A panel house from which the walls. The construction of panel walls - interesting facts

2.   The design of civil buildings with walls of large-sized elements

1. Panel walls and their elements:

a) single-layer concrete panels;

b) 2, 3-ply concrete panels;

2. Horizontal and vertical panel joints.

3. Internal walls of panel houses.

1. Panel walls and their elements.

Wall panels in view of their considerable length and height with a small thickness do not have independent stability. This stability is ensured by fastening the panels among themselves, with the structures of the floors, etc.

Depending on the type of structural scheme, the wall panels are divided into bearing, self-supporting and hinged. Panels of external walls can be single- and multi-layered.

a) Single-layer panels are made of a homogeneous low-heat-conducting material (light or cellular concrete), the strength class of which must correspond to the perceived loads, and the thickness, in addition, take into account the climatic conditions of the construction area. The panel is reinforced with a welded frame and mesh.

On the outside of the panel have a protective layer of heavy concrete with a thickness of 20 ... 40 mm or decorative dense concrete (for protection against atmospheric influences) and on the inside - a finishing layer of cement or lime-cement mortar thickness of 10 ... 15 mm.

A good material for single-layer panels is cellular concrete with a density of 600 ... 700 kg / m3. The thickness of the panels of cellular concrete depends on the climatic conditions and is adopted from 240 to 320 mm. These panels are used for buildings with transverse bearing walls, and the outer wall panels are self-supporting. The end walls consist of two panels: an internal bearing - of reinforced concrete and an external self-supporting - of cellular concrete. Single-layer panels have simple design solutions and manufacturing technology.

Widely used single-layer claydite-concrete panels of class B5 with a density of 800 ... 1100 kg / m3. The outer surface of the panel has a 20 mm thick texture layer of decorative concrete, and the inner surface is a 10 mm thick finishing layer from the mortar that is placed in the mold when manufacturing the panel. After installing the panels produce its putty and painted on the inside or wallpaper.

b) Double layer panels   consist of a carrier layer of dense light or heavy concrete of class B10 ... B15 with a density of more than 1000 kg / m3 and a heat insulation layer - from heat-insulating lightweight or cellular concrete or rigid insulating boards. The thickness of the base layer for wall panels must be at least 60 mm, and placed on the inside of the room, so that it is also a vapor barrier. The thermal insulation layer is protected from the outside with a layer of decorative concrete or mortar 50 ... 70 with a thickness of 15 ... 20 mm. If a heater is used in the form of semi-rigid thermo-insulating slabs or laid down by the pouring method, the supporting reinforced-concrete layer is taken by the edges along the contour or the often-ribbed one.

Three-layer panels consist of two thin reinforced concrete slabs and an effective heat-insulating layer (insulation), laid between them. As a heater, semi-rigid mineral wool boards, mineral cork, cement fiberboard, asbestos-cement slabs, mineral wool mats on a phenolic bond, fiberglass mats, as well as rigid heaters - foam glass, foamkerite, foam silicate, etc. are used. Reinforced concrete layers of the panel are joined together by welded reinforcing cages. The inner layer of the three-layer panel is 80 mm thick and the outer layer 50 mm thick. The thickness of the insulation layer is determined by heat engineering calculation. Very effective are asbestos-cement panels, which can have a skeleton and frameless construction. The frame panel consists of two asbestos-cement sheets: the outer thickness of 10 mm, the inner - 8 mm and the frame between them from asbestos-cement bars of a special profile. Inside the panel, a heater is laid. Three-layer sandwich panels of three layers of fibrolite, glued together with cement mortar and faced with flat asbestos-cement sheets on both sides, are considered to be frameless. At present, wall panels made of plastics are used.

2. Horizontal and vertical panel joints

Joints between panels of external walls should be leakproof not to allow the formation of condensation at the junction, to have sufficient strength to protect the joint from the appearance of cracks in it.

