Any building, regardless of whether it is residential or abandoned, is subject to gradual destruction. The walls, foundation, and brick itself are deformed. The basis for such manifestations may be errors of builders during the construction of the structure, improper operation of the building, and low performance of design work. Timely elimination of such consequences will return the building to its former appearance and extend its useful life. Strengthening can help in such a situation brick walls.

Deformation of a brick wall requires reinforcement. By strengthening the masonry, the load-bearing capacity of the wall can be completely restored.

Why is integrity violated? brickwork? This may be affected by:

1. Heterogeneity of the soil composition under the building.
2. Increased load on the foundation and load-bearing elements.
3. Lack of expansion joints between parts of the structure.
4. Uneven load on the soil foundation.
5. Foundation subsidence.

Stages of deformation of brickwork

1. Tension in the structure that does not entail damage to the masonry.
2. The appearance of minor cracking in some bricks, so-called hairline cracking.
3. Connection of several clefts with vertical seams. This contributes to the delamination of the masonry.
4. Gradual deformation of the base of the wall.

Already at the first signs of such manifestations, it is important to understand the reasons and monitor the quality indicators of the laid brick. It is necessary to ensure that the external walls are tied, the height of the seams, the maintenance of a horizontal base and the filling of these gaps with the composition.

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Method of strengthening brick surfaces

Currently, reinforcement of brickwork is carried out using the following clips:

Scheme of strengthening brickwork: 1 – crack, 2 – injection holes, 3 – injection pipes, 4 – cement-sand mortar, 5 – crack filled with cement mortar.

• reinforced;
• reinforced concrete;
• compositional;
• steel.

To correctly determine the strengthening technique, you need to take into account the following factors: the condition of the wall, the reinforcing coefficient, the grade of concrete or plaster composition, and the characteristics of the load on the surface. The strength of such a structure is determined by the percentage of reinforcement with clamps. During an external inspection of the building, you can check the number of cracks, their depth and width. The use of clips in reconstruction will allow you to recreate the load-bearing capacity of the building.

When assessing the external characteristics of load-bearing components, it is important to present this picture in reality. First, the walls are cleaned of dirt, debris and washed with water. Plaster subject to deformation is completely removed. It is worth noting that it is not enough good quality cleaning the surface will lead to rapid failure of the masonry.

Along with carrying out strengthening measures with clips, it is necessary to cover the cracks with a cement composition under pressure. Such measures will enhance the load-bearing capacity of the structure. The compositions used must have high frost resistance, be sufficiently viscous, have low shrinkage rates, adhere tightly to the brick and be compressed.

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Restoration of brick partitions

For repairing brickwork, especially for getting rid of cracks, on outside The walls are installed with metal overlays. They help strengthen the structure and prevent it from collapsing further. First, the gap should be sealed with paper, and after some time, its condition should be assessed. Its integrity indicates the completion of the deformation process in the building. This means it is time for repair work. The break in the strip indicates the continuation of such destruction.

Metal overlapping elements strengthen the structure and prevent it from further deteriorating.

Therefore, it is necessary to determine the cause of this phenomenon and take certain actions to eliminate them. It is important to pay attention to the quality of the foundation; it may require strengthening.

In some cases, strengthening of masonry supports using the method of reinforcement and high-quality ligation of the structure is used. Sometimes, in order to firmly fix the walls, special corsets are used, made of reinforced concrete compositions by increasing their cross-section.

1. Dismantling of brick walls with minor defects is carried out on their own. Typically, special hand-held machines, blasting techniques and mechanical method cleaning.
2. The use of a manual method for dismantling partitions gives the right to use a pickaxe and a crowbar. The movements are carried out in this order: start at the top, gradually move down, maintaining the horizontality of the rows.
3. To dismantle a particularly strong base of the wall, take a sledgehammer, scarpel, and wedges.
4. You can dismantle a plane consisting of rubble or rubble concrete with a jackhammer, pick and crowbar.

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Carrying out repairs and restoration of brickwork

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Recreating a brick surface by joining joints

If there is a disturbance in the outer layer of the brickwork at the time of weathering, a noticeable decrease in technical characteristics ceilings and partitions lose their main purpose. Such phenomena are eliminated by plastering the joints with a cement composition.

On the eve of jointing, the brick is cleared and washed using water. After this, the seams are filled with mortar and leveled with special tools. If there are separate gaps on the lintels, they are strengthened by injecting fluid compounds into them. As an example, you can use cement, polymer cement.

Arched lintels are repaired as follows: first, the excess load is removed from them, then they are repositioned. Ordinary and wedge varieties are restored by strengthening the liners from the floors made of steel or reinforced concrete.

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Getting rid of cracks in brick floors

The presence of small gaps on the partitions of the building allows the use of concrete mixture for these purposes, but one should not forget about preliminary clearing of the wall. If the cracks are very deep and large, the damaged area should be redone.

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Restoration of areas with severe wear and tear

If the load-bearing floors are fairly worn out, this area is laid out again. As a result, the walls are completely restored to their original appearance. This method helps to completely eliminate surface imperfections.

Work order:

1. First, a small temporary fastening is created, which is located just above the area of ​​interest of the ceiling.
2. The destroyed part is dismantled and rebuilt. Here you need to use brick and mortar M100.
3. Masonry is carried out when the masonry material is completely seated. At the top, the border of the destroyed and restored wall is covered with a cement mixture of the previously indicated brand.
4. In the process of rearranging partitions, you can use steel wedges.
5. As the new wall is being built, temporary fastenings are dismantled within 50%.

1. When starting activities related to relocation, you should get rid of the reasons leading to such changes.
2. If the load-bearing floors do not require their replacement, they are re-laid after preliminary installation of temporary structures on several floors.
3. Non-permanent structures should be removed 7 days after the last tiers have been laid out.
4. Before unloading the selected area, unloading beams are laid in its upper part on both sides, their grooves are punched and sealed with a pneumatic hammer. Vertical cracks are covered with elastic cement.

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Additional options

Using a channel. Many builders use a rigid belt or channel to strengthen the structure. It helps stop the possible destruction of floors and prevents walls from stretching.

