Vitaly Lviv Currently, concrete and reinforced concrete are the basic building materials. In our country, producing tens of millions of tons of concrete and mortar. Not one house built in the last 60 years is not without concrete products. Therefore the subject of concrete and reinforced concrete is today very important. It is important to know not only the production technology, but to be able to reduce costs. Speaking of concrete, we must not forget the reinforced concrete. Because of his exceptional qualities, it is widely used in modern construction. Reinforced concrete - a concrete, in which steel bars are introduced - and fittings. The word "fixture" - the Italian word in Russian means "arms". Why it took "arm" or, as experts say, "reinforced" concrete? In building on the constructions are compression and tension, under whose influence the design of warp. Very clearly we can represent the two forces, if we take an ordinary rubber band, put it on two pillars, and click on it in the middle of the eraser will shrink at the top, but the stretch at the bottom. In the middle part of the same length of gum will not change. Is the conventional line that divides the gum in two parts - the compressed and stretched, called the neutral axis. When operating a concrete structure in bending is obtained by a similar pattern of deformation. Since the strength of concrete in tension is low, concrete structures under bending collapse at very low load. Strength as a steel rod in tension at 100 - 200 times higher than that of concrete. Hence, if we make both materials (concrete and steel) to work as a whole, ie, to achieve the same strength in the compression zone and tension zone of a flexible concrete structure, it can be increased by several times the strength of structures in bending. For this purpose, the stretched part introduces several steel rods (rebar) of a particular section. Now concrete structure does not break when bent and can withstand many times the failure load. How then can work together in one design, two such dissimilar materials such as concrete and steel? It turns out that help their properties: high compressive strength, high strength reinforcing steel in tension, a large bonding strength of concrete and steel, almost the same length change of concrete and steel when the temperature changes. Thanks to interlocking concrete reinforcement, it can not pull out of concrete. When hardening of the concrete shrinks and compresses the valve, and thus even stronger adhesion to it. Bonding strength of concrete with reinforcement will increase with time and the larger, denser concrete and more reinforcement surface roughness. Relatively low thermal conductivity of concrete have been very useful for concrete structures: concrete protects the steel rebar from sudden temperature changes. Reinforced concrete as a building material has appeared only in the middle of the XIX century, but already widely used in all areas of construction. Reinforced concrete structures combine high strength, lightness and grace. As an example we can take a very nice two-story Metro Bridge in the Luzhniki Stadium. Concrete - artificial stone material, obtained by curing a specially prepared mixture consisting of a large binder and fine aggregate and water. If necessary, the concrete mixture is introduced special additives to improve its technological and structural characteristics. The composition of the concrete mix should provide a definite date specified properties (strength, frost resistance, water resistance, etc.) Concrete is the main construction material, which is used in all areas of construction. Techno-economic benefits of concrete and reinforced concrete are: low cost manufacturing structure in connection with the use of local raw materials, the possibility of using a modular and monolithic constructions of various types and purposes, the mechanization and automation of production and preparation of concrete structures. Concrete mix with proper treatment can make design the optimal form in terms of structural mechanics and architecture. Concrete is durable and fire-resistant, its density, strength and other characteristics can vary widely. The disadvantage of concrete, as any rock material is the low tensile strength, which is 10-15 times lower than the compressive strength. This disadvantage is eliminated in the concrete, when the tensile stress takes the valves. Due to these major advantages concretes of various types and reinforced concrete structures are the foundation of modern construction. By type of binder concretes are divided into: cement (most common), silicate (lime-siliceous), plaster, mixed (cement-lime, lime-slag, etc.), and others - are used in special requirements (heat resistance, chemical resistance, etc.). By type of aggregate concretes are distinguished by: dense, porous, special aggregates satisfying the special demands (protection against radiation, heat resistance, chemical resistance, etc.). In the form of aggregates used local stone materials: sand, gravel, rubble, and the byproducts of industry. Types of concrete, depending on the density of concrete are distinguished: very heavy - weighing more than 2500 kg/m3, manufactured by the most severe of the filler (of magnetite, barite, iron scrap, etc.) They are used for special protective structures; heavy - a density of 2200-2500 kg/m3 in