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 weight of concrete is reduced 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 (materials based on Portland cement 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 one performance characteristics — compressive strength. It is divided into classes, indicated in the specification 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, the strength is 22.5-22.7 MPa.

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 has an inverse relationship with 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 concrete medium density. It has sufficient load-bearing capacity 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 (from 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. This - 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 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. Special fasteners have been developed for lightweight and cellular concrete, but the best solution is the installation of mortgages in places where heavy objects are supposed to be attached.
• Difficulty in choosing exterior finishes. 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, floor screed requires 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 composition aggregate (large, fine, their proportions, combine several different types filler) and different quantities 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 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 essential 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 based on 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
At 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, and blind areas. 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 the gradual destruction of the concrete slab. For standard structures, concrete with plasticity P-2 or P-3 is used, for formwork complex shape 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 river sand without various impurities. If only ordinary fine sand is available, 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 when negative 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, reinforcing fibers are mixed into the concrete solution. 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 has its own meaning - the higher it is, the less water will be 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

There are several types of concrete mortar, which differ both in quality and proportional composition. The use of one or another solution option is determined individually, depending on the location of concreting. We will learn further about how to make concrete with your own hands.

How to make concrete with your own hands, proportions and technology

The most important component of concrete mortar is cement. Its function is to connect the other components with each other. Portland cement - ideal option for preparing concrete. This is explained by the fact that it contains large number calcium silicates. Thus, it is possible to achieve high adhesion between all components.

The type of cement used in the process of making concrete mortar is determined by the individual indicators of the scope of its application. Most often, grade 500 cement is used. Lower quality grades are used to prepare concrete for surfaces that are not subject to high loads.

Portland cement is used to improve adhesion between all components at both high and low temperatures. However, the minimum temperature for using concrete mortar is fifteen degrees. If concrete is still used at low temperatures, then its composition must contain special substances in the form of additives and plasticizers. The substance in the form of Portland slag cement is used if work is carried out at temperatures above 25 degrees Celsius.

The amount of impurities in the cement substance should not exceed twenty percent. This is indicated in the marking with the letter D. When choosing cement for the mortar, pay attention to its external indicators. It should be free-flowing and should not contain additional moisture. It is not recommended to buy material that has lumps and has a damp appearance.

Critical elements are built from concrete, which will quickly collapse due to poor quality cement. The material should also be stored in specially designated conditions, at a temperature of 10 degrees Celsius and a humidity not exceeding 60%. Cement easily absorbs moisture and odors from the external environment and quickly loses its positive characteristics. We recommend purchasing fresh cement that will be used within one or two weeks.

The second component of concrete mortar is sand. There are varieties of concrete solutions in which you can do without sand. This is only possible if the filler composition has no gaps or they are minimal.

The optimal sand fraction is from one to five millimeters. When choosing sand, give preference to materials that have sand grains of equal size. Sand should not contain clay or other impurities. The presence of remains of vegetation, stones, construction waste- negatively affects the quality of the resulting concrete solution.

If you have sand that is not very clean, we recommend sifting it several times before use. The best option- use of river sand, the cost of which is slightly higher than regular sand. However, such material does not have clay or foreign inclusions and has good performance characteristics.

The presence of clay in concrete is unacceptable; it negatively affects its strength and service life. The next point is to ensure maximum adhesion of concrete and coarse aggregate. These factors are the main ones in determining the overall strength of a concrete solution. In order to prepare the sand for work, we recommend washing it and leaving it to settle.

If it was not possible to purchase high-quality sand, then the option of using artificial sand is possible. To make it, rocks are finely crushed. This sand has greater density and weight. Please note that a concrete solution made from such sand will be heavy.

To increase the strength of the concrete solution, crushed stone or gravel is added to it. They act as a filler for concrete mortar. It is not recommended to use pebbles for these purposes, as their surface is smooth.

When choosing a filler, ask what type of litter it is made of. The expanded clay material is lightweight, but at the same time connects all the components well. The filler size ranges from 0.8 to 4 cm. It is recommended to choose medium-sized substances. It is recommended to choose a substance that does not contain dust and clay inclusions. The reliability of adhesion is determined by the roughness of the material.