Types of rigid belts:

• local;
• fixed around the perimeter of the building;
• are common;
• used to eliminate separation of corners;
• fixed to the points of separation of two walls;
• identified at the places where faults appear.

To create such a belt, you need to take the following steps:

• First, devices are installed on one side;
• then the opposite side is repaired.

When arranging the stiffening belts, it is important to install the coupling bolts.

Reinforced clip. Restoring brickwork, eliminating cracks and preventing the occurrence of new defects is associated with the use of wall reinforcement. The coating is enhanced at the moment when reinforcement frames, rods, meshes, and reinforced concrete pilasters are connected to the work.

The reinforcing mesh is secured with anchors or through pins into the drilled holes.

Strengthening a structure with reinforcing mesh is carried out as follows: this material is fixed to a given area, on one side. It is secured in previously made holes using studs or anchor bolts. Its upper part is coated with M100 cement composition. This solution significantly improves the technical performance of the base. The plaster layer can reach a height of up to 40 mm.

Strengthen the corner points with additional rods. If the mesh mechanism is installed on one side, it is secured with bolts small sizes. Double-sided coating involves fixing with anchor fasteners with a large cross-section, up to 12 mm every 1000 mm.

Advice! To strengthen an object, you need to use design and seek help from specialists. Otherwise, even the most quality materials will not improve the situation, but will only worsen it due to the heavy load on the foundation and the entire structure.

Structural schemes for strengthening stone structures

An effective way to strengthen stone structures is to enclose the masonry in a steel or reinforced concrete frame.

The steel frame consists of vertical corners installed on the mortar at the corners of the reinforced element and clamps made of strip steel or round rods welded to the corners. The distance between the clamps should be no less than the smaller cross-sectional size and no more than 50 cm. The steel frame should be protected from corrosion by a layer of cement mortar 25-30 mm thick. To ensure reliable adhesion of the solution, the steel corners are covered with a metal mesh.

The reinforced concrete cage is made of concrete of class no lower than B12.5 with reinforcement with vertical rods and welded clamps. The distance between the clamps should be no more than 15 cm. The thickness of the clamp is determined by calculation and can be from 4 to 12 cm. Repair of damaged masonry walls, pillars, piers, foundations is carried out by the injection method, in which liquid cement or polymer is injected into the damaged masonry under pressure mortar, which helps seal cracks, pores and voids in the masonry.

Preparatory work for masonry injection includes: determining the location of wells, drilling wells and installing metal pipes in them; cleaning cracks and masonry surfaces from drilling sludge and dust; sealing all cracks by plastering with a thin layer of cement mortar. When injecting, Portland cement of a grade of at least 400 with a grinding fineness of at least 2400 cm 2 /g is used as a binder for cement and cement-polymer mortars. The solution is injected into the structure under pressure up to 0.6 MPa. Injection pipes 6-10 cm long are made from scraps gas pipes and have a thread of 5-6 turns at one end.

Repair of stone structures can be carried out by replacing damaged masonry with new one. The method of replacing structures with new ones requires the preliminary installation of temporary fastenings for the period of work, capable of absorbing the upstream loads transmitted to them. After installing temporary fastenings, it is allowed to dismantle the old masonry and create a new one using mesh reinforcement.

Repair of brick and concrete walls (Fig. 4.1) in case of destruction of masonry due to defrosting in buildings with high humidity is carried out by applying an additional layer of insulation to the outside of the wall while simultaneously installing an air gap. Additional insulation protects the wall structure from exposure to negative temperatures, and the air gap serves to remove excess moisture from the walls.

Rice. 4.1 Installation of an additional layer of insulation on the outside of the wall

Glass or mineral wool insulation and profiled sheets (steel or asbestos-cement) are attached with supporting corners to the wall using special elements. Profiled sheets are attached to the support corners with self-tapping screws. Ventilated layers are formed by the internal cavities of profiled sheets.

If the strength of the masonry weakens before the fencing is installed on the outside, it is necessary to reinforce the masonry with gunite.

Reinforcement of pillars, piers and pilasters with clips is shown in Fig. 4.2; 4.3. The load-bearing capacity of stone and brick pillars, piers, pilasters and pylons can be significantly increased by installing steel, reinforced concrete or reinforced mortar cages that create lateral compression of the masonry. Clips are installed in cases where the load-bearing capacity of pillars, piers and pilasters is insufficient during the reconstruction and addition of buildings or in case of significant damage to the masonry (cracks, crushing, chips).

Rice. 4.2 Reinforcement of pillars (piers) with clips: a - metal; b - reinforced concrete; 1- brick pillar; 2 - steel corners; 3 - strips; 4 - concrete; 5 - longitudinal reinforcement with a diameter of 6-12 mm; 6 - clamps with a diameter of 4-10 mm; 7 - new masonry, reinforced with mesh in 3 rows; 8 - welding

Rice. 4.3 Reinforcement of pilasters with clips: a - steel; b - reinforced concrete; 1 - steel corners; 2 - connecting strips (clamps); 3 - thrust washer 10-12 mm; 4 - bolt with a diameter of 18-22 mm; 5 - caulking with cement mortar; 6 - clamp with a diameter of 18-22 mm; 7 - reinforcing mesh with a diameter of 8-12 mm; 8 - concrete; 9 - concrete crackers

The steel frame consists of vertical corners installed on the mortar at the corners of the reinforced element, and clamps (transverse strips) made of strip steel or round rods welded to the corners. The distance between the clamps should be no less than the smaller cross-sectional area of ​​the element and no more than 55 cm. To protect against corrosion, the steel cage is plastered with M50-100 cement mortar 2-3 cm thick over a metal mesh. The cross-section of corners and clamps is determined by calculation. It is recommended to use corners with flanges measuring 50-75 mm and clamps made of strip steel with a cross-section of 40x5-60x12 mm or round steel with a diameter of 12-30 mm.

To obtain the effect of compressing the masonry, the gap between the masonry and the corners should be carefully sealed (caulked) with M50-100 cement mortar and compressed using tension clamps (Fig. 4.4). To tighten the nuts, tighten them with a torque wrench. The tension value is 30-40 kN.

