Cracks that appear on the walls of a building not only spoil the aesthetics of the building, but are also a sign of serious architectural problems.
If such a situation arises, be sure to notify the company responsible for operating the structure.
Specialists must conduct a technical assessment of the structure, establish the degree of safety for further use and approve a list of measures to eliminate the problem.
During the inspection, the age of the damage is taken into account. Beacons are also installed on wall cracks to determine the dynamics of destruction.
Installation of beacons to determine the size of cracks in walls
The degree of danger of a crack that appears is determined by the location of its formation:
- on load-bearing walls - create serious emergency situations;
- on partitions - are local in nature.
The problem area of the structure is monitored using different types of beacons. Monitoring is also used in buildings identified as emergency or with limited functionality. The development of the resulting destruction is also monitored in structures near which active construction work is taking place or reconstruction is being carried out.
Point control method for cracks on walls 
Electronic sensors and monitoring systems 
Gypsum beacons 
Plate beacons
The main purpose of observation is to record in a special log all changes in the parameters of cracks that appear.
The following indicators are needed:
- for a correct assessment of the technical condition of the building;
- decisions on the possibility of further operation;
- the need and complexity of repair work;
- eliminating factors that destroy the building.
When choosing a suitable observation method, they take into account the urgency of obtaining information, the accuracy of the results, the reliability of the method itself and the complexity of the upcoming work.
Types of beacons and features of use
Electronic models
The work uses electronic sensors that can transmit information at a distance. With the help of such beacons on cracks, accurate results of damage to walls or partitions are obtained.
The procedure is expensive and requires the use of several sensors that measure the displacement of the structure in different directions. But such observations are carried out for no more than 15 days, and the results are recorded with an accuracy of hundredths.
Plaster marks on walls
They are considered the most accessible way to monitor the resulting destruction. Before installation, the damaged surface will need to be leveled. If the structure continues to deform, cracks will form on the lighthouse. In this case, control marks are installed nearby.
This takes into account:
- negative reaction of gypsum to the influence of low temperatures and natural factors;
- the ability of marks to collapse on their own;
- high error of the obtained results.
The resulting measurement accuracy is also affected by the unevenness of the wall on which the crack has formed. Each tag is assigned a serial number and date. The results are recorded in a journal.
Massuras 
How to prevent cracks from spreading
Measurements using plate fixtures
Such beacons are installed using epoxy glue or screwed using dowels. Models are equipped with a signal scale for taking measurements. The scale contains two axes and additional information, allowing you to fully examine damage in all directions. The measurement results are recorded to the nearest hundredth (in millimeters).
In terms of the ratio of the cost of the device and the effectiveness of the event, this method is considered the most optimal. Also, plate beacons are convenient to use.
Point control method
In the area of displacement of the structure, control points are determined and marked with ordinary dowels or special beacons that are inconspicuous on the wall. In this case, the surface in the problem area does not need to be pre-cleaned from finishing. This method allows one to observe the development of a split in any direction.
The accuracy of the result depends on the error of the instruments used to perform control measurements. Dowels or other devices are rigidly fixed to the plane and do not fall out during the research period.
Massuras
They are a clock mechanism with a high-precision measuring scale. They are visual devices from which readings can be easily taken, and the result allows you to quickly navigate the changes taking place. Considering the high cost of devices and the same probability of vandalism, sentry beacons are used when carrying out control measurements.
Inspection of cracks in walls caused by overload provides complete information about the condition of the masonry. An initial inspection of cracks caused by uneven settlement of the foundation and temperature changes makes it possible to determine their origin and opening, but does not make it possible to determine whether deformation has stabilized or not. To get an idea of the dynamics of crack development and their stabilization, beacons are installed on the walls. At least two beacons are placed on each crack; one is at the place of maximum development of the crack, the other is at the place where its development begins. Lighthouses are most often made of plaster (alabaster). Cement beacons are sometimes made on the outer surfaces of walls. Lighthouses can also be glass or metal.
Gypsum (cement) Beacons are installed on a wall surface cleared of plaster. Beacons must have widening at the ends (figure eight type) ( rice. 1.3,A). The thickness of the gypsum beacon near the crack should be minimal (6...8 mm).
