To build ordinary lintels over door and window openings, you can use any ready-made structures, including available materials (for example, in Kuban, I often saw how openings were blocked by the common posts there, to which grapes were tied).
With arches and arched lintels it is more difficult - they need to be made separately for each opening.
As a rule, the technology for constructing arches for a particular house should be provided for at the stage of drawing up the house project. Then its shape, span, lifting boom, etc. are selected. including the material from which you will make it
Arched lintels and ceilings have been known since ancient times. Arches have been known in construction since very ancient times, so much so that they even became a feature inherent in some schools of construction (think, for example, Italy - arches immediately come to mind).
Their uniqueness in construction is that from any vertical pressure or load they receive even greater strength, since only additional compression occurs along the radius of the arch.
Arches were previously made of ordinary stone or brick, usually solid. Currently, their main advantage is not any design advantages, but, first of all, our desire to bring a special zest to the design of the house, some kind of peculiar southern charm, give it a certain style and unusual design, and a wide variety of modern building materials allows you to make arched lintels from almost anything.
Stone and masonry lintel arches
As already mentioned, earlier arches were built together with a wall that was entirely made of solid brick and the arches were its structural element, inseparable from the overall structure of the wall.
Read also: Since this is rarely done now, the arches are made separately and serve to decorate the facade of the house. For this reason, clinker or sand-lime brick is used for their construction, which goes well with almost any material from which the main part of the wall is made, be it cellular or aerated concrete - properly prepared masonry mortars will reliably bind them together. Taking into account the fact that sand-lime brick is quite inexpensive, we get another advantage in using it in arched construction.
How it's done.
The bricks in the arch are laid on ordinary cement-lime mortar. In this case, the greatest thickness of the seam cannot be more than 20 millimeters, and the smallest 5.
The required amount of brick for laying an arched lintel depends on the thickness of the walls and the width of the opening that needs to be blocked.
So, for example, during the construction of the so-called “bow arch” (read more about bow arches), an odd number of bricks are placed in the arc of the arch itself, and the castle brick crowning it (lock brick) is placed at its immediate top to fasten the structure.
The calculations here are as follows: for example, for an arch with a thickness of 120 millimeters and a span of 120 centimeters, 17 pieces of brick will be required, but if the span is 1.5 meters, then 21 pieces will be needed.
Before you begin laying the arched lintel, you must clearly plan the location of the bricks in it in advance. To do this, a so-called “circle” or guide template is made on which the bricks will rest when performing masonry work.
The circle is made from boards that will repeat the shape and outline of the future arch (if the arch is large and designed for a long span, then the circle is made from several large boards), then it is secured and installed on both sides on temporary supports, then using wedges and spacers are adjusted to the place of masonry.
Be sure to wet the brick well before laying the arched lintel.
I recommend covering the part of the brick that will not be in contact with the mortar with a water-repellent compound, especially if you do not plan to further finish the brick in the future - then you will save time on washing the brick from the mortar.
The laying of the arched lintel is always carried out simultaneously and evenly on both sides of the circle in order to avoid distortions that occur under load.
It is very important to lay the lower bricks of the structure with the “spoon” part perpendicular to the action of the spacer forces, since large forces act in its lower parts.
The laying of bricks in the arch must be completed exactly at its top, that is, exactly in the middle of the radius of the upper arc, where the key brick is laid on the mortar (it must be laid with emphasis and smoothly, but without knocking on it, so that the structure does not “break apart”).
The wedges - the spacers that held the wooden structure of the circle together - can be loosened an hour after the complete completion of the bricklaying work in the lintel - this will allow the brick to sit more tightly on the mortar and compact it, as a result of which the voids that arise during the laying will eliminate themselves. After 4-5 days, after the solution has completely set, the wedges can be removed completely and the circle structure can be dismantled.
Figure 1: Schematic drawing. Arch masonry
1. arch thickness
2. top of the arch
3. minimum seam thickness is 0.5 cm
4. keystone-brick at the top of the arch - inserted last
5. front – front part of the arch (archivolt)
6. maximum seam thickness – 2 cm
7. span (opening width)
8. supporting stone - an element laid directly in the arch support
9. arch boom (lifting height)
10. arch support heel. From the heels, simultaneously on both sides, begin laying the arches
Diagram No. 2. Laying bricks in the lintel
The thickness of the arch (one row of masonry or two with ligation of bricks) depends on the thickness of the wall. The width of the opening also affects the placement of bricks in the masonry and the thickness of the arch, that is, it determines its appearance.