Rice. 4.4 Reinforcement of stone pillars with metal tension clips: 1 - corners; 2 - corner segment; 3 - transverse rod; 4 - nut; 5 - washer; 6 - plaster layer; 7 - straight wedge; 8 - reverse wedge; 9 - stiffener; 10 - support corner

The reinforced concrete frame is made of concrete B 12.5 and higher with reinforcement with vertical rods with a diameter of 10-16 mm and clamps with a diameter of 6-10 mm. The distance between the clamps should be no more than 15 cm. The class of concrete should be greater than the grade of brick. The thickness of the frame is taken by calculation and can vary from 4 to 12 cm. Concreting is carried out in formwork.

Strengthening stone structures with reinforced mortar clips is done in the same way as with reinforced concrete clips. In this case, instead of concrete, M75-200 cement mortar is applied to the surface of the structures in layers of 2-3 cm manually, using a mortar pump or by shotcrete.

If the ratio of the width of the column or wall to the thickness is more than two, additional transverse links are installed in the middle, passed through the masonry at a distance of no more than two thicknesses and no more than 100 cm.

Damaged pilasters are reinforced with steel or reinforced concrete frames, as shown in Fig. 4.3. The clips should cover the pilaster on three sides. In this case, clamps with a diameter of 18-22 mm are passed through the wall. After installing the clamps, the clamps are tightened from the outside using nuts, under which steel thrust washers 10x10 cm, 10-12 mm thick, or channel cuttings are placed.

Before installing the frames, it is recommended to strengthen the masonry of pillars, piers and pilasters damaged by cracks by injecting cement or cement-polymer mortar.

Steel, reinforced concrete and mortar frames are calculated in accordance with the Guidelines for the Design of Stone and Reinforced Stone Structures (M.: Stroyizdat, 1984).

In case of local damage to the masonry of piers, pillars, pilasters (vertical or oblique cracks of short length, crushing and chipping of the masonry under the ends of the lintels in places where beams and trusses support), the installation of clips is not necessary. It is enough to tighten the damaged areas with single clamps (bandages) made of 6x60 (80) mm strip steel (Fig. 4.5), and inject the damaged masonry with cement mortar under pressure.

Rice. 4.5 Reinforcement of the wall with a steel clamp: 1 - clamp made of strip steel 6x60 (80) mm; 2 - jumper; 3 - sealing with M100 cement mortar; 4 - crack; 5 - pier; 6 - welding

The solidity and bearing capacity of stone structures damaged by cracks (walls, pillars, piers, vaults, etc.) can be restored by injecting (injecting) cement, cement-polymer and polymer solutions into the masonry under pressure up to 0.6 MPa using manual or mechanical pumps. The solidity and strength of the masonry increases due to the gluing effect of the mortars and their filling of voids and cracks in the masonry.

The load-bearing capacity of brickwork damaged by cracks under compression after injection with cement and cement-polymer mortar is calculated as a monolithic masonry in accordance with SNiP P-22-81 “Stone and reinforced masonry structures” multiplied by the coefficients m k: when injected with cement and cement-polymer mortars m k =1.1; the same, with polymer solutions m k =l.3; when injecting individual cracks that arose under the influence of temperature, shrinkage, and uneven settlement of foundations m k = 1.

The load-bearing capacity of masonry walls and foundations can be significantly increased by laying (new masonry) or overlaying walls on one or both sides. The walls and foundations are laid from the same materials as the main wall.

To increase the load-bearing capacity, the masonry is reinforced with meshes and frames. The thickness of the pad, determined by calculation, can vary from 12 to 38 cm or more. To ensure collaboration with the main masonry, the butt must have a constructive connection with the main masonry (banding, dowels, pins, through rods, etc.).

The concrete lining of the walls is made of heavy or light concrete B7.5-15, reinforced with mesh with a diameter of 4-12 mm (Fig. 4.6). The thickness of the concrete layers, determined by calculation, ranges from 4 to 12 cm. Concrete is laid to the height of the floor in formwork with vibration or layer-by-layer concreting using the shotcrete method.

To increase the adhesion of concrete to masonry, horizontal and vertical seams are first cleared, the surface of the masonry walls is notched and washed with water.

Reinforcing mesh is attached to steel pins with a diameter of 5-10 mm, embedded in Ml00 cement mortar into masonry joints or holes drilled with an electric drill.

For walls made of bricks and stones of regular shape, the depth of embedding the pins is 8-12 cm, the spacing of the pins along the length and height is 60-70 cm, with a staggered arrangement - 90 cm.

When laying double-sided concrete on walls and foundations made of rubble masonry, through connecting rods with a diameter of 12-20 mm are installed. The spacing of the rods for good adhesion of concrete to rubble masonry is 1 m.

The load-bearing capacity of walls and foundations reinforced with concrete is calculated as for multilayer walls with a rigid connection between layers in accordance with the Manual on the design of stone and reinforced masonry structures (M., 1987) to SNiP P-22-81.

Rice. 4.6 Reinforcement of walls with concrete: 1 - wall; 2 - floor slabs; 3 - nabetonka; 4 - pins with a diameter of 10 mm; 5 - reinforcing mesh with a diameter of 6-8 mm

Pillars and piers are repositioned in the following cases: when structures are reinforced with clips, injection, etc. economically and technically impractical (significant damage or weakening of the section, emergency condition of the masonry); during the superstructure and reconstruction of buildings, when the specified methods of strengthening are insufficient; if it is necessary to preserve the architectural appearance of the building.

The pillars and piers to be re-laid are dismantled after installing temporary fastenings for the duration of the work, which must be designed to absorb the loads acting on the pillar or pier being replaced. It is recommended to replace the walls one at a time.

Temporary fastenings of pillars and piers are recommended to be made in the form of wooden or metal racks on wedges, installed in close proximity to the structure being dismantled (Fig. 4.7), or by partially or completely temporarily filling openings on both sides of the pier.

Rice. 4.7 Strengthening damaged walls with racks and unloading them from the weight of the floors: 1 - lining; 2 - stand; 3 - wedges; 4 - lying down; 5 - jumper; 6 - beam

When dismantling piers and pillars, safety measures should be observed while constantly monitoring the condition of the racks and their sub-blades. It is not recommended to use pneumatic hammers to dismantle masonry of damaged walls.