Vertical joints by the way the panels are connected to each other are divided into resiliently and rigid (monolithic). When the device is resiliently coupled, the panels are connected by means of steel bonds welded to the embedded parts of the elements to be joined. In the groove formed by the quarters, enters the depth of 50 mm wall panel of the inner transverse wall. Connect the panels using a strap strip made of steel strip, welded to the embedded parts of the panels. To seal the joint into its narrow slit, a sealing cord of hernite is put on the glue or porosol on the mastic. On the outside, the joint is smeared with a special mastic - thiocal sealant. For insulation from penetration of moisture from the inside of the joint, a vertical strip of one layer of waterproofing or roofing material is pasted on the bituminous mastic. Vertical splice well is filled with heavy concrete. The disadvantage of resilient joints is the possibility of corrosion of steel bonds and embedded parts.

More reliable in operation are rigid monolithic joints. The strength of the joint between the elements to be joined is ensured by embedment of the connecting steel reinforcement with concrete. Between the bonded area of ​​the joint and the sealing, a vertical air cavity is formed, which serves as a drainage channel diverting the water that enters the seam and discharging it out at the base level. Often, a mineral wool liner wrapped in a polyethylene film or of a foam plastic is placed in the joint of the panels to increase its heat-shielding properties.

For the device of horizontal joints, the upper wall panel is laid on the bottom on the cement mortar. In this case, through a horizontal seam, densely filled with a solution, rainwater can penetrate mainly due to capillary suction of water through the solution. Thus, we see that to ensure the normal performance of walls from large panels for joints use various materials having a wide variety of physical and mechanical properties: fastening (steel), heat-insulating (mineral wool liners), waterproofing (ruberoid or insulating), binders and sealing (concrete and mortar), sealing (poroizol or gernite and mastics). All these materials have different durability and often a much shorter service life of the building. That is why when designing joints of panels and their execution, special attention should be given to the possibility of ensuring a high quality of construction works, using materials with good physical and mechanical properties for this purpose.

The joints between panels and plates are made in solution. However, in the case of incomplete filling of the joints with a solution in certain sections of the panels, there may be a danger of stress concentration. To prevent this phenomenon, cement-sand plasticized paste is used for butt joints, from which thin seams 4 ... 5 mm thick can be obtained. Such a paste consists of portland cement grade 400.500 and fine sand with the addition of a plasticizing and antifreeze additive of sodium nitrate in an amount of 5 ... 10% of the mass of the cement. Such paste, as it were, glues the panels together.

Wall panels in low-rise construction are increasingly being used, but few have a clear idea of ​​this technology. Quite a lot of confusion is made both by panel manufacturers and by the stewards themselves, who do not fully tell about different nuances in contrast to some panels from others. In this article we will try to get to know more closely with such a construction technology.

Classification of panel walls

In most Russians, the phrase "panel housebuilding" is primarily caused by associations with modern multi-storey panel houses or de with ever-memorable "Khrushchevs." Panel houses are not elite, but they are quite affordable for the middle class and are quickly built. It should be noted that the relative cheapness and speed of construction of such buildings can be explained by the use of large wall concrete panels.

Panels are building elements that occupy a rather large area and are relatively thin. Such panels are created from light cellular concrete or from heavy concrete in the factory. They are characterized by a rather high degree of readiness. Quite often, wall panels are created with finished exterior trim, as well as built-in door and window openings. The inner side of such panels is often ready for wallpapering or painting. The installation of panels is carried out very quickly with the help of a crane, so the builders can only seal the joints and carry out the work of interior finishing.

In terms of constructive basis, all panel buildings can be divided into three types: panel-frame, frame and frameless. In the first case, the frame and panels are a single supporting structure, in the second - the load is transferred to the frame, and in the third case - all the load is transferred to the bearing panel walls. It should be noted that frameless houses can be with bearing transverse walls, and with bearing longitudinal (including the inner wall). This technology has several advantages: there are no protruding columns inside the building, easy installation, savings in the construction of the frame. Most often the wireframe technique is used in buildings with non-standard and complex construction or in houses with a large number of floors.