How to check the layout of bricks
It is not difficult to check the correctness of the line of curvature of a segmental arch with a radius greater than half the width of the opening and determine the placement of bricks in it. To do this, below the top of the arch at a distance equal to the radius of its arc, a board with a rotating strip or cord is attached.
- rotating rack or cord
- board located at the level of the center of the arch circumference
Reinforced concrete arches - lintels
In the usual construction of a house with one’s own hands, they often use monolithic reinforced concrete arches instead of brick arches. They can be made from pre-prepared shaped elements, which will significantly reduce the time spent on them and simplify the process of their construction.
Arch in ordinary, removable formwork.
So, for example, if you want to cover a very wide opening with an arched lintel, then this type of arches is perfect, because steel reinforcement in concrete has the ability to withstand greater loads than structures made of masonry materials.
Other advantages of poured, monolithic arches include the low cost of work taking into account the price of building materials, the ability to make arched lintels of “tricky shapes” (for example, with “pouring” under the canopy of a house), and the fact that they can be made adjacent to the load-bearing wall of a house built from any materials, even from adobe.
What makes their implementation difficult is that, first of all, it is very difficult to do them alone, the reinforcement process is complex, and besides, you will have to call a welder if you do not know how to do welding work yourself.
How to do it.
An arched ceiling made using formwork requires the preliminary production of a form that will be supported by supports specially made for it.
The reinforcement is bent to the shape of the future structure and tied together with wire for strength or welded by welding (less often, but more reliable).
The resulting reinforcement structure is carefully placed in a sealed formwork and filled with concrete.
If possible, it is better to combine the monolithic arched lintel itself with the concrete belt of the house wall, for which you can connect the formwork and reinforcement structures of the arch and wall and fill them with concrete at the same time. With this installation of the arch, the entire structure will withstand higher loads.
The reinforced structure of the arch, which is poured with concrete, consists of lower and upper horizontal-longitudinal rods connected vertically with wire or clamps.
When making a reinforcement structure, think in advance about the moment so that the solution filling it ensures its complete filling, including so that on the outside of the arch it surrounds the reinforcement by at least 2 centimeters; for this, consider the possibility of creating such a gap in advance, usually for this purpose on the reinforcement put on metal circles or washers of a suitable size.
Also, do not underestimate the size of that part of the arch that will rest directly on the wall. As a rule, it cannot be less than 8 - 10 centimeters, and preferably more, 16-20 centimeters.
Concrete should be placed in formwork with a form as carefully as possible, to prevent delamination of the mortar, and to bayonet it to more tightly cover the reinforcement with the mortar. Also be sure to take note that concrete during the construction of arches must be poured continuously, this is very important.
After pouring, the formwork itself can be removed within two weeks. But keep in mind the fact that the concrete solution rarely reaches full strength before four weeks.
An arch made using permanent formwork from shaped elements made of cellular concrete.
This is one of the most simple ways construction of arched ceilings and lintels.
It differs from the previous one in that instead of the usual removable plywood-board formwork, ready-made U-shaped elements are used, which are pre-made from cellular concrete.
Concrete is poured into this cavity formed between the vertical axes of the letter U, having previously installed the reinforcement there.
There is only one downside - it's expensive. In order to get a more or less smooth arch line you will have to buy a large number of these U-parts (see Figure 4). It makes sense to purchase them only if the opening that will have to be blocked is very large, from two meters and above. Otherwise, the arched ceiling will not have a semicircular shape, or there will be a lot of scraps left that will be difficult to adapt somewhere.
Read also:
How to install arches in this way
The U-shaped elements must be assembled with glue, having previously been cut to the desired angle for a tight connection and obtaining a correct and smooth arc of the arch.
Otherwise, the procedure is the same as with wooden formwork: reinforcement is laid with pre-fitted protective spacers to create an outer layer of concrete (at least 2 centimeters, as in the case of wooden formwork), then concrete is poured and compacted by bayoneting using metal rod.
Shaped U-shaped elements are nothing more than permanent formwork.
Do not remove the supports supporting the structure of the freshly poured arched lintel for 2 weeks to allow the concrete to set better.
If you need to continue further masonry of the wall at the junction of the arch, then simply cut the masonry material along the line forming the arched bend as the masonry proceeds, and simply fill the resulting voids and irregularities with masonry mortar - in principle, everything is the same as what we considered when we talked about installing a brick arch .
Arch in permanent formwork made of thermoblocks.
This method is suitable even for beginners in DIY construction.
Such an arched ceiling can be made in a house built from almost any building materials, including polystyrene foam blocks or ceramic blocks; in this case, the so-called “core” is first made directly above the arch, that is, a direct reinforced lintel. There is very little waste of building materials with this method, and, therefore, there is also a small saving.
