GOST 22690 updated. Determination of strength by mechanical methods of non-destructive testing
The compressive strength of concrete is the main indicator that characterizes concrete.
There are two systems for expressing this indicator:
The compressive strength of concrete is the main indicator that characterizes concrete. It is on him that the non-destructive testing of concrete strength in monolithic structures... There are two systems for expressing this indicator:
- Concrete class, B is the so-called cube strength (i.e. a compressible cube-shaped specimen), indicating the withstanding pressure in MPa. The fraction of the probability of failure during the strength test of concrete does not exceed 5 units out of 100 tested samples. It is designated by the Latin letter B and a number indicating strength in MPa. According to SNiP 2.03.01–84 "Concrete and reinforced concrete structures".
- Concrete grade, M is the ultimate compressive strength of concrete, kgf / cm². It is designated by the Latin letter M and numbers from 50 to 1000. The maximum deviation that allows the control and assessment of concrete strength in accordance with GOST 26633-91 “Heavy and fine-grained concrete is 13.5%.
The concrete grade and class are determined after 28 days from the day of pouring, under normal conditions, or the calculation is carried out taking into account the coefficient (after 7-14 days the material acquires 60-80% of the brand strength, after 28 days about 100%, after 90 days -130% .). Ultrasonic method non-destructive testing concrete is carried out, as a rule, at the intermediate and design age of the reinforced concrete structure.
The strength of concrete is influenced by a number of factors: the activity of the cement, the content of cement, the ratio of water to cement by weight, the quality of aggregates, the quality of mixing and the degree of compaction, the age and conditions of concrete hardening, repeated vibration. The speed of concrete hardening is greatly influenced by the temperature and humidity of the environment. An environment with a temperature of 15–20 ° C and an air humidity of 90–100% is considered conditionally normal. With an increase in the content of cement in concrete, its strength increases to a certain limit. Then it grows slightly, while other properties of concrete deteriorate: shrinkage and creep increase. Therefore, it is not recommended to add more than 600 kg of cement per 1 m³ of concrete.
Conformity of concrete grade (M) to class (B) and compressive strength
|
Concrete grade, M |
Concrete class, B |
Strength, MPa |
Strength, kg / cm 2 |
Chipping-off method occupies a special place among non-destructive methods for determining the strength of concrete. Considering non-destructive method, the method of separation with spalling is in essence a destructive method, since the strength of concrete is estimated by the force required to destroy a small volume of concrete, which makes it possible to most accurately estimate its actual strength. Therefore, this method is used not only to determine the strength of concrete of unknown composition, but can also serve to construct calibration dependences for other non-destructive testing methods. This method is applied to heavy concretes and structural concretes on light aggregates in monolithic and prefabricated concrete and reinforced concrete products, structures and structures and establishes a method for testing concrete and determining its compressive strength by local destruction of concrete when a special anchor device is pulled out of it. Such ultrasonic method for testing concrete strength allows you to determine the compressive strength for concrete in the strength range from 5.0 to 100.0 MPa. When developing the standard, materials from GOST 22690–88 were used.
One of the most common and effective ways non-destructive testing of concrete strength determination is a measurement with a sclerometer, or as it is also called, Schmidt's hammer.
Methods for determining the strength of concrete: equipment used
The devices below can be used to carry out non-destructive testing of concrete. This allows you to more accurately predict physical characteristics ready reinforced concrete structures, which means - to minimize losses construction organization and to protect the customer of the work from all kinds of troubles.
Among other things, such quality control of concrete allows for inspections of concrete, the temperature of which has dropped below 0 ° C. Traditional methods quality control of concrete in laboratory conditions cannot boast of such convenience: previously it was necessary to take a sample and check it at room temperature in the laboratory. Interesting modern solution also by the fact that contractors may not use the services of specialized organizations at every stage construction works... In turn, specialists can independently come to the site and conduct an examination of the quality of concrete in accordance with GOST standards. The equipment is quite compact and mobile, and the preparation of results takes a minimum of time.
Equipment used
Schmidt hammer Original Schmidt type N
Testing of concrete products by means of the Schmidt hammer Original Schmidt is the most widespread measurement technique all over the world that does not destroy concrete in accordance with GOST 22690-2015
For each specific test on concrete products, Proceq offers the appropriate hammer model.
Original Schmidt concrete hammer models are available with different impact energies for testing materials of various types and sizes.
Our hammers types N, NR, L and LR are specially designed to evaluate the quality and compressive strength of concrete products ranging from 10 to 70 N / mm2 (1,450 to 10,152 psi).
