Cost of examination reinforced concrete structures
from 17,000 rub.
Structures built from reinforced concrete are strong and durable objects. If they are built in strict accordance with the project, then in the future there should be no problems with their operation. Even if you are sure that the object is impeccable in terms of the materials used, it is worth regularly monitoring it. The fact is that even the most strong buildings are exposed to aggressive factors and their resistance to corrosion begins to decline.
Our experts at professional level are being investigated by civilians and industrial building and structures in Moscow and recommend ordering an inspection of reinforced concrete structures of buildings:
- Before commissioning.
- Within 2 years after commissioning.
- At least once every 10 years.
- Before the purchase.
- Before redevelopment, reconstruction.
- If the service life of the object has expired.
- After natural disasters and man-made accidents.
Prices for inspection of reinforced concrete structures
In all these situations, the purpose of the survey is to determine technical condition, identifying defects, establishing their causes. Only a detailed study of reinforced concrete objects will achieve these goals. Inspection of the condition of objects should be carried out only by experts who have the right to work in this area, that is, they have received SRO access to carry out activities in the field of construction expertise.
Our advantages
Experienced specialists
Our specialists, who have been working in this field for many years, have a full range of practical knowledge
Quality of work
The work takes a minimum of time, while the quality always remains at its best
Wide range of services
Our company specializes in providing a range of services
Affordable prices with high quality work
How we are working?
Although reinforced concrete structures are varied, their examination is carried out according to a single algorithm:
- Preparation and study of technical and design documentation.
- Field work. They are carried out directly on site. Experts conduct a visual, detailed examination. They on at this stage They use ultra-precise equipment that allows us to determine the strength and other characteristics of materials.
- Laboratory tests of those samples that were taken at the previous stage.
- Analytical work with the results obtained, identifying the causes of defects. Note that the most common causes of destruction of reinforced concrete structural elements are leaching, carbonization, rust, etc.
- Compilation technical report and issuing it to the customer.
By calling our experts, you will clarify the prices for the service: they will name preliminary tariffs for the inspection of reinforced concrete structures of buildings. The exact amount will be calculated after reviewing the terms of reference.
Research Group "Safety and Reliability"
Construction expertise, Building inspection, Energy audit, Land management, Design
It is no secret that during the construction and operation of buildings and structures, unacceptable deflections, cracks, and damage occur in reinforced concrete structures. These phenomena can be caused either by deviations from the design requirements during the manufacture and installation of these structures, or by design errors.
An inspection of reinforced concrete structures is called upon to assess the physical condition of the structure, establish the causes of damage, and determine the actual strength, crack resistance and rigidity of the structure. It is important to correctly assess the load-bearing capacity of structures and develop recommendations for their further exploitation. And this is only possible as a result of detailed field study.
The need for such an examination arises in cases of studying the peculiarities of the operation of structures and structures in difficult conditions, during the reconstruction of a building or structure, in the process of conducting an examination, if there are deviations from the design in the structures, and in a number of other cases.
The inspection of reinforced concrete structures consists of several stages. On initial stage a preliminary inspection of structures is carried out to identify the presence of completely or partially destroyed areas, ruptures of reinforcement, damage to concrete, displacement of supports and elements in prefabricated structures.
At the next stage, there is familiarization with the design and technical documentation, followed by a direct examination of reinforced concrete structures, which makes it possible to obtain a real picture of the state of the structures and their operation under operating conditions. Depending on the tasks, the strength of concrete can be assessed non-destructive methods, as well as clarifying the actual reinforcement, which consists of collecting data on the actual state of the reinforcement and comparing them with the parameters contained in the working drawings, as well as selectively checking the compliance of the actual reinforcement with the design one.
Since the actual loads may differ significantly from the design ones, an analysis of the stressed state of structures is carried out. For this purpose, actual loads and impacts are determined. If necessary, full-scale testing may be a continuation. Upon completion, a construction and technical conclusion is issued.