the sand, gravel or crushed stone from the rock, used in all load-bearing structures, lightweight - a density of 1800-2200 kg/m3; they are used mainly in the load-bearing structures; lungs - a density of 500-1800 kg/m3, these include : a) lightweight concrete on porous natural and synthetic fillers, and b) cellular concrete (aerated and foam concrete) of a mixture of binder, water, fine-grained siliceous component and porodoobrazovatelya c) krunoporistye (bespeschanye) concrete on dense or porous coarse aggregate - no fines . Particularly lightweight concrete (cellular and porous aggregates) - density of less than 500 kg/m3; used as izolyatsii.Legkie concrete thermal conductivity less than heavy, so they are used mainly in outdoor enclosure designs. In load-bearing structures using more dense and durable lightweight concrete (on the porous aggregates and cellular) density 1200-1800 kg/m3. In the design of concrete and reinforced concrete structures designate the desired characteristics: class (brand) of concrete strength, frost resistance and impermeability grade. Concrete must be uniform - it's the most important technical and economic requirements. Concrete is in need of care, to create normal conditions of hardening, particularly in the initial period after installation (up to 15-28 days). During warmer months, the moisture in the concrete store by watering and shelter. On the surface of fresh concrete is applied bitumen emulsion or a shelter, and other plastic films. In the manufacture of concrete and concrete products and structures to improve their reliability and safety of conducting static control and acceptance on the strength, taking into account the actual uniformity. Calculated characteristics of homogeneity and strength are used to control production within the so-called controlled periods, which is also a month. Aerated Concrete Not all vague about the difference between "aerated," "cellular concrete" and "cellular concrete". What is it - three different materials or the same? It turns out that no one and no more. Of all these concepts and the main key is the "cellular concrete". So we call a whole group of materials having similar properties. Porous concrete is called artificial lightweight concrete material number of inorganic compounds, the basic structural element in - air (40 to 95?% By volume). It is produced as a result of solidification expanded with blowing agent mixture of binder, siliceous component and water. If swelling of the initial mixture forms a characteristic "cellular" structure of concrete with evenly distributed in terms of air pores, making cellular concrete has a low density and low thermal conductivity. The porosity of porous concrete is relatively easy to adjust in the manufacturing process, the result is a concrete of different densities and destination. Cellular concrete belong to the class of lightweight concrete. Single classification has not yet worked out, the distinctive features include a variety of ways to obtain a porous structure, the types of binder, the conditions of molding, curing, etc. In the Soviet Union introduced the concept of "cellular concrete", the main feature of which is a method of forming a porous structure, which gives closed cells filled with air. Thus, according to the classification of GOST 25485-89 cellular concrete is divided into two groups. The first group. Concretes obtained using gazoobrazovatelya followed by autoclaving. The material hardens at high temperature and high pressure in a special oven - autoclave. Swelling test binder by chemical means, when it injected substance (gas generating agent) and a mixture of chemical reactions accompanied by gas emission. These concretes produced in large factories and the construction site they come in the form of pre-engineered. Produce such material on a small production impossible. The strength of aerated concrete gains, as already mentioned, in the autoclave in its production must be controlled at the same time dozens of processes. Working with this material is similar to working with a brick. Autoclaved aerated concrete is currently under the name of aerated concrete produced many varieties of lightweight concrete. They differ in the composition of the fillers, but the principle of production and the structure they have one: they all resemble the aerated chocolate. True quality of a different, like different kinds of chocolate. Aerated concrete - this is an easy man-made material obtained as a result of hardening of porous mixture that includes sand, water, lime, cement, aluminum powder and gypsum. Enclosed in the pores of the air helps create insulation effect. The porous structure ensures that the heat in the winter and in summer a pleasant coolness. Porous concrete is not only good at trapping heat, but also perfectly protected from the noise. Cellular concrete is also "breathes". Not to interfere with this ability it should bear its vapor-permeable plaster and paint. This feature of cellular concrete must be taken into consideration when building a house made of cellular concrete. Cellular concrete blocks are well handled by the simplest tools - saw, lattice, drilling, toothing. Easy to handle it possible to produce designs of different configurations (including the arch). Cellular concrete blocks have a closed internal pores, so it does not absorb moisture. In addition, it