Development of functional literacy of students in the classroom. Formation of functional literacy of younger students in the classroom in primary school

Inspection of building walls

The walls of buildings are examined by the following methods:

visually (when their general condition is judged by the nature of the cracks and the curvature of the lines of the facades);
appliances;
by opening and sampling.

When examining walls, the following parameters and characteristics are determined:

wall dimensions;
distance between axles;
axle offset;
masonry quality;
strength of brick, mortar, concrete;
waterproofing condition; wall moisture;
heat-shielding and soundproofing properties;
presence of defects.

Special attention during examination brick walls refer to:

cracks in piers and lintels; vertical deviation;
distortions;
deviation of dimensions from design; poor filling of joints with mortar;
buckling;
the presence of destroyed and weakened areas;
breaking bonds between walls;
corrosion of embedded parts, bricks and mortar;
peeling of cladding and plaster;
lack of distribution pads under the beams;
insufficient strength of materials;
poor-quality waterproofing, thermal insulation, sound insulation;
improper reinforcement of masonry;
moistening the walls;
freezing corners;
design flaws.

When examining large-panel walls, the following can be noted:

cracks on the surface of the panels;
difference between the dimensions of the panels and the design ones;
rupture of bonds between panels of internal and external walls;
corrosion of embedded parts at joints;
destruction of joints;
destruction of the protective layer;
incorrect reinforcement;
unsatisfactory heat-shielding and sound-proofing qualities;
increased water and air permeability;
design flaws in the joints, installation defects.

wall survey they start with identifying the structural scheme of the building, the purpose of the walls (enclosing, load-bearing, self-supporting), the strength characteristics of the material, the types of connection of walls (wall panels) with other load-bearing structures: foundations, columns, ceilings, etc.
With the help of geodetic instruments, wall deviations from the vertical, local buckling, horizontal joints and seams are determined. Measure the thickness of the joints and cracks. Relative horizontal deviations (to the floor height) for brick and reinforced concrete walls should not exceed 1/500, lined with natural stone 1/700, stained-glass windows 1/1000. The moisture content of the wall material is found by sampling from different layers of the wall structure, in case of its multilayering. Samples are numbered, weighed and placed in a thermostat, where they are dried at a temperature of (110 ± 5)°C to constant weight. Compare the moisture content of the wall material with that allowed by the standards.

Wall panels are reinforced with meshes and frames, they have embedded parts. Therefore, they are examined as reinforced concrete structures with the determination of the protective layer of concrete, the location and diameter of the reinforcement, etc. They use ISM and IZS devices. The condition of the reinforcement and embedded parts is revealed by opening at least in three places.
Carefully examine the piers and lintel sections of the walls. The most dangerous are horizontal cracks in the walls and vertical cracks in the lintels. Cracks can occur from various factors: from temperature changes, foundation settlements, concrete shrinkage, overvoltage, etc.
It is necessary to determine whether these are old cracks (passive) that can be repaired immediately, or if they are active developing cracks. To do this, install beacons on the wall, cleared of cladding or plaster. Two beacons are installed on each crack - in the zone of greatest opening and at the end.
When examining wooden walls or sheathing, it is imperative to determine the moisture content of wood and backfills; determine the degree of infection with rot, fungi, bugs, etc. Samples of 10x5x1 cm are taken from moistened places and sent for microbiological analysis.

Defects and damage to building walls

According to the type of construction material used, the walls are divided into stone (walls made of bricks, small and large blocks and panels) and wooden.
The main defects of stone walls are:

cracks;
layering of rows of masonry;
masonry weathering;
deviation of the walls from the vertical;
bulging and subsidence of individual sections of the walls;
destruction of the outer surface layer of wall material and architectural details;
loss of individual bricks;
absence and weathering of the masonry seam solution;
peeling and destruction of the protruding parts of the walls;
punched and unsealed holes, niches, furrows;
dampness and freezing of structures;
efflorescence from mortar and wall material.

Defects in large-panel buildings, as a rule, appear in panels of external walls, in internal load-bearing walls with smoke ventilation ducts, in vertical and horizontal joints between panels, in window and door frames adjoining walls, in external corners of buildings, in places where floors and roofs meet walls, as well as in joints of the frame and its interfaces with the enclosing structures. Usually this:

displacements and distortions of panels in and out of the plane of the walls;
leaks and high air permeability of joints;
insufficient thickness or low thermal properties of panel materials, leading to freezing of panels in winter;
corrosion of embedded and overhead fasteners in joints and panel reinforcement with separation of protective layers on wall surfaces;
destruction of the outer moistened layers of panels due to alternate freezing and thawing;
cracks in the panels from force, temperature and humidity effects.

In large-block buildings, the following defects and damage to the walls are observed:

leakage and high air permeability of the joints;
destruction of sealing joints;
corrosion of steel embedded parts;
exposure or insufficient protection of reinforcement in the outer reinforced concrete layers of wall panels;
destruction of the texture layer;
the appearance of rust spots on the walls.

The most common defects in wooden walls are:

rotting of wood and damage to it by grinder beetles and house mushrooms;
freezing;
high air permeability of the grooves of the cobbled walls and joints in the shield panels;
bulging walls, subsidence of corners;
destruction or damage to plaster, cladding and finishing of corners and junctions of internal walls with external ones;
sediment backfill in frame walls;
damage, low slope and loose fit to the walls of the drain boards;
loss of waterproof properties of rolled waterproofing on the base.

Causes of decay lower parts wooden walls can be:

absence or incorrect arrangement of drain boards;
lack of a waterproofing gasket between the base and the crowns or strapping;
lining the walls with bricks without underground waterproofing.

Freezing and blowing of wooden walls is due to:

incorrect fitting of logs along the length or at intersections;
poor caulking of seams;
lack of corner pilasters.

In frame and panel buildings, this can occur due to the precipitation of the insulation, poor heat and air insulation of the joints, as well as insufficient density of the skins.

For walls using asbestos-cement sheets, the following defects are characteristic:

cracks and punctures due to mechanical influences;
swelling or warping as a result of wetting and drying;
separation of sheets and spalling of the cement slurry due to alternate freezing and thawing in a wet state;
damage to fasteners and loss of sheets.

The following defects may occur in walls using metal:

delamination of facings from the side of the premises in the areas of seams, panel frame elements and other heat-conducting inclusions;
destruction of anti-corrosion protective coatings and corrosion of metal in areas subject to systematic wetting or exposure to chemically aggressive environments, as well as in places of contact of dissimilar metals;
mechanical damage to the facings (curvature, holes, etc.);
defects and damage to the joints of sheets or their fastenings to the frame of the panels or to the supporting structures.

Wall dampening

The most common cause of accelerated wear of the walls is their periodic wetting in combination with temperature alternating fluctuations. Moisture penetration into the wall material can occur as a result of:

sorption absorption of moisture by the material in the open air;
capillary absorption or diffusion of the material when it comes into contact with a liquid;
penetration of steam into the material from the ambient air;
physical and chemical processes.

If wet areas, mold, moss, efflorescence, etc. are found on the walls. their causes should be identified. This is usually due to such factors:

lack of or damage to waterproofing;
damage to technological or plumbing devices;
waterlogging of the walls from wet production processes inside the building;
violation of the temperature and humidity conditions in the premises;
storage near the walls of industrial raw materials, production waste, parts with large surfaces that impede the free circulation of air, which contributes to the spread of dampness on the surface of the walls.

Freezing walls

One of the defects of the outer walls of buildings is freezing. A sign of freezing is the presence of spots of dampness, condensation and mold, protruding on the inner surfaces of the walls when the outside temperature drops. During severe frosts, frost can appear on the walls and ice formation. These defects are especially intense at the vertical and horizontal joints of the panels of the upper floors. The destruction of the masonry of the walls, the plinth and the eaves of the roof is facilitated by a malfunction of the drainpipes, as well as the use of bricks with low frost resistance. On the facades of buildings lined with ceramic tiles, there is bulging of the cladding, the exit of individual slabs from the plane of the walls, cracks and spalls in the corners of the tiles, disorder of fasteners, rusty smudges from the seams of the cladding. During the operation of balconies, loggias and canopies, the following damage may occur:

destruction of cantilever beams and slabs;
chipping of supporting platforms;
peeling and destruction of the protective layer;
slope to the building of the floor of balconies and loggias, as well as covering the canopies;
absence and improper implementation of the waterproofing layer;
cracks in the plates;
weakening or damage to the fasteners of the fences.

Weathered walls

The destruction of masonry walls by weathering occurs in buildings, the nature of the production processes in which is associated with high humidity indoor air and in walls made of insufficiently frost-resistant materials (for example, silicate brick). The destruction of external plaster and masonry walls in buildings with high humidity indoors occurs as a result of the accumulation of moisture under the plaster layer (moisture condensation), and in winter - its icing, which is accompanied by the destruction of plaster and masonry. During the operation of large residential buildings, there are often leaks in their walls through vertical and horizontal joints of external walls, joints of interfaces of window and door frames, slabs of balconies and loggias, coating panels and panels of external walls, which is associated with poor sealing of joints, the absence of rain barriers in horizontal joints, decompression channels and drainage devices in vertical joints. The structure of the walls can also become damp due to condensation of moisture on their inner surface or in their thickness. Humidification of the walls, along with the deterioration of their strength properties, leads to a deterioration in their thermal properties. Therefore, in order to ensure the normal life of the building and its operational qualities it is necessary to prevent the penetration of moisture into the walls.

wall cracks

Cracks in the walls appear due to:

uneven settlement or subsidence of foundation foundations;
temperature stresses with a large length of the walls (lack of expansion joints);
insufficient bearing capacity of walls (in narrow piers, lintels, under beam supports, etc.).