Add a filler to the concrete solution that contains both large and medium particles. In this way, it is possible to achieve a tighter fit of the filler to the surface. Sand and filler should be located near the work site. In order to prevent contamination of sand or filler, we recommend pouring them onto a base previously covered with film.

The last of the main components of concrete mortar is water. It should not contain alkaline or acidic inclusions.

Substances in the form of:

1. Lime.

Using this material, the convenience of laying concrete mortar is increased. Thus, it is possible to improve the process of leveling the concrete solution. Lime reduces the strength of the mortar because the bond between cement and aggregates is reduced. Please note that lime in mandatory must be extinguished.

2. Plasticizers.

In order to do decorative concrete manually, it is recommended to use substances in the form of plasticizers. With their help it is possible to change quality characteristics solution.

3. Additional components.

With the help of certain components, the concrete solution becomes more progressive. In addition, by using additives it is possible to improve the setting of concrete mortar. Before using additives, study their characteristics and instructions for use. If the work of pouring concrete is carried out at low temperatures, then additives cannot be avoided.

4. Reinforcing components.

With the help of special additives it is possible to perform additional reinforcement of the concrete solution. For example, it is recommended to add fibers based on polypropylene or polyvinyl chloride to the concrete solution used to screed. These components are soft and especially durable. In this way, it is possible to achieve ideal smoothness of the concrete and prevent its cracking.

How to make foundation concrete by hand - composition proportions

The composition of concrete and the amount of connection of its components is determined by the purpose of using the concrete solution. For example, in order to build a foundation, you need strong concrete, which contains large crushed stone and a mortar that secures it securely.

At the same time, it is important to achieve fluidity of the solution, since it should not contain air bubbles or foreign inclusions. Before you start pouring the solution, it is recommended to make a substrate. To do this, it is enough to use a solution that is less durable in composition and contains inclusions of fine sand. At the same time, the consistency of the solution resembles wet soil.

The foundation mortar can be made using concrete by hand. At the same time, the filler should be medium in fractional size, and the consistency should be fluid. In this way, it is possible to distribute the solution on the surface. In addition, fine or medium fraction filler is used for the manufacture of flowerpots, garden elements, and concrete balusters.

The composition and quantity of components that the concrete solution contains are determined by SNiP. In this case, the density of each ingredient should be taken into account. We recommend using a medium-density concrete solution. After completing the calculations, proceed to connecting the components together.

The most popular component ratio involves using one part cement to three parts sand and six parts filler, with the amount of water varying from 0.4 to 1. Water makes the solution more or less fluid.

After determining the optimal consistency of the solution, you should measure the components. Please note that it is not recommended to use wet sand for work; it is recommended to dry it before adding it to the solution.

Before you make concrete steps with your own hands, you need to prepare a concrete solution. Most often, a concrete mixer is used for this. This device allows you to mix all ingredients evenly and quickly. The manual method of preparing concrete mortar is relevant only if the amount of work is small. At the same time, there is no possibility of controlling the recipe in this case.

There are two ways in which you can build a concrete solution yourself:

1. First, the dry ingredients are mixed together, and then water is added.

2. Sand, aggregate and cement are added to the water.

The first option is also called dry, in which all components are uniformly mixed together. In this case, water is added last. Sometimes, this composition contains dry lumps that reduce the strength of the solution. In order to avoid their appearance, we recommend using the second method of mixing the solution. It is suitable for mixing concrete in small quantities.

In any case, we still recommend using a concrete mixer to mix the solution. If you do not have this device, then rent it. The concrete mixer must be located near the work site. Thus, it is possible to avoid delamination of concrete during transportation.

A standard concrete mixer contains about two hundred liters of solution. This amount should be used as a guide when calculating the amount of ingredients. The process of preparing a solution in a concrete mixer is as follows:

1. Measure out the required amount of water and pour it into the concrete mixer. Do not fill in all the water, leave about 10% for later to bring the solution to the desired consistency.

2. Put cement in the required quantity, also leave some cement.

4. After cooking cement mortar If necessary, add substances to it in the form of additives and plasticizers.

5. At the final stage, filler is added. If the solution needs to add water, then it is mixed with cement, the resulting mixture is added to the concrete mixer at this stage.