All external panels are also divided into several types, depending on their purpose: hinged (the weight of the walls is completely transferred to the frame of the building), self-supporting (walls perceive only their own weight) and bearing (in addition to their own weight perceive the weight of the ceilings and roofs).

Also, the panels are one-, two- and three-layer. For the production of single-layer panels, lightweight cellular concrete is used, for double-layered panels - a reinforced concrete base with a heater is used, and for three-layer panels - two reinforced concrete casings with a heater between them. To date, developers are increasingly using three-layer panels, despite their high cost. Virtually all single-layer panels do not meet modern standards of heat-saving, despite the fact that they require less labor and materials.

On this, we finish the tour of the multi-story building. Perhaps someone will have a question, why was it necessary to talk about all this if panels of cellular concrete or heavy concrete are practically not used in the construction of residential individual houses? The fact is that you can conduct quite a large number of analogies with panels, which are usually used in low-rise construction. Thus, the above information will not be superfluous.

Building sandwiches

As everyone knows, in suburban housing construction, concrete panels are practically not used. In the event that you need strength and thoroughness - developers will use a ceramic large block, brick or a concrete monolith with a permanent formwork as a heater. Usually, panels are used in panel-frame and frame houses. The basis of these houses is wood or wood materials, combined with various heaters.

As mentioned earlier, in the supporting frames, voids are filled with different materials, including wall panels. It's clear that the main load is on the frame, that is, the panels perform an extremely protective role, protecting the internal premises from external influences (rain, snow, wind, etc.). When carrying out analogies with multi-storey construction, it will be a scheme of hinged or self-supporting panels that transfer their weight to the frame of the house. Such a panel must correspond to certain strength parameters, thus, strong materials are used as a basis: OSB, DSP, DSP and so on. In addition, the wall should protect the internal premises from the cold, for this, the panels should include a heater. In the final result, we get a so-called "sandwich" (two solid plates with a layer of insulation between them). In other words - the aforementioned three-layer panel, only with environmentally friendly and lighter materials, instead of reinforced concrete shell.

It should be noted that a simplified version of the three-layer construction can not provide the necessary tightness of the panels, which should not allow both moisture and air to pass through. It is for this reason that the panels also include vapor barrier membranes, windproof and waterproofing films, as well as gypsum, as a draft version for interior decoration. Thus, the comparison with the sandwich is justified by 100%.

Depending on the technologies involved during the construction of the house, sandwich panels are for the roof of the house and the ceiling, for internal partitions and for external walls. Different queries are made to different panels, so that externally the same panels still differ from each other. For example, in roofing panels the density of mineral wool insulation should not exceed 150 kg / m3, and in wall panels - not lower than 110 kg / m3. Also, such requirements determine the cross-section of the edges of the frame, the necessary thickness of the layers of thermal insulation, the method of making the hermetic connection of different parts of the entire structure, and so on.

To create a layer of insulation in sandwich panels, usually use mineral wool layers or polystyrene. It should be noted, in addition to high thermal insulation properties, sandwiches with foam plastic is much easier than with a mineral wool insulation.

Panel-frame construction

Panel panels used in panel-frame housing are not only enclosing, but also perform the functions of load-bearing structures. Due to this, they have a fairly stable and strong frame made of special blocks (I-beam, channel, etc.) and wood.

These panels are practically ready walls of the house. OSB protection plates in combination with the frame create a reliable mechanical base, which is able to withstand loads, both from floors and from the roof. Inside the panels are placed communication elements and insulation, door and window openings are also built into the panels. On the inside, the wall panels are usually finished with a gyro for finishing.