Glass the beacons also have widening at the ends and are fastened along the perimeter to the wall surface with gypsum mortar ( rice. 1.3,b).
Rice. 1.3. Schemes of beacons on cracks:
a - gypsum (cement); b - glass; c, d - metal: 1 - crack; 2 - plaster; 3 - wall; 4 - gypsum, mortar
Metal lighthouses are made from two strips of roofing steel ( rice. 1.3, c) and glued to the cleaned wall surface with synthetic glue or nailed. The narrow strip should overlap the wide strip. The lighthouse made of galvanized steel is painted with oil paint. On a wider strip, marks are applied every 1 mm.
On rice. 1.3,d shows a version of a metal beacon made of roofing steel. The rectangular plate is initially painted red. After installing the second (U-shaped) plate, the entire lighthouse is painted with white paint so that the red paint is retained only under the U-shaped plate. The mutual displacement of the plates is detected by the trace of different paints and measured with a metal ruler with a beveled edge.
Measurement accuracy 0.2...0.3 mm. Lighthouses are marked with a number and date. The data is entered into a special journal of observations of lighthouses.
With the help of gypsum (cement) beacons it is possible to establish only the fact of continued development of deformations (formation of a crack in the beacon) and measure the opening of the crack.
Metal beacons with marks make it possible to identify the values of both opening and closing cracks.
Opening strains and displacements along the crack can be determined with a messura indicator with a division value of 0.1 mm, using steel pins with a centering device (drilled or cored recesses). The pins are sealed on both sides of the crack at a distance of 60...100 mm from it. If a metal beacon is installed in a hard-to-reach place, then readings on its scale can be taken from a distance using binoculars, a theodolite or a spotting scope.
It is necessary to monitor not only the opening of cracks, but also their elongation. For this purpose, after the crack has lengthened, a new beacon is placed at its end. When analyzing the behavior of lighthouses, it should be kept in mind that a crack in the masonry becomes a natural expansion joint. The beacon installed on it will record not only deformations from uneven settlement of the foundation, but also temperature. Therefore, with temperature changes, even in the absence of uneven settlement of the foundations, hairline cracks will almost always appear in the lighthouse.
If there are cracks in the load-bearing structures of buildings and structures, it is necessary to organize systematic monitoring of their condition and possible development in order to find out the nature of the deformations of the structures and the degree of their danger for further operation.
Monitoring the development of cracks is carried out according to a schedule, which in each individual case is drawn up depending on the specific conditions.
Cracks are identified by inspecting the surfaces of structures, as well as selective removal of protective or finishing coatings from structures.
It is necessary to determine the position, shape, direction, distribution along the length, width of the opening, depth, and also determine whether their development continues or has stopped.
A beacon is installed on each crack, which breaks when the crack develops. The beacon is installed in the place of greatest development of the crack.
When observing the development of cracks along the length, the ends of the cracks during each inspection are fixed with transverse strokes applied with paint or a sharp instrument on the surface of the structure. The date of inspection is indicated next to each stroke.
The location of the cracks is schematically marked on the drawings of the general view of the walls of the building, noting the numbers and date of installation of the beacons. For each crack, a schedule of its development and opening is drawn up.
Cracks and beacons are periodically inspected in accordance with the observation schedule, and based on the inspection results, a report is drawn up, which indicates: the date of inspection, a drawing with the location of cracks and beacons, information about the condition of cracks and beacons, information about the absence or appearance of new cracks and installation on them lighthouses.
The width of crack opening is usually determined using an MPB-2 microscope with a scale division of 0.02 mm, a measurement limit of 6.5 mm and a MIR-2 microscope with a measurement scale of 0.015 to 0.6 mm, as well as a magnifying glass with scale division (Brinell loupes ) (Fig. 1) or other devices and tools that provide measurement accuracy of at least 0.1 mm.
Rice. 1. Instruments for measuring crack opening a - reading microscope MPB-2, b - measuring the crack opening width with a magnifying glass: 1 - crack; 2 - division of the magnifying glass scale; c – dipstick
The depth of cracks is determined using needles and wire probes, as well as using ultrasonic devices such as UKB-1M, Beton-3M, UK-10P, etc. The scheme for determining the depth of cracks using ultrasonic methods is shown in Fig. 2.