How to make an arch in this way (i.e. using polystyrene foam) - Drawing diagram 5
First, in the opening in the place where the arc of the arch begins (about half a meter from the floor level), the thermoblocks themselves are laid. Thermoblocks are temporarily supported using supports.
Over the future arch, polystyrene foam elements are installed, which will serve in the future as permanent formwork. They install the reinforcement structure.
Next, in the side surfaces of the polystyrene foam blocks, along the pre-defined line of the proposed arched lintel, a slot is made into which a gasket from a steel sheet of the required width is inserted, which in turn will prevent the mortar from entering the internal voids of the thermoblocks, which are located directly below the arch itself (thereby forming vault).
The concrete, under its own weight, will slide along the voids of the thermoblocks, and the steel sheet - the bridge will stop it.
After the concrete has hardened for 2 weeks, the temporary supports on which the arched structure rests can be removed and the blocks can be dismantled BELOW the lintel forming the vault of the arch.
Prefabricated arch made of cellular concrete blocks
Also enough easy way to do it yourself.
Here the arch is rather imitated, but outwardly it looks the same. In this option, the entire load falls on a conventional rectangular lintel, to which blocks of cellular concrete are connected (Figure 6).
How this type of arches is made.
The width and length of the opening are calculated, after which ordinary concrete lintels are installed under them, which are used in the construction of any houses, including brick ones.
Blocks cut to the desired shape are glued to the bottom of the lintel. For an arch with a span of 120 centimeters, you will need only two trimmed blocks; otherwise, the wider the opening, the more blocks you will have to trim and shape to fit the circle. This is done as with any work with cellular concrete with an ordinary hacksaw and a grinding machine (it is better to level the surface).
The glue is applied both to the top surface and to the side for better attachment to the slopes.
The entire block structure is supported by support posts while the glue dries (this time is indicated on the package with construction adhesives), but in any case, wait at least 3-6 hours, after which the supports can be removed.
Required materials for the construction of lintel arches - Table 1.
Arch design | Necessary materials |
|
Masonry 25 cm thick | solid, clinker or sand-lime brick, cement-lime mortar, formwork (circling) |
|
Reinforced concrete –in traditional formwork | reinforcement, concrete mixture, formwork, inventory racks |
|
In permanent formwork: FromU-shaped shaped elements From shaped elements made of polystyrene foam | U-shaped shaped elements – 5 pieces, reinforcement, concrete mix, inventory racks shaped elements, hollow wall blocks, reinforcement, concrete mixture, steel sheet, inventory racks |
If you are planning to make an arch with your own hands, then remember:
Laying a wall over an arched lintel requires more work than regular brickwork. Each element of the horizontal row adjacent to the arch must be trimmed in accordance with its curvature.
Even if the load-bearing walls are built from porous ceramic blocks, for arched lintels with a small radius it is better to use traditional-sized bricks.
Scheme drawing No. 3. Reinforced concrete arches. (In ordinary, traditional formwork)
The numbers in the figure indicate:
1. reinforced concrete wall belt
2. clamps – transverse reinforcement with a diameter of at least 4.5 mm or 0.2 the diameter of longitudinal reinforcement, located in increments of 8-10 cm
3. reinforcement frame of the wall belt with working reinforcement rods with a minimum diameter of 12 mm. The frame of the belt is the reinforcement of the upper part of the lintel. The working reinforcement is joined with an overlay, the length of the overlay is about 20 cm
4. support of the lintel on the wall – about 15 cm
5. lower reinforcement of the arch from rods with a diameter of at least 12 cm
Scheme drawing No. 4. Reinforced concrete arched lintels. (In permanent formwork made of shaped elements made of cellular concrete)
1. reinforcement frame of the lintel
2. plastic pads that create a gap for the concrete layer protecting the working reinforcement
3. U-shaped shaped elements made of cellular concrete. They are trimmed to form the desired arch shape. The elements are joined using an adhesive solution.
Scheme drawing No. 5. Arch in permanent formwork made of thermoblocks made of polystyrene foam
1. The reinforcement frame of the lintel is placed in thermal blocks made of polystyrene foam. The entire structure is filled with concrete
2. shaped element of the lintel – thermoblock made of polystyrene foam
3. line of the designed arch, along which a groove is cut in the thermoblocks
4. gasket made of steel sheet (you can use a strip from a piece of fiberboard)
5. wall made of thermoblocks filled with concrete
6. temporary supports
7. dry-laid polystyrene foam thermoblocks
Diagram No. 6. Combined arched lintel
It is carried out using a prefabricated lintel with cellular concrete blocks glued underneath.