All work is completed within 10-15 minutes. If it was not possible to extract the entire solution at one time, then it is constantly stirred until complete extraction.

How to make colored concrete with your own hands

Before making a concrete flowerpot with your own hands, we recommend painting the solution with color pigments. Modern technologies make it possible to make various concrete surfaces colorful and bright.

Pigments are added either at the stage of preparing the solution or after the composition has hardened. There are two options for color pigments:

• natural;
• synthetic.

The color palette and saturation are determined by the chemical components of the pigment. It is recommended to add pigment to the composition at the mixing stage. In this case, it is possible to achieve a uniform and beautiful color. In order to maximize the color effect on the surface, we recommend using sand and white cement when preparing the solution.

Before adding pigment, it is diluted with water. The quality of mixing affects the homogeneity of the solution. Moreover, such a composition is prepared exclusively in a concrete mixer. It is impossible to prepare concrete mortar manually.

Before making a concrete path with your own hands, it is also recommended to prepare a solution in a concrete mixer. This device not only saves time, but also significantly improves the quality of the finished solution.

When pouring concrete mortar, it is recommended to use a concrete vibrator. With its help, it is possible to remove air bubbles and improve the quality of the finished coating. Additional reinforcement is provided by steel reinforcement bars. Optimal time It takes about two days for the solution to set. Complete drying of the solution takes about two weeks or more.

Make concrete with your own hands video:

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 warm. Cement mortar has a high level of thermal conductivity and cannot provide an acceptable level of thermal insulation in a room.

For this reason concrete houses either undergo additional insulation or require greater coolant flow in winter time. In any case, additional financial costs are required.

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

The current price of energy resources, which has increased significantly over lately, and the introduction of new production technologies that make it possible to achieve higher strength properties even with low density conditions, have given lightweight concrete new life, placing him on the pedestal of popularity.

All structural features of the material in question are determined according to GOST 25820 2000 and endow them with a lot of advantages:

Advantages

1. 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 conductivity coefficients for some types of lightweight concrete using different fillers, in comparison with classic brick:

1. Light weight.

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

• Easy to transport.
• No need to strengthen the foundation.
• Possibility of carrying out high-altitude work without special lifting equipment.

1. High noise insulation. The porous fillers used perfectly prevent the movement of any sounds through the structure of the erected structure.
2. Versatility. Possibility of use both as insulation and as load-bearing walls.

1. Simple operating instructions.

A few points to note here:

• The finished blocks have large, convenient sizes.
• In some cases, due to the precise geometry, it is possible to use a special glue to fix masonry elements instead of cement mortar, which makes it possible to hide the joining seams as much as possible.

• Ease of processing. Easy to saw due to low density regular hacksaw if necessary, shorten their sizes; there are also no problems with supplying all the necessary communications.

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

Advice: in case of organization home production It is recommended to use a concrete mixer. With its help, you can achieve the necessary homogeneity and significantly speed up the process.

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

Advice: to increase the frost resistance coefficient, you can always use appropriate modifying additives. Their use can increase the number of transferable cycles to 300, which will have a beneficial effect on the durability of the entire structure.

1. Long service life. At proper care reaches several decades.

Flaws

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

1. Reduced strength. This is due to the use of fillers that are less resistant to mechanical stress than in the case of heavy concrete.
2. Moisture absorption. Pores are channels for liquid penetration; the more there are, the greater the danger.

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

Features of structure and varieties

From general provisions Now let's move on to specifics, since the types of properties of using lightweight concrete depend on the characteristics of its structure and the filler used.

Structure

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

1. Ordinary. Here you can see the classic concrete composition: binder, fine aggregate, coarse aggregate and water. Air entrainment in this case does not exceed six percent.
2. Large porous. In such solutions, there is no sand during the mixing process, due to which the voids between large components remain untouched, and they themselves are covered thin layer cement. This guarantees 25% air in the finished product.

1. Porized. Adding a pore-forming agent to cement stimulates the formation of stuffy cells in it, due to which the thermal insulation properties increase and the strength indicators decrease.

Purpose

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

Possible fillers

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

1. Natural. Produced by crushing and fractionating porous rocks.

These include:

• pumice;
• volcanic lava;
• limestone-shell rock.