For laying new pillars and piers, materials of increased strength are used: stone materials (brick, concrete and natural stones) grade 100 and higher on cement mortar grade 100-150. If necessary, the masonry is reinforced with steel mesh placed in horizontal joints.

To ensure a tight fit of the new masonry to the old one, the top of the new masonry is not brought closer to the old one by 3-5 cm, followed by carefully caulking the gap with dense (“dry”) cement mortar of grade 100-150. Temporary fastenings are dismantled when the new masonry solution reaches 50% of its design strength.

The surface layers and wall cladding are restored as follows. Weathered, defrosted and peeled layers of masonry or wall cladding are removed and replaced with new masonry (cladding), structurally connected to the old undamaged masonry. It is not allowed to erect new masonry or cladding without a constructive connection with the old one. New masonry (cladding) is made from the same or more durable and frost-resistant materials using M50-100 cement mortar. The structural connection of the new and old masonry is ensured by ligating the bonded rows (if possible) or using steel mesh and frames made of rods with a diameter of 3-4 mm or “whiskers” made of knitting or annealed wire, embedded in the horizontal seams of the new masonry every 60-90 cm along height (multiples of row height). Nets, frames and “whiskers” are attached to steel pins with a diameter of 5-8 mm (Fig. 4.8). The pins are driven or embedded with M100 cement mortar into the masonry seams to a depth of 6-12 cm. “Whiskers” can be embedded into the masonry seams with cement mortar without pins (loops).

The vertical seam between the old and new masonry (cladding) is filled with cement mortar. It is recommended to replace damaged or peeled layers of masonry and cladding sequentially in sections no longer than 5 m in accordance with the PPR and in compliance with safety measures.

Depending on the structural and architectural requirements for the solidity and facial texture of the external surfaces (facades) of the walls, it is recommended to seal cracks by injection and caulking with cement mortar, laying bricks or sealing with concrete and by lining the masonry surfaces with brick (stone).

Injection of cracks with an opening of up to 4 mm is performed by injecting cement or cement-polymer mortar under pressure. When cracks open more than 4 mm, sealing cracks with mortar can be done using a mortar pump or a pneumatic blower.

Rice. 4.8 Mounting brick cladding to the old masonry with pins: 1 - old masonry; 2 - facing; 3 - steel pin or nail with a diameter of 5-8 mm; 4 - “whiskers” made of wire or reinforcing mesh (dotted line) with a diameter of 3-4 mm; 5 - cement mortar

Sealing (caulking) cracks with cement mortar is recommended for cracks opening more than 3 mm in cases where complete filling of cracks with mortar is not necessary. Caulking with M100 cement mortar is carried out to a depth of 2-4 cm on each side after clearing and washing the cracks with water.

Large cracks (fractures) with an opening of more than 5 cm are laid with bricks using M50-100 mortar with or without ligation with the main masonry, or the cracks are sealed with concrete (mortar) B3.5-7.5 on light aggregates.

Filling cracks and breaks in walls is carried out when it is necessary to preserve the facial texture of brick, stone or cladding. In this case, the wall masonry along the length of the crack is dismantled to a depth of half a brick and a width of at least one brick (stone), followed by filling the cracks with a new brick in a dressing with the old one (Fig. 4.9).

In walls and partitions with a thickness of 25 cm or less, the damaged masonry in the crack zone is dismantled and replaced throughout the entire thickness of the wall. Walls and partitions that have longitudinal delamination of the masonry (longitudinal cracks) must be tightened in the transverse direction with bolts and washers. Cracks are sealed by injecting cement or cement-polymer mortar, as described above. The diameter of the coupling bolts is at least 16 mm; the pitch of the bolts along the length and height is 60-70 cm, when the bolts are staggered - 90 cm.

Rice. 4.9 Sealing cracks with dismantling old masonry

Tensile reinforcement steel rods and belts of walls and floors of single-story and multi-story buildings damaged by cracks (Fig. 4.10, 4.11) are carried out in order to: restore or increase the solidity, spatial rigidity of buildings and the strength and stability of walls and floors; stopping the development of wall deformations out of plane (tilts, bulging); reducing or stopping the development of cracks in walls and ceilings with uneven settlements of foundations, temperature and humidity influences and with different rigidity and load of adjacent walls.

The rods must have a tensioning device (couplings, nuts) or be strained by thermal heating using blowtorches or an autogen. The tension increase should be 30-50 kN. Tension is controlled special devices(strain gauges, strain gauges, indicators) or tapping (when struck, the tense cord should produce a high-pitched sound). The tension is carried out simultaneously along the entire contour of the building after sealing the cracks with cement mortar under pressure. The distance between the strands is recommended to be 4-6 m, so that the wall area is no more than 20 m 2 per strand.

Rice. 4.10 Fastening walls with metal ties at the floor level: a - inside the building; b - outside the building; c - section; d - option of laying strands in a fine; 1 - cord; 2 - tension coupling; 3 - metal lining; 4 - channel No. 16-20; 5 - corner; 6 - cement mortar grade 100

Rice. 4.11 Fastening a bulging wall with metal ties: 1 - wall; 2 - cord; 3 - tension coupling; 4 - traverse from channel No. 14-16; 5 - lining

IN multi-storey buildings The ties outside and inside the premises are installed at the level of the top of the floors. In one-story industrial buildings, ties are installed along the axes of trusses or load-bearing beams in the immediate vicinity of their supports and secured to them to prevent sagging.

When strengthening stone walls from the outside with belts (Fig. 4.10), the ties are laid on the surface of the walls in grooves with a cross-section of 70x80 mm, cut into the masonry, which, after tensioning the ties, are sealed with M100-150 cement mortar.

The end stops of the strands are made in the form of metal plates 10x10-15x15 cm with a thickness of 10-12 mm or from sections of channels. The ends of the rods (strands) must be threaded with a nut.

In the absence of dressing or formation vertical cracks at the junction of external and interior walls The solidity of the masonry can be restored by installing prestressed clamps made of rods with a diameter of 20-24 mm and a length of 1.5-2 m at the level of the top of the floors (Fig. 4.12).

The clamps are anchored into the transverse walls using sections of angles or channels. The clamps are tensioned by tightening the nuts. Cracks or gaps between walls are sealed with cement mortar under pressure.