Models with built-in paper recorders (LR and NR) are capable of automatically recording rebound values on paper tape.
Type Approval Certificate SI Brochure Schmidt Hammers
POS-50MG4 "Skol" is intended for non-destructive testing of concrete strength by spalling ribs, tearing off and spalling and tearing off steel discs in accordance with GOST 22690-2015.
Measuring the strength of concrete using such equipment is allowed both on projects under construction and on finished buildings. The device is indispensable in the construction industry, in the work of utilities and restoration bureaus, who periodically check the integrity of buildings. The model received a non-volatile memory, in which the last two hundred measurement results are stored. They are marked with the concrete grade and the exact date of the analysis, allowing specialists to easily track the dynamics of changes in key indicators.
Excerpts from GOST 22690 DETERMINATION OF STRENGTH BY MECHANICAL METHODS OF NON-DESTRUCTIVE CONTROL
TESTING
4.1. The tests are carried out on a construction site with an area of 100 to 600 cm 2.
4.2. The strength of concrete in the controlled section of the structure is determined by calibration dependence established in accordance with the requirements of Sec. 3, provided that the measured values of the proxy are between the lowest and highest values an indirect indicator in the samples tested in the construction of the calibration dependence.
4.3. The number and location of controlled areas during testing of structures must comply with the requirements of GOST 18105-86 or be specified in the standards and (or) technical conditions on prefabricated or in working drawings for monolithic structures and (or) in technological maps for control. When determining the strength of the examined structures, the number and location of the sections should be taken according to the survey program.
4.4. The number of tests in one section, the distance between the test sites at the site and from the edge of the structure, the thickness of the structure at the test site must be not less than the values given in table. 3.
Table 3 mm
4.5. The roughness of the surface of the concrete section of the structure when tested by the methods of rebound, shock impulse, plastic deformation must correspond to the roughness of the surface of the cubes tested when establishing the calibration dependence. If necessary, cleaning the surface of the structure is allowed. When testing by plastic deformation at indentation, if the zero reading is removed after applying the initial load, there are no requirements for the roughness of the concrete surface of the structures.
4.6. Method elastic rebound
4.6.1. When testing by the method of elastic rebound, the distance from the test sites to the reinforcement should be at least 50 mm.
4.6.2. The test is carried out in the following sequence: the device is positioned so that the force is applied perpendicular to the test surface in accordance with the instructions for use of the device; it is recommended that the position of the device during the test of the structure relative to the horizontal be taken the same as when testing the samples to establish the calibration dependence; in a different position, it is necessary to correct for the readings in accordance with the instructions for use of the device; fix the value of the indirect characteristic in accordance with the instruction manual of the device; calculate the average value of the indirect characteristic at the site of the structure.
4.7. Plastic deformation method.
4.7.1. When testing by the method of plastic deformation, the distance from the test sites to the reinforcement should be at least 50 mm.
4.7.2. The test is carried out in the following sequence: the device is positioned so that the force is applied perpendicular to the test surface in accordance with the instructions for use of the device; with a spherical indenter, the test is allowed to be carried out to facilitate measurements of the diameters of prints through sheets of carbon and white paper (in this case, the samples for establishing the calibration dependence are tested using the same paper); fix the values of the indirect characteristic in accordance with the instructions for use of the device; calculate the average value of the indirect characteristic at the site of the structure. 4.8. Shock pulse method
4.8.1. When testing by the shock pulse method, the distance of the test points to the reinforcement should be at least 50 mm.
4.8.2. The tests are carried out in the following sequence: the device is positioned so that the force is applied perpendicular to the test surface in accordance with the instructions for use of the device; it is recommended that the position of the device during the test of the structure relative to the horizontal be taken the same as when testing the samples to establish the calibration dependence; in a different position, it is necessary to correct for the readings in accordance with the instructions for use of the device; fix the value of the indirect characteristic in accordance with the instruction manual of the device; calculate the average value of the indirect characteristic at the site of the structure.
4.9. Tear-off method
4.9.1. When tested by the pull-off method, the sections shall be located in the zone of lowest stresses caused by the service load or the compression force of the prestressed reinforcement.