Rice. 2. Determination of the depth of cracks in the structure 1 - emitter; 2 – receiver
When using the ultrasonic method, the depth of the crack is determined by changing the transit time of pulses both during through sounding and by the longitudinal profiling method, provided that the plane of crack formation is perpendicular to the line of sounding. The depth of the crack is determined from the relations:
where h is the depth of the crack (see Fig. 2); V is the speed of propagation of ultrasound in the area without cracks, μ/s; ta, te - time of passage of ultrasound in the area without a crack and with a crack, s; a - measurement base for both sections, see
An important tool in assessing deformation and crack development are beacons: they make it possible to establish a qualitative picture of deformation and their magnitude.
The lighthouse is a plate 200-250 mm long, 40-50 mm wide, 6-10 m high, made of gypsum or cement-sand mortar, placed across a crack, or two glass or metal plates, each with one end fixed on opposite sides of the crack , or lever system. The rupture of the beacon or the displacement of the plates relative to each other indicate the development of deformations.
The lighthouse is installed on the main material of the wall, having first removed the plaster from its surface. It is also recommended to place beacons in pre-cut grooves (especially when installing them on a horizontal or inclined surface). In this case, the grooves are filled with gypsum or cement-sand mortar.
Beacons are inspected a week after their installation, and then once a month. In case of intense cracking, daily monitoring is required.
The opening width of cracks during observation is measured using crack gauges or crack gauges. The design of the gap gauge or crack gauge can be different depending on the width of the crack or seam between the elements, the type and operating conditions of the structures.
The simplest solution is a plate beacon (see Fig. 3). It consists of two metal, glass or plexiglass plates that have marks and are fixed to the solution so that when a crack opens, the plates slide over one another. The edges of the plates should be parallel to each other. After attaching the plates to the structure, mark on them the number and date of installation of the beacon. By measuring the distance between the risks, the size of the crack opening is determined.
Rice. 3. Plate beacon made of two painted plates 1 - plate painted white; 2 - plate, painted red; 3 - gypsum tiles; 4 – crack
And about. Head of the Department of Engineering Surveys and Inspection of Building Structures Belskaya Yu.S.
Methods for observing cracks in stone and concrete structures
Cracks in buildings and structures can form for various reasons. They may simply spoil the appearance, or they may indicate a serious safety threat to people.
Defects that seem insignificant at first glance, if not corrected in a timely manner, can progress and, ultimately, cause complete destruction of structures. Such defects include cracks in stone and concrete structures.
According to the type of development, cracks can be stabilized or unstabilized over time. In order to determine whether the development of a crack continues or has stopped, a beacon is installed on it at the place of greatest development of the crack. When observing the development of a crack along its length, the ends of the crack are fixed with transverse strokes during each inspection. The date of inspection is indicated next to each stroke. The location of the cracks is schematically plotted on the drawing of the walls of the building or structure, noting the numbers and date of installation of the beacons. For each crack, a schedule of its development and opening is drawn up. Based on the results of systematic inspections, a report is drawn up, which indicates the date of inspection, a drawing with the location of cracks and beacons, information about the absence or appearance of new cracks. The rupture of the beacon or the displacement of the plates relative to each other indicates the development of deformations. Beacons are inspected a week after their installation, then at least once a month. In case of intense cracking, daily monitoring is required. The opening width of cracks during observations is measured using crack gauges. The observation log records the number and date of installation of the beacon, the location and layout, the initial width of the crack, and changes in the length and depth of the crack over time. If the beacon is deformed, a new one is installed next to it, which is assigned the same number, but with an index. Lighthouses on which cracks have appeared are not removed until the end of observations. If no change in the size of the cracks is detected within 30 days, their development can be considered complete, the beacons can be removed and the cracks can be repaired.