So, in stone walls, the factors contributing to the formation of cracks are:

poor quality of masonry (non-compliance with dressing, thick mortar joints, backfilling with brick fight);
insufficient strength of the brick and mortar (fracturing of the brick, high mobility of the mortar, etc.);
joint use in masonry of heterogeneous strength and deformability of stone materials (clay and silicate bricks, clay bricks and cinder blocks);
the use of stone materials for other purposes (for example, silicate brick in bathrooms - in conditions of high humidity);
poor quality of work in winter (use of icy bricks, use of frozen mortar);
the absence of temperature-shrinkage seams or an unacceptably large distance between them;
aggressive impact external environment(acid, alkali and saline), alternate freezing and thawing, humidification and drying;
uneven settlement of foundations in the building.

Wall Crack Analysis

Important information about the condition of the walls is provided by the analysis of cracks in the walls. By surface cracks in brick walls, one can judge the degree of wear and strength of the wall material and the wall itself as a whole. If the walls are in good condition (wear up to 20%), the masonry is monolithic, has no visible changes, the stones and the mortar retain their strength, the adhesion of the stones to the mortar is not broken. In a satisfactory condition (wear from 20 to 40%), in some places there is a separation of the masonry into separate stones due to the incipient loss of adhesion to the mortar, however, the mortar still retains its strength. If the masonry is in poor condition (wear 40...60%), its progressive weakening is observed; loss of mortar strength; the appearance of hairline cracks, loss or destruction of stones; bulging of individual places of the wall. Overloading of wall sections in a satisfactory condition of the masonry is manifested in the appearance of cracks in vertical and horizontal seams. If the masonry is in poor condition, cracks from overload go through the stones. The decrease in the bearing capacity is especially pronounced in the presence of horizontal cracks in the walls and vertical cracks in the bulkhead structures. Cracks appear not only from the insufficient bearing capacity of the walls, but also due to the poor condition of other structures: bases, foundations, etc. Control over the behavior of cracks is carried out with the help of beacons, strain gauges, etc.

Partitions of civil buildings must have the necessary soundproofing properties, fire resistance, moisture resistance. Faults identified during operation must be promptly eliminated. The following damages and defects are found in partitions: unsteadiness, bulging, cracks and crevices at the points of their interface with walls and ceilings, leaks around pipelines, falling out and peeling of facing plates, cracking and destruction of plaster, moistening at the locations of water supply and heating devices, increased sound conductivity . Wooden partitions rot, are damaged by house fungus, insects.

When examining partitions, one should determine their design, nature of work, stability, strength, sound insulation, causes of deformations. The design of the partition is revealed by external examination and opening in separate places. Detected bulges and buckling are measured without fail. The stability of the partitions is determined by calculation, taking into account the existing loads, depending on the nature of the work and size.
Sound insulation of inter-apartment partitions is controlled in accordance with GOST 27296-87.

In case of bulging or significant inclination with the appearance of cracks, the causes should be identified, the structure should be strengthened, and, if necessary, the partition should be sorted out or replaced. Buckling of wooden partitions can occur due to the leaning of ceilings on them or unreliable fastening to the ceiling and walls.

Cracks in the passage of pipelines occur due to temperature changes and the deformations caused by them. The space between the sleeve and the central heating pipe is caulked with an asbestos cord, and the surface is rubbed with a cement-lime mortar with the addition of 10-15% asbestos dust.

Cracks in the plaster of wooden partitions occur due to the settlement of walls, shrinkage of wood and vibration of floors. Exfoliated plaster must be beaten off, the surface cleaned and re-plastered with the same solution. Lagging ceramic tiles must be removed and redone.

Damp spots and damage to the lining and plaster of plank or frame-backfill partitions indicate rotting wood. It is recommended to beat off the facing layer, replace rotten elements, dry and restore the finishing coating.

Damaged areas of dry plaster sheathing should be replaced. Small holes can be sealed with plaster mortar. When cracks appear, peeling of cardboard at the joints of sheets, these places are cleaned, pasted over with sickle and putty.

Insufficient sound insulation occurs due to the small mass of partitions, the appearance of cracks and crevices, compaction and sedimentation of the backfill, non-compliance with the required thickness and clogging of the air gap.

The cavities formed in the frame partitions must be laid with mineral wool slabs or backfilled. If the sound conductivity of the partition remains elevated after sealing cracks, crevices and gaps, it is necessary to carry out additional sound insulation.

Partitions made of wooden elements, gypsum or gypsum-alabaster slabs and panels require careful protection from getting wet. When such partitions are located in damp rooms, they must be lined with waterproof tiles or covered with oil paint.

During operation, dismantling, rearranging or installing new partitions, punching openings is allowed only with special permission.

It is forbidden to fix wall-mounted equipment on asbestos-cement partitions of sanitary cabins without special devices.

Technical operation of partitions.

Partitions of civil buildings must have the necessary soundproofing properties, fire resistance, moisture resistance. Damage and Defects:

unsteadiness, buckling, cracks and crevices in the places of their interface with walls and ceilings

leaks around pipelines

Falling out and peeling of facing plates

Cracking and destruction of plaster, moisture at the location of water supply and heating devices

increased sound conductivity.

Wooden partitions rot, are damaged by house fungus, insects.

Sound insulation of inter-apartment partitions is controlled in accordance with GOST 27296-87.

Cracks in the passage of pipelines occur due to temperature changes and the deformations caused by them.

Damp stains and damage to the lining and plaster of plank or frame-backfill partitions indicate rotting wood. It is recommended to beat off the facing layer, replace rotten elements, dry and restore the finishing coating.

Technical operation of the roof structure

Pitched (attic) roofs must be operated in good condition of the roof, load-bearing roof structures and normal temperature and humidity conditions in the attic.

Inspection of the roof is carried out 2 times a year - in spring and autumn, and roll - at least 1 time in 2 months.

Pitched roofs made of sheet and piece materials are checked both from the outside and from the side of the attic, while revealing the presence of wet spots on the insulation of the attic floor.

Technical operation of steel roofs:

On steel roofs check:

The state of the paint or protective layer, ridges, folds, grooves, overhangs and attaching them to crutches;

Condition of wall gutters, trays and funnels of downpipes;

The presence of corrosion, holes and dirt, especially near the sewer folds.

Measures for the technical operation of steel roofs:

Sealing of defective recumbent and standing folds with their preliminary lubrication with red lead;

Installing patches of burlap or fiberglass on minium putty (2 wt. H. Drying oil, 1 wt. H. Grated minium, 2 wt. H. Grated white and 4 wt. H. Chalk) and sealant on small holes (up to 5 mm) ;

Replacement of individual heavily damaged plates with new ones.

Metal roofs are painted with oil paint (for 2 times) at least 1 time in 3-4 years, from galvanized steel - when corrosion appears on them.

Technical operation of roofs made of piece materials:

In roofs made of tiles and asbestos-cement sheets, check:

Damage and displacement of individual elements;

Leaps on each other;

The correctness of the overlap, especially in the ridge and rib rows;

Weakening of the fastening of the roof to the crate.

Measures for the technical operation of roofs made of piece materials:

Damaged tiles and asbestos sheets should be replaced. In tiled roofs, the seams are smeared from the side of the attic with a special solution.

If the lower sheets of asbestos cement are not tightly overlapped with sheets of the upper row, it is necessary to lay a layer of roofing felt or roofing material between the sheets and the crate, this will prevent snow from blowing into the attic.

Technical operation of roll roofs

Rolled roofs must be cleared of debris before inspection.

During the inspection of rolled roofs, it is necessary:

Check the joints of the panels and their sticking to the underlying layers or base,

Check the condition of the junction of the roof to the walls, pipes;

Check for local subsidence, ruptures and holes, cracking of the cover and protective layers.

Measures for the technical operation of roll roofs:

Restoration of the surface coating and protective layer, which must be renewed at least after three years, since the coating dries out over time, and the dressing is weathered. Painting is carried out for 2 times with bituminous varnish with the addition of 15% (by weight) of aluminum powder. Before this, the roof surface is cleaned and pre-primed with the same varnish. The protective layer on the surface of the rolled roof increases its resistance to the damaging effects of solar radiation and possible mechanical damage. Overheating of the "black" surface of the roof on a summer day worsens the temperature and humidity conditions of the interior, makes the roofing carpet unusable in a few weeks if the protective layer is damaged. The protective coating is restored on roofs with a slope of less than 10% by applying bituminous mastic, followed by coarse sand or light gravel with a layer of 8-15 mm.

Correction of unsatisfactory mates of the roof with walls and other devices protruding above the roofs. Roof coverings are led into the otters of building structures, on sleeves or branch pipes of pipelines and protected with aprons made of galvanized steel. When the parapet blocks get wet, they are covered with roofing steel or a waterproof film.

Replacing damaged areas of roll roofing with appropriate material, gluing it with mastic.

Lesson #17

Topic: METHODOLOGY FOR ASSESSING THE TECHNICAL CONDITION OF WALLS

Walls are vertical load-bearing and enclosing structures. They are subjected to various force and non-force influences; perceive loads from their own mass, from ceilings, coatings, roofs, wind, seismic loads, solar radiation, etc.

External walls consist of the following elements: piers, plinth, openings, cornices, parapets. The inner wall includes only elements of the openings. The walls must meet the requirements of strength, durability, fire resistance, provide the premises of the building with the appropriate temperature and humidity conditions, protect the building from adverse external influences, and have decorative qualities.

The task of the technical operation of the walls of buildings is to maintain their bearing capacity and enclosing properties throughout the entire service life; The most frequent and characteristic damage to the stone walls of buildings and structures are:

- wall deformations (deflections, bulges, deviations from the vertical);

- spalls, shells, potholes and other discontinuities;

- moistening masonry walls, weathering and leaching of mortar from masonry joints;

– damage to protective and individual layers;

- destruction of the main material of the walls.

In large-panel buildings, special attention is required: panels of external walls; internal load-bearing walls with ventilation panels, vertical and horizontal joints between panels of external walls; seams between panels and window frames; external units of the building; places of conjugation of attic floors with walls; frame joints, etc.

The main causes of damage to the walls of buildings during operation are:

- uneven settlement of various parts of buildings;

- low quality of the material from which the walls are made;

– errors in the design (unsuccessful constructive solution interface nodes, incorrect accounting of existing loads, loss of stability due to an insufficient number of connections, etc.);

- low quality of work;

– unsatisfactory operating conditions;

- lack or violation of waterproofing of walls, etc.