Local reinforcement of corners of buildings and individual sections of walls damaged by cracks can be performed using double-sided lining (banding) metal strips with a cross section of 6x80-10x100 mm or channels No. 14-20, tightened with bolts with a diameter of 16-20 mm (Fig. 4.13).

Damaged by cracks or destroyed, ordinary or wedge lintels of openings are re-laid or reinforced with steel beams made from channels. The beams are laid in grooves cut out on both sides of the wall and tightened with bolts or clamps (Fig. 4.14). After installation, metal beams are covered with mesh and plastered with M50-100 cement mortar.

Depending on the degree of damage, reinforced concrete lintels are repaired (strengthened) or replaced with new ones. When replacing or repositioning, the lintels on which beams or floor slabs rest must be completely unloaded by placing temporary fastenings in the form of racks or frames under the supports of the beams and slabs (see Fig. 4.7). Racks and frames must be installed on wedges.

Steel ties, beams, strapping, washers, clamps exposed to atmospheric influences or located in rooms with damp and wet conditions must have anti-corrosion protection.

Rice. 4.12 Strengthening with steel ties the intersection of brick walls weakened by a crack or seam: 1 - 20 mm diameter tie; 2 - washer 75x75x8; 3 - crack injected with M100 cement mortar; 4 - corner or channel; 5 - fine lined with brick

Rice. 4.13 Angle gain metal beams 1 - metal beams No. 16-20; 2 - coupling bolts with a diameter of 16-20 mm

Rice. 4.14 Strengthening ordinary and wedge lintels 1 - masonry; 2 - channel; 3 - bolt; 4 - plaster on mesh

Previous

Quite often, buildings with brick walls require a range of work such as repairs or complete restoration.

Joining seams

Strengthening brickwork can be done in several ways, which depends on the causes of deformation and the nature of the damage.

The main reasons for such deformations lie in the following:

• Design errors: insufficient depth of the building foundation; uneven settlement, the appearance of stresses in the walls, discrepancy between the existing loads and the calculated ones, any deformations of beams and ceilings; use of warm solutions; violations in the spatial rigidity of the composition;
• Poor operation: foundation subsidence; waterlogging of the wall; leveling the mortar, in which it is driven deep into the masonry;
• Production errors: punching an opening with violations; lateral buckling of masonry; improper plastering; poor-quality dismantling of floors; laying beams without the use of distribution plates;
• Poor quality design: increasing the number of storeys without carrying out all the calculations; improper redistribution of loads; lack of developments regarding the condition of the soil at construction sites.

At the same time, there are many ways to correct such deformations: jointing, relaying, complete restoration, strengthening of floors, beams, supports, increasing and redistributing load-bearing capacity and much more.

Methods and stages of work to strengthen masonry

Joining seams

Joint jointing of brickwork is usually necessary when significant weathering of the mortar occurs. This can greatly deteriorate the thermal mechanical properties of the wall, reducing the load-bearing capacity by fifteen percent.

Before starting work, all damaged seams are washed with water, then they are filled with fresh solution and smoothed. After drying, you can begin painting.

Jumper reinforcement

Quite often work is required to disassemble or repair old brick lintels. If there are single shallow cracks, then they can simply be filled with a solution under pressure. However, in cases where the damage is large enough to threaten integrity and safety, it is necessary to take measures such as dismantling the brickwork and restoring it.

Sometimes arched floors with regular and wedge lintels are simply reinforced with the help of reinforced concrete beams, which are installed using the method of supplying them under the lintels themselves.

Strengthening purlins and supports

If cracks appear under supports, racks, or purlins, it is necessary to take measures to unload them up to the actual load-bearing capacity of the masonry itself.

To do this, install metal plates or spacer reinforced concrete slabs, which take on part of the load. In some cases, it is necessary to completely disassemble and install new masonry.

Repairing Weak Points

If there are cracks on the walls up to 4 mm wide, they can be restored by injecting cement mortar. In case of significant deep and through cracks with an opening of 4 mm or more in the damaged area, this area is re-laid. In this case, a solution of grade 25 is used when dressing with old, undamaged masonry.

If the wall is of significant thickness, it is necessary to carry out work to completely restore it (in case of extensive through damage).

Replacement of some areas

Strengthening the masonry may require replacing some areas that are quite severely deformed. These may be some parts of the walls that have lost their load-bearing capacity, as well as deep cracks and chips that lead to subsidence of a section of the wall.

In order to make a replacement, temporary fastenings are installed above the deformed areas. Damaged areas with defects are completely re-laid using mortar grade 100. Laying is carried out when individual bricks are completely seated.

For transfer load-bearing walls without dismantling the floors, multi-tiered temporary supports are installed that transfer loads from deformed areas. Such fastenings cannot last longer than five days.

Before starting work, it is necessary to install unloading beams, which are laid from the weakest areas. All vertical gaps are filled using plastic cement mortar, and on top - with hard, greasy cement. Having strengthened the areas, you should wait until the solution hardens. Only then can finishing be carried out.

Strengthening the walls

If necessary, reinforcement brick walls The following types of work are performed:

• Dismantling window and other openings;
• Temporary supports for external scaffolding are being strengthened;
• The higher ceilings are suspended in the case where the weakening occurs over an area of ​​more than 25 percent. At the same time, pillars, partitions, and other elements are repositioned, and the necessary repairs are made;
• The masonry is dismantled, furrows are punched with a jackhammer, damaged areas are cut down, which is carried out using a reinforced concrete clip;
• Construction of a special metal frame;
• Stripping of all monolithic structures;
• Complete dismantling of all installed temporary fastenings;
• Plastering and subsequent painting of the walls.

Also, new masonry one brick thick can be laid, which is tied with the old masonry every three to four bricks. In this case, special grooves are made in front of the device to ensure the reliability of the structure.

Complete re-lining of the walls

Strengthening masonry with reinforcing mesh

When strengthening brickwork, sometimes a complete re-lining of the walls is required. In this case, first you need to unload the wall, for which temporary fastenings and supports are installed on both sides, under the ceilings, a system of crossbars and racks with trays. Afterwards, you can begin disassembling and full or partial relaying, which is carried out using cement mortar.