The production of wall panels is carried out in factories with very high accuracy (the maximum deviation from the specified size is only a few millimeters). After this, the panels are transported through a special transport to the construction site, where they are mounted in just a few days. It should be noted that during the construction of a panel house, there is no need for a separate construction of the frame of the building. The role of this frame is played by wooden beams, which are pasted into the panel (from all sides) in the factory.

Almost all modern manufacturers use OSB (Oriented Strand Board) or OSB (oriented chipboard) to create barrier plates. Plates with oriented flat chips are the result of high-tech wood processing and have an ecological harmlessness (which can not be said about chipboard) and high strength characteristics. Quite often the frame of panels is formed by glued beam, which in due course will not change its geometry. Thus, a panel-frame house constructed on the basis of wooden materials will not be subject to any shrinkage processes.

Fencing panels also use a waterproofing film, wind protection and so on, as in other sandwich panels. But heaters can be used different. Quite popular steel insulation made of mineral wool, which is very effective against the cold, almost do not absorb moisture and do not burn. However, when creating some panels, use other types of insulation, including expanded polystyrene. Such a method of insulation panels should be considered separately, because no wonder manufacturers make such panels in a separate category called "SIP-panel" (Structural Insulated Panel). For the production of slabs, OSB-3 is used with a thickness of about 12 millimeters, and PSB-25 polystyrene is used for insulation. It should be noted that all these components under pressure are glued into a fairly strong structure. Thanks to the monolithic bonding, such panels (with a width of 1250 millimeters) are able to withstand about 10 tons of vertical load and a transverse load of about 2 tons per square meter of area.

Due to the physical properties of materials used during the creation of materials, SIP panels are resistant to temperature changes from -50 to +50 degrees Celsius, are not prone to rotting and freezing, and also do not absorb moisture. Also important is the fact that the glued foam polystyrene does not allow the plating plates to bulge during shear or axial compression. This feature makes SIP panels the optimal material for the construction of external walls. Another positive quality of SIP panels is environmental cleanliness, used in their creation, materials, as well as their high performance in terms of fire safety. The panels themselves are technologically both in production and in subsequent processing.

As an inference, we can say that panel building in the sphere of low-rise housing construction is gaining in popularity. Panel houses are of low cost in comparison with brick or brick, short construction time, as well as the geometric accuracy of the elements used.

Internal walls of panel houses are, as a rule, single-row cut. According to the length of the walls, a cut is used, corresponding to the dimensions of the structural and planning cell. In the presence of doorways in the panel, they are projected to be closed with a jumper above the opening and a jumper (or reinforcement link) below it. In addition, T- and L-shaped products are used for this cut (Figure 18.2). The panels of the inner walls work on the eccentric compression according to the static scheme of the thin plate, which is unfolded along the vertical edges by walls perpendicular to the direction, and along the horizontal ones - by ceilings.

The panels of load-bearing walls usually have a continuous section. Multiband panels are used in the case of using elements for ventilation walls with ventilation ducts. The material of the wall panels is heavy concrete. Walls made of lightweight concrete are only used when it is technically feasible or economically feasible. The minimum class of concrete walls for compressive strength from heavy concrete B 15, from light B 10.

The thickness of the panels of internal bearing walls is determined by the strength of the middle section of the panel, the layout of the support unit of the ceilings on the wall and the requirements for sound insulation. The minimum weight of 1 m of solid panels formed from heavy concrete, if applied in acoustically uniform walls and partitions, is 400 kg with an acoustic insulation index of air noise R w = 50 dB, 300 kg at R w = 45 dB and 150 kg at R w = 41 dB, which corresponds to the thickness of the panels 160, 120 and 60 mm. If more sound insulation is required in panel buildings, acoustically heterogeneous structures with flexible screens or single-layer structures of greater thickness are used. Requirements for sound insulation are taken into account when assigning not only the cross-sections of the enclosing structure, but also its interfacing with the rest of the building elements. For this purpose, a mutual pass to a depth of at least 30 mm, a device of keyed keyed couplings in joints with load-bearing structures, and sealing with sealing elastic gaskets (see Figure 18.3) is envisaged in the joints of the internal walls with external and overlapping ones.