According to the material, the following main types of wall structures are distinguished: wooden, stone, concrete and walls made of non-concrete materials.

Brick walls during operation must be systematically inspected in order to detect cracks in the body of the wall, delamination of masonry rows, sagging and falling out of bricks from lintels above openings, destruction of cornices and parapets.

The appearance of cracks in the walls of buildings can be caused by the following reasons: uneven settlement of walls, washing out of soil from under the base of the foundation by groundwater; due to pipeline accidents, wetting and settlement of soils under the foundation due to damage or lack of a blind area, as well as local settlement of walls caused by the proximity of objects under construction, etc.

There are different types of cracks. Hairline cracks are not noticeable on the surface of the plaster, there is no fracture of the brick under them. Such cracks appear due to shrinkage of plaster or small sediments and distortions of walls and foundations; they can be observed in the joints of masonry, on bricks. They do not pose a danger to the building. When cracks are found, it is necessary to establish control over the structures.

Opened cracks indicate significant displacements occurring in parts of the building.

Vertical cracks of the same width in height appear due to a sharp settlement of parts of the building, inclined cracks - with a constant increase in the settlement of the foundation and wall away from the place of crack formation.

Vertical cracks, diverging upward, are formed when the settlement of one or both parts of the wall gradually increases. Inclined cracks approaching upward testify to the settlement of the section of the wall between the cracks.

Horizontal cracks appear as a result of a sharp local settlement of foundations. In this case, it is necessary to take measures to strengthen the base. In long walls, temperature cracks can occur, the opening size of which, depending on the outside temperature, can change (increase or decrease) (Fig. 3.2).

Rice. 3.2. The reasons for the formation of cracks in the bearing walls due to the unsatisfactory condition of the bases and foundations:

a - weak soils under the middle part of buildings;

b- the same at the end of the building;

c - extensive excavation c close proximity from the building;

d- the absence of a sedimentary seam between parts of buildings of different heights;

d-proximity of a new high-rise building near a low-rise one.

When cracks appear, it is necessary to install beacons to determine the nature of crack behavior. If the formation of cracks has stopped, they are sealed with a continuous solution. If the width of the cracks increases, then it is necessary to examine them in detail and eliminate the causes that led to the formation of cracks.

If the walls are blown through the filling of openings, it is necessary to beat off the plaster at the slopes of the openings and carefully caulk the gaps between the window and door frames and the masonry of the walls, and restore the plaster.

When bricks fall out on the weathered sections of the walls, the sections should be cleared and then repaired with the material from which the wall is made.

To protect the outer corners of the basement (at through passages through buildings) from damage, it is necessary to install restrictive bollards or protect the corners by sealing them with steel corners to a height of 2 m. When using stone walls, it is prohibited to punch window and door openings in the brick walls of the building without special permission, fasten guy wires to them for hanging wires.

It is forbidden to store various materials, firewood, etc. in the immediate vicinity of the walls.

To reduce the humidity of the premises, the operation of ventilation devices is checked and, if necessary, adjustment and adjustment work is carried out. Strengthening the operation of the ventilation system with a natural impulse contributes to an increase in the temperature of the indoor air, for which the area of heaters in a room with insufficient ventilation is increased. Moistened structures are dried with heating devices.

In rooms with high humidity, it is necessary to arrange a vapor barrier on the surface of the outer walls from the side of the rooms, followed by plastering, painting with oil paint or tiling.

Wooden walls are made of chopped, panel, paving, frame.

Wooden walls are subject to the damaging effects of fungi and woodworms, and therefore constant monitoring and careful inspections are necessary.

It is necessary to monitor the possible appearance of bulges in the walls. The exit of the wall structure from the vertical plane indicates the insufficient strength of their bonds, which must be strengthened.

The temperature and humidity regime is important for the durability of structures made of wood, since its violation leads to moisture and decay, overheating and weakening of the wood.

During the operation of wall structures made of wood, it is necessary to pay attention Special attention to places most dangerous in terms of decay, i.e. on enclosing structures facing north, as well as on walls located in rooms adjacent to sources of moisture release (bathrooms, kitchens, etc.).

Leaks (crevices, cracks) must be sealed on the outer surfaces of the walls in order to prevent the penetration of atmospheric moisture into the structure, as well as drain boards of socles, windows, belts with a slope of at least 1:3 should be tightly fitted to the walls.

It is necessary to restore or re-perform the rolled vapor barrier of the frame walls in case they are wetted. The vapor barrier layer is placed directly under the inner lining; from the side of the room, the walls must be plastered.

In wooden plinths, rotten parts of the pick-up are replaced, and the backfill of the plinth is replenished. In order to avoid wetting the backfill under it, along the perimeter of the base, stuffing is done with a layer of clay 30 mm thick.

The crowns of the strapping and the rack, severely damaged by wood destroyers, are replaced by antiseptic treatment of the preserved and new parts with a waterproofing device along the top of the foundation or basement.

When condensation moisture appears in the form of wet spots on the walls or ceiling, it is necessary, after eliminating local defects, to increase the thermal insulation from the cold surface of the fences, to increase the heat transfer of the heating system, for example, by installing additional heating devices, to increase the ventilation of the premises, etc.

The structures of wooden walls are combustible, therefore, it is necessary to strictly observe the general rules of fire safety - for this, such structures should be protected by covering them with flame retardants and impregnating them with flame retardant solutions.

To protect against moisture and bio-pests, wooden wall structures are treated with pentaphthalic, perchlorovinyl and other enamels, transparent varnishes PF-115, PF-170, XV-110, XV-124, XV-785, UR-293, etc.

OFP-9 fire-retardant phosphate coating, VP-9 intumescent coating, AK-151KR03 fire-retardant acrylic paint are used as protective compositions, water-soluble ammonate salts, boric acid, phosphate acid salts, etc. are used as flame retardants.

When operating large-panel walls, it is necessary to pay special attention to the state of sealing and strengthening the expansion joints of horizontal and vertical joints, the presence and nature of cracks in the body of the panels and the textured layer.

Approximately 30-35% leaks; freezing, delamination of the interior decoration of the premises is due to unreliable sealing of the joints of the wall structural elements. The reasons for this are the imperfection of design solutions, poor quality work on sealing joints, etc.

To ensure the tightness of the joints, it is necessary to carry out scheduled preventive measures to seal the joints and repair wall panels in a timely manner that prevents the loss of their operational properties.

When operating large-panel buildings, it is necessary to carefully inspect the walls for cracks at the junction of the outer and inner walls; floors and balconies with walls; flights of stairs and landings between themselves and with the walls of staircases; pay attention to the appearance of damp spots and traces of freezing on the walls or in the corners, rusty spots on the walls and at the locations of embedded metal parts.

To prevent the appearance of rust spots, the protective layer should be 20 + 5 mm, reliable fixation of the flexible reinforcement should be 3-4 mm.

Detected cracks on the surface of the walls, peeling of the textured layer or tiles are controlled by beacons. Cracks are sealed with a mortar and material that is homogeneous with the wall material, if they do not increase. In case of further crack opening, it is necessary to carry out a more thorough examination, since a significant crack opening (over 0.3 mm) can lead to a decrease in the bearing capacity of the walls and further destruction of concrete, corrosion of reinforcement and embedded parts. If cracks are found at the junctions of the partitions with the walls, they should be expanded, cleaned and caulked with tow, mineral felt or sealed with polyurethane foam.

If the dampness on the inner surface of the corners of the outer walls is stable, then the inner surface of such corners is insulated.

Freezing of multilayer panels due to poor quality of their prefabrication or wetting of the insulation layer is eliminated by opening the heat-insulating layer in places of freezing to a reinforced concrete slab, followed by sealing it with dry heat-insulating material and restoring the protective layer.

If a reinforced concrete slab is mechanically damaged in a multilayer wall panel with a damaged reinforcing mesh, it is necessary to weld the ends of the damaged reinforcement, concrete flush with the outer surface of the slab and restore the finishing layer.

To prevent freezing of walls, the appearance of moldy spots, mucus, condensate on the internal surfaces of external enclosing structures, the moisture content of materials should be: expanded clay - 3%, slag - 4-6%, foam concrete - 10%, aerated concrete -10%; humidity of walls: wooden - 12%, brick - 4%, reinforced concrete (panel) - 6%, expanded clay concrete - 10%, insulation in the walls - 6%.

In the first two years of operation, prefabricated buildings with increased humidity of wall fences must be intensively heated and ventilated.

Panel joints must meet the requirements of: water protection through the use of sealing mastics in compliance with the technology of their application and high-quality surface preparation; air protection due to sealing gaskets made of poroizol, gernite, vilaterm, tow and other materials with mandatory compression of at least 30-50%, as well as thermal protection by installing heat-insulating packages. Regulated opening of joints against temperature deformations: vertical - 2-3 mm, horizontal - 0.6-0.7 mm. In closed type joints, waterproofing is achieved by sealant, air-sealing materials with mandatory compression of 30-50%; thermal insulation - with thermal packs or a "wool" device with a width of at least 300 mm. Butt joints with leaks must be sealed from the outside with effective sealing materials (elastic gaskets and mastics).

Maintenance of the walls should be carried out during the entire period of operation. The minimum duration of effective operation of the walls:

- large-panel buildings with an insulating layer of mineral wool boards - 50 years;

- large-panel single-layer lightweight concrete - 50 years;

- especially capital, stone (brick with a thickness of 2.5-3.5 bricks) or large-block on a complex or cement mortar - 40 years;

- ordinary stone (brick with a thickness of 2-2.5 bricks) - 30 years;

- stone lightweight masonry made of bricks, cinder blocks and shell rock - 15 years;

- wooden chopped and block-shaped - 8 years. Minimum service life for sealed joints:

– exterior wall panels with non-hardening mastics – 80 years;

- the same, curing - 80 years;

– junctions of window and door blocks to the edges of openings 60 years.