On the image:
1. The size of the lintel support on the wall is 20-25cm
2. precast concrete lintel
3. a block of cellular concrete, trimmed in such a way as to lay the lintel at the desired height
Cylinders intimate accessories 5 m strip for PVC balloons... Memo for the gardener - mass...
Laying lintels and arches.
In masonry, the area that is located above a window or door is called, depending on the configuration, a lintel or an arch.
There are several types of jumpers:
Prefabricated reinforced concrete lintels. They are used in cases where the floor slab is placed on the wall, directly at the level of the top of the future window or door of yours, and the load of the slab falls on the wall.
Non-load-bearing or ordinary brick lintels. They are used in cases where the load from the floor slab falls on the area of the future window or door, while the width of the openings can be no more than 2 m. The same rules are followed here as with ordinary masonry, namely, dressing and horizontality of laid out rows. The recommended number of rows in such a masonry is from 4 to 6, and the width should be 50 cm wider than the opening.
Laying of ordinary lintels: a - facade; b - section; c - masonry on plank formwork; d - masonry on inventory circles. 1 - reinforcing bars; 2 - boards; 3 - wooden circles; 4 - tubular circles.
The masonry is carried out using formwork, which must have a strong structure. The formwork rests on the edges of specially produced bricks, which are cut down after construction work.
It is also possible to install the formwork in specially left furrows, which are laid after the formwork is removed. In cases where the opening width exceeds one and a half meters, it is possible to install formwork on a special structure.
A solution of a grade of at least 25 and at least 2-3 cm is applied to the formwork, and at least three pre-prepared iron rods (reinforcements) are pressed into this solution. The diameter of the rods is from 6 mm and they should extend into the masonry of the wall by 25 cm.
Wedge and beam lintels. Usually laid out from ceramic bricks, forming wedge-shaped seams. In the lower part the seam should be 5 mm or more, in the upper part 25 mm or less. The masonry is carried out using formwork that is installed in advance. The outermost bricks of the lintel rest on specially prepared stones called the heel. The heel is hewn out of brick at a certain angle or made in a factory. It is not recommended to carry out this type of masonry with an opening width of more than 2 m.
The number of rows in wedge and beam lintels should be a multiple of two. The masonry is calculated in advance and carried out on both sides at once, converging in the center. The central row of masonry is called the castle row; it should be located vertically in relation to the formwork.
Arched lintels and vaults. This type The masonry has an arched shape, where each row of masonry in the arch should be located perpendicular to the formwork.
Figure 35. Laying of lintels: a - wedge-shaped; b - archery; c - arched; g - masonry seams. 1 - direction of the reference plane: 2 - castle brick; 3 - cord; 4 - square template; 5 - wedges.
The perpendicularity of the rows is determined by a cord secured in the center of the circle on which the formwork is installed. The method of constructing arched lintels and vaults is similar to wedge and beam lintels. The construction of this type of masonry is allowed in openings whose size ranges from 3.5 to 4 m.
Requirements for formwork. It must have dimensions that allow free removal of formwork and strength that can withstand loads in various atmospheric conditions.
For arched masonry, from 5 to 20 days, for wedge masonry, from 5 to 24 days.
Requirements for seams. All seams, both longitudinal and transverse, must be completely filled with mortar to avoid shifting of individual bricks, and subsequently the entire masonry.
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Reinforced concrete and brick lintels are used in brickwork, the most common of which are reinforced concrete. Brick lintels, in turn, are ordinary and wedge-shaped, and wedge-shaped brick lintels are straight (or flat) and arched. Arched lintels are simply called arches and are distinguished by the height of the rise (or the length of the circular arc): arched, semicircular, lancet, etc.
Brick lintels have higher decorative qualities than reinforced concrete ones and are more suitable for brickwork. True, if the masonry is intended for further plastering or cladding, this advantage does not make sense.
The construction of brick lintels is more labor-intensive, especially when choosing a wedge lintel. As a rule, they are performed only by experienced masons.
If there is a narrow partition (less than 1 m wide) between two brick lintels, the laying of the rows between the lintels is carried out using the same mortar as the lintels. To make ordinary brick lintels, use a mortar of a grade no lower than M-25; for wedges - a solution of a grade not lower than M-10. Seams in the masonry of lintels in mandatory completely filled with solution. Laying in a wasteland is unacceptable. The bricks used are selected (without defects), full-size, strength grades not lower than M-75. The laying of lintels always begins with bonded rows.
For openings with direct termination more than 2 m wide in individual construction, only reinforced concrete lintels are used.