is not lit, and its properties (as opposed to, for example, from bricks) is not particularly limited in temperatures typical of household fires. Block sizes are produced on the line of aerated concrete, are L = 600 mm, H = 250 mm, the width ranges from 100 to 400 mm. The density of units ranging from 100-700 kg/m3. Small volume weight reduces transportation and installation costs. When masonry walls block size 600h250h200 mm has a weight of 15 kg in the dry state (at 500 kg / m 3) and replaces the conventional 18-20 clay bricks weighing about 80 kg. Another important property of porous concrete, which we can not say - is ecologically clean. All source components are checked for the absence of radioactive and carcinogenic substances, heavy metal impurities whose concentrations must not exceed the MPC. At a rate of environmental cellular concrete is second only to the tree. Tips: - must be observed during construction of the building, the requirements stipulated in the project. - Walls made of porous concrete blocks, adjacent to which either a horizontal or sloping surface canopies, roofs, additions should be protected with waterproof coating to a height of not less than 500 mm. - It is necessary that all the sill of the openings were plum out of the plane walls by not less than 50 mm. - The most common mistake is no gap between the facing bricks and blocks. In this case, penetrating into the wall of the residential water vapor does not come out. Characteristics of cellular concrete is now widely wear industrial buildings of enterprises and residential buildings reached a critical level, the issues of economical and reliable reconstruction of the facades, roofs of office and apartment buildings are becoming increasingly acute. The use of non-autoclaved aerated concrete, monolithic, growing, water-resistant can cost-effectively strengthen the chassis and the facades of buildings, greatly increasing their life, without the annual "cosmetic" repairs. This material is almost twice easier keramsit has low density sufficiently high strength (3,0-6,0 MPa). High thermal insulation is achieved thanks to the special porous structure: the wall of a porous non-autoclaved monolith thickness 350 mm corresponds to the thermal insulation of brick in 1200 mm. Frost resistance of porous concrete - for more than 75 cycles of laboratory data and more than 200 cycles of calculation. Non-autoclaved porous monolith is not afraid of moisture and does not collapse in a wet environment. Water absorption, water absorption is almost equal to conventional concrete and decreases with increasing density. Aerated concrete can be successfully used in the construction of swimming pools: tile laid directly on the growing mass, which provides 100% traction with the base tile. By the obvious advantages of the material should also include good sound-absorbing and insulating properties of the material (for walls 100 mm - 36 dB for 150 mm - 55 dB), fire and environmental safety. The porous structure gives the effect of a kind of "sonic labyrinth" in the audible band 63 ... 8000 Hz. Good adhesion to concrete, metal and wood, a high sealed seams process makes it possible to create light-weight sound-absorbing, reflecting the layered structure of different materials such as sandwiches. Non-autoclaved aerated concrete, solid, growing, water-resistant easy to process and significantly reduces the cost of producing and manufacturing operations. The totality of these properties and characteristics enables a wide application in construction. Applying the porous monolith can be quickly and accurately carry out works to restore and repair the walls of buildings without dismantling the enclosure wall panels, foundations, basement, facades and floors. The technology is simple: a liquid solution of porous monolithic non-autoclave cellular concrete is poured into the formwork, where it fills all the voids and cracks, and expands thereby securely seal and restore the ruined foundation and wall stones. Preparation of the solution takes 10 minutes at zero temperature and requires the use of only 3 ingredients: water, cement and specially balanced powdered blowing agent. Note that the technology allows us to use this material in a complex, curvilinear architectural, artistic and sculptural solutions. Non-autoclaved aerated concrete, solid, growing, water-resistant was used in the construction of several apartment houses in Yekaterinburg, the economic effect of 34%. There is a positive experience using this material in the construction of building facades, which thus acquires an additional architectural expressiveness (the surface of a "crushed stone", etc.). You can restore the wooden facades, which will become the new "face", and protection from access to oxygen and water slows the processes of decay of wood. This property is especially important when restoring monuments. The use of non-autoclaved aerated concrete, monolithic, growing, water-resistant increases longevity and quality of light roof, especially with the use of cold bituminous paste. Samorastuschy effect of the solution leads to the sealing of even small flaws in the basis of the roof, resulting in a strong uniform coating with tight adjunction to technological designs of the roof. Stacking is cold with high mechanization, which greatly reduces the time and reduces the cost of the work.