The list of main works on the current repair of walls:

- sealing cracks, jointing, restoration of cladding and re-laying of individual sections of brick walls with an area of up to 2 m 2;

- sealing joints of elements of prefabricated buildings and sealing potholes and cracks on the surface of blocks and panels;

- punching holes, nests, furrows;

- change of individual sections of the sheathing of wooden walls, crowns, frame elements, strengthening, insulation, caulking of grooves;

– restoration of piers, lintels, cornices, placing fallen stones on mortar;

- reinforcement of freezing sections of walls in separate rooms;

– elimination of dampness, blowing;

– cleaning and repair of ventilation ducts and exhaust devices.

Lesson #19

Topic: METHODOLOGY FOR ASSESSING THE STATE OF FLOOR STRUCTURES

Overlappings perform load-bearing and enclosing functions,play the role of horizontal stiffening diaphragms, providewhich contribute to the stability of the building as a whole. They perceive the load from people, engineering equipment, furniture and transfer it to the load-bearing walls. Overlappings must have the necessary strength, heat-shielding, sound-proofing, waterproofing and other properties.

According to the location in the building and the operational purpose, the floors are divided into above-basement, basement, interfloor, attic.

The factors that determine the material and design of the floor are the force and non-force effects acting on it.

Force impacts cause stress and deformation of the element, which manifests itself in deflections. Non-force impacts make it necessary to give the ceilings acoustic, thermal and other qualities that meet the requirements of operation.

The structural scheme of the floors is determined by the way the forces perceived by them are transmitted to the walls. Depending on this overlap are divided into beam and withoutbeam(slab).

In beam-type ceilings, the main load-bearing functions are performed by beams.

In slab-type ceilings, the supporting structure is a slab.

According to the material of the floor, they are classified into wooden, reinforced concrete, steel.

In wooden floors, it is important to correctly seal the ends of the beams into stone walls and protect them from decay. Wooden floors must be separated from masonry or massive metal parts of structures with waterproofing from two layers of roofing, glassine, roofing material and other materials.

The ends of the wooden floor beams are laid on the stone walls at the appropriate mark, embedded in the wall to a depth of 150-200 mm, while leaving the end free. The supporting part is wrapped with two layers of roofing material. Continuing the laying, they leave a niche to a depth of 200 mm, a width of 30-40 mm more than the width of the beam; minted with oiled tow; fix the side surfaces with masonry mortar to a depth of 30-40 mm from the inner edge of the wall, leaving the top of the beam free from rigid embedding. Through the tow on the top of the beam and the gap between the plinth of the clean floor, excess moisture evaporates from the beveled ends.

In the most difficult operating conditions, in the absence of a basement, there are plinth wooden floors.

The ceiling consists of load-bearing beams, vapor barrier, clean floor, sparse "black" floor, insulation. To ensure ventilation of the insulation structure in the basement, “vents” are arranged that are closed for the winter.

Rotting of wooden rolling and beams of wooden floors in the attic can occur due to leakage of the roof, insufficient insulation layer, unsatisfactory temperature and humidity conditions, poor ventilation of the attic. To ensure sound insulation of interfloor floors, it is necessary to install sound-proof gaskets under the logs or the floor base, in places where the floor mates with adjacent structures. Insufficient sound insulation may occur due to the low absolute density of the overlap and at the points of their intersection with pipelines.

To ensure the normal operation of the building, the deflections of the beams of interfloor wooden floors should not exceed 1/250, the beams of attic floors - 1/200.

In case of detection of sagging ceilings or strong swell of floors, it is necessary to open them and revise the structures of the floor: the state of rolling and lubrication; sufficiency of the backfill layer, especially in the basement and attic floors; the condition of the filing and the reliability of its attachment to the beams in a lightweight ceiling. Inspection of wooden attic floors with the removal of backfill and grease in the areas closest to the outer walls with a width of up to 1 m and with a thorough inspection and check of the condition of the wooden parts of the floor should be carried out at least 1 time in 5 years.

The disadvantages that occur in reinforced concrete floors during operation include: deflections, freezing at the outer walls, peeling of plaster, cracks at the junction of floors with walls.

The maximum allowable deflections of prefabricated reinforced concrete floors are determined in accordance with Table. 3.2.

Table 3.2

VERTICAL LIMIT DEFLECTIONS OF STRUCTURAL ELEMENTS

Structural element	Requirements	Vertical limit deflections f and	Loads for defining vertical deflections
Coverings and ceilings open for review, during the span, l, m: l = 24(12) l = 36(24)	Aesthetic and psychological	/120	Permanent and temporary
Coatings and ceilings in the presence of elements subject to cracking (screeds, floors, partitions)	constructive	/150	Effective after the completion of partitions, floors, screeds
Coverings and ceilings in the presence of hoists (hoists), overhead cranes, controlled: from the floor	Technological	/300 or a /150 (lower of the two)	Temporary, taking into account the load from one crane or hoist (hoist) on one track
from the cockpit	Physiological	/400 or a/200 (the smaller of the two)	From one crane or hoist (hoist) on one track
Ceilings subjected to the action of transported goods, materials, assemblies, equipment elements and other moving loads (including in case of trackless floor transport)	Physiological and technological	/350	0.7 full standard values of live loads or loads from one loader (the more unfavorable of the two)

Note:I- calculated span of a structural element; a - step of beams or trusses to which overhead crane tracks are attached; figures in parentheses were taken at a room height of up to 6 m inclusive.

If the deflections of the ceiling structure exceed the maximum allowable limits, then such a structure does not meet the requirements of normal operation and its reinforcement or replacement is necessary.

If there are cracks in the floor slabs, the cause of their occurrence should be determined, the condition of the concrete and reinforcement of the slabs should be assessed. If cracks with an opening width of more than 1 mm are found in the ceilings, it is necessary to open the protective layer, determine the condition of the reinforcement and concrete, and, based on the results, carry out the necessary restoration work.

When inspecting floors, pay attention to: on theloads, sagging and fluctuation of floors, cracks per monthmax adjoining to adjacent structures and in plaster orgrouting of ceilings, dampness of ceilings, insufficiency of soundisolation.

If wetting or oiling of interfloor ceilings is detected due to violations of the normal operation of pipelines, it is necessary to identify and eliminate their causes, remove the collapsed layer of concrete or plaster and apply a new one.

In case of supercooling of the wall section in the places where the reinforced concrete floorings of the interfloor ceilings rest on it, as evidenced by the presence of damp spots or frost, it is recommended to arrange a cornice near the ceilings of the attic and interfloor ceilings or to open the floor and insulate the ends of the flooring.

If sagging plaster or deep cracks are found in it, it is necessary to check the condition of the plaster by tapping. When bulging and peeling from reinforced concrete slabs, the plaster should be beaten off and replaced with a new one, made from a complex solution, with a preliminary notch on the surface of the slabs.

The increased humidity of the plates in the rooms above the showers may indicate a violation of the tightness of the ceiling, so they must be opened and the tightness restored.

During operation, the value of the maximum load on the floor, established by the project, must not be exceeded. Work on the laying or repair of engineering communications associated with a violation of the integrity of the load-bearing structures of floors must be agreed with the design organization.

Strengthening of floors, elimination of deflections, displacement of load-bearing structures of walls or girders in brick vaults, cracks and other deformations that reduce the bearing capacity of floors, must be carried out according to the project. supercooledceilings must be insulated as follows:

- attic floors: bring the thermal insulation layer to the calculated one; in the attic along the outer walls on a strip 0.7-1 m wide there should be an additional layer of insulation or a bevel of heat-insulating material at an angle of 45 degrees;

- interfloor ceilings: to strengthen the thermal insulation at the points of their junction with the outer walls, thermal insulation at the ends of panels and girders; plaster internal surfaces brick walls; seal the butt joints of panel walls and make bevels of insulating material 25-30 mm wide;

- ceilings over driveways and undergrounds: insulate in the areas where the entrance doors to the entrance and ventilation ducts of the basement walls are located, increase the thickness of the thermal insulation by 15-20% according to the project.

Attic floors with a bulk heat-insulating layer should have wooden walking bridges, and a lime-sand screed over the warming layer.

The minimum period of effective operation of building floors varies from 20 to 30 years

METHODOLOGY FOR ASSESSING THE STATE OF STRUCTURESPOLOV

Floors in buildings are arranged on the ground or on floors. The floors are subject to constructive, operational, sanitary and hygienic and artistic and aesthetic requirements. Floors should be well resistant to mechanical stress (abrasion, impact, punching), have the necessary rigidity and elasticity, have low heat absorption, be even, smooth, non-slip, not create noise when walking on them, be comfortable to use and have a good finish.

The following damages and defects occur in the floors: destruction of the paint layer of wooden floors; absence and clogging of ventilation grilles or slots behind the skirting boards; damage due to decay, abrasion, drying out and warping of boards and parquet staves, fluctuations and local subsidence; mobility and loss of individual rivets; the creaking of parquet floors laid on a wooden base; cracks and potholes, delamination from the base, uneven surfaces of ceramic and cement floors; delamination, shrinkage and fragility of synthetic floors, as well as high thermal conductivity (“cold” floors) of some floor structures, such as PVC tiles laid on a concrete base.

Faulty floors contribute to the appearance of damage to floors. Therefore, in apartments and places common use it is necessary to periodically check the technical condition of the floors, paying attention to the mode of their maintenance (washing, rubbing, protection from moisture), and promptly eliminate the detected malfunctions, preventing their further development.

The causes of defects in wooden floors are the use of sawn timber of high humidity, the laying of wide boards, improper operation (careless and abundant washing of plank floors with wetting the plank flooring, washing parquet floors instead of rubbing, lack of ventilation in the interfloor ceilings and floors of the first floor, untimely rubbing of the floor, etc.). d.).

In the floors of the first floor, with poor thermal insulation and insufficient ventilation of the underground, dampness and house mushrooms appear. Similar phenomena are observed in the absence of ventilation of the air gap in the floors on the logs of interfloor ceilings. Xylolithic floors can bulge where the substrate has been contaminated with lime mortar.

In linoleum floors, the integrity of the layer is broken due to frequent and heavy washing instead of rubbing or rubbing; with a wet cloth, due to damage, subsidence of the underlying layers, as well as shrinkage deformations of the material.