The wall panels are designed with concrete without a calculated vertical reinforcement. At the same time, they provide for separate elements of computational reinforcement (in crosspieces above the openings) and constructive double-sided reinforcement by vertical cross-section frames in steps of 600-900 mm across the entire plane of the panel, as well as steel bonding elements. Reinforced concrete panels (with the estimated vertical reinforcement) are rarely used, mainly in the lower floors of high-rise buildings, if it is necessary to maintain a uniform wall thickness.

Horizontal joints of the panels ensure the strength of the structure under force. These joints are designed to be contactable with the transfer of a vertical load from the overlying wall panel to the underlying wall through a mortar or concrete seam or platform with the transfer of load through the support sections of the floor panels.

The platform joint (Figure 18.4) is the most common, as it allows the use of products of the simplest form. Usually it contains three seams from a cement slurry: two horizontal (under and above the overlap) with a thickness of not more than 20 mm and one vertical (between the ends of the floor elements). The strength of the walls in the joint area depends on the strength of the solution in them and the size of the platform for supporting the floors on the wall. When the strength of the solution varies from zero to 15, the strength of the wall in the junction zone increases by a factor of 2.5-2.7. Therefore, the requirement to install panels in a strong solution is mandatory.

The contact joint (Fig. 18.5) is performed with supporting ceilings on special consoles of internal walls or with the establishment of reinforced concrete bearing outlets - the "fingers" of decking of overlappings in the corresponding grooves along the top of the wall panel, in analogy with the used support of the overlaps on the outer bearing walls (see). . The disadvantage of the first option is the need for the device consoles. They are undesirable in the interior and complicate the production of panels. The disadvantage of the second is the danger of violating the soundproofing of the ceiling in the places of its loose abutment to the wall (between the "fingers") and their detection in the interior.

The contact joint is used for mating panels of heavily loaded walls with multi-hollow floors. It eliminates the danger of brittle crushing of thin reinforced concrete vaults over voids. However, hollow-core reinforced concrete ceilings are used in platform joints when the strength of the supporting sections of the overlap is increased by embedding the voids.

Horizontal joints of wall panels are usually designed flat. Crimped horizontal flat joints usually provide the perception of shearing forces from the effects of wind due to friction and adhesion of the solution. For more intense horizontal impacts, for example seismic, the strength of horizontal shear joints is increased by the construction of reinforced concrete or steel keys (Figure 18.6).
Strength and sound insulation of vertical joints of panels of load-bearing walls, at the same time, provide a device of key-shaped keyed connections with the transfer of the spacer from the keys to the steel connections between the wall panels, in analogy with the solution of the vertical joints of the external walls (see).

The requirements of industrialization lead to the expansion of the functions of structures that saturate the elements of engineering equipment and networks. In the panels of the internal walls there are smoke and ventilation ducts, heating registers, heating pipes, hidden electrical wiring (Figure 18.7). With the location of heating registers of thin steel pipes in the concrete panel of an internal carrier or a self-supporting wall, it combines with the structural functions of the heating element - the heating panel in the heating system in the panel on top and below are provided with trimmings that allow the risers to be joined during the installation of the building. The arrangement of the risers at the edges of the wall panels adjacent to the outer walls improves the distribution of temperatures on the inner surface of the walls in the joint zone.

Walls with smoke channels that divert gases with a temperature of up to 600 ° C (from solid fuel panels) are allowed to be used in buildings with a height of no more than five floors. Such walls are designed by self-supporting and are made of panels (smoke ventilation units) in height, molded from heat-resistant concrete.

Walls with smoke channels, which divert gases with a temperature not higher than 200 ° C, are also designed to be self-supporting, panels of such walls are formed from ordinary heavy concrete of class not lower than B 30 or from light concrete of class B 15.