Vitaly Lviv Currently, concrete and reinforced concrete are the basic building materials. In our country, producing tens of millions of tons of concrete and mortar. Not one house built in the last 60 years is not without concrete products. Therefore the subject of concrete and reinforced concrete is today very important. It is important to know not only the production technology, but to be able to reduce costs. Speaking of concrete, we must not forget the reinforced concrete. Because of his exceptional qualities, it is widely used in modern construction. Reinforced concrete - a concrete, in which steel bars are introduced - and fittings. The word "fixture" - the Italian word in Russian means "arms". Why it took "arm" or, as experts say, "reinforced" concrete? In building on the constructions are compression and tension, under whose influence the design of warp. Very clearly we can represent the two forces, if we take an ordinary rubber band, put it on two pillars, and click on it in the middle of the eraser will shrink at the top, but the stretch at the bottom. In the middle part of the same length of gum will not change. Is the conventional line that divides the gum in two parts - the compressed and stretched, called the neutral axis. When operating a concrete structure in bending is obtained by a similar pattern of deformation. Since the strength of concrete in tension is low, concrete structures under bending collapse at very low load. Strength as a steel rod in tension at 100 - 200 times higher than that of concrete. Hence, if we make both materials (concrete and steel) to work as a whole, ie, to achieve the same strength in the compression zone and tension zone of a flexible concrete structure, it can be increased by several times the strength of structures in bending. For this purpose, the stretched part introduces several steel rods (rebar) of a particular section. Now concrete structure does not break when bent and can withstand many times the failure load. How then can work together in one design, two such dissimilar materials such as concrete and steel? It turns out that help their properties: high compressive strength, high strength reinforcing steel in tension, a large bonding strength of concrete and steel, almost the same length change of concrete and steel when the temperature changes. Thanks to interlocking concrete reinforcement, it can not pull out of concrete. When hardening of the concrete shrinks and compresses the valve, and thus even stronger adhesion to it. Bonding strength of concrete with reinforcement will increase with time and the larger, denser concrete and more reinforcement surface roughness. Relatively low thermal conductivity of concrete have been very useful for concrete structures: concrete protects the steel rebar from sudden temperature changes. Reinforced concrete as a building material has appeared only in the middle of the XIX century, but already widely used in all areas of construction. Reinforced concrete structures combine high strength, lightness and grace. As an example we can take a very nice two-story Metro Bridge in the Luzhniki Stadium. Concrete - artificial stone material, obtained by curing a specially prepared mixture consisting of a large binder and fine aggregate and water. If necessary, the concrete mixture is introduced special additives to improve its technological and structural characteristics. The composition of the concrete mix should provide a definite date specified properties (strength, frost resistance, water resistance, etc.) Concrete is the main construction material, which is used in all areas of construction. Techno-economic benefits of concrete and reinforced concrete are: low cost manufacturing structure in connection with the use of local raw materials, the possibility of using a modular and monolithic constructions of various types and purposes, the mechanization and automation of production and preparation of concrete structures. Concrete mix with proper treatment can make design the optimal form in terms of structural mechanics and architecture. Concrete is durable and fire-resistant, its density, strength and other characteristics can vary widely. The disadvantage of concrete, as any rock material is the low tensile strength, which is 10-15 times lower than the compressive strength. This disadvantage is eliminated in the concrete, when the tensile stress takes the valves. Due to these major advantages concretes of various types and reinforced concrete structures are the foundation of modern construction. By type of binder concretes are divided into: cement (most common), silicate (lime-siliceous), plaster, mixed (cement-lime, lime-slag, etc.), and others - are used in special requirements (heat resistance, chemical resistance, etc.). By type of aggregate concretes are distinguished by: dense, porous, special aggregates satisfying the special demands (protection against radiation, heat resistance, chemical resistance, etc.). In the form of aggregates used local stone materials: sand, gravel, rubble, and the byproducts of industry. Types of concrete, depending on the density of concrete are distinguished: very heavy - weighing more than 2500 kg/m3, manufactured by the most severe of the filler (of magnetite, barite, iron scrap, etc.) They are used for special protective structures; heavy - a density of 2200-2500 kg/m3 in