4.9.2. The test is carried out in the following sequence: at the place where the disc is glued, remove the surface layer of concrete with a depth of 0.5 - 1 mm and the surface is cleaned of dust; the disc is glued to the concrete so that the layer of glue on the concrete surface does not go beyond the disc; the device is connected to the disk; the load is gradually increased at a rate of (1 P 0.3) kN / s; fix the readings of the force meter of the device; measure the projection area of the separation surface on the plane of the disk with an error of P0.5 cm 2; determine the value of the conditional stress in concrete at separation. The test results are not taken into account if reinforcement was found during concrete tearing or the projected area of the tearing surface was less than 80% of the disc area.
4.10. Pull-off method with spalling 4.10.1. In the shear pull test, the sections shall be located in the zone of lowest stresses caused by the service load or the compression force of the prestressed reinforcement.
4.10.2. The tests are carried out in the following sequence: if the anchor device was not installed before concreting, then a hole is drilled or punched in the concrete, the size of which is selected in accordance with the instructions for use of the device, depending on the type of anchor device; an anchor device is fixed in the borehole to a depth specified in the instruction manual for the device, depending on the type of anchor device; the device is connected to the anchor device; the load is increased at a speed of 1.5 - 3.0 kN / s; record the reading of the force meter of the device and the depth of the cutout with an accuracy of at least 1 mm. If the largest and smallest size of the torn-out part of the concrete from the anchor device to the boundaries of destruction along the surface of the structure differ by more than two times, and if the tear-out depth differs from the embedment depth of the anchor devices by more than 5%, then the test results may be taken into account only for an approximate assessment of the strength of concrete.
4.11. Rib cleaving method
4.11.1. When testing the rib shear method, there should be no cracks, concrete gaps, sagging or cavities with a height (depth) of more than 5 mm in the test area. The sections should be located in the zone of the lowest stresses caused by the operational load or the compression force of the prestressed reinforcement.
4.11.2. The test is carried out in the following sequence: the device is fixed to the structure, the load is applied at a speed not exceeding (1 P 0.3) kN / s; fix the readings of the force meter of the device; measure the actual shearing depth; determine the average value of the shearing force. The test results are not taken into account if the reinforcement was exposed during spalling of concrete and the actual spalling depth differed from the specified one (see Appendix 3) by more than 2 mm.
V.A.Klevtsov, Dr. Sciences (topic leader); M.G. Korevitskaya, Cand. tech. sciences; YK Matveev; V.N. Artamonov; N.S.Vostrova; A.A. Grebenik; G.V. Sizov, Cand. tech. sciences; D.A. Korshunov, Cand. tech. sciences; M.V. Sidorenko, Cand. tech. sciences; Yu.I. Kurash, Cand. tech. sciences; A.M. Leshchinsky, Cand. tech. sciences; V.R. Abramovsky; V. A. Dorf, Cand. tech. sciences; E.G. Sorkin, Cand. tech. sciences; V.L. Chernyakhovsky, Cand. tech. sciences; I.O. Krol, Cand. tech. sciences; S.Ya. Khomutchenko; Ya.E. Ganin; O.Yu.Sammal, Cand. tech. sciences; A.A. Rulkov, Cand. tech. sciences; P.L. Thalberg; A.I. Markov, Cand. tech. sciences; R.O. Krasnovsky, Cand. tech. sciences; L.S. Pavlov, Cand. tech. sciences; M.Yu. Leshchinsky, Cand. tech. sciences; G.A. Tselykovsky; I.E. Shkolnik, Cand. tech. sciences; T.Yu. Lapenis, G.I. Weingarten, Cand. tech. sciences; N.B. Zhukovskaya; S.P. Abramova; I.N. Nagornyak
This International Standard applies to heavy and lightweight concrete and specifies methods for determining the compressive strength of structures by rebound, shock impulse, plastic deformation, shear, rib shear and shear-chipping.
The dimensions of the indentation on concrete (diameter, depth, etc.) or the ratio of the diameters of the indentations on the concrete and the standard specimen when the indenter is hit or the indenter is pressed into the concrete surface;
The value of the stress required for local destruction of concrete when tearing off a metal disk glued to it, equal to the pull-off force divided by the projection area of the concrete tear-off surface onto the plane of the disc;
1.3. Mechanical methods of non-destructive testing are used to determine the strength of concrete of all types of rated strength, controlled in accordance with GOST 18105, as well as to determine the strength of concrete during inspection and rejection of structures.
1.4. The tests are carried out at a positive concrete temperature. It is allowed to determine the strength when examining structures negative temperature, but not less than minus 10 ° C, provided that by the time of freezing the structure has been kept for at least one week at a positive temperature and a relative humidity of no more than 75%.