To increase strength and load-bearing capacity, reinforcing wire mesh is usually used. Reinforcement is also carried out using a reinforced concrete frame, which is laid directly on the masonry. After disassembly window openings quarters are hammered out, then reinforcement and formwork are installed around the perimeter of the opening, and concreting is done. In order to improve traction, furrows are punched every three to four rows of brickwork. Their depth varies, it all depends on the degree of damage.

After the formwork is removed, the walls are plastered; for interior spaces, a special layer of warm mortar is applied to the surface directly over the plaster.

Also, for reinforcement, a metal corset is used, for which the corners are cut off and in their place vertical metal corners are mounted to the entire height of the wall. Next, furrows are made along the surface with a depth of 2 cm at a distance of 30-50 cm. Metal plates with a width of 4-6cm are placed in them. At the same time, they are welded at the ends to the corners. On the corners themselves, tubercles are welded in a checkerboard pattern.

In some cases it is possible to use metal mesh, the surface of which is plastered after work.

Increased wall stability

Reinforcement of brickwork is carried out using ties made of strip or square steel or using steel channels, which are installed in the walls through pre-drilled holes.

After this, vertical linings are strengthened on the sides of the building, and the tie is made by tightening the nuts at the ends. The final tension is carried out using lanyards, i.e. couplings with internal double thread. This is carried out in the middle part of the entire length of the banner, which consists of two individual parts. A high-quality screed is ensured only when there are no sags, and when lightly tapped, they all emit a high-pitched sound, very clear.

Results

After all the fasteners are installed, the holes and cracks in the brick wall are carefully sealed using prepared cement mortar, and particularly weak areas are re-positioned. After completion of work, all metal fasteners are painted with simple oil paint.

When reconstructing residential buildings with masonry walls, there is a need to restore the load-bearing capacity or strengthen the masonry elements due to increased loads from the floors being built on. During long-term operation of buildings, signs of destruction of piers, pillars and masonry walls are observed as a result of uneven settlement of the foundations, atmospheric influences, roof leaks, etc.

The process of restoring the bearing capacity of masonry should begin by eliminating the main causes of cracking. If this process is facilitated by uneven settlement of the building, then this phenomenon should be eliminated using known and previously described methods.

Before acceptance technical solutions When strengthening structures, it is important to assess the actual strength of load-bearing elements. This assessment is carried out using the method of destructive loads, the actual strength of the brick, mortar, and for reinforced masonry - the yield strength of steel. In this case, it is necessary to fully take into account the factors that reduce the load-bearing capacity of structures. These include cracks, local damage, deviations of the masonry from the vertical, disruption of connections, support of slabs, etc.

As for strengthening brickwork, the accumulated experience of reconstruction work allows us to identify a number of traditional technologies based on the use of: metal and reinforced concrete frames, frames; on the injection of polymer-cement and other suspensions into the body of the masonry; on the installation of monolithic belts along the top of buildings (in cases of superstructure), prestressed ties and other solutions.

In Fig. 6.40 shows typical design and technological solutions. The presented systems are aimed at comprehensive compression of walls using adjustable tension systems. They are performed openly and closed types, in external and internal locations, are provided with anti-corrosion protection.

Rice. 6.40. Structural and technological options for strengthening brick walls
A- diagram of strengthening the brick walls of the building with metal strands; b ,V,G- nodes for placing metal strands; d- layout diagram of a monolithic reinforced concrete belt; e- the same, with cords with centering elements: 1 - metal cord; 2 - tension coupling: 3 - monolithic reinforced concrete belt; 4 - floor slab; 5 - anchor; 6 - centering frame; 7 - support plate with hinge

To create the required degree of tension, turnbuckles are used, access to which must always be open. They allow additional tension to be produced as the strands lengthen as a result of temperature and other deformations. Compression of brick wall elements is carried out in places of greatest rigidity (corners, junctions of external and internal walls) through distribution plates.

To uniformly compress the masonry walls, a special design of the centering frame is used, which is hinged on the support-distribution plates. This solution ensures long-term operation with fairly high efficiency.

The locations of the tie rods and centering frames are closed various kinds belts and do not violate general form facade surfaces.

For elements of walls, piers, pillars that have damaged brickwork, but have not lost stability, local replacement of the masonry is carried out. In this case, the brand of brick is taken to be 1-2 units higher than the existing one.

The work technology provides for: installation of temporary unloading systems that absorb the load; dismantling fragments of damaged brickwork; masonry device. It must be taken into account that the removal of temporary unloading systems should be carried out after the masonry has gained strength of at least 0.7 R CL. As a rule, such restoration work is carried out while maintaining design diagram building and actual loads.

Techniques for restoring unplastered brickwork are very effective when it is necessary to maintain the original appearance of facades. In this case, the bricks are very carefully selected according to color scheme and sizes, as well as seam material. After restoration of the masonry, sandblasting is carried out, which makes it possible to obtain updated surfaces where new areas of the masonry do not stand out from the main body.

Due to the fact that stone structures perceive mainly compressive forces, the most effective way their reinforcement is the installation of steel, reinforced concrete and reinforced cement cages. In this case, the brickwork in the cage operates under conditions of all-round compression, when transverse deformations are significantly reduced and, as a result, resistance to longitudinal force increases.

The design force in the metal belt is determined by the dependence N= 0,2R KJl × l × b, Where R KJl- design chipping resistance of the masonry, tf/m 2 ; l- length of the section of the reinforced wall, m; b- wall thickness, m.

To ensure normal operation of brick walls and prevent further opening of cracks, the initial stage is to restore the bearing capacity of foundations using reinforcement methods that eliminate the occurrence of uneven settlements.

In Fig. 6.41 shows the most common options for strengthening stone pillars and piers with steel, reinforced concrete and reinforced cement cages.

Rice. 6.41. Reinforcement of pillars with steel frames (a), reinforced frames (b), meshes and reinforced concrete frames ( V,G) 1 - reinforced structure; 2 - reinforcement elements; 3 - protective layer; 4 - panel formwork with clamps; 5 - injector; 6 - material hose

The steel frame consists of longitudinal corners for the entire height of the reinforced structure and transverse strips (clamps) made of flat or round steel. The pitch of the clamps is taken to be no less than the smaller cross-sectional size, but not more than 500 mm. To enable the cage to work, gaps must be injected between the steel elements and the masonry. The solidity of the structure is achieved by plastering with high-strength cement-sand mortars with the addition of plasticizers that promote greater adhesion to masonry and metal structures.