In the floors of synthetic tiles, the backlog occurs due to insufficient cleaning of the base from dust and dirt, with its high humidity, insufficient or dry layer of adhesive mastic. The edges and corners of the tiles may warp due to the fact that the tiles were laid before the mastic dries.

In ceramic tile floors, the reasons for the peeling of individual tiles are insufficient exposure after laying tiles on cement mortar, inhomogeneity of the mortar and its low strength, laying contaminated dusty tiles and mechanical impacts on the floor.

Potholes and premature local wear of concrete, cement, mosaic, asphalt, linoleum and other types of floors are the result of mechanical damage (when heavy objects are moved along them, hits, etc.).

Floors in buildings are made from materials that differ in composition and performance, and therefore require different methods of maintenance.

Plank floors for better protection from moisture and dirt, it is recommended to paint with oil paint or enamel at least 1 time in three years with their preliminary puttying.

Floors with increased fluctuations and deflections must be opened, the condition of the wood of the supporting structures and elastic pads must be checked, and then the structure must be repaired.

In case of strong drying, plank floors are united. Worn or damaged boards are replaced with new ones, the wood of which must be air-dry and antiseptic on three sides, except for the floor surface.

Upon completion of the repair, the floor is painted 2 times with a preliminary primer and putty of the planed surfaces.

The underground space of plank floors on logs on the ground with wooden floors should be ventilated through ventilation holes installed in the floor in two opposite corners of the room or in baseboards in the form of slots at the rate of 5 cm 2 per 1 m 2 of the area of \u200b\u200bthe room. The gratings above the holes must be laid on pads 10 mm above the floor surface.

Parquet floors periodically, at least 1 time in 2 months, rub with mastic or cover with wear-resistant varnish every 4-5 years with preliminary scraping of the surface. Before rubbing, the floors are wiped with a damp cloth. Washing parquet floors is not allowed.

If the parquet rivets are attached to the base with bituminous mastic, you cannot rub the floor with turpentine mastic, as it dissolves the bitumen and the floor turns black. For such floors, only water-based mastics are used. The presence of bituminous mastic can be established by the dark color of the seams.

Parquet floors along the logs should be well ventilated. Deflection and unsteadiness of the floor, as well as the presence of damaged rivets, indicate the possible development of fungal or bug pests. In this case, it is necessary to open the floor and check the condition of the wood.

During the repair, parquet dumplings that have peeled off from the base are fixed, and the damaged ones are replaced with new ones, which should be laid so that they are 0.5-1 mm higher than the level of the existing floor. After that, you should make a guard and scraping.

To eliminate the creak, the parquet floor is re-tiled, laying it on a layer of building cardboard or roofing, with a selection of the missing and replacement of damaged rivets.

To protect against waterlogging and abrasion, as well as to reduce electrical conductivity, xylolitic floors are rubbed monthly with wax or drying oil and parquet mastic, and in everyday cleaning with soft, slightly damp rags. Every 2-3 years, xylolite floors are recommended to be covered with heated drying oil. You can paint such floors with oil paint. Lime, complex mortars, gypsum binders should not be used to level the base, since these materials adversely affect magnesia binders, leading to the destruction of xylolite.

Floors made of synthetic materials - from linoleum, PVC tiles and relin - it is recommended to wipe daily with a wet cloth; wash periodically with warm (but not hot) soapy water, followed by rinsing with clean water. Soapy water drying on linoleum is not allowed. Use neutral synthetic detergents. Soda and other alkalis make linoleum brittle. When washing floors, do not use pumice, sand, hot water. Persistent dirty stains from PVC linoleum and boards are removed with a rag soaked in turpentine or gasoline. In this case, care must be taken that the solvent does not get into the seams.

Reducing the possible static electrification of floors made of PVC linoleum and tiles is recommended to be achieved by increasing the relative humidity of the air in the premises to 50-55%, rubbing the floors at least 1-2 times a month with special mastics or wax, and treating with antistatic preparations. Rigid pads are placed under the legs of heavy furniture.

When repairing a linoleum floor, worn places are replaced with new ones made of a similar material, selecting patches according to the color of the coating. Exfoliated synthetic slabs, as well as local swellings of linoleum, are eliminated immediately after the appearance of a defect by gluing it onto the mastic, having previously cleaned and leveled the base. For thin linoleum, the base should be made of semi-rigid solid wood fiber boards, cellular concrete and other materials with a low heat absorption coefficient. Blisters should be pierced with an awl and air released from there, then smooth and glue linoleum. When linoleum is swollen by more than 25% of the floor area, it is necessary to make a continuous re-laying.

Mastic seamless floors within a month after installation are allowed Wipe only with a damp cloth; after this period, wipe and rub in the same way as linoleum floors. Small potholes and cracks in the floors are sealed with mastic.

Floors made of ceramic tiles, mosaic and cement, with damaged areas, are subject to accelerated destruction, therefore, the destroyed areas in such floors must be repaired as soon as possible with layers of the same thickness and from the same materials as the previously laid floors. Ceramic tiles that have lagged behind the concrete base must be cleaned of mortar and soaked in water before use. The surface of the base under the floor must be strong, notched, cleaned of dust, and also moistened (when using glue for fixing tiles and under asphalt floors, the surface is not moistened). Newly tiled floor areas should be kept damp for 4 to 7 days.

Potholes are eliminated in concrete and cement floors. The repaired places of the floors are ironed with cement on the second day.

Ceramic, mosaic and cement floors should be washed with warm water at least once a week.

METHODOLOGY FOR ASSESSING THE STATE OF PARTITIONS

Sound insulation of inter-apartment partitions is controlled in accordance with GOST 27296-87.

The fluctuation of partitions occurs most often due to the disorder of fastenings to walls and ceilings. In such cases, it is necessary to restore the weakened or install additional fastening parts (brackets, ruffs). In wooden partitions, fluctuation is also a consequence of decay of their lower part and subsidence of the base. In case of bulging or significant inclination with the appearance of cracks, the causes should be identified, the structure should be strengthened, and, if necessary, the partition should be sorted out or replaced. The buckling of wooden partitions can occur due to the leaning of ceilings on them or unreliable fastening to the ceiling and walls.

During operation, dismantling, rearranging or installing new partitions, punching openings is allowed only with special permission.

It is forbidden to fix wall-mounted equipment on asbestos-cement partitions of sanitary cabins without special devices.

Lesson #21

Topic: METHODOLOGY FOR ASSESSING THE CONDITION OF ROOFS

Pitched (attic) roofs must be operated in good condition of the roof, load-bearing roof structures and normal temperature and humidity conditions in the attic.

Inspection of the roof is carried out 2 times a year - in spring and autumn, and roll - at least 1 time in 2 months. The technical condition of pitched roofs with roofs made of sheet and piece materials is checked both from the outside and from the side of the attic, while revealing the presence of wet spots on the insulation of the attic floor.

On steel roofs, it is required to check the condition of the paint or protective layer, ridges, folds, grooves, overhangs and their fastening to crutches, the condition of wall gutters, trays and funnels of downpipes, the presence of corrosion, holes and fistulas and dirt, especially near the sewer folds. Inspection, cleaning and repair should be carried out only in felted or rubber shoes.

In steel roofs, it is necessary to seal faulty recumbent and standing folds with their preliminary smearing with red lead, for small holes and fistulas (up to 5 mm) put patches of burlap or fiberglass on red lead putty (2 weight parts of drying oil, 1 weight part of grated red lead) , 2 parts by weight of whitewash and 4 parts by weight of chalk) and sealant; replace individual heavily damaged plates with new ones.

Metal roofs are painted with oil paint (for 2 times) at least once every 3-4 years, from galvanized steel - when corrosion appears on them. If during operation damages are found on the roof before the next general painting of the coating, these places are repaired and painted immediately.

In roofs made of tiles and asbestos-cement sheets, during inspection, damage and displacement of individual elements, overlapping each other, correct overlapping, especially in ridge and rib rows, weakening of the roof fastening to the crate should be checked.

Damaged tiles and asbestos sheets should be replaced. In tiled roofs, the seams are smeared from the side of the attic with a complex solution with the addition of tow. In case of loose overlapping of the lower sheets of asbestos cement with sheets of the upper row, it is necessary to lay a layer of roofing felt or roofing material between the sheets and the crate, which will prevent snow from blowing into the attic. Repair of roofing from asbestos-cement sheets should be carried out from mobile ladders.

Rolled roofs must be cleared of debris before inspection. Walking on them is allowed only in soft shoes. During the inspection, it is necessary to check the joints of the panels and their sticking to the underlying layers or base, the condition of the junction of the roof to the walls, pipes, the presence of local subsidence, breaks and holes, cracking of the cover and protective layers.

Care of rolled roofs consists in restoring the surface coating and protective layer, which must be renewed at least after three years, since the coating dries out over time and the dressing erodes.

Painting is carried out for 2 times with bituminous varnish with the addition of 15% (by weight) of aluminum powder. Before this, the roof surface is cleaned and pre-primed with the same varnish.

The protective layer on the surface of the rolled roof increases its resistance to the damaging effects of solar radiation and possible mechanical damage. Overheating of the "black" surface of the roof on a summer day worsens the temperature and humidity conditions of the interior, makes the roofing carpet unusable in a few weeks if it is damaged. protective layer. The protective coating is restored on roofs with a slope of less than 10% by applying bituminous mastic, followed by coarse sand or light gravel with a layer of 8 - 15 mm.

Unsatisfactory connections of the roof with walls and other devices protruding above the roofs are corrected. Roof coverings are led into the otters of building structures, on sleeves or branch pipes of pipelines and protected with aprons made of galvanized steel. When the parapet blocks get wet, they are covered with roofing steel or a waterproof film.

Damaged areas of the roll roofing are replaced with the appropriate material, gluing it with mastic.

Inspection of the supporting structures of the roof is carried out after the inspection of the roof.

In wooden structures, the following damages and defects are encountered: broken joints in the joints between rafters, poor waterproofing between stone and wooden structures, rotting and deflection of building legs, battens and other elements.