1.5. The assessment of the conformity of the values of the actual concrete strength obtained using the methods given in this standard to the established requirements is carried out in accordance with GOST 18105.
2.1. The strength of concrete is determined using instruments designed to determine indirect characteristics that have passed metrological certification in accordance with GOST 8.326 * and meet the requirements given in Table 2.
| The name of the characteristics of the devices | Characteristics of instruments for the method | |||||
| elastic rebound | shock impulse | plastic deformation | detachment | chipping ribs | shearing off | |
| Striker, striker or indenter hardness HRCэ, not less | ||||||
| Roughness of the contact part of the striker or indenter, μm, no more | ||||||
| Diameter of striker or indenter, mm, not less | ||||||
| The thickness of the edges of the disk indenter, mm, not less | 10 | |||||
| Conical indenter angle | 30-60 ° | |||||
| Indentation diameter,% of the indenter diameter | 20-70 | |||||
| Squareness tolerance when a load is applied at a height of 100 mm, mm |
||||||
| Impact energy, J, not less | 0,02 | |||||
| Load increase rate, kN / s | 1,5* | 0,5-1,5 | 0,5-1,5 | 1,5-3,0 | ||
| Load measurement error from measured load,%, no more | 5* | |||||
2.2. A tool for measuring the diameter or depth of indentations (angular scale in accordance with GOST 427, a caliper in accordance with GOST 166, etc.) used for the method of plastic deformation should provide measurements with an error of no more than ± 0.1 mm, and the instrument for measuring the depth of an indentation (indicator watch type according to GOST 577, etc.) - with an error of no more than ± 0.01 mm.
It is also allowed to use other anchoring devices, the embedment depth of which must not be less than the maximum size of the coarse concrete aggregate of the test structure.
2.5. For the tear-off method, steel discs with a diameter of at least 40 mm, a thickness of at least 6 mm and at least 0.1 of a diameter, with a roughness parameter of the glued surface of at least 20 microns in accordance with GOST 2789 should be used.
3.1. To determine the strength of concrete in structures, a calibration relationship is preliminarily established between the strength of concrete and an indirect characteristic of strength (in the form of a graph, table or formula).
For the method of separation with shearing, in the case of using anchor devices in accordance with Appendix 2, and for the method of shearing of the rib, in the case of using devices in accordance with Appendix 3, it is allowed to use the calibration dependencies given in Appendices 5 and 6, respectively.
INTERSTATE COUNCIL FOR STANDARDIZATION, METROLOGY AND CERTIFICATION
INTERSTATE COUNCIL FOR STANDARDIZATION, METROLOGY AND CERTIFICATION
INTERSTATE
STANDARD
CONCRETE
Determination of strength by mechanical methods of non-destructive testing
(EN 12504-2: 2001, NEQ)
(EN 12504-3: 2005, NEQ)
Official edition
Rinform stand 2016
Foreword
The goals, basic principles and basic procedure for carrying out work on the interstate standardization are established by GOST 1.0-92 “Interstate standardization system. Basic Provisions "and GOST 1.2-2009" Interstate Standardization System. Interstate standards. rules and recommendations for interstate standardization. Rules for development, acceptance, application, updating and cancellation "
Information about the standard
1 DEVELOPED by the Research and Development Department of Construction Research Center JSC. Design and Technological Institute of Concrete and Reinforced Concrete named after A.A. Gvozdeva (NIIZHB)
2 INTRODUCED by the Technical Committee for Standardization TC 465 "Construction"
3 ACCEPTED by the Interstate Council for Standardization, Metrology and Certification (Minutes dated June 18, 2015 No. 47)
4 By Order Federal agency on technical regulation and metrology dated September 25, 2015 No. 1378-st, the interstate standard GOST 22690-2015 was put into effect as a national standard Russian Federation from April 1, 2016
5 8 this standard takes into account the main regulations regarding the requirements for mechanical methods of non-destructive testing of concrete strength of the following European regional standards:
EN 12504-2: 2001 Testing concrete in structures - Part 2: Non-destructive testing - Determination of rebound number.
EN 12504-3: 2005 Testing concrete in structures - Determination of pull-out force.