We work according to this principle:
1 You dial our number and ask questions that are important to you, and we give comprehensive answers to them.
2 After analyzing your situation, we determine a list of questions that our experts should answer. An agreement to conduct an inspection of reinforced concrete structures can be concluded either in our office or directly at your site.
3 We will come to you at a time convenient for you and conduct an inspection of reinforced concrete structures.
After carrying out the work, using special instruments (destructive and non-destructive testing), you will receive a written construction and technical report, which will reflect all the defects, the reasons for their occurrence, a photo report, design calculations, assessment of refurbishment, conclusions and recommendations.
The cost of examining reinforced concrete structures starts from 15,000 rubles.
The time frame for receiving the conclusion is from 3 working days.
4 Many clients require a visit from a specialist without a subsequent conclusion. A construction and technical expert will conduct an inspection of reinforced concrete structures, based on the results of which he will give an oral report with conclusions and recommendations on site. You can decide whether to draw up a written conclusion based on the results of the study later.
The cost of our expert’s visit starts from 7,000 rubles.
5 We have designers and constructors in our company who, based on our conclusion, can develop a project for eliminating deficiencies and a project for strengthening structures.
Inspection of concrete and reinforced concrete structures is an important part of the inspection of a building or structure as a whole.
In this article we reveal an approach to the inspection of concrete and reinforced concrete structures. The longevity of the building’s operation depends on the qualified performance of this part of the building inspection.
Inspections of concrete and reinforced concrete structures of a building are carried out both as part of regular inspections during operation, and before the addition or reconstruction of a building, before purchasing a building, or when structural defects are identified.
Correct assessment of the condition of concrete and reinforced concrete structures allows us to reliably assess their load-bearing capacity, which will ensure further safe operation or superstructure/extension.
Assessment of the technical condition of concrete and reinforced concrete structures according to external signs carried out on the basis of:
- definitions geometric dimensions structures and their sections; This data is necessary for verification calculations. For an experienced specialist, sometimes it is enough to visually assess the clearly insufficient dimensions of the structure.
- comparison of actual dimensions of structures with design dimensions; The actual dimensions of the structures play a very important role, because dimensions are directly related to calculations bearing capacity. One of the tasks of designers is to optimize dimensions in order to avoid overspending building materials, and, accordingly, increased construction costs. The myth that designers include multiple safety margins in their calculations is actually a myth. Reliability and safety factors are of course present in the calculations, but they are in accordance with SNiP for design 1.1-1.15-1.3. those. not so much.
- compliance of the actual static diagram of the operation of structures adopted in the calculation; The actual diagram of the loads of structures is also very important, because If the design dimensions are not observed, due to construction defects, additional loads and bending moments may occur in structures and assemblies, which sharply reduces the load-bearing capacity of structures.
- the presence of cracks, spalls and destruction; The presence of cracks, spalls and destruction is an indicator of unsatisfactory performance of structures, or indicates poor quality of construction work.
- location, nature of cracks and width of their opening; Based on the location of the cracks, their nature and the width of their opening, a specialist can determine the probable cause of their occurrence. Some types of cracks are allowed by SNiP in reinforced concrete structures, others may indicate a decrease in the load-bearing capacity of the building structure.
- state protective coatings; Protective coatings are so called because they must protect building structures from adverse and aggressive influences. external factors. Violation of protective coatings, of course, will not lead to instant destruction of the building structure, but will affect its durability.
- deflections and deformations of structures; The presence of deflections and deformations can give a specialist the opportunity to assess the performance of a building structure. Some bearing capacity calculations building structures are carried out according to the maximum permissible deflections.
- signs of impaired adhesion of reinforcement to concrete; The adhesion of reinforcement to concrete is very important, because concrete does not work in bending, but only in compression. Bending work in reinforced concrete structures is provided by reinforcement, which can be prestressed. The lack of adhesion between reinforcement and concrete indicates that the flexural load-bearing capacity of the reinforced concrete structure has decreased.