When examining the wooden elements of roof structures, the condition of the wood is carefully examined in order to detect mold, rot and damage by wood-destroying insects.

Especially carefully it is necessary to inspect roof structures during the first three years of operation. During this period, defects may appear due to shrinkage and shrinkage, or, on the contrary, increased humidity of both wood and stone structures. In the first year after the acceptance of the building into operation, the tightening of bolts, roofing felts and clamps to eliminate gaps and cracks in the nodes is carried out every 3 months.

Rotting of wooden structures occurs due to moisture in the absence or insufficient insulation from masonry, unsatisfactory temperature and humidity conditions in the attic, and leaks in the roofing.

It is allowed to evaluate the strength qualities of wood in places of destruction by the number of annual layers in 1 cm, the percentage of late wood in accordance with GOST 16483.18-72 *, the absence of fungi that reduce strength, and colors. The moisture content of the wood is determined using an electronic moisture meter.

Defects in the supporting structures of the roof, associated with decay, insect infestation, are eliminated immediately. Regardless of the systems of damage and its causes, the entire wood of the structure is antiseptic. If the defeat is not dangerous, then only its cause is eliminated.

The rafter legs that have become unusable are reinforced, and the damaged parts of the Mauerlats and battens are replaced. With significant deflections of the rafter legs, additional racks, girders and struts should be installed. In this case, the racks should not be based on floors, but on load-bearing walls.

In reinforced concrete structures, the main damages are: the destruction of concrete on the surface of the elements, the absence of a protective layer, the exposure and corrosion of reinforcement, deflections, cracks and potholes.

Premature wear of reinforced concrete structures is facilitated by the low grade of concrete products and the insufficient thickness of the thick layer.

Inspection establishes the presence of cracks in tensioned and bent elements or reinforcement exposures, the condition of the protective coatings of embedded parts and welded joints is checked.

Cracks found in the supporting structures, noticeable deflections are measured and organized using devices for monitoring the condition of damaged elements. Deflections of structures, cracks in them are considered harmless if they do not increase after the start of observations, and their magnitude does not exceed the standard values. Potholes and cracks in this case are sealed with cement mortar.

If the damage has led to the loss of the bearing capacity of the structure, then they should be strengthened or replaced.

Lesson #23

Topic: METHODOLOGY FOR ASSESSING THE CONDITION OF STRUCTURES OF STAIRS

Stairs are designed to communicate between floors and evacuate people from the premises.

During the operation of stone and reinforced concrete stairs, the following defects may occur: corrosion of metal stringers, deflections of reinforced concrete marches, looseness of the marches to the walls, cracks in the landings and steps, potholes in the steps, weakening of the fastening of fences, handrails and safety nets, destruction of the finishing layer and ceramic floor tiles on landings, burrs on the railings. These shortcomings appear due to abrasion of steps when walking, dragging heavy objects without taking the necessary precautions, making steps and platforms from wear-resistant materials, fragile sealing of railings in nests or poor welding to the march. The steps of the first marches are subject to the greatest abrasion, since the stairs of the lower floors are used more people. Ladder faults should be corrected as soon as they occur.

During the operation of wooden stairs, rotting, abrasion or other damage to the supporting elements of the stairs, insufficient strength of fastening the bowstrings to the stringer beams and stair railings to the bowstrings, peeling and destruction of the paint layer are observed.

Monitoring the condition of the stairs consists in periodically checking the strength of their load-bearing elements, the junctions of the stairs with the walls, and the fastening of the railing. The technical condition of the stairs is evaluated based on the results of scheduled inspections and surveys that are carried out during the design of a major overhaul and to identify the causes of deformations.

Inspection of stairs is recommended to start from the entrance to the house. All flights of stairs and landings are subject to inspection from above and below. During the inspection, the following is established: the type of stairs according to the material and design features; the condition of the elements and their interfaces, places for embedding in walls, fixings of stair gratings; the presence of deformations, cracks and damage. To identify the causes of deformations and damage to the stairs, it is necessary to perform openings in the places where the supporting structures are embedded in the walls.

When examining stairs made of prefabricated reinforced concrete elements, the following are determined by their appearance: the state of embedding landings in the walls; the condition of the supports of flights of stairs and metal parts in the places of welding; the presence and spread of cracks and damage on landings.

When examining stone stairs along metal stringers, the following are established: the condition and strength of the embedment in the wall of the beams of landings; corrosion of steel bonds; the condition of the masonry in the places where the beams of the landings are embedded. Particular attention should be paid to the marches leading to the basement, in which one can often see deep corrosion of the stringers. In beskosour hanging stone stairs, the condition and strength of the sealing of the steps in the masonry walls are checked.

The minimum allowable support of the elements of stairs on concrete and metal surfaces is 50 mm, on brickwork - 120 mm, the violation of the horizontality of the landings should be no more than 10 mm, and the steps of the stairs - no more than 4 mm, the deviation of the railing from the vertical - up to 6 mm .

When inspecting wooden stairs using metal stringers and wooden bowstrings, the following is established: the condition and strength of the embedding of landing beams into the walls; reliability of fastening bowstrings to beams; the condition of the wood of the bowstring, steps, beams; the presence of moisture, damage by rot and pests.

Strength characteristics are determined using non-destructive methods. Probing is carried out to determine the type and boundaries of damage to wooden elements. The deflections of the bearing elements are set using deflection meters and a level. When deflections are detected, it is necessary to organize observations of the dynamics of deformations. If the deflection is higher than the standard value (1/200-1/400 of the span) or the deformation continues to increase, it is necessary to strengthen the load-bearing structural elements of the stairs according to the project, having previously taken measures for the safe operation of the stairs.

When cracks are found in the nodes of constructive interfaces of marches, platforms and walls, monitoring of the dynamics of crack changes is established, the causes of their occurrence are determined and appropriate measures are taken to prevent their development.

The most characteristic shortcomings in the operation of staircases are: low air temperature, poor ventilation, dampness of the surfaces of the walls of staircases at the junction of bathrooms and kitchens, insufficient lighting, damage and contamination of wall finishes, lack of glass in windows, non-compliance with sanitary rules for maintaining premises, storage on areas for household items.

When inspecting stairwells, special attention is paid to the serviceability of engineering and technical equipment located on the stairwell, the sealing of windows and doors, the serviceability of lighting and glazing, the tightness of the porches of the loading valves of the garbage chutes, the noise mode, depending on the operation of the elevators. Electrical measuring instruments, switchboards and other disconnecting devices must be permanently locked in cabinets. The keys must be kept by the dispatcher of the housing maintenance organization. Entrances from stairwells to the attic or roof must be locked.

Stairwells are escape routes. It is forbidden to use stairwells for storing materials, equipment and inventory, to arrange pantries and other utility rooms under the flights of stairs. Passages, emergency exits must be free. Staircases during the day should be illuminated through windows, and at nightfall - with the help of electricity.

Proper sanitary condition of the staircase is ensured by regular cleaning. Stair flights and landings are washed at least once a month. Windows, window sills and heaters are swept over at least 1 time in five days, walls - at least 2 times a month.

The stairwell is regularly ventilated. At the same time, window vents or window sashes are opened simultaneously on the first and upper floors. The air temperature in winter should not be lower than 16 0 C. Temperature control is performed annually during spring or autumn inspection in one staircase on the grounds of the first, middle and last floors. The normal temperature and humidity conditions of the staircase are provided during the annual preparation of buildings for operation in the winter. To ensure a tight porch of external entrance doors, springs, sealing gaskets, self-closing devices, door stops are installed. Additional measures are the insulation of walls, ceilings, door panels in the tambour compartment, the installation of a double tambour, which excludes through blowing.

METHODOLOGY FOR ASSESSING THE CONDITION OF STRUCTURES OF WINDOWS, DOORS, LIGHT LIGHTS

The purpose of windows, doors and lanterns is to provide the necessary natural lighting and aeration of the premises, as well as communication with the environment.

These structures are exposed to various influences: atmospheric precipitation, wind loads, variable temperature and humidity conditions, noise, gas, dust, heat and steam flows, solar radiation, etc.

As a result, a number of requirements are imposed on the designs of windows, doors, lanterns:

– good light transmittance;

– thermal insulation;

– air insulation;

Soundproofing.

The main defects of windows, doors, lights include:

- rotting and warping of door fillings;

- violation of interfaces between walls, window and door frames;

– poor-quality fastening of glasses in bindings;

– increased sound transmission of doors, sagging of canvases;

- peeling and destruction of painting, window and door structures;

- leaks around the perimeter of window and door frames;

- gaps of increased width in the porches of bindings and doors;

- destruction of the putty in the folds;

- detachment of glazing beads;

– lack of sealing gaskets;

- insufficient slope and poor-quality sealing of drains;

– freezing of panels of balcony doors;

- penetration of atmospheric moisture through the filling of openings;

- gaps in the joints of individual elements;

icing windows and doors;

- flow through the lanterns;

- violations in the system for removing condensate from the inter-frame space;

– pollution of a glazing;

– unsatisfactory condition of the lamp frame;

– insufficient sealing of joints, etc.

During the operation of buildings, it is necessary to ensure the good condition of windows, doors, skylights, as well as their standard air, heat and sound insulation qualities, to carry out periodic cleaning of translucent filling.

When operating window openings, the following rules must be observed:

– wooden bindings should not be opened in damp rainy weather due to their getting wet and swelling;

- when opening windows, it is necessary to put the sashes of the bindings on fixing devices to prevent breakage of the bindings and loss of glass in the wind;

- when closing the sashes, the bindings should be tightly pulled to the folds - the quarters of the window boxes;

- the latches must be closed to the stop in order to avoid distortion of the bindings;

- window frames must be glazed with whole glass;

- boxes, bindings, window sills must be painted regularly;

– holes or cutouts for water drainage from the outer side of the lower part of the window frames, as well as the outer window tide, must be cleaned of snow, dirt and dust.

