While observing cracks in load-bearing structures 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 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
Graphical template for monitoring cracks in load-bearing walls 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 in the process technical operation, and when inspecting 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.
Cracks that appear on the walls of a building not only spoil the aesthetics of the building, but are also a sign serious problems architectural plan.
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 lighthouses. Monitoring is also used in buildings identified as emergency or with limited functionality. They monitor the development of the resulting destruction in structures near which active construction works or reconstruction is underway.
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 correct assessment technical condition the buildings;
- decisions on the possibility of further operation;
- necessity and complexity of carrying out 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 one obtains accurate results damage to walls or partitions.
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
Are considered the most in an accessible way monitoring the resulting destruction. Before installation, the damaged surface will need to be leveled. If the structure continues to deform, cracks will form in the lighthouse. In this case, control marks are installed nearby.
This takes into account:
- negative reaction of gypsum to the influence 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 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.
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 building walls, 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
First, let's quote from regulatory documents, where definitions of beacons and gap gauges are given. The first document is an updated GOST, the requirements of which apply to monitoring deformations of the foundations of buildings and structures.
GOST 24846-2012 Soils. Methods for measuring deformations of the foundations of buildings and structures:
3 Terms and definitions
3.34 beacon, crack gauge: A device for monitoring the development of cracks: gypsum or alabaster tiles attached to both edges of the crack on the wall; two glass or plexiglass plates with marks for measuring the size of the crack opening, etc.
10 Observation of cracks
10.1 Systematic observation of the development of cracks should be carried out when they appear in the load-bearing structures of buildings and structures in order to determine the nature of the deformations and the degree of their danger for the further operation of the facility.
10.2 When observing the development of a crack along its length, its ends should be periodically recorded with transverse strokes applied with paint, next to which the date of inspection should be indicated.
10.3 When observing the opening of cracks along the width, you should use measuring or fixing devices attached to both sides of the crack: beacons, crack gauges, next to which their numbers and installation date are indicated.
10.4 If the crack width is more than 1 mm, its depth must be measured.
Appendix A
(required)
A.1 The program for monitoring deformation of the foundations of buildings and structures should cover:
- for buildings (structures) in use - period of operation, results of inspection of the facility, presence of cracks and places to lay beacons (crack gauges);
The second document is the new STO used at Rosatom facilities.
SRO NP "SOYUZATOMSTROY"
STO SRO-S 60542960 00043-2015 “Geodetic monitoring of buildings and structures during construction and operation”
3 Terms and definitions
…
3.21 lighthouse: A signaling device installed on a crack/seam/joint so that changes in crack parameters (opening, closing, shear, elongation, etc.) can be determined visually - without using additional tools and devices.
3.22 crack beacon: A device for observing (monitoring) cracks/seams/joints, combining a signal function for visually identifying the fact of changes in the parameters of cracks/seams/joints with the function of measuring the magnitude of these changes.
…
3.50 gap gauge: A device used to perform, when monitoring the condition of structures, measurements of changes in the parameters of cracks/seams/joints.
Beacon ZI-2.2 according to the classification of STO SRO-S 60542960 00043-2015 is a gap-measuring beacon
An observation beacon or gap gauge is a special device or device designed to monitor changes in the state of defects and damage in the building structures of buildings and structures. When observing cracks, they are used either to identify the fact of a change in the crack opening width, or to determine the magnitude and direction (crack opening/closing) of a change in the crack opening width. Also, in some beacon models, it may be possible to observe the shift along a crack or from the plane of the observed building structures.
Beacon for measurements on two axes
To monitor cracks, beacons are installed directly at the location of the crack for the period necessary to carry out observations. To monitor structural deformations, readings from installed beacons must be periodically taken and recorded in an observation log. The process of constant observation of structures is called monitoring. Specific monitoring periods are established depending on design features building, observation purposes, location and other parameters of the crack. In the vast majority of cases, the beacon must remain on the crack until the causes of the crack have been completely eliminated and repair work to restore/strengthen structures damaged by the crack is completed. Sometimes, beacons can remain on structures after completion of work, to monitor the effectiveness of the repair work carried out. Also, with the help of beacons, changes in the position of building structures of buildings and structures can be observed throughout the entire period of their operation in order to monitor the technical condition.