Walls with ventilation ducts are designed by carriers, self-supporting and non-bearing. Depending on the number of storeys of the building and its ventilation system, ventilation units with a height of one-level arrangement of round or oval channels with a cross-sectional area of ​​at least 200 cm 2 or shafts with large channels of rectangular or square cross-section with a ratio of sides up to 1: 1.5 are used. Separation of channels in the junction of blocks and mines is ensured by sealing of horizontal joints. Ventilation blocks are used for load-bearing and self-supporting walls, ventilation shafts - for self-supporting or non-load-bearing structures installed on floors (in high-rise buildings).

Ventilation panels and shafts installed above the attic floor or uncarpeted cover are designed with heat-insulated, heat-resistant walls in external areas of at least 0,85R 0 TP for external walls.

Smoke extraction chambers (in buildings with a height of more than 9 floors) are designed with concrete self-supporting or non-bearing with a fire resistance limit of at least 1 hour.

The layout in the walls of the elements of engineering equipment or networks should not lead to a decrease in their crack resistance or sound insulation. For this purpose, structural reinforcement of ventilation units and shafts is provided with welded nets along the face planes and additional reinforcement at the surface of the wall panels at the locations of the buried electrical wiring ducts. In the inter-apartment wall panels, separate channels for concealed wiring in adjacent apartments are provided, the device of through holes in the panels in the locations of the holes for the installation of the decoiled boxes, plug sockets and switches is excluded.

Lift shafts They are made of heavy concrete class B 20 in the form of space-wide reinforced concrete blocks-tubing for one or two elevators. In combination with them, a flat reinforced concrete slab of the mine cover and a pillar are used for the buffer of the elevator car. The elevator shafts are designed as self-supporting structures with a wall thickness of at least 100 mm. To ensure sound insulation, the walls and foundations of the shaft are separated from the adjacent structures by an air gap. A clearance of 20-40 mm between the shaft and the interstorey floors is filled with soundproofing gaskets.

The inner walls of monolithic and prefabricated-monolithic buildings are designed in monolithic, from a heavy class for compressive strength not lower than B25 and a thickness of at least 160 mm, in houses up to 16 floors with a small step of the transverse walls. In houses of greater number of storeys (or with a wide step of the transverse walls), the thickness of the inner walls is not less than 200 mm. As well as panel, monolithic internal walls project mainly concrete (without settlement vertical reinforcement). The structural reinforcement consists of transverse welded frames in steps of 600-900mm, connected by individual horizontal rods with a pitch of 400-500mm into a single reinforcement block. Its constituent elements are the calculated reinforcement frame above the door lintel and the structural skeletons along the remaining contour of the opening.

These techniques are the main ones when designing elements of monolithic internal walls. The remaining constructive methods are directly related to the type of adjacent structures (prefabricated or monolithic) and the scheme of their concreting (simultaneous or sequential).

With simultaneous concreting of internal walls and ceilings in the bulk-formwork formwork), the slabs are not inseparable with the accompanying double reinforcement on the support. However, this technology is associated with the stage-by-stage concreting of internal and external (their inner layer) walls. To ensure their joint work, reinforcement keys are provided with a step of not more than 900 mm (figure 18.8), which enter between the elements of prefabricated structures or in the monolith of the adjacent wall.

Concreting in the formwork provides the simultaneous erection of the outer (inner layer) and internal walls (longitudinal and transverse), which greatly simplifies the construction of reinforcement links between them: they are made of bent reinforcing cages (Figure 18.9). On the height of the floor skeletons are connected with each other by separate rods in at least two levels.

For the arrangement of inter-floor connections, vertical reinforcing frames are 200 mm higher than the level of the interstitial overlap, which allows them to "overlap" with the carcass above the located floor. In places of overlapping, the wireframes are tied with knitting wire.