the sand, gravel or crushed stone from the rock, used in all load-bearing structures, lightweight - a density of 1800-2200 kg/m3; they are used mainly in the load-bearing structures; lungs - a density of 500-1800 kg/m3, these include : a) lightweight concrete on porous natural and synthetic fillers, and b) cellular concrete (aerated and foam concrete) of a mixture of binder, water, fine-grained siliceous component and porodoobrazovatelya c) krunoporistye (bespeschanye) concrete on dense or porous coarse aggregate - no fines . Particularly lightweight concrete (cellular and porous aggregates) - density of less than 500 kg/m3; used as izolyatsii.Legkie concrete thermal conductivity less than heavy, so they are used mainly in outdoor enclosure designs. In load-bearing structures using more dense and durable lightweight concrete (on the porous aggregates and cellular) density 1200-1800 kg/m3. In the design of concrete and reinforced concrete structures designate the desired characteristics: class (brand) of concrete strength, frost resistance and impermeability grade. Concrete must be uniform - it's the most important technical and economic requirements. Concrete is in need of care, to create normal conditions of hardening, particularly in the initial period after installation (up to 15-28 days). During warmer months, the moisture in the concrete store by watering and shelter. On the surface of fresh concrete is applied bitumen emulsion or a shelter, and other plastic films. In the manufacture of concrete and concrete products and structures to improve their reliability and safety of conducting static control and acceptance on the strength, taking into account the actual uniformity. Calculated characteristics of homogeneity and strength are used to control production within the so-called controlled periods, which is also a month. Aerated Concrete Not all vague about the difference between "aerated," "cellular concrete" and "cellular concrete". What is it - three different materials or the same? It turns out that no one and no more. Of all these concepts and the main key is the "cellular concrete". So we call a whole group of materials having similar properties. Porous concrete is called artificial lightweight concrete material number of inorganic compounds, the basic structural element in - air (40 to 95?% By volume). It is produced as a result of solidification expanded with blowing agent mixture of binder, siliceous component and water. If swelling of the initial mixture forms a characteristic "cellular" structure of concrete with evenly distributed in terms of air pores, making cellular concrete has a low density and low thermal conductivity. The porosity of porous concrete is relatively easy to adjust in the manufacturing process, the result is a concrete of different densities and destination. Cellular concrete belong to the class of lightweight concrete. Single classification has not yet worked out, the distinctive features include a variety of ways to obtain a porous structure, the types of binder, the conditions of molding, curing, etc. In the Soviet Union introduced the concept of "cellular concrete", the main feature of which is a method of forming a porous structure, which gives closed cells filled with air. Thus, according to the classification of GOST 25485-89 cellular concrete is divided into two groups. The first group. Concretes obtained using gazoobrazovatelya followed by autoclaving. The material hardens at high temperature and high pressure in a special oven - autoclave. Swelling test binder by chemical means, when it injected substance (gas generating agent) and a mixture of chemical reactions accompanied by gas emission. These concretes produced in large factories and the construction site they come in the form of pre-engineered. Produce such material on a small production impossible. The strength of aerated concrete gains, as already mentioned, in the autoclave in its production must be controlled at the same time dozens of processes. Working with this material is similar to working with a brick. Autoclaved aerated concrete is currently under the name of aerated concrete produced many varieties of lightweight concrete. They differ in the composition of the fillers, but the principle of production and the structure they have one: they all resemble the aerated chocolate. True quality of a different, like different kinds of chocolate. Aerated concrete - this is an easy man-made material obtained as a result of hardening of porous mixture that includes sand, water, lime, cement, aluminum powder and gypsum. Enclosed in the pores of the air helps create insulation effect. The porous structure ensures that the heat in the winter and in summer a pleasant coolness. Porous concrete is not only good at trapping heat, but also perfectly protected from the noise. Cellular concrete is also "breathes". Not to interfere with this ability it should bear its vapor-permeable plaster and paint. This feature of cellular concrete must be taken into consideration when building a house made of cellular concrete. Cellular concrete blocks are well handled by the simplest tools - saw, lattice, drilling, toothing. Easy to handle it possible to produce designs of different configurations (including the arch). Cellular concrete blocks have a closed internal pores, so it does not absorb moisture. In addition, it