- presence of reinforcement rupture; Reinforcement ruptures indicate a decrease in load-bearing capacity up to the category of emergency condition.
- anchorage conditions of longitudinal and transverse reinforcement; Anchoring of longitudinal and transverse reinforcement provides correct work reinforced concrete building structure. Violation of anchorage can lead to an emergency condition.
- degree of corrosion of concrete and reinforcement. Corrosion of concrete and reinforcement reduces the load-bearing capacity of a reinforced concrete structure, because the thickness of concrete and the diameter of reinforcement decrease due to corrosion. The thickness of concrete and the diameter of the reinforcement are one of the important quantities in calculating the load-bearing capacity of a reinforced concrete structure.
The size (width) of the opening of cracks in concrete is measured in areas of their greatest opening and at the level of the reinforcement of the tensile zone of the element, because this gives the most complete idea of the performance of the building structure.
The degree of crack opening is determined in accordance with SNiP 52-01-2003.
Cracks in concrete are analyzed from the point of view of structural features and the stress-strain state of the reinforced concrete structure. Sometimes cracks appear due to violations of manufacturing, storage and transportation technology.
Therefore, the task of a specialist (expert) is to determine the probable cause of cracks and assess the impact of these cracks on the load-bearing capacity of the building structure.
During the inspection of concrete and reinforced concrete structures, specialists determine the strength of concrete. For this purpose, non-destructive testing methods are used or laboratory tests are carried out and are guided by the requirements of GOST 22690, GOST 17624, SP 13-102-2003. When conducting an inspection, we use several non-destructive testing devices (impulse-impulse method IPS-MG4, ONICS; ultrasonic method UZK MG4.S; tear-off device with chipping POS, and also, if necessary, we use a “Kashkarov hammer”). We give a conclusion about the actual strength characteristics based on the readings of at least two instruments. We also have the opportunity to conduct research on selected samples in the laboratory.
Assessment of the technical condition of structures based on external signs is based on determining the following factors:
- geometric dimensions of structures and their sections;
- the presence of cracks, spalls and destruction;
- condition of protective coatings (paint and varnish, plasters, protective screens, etc.);
- deflections and deformations of structures;
- violation of the adhesion of reinforcement to concrete;
- presence of reinforcement rupture;
- anchorage conditions of longitudinal and transverse reinforcement;
- degree of corrosion of concrete and reinforcement.
When determining the geometric parameters of structures and their sections, all deviations from their design position are recorded. Determination of the width and depth of crack opening should be carried out according to the recommendations indicated above.
It is recommended to measure the crack opening width primarily in places of maximum crack opening and at the level of the tensile zone of the element. The degree of crack opening is compared with regulatory requirements according to limit states of the second group, depending on the type and operating conditions of structures. It is necessary to distinguish between cracks, the appearance of which is caused by stresses manifested in reinforced concrete structures during manufacturing, transportation and installation, and cracks caused by operational loads and environmental influences.
Cracks that appeared during the period before the operation of the facility include: technological, shrinkage, caused by rapid drying of the surface layer of concrete and reduction in volume, as well as cracks from concrete swelling; caused by uneven cooling of concrete; cracks that appeared in prefabricated reinforced concrete elements during storage, transportation and installation, in which the structures were subjected to force effects from their own weight according to schemes not provided for by the design.
Cracks that appeared during the operational period include: cracks that arose as a result of temperature deformations due to violations of the device requirements expansion joints; caused by uneven sedimentation of the pound base, which may be due to violation of the requirements of the sedimentary structure expansion joints, carrying out earthworks in close proximity to foundations without special measures; caused by force impacts exceeding the load-bearing capacity of reinforced concrete elements.
Force-type cracks must be considered from the point of view of the stress-strain state of the reinforced concrete structure.