Advice: best choice pumice will become from this group thanks to closed system pores, significantly reducing the moisture-absorbing properties of the material.

1. Industrial waste without pre-treatment:

• metallurgical slags;
• fuel slags;
• chemical slags.

1. Industrial waste and stone materials that have undergone appropriate processing:

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

• Agloporite. It is made by sintering clay with processed coal residues.

• Perlite. To obtain 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 crushed stone.

Increased lightness

You can also distinguish between light and extra-light concrete. Particularly light solutions include those types of solutions in which no coarse filler is added, and porosity is achieved through artificial foaming in the binder itself.

This ultra-light foam concrete has unique qualities:

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

1. High fire resistance. With direct and prolonged exposure to flame, foam concrete does not split or explode, as can happen with heavy concrete.
2. Beautiful appearance. Taking into account the use of glue as a fixing agent, finishing work can be completely dispensed with.

1. Low level of moisture absorption. Pores of this material closed, allowing it to float on the surface of the water for a week. This allows it to withstand any precipitation and severe frosts.

If you are wondering how to make the lightest of lightweight concrete, then you will need information about the composition of the most universal class D600:

1. Cement – ​​330 kg, grade not lower than M400.
2. Sand – 210 kg, preferably dry and cleaned.
3. Foaming agent – ​​1.1 kg.
4. Water – 180 l.

Conclusion

Lightweight concrete perfectly combines low thermal conductivity and fairly high strength. Let's add to this cost-effectiveness, low weight, ease of operation, ease of processing and durability. As a result, we will obtain an almost ideal 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 familiarize yourself with additional information that is directly related to the above materials. Use the most sustainable building materials when building your own home.

How to make strong concrete (concrete mortar) with your own hands.

Mortars and concretes are man-made stone materials that are produced by mixing a binder (usually lime and Portland cement) and certain aggregates. When mixed with water, the binder forms a stone-like body, which is explained by the processes of setting and rapid hardening. The strength of the stone-like body is ensured by the filler (gravel, crushed stone, sand). Next, I will tell you about all the stages of the question of how to make concrete with your own hands.

Components for making the solution

1. Filler

For mortar, most often, fine sand or other fine aggregate is taken. For concrete mortar, you can take not only fine sand, but also coarse gravel or crushed stone. To make construction plaster or masonry mortar, it is best to use fine sand, the grains of which do not exceed 2 millimeters in diameter. If the plaster has a special texture, it is possible to add sand with a grain size of up to 4 millimeters. In our market, customers are offered two types of sand: river and ravine. River sand is considered medium-grained, it is quite expensive, but its purity facilitates its use as a component for concrete mixture. Gully sand can be fine-grained (from 0.5 to 1.5 millimeters), with a large number of clay particles and other impurities. It is not suitable for good and strong concrete, but for mortars it can be used without fear.

For lean (light) cement concrete with strength class B7.5, only sand can be used as a filler. In concrete of greater strength, in addition to sand, you can also use crushed stone or gravel with a diameter of up to 31.5 millimeters. It is considered correct to use a crushed stone mixture of different fractions so that the finished concrete contains a minimum amount of voids between the stones.

Attention! The aggregate of concrete and mortars should not contain pollutants such as soil, glass, pieces of wood, peat, plants, dusty or silty soil. If contaminants are present, they should be removed by sifting gravel or sand through a sieve.

2. Cement

Cement is a general name for binding powdery substances based on marly, calcareous and clayey rocks and various additives. The most commonly used type of cement is Portland cement, which takes its name from the British peninsula of Portland. This cement contains a large amount of calcium silicates. Under construction country house Two types of Portland cement can be used.

Type I – does not contain additives, or their content does not exceed 5 percent. The European classification for such cement indicates the name CEM I.

In Russian practice, the presence of cement additives is indicated by the letter D and a number in the marking code, which follows the brand. For example, if you see the marking PC 500-D20, then it means the presence of 20 percent of additives in grade 500 Portland cement. As we have already found out, this characterizes type II cement. As for the DO designation, it characterizes type I cement, that is, a material without additives.