Damaged and rotten parts of window frames, sashes, window sills found during the inspection must be replaced with new ones, the wooden parts of window and door fillings should be primed and painted. The bindings that have stuck in the corners of the strapping must be re-glued with the installation of new dowels or metal corners. In the absence of outflows of external bindings, it is necessary to make new ones and install them in the groove on glue and screws with careful painting and puttying.

If condensation water appears on the window sills or between the sills, the water must be removed to prevent rotting of the window sills, sills and boxes. All parts of metal entrance doors should be periodically cleaned of contamination. The plaster damaged and peeled off along the perimeter of the doorways is restored, a door stop is installed on the floor with a gap between the wall and the door.

Fillings of window and door openings that have undergone significant wear should be replaced with new, pre-antiseptic ones. All surfaces in contact with stone walls must be insulated. Paired balcony doors with low thermal properties must be insulated with a gasket between the panels of an effective heat-insulating material (polyurethane foam, mineral felt, etc.).

The gaps between the wall and the frame, creating high air permeability or penetration of atmospheric moisture, must be sealed with special elastic materials (vilaterm, poroizol, tow, tarred or moistened in cement milk) with a compression of at least 30-50%, followed by sealing with cement mortar.

Windows and balcony doors with double glazing in areas with an estimated outside air temperature of minus 30 0 C and below must be supplemented with a third sash during major repairs from the side of the room.

The sealing gaskets installed after painting the bindings in the porch of the window bindings and balcony doors should be replaced every six years, since the coating of the gaskets is not allowed.

Window frames and door panels are painted at least every 6 years. Building lanterns are painted every 5 years.

During the operation of the lamps, it is necessary to check:

- the density of the porch of the bindings and the finishing of the sides with visors made of roofing steel;

- preservation of the geometric shape of the bindings;

– condition and non-failure operation of opening devices;

– the state of the anti-corrosion coating of steel bindings and visors of the side trim;

- wood bindings for decay;

- glass fixing.

All detected defects must be eliminated before the lanterns are closed for the winter. Cleaning the lantern glazing from dust, soot and other contaminants must be carried out at least 2 times a year; clean the glazing of windows in winter only from the inside.

It is necessary to clean the glazing of skylights after a heavy snowfall.

The minimum duration of effective operation of window and door fillings is 15-20 years.

Lesson #25

Topic: Evaluation of the technical and operational characteristics of the state of the facade of the building

During the technical operation of the facade, it is necessary to pay attention to the reliability of fastening of architectural and structural details, which provide static and dynamic resistance to the influence of natural and climatic factors.

The basement is the most humid part of the building due to the impact of atmospheric precipitation, as well as moisture penetrating through the capillaries of the foundation material.

This part of the building is constantly exposed to adverse mechanical stress, which requires the use of durable and frost-resistant materials for the base (Fig. 3.3).

Rice. 3.3. plinth

a - a plinth lined with bricks;

b - plinth lined with natural stone slabs;

c - plinth of large-sized elements;

1 - blind area;

2 - facing;

4 - waterproofing

Cornices, crowning part of the building, divert rain and melt water and perform an architectural and decorative function similar to other architectural and structural elements of the facade of the building. The facades of the building may also have intermediate cornices, belts, sandriks, performing functions similar to those of the main crowning cornice.

The reliability of the enclosing structures of the building depends on the technical condition of the cornices, corbels, pilasters and other protruding parts of the facade.

The part of the outer wall that continues above the roof is the parapet. The upper plane of the parapet is protected by galvanized steel or factory-made concrete slabs to avoid destruction by atmospheric precipitation.

On the roofs of the building, for the safety of repair work, parapet fences are installed in the form of metal gratings and solid brick walls. It is necessary to observe the tightness of the adjunctions of roofing to the elements of parapet railings.

The architectural and structural elements of the facade are also balconies, loggias, bay windows, which contribute to the improvement of performance and appearance building. Depending on the purpose, balconies have different shapes and sizes. With well-executed waterproofing, balconies protect the walls of the building from moisture. Balconies are under conditions of constant atmospheric action, moisture, alternate freezing and thawing, therefore, before other parts of the building fail, collapse. The most critical part of the balconies is the place where slabs or beams are embedded in the wall of the building, since during operation the place of embedding is subjected to intense temperature and humidity effects. On fig. 3.4 shows the connection of the balcony slab with the outer wall. In the buildings of the 50-60s. 20th century usually, crushed stone from a brick battle served as a filler for concrete, which did not provide the required density and frost resistance of balconies. Due to the low corrosion resistance, the structures of balconies with metal beams turned out to be unjustified.

The edges of the balcony slab are especially susceptible to destruction, freezing from three sides, exposed to moisture and corrosion.

Loggia - a platform surrounded on three sides by walls and a fence. In relation to the main volume of the building, the loggia can be built-in and remote.

Rice. 3.4. Pairing a balcony slab with an outer wall

1 - balcony pyaita; 2 - cement mortar; 3 - lining; 4 - heater; 5 - embedded metal element; 6 - pad; 7 - heater; 8 - anchor

Overlapping loggias should provide water drainage from the outer walls of the building. To do this, the floors of the loggias must be made with a slope of 2-3% from the plane of the facade and located below the floor of the adjacent premises, by 50-70 mm. The floor surface of the loggia is covered with waterproofing. The junctions of the balcony and loggia slabs with the facade wall are protected from leakage by placing the edge of the waterproofing carpet on the wall, covering it with two additional layers of waterproofing 400 mm wide and closing it with a galvanized steel apron.

Fences of loggias and balconies should be high enough in order to comply with safety requirements (at least 1-1.2 m) and made mainly deaf, with railings and flower beds.

A bay window is a part of the premises located beyond the plane of the facade wall, which can serve to accommodate vertical communications - stairs, elevators. The bay window increases the area of the premises, enriches the interior, provides additional insolation, and improves lighting conditions. The bay window enriches the shape of the building and serves as an architectural means of shaping the scale of the composition of the facade and its articulation.

During the technical operation of the facade elements, sections of the walls located next to drainpipes, trays, and receiving funnels are subject to thorough inspection. All damaged sections of the finishing layer of the wall must be beaten off and, after identifying and eliminating the cause of damage, restored. In case of weathering, crumbling of fillings of vertical and horizontal joints, as well as destruction of the edges of panels and blocks, it is necessary to inspect the faulty places, fill the joints and restore the broken edges with appropriate materials, after removing the collapsed mortar and carefully caulking the joints with an oiled tourniquet, wiping them with a hard cement mortar with the color of the corrected places to match the color of the wall surfaces.

The facades of buildings are often faced with ceramic tiles, natural stone materials. With poor-quality fastening of the lining with metal staples and cement mortar, they fall out. The reasons for the flaking of the cladding are the ingress of moisture into the seams between the stones and behind the cladding, alternate freezing and thawing.

On facades lined with ceramic tiles, attention should be paid to places where there is swelling of the lining, the exit of individual tiles from the plane of the wall, the formation of cracks, spalls in the corners of the tile; in this case, it is necessary to tap the surface of the entire facade, remove weakly adhering tiles and carry out restoration work.

Facades lined with ceramic products are treated with hydrophobic or other special solutions after cleaning.

Facade defects are often associated with atmospheric pollution, which leads to the loss of the original appearance, sooting and tarnishing of their surface. Effective means of cleaning are the use of sandblasting machines, cleaning with wet rags, etc.

To clean facades finished with glazed ceramic tiles, special compositions are used. Facades of buildings should be cleaned and washed within the time limits established depending on the material, the condition of the surfaces of buildings and operating conditions. It is not allowed to clean architectural details, surfaces of plasters made of soft stone by sandblasting. The facades of wooden non-plastered buildings must be periodically painted with vapor-permeable paints or compounds to prevent decay and in accordance with fire regulations. Improving the appearance of the building can be achieved by their high-quality plastering and painting. Painting of facades must be carried out after the repair of walls, parapets, protruding parts and architectural moldings, entrance devices, sandriks, window sills, etc. is completed.

Painting of metal stairs, elements of fastening of power lines and roof fencing should be done with oil paints after 5-6 years, depending on the operating conditions.

Drainage devices of external walls must have the necessary slopes from the walls to ensure the removal of atmospheric water. With a slope from the walls, steel fasteners are placed. On parts with a slope to the wall, galvanized steel cuffs should be installed tightly adjacent to them at a distance of 5–10 cm from the wall. All steel elements fixed to the wall are regularly painted and protected from corrosion.

It is necessary to systematically check the correct use of balconies, bay windows, loggias, avoiding the placement of bulky and heavy things on them, clutter and pollution.

To prevent the destruction of the edges of the slabs of balconies and loggias, as well as the occurrence of cracks between the slab and the walls due to atmospheric precipitation, a metal drain is installed in a box groove with a width of at least 1.5 of the slab thickness. A metal drain must be led under the waterproofing layer. The slope of the slab of balconies and loggias is at least 3% of the walls of the building with the organization of water drainage with a metal apron or behind an iron plate with a drip, with its removal 3-5 cm; at the end, the drain is embedded in the body of the panel. In the event of an emergency condition of balconies, loggias and bay windows, the entrances to them must be closed and restoration work carried out, which must be carried out according to the project.

During inspections, it is necessary to pay attention to the absence or malfunctioning of the interfaces of drains and the waterproofing layer with the structures, to the loosening of fastening and damage to the fences of balconies and loggias. Damage must be repaired. Destruction of cantilever beams and slabs, chipping of supporting platforms under consoles, delamination and destruction are eliminated during major repairs.

In concreted steel beams, the adhesion strength of concrete to metal is checked. Exfoliated concrete is removed and the protective layer is restored. The location, shape and fastening of the flower boxes should correspond to the architectural design of the building.

Flower boxes and metal railings are painted with weatherproof paints in the color specified in the color scheme of the facade.

Flower boxes are installed on pallets, with a gap of at least 50 mm from the wall. Depending on the materials used for the main structures of balconies and loggias, the minimum duration of their effective operation is 10-40 years.

During operation, it becomes necessary to restore the facade plaster. Defects in the plaster are due to poor quality mortar, work at low temperatures, excessive moisture, etc. In case of minor repair of plaster, cracks are expanded and puttied; in case of significant cracks, the plaster is removed and re-plastered, paying special attention to ensuring adhesion of the plaster layer to the supporting elements.