The most common types of cracks in reinforced concrete structures are:
- a) in bending elements operating according to a beam scheme (beams, purlins), cracks appear, perpendicular (normal) to the longitudinal axis, due to the appearance of tensile stresses in the zone of action of maximum bending moments, inclined to the longitudinal axis, caused by the main tensile stresses in the zone of action of shearing forces and bending moments (Fig. 2.32).
Rice. 2.32.
working according to the beam scheme
- 1 - normal cracks in the zone of maximum bending moment;
- 2 - inclined cracks in the zone of maximum transverse force;
- 3 - cracks and crushing of concrete in the compressed zone.
Normal cracks have a maximum opening width in the outermost tensile fibers of the element's cross-section. Oblique cracks begin to open in the middle part of the side faces of the element - in the zone of maximum tangential stresses, and then develop towards the stretched face.
The formation of inclined cracks at the supporting ends of beams and girders is due to their insufficient load-bearing capacity along inclined sections.
Vertical and inclined cracks in the spans of beams and girders indicate their insufficient bearing capacity in terms of bending moment.
The crushing of concrete in the compressed zone of sections of bending elements indicates the exhaustion of the bearing capacity of the structure;
b) cracks may occur in the slabs:
in the middle part of the slab, having a direction across the working span with maximum opening on the lower surface of the slab;
on supporting sections, directed across the working span with maximum opening on the upper surface of the slab;
radial and end, with possible loss of the protective layer and destruction of the concrete slab;
along the reinforcement along the lower plane of the wall.
Cracks in the supporting sections of the slabs across the working span indicate insufficient bearing capacity for bending support moment.
Characteristic is the development of cracks of force origin on the lower surface of slabs with different aspect ratios (Fig. 2.33). In this case, the concrete of the compressed zone may not be damaged. Concrete collapse of the compressed zone indicates the danger of complete destruction of the slab;
Rice. 2.33. Characteristic cracks on the lower surface of the slabs: a - working according to the beam scheme at / 2 //, > 3; b - supported along the contour at / 2 //, 1.5
c) vertical cracks form on the edges of the columns and horizontal cracks in the columns.
Vertical cracks on the edges of columns can appear as a result of excessive bending of reinforcement bars. This phenomenon can occur in those columns and their areas where clamps are rarely installed (Fig. 2.34).
Rice. 2.34.
Horizontal cracks in reinforced concrete columns do not pose an immediate danger if their width is small, however, through such cracks, humidified air and aggressive reagents can enter the reinforcement, causing corrosion of the metal,
The appearance of longitudinal cracks along the reinforcement in compressed elements indicates destruction associated with loss of stability (buckling) of longitudinal compressed reinforcement due to an insufficient amount of transverse reinforcement;
- d) the appearance in bending elements of a transverse crack, perpendicular to the longitudinal axis of the element, passing through the entire section (Fig. 2.35), may be associated with the influence of an additional bending moment in the horizontal plane, perpendicular to the plane the action of the main bending moment (for example, from horizontal forces arising in crane beams). Cracks in tensile reinforced concrete elements have the same nature, but the cracks are visible on all faces of the element and encircle it;
- e) cracks in supporting areas and ends of reinforced concrete structures.
Detected cracks at the ends of prestressed elements, oriented along the reinforcement, indicate a violation of the anchorage of the reinforcement. This is also evidenced by inclined cracks in the support areas, crossing the area where prestressed reinforcement is located and extending to the lower edge of the support edge (Fig. 2.36);
f) lattice elements of braced reinforced concrete trusses can experience compression, tension, and in support nodes - action
cutting forces. Typical damage
Rice. 2.36.