For more effective protection A metal or polymer mesh is installed on the steel frame, along which a solution 25-30 mm thick is applied. For small amounts of work, the solution is applied manually using a plastering tool. Large volumes of work are performed mechanized with the supply of material by mortar pumps. To obtain a high-strength protective layer, shotcrete and pneumatic concrete installations are used. Due to the high density of the protective layer and high adhesion with masonry elements, the joint work of the structure is achieved and its load-bearing capacity is increased.

The construction of a reinforced concrete jacket is carried out by installing reinforcing mesh around the perimeter of the reinforced structure and fastening it through clamps to the brickwork. Fastening is carried out by using anchors or dowels. The reinforced concrete frame is made from a fine-grained concrete mixture of at least class B10 with longitudinal reinforcement of classes A240-A400 and transverse reinforcement - A240. The pitch of the transverse reinforcement is taken to be no more than 15 cm. The thickness of the cage is determined by calculation and is 4-12 cm. Depending on the thickness of the cage, the technology of work production changes significantly. For frames up to 4 cm thick, concrete application methods are shotcrete and pneumatic concrete. Final finishing surfaces is achieved by installing a plaster covering layer.

For frames up to 12 cm thick, inventory formwork is installed around the perimeter of the reinforced structure. Injection tubes are installed in its shields, through which a fine-grained concrete mixture is injected under a pressure of 0.2-0.6 MPa into the cavity. To increase adhesive properties and fill the entire space, concrete mixtures are plasticized by introducing superplasticizers in a volume of 1.0-1.2% of the cement mass. Reducing the viscosity of the mixture and increasing its permeability is achieved by additional exposure to high-frequency vibration through contact of the vibrator with the jacket formwork. The pulse mode of supplying the mixture gives a fairly good effect, when short-term impacts high blood pressure provide a higher velocity gradient and high permeability.

In Fig. 6.41, G given technology system carrying out work by injecting a reinforced concrete cage. The formwork is installed to the full height of the structure, ensuring a protective layer of reinforcement filling. Concrete injection is carried out in tiers (3-4 tiers). The process of finishing the concrete supply is recorded by control holes on the opposite side from the injection site. For accelerated hardening of concrete, systems of thermoactive formwork, heating wires and other methods of increasing the temperature of hardening concrete are used. Dismantling of the formwork is carried out in tiers when the concrete reaches its stripping strength. Hardening mode at t= 60 °C ensures stripping strength during 8-12 hours of heating.

Reinforced concrete cages can be made in the form of elements of permanent formwork (Fig. 6.42). In this case, the outer surfaces can have a shallow or deep relief or a smooth surface. After installing permanent formwork and fastening its elements, the space between the reinforced and enclosing structure is sealed. The use of permanent formwork has a significant technological effect, since there is no need to dismantle the formwork, and most importantly, the finishing cycle of work is eliminated.

Rice. 6.42. Strengthening pillars using architectural concrete cladding formwork 1 - reinforced structure; 2 - reinforced frame; 3 - cladding elements; 4 - monolithic concrete

Most effective permanent formwork Thin-walled elements (1.5-2 cm) made of dispersed reinforced concrete should be considered. To engage the formwork in the work, it is equipped with protruding anchors, which significantly increase adhesion to the concrete being laid.

The design of mortar clips differs from reinforced concrete ones in the thickness of the applied layer and composition. As a rule, plaster coatings are used to protect the reinforcing mesh and ensure its adhesion to the brickwork. cement-sand mortars with the addition of plasticizers that increase physical and mechanical characteristics. The technology of construction processes is practically no different from performing plastering work.

To ensure the joint operation of the frame elements along its length, which exceeds 2 or more times the thickness, it is necessary to install additional transverse links across the masonry section. Strengthening brickwork can be done by injection. It is carried out by injecting cement or polymer cement mortar through pre-drilled holes. As a result, the monolithic nature of the masonry is achieved and its physical and mechanical characteristics are increased.

Quite stringent requirements are imposed on injection solutions. They must have low water separation, low viscosity, high adhesion and sufficient strength characteristics. The solution is injected under pressure up to 0.6 MPa, which provides a fairly wide penetration zone. Injection parameters: the location of the injectors, their depth, pressure, composition of the solution in each specific case are selected individually, taking into account the cracking of the masonry, the condition of the seams and other indicators.

The strength of masonry reinforced by injection is assessed according to SNiP II-22-81* “Stone and reinforced masonry structures”. Depending on the nature of the defects and the type of injected solution, correction factors: tk = 1.1 - in the presence of cracks from force effects and when using cement and polymer-cement mortars; tk= 1.0 - in the presence of single cracks from uneven settlements or in the event of a breakdown in the connection between jointly working walls; tk = 1.3 - in the presence of cracks from force effects during the injection of polymer solutions. The strength of the solutions should be in the range of 15-25MPa.

Strengthening brick lintels is a fairly common phenomenon, which is associated with a decrease in the load-bearing capacity of spacer masonry due to weathering of seams, adhesion failure and other reasons.

In Fig. Figure 6.43 shows design options for strengthening jumpers using various types of metal plates. They are installed by punching grooves and holes in the brickwork and are subsequently cemented with cement-sand mortar over a mesh.

Rice. 6.43. Examples of strengthening lintels of brick walls A ,b- by placing linings made of angle steel; V ,G- additional metal jumpers made of channel: 1 - brickwork; 2 - cracks; 3 - corner linings; 4 - strip overlays; 5 - anchor bolts; 6 - channel linings

To redistribute forces on reinforced concrete lintels due to increased loads on the floors, metal unloading belts are used, made of two channels and united by bolted connections.

Strengthening and increasing the stability of brick walls. The reinforcement technology is based on creating an additional reinforced concrete jacket on one or both sides of the wall (Fig. 6.44). The technology of the work includes the processes of preparing and cleaning the surface of the walls, drilling holes for anchors, installing anchors, attaching reinforcing bars or mesh to the anchors, and monolithization.