Degree of Compliance - Non-Equivalent (NEQ)
6 83AMEN GOST 22690-88
Information about changes to this standard is published in the annual information index "National Standards", and the text of changes and amendments is published in the monthly information index "National Standards". In case of revision (replacement) or cancellation of this standard, a corresponding notice will be published in the monthly information index * National standards. " Relevant information, notice and texts are also posted in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet
© Standartinform. 2016
In the Russian Federation, this standard may not be reproduced in whole or in part. replicated and distributed as an official publication without the permission of the Federal Agency for Technical Regulation and Metrology
Annex A (normative) Standard test set-up for the shear peel test. ... ... ten
INTERSTATE STANDARD
Determination of strength by mechanical methods of non-destructive testing
Determination of strength by mechanical methods of nondestructive testing
Date of introduction - 2016-04-01
1 area of use
This standard applies to structural heavy, fine-grained, lightweight and prestressing concrete of monolithic, precast and precast-monolithic concrete and reinforced concrete products... structures and structures (hereinafter referred to as structures) and establishes mechanical methods for determining the compressive strength of concrete in structures by elastic rebound, shock impulse, plastic deformation, separation, rib shearing and separation by shearing.
8 of this standard, normative references to the following interstate standards are used:
GOST 166-89 (ISO 3599-76) Calipers. Technical conditions
GOST 577-68 Hour-type indicators with a separation price of 0.01 mm. Technical conditions
GOST 2789-73 Surface roughness. Parameters and characteristics
GOST 10180-2012 Concrete. Methods for determining the strength of control samples
GOST 18105-2010 Concrete. Rules for the control and assessment of strength
GOST 28243-96 Pyrometers. General technical requirements
GOST 28570-90 Concrete. Methods for determining strength by samples taken from structures
GOST 31914-2012 High-strength heavy and fine-grained concretes for monolithic structures. Quality control and assessment rules
Note - When using this standard, it is advisable to check the operation of the reference standards in the public information system - not the official website of the Federal Agency for Technical Regulation and Metrology on the Internet or according to the annual information index "National Standards", which was published as of January 1 of the current year, and on the issues of the monthly information index "National Standards" for the current year. If the reference standard is replaced (changed), then when using this standard, the replacing (modified) standard should be followed. If the reference standard is canceled without replacement, then the provision in which the reference to it is given applies to the extent that does not affect this reference.
3 Terms and definitions
8 of this standard, the terms according to GOST 18105 are used, as well as the following terms with the corresponding definitions:
Official edition
destructive methods for determining the strength of concrete: Determination of the strength of concrete from control samples made of concrete mix according to GOST 10180 or selected from structures according to GOST 28570.
[GOST 18105-2010. article 3.1.18]
3.2 non-destructive mechanical methods for determining the strength of concrete: Determining the strength of concrete directly in the structure under local mechanical action on concrete (impact, separation, chipping, indentation, separation with shearing, resilient rebound).
3.3 indirect non-destructive methods for determining the strength of concrete: Determination of the strength of concrete according to pre-established calibration dependencies.
3.4 direct (standard) non-destructive methods for determining the strength of concrete: Methods that provide for standard test schemes (separation with shearing and shearing of ribs) and allowing the use of known calibration dependencies without reference and correction
3.5 calibration dependence: Graphic or analytical dependence between the indirect characteristic of strength and the compressive strength of concrete, determined by one of the destructive or direct non-destructive methods.
3.6 indirect strength characteristics (indirect indicator): The magnitude of the applied force during local destruction of concrete, the magnitude of the rebound, the impact energy, the size of the indentation or other indication of the device when measuring the strength of concrete by non-destructive mechanical methods.
4 General
4.1 Non-destructive mechanical methods are used to determine the compressive strength of concrete at the intermediate and design age established by the design documentation and at an age exceeding the design age when examining structures.
4.2 Non-destructive mechanical methods for determining the strength of concrete, established by this standard, are subdivided according to the type of mechanical effect or determined indirect characteristics by the method:
Elastic rebound;
Plastic deformation;
> shock impulse:
Breakaway with shearing:
Rib chipping.
4.3 Non-destructive mechanical methods for determining the strength of concrete are based on the relationship between the strength of concrete and indirect strength characteristics:
The method of elastic rebound based on the relationship between the strength of concrete and the rebound value of the striker from the concrete surface (or the striker pressed against it);
The method of plastic deformation on the relationship between the strength of concrete and the dimensions of the indentation on the concrete of the structure (diameter, depth, etc.) or the ratio of the diameter of the indentation on concrete and the standard metal sample when the indenter hits or the indenter is pressed into the concrete surface;
Impact impulse method based on the relationship between the strength of concrete and the impact energy and its changes at the moment the striker collides with the concrete surface;
The method of separation on the bond of the stress required for local destruction of concrete when tearing off a metal disk glued to it, equal to the separation force divided by the area of the projection of the surface of concrete separation on the plane of the disk;
The method of separation with chipping on the connection between the strength of concrete and the value of the force of local destruction of concrete when the anchor device is excavated from it;
The method of chipping a rib on the connection between the strength of concrete and the value of the force required to chip a section of concrete on the rib of the structure.