Types and designs of lighthouses
The simplest beacons are a strip of plaster applied to the structure at the location of the crack. Such a beacon serves to identify the fact of changes in the width of the crack opening and cannot help in determining the quantitative values of these changes. Gypsum and cement beacons have a number of requirements and restrictions on use. what you need to know when installing them. Glass beacons can be made similarly to plaster ones - a strip of glass across the crack, or provide for the possibility of taking measurements in the case where two glass plates are installed on both sides of the crack. Such beacons are the most common due to their low price and ease of installation. However, their use is ineffective due to low accuracy and other problems associated with the design of these beacons. Additional information about glass and other types of lighthouses can be found in the article describing methods for monitoring deformations in building structures. It should be noted that paper and other similar materials cannot be used to observe cracks for a number of objective reasons, which can be read about in the corresponding article “The myth about the existence of “paper beacons”.
Mechanical beacon
Electronic monitoring device
There are also so-called “mechanical” beacons. These are devices of various designs, the task of which is to measure the magnitude of changes in crack opening. There are a lot of lighthouse designs of this type. Basically, these are some elements installed on both sides of the crack, with a scale and indicator that allow you to see the change in the size of the crack opening without additional devices. The most accurate of mechanical devices is a beacon made on the basis of a dial indicator. Expanding the functionality and accuracy of “mechanical” type beacons is possible when using modern high-precision devices for measurements. measuring instruments, such as electronic calipers. The design of professional observation beacons always includes special reference points, which are used for high-precision measurements.
Monitoring system
The most modern beacons are made using electronic components, such as strain gauges, or using optical technologies. They also have different design and opportunities. In addition to directly measuring the crack opening, they can collect information about temperature and humidity conditions and other parameters. It is possible to equip them with modules for remote information transfer for monitoring the condition of structures in real time. The problems with their use are mainly related to at a high price and the difficulties of preventing unauthorized access to them by unauthorized persons. Some
The main causes of cracks in building structures: types and features.
To monitor the condition of buildings, special devices are used, which are usually called “beacons”. They are used to monitor the deformation of an object, to monitor emergency structures, and when operating near construction or restoration work, which may affect the integrity of the building.
Installing beacons on cracks makes it possible to accurately record all changes occurring, and thanks to this, monitor the objective condition of the building. Based on the results of measurements, a decision is made as to whether the building can continue to be used, or whether it requires repairs, or the elimination of factors causing the crack to increase (for example, stopping nearby construction).
The choice of beacons for monitoring cracks is carried out depending on the condition of the object and the features of a particular structure, as well as taking into account the following issues:
- How precise changes are required?
- Is it important to measure the effects of temperature and humidity?
- Will it be convenient to service the device and take readings?
- The price and service life of the device, where it will be installed, is it possible to ensure its safety?
Depending on these issues, the optimal type of monitoring system is selected.
Types of beacons for cracks in the wall:
We will consider 5 main options for monitoring systems, which differ in price, capabilities and installation features. It is impossible to clearly name the best of them, since each has its own advantages and is used in different situations.
Gypsum beacons for cracks
This is the most traditional way, and at the same time the cheapest, since it is disposable. As soon as it works, that is, a crack or break appears in its body, it is necessary to install a new one nearby. At the same time, the reliability of the indicators is quite low, and usually at least two pieces are installed, at the rate of one piece for every three meters of the fault. It is important to understand that this method of crack control has whole line disadvantages:
- Not suitable for outdoor use due to temperature changes and exposure external factors Arbitrary destruction of the sensor is possible.
- Installation is not carried out at sub-zero temperatures.
- Performance largely depends on the quality of installation and proper preparation of the surface, taking into account the size and design features of the sensor.
- The measurement accuracy is not very high, since when triggered the system quickly collapses.
Electronic beacons for cracks
The optimal choice if you need to calculate how a crack is affected by changes in temperature and humidity from inside and outside the building. Electronic measuring sensors today can transmit information remotely, recording differences of tenths and hundredths of a millimeter.