The main causes of damage to the appearance of buildings are:

- the use in the same masonry of materials that are heterogeneous in strength, water absorption, frost resistance and durability (silicate brick, cinder blocks, etc.);

- different deformability of load-bearing longitudinal and self-supporting end walls;

- the use of silicate brick in rooms with high humidity (baths, saunas, swimming pools, showers, washing, etc.);

- weakening of the bandage;

- thickening of the seams;

- insufficient support of structures;

- freezing solution;

- moistening of cornices, parapets, architectural details, balconies, loggias, plaster walls; technologies for winter masonry, etc.

Lesson #27

Topic: Protecting buildings from premature wear

CORROSION OF THE STRUCTURAL MATERIAL

Impact of aggressive environment for constructiondesigns can lead to corrosion of concrete, reinforcement, embedded parts, as well as to premature wear of stone and concrete structures, can cause destruction and decay of wooden elements and, as a result, a decrease in the bearing capacity of building structures as a whole. Therefore, during the operation of buildings, it is necessary to determine the areas of corrosion damage to concrete, reinforcement, the nature and extent of these damages, as well as to establish the degree of wear of stone structures, etc.

Corrosion is the destruction of materials of building structures under the influence of the environment, accompanied by chemical, physico-chemical and electrochemical processes. Depending on the nature of the corrosion process, chemical and electrochemical corrosion are distinguished. Chemical corrosion is accompanied by irreversible changes in the material of structures as a result of interaction with aggressive environment. Electrochemical corrosion occurs in metal structures under conditions of unfavorable contacts with the atmospheric environment, water, wet soils, and aggressive gases.

The most common are two cathodic processes:

discharge of hydrogen ions by the reaction of reduction of dissolved oxygen

These processes are called hydrogen and oxygen depolarization. Anode and cathode processes occur at any points of the metal surface where cations and electrons interact with the components of the corrosive medium. In iron-carbon alloys, the anode is ferrite, the cathode is cementite or non-metallic inclusions. The secondary reaction of metal corrosion is the interaction of iron cations with hydroxide ions .

Gradually, iron oxide hydrate turns into a compound called rust.

During the operation of buildings, when examining structures, it is necessary to establish the degree and type of damage to the metal by corrosion. The degree of damage to metals is uniform and local (ulcerative). With uniform corrosion, the degree of damage is determined by comparing cross sections affected areas with design. With local corrosion, the size of the ulcers and their number per unit area are determined. Reinforcement corrosion is determined visually by the appearance of longitudinal cracks and rust spots on the surface of the concrete protective layer, as well as by the electrical method.

Building structures are characterized by the simultaneous influence of a corrosive environment and stresses that occur when exposed to permanent and temporary loads, which causes stress corrosion, which leads to a decrease in the strength of the material much earlier than in the absence of load. Depending on the type of load, corrosion is distinguished under a constant tensile load - corrosion cracking and corrosion under alternating, cyclic loads (corrosion fatigue of the structural material). These types of corrosion cause intergranular corrosion, which is more dangerous than uniform and local.

Corrosion of underground structures, which affects pipelines, embedded parts and reinforcement of underground reinforced concrete structures, is associated with the presence of moisture, with dissolved aggressive substances in the soil and soils. The process of corrosion destruction of metal structures proceeds under conditions of insufficient aeration, which causes local corrosion damage. Sections of structures that are less supplied with oxygen become the anode and are destroyed. Therefore, corrosion damage to pipelines often occurs under the carriageway, since the asphalt pavement is less permeable to oxygen than open ground.

To protect against underground corrosion, protective coatings are used, ground and aquatic environment to reduce their corrosivity.

To protect metal structures from corrosion, it is necessary to periodically conduct general and partial inspections of the structure, keep the building structures clean, identify and promptly eliminate areas with premature corrosion, renew the color of metal structures.

Metal structures are exposed to accelerated corrosion in places of direct exposure to moisture, vapors or aggressive gases as a result of a malfunction of enclosing structures; at the junctions of metal columns with the floor. The shoes of the column must be concreted on the blind area not lower than the floor level in order to avoid corrosion of the anchor bolts.

If local damage is found in the paintwork of metal structures, they must be restored as soon as possible.

At least 2 times a year, metal structures must be cleaned of dust and dirt using compressed air. With the massive appearance of signs of destruction of the protective paintwork, it is necessary to paint all structures; the surfaces of the structures prepared for painting are preliminarily cleaned of dust, dirt and the old paint coating.

To organize an acceptable operating environment for building metal structures, it is necessary to organize the removal and removal of aggressive vapors and gases from equipment sources.

The factors causing corrosion of concrete and reinforced concrete structures include: alternate freezing and thawing of concrete, moistening and drying, which is accompanied by shrinkage and swelling deformations, deposition of soluble salts, etc.

The external factors that determine the intensity of corrosion of concrete and reinforced concrete include:

Type of medium and its chemical composition;

Temperature and humidity conditions of the building.

The internal factors that determine the resistance of the material include:

Type of binder in concrete or mortar;

Its chemical and mineral composition;

Chemical composition of aggregates;

Density and structure of concrete;

Type of fittings, etc.

Although concrete is one of the most durable materials, structures made of it, due to the aggressive effects of the environment, careless operation, poor performance, are destroyed before the standard service life (120 - 150 years) for which they are designed. Based on the results of studying the corrosion processes of concrete and the nature of the destruction of reinforced concrete structures in operation, all corrosion processes can be divided into three types.

In the case of type I concrete corrosion, the leading factor is the leaching of soluble constituents of the cement stone and the corresponding destruction of its structural elements. Most often, this type of corrosion occurs when fast-flowing waters act on concrete (leaks in the roof or from pipelines) or when filtering waters with low hardness.

With the intensive development of type II corrosion in concrete, the leading process is the interaction of aggressive solutions with the solid phase of the cement stone during cation exchange and the destruction of the main structural elements of the cement stone. This type includes the processes of concrete corrosion under the action of acid solutions, magnesia salts, ammonium salts, etc.

The main factors in type III corrosion are the processes that occur in concrete when it interacts with an aggressive environment and is accompanied by crystallization of salts in capillaries. At a certain stage in the development of these processes, the growth of crystal formations contributes to the emergence of growing stresses and strains, which leads to the destruction of the concrete structure. The impact of corrosive environments causes the development of physical-mechanical and physical-chemical corrosion processes in concrete, which contributes to a change in the properties of concrete, a redistribution of internal forces in the sections of external elements and a change in the conditions of safety of reinforcing steel.

An essential role in ensuring the reliability and durability of reinforced concrete structures is played by the state of their reinforcement. In dense, undamaged cement-based concrete, steel reinforcement can be completely preserved for a long service life of the structure at any environmental humidity. This is explained by the fact that the presence of an alkaline medium (pH = 12.5) at the metal surface contributes to the preservation of the passive state of steel.

Corrosion of steel in concrete occurs as a result of a violation of its passivity caused by a decrease in alkalinity to pH< 12 при карбонизации или коррозии бетона. Трещины в бетоне облегчают поступление влаги, воздуха и агрессивных веществ из окружающей среды к поверхности арматуры, вследствие чего ее пассивное состояние в местах расположения трещин нарушается. Трещины в железобетонных конструкциях, образующиеся при коррозии арматуры, являются опасными независимо от ширины их раскрытия и свидетельствуют об агрессивности среды, в которой бетон не выполняет своей защитной функции по отношению к арматуре.

Under operating conditions, the most significant parameters affecting the corrosion of reinforcement are the permeability and alkalinity of the concrete of the protective layer. For structures with non-stressed reinforcement, gradual destruction is characteristic, when, as a result of the development of corrosion of the reinforcement under the pressure of a growing layer of rust, the protective layer of concrete cracks and falls off. In the presence of these symptoms, it is necessary to immediately carry out repairs or reinforcement, not allowing the bearing capacity of the structure to be exhausted. The danger of sudden collapse is inherent in structures with prestressing reinforcement made of high-strength steels, which, when corroded, tend to break brittle.

During the operation of reinforced concrete structures, it is often necessary to protect the reinforcement from corrosion processes. Reliable protection reinforcement is the use of shotcrete. It is necessary to clean the damaged areas of the protective layer of the structure, partially or completely expose the reinforcement, clean it from rust, attach it to a bare wire mesh of 2-3 mm in diameter with cells 50-50 mm in size, wash the damaged areas under pressure and perform shotcrete on a wet surface. If the protective layer of concrete is insufficient to protect the reinforcement from corrosion, polyvinyl chloride materials (varnishes, enamels) are applied to the leveled concrete surface. The leveling of the surface is carried out with shotcrete with a layer thickness of at least 10 mm.

Oiling of concrete structures is one of the defects that occur during improper operation of industrial building structures.

As a result of the research, it was found that densely packed and high-strength concrete is not subjected to oiling. Concrete of insufficient density with cracks and shells can be impregnated with various technical oils to a considerable depth, as a result, its strength is reduced by 2 times.

When operating reinforced concrete structures, it is necessary to pay attention to elements that are exposed to high and low temperatures.

The impact of high temperature on reinforced concrete structures leads to a sharp decrease in the adhesion of reinforcement to concrete. When heated to 100°C, the adhesion of smooth reinforcement to concrete decreases by 25%, at 450°C it is completely broken. Heating up to 200°C of reinforced concrete structures with hot-rolled rebar of a periodic profile practically does not reduce adhesion, but at higher temperatures, for example at 450°C, adhesion decreases by 25%.

When operating concrete and reinforced concrete structures, it is necessary:

Carry out measures to reduce the degree of aggressiveness of the environment;

Apply high-density concrete structures, etc.

During operation, it is necessary to ensure sufficient ventilation of the premises to remove aggressive gases, protect building elements from moisture from atmospheric precipitation and groundwater, increase the corrosion resistance of concrete and reinforced concrete structures by surface and volume treatment with surfactants, and install anti-corrosion coatings.