Gypsum (cement) beacons
Of all the methods, the traditional design of a gypsum or cement beacon for observing cracks has the least cost. Dimensions of beacons: length 250-300 mm, width 70-100 mm, thickness 20-30 mm. Beacons are installed across cracks in places of their greatest development and are securely fixed to the load-bearing part of the walls on both sides of the crack (see Fig. 1).
Beacons are placed in places cleared of plaster, allowing for daily observations. Each beacon is assigned a number and the date of its installation is indicated. It is not allowed to install gypsum beacons in damp places - in this case it is necessary to install beacons made of cement mortar.
Plate beacons
The design of the beacons allows their use in a wide range of weather, temperature and humidity conditions. Readings can be taken both visually and using measuring instruments.
The deformation scale consists of 2 plastic plates, one of which has a millimeter grid and a reading scale, and the second has a control crosshair.
The strain scale method is the simplest solution for observing cracks that can form as a result of the following phenomena:
Uneven foundation settlement;
- temperature deformations of long walls;
- overloading of individual sections of walls as a result of dismantling the structure without complying with technical requirements.
The deformation scale consists of two plastic plates. They are attached to both sides of the crack so that when the crack opens, the plates slide over one another, and the red crosshair of one plate moves relative to the millimeter scale of the other plate, allowing you to take a report on the scale and enter it in the observation log. The plates must be secured parallel to each other. After attaching the deformation scale to the building, it is assigned a number and the number and date of installation are noted on the scale. By measuring the distance between the scale marks, the size of the crack opening is determined.
Visual monitoring is possible both along the vertical and horizontal axes.
Observation of cracks at 3 – 4 points
In some cases, plate and electronic beacons cannot be used when monitoring cracks. For example, in cases where the risk of damage to beacons is high, or the installation of beacons is undesirable for aesthetic reasons. In these cases, monitoring of cracks in building structures can be carried out using fixed observation points. On each side of the crack, two points are secured using dowels or other devices. The installed devices are usually unnoticeable and at the same time securely fixed. With this method of monitoring cracks, measurements are made using high-precision measuring instruments - digital calipers. The distances between fixed points are measured, and the measurement results are entered into spreadsheets. After processing the data, we obtain the amount of movement of parts of the structure separated by a crack relative to each other along two axes - vertical and horizontal. This method of monitoring the deformations of buildings and structures does not have the capabilities of visual observation, and calculations are required to obtain results.
However, three- or four-point observation is the only reliable and at the same time highly accurate method of observation in places where there is a high probability of losing other types of beacons due to vandals.
In the process of monitoring cracks in load-bearing structures of buildings, the question arises of how best to record the observation results. After all, to control the development of deformations in structures, it is not enough to simply install beacons to monitor cracks. It is also necessary to periodically take readings from these beacons, i.e. measure the width of the crack opening and its other characteristics. These readings must be recorded in documents so that you can always view the history of changes and analyze the monitoring results.
Mandatory forms of documents currently do not exist, but there are recommended ones, which were developed in the development of norms and rules for the operation of buildings, and are also given in recommendations for the inspection of buildings. Let us dwell on the two main forms of documents filled out when monitoring load-bearing structures using beacons.
Crack Surveillance Log
The form of the log for monitoring cracks in building structures is proposed in the Manual for Assessing the Physical Wear of Residential Buildings, developed as a follow-up to VSN 57-88 ( Regulations on technical inspection of residential buildings). In this form of the log, the results of installation and monitoring of cracks using beacons are continuously recorded. The journal form can be downloaded from our website.
Crack Observation Graphic Template
A graphic template for monitoring cracks in load-bearing walls of buildings using beacons is intended to record the results of observations in the form of a visual diagram showing the nature of the measurements taking place. This template is developed based on building inspection guidelines and provides a convenient visual representation of building deformation processes. This form of observation can be used in addition to the log to analyze monitoring results. After downloading, you need to print one template for each observation location (beacon installation). You can download the graphic template form on our website.
The proposed forms for documenting the results of monitoring the development of cracks in buildings can be used both during technical operation and during inspection of buildings. Typically, building maintenance specialists install beacons during spring and fall building inspections when new cracks are identified. Further monitoring of the installed beacons and filling out documents is carried out depending on the accepted frequency, the nature of the deformations and the characteristics of the object.