To prepare plaster and masonry mortar, you need to take cement of classes M400 (32.5) and M500 (42.5). Portland cement is ideal for preparing concrete mixtures that will be used at low temperatures (daily average below 10 degrees Celsius). If the temperature is high, for example, in the heat, then it is better to use slag Portland cement or type III cement (the European classification indicates the name CEM III). It is well suited for making masonry and plaster solutions, used for fences and floors.

Attention! Cement can only be purchased in bags with appropriate markings. Immediately before purchasing, you need to check whether the cement is damp or caked. If all the signs are present, it is recommended to refuse the purchase. Only a trusted, reputable manufacturer who has been selling the solution for several years can guarantee compliance with the brand of cement stated on the packaging or bag. By the way, the main difference good manufacturer What makes it underground is not the cost of ready-mixed concrete, but the availability of a high-quality delivery service.

3. Lime

Lime is required for the production of cement-lime mortars. In addition, it is used to increase the workability of the solution. Today, to prepare solutions, it is no longer necessary to slak lime. Instead, you can buy slaked (hydrated) fluffed lime at a low price, which is sold packaged in bags in ready-made form. Alternatively, instead of a dry mixture, lime can be sold in buckets in the form of lime paste. It is added to cement-lime plaster and masonry mortars to improve their workability.

Attention! If you decide to use lime as part of the question of how to make concrete at home, be extremely careful, since lime has strong corrosive properties. It is recommended to carry out work wearing protective gloves, remembering to ensure that the material does not get into your eyes or skin. The same applies to the use of dyes, as well as subsequent work on grinding and polishing the product.

4. Additives

The composition of a concrete mixture or mortar may contain certain additives that can either improve or simply change their certain properties.

Plasticizers or plasticizing additives can increase the fluidity of the mixture, as a result of which builders receive a solution with a more liquid consistency. This solution is much easier to apply.
Thinning additives or superplasticizers can reduce the amount of water poured for mixing.

In addition, their use makes it possible to improve the workability of the mixture, increase the strength, frost resistance and water resistance of the mortar or concrete.

Certain additives allow you to accelerate the hardening of a concrete mixture or solution.

Also, there are additives that make it possible to carry out work in the temperature range from 10 degrees below zero to 35 degrees hot.

There are special additives on the market that slow down the hardening of the concrete mixture, which is useful when concreting in hot conditions.

Air-entraining or aerating additives increase frost resistance and reduce the moisture capacity of the solution in the hardened state.

Typically, supplements are sold in plastic packaging in liquid form. The packaging must contain information about dosage, quantity and basic properties. Additives in mass ratio should not exceed 2 percent of the total mass of cement.

5. Water

The quality of water used for mortars and concretes is regulated by GOST standards. In particular, water must meet drinking standards and must not contain foreign impurities, including sugar, oil, alkalis and acids. It is prohibited to use poorly cleaned swamp and waste water. It is better to be guided by the principle that you can use any drinkable water to stir the solution. If you prepare a concrete solution using water from a lake or river, you will have to check the suitability of such water in a special construction laboratory.

Composition and proportions

Before you begin to consider the question of how to prepare concrete or reinforced concrete, I would like to draw your attention to the fact that the composition and proportions will directly depend on its main purpose. That is, it is correct to use strong concrete for the foundation high density, while for pouring the fence you can choose lighter grades. Once you have decided on the components, select the right brand. In most cases, for imported concrete and do-it-yourself mortars, it is better to choose grades M300 or M400. As for proportions, the components “cement/sand/crushed stone” should be used in proportions of 1/3/5. This means that per cube of concrete, one part of cement requires the addition of three parts of sand and five parts of crushed stone or gravel. If we talk about water, then its amount should be half the weight of other fillers. For example, if you have 100 kilograms of dry mixture, then you need to take 50 liters of water.

If you get too thick (dense) mixture, you can add a little more water. The consistency should be such that you do not need to exert much effort to stir the solution with a shovel. For wet sand there should be less water. If work is carried out in the cold, the water and concrete must be heated, which will protect the composition from premature setting and loss of strength. For work, it is better to use a purchased concrete mixer or devices/mixers and containers made by yourself. You can read what material and what components they consist of (pumps, molds, vibrating screeds, etc.) in another article.

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