Ordinary brick lintel
At the level of the top of the opening (when the masonry has been brought to this level), formwork is installed, for which strong boards 40-50 mm thick are usually used. The formwork is arranged taking into account the completion of a quarter along the upper edge of the opening (if a quarter is necessary). The formwork is supported in the grooves left when laying the slopes of the opening. Instead of furrows, it is possible to rest the formwork on bricks released from the masonry at the required level (based on the principle of creating a groove). If the opening is more than 1.5 m wide, the formwork is additionally supported by wooden posts (support beams firmly installed in the center of the opening). You can support the formwork only on beams, without grooves or brick outlets: in this case, two beams are installed on each side of the opening (and additionally in the middle if the opening is more than 1.5 m wide).
The solution is spread on the formwork in a layer of 20-40 mm. Reinforcement in the form of rods with a cross-section of 4-6 mm is laid on the mortar bed at intervals along the thickness of the masonry of half a brick (i.e., every half brick, the next rod is placed), but not less than three rods over the entire width of the wall (the interval between rods is reduced if the wall is thin). Under the future quarter (if there is one according to the project), additional reinforcement bars are laid. For corrugated rods (periodic profile), a diameter of 4 mm is sufficient; smooth rods must have a diameter of at least 6 mm. Instead of rods, you can use reinforcement in the form of steel strips with a section size of 1 x 20 mm. The strips are laid flat, according to the same principle as the rods.
The reinforcing bars are embedded (recessed) into the mortar to the same depth, so that they are approximately in the middle of the mortar bed along its thickness. The ends of the reinforcement on both sides of the opening must rest on the brickwork (not on the formwork) by at least 250 mm. Smooth bars must have bends (hooks) at the ends (an additional length is required to bend the ends of the reinforcement, and not the 250 mm mentioned above). These “hooks” are bent around the brick in the masonry.
Ordinary lintels over openings 1.5-2 m wide are arranged with a height of 5-6 rows of masonry; for openings of smaller width, a working lintel height of 4 rows is sufficient (the minimum height of a brick lintel is a quarter of the opening width). The seams in the lintel masonry must be strictly tied, both in the transverse and longitudinal directions.
When all 5-6 rows of masonry have gained sufficient strength, the board formwork is dismantled. On average, the formwork is removed 12-24 days after the completion of the lintel laying. The better the weather conditions, the faster the masonry will gain strength. Thus, at an outside temperature of up to 5 °C (but not less than 1 °C), you must wait 24 days before removing the formwork. At a temperature of +5...10 °C, the lintel is kept in the formwork for 18-24 days: at a temperature of 10...15 °C - 12-18 days; at a temperature of 15...20 °C - 8-12 days; at temperatures above 20 °C, 5 days are enough. These recommendations are given in the minimum acceptable time frame and are suitable only for ordinary and reinforced brick lintels in which there is no expansion due to the inclination of the stones.
After dismantling the formwork, the furrows into which it rested are filled with bricks or filled with mortar. If the formwork was supported by bricks released from the masonry, they are cut down.
Wedge brick lintel
To install a wedge lintel, like an ordinary one, install formwork boards and spread the mortar. In this case, there is no need to lay reinforcement. Bricks are used either ordinary or special, wedge-shaped (wedge-shaped).
The inclination of the bricks forms a spacer (wedge). The angle of inclination is calculated when completing the project and transferred to a template, which is then used when laying the lintel.
After installing the formwork, markings are made on it for the location of future rows of masonry, taking into account the thickness of the seam. Unlike conventional masonry, the bricks will be positioned vertically (i.e. almost vertically), and the markings will be made on a horizontal plane. The number of rows should be odd, and the middle row should be placed strictly in the middle of the opening. The central vertical row of bricks is called the castle row, since it closes the lintel masonry.
The brick is placed on an edge (on a poke or on a spoon) from the edges of the lintel to its middle, with a slope at the edges. The masonry is carried out simultaneously from both edges, with the obligatory bandaging of the seams between the rows. The correctness of the inclination is checked with a cord, the end of which is fixed at the place of the design intersection of the seams.
The middle brick is literally wedged into the masonry last (it should fit tightly between adjacent bricks, wedging the lintel and providing spacer). If necessary, the castle bricks are pre-ground. The middle brick, unlike all the previous ones, is installed vertically. In order to move from the calculated angle of inclination (at the edges of the lintel) to the vertical seams adjacent to the middle brick, the seams between the bricks of the wedge lintel when using ordinary bricks are arranged with a variable cross-section (in the form of wedges): in the lower part - at least 5 mm wide; in the upper part - no more than 25 mm. When using wedge bricks, the need to make wedge-shaped seams, as a rule, disappears.