Electronic beacons for cracks on walls have their own characteristics:
- It is impossible to measure how much parts of the structure have moved up and to the sides if only one sensor is installed.
- The cost of the equipment is quite high, and resistance to vandalism is low, so it is problematic to install them in public places.
- More often this method used for short-term measurements, ranging from several days to two weeks, in order to quickly monitor the situation and make a decision.
Plate beacon for monitoring cracks
This is very simple design, to some extent reminiscent of gypsum, but without the inherent disadvantages of the latter. To date this type They are used most widely, since it is optimal in terms of installation cost, ease of observation and accuracy of the results obtained.
Installing a beacon on a crack is very simple; it requires dowels or epoxy glue (sometimes both are used), and any marks can be applied to the surface to facilitate monitoring. This diagnostic method compares favorably with others:
- Thanks to the use of a signal measuring scale, changes in the opening are monitored visually, without the use of any tools, but they can also be used to measure the opening width even by hundredths of a millimeter.
- It is easy to track the movement of the structure along two or even three axes.
Point beacons on cracks in buildings
These are inconspicuous, but very durable sensors that are highly resistant to vandalism, as they are properly attached to the wall. There are a variety of fastening methods, ranging from the simplest dowels to special mounting devices - it all depends on the specific object. Peculiarities:
- You can monitor measurements at 2, 3 or 4 points, and track how much parts of the building have moved upward or horizontally relative to each other.
- You can make beacons for cracks almost invisible, from organic glass or material to match the coating, and in many cases it is not even necessary preliminary preparation surfaces or removal of finishes.
- To measure the opening are used various instruments, and the accuracy of the indicators depends solely on the accuracy of the estimator.
Monitoring cracks using sentinel beacons
These systems, also called “messuras,” do not require special measuring instruments; they already have their own scale with high-precision sensors. Most convenient option to track the slightest changes and quickly record readings. Features of application:
- Such beacons for monitoring cracks are quite expensive, and can only be comparable in price to electronic ones. At the same time, they attract vandals as much as possible, and even special protective structures cannot save them. They are placed inside buildings or outside, but in such a way as to ensure the possibility of monitoring an expensive device.
- As an option, the method of fixing two points on the fault is used, and the messuras are used only as measuring device to evaluate how much the space between them has changed.
We considered only the 5 most popular options. There are also paper and glass systems, but they have a lot of disadvantages, and in this case, installing beacons on cracks will not provide the required measurement accuracy. It is better to choose one of the sensors described above.
Rules for installing beacons on cracks
The state regulates certain norms and standards for sensors different types, as well as the frequency of readings. Before installing beacons on a crack in the wall, it is necessary to study these requirements and be guided by them during the installation and monitoring process.
If during the monitoring process (usually 30 days) the system does not work, it is concluded that the deformation has ended, and the resulting crack is usually simply covered with mortar. If the lighthouse is deformed (the first 20-30 days after fastening are especially important), it means that the destruction continues, and a decision must be made on further operation or repair of the object.
- The initial installation of beacons on walls with cracks is always carried out in the place of greatest discrepancy.
- Each sensor is assigned a number, and the installation date is indicated in the log.
- With active deformation, the beacon is inspected once every 48 hours or more often; with slow deformation, checking once a week or even less is acceptable.
- If the system has worked and is deformed, a new beacon is placed nearby, but the old one is not removed.
- When installing beacons on cracks in walls, the location of installation, its number, the date of work, as well as the initial width of the fault are recorded in the log.
- It is important to monitor not only how much the crack opens, but also whether it lengthens. If elongation occurs, a new sensor is placed on that end.
- Installation of beacons on cracks in brick walls permitted only after proper cleaning of the surface from dust and dirt. It is recommended to flush the fracture clean water, measure its depth, and only then install the sensor. Cracks are sealed with cement or metal staples.
- The wall can be deformed not only due to problems with the masonry, but also due to temperature effects, so after installing the system, it is necessary to check whether the sensor is moving away and whether its functionality has been impaired.
Maxim Fedin
Melwood company expert
Spent 255 construction expertise, 4 forensic examinations
In company with 2017 of the year