is not lit, and its properties (as opposed to, for example, from bricks) is not particularly limited in temperatures typical of household fires. Block sizes are produced on the line of aerated concrete, are L = 600 mm, H = 250 mm, the width ranges from 100 to 400 mm. The density of units ranging from 100-700 kg/m3. Small volume weight reduces transportation and installation costs. When masonry walls block size 600h250h200 mm has a weight of 15 kg in the dry state (at 500 kg / m 3) and replaces the conventional 18-20 clay bricks weighing about 80 kg. Another important property of porous concrete, which we can not say - is ecologically clean. All source components are checked for the absence of radioactive and carcinogenic substances, heavy metal impurities whose concentrations must not exceed the MPC. At a rate of environmental cellular concrete is second only to the tree. Tips: - must be observed during construction of the building, the requirements stipulated in the project. - Walls made of porous concrete blocks, adjacent to which either a horizontal or sloping surface canopies, roofs, additions should be protected with waterproof coating to a height of not less than 500 mm. - It is necessary that all the sill of the openings were plum out of the plane walls by not less than 50 mm. - The most common mistake is no gap between the facing bricks and blocks. In this case, penetrating into the wall of the residential water vapor does not come out. Characteristics of cellular concrete is now widely wear industrial buildings of enterprises and residential buildings reached a critical level, the issues of economical and reliable reconstruction of the facades, roofs of office and apartment buildings are becoming increasingly acute. The use of non-autoclaved aerated concrete, monolithic, growing, water-resistant can cost-effectively strengthen the chassis and the facades of buildings, greatly increasing their life, without the annual "cosmetic" repairs. This material is almost twice easier keramsit has low density sufficiently high strength (3,0-6,0 MPa). High thermal insulation is achieved thanks to the special porous structure: the wall of a porous non-autoclaved monolith thickness 350 mm corresponds to the thermal insulation of brick in 1200 mm. Frost resistance of porous concrete - for more than 75 cycles of laboratory data and more than 200 cycles of calculation. Non-autoclaved porous monolith is not afraid of moisture and does not collapse in a wet environment. Water absorption, water absorption is almost equal to conventional concrete and decreases with increasing density. Aerated concrete can be successfully used in the construction of swimming pools: tile laid directly on the growing mass, which provides 100% traction with the base tile. By the obvious advantages of the material should also include good sound-absorbing and insulating properties of the material (for walls 100 mm - 36 dB for 150 mm - 55 dB), fire and environmental safety. The porous structure gives the effect of a kind of "sonic labyrinth" in the audible band 63 ... 8000 Hz. Good adhesion to concrete, metal and wood, a high sealed seams process makes it possible to create light-weight sound-absorbing, reflecting the layered structure of different materials such as sandwiches. Non-autoclaved aerated concrete, solid, growing, water-resistant easy to process and significantly reduces the cost of producing and manufacturing operations. The totality of these properties and characteristics enables a wide application in construction. Applying the porous monolith can be quickly and accurately carry out works to restore and repair the walls of buildings without dismantling the enclosure wall panels, foundations, basement, facades and floors. The technology is simple: a liquid solution of porous monolithic non-autoclave cellular concrete is poured into the formwork, where it fills all the voids and cracks, and expands thereby securely seal and restore the ruined foundation and wall stones. Preparation of the solution takes 10 minutes at zero temperature and requires the use of only 3 ingredients: water, cement and specially balanced powdered blowing agent. Note that the technology allows us to use this material in a complex, curvilinear architectural, artistic and sculptural solutions. Non-autoclaved aerated concrete, solid, growing, water-resistant was used in the construction of several apartment houses in Yekaterinburg, the economic effect of 34%. There is a positive experience using this material in the construction of building facades, which thus acquires an additional architectural expressiveness (the surface of a "crushed stone", etc.). You can restore the wooden facades, which will become the new "face", and protection from access to oxygen and water slows the processes of decay of wood. This property is especially important when restoring monuments. The use of non-autoclaved aerated concrete, monolithic, growing, water-resistant increases longevity and quality of light roof, especially with the use of cold bituminous paste. Samorastuschy effect of the solution leads to the sealing of even small flaws in the basis of the roof, resulting in a strong uniform coating with tight adjunction to technological designs of the roof. Stacking is cold with high mechanization, which greatly reduces the time and reduces the cost of the