- 1 - in case of violation of the anchorage of stressed reinforcement;
- 2 - at
insufficiency
indirect
reinforcement
Rice. 2.35.
planes
The dynamics during the destruction of individual sections of such trusses are shown in Fig. 2.37. In addition to cracks, 2 (Fig. 2.38) damage of types 1, 2, 4 may occur in the support unit. The appearance of horizontal cracks in the lower prestressed belt of type 4 (see Fig. 2.37) indicates the absence or insufficiency of transverse reinforcement in the compressed concrete. Normal (perpendicular to the longitudinal axis) cracks of type 5 appear in tensile rods when the crack resistance of the elements is not ensured. The appearance of damage in the form of type 2 flanges indicates the exhaustion of the concrete strength in certain areas of the compressed belt or on the support.
Rice. 2.37.
pre-stressed belt:
1 - inclined crack at the support unit; 2 - spalling of flanges; 3 - radial and vertical cracks; 4 - horizontal crack; 5 - vertical (normal) cracks in tensile elements; 6 - inclined cracks in the compressed chord of the truss; 7 - cracks in the lower chord assembly
Defects in the form of cracks and concrete spalling along the reinforcement of reinforced concrete elements can also be caused by corrosion destruction of the reinforcement. In these cases, the adhesion of the longitudinal and transverse reinforcement to the concrete is disrupted. Loss of adhesion between reinforcement and concrete due to corrosion can be
Rice. 2.38.
install by tapping the concrete surface (voids can be heard).
Longitudinal cracks along the reinforcement with disruption of its adhesion to concrete can also be caused by temperature stresses during the operation of structures with systematic heating above 300°C or the consequences of a fire.
In bending elements, as a rule, an increase in deflections and rotation angles leads to the appearance of cracks. Deflections of bending elements of more than 1/50 of the span with a crack opening width in the tensile zone of more than 0.5 mm can be considered unacceptable (emergency). The values of maximum permissible deflections for reinforced concrete structures are given in table. 2.10.
Determination and assessment of the condition of coatings of reinforced concrete structures should be carried out according to the methodology set out in GOST 6992-68. In this case, the following main types of damage are recorded: cracking and peeling, which are characterized by the depth of destruction of the top layer (before the primer), bubbles and corrosion foci, characterized by the size of the foci (diameter), mm. Square individual species coating damage is expressed approximately as a percentage relative to the entire painted surface of the structure (element).
The effectiveness of protective coatings when exposed to an aggressive environment is determined by the state of the concrete structures after removal of the protective coatings.
During visual inspections, an approximate assessment of the strength of concrete is made. The method is based on tapping the surface of the structure with a hammer weighing 0.4-0.8 kg directly on a cleaned mortar area of concrete or on a chisel installed perpendicular to the surface of the element. A louder sound when tapped corresponds to stronger and denser concrete. To obtain reliable data on the strength of concrete, the methods and instruments given in the section on strength control should be used.
If there are wet areas and surface efflorescence on the concrete of structures, the size of these areas and the reason for their appearance are determined. The results of a visual inspection of reinforced concrete structures are recorded in the form of a map of defects plotted on schematic plans or sections of the building, or tables of defects are drawn up with recommendations for classification.
VALUE OF MAXIMUM ALLOWABLE DEFLECTIONS OF REINFORCED CONCRETE
CONSTRUCTIONS
Table 2.10
Note. Under constant, long-term and short-term loads, the deflection of beams and slabs should not exceed 1/150 of the span and I/75 of the cantilever overhang.
cation of defects and damage with assessment of the category of condition of structures.
To assess the nature of the corrosion process and the degree of exposure to aggressive environments, three main types of concrete corrosion are distinguished.
Type I includes all corrosion processes that occur in concrete under the action of liquid media (aqueous solutions) capable of dissolving the components of cement stone. The constituents of the cement stone are dissolved and removed from the cement stone.
Type II corrosion includes processes in which chemical interactions - exchange reactions - occur between the cement stone and the solution, including the exchange of cations. The resulting reaction products are either easily soluble and removed from the structure as a result of diffusion or filtration flow, or are deposited in the form of an amorphous mass that does not possess astringent properties and does not affect the further destructive process.
