walls, and slope reinforcement. Manufacturers are confident that over time, its scope will expand.

The developers of the Portuguese studio e-studio went even further. They "revived" the concrete by adding lawn grass seeds to it. 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, safely 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.