work. Guaranteed service life of such a roof is 20-25 years, without intermediate repairs and without changing the properties of the coating. Heat and sound insulation properties of this material is widely used in screed floors, sealing the joints overlap. Its use in the construction of a 17-storey building of the Ural Control Center rail allowed us to obtain economic benefit to the average of 50%. Properties of cellular concrete strength and density are the main indicators of the quality of aerated concrete. Density, fluctuating from 300 to 1200 kg / cubic meter. m, indirectly characterizes the porosity of the material (85-60%, respectively). Established the following brands of cellular concrete for compressive strength: M15, M25, M35, M50, M75, M100, M150. Classes on the compressive strength are within in the 0,35 - 12,5. Water absorption and frost resistance depend on the magnitude and nature of the porosity and density of aerated concrete walls between macropores (cell). To reduce water absorption and frost tend to increase the capacity of a cellular structure with closed pores. This is facilitated by vibrating technology, right? As vibration porous concrete mixture destroyed large cell, reducing frost and homogeneity of the material. There are the following brands of cellular concrete by frost: F15, F25, F35, F50, F75, F100. For exterior wall panels used cellular concrete stamps F15, F25, depending on the humidity of the atmosphere in the rooms and climatic conditions. Higher frost resistance is required of structural cellular concrete, subjected to multiple freezing and thawing. The thermal conductivity of porous concrete depends on the density and moisture content, such as the density of 600 kg / cu. m the thermal conductivity in a dry condition 0.14 W / (m · ° C) with humidity of 8% - 0,22 W / (m · ° C). Shrinkage depends on the composition of the material, density, and hardening conditions. Porous concrete density of 700 800 kg / cu. m in air with relative humidity of 70-80% and a temperature of 20 ° C has a shrinkage of 0,4-0,6 mm / m. The equipment for the production of non-autoclaved aerated concrete, solid, growing, water-resistant provides great opportunities for rapid monolithic building cheap houses in height 3 floors. Smooth, smooth walls, built on this technology, once ready for painting or wallpaper, do not require additional finishing. In the case of manufacture of blocks of cellular concrete for cast-in frame structures on site reduces the nomenclature of necessary construction materials, transport costs are significantly reduced. Equipment for the production of non-autoclaved aerated concrete, reinforced growing up, waterproof mortar consists of high capacity from 0.1 m3 to 2.0 m3. Setting a volume of 1 m3 weighs only 100 kg in size takes place in all the doorways and prevents a solution with a dry poroobrazuyuschei mixture for 13 seconds. Performance of such a facility, on average - 24 m3 per shift. Equipment for high-performance, easily transportable to any floor by hand. At present, the mass production of cellular concrete in the advanced enterprises of the country achieved the indicators relevant to the world level. It should be said that the density of building blocks of cellular concrete 400 kg / m 3 is critical, because even with lower density and lower thermal conductivity is achieved, but at the same time greatly reduced strength, and, especially, frost. As experience has shown the design, the optimal ratio between the density of aerated concrete, on the one hand, and his strength and frost - the other is in the range 400-600 kg/m3. In this case, porous concrete blocks can be used in load-bearing exterior walls of buildings of low and medium (4-5), number of floors, as well as in non-bearing exterior walls of tall buildings, subject to acceptable for structural and economic reasons, the thickness of the walls. In some cases, cellular concrete in the construction of exterior walls can be successfully combined with brick veneer and effective insulation. I should say that, as will be shown below, single-layer porous wall are the most cost-effective for reduced costs. Should also be noted that the increase in the density of cellular concrete in the event of factory technology, does not guarantee a corresponding increase in frost resistance, especially in the density range 400-550 kg/m3. In recent years, in connection with the establishment of an effective foam becoming more common non-autoclave foam, which is due to the desire to simplify the manufacture of this material, to reduce the energy used to produce and be able to apply it in a construction site. Foam autoclaving have almost the same physical and mechanical properties as concrete, but the shrinkage caused by insufficient stability of the foam. Foam is non-autoclave processing in mass production have not yet reached the quality of AAC, although at the level of pilot or limited production, they, according to some developers already comply with aerated. The use of cellular concrete Cellular concrete is an effective modern materials for construction work. AAC and non-autoclaved aerated concrete - the main varieties of cellular concrete in production technology, they are interchangeable, and meet the requirements of the general state standard. The most massive use of cellular concrete received in the manufacture of lightweight concrete structures, and insulation. Of them are widespread structurally insulation. They are used for exterior wall panels and coverings of buildings, unreinforced wall and insulation blocks, stones for walls. Design of cellular concrete durability in buildings with a normal mode space, with a relative humidity of 60-70?