This type of corrosion is represented by processes that occur when solutions of acids and certain salts act on concrete.
Type III corrosion includes all those concrete corrosion processes, as a result of which reaction products accumulate and crystallize in the pores and capillaries of concrete. At a certain stage of development of these processes, the growth of crystal formations causes the occurrence of increasing stresses and deformations in the enclosing walls, and then leads to destruction of the structure. This type may include corrosion processes under the action of sulfates associated with the accumulation and growth of crystals of hydrosulfoaluminate, gypsum, etc. The destruction of concrete in structures during their operation occurs under the influence of many chemical and physical-mechanical factors. These include heterogeneity of concrete, increased stress in the material of various origins, leading to micro-tears in the material, alternating wetting and drying, periodic freezing and thawing, sudden temperature changes, exposure to salts and acids, leaching, disruption of contacts between cement stone and aggregates, corrosion steel reinforcement, destruction of aggregates under the influence of cement alkalis.
The complexity of studying the processes and factors causing the destruction of concrete and reinforced concrete is explained by the fact that, depending on the operating conditions and service life of structures, many factors simultaneously act, leading to changes in the structure and properties of materials. For most structures in contact with air, carbonization is a characteristic process that weakens the protective properties of concrete. Carbonation of concrete can be caused not only by carbon dioxide, present in the air, but also other acidic gases contained in the industrial atmosphere. During the carbonization process, carbon dioxide from the air penetrates into the pores and capillaries of concrete, dissolves in the pore fluid and reacts with calcium oxide hydroaluminate, forming slightly soluble calcium carbonate. Carbonation reduces the alkalinity of the moisture contained in concrete, which leads to a decrease in the so-called passivating (protective) effect of alkaline media and corrosion of reinforcement in concrete.
To determine the degree of corrosion destruction of concrete (degree of carbonization, composition of new formations, structural damage to concrete), physicochemical methods are used.
Study chemical composition new formations that have arisen in concrete under the influence of an aggressive environment are carried out using differential thermal and X-ray structural methods, performed in laboratory conditions on samples taken from operating structures. The study of structural changes in concrete is carried out using a hand-held magnifying glass, which gives a slight magnification. Such an inspection allows you to examine the surface of the sample, identify the presence of large pores, cracks and other defects.
Using the microscopic method it is possible to detect mutual arrangement and the nature of the adhesion of cement stone and aggregate grains; state of contact between concrete and reinforcement; shape, size and number of pores; size and direction of cracks.
The depth of carbonation of concrete is determined by changes in the pH value.
If the concrete is dry, wet the chipped surface clean water, which should be enough so that a visible film of moisture does not form on the surface of the concrete. Excess water is removed with clean filter paper. Wet and air-dry concrete does not require moisture.
A 0.1% solution of phenolphthalein in ethyl alcohol is applied to the concrete chip using a dropper or pipette. When pH changes from 8.3 to 14, the color of the indicator changes from colorless to bright crimson. A fresh fracture of a concrete sample in the carbonized zone after applying a phenolphthalein solution to it has grey colour, and in the non-carbonized zone it acquires a bright crimson color.
Approximately a minute after applying the indicator, measure with a ruler, with an accuracy of 0.5 mm, the distance from the surface of the sample to the border of the brightly colored zone in the direction normal to the surface. The measured value is the depth of carbonation of the concrete. In concretes with a uniform pore structure, the border of the brightly colored zone is usually located parallel to the outer surface. In concretes with an uneven pore structure, the carbonization boundary may be tortuous. In this case, it is necessary to measure the maximum and average depth of carbonation of concrete. Factors influencing the development of corrosion of concrete and reinforced concrete structures are divided into two groups: those related to the properties of the external environment - atmospheric and groundwater, production environment, etc., and due to the properties of materials (cement, aggregates, water, etc.) of structures.