Brick lintels are not used in the construction of buildings with likely uneven ground settlement. If the structure is on a soil foundation with uneven settlement, then even with the installation of the necessary expansion joints and making the right choice It is better to make the foundation lintels over the openings from reinforced concrete.
Wedge lintels are kept in the formwork (before its dismantling) for at least 10 days, depending on weather conditions. At temperatures up to 5 °C (but not less than 1 °C), the minimum holding period is 20 days, at temperatures of 5...10 °C - 15-20 days, at outside temperatures above 10 °C - 10-15 days.
The part of the wall that covers a window or doorway is called a lintel. If the force of gravity of the floors is transferred to the wall directly above the opening, load-bearing precast reinforced concrete lintels are used. If there is no such load, to cover openings less than 2 m wide, reinforced concrete non-load-bearing or ordinary brick lintels are used in the form of masonry on high-strength mortars with reinforcing bars that support the bricks of the lower row.
Instead of ordinary ones, wedge lintels are sometimes made, which at the same time serve as architectural details of the facade. For spans up to 3.5...4 m, arched lintels are erected. This type of masonry is also used to construct vaulted ceilings (vaults).
When laying lintels, all longitudinal and transverse seams are completely filled with mortar, since such masonry works not only for compression, but also for bending. When the vertical joints are weakly filled with mortar, under the influence of loads, individual bricks first shift, and then the masonry collapses.
Rice. 52. Laying a regular lintel:
a - facade, b - section, c - masonry on plank formwork, d - the same, on inventory tubular circles; 1 - reinforcing bars, 2 - boards, 3 - wooden circles, 4 - tubular circles
Row lintels (Fig. 52, a, b) are laid out from selected whole bricks, observing the horizontal rows and ligation rules. The height of an ordinary lintel is 4...6 rows of masonry, the length is 50 cm greater than the width of the opening. For masonry, use a solution of a grade of at least 25.
The lintels are laid out with formwork (Fig. 52, c) from 2 boards 40...50 mm thick. A layer of mortar 20...30 mm thick is spread over the formwork, into which reinforcing bars are then embedded under the bottom row of bricks of the ordinary lintel (one steel rod with a diameter of at least 6 mm for every 1/2 brick of the wall thickness, but not less than three rods to the lintel, unless the design requires other reinforcement). The ends of the rods 1 are passed beyond the edges of the opening by 250 mm (they must end with a hook), i.e. they are anchored in the masonry; Periodic profile bars do not need to be anchored.
The ends of the formwork boards rest on bricks released from the masonry; After the formwork is removed, they are cut down. Sometimes the ends of the formwork are inserted into the grooves on the slopes of the openings (after removing the formwork, the grooves are filled with bricks). If the width of the opening is more than 1.5 m, then a stand is placed under the formwork in the middle or the formwork is supported on wooden circles 3 (boards placed on edge).
In addition to plank formwork, inventory tubular supports-circles 4 are used (Fig. 52, d). They are made from two pieces of pipe with a diameter of 48 mm, inserted into a third piece of pipe with a diameter of 60 mm. When laying the pipes, the circles are moved apart so that the ends of the pipes of smaller diameter go inside the grooves left in the masonry. Two circles are placed on each opening; they can be used when window door blocks are inserted into openings. With other types of circled blocks, they can be placed only after removing the lintel formwork.
Rice. 53. Laying wedge (a), beam (b) and arched (c) lintels:
1 - direction of the supporting plane, 2 - interlocking brick, 3 - cord, 4 - square template, 5 - wedges
Wedge and beam lintels (Fig. 53, a, b) are laid out from solid ceramic or silicate bricks with wedge-shaped seams, the thickness of which at the bottom of the lintel is at least 5 mm, at the top no more than 25 mm.
Before laying the lintel, the wall is erected to the level of the lintel, simultaneously laying out its supporting part (heel) from hewn brick (the template determines the direction of the supporting plane 1, i.e. the angle of its deviation from the vertical). The masonry is laid in transverse rows on formwork supported by circles. Rows of masonry are marked on the formwork so that their number is odd, taking into account the thickness of the seam. The central brick 2 in the odd central row is called the castle brick.
Wedge and beam lintels are laid out parallel on both sides from the heel to the lock so that they are wedged in the lock by the central odd brick. The direction of the seams is controlled by a cord secured at the point of intersection of the mating lines of the supporting parts (heels).
For spans of more than 2 m, the laying of wedge lintels is not allowed.
Arched lintels (Fig. 53, c), arches and vaults are laid out in the same sequence as wedge lintels. The seams between the rows should be perpendicular to the curved line forming the lower surface of the arch and the outer surface of the masonry, widening at the top and narrowing at the bottom.