%. Wall materials from them - it's quality, environmentally friendly and cheap construction products, modern alternative to traditional brick, dense block, natural porous stone. Need to pay special attention to one of the important characteristics of the material - its relatively low breaking strength. If the tree is able to withstand some movement framework, the stone and, in particular, cellular concrete in such a case will instantly crack. Therefore, when constructing the building of cellular concrete should erect monolithic strip foundations or basement of an ordinary heavy concrete or reinforced cellular concrete with a special waterproofing, which entails considerable expense. Make a powerful and expensive for a small home based profitable due to high cost base. Therefore, for a private developer is most conveniently and economically optimal use of cellular concrete in the construction of country cottages of approximately 200 square meters. m. Save on the foundation of the construction of cottages of this material is strictly impossible. You can use cellular concrete as filler walls of the frame house. In this case, the entire load takes the frame. However, the frame house building with the use of cellular concrete for the most part relates to a multi-storey building and to private developers interested. In addition, the thickness of the walls of said material reaches the two feet that for a small house lot. For cellular concrete is characterized by porosity, and therefore it has low density. An increase in the density for the sake of reducing the thickness of the wall will only lead to the fact that the material will lose many of their outstanding properties, such as the ability to breathe and keep warm. Houses of cellular concrete elevate people who want to build a rather large house for year-round and thus optimize their costs. Feature of the material is and what he needs protection from environmental influences. Despite the fact that the voids in the wall of porous concrete very small, they, however, very much, and gotten them wet, or wind can destroy the material. Therefore, the wall masonry of such concrete needs plastering, painting, or facing. Manufacturers of all types of cellular concrete is often claimed that the protection of these materials is not required. But if you decide to build a house literally for centuries, it is hoped that he will stand for no less than 100 years, oblitsevat building facade materials will be superfluous. The more that modern facing materials are varied and often quite beautiful. To protect porous concrete should be used only light facade materials. It is not recommended to surround the wall of a concrete from the outside masonry: brick simply nullify the beneficial properties of lightweight cellular concrete. The main problem is that the brick has a low aeropronitsaemostyu. And if you put it close to the cellular concrete, the steam coming out of the house will be reflected from it and come back into the room. This will lead to excessive moisture and improving the appearance of dampness on the walls. Do not forget that each material is optimal only if properly used. Enterprises producing aerated concrete of different densities, and the builder can select the type of block it depending on what part of the house he builds. Aerated concrete blocks can have a density of 350 to 700 kg / cu. m, respectively, are designed for different applications. Aerated concrete lowest density is suitable for insulating buildings and can not be used for building walls. Last erect a material density of 400 500 kg / cu. m. Moreover, aerated concrete density of 500 kg / cu. m can be used to build houses up to three storeys. Higher buildings should be erect, respectively, from the material of greater density. There just should be careful: the higher the density of aerated concrete, the lower its thermal insulation properties. In other words, the denser it is, the closer the properties of conventional concrete - cold and aeronepronitsaemomu material. In addition, the denser the wall, so it is harder and therefore requires a more powerful foundation. Therefore, in the cottage building block is the most screwed density of 400 500 kg / cu. m - that it optimally combines the advantageous properties of porous concrete, as well as its strength and weight. Large plants produce a variety of reinforced aerated concrete products and even special slabs. The latter, however, is more expensive than similar designs from the usual heavy concrete, but do not require too thick walls. To summarize, I would like to stress once again the characteristic features of cellular concrete: excellent thermal insulation, aeropronitsaemost, fire safety, durability and efficiency. The above properties make it extremely competitive in today's building materials market. Of course, this does not mean that everyone needs to build a house just out of the concrete. Just in some cases, this material is really the best for construction.
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