For operating structures it is difficult to determine how many and what chemical elements left in surface layer, and whether they are able to continue their destructive action. When assessing the danger of corrosion of concrete and reinforced concrete structures, it is necessary to know the characteristics of concrete: its density, porosity, number of voids, etc.
The corrosion processes of reinforced concrete structures and methods of protection against it are complex and varied. The destruction of reinforcement in concrete is caused by the loss of protective properties concrete and access to moisture, air oxygen or acid-forming gases. Corrosion of reinforcement in concrete is an electrochemical process. Since reinforcing steel is heterogeneous in structure, as is the medium in contact with it, all conditions are created for the occurrence of electrochemical corrosion.
Corrosion of reinforcement in concrete occurs when the alkalinity of the electrolyte surrounding the reinforcement decreases to a pH equal to or less than 12, due to carbonization or corrosion of concrete.
When assessing the technical condition of reinforcement and embedded parts affected by corrosion, it is first necessary to establish the type of corrosion and the affected areas. After determining the type of corrosion, it is necessary to establish the sources of influence and the causes of corrosion of the reinforcement. The thickness of corrosion products is determined with a micrometer or using instruments that measure the thickness of non-magnetic anti-corrosion coatings on steel (for example, ITP-1, MT-ZON, etc.).
For periodic profile reinforcement, the residual expression of reefs after stripping should be noted.
In places where corrosion products have become well preserved, it is possible to roughly judge the depth of corrosion by their thickness using the ratio
where 8 a. - average depth of continuous uniform corrosion of steel; - thickness of corrosion products.
Identification of the state of the reinforcement of elements of reinforced concrete structures is carried out by removing the protective layer of concrete with exposure of the working and installation reinforcement.
The reinforcement is exposed in places where it is most weakened by corrosion, which are revealed by the peeling of the protective layer of concrete and the formation of cracks and rusty stains located along the reinforcement rods. The diameter of the reinforcement is measured with a caliper or micrometer. In places where the reinforcement has been subjected to intense corrosion, which has caused the protective layer to fall off, it is thoroughly cleaned of rust until a metallic sheen appears.
The degree of corrosion of reinforcement is assessed by the following signs: nature of corrosion, color, density of corrosion products, affected surface area, cross-sectional area of reinforcement, depth of corrosion lesions.
With continuous uniform corrosion, the depth of corrosion lesions is determined by measuring the thickness of the rust layer, with ulcerative corrosion - by measuring the depth of individual ulcers. In the first case sharp knife The rust film is separated and its thickness is measured with a caliper. It is assumed that the depth of corrosion is equal to either half the thickness of the rust layer or half the difference between the design and actual diameters of the reinforcement.
In case of pitting corrosion, it is recommended to cut out pieces of reinforcement, remove rust by etching (immersing the reinforcement in a 10% solution of hydrochloric acid containing 1% urotropine inhibitor) followed by rinsing with water. Then the fittings must be immersed for 5 minutes in a saturated solution of sodium nitrate, removed and wiped. The depth of the ulcers is measured with an indicator with a needle mounted on a tripod.
The depth of corrosion is determined by the indicator arrow reading as the difference in readings at the edge and bottom of the corrosion pit. When identifying areas of structures with increased corrosive wear associated with local (concentrated) exposure to aggressive factors, it is recommended to first pay attention to the following elements and components of structures:
- supporting units of rafter and sub-rafter trusses, near which water inlet funnels are located internal drain;
- the upper chords of the trusses at the points where aeration lamps and wind deflector posts are connected to them;
- the upper chords of the rafter trusses, along which the roof valleys are located;
- truss support units located inside brick walls;
- the upper parts of columns located inside brick walls;
- the bottom and bases of columns located at or below the floor level, especially during wet cleaning in the room (hydraulic wash);
- sections of columns of multi-storey buildings passing through the ceiling, especially when wet dusting indoors;
- sections of covering slabs located along the valleys, at the funnels of the internal drainage system, at the external glazing and the ends of the lanterns, at the ends of the building.