The arrangement of the rows of masonry and the beds separating them are established in accordance with the first rule of cutting masonry, since in arches and vaults the force from the load acts tangentially to the curve of the arch and the bed of the rows are perpendicular to the direction of the pressure.
Arched lintels are laid along the formwork from the heels to the lock simultaneously on both sides.
The joints of the masonry are completely filled with mortar. The upper surface of the vaults, 1/4 brick thick, is rubbed with mortar during the laying process. With a greater thickness of the vault made of brick or stones, the masonry seams are additionally filled with liquid mortar, while the upper surface of the vaults is not rubbed. The direction of the radial seams and the correct placement of each row are checked using cord 3, fixed in the center of the arch. Using a cord and a square template 4, one side of which has a shape corresponding to the curvature of the arch, the position of each row of masonry is determined and checked.
Formwork for laying vaults and arches should be lowered evenly when stripping. To do this, wedges 5 are placed under the circles, and when they are gradually weakened, the formwork is lowered.
The holding time for arched and wedge lintels in the formwork, depending on the outside temperature (in summer) and the type of masonry mortar, is 7...20 days, and for ordinary lintels - 5...24 days.
Lintels, vaults, and arches made of brick are today, rather, a tribute to the design of the building’s exterior. The installation of wedge-shaped, arched lintels allows a modern building to fit into the existing buildings of the past. Arches and vaults are an integral part of many types of stoves and fireplaces. The proposed technology for laying brick openings will help to complete the work efficiently.
Types of brick covering openings
A lintel is the covering of a door or window opening. Most Applications received reinforced concrete lintels in construction. They can span long spans and withstand heavy loads.
Brick lintels are used only for non-load-bearing walls, as they do not have sufficient strength for this. The span width should not exceed 1.7 m.
1 - private; 2 - wedge-shaped; 3 - arched; 4 - arched beam
Ordinary brick lintels are called ordinary lintels. The bricks in them are supported by reinforcement. Wedge, bow, lancet, arched, semicircular and box lintels are used as an architectural detail of facades.
1 - semicircular; 2 - lancet; 3 - box
Their variety is determined by the shape of the opening, or more precisely, the outline of its upper part. According to the principle of an arched lintel, vaults are laid out, which are the ceiling of buildings.
Before the invention of concrete ( late XIX centuries) the openings were blocked with brick lintels. It was not only a tribute to beauty. Wedge and types of arched openings held the load from the wall due to the expansion, which ensured the fan arrangement of the bricks in the masonry.
In temple architecture, arches and vaults, as a way of covering openings and rooms, over time became the canon of church architecture. Modern brick arched openings and vaulted ceilings are only an architectural solution.
The use of arched or wedge lintels is necessary when reconstructing buildings and structures of the 17th-19th centuries.
Stoves and fireplaces are still being built today in almost every country house, where arched or wedge-shaped lintels and barrel vaults are often used when constructing a stove or guardianship.
Ordinary jumpers
Ordinary lintels are made according to the principle of ordinary brickwork. It is also carried out with dressing and ensuring horizontal and vertical seams. Its difference from simple masonry is the observance of a special quality of work. Careful filling of the seams is necessary to create a joint work of all the bricks covering the opening.
Ordinary lintels, unlike ordinary masonry, not only compress under the weight of the overlying wall, but also bend, having no support in the opening. The size of the brick lintel is taken based on its bending performance in the opening. The height is 5, 6 rows of masonry. In length, the size is calculated by the width of the opening plus 500 mm on each side of it.
Due to the special importance of the design of the ceiling of any opening, the brick selected for masonry is selected, the grade of mortar used is no lower than 25. In an ordinary lintel, the brick rests on reinforcement, which is embedded in a layer of cement-sand mortar.
Reinforcement is assigned by calculation and depends on the magnitude of the load on the opening. If their values are small, the reinforcement is installed structurally from round steel with a diameter of 4-6 mm. Its quantity is one rod per half brick of the wall. The reinforcement must extend into the masonry beyond the edge of the opening by at least 250 mm. Their ends are bent upward around the brick.
1 - fittings; 2 - solution; 3 - formwork
To install an ordinary lintel, like any other, you will need a tool that is used for ordinary brickwork. To make reinforced support for bricks, it is necessary to install formwork. It can be made from boards 40-50 mm thick.
You can avoid leakage of the solution and give the bottom of the lintel a more even appearance by laying any rolled waterproofing or simple plastic film on the boards. It must be remembered that unevenness on the surface of the formwork will affect appearance the top of the opening.