As a rule, for fairly large volumes of work, a mechanized method of applying cement-sand mortar is used: pneumatic concrete or shotcreting, and less often manually. Then, to level the surfaces, a grout layer is applied and subsequent operations related to finishing the wall surfaces are performed.

Rice. 6.44. Strengthening brick walls with reinforcement A- separate reinforcement bars; b- reinforcement cages; V- reinforcing mesh; G- reinforced concrete pilasters: 1 -reinforced wall; 2 - anchors; 3 - fittings; 4 - plaster or shotcrete layer; 5 - metal cords; 6 - reinforcing mesh; 7 - reinforced frame; 8 - concrete; 9 - formwork

An effective method of strengthening brick walls is the installation of reinforced concrete one- and two-sided racks in grooves and pilasters.

The technology for installing double-sided reinforced concrete racks involves the formation of grooves to a depth of 5-6 cm, drilling through holes along the height of the wall, fastening the reinforcement frame using ties and subsequent monolithization of the resulting cavity. For grouting, cement-sand mortars with plasticizing additives are used. A high effect is achieved when using mortars and fine-grained concrete with preliminary grinding of cement, sand and superplasticizer. In addition to great adhesion, such mixtures have the property of accelerated hardening and high physical and mechanical characteristics.

When constructing one-sided reinforced concrete pilasters, the installation of vertical grooves is required, in the cavities of which anchor devices are installed. The reinforcement cage is attached to the latter. After its placement, the formwork is installed. It is made from separate plywood panels, united with clamps and attached to the wall with anchors. Fine-grained concrete mixture is pumped using pumps in layers through holes in the formwork. A similar technology is used for double-sided installation of pilasters with the difference that the process of fastening the formwork panels is carried out using bolts that cover the thickness of the wall.

Sometimes walls, even those made of brick or reinforced concrete slabs, fall into disrepair. And there can be many reasons for this: fire, time, the premises have not been inhabited for a long time, soil subsidence, design errors, the appearance of an unplanned load. The degree of damage to walls varies, and the progress of work required to reconstruct or strengthen them depends on it.

Gain Features

Before starting work on strengthening and repair work, it is necessary to establish the degree of damage and, only then, begin work.

There are four levels of damage:

1. weak (up to 15% of the wall surface is damaged);
2. medium (up to 25% of the surface is damaged);
3. strong (up to 50% of the surface is damaged);
4. destroyed walls - more than 50% damage.

Advice. To determine the level of damage to the walls, or the speed of movement of cracks, you need to install beacons made of plaster (for internal walls) or cement (for external walls).

Cracks on external walls can change their width depending on the time of year: in winter they narrow, and in summer they widen.

Beacons are installed using the following technology: the surface of the wall where the beacons will be installed is cleaned and moistened. Strips of cement or gypsum are applied to it with a spatula (thickness 10*4*0.8 cm).

Advice. The thinner the beacon, the more accurately you can determine the speed of movement of the crack. It’s also better to install several beacons along the length of the crack.

After the beacons have dried, they are marked: a line is drawn along the beacon with a pencil, an observation notebook is kept, and the date of installation of the beacon is written down. To complete the picture, it is necessary to observe the lighthouse observers every day. With further growth of the crack, the beacon will be damaged (broken), and with further observation, you can find out the speed of its movement.

Strengthening with a strong foundation

The appearance of cracks was not due to design errors or improper foundation laying. There are several ways to eliminate them.

First way. The depth of the cracks is less than 5 mm. In this case, fill with cement mortar or warm plaster with polystyrene. First, the crack is thoroughly cleaned and moistened, after which it is filled with fresh solution.

Second way. The depth of the cracks is more than 5 mm. For good result metal staples are used.

Strengthening brick walls in this case it happens in the following order:

• the crack is cleaned and moistened;
• filled with a solution of cement and sand;
• along the crack at some distance from it, holes are drilled with a depth of 11 cm, a diameter of 2 cm, a step of 15-20 cm;
• the grooves serve as the basis of the brackets, the depth of which is 4 cm and the width is 3 cm (the grooves are attached with the mixture that was used to seal the crack);
• strengthen the staples.

Important. In order for the staples to serve for a long time, they must be processed and plastered. The same applies to gratings for strengthening walls.

Third way. For deep or through cracks, metal bridges are used (they are rigidly bolted on both sides of the crack), and then the damaged area is replaced.

Since metal conducts both current and cold well, it is necessary to insulate the walls along with restoration work.

Strengthening with cords

They are used if the verticality of the walls is disrupted with their subsequent collapse. For screeds, round reinforcement (25-30 mm in diameter) is used; they are screwed either to each other in the corners or to grooves that are installed at the joints of the walls (the second option is more reliable).

If the damage to the walls is more severe, then install clips from various materials:

1. reinforced;
2. reinforced concrete;
3. compositional;
4. steel.

This is what a heavy weight looks like

The principle of strengthening walls is approximately the same: first, metal corners are installed and attached to the walls, then a mesh is made from various materials. The cells are attached to the wall with anchors (10-12 mm), or the connections are welded, or they are fastened to a metal mesh. After this, the mesh must be plastered with a cement mixture.

Reinforced concrete structures can also be reconstructed or strengthened. There are two types of such work: restoration of individual areas, or replacement of the protective layer (in whole or in part).

For partial restoration, use cement putty, having previously cleaned and moistened the surface. If it is necessary to carry out a major reconstruction or replacement of the protective layer, it is better to use gunite. If the structure is load-bearing, then the thickness of the protective layer is increased to 3 cm, and if it is not working, then to 2 cm.

Important. Before starting restoration work, it is necessary to clean the protruding fittings from rust.

Strengthening an opening in a wall - features of the process

Strengthening the opening

The walls are strengthened by dismantling part of the masonry and replacing it with a new one, or by inserting a steel plate or reinforced concrete slab gasket To carry out this work, support beams are installed strictly vertically in the opening.

Then they carefully dismantle part of the masonry, or insert a steel or reinforced concrete slab. Grooves are installed in the recess and grooves are attached to them, to which, in turn, a steel plate or reinforced concrete slab is attached. After its installation, it is covered with cement mortar. After the latter has completely dried, the supporting structure is disassembled.

The completion of the work is the complete restoration of the structures.