A mortar layer is spread on the formwork, on which reinforcing bars are laid and embedded into it. Then a second layer of mortar is laid, which covers the reinforcement. It is important to observe the thickness of the protective layer for metal products. It is at least 3 cm.
When hardening, the solution must gain the necessary strength so that further laying of the lintel can be carried out. The period of keeping it in the formwork is at least 12 days in the summer, in the fall - at least 20 days. During periods of negative temperatures, it is necessary to observe special measures developed for winter masonry.
To support the formwork, bricks are made from the masonry, which are subsequently cut down after the mortar has gained full strength and the boards have been removed. You can make a furrow in the masonry and insert formwork into it, after removing which a brick with a masonry joint is installed in this place.
1 - formwork; 2 - brick release
Large openings (wider than 1.5 m) require the installation of racks under the formwork. You can install the support boards under the flooring on the edge for rigidity.
Wedge lintels
Wedge lintels do not require reinforced mortar support. The load-bearing capacity of such a lintel occurs due to the expansion in the wedge-shaped installation of the brick.
Exists for the option of installing wedge jumpers:
- wedge-shaped vertical joint of masonry;
- wedge-shaped brick.
In the case of a wedge-shaped seam, its thickness at the bottom is taken to be at least 5 mm, and at the top - no more than 25 mm. If wedge bricks are used, the joint in the masonry is made of the same thickness of no more than 10 mm. Wedge lintels are installed using formwork with circles.
If a window or doorway is placed with quarters, then to construct a wedge lintel you will need three circles. One is made shorter and installed at the level of the quarters, the other two - inside the opening. Longer circles are covered with formwork, which can be made from boards.
The wall is laid to the level of the upper part of the lintel with a heel (support) device. In this case, the angle of inclination of the edge of the lintel (bricks) relative to the vertical is immediately determined. Next, you need to mark all the rows on the formwork of the future floor. Their number must be odd. When calculating the design of each row, it is important to take into account the thickness of the seam.
The central brick row is inserted vertically and acts as a lock. It creates compression in the lower part of the lintel and makes it possible to withstand the overlying load without reinforcement.
1 - lock; 2 - heel
They begin laying the wedge lintel from the heels to the middle on both sides, in order to ultimately approach the central brick - the castle. You can maintain the exact direction of each seam by finding the point of intersection of the direction lines of both heels. A nail is driven into this place on the formwork and the line of each seam is determined using a rope tied to the nail.
Arched lintels, arches and vaults
The principle of constructing arched ceilings of openings and vaults does not differ from the laying of wedge lintels. The shape of the arch can be arched, lancet, semi-circular, or box-shaped. They differ in the choice of center, segment size and circle radius.
In any embodiment, the center line of the seam is perpendicular to the inner surface of the lintel or arch. The curved line is formed due to the wedge-shaped joint or wedge-shaped brick. In the case of an arched opening, the center line of the seam is a continuation of the radius of the curve.
Calculation of the arched lintel: 1 - onion arch; 2 - semicircular arch; h—arc height; s is the width of the window or door opening; r — arc radius
The thickness of the seams is taken as in wedge lintels:
- minimum 5 mm - for the bottom of the vertical seam;
- maximum - 25 mm - for the upper part.
1 - lintel brick; 2 - wedge-shaped solution; 3 - castle brick; 4 - circled
The formwork shape is made in accordance with the selected floor shape. Checking the radial direction of the seams and the correct curvature of the arches is done with a rope tied to the center of the circle of each section of the lintel. You can make a template-gon for the desired outline of a semicircle or segment.
Arches are laid out according to the principle of an arched lintel. Vaults today are erected during the construction of public buildings, churches or temples. To construct them, continuous formwork of the required shape is made. Cylindrical vaults are often laid out in a “Christmas tree”. The masonry is carried out simultaneously parallel to the axis of the arch and in rows at an angle of 45°.
Wedges are placed under the formwork, which are gradually removed when stripping the formwork to ensure its uniform lowering. Fresh masonry is very sensitive to loads. You cannot place containers with mortar on it or place bricks for masonry. This can lead to distortion of the shape of the ceiling and disruption of the bonding of the brick and mortar.
Vaults and arches of complex configuration require highly qualified mason, and it is better to entrust the work to a specialist. Having understood the intricacies of the technology of brick ceilings for openings, the construction of lintels and arches of a simple configuration will not be difficult.
Brick lintels, arches and vaults that came from the past, and today decorate the facade of the house, fencing, small architectural forms, fireplaces and stoves, harmoniously fitting into the interior or exterior of almost any architectural style.