4.4 In general, non-destructive mechanical methods for determining the strength of concrete are indirect non-destructive methods for determining the strength. The strength of concrete in structures is determined by the experimentally established calibration dependencies.
4.5 The method of shearing and spalling when tested in accordance with the standard scheme of annex A and the method of chipping a rib when testing in accordance with the standard scheme of annex B are direct non-destructive methods for determining the strength of concrete. For direct non-destructive methods, it is allowed to use the calibration dependencies established in Appendices b and D.
Note - Standard test schemes are applicable in a limited range of concrete strength (see Appendices A and B) For cases not related to standard test schemes, grout dependencies should be established according to general rules.
4.6 The test method should be selected taking into account the data given in Table 1 and additional restrictions established by the manufacturers of specific measuring instruments. The use of methods outside the ranges of concrete strength recommended in Table 1 is allowed with a scientific and technical justification based on the results of research using measuring instruments that have passed metrological certification for an extended range of concrete strength.
Table 1
4.7 The determination of the strength of heavy concrete of design classes B60 and above or with an average compressive strength of concrete R m i 70 MPa in monolithic structures must be carried out taking into account the provisions of GOST 31914.
4.8 The strength of concrete is determined in areas of structures that do not have visible damage (peeling of the protective layer, cracks, cavities, etc.).
4.9 The age of the concrete of the controlled structures and its sections should not differ from the age of the concrete of the structures (sections, samples) tested to establish the calibration dependence by more than 25%. Exceptions are strength control and construction of a calibration dependence for concrete that is more than two months old. In this case, the age difference individual designs(sites, samples) is not regulated.
4.10 The tests are carried out at a positive concrete temperature. It is allowed to carry out tests at a negative concrete temperature, but not lower than minus 10 "C, when establishing or linking a calibration dependence, taking into account the requirements of 6.2.4. The concrete temperature during testing must correspond to the temperature provided for by the operating conditions of the devices.
Calibration dependencies established at a concrete temperature below 0 * C are not allowed to be used at positive temperatures.
4.11 If it is necessary to test concrete of structures after heat treatment at a surface temperature of T to 40 * C (to control the tempering, transfer and stripping strength of concrete), the calibration dependence is established after determining the strength of concrete in the structure by an indirect non-destructive method at a temperature (i (T ± 10) * С, and concrete testing by direct non-destructive method or specimen testing - after cooling down at normal temperature.
5 Measuring instruments, apparatus and instrument
5.1 Measuring instruments and instruments for mechanical testing, designed to determine the strength of concrete, must be certified and verified in established order and must meet the requirements of Appendix D.
5.2 Instrument readings, graded in units of concrete strength, should be considered as an indirect indicator of concrete strength. The specified devices should only be used after
establishment of the calibration dependence "meter reading - concrete strength" or linking the dependence established in the device in accordance with 6.1.9.
5.3 A tool for measuring the diameter of indentations (vernier caliper in accordance with GOST 166), used for the method of plastic deformation, must ensure measurement with an error of no more than 0.1 mm. a tool for measuring the depth of an impression (dial indicator according to GOST 577, etc.) - with an error of no more than 0.01 mm.
5.4 Standard test procedures for shear-off and rib-chipping tests provide for the use of anchoring devices and grips in accordance with Appendices A and B.
5.5 For the chipping method, anchoring devices should be used. the embedment depth of which should not be less than the maximum size of the coarse concrete aggregate of the test structure.
5.6 For the tear-off method, steel discs with a diameter of at least 40 mm should be used. with a thickness of at least 6 mm and at least 0.1 of the diameter, with the parameters of the surface roughness of the glued surface not less than Ra = 20 µm in accordance with GOST 2789. The adhesive for gluing the disc must ensure the strength of adhesion to concrete, at which destruction occurs along the concrete.
6 Test preparation
6.1 Procedure for preparation for testing
6.1.1 Preparation for testing includes checking the devices used in accordance with the instructions for their operation and establishing the calibration dependencies between the strength of concrete and the indirect characteristic of strength.
6.1.2 The calibration dependence is established on the basis of the following data:
Results of parallel tests of the same sections of structures using one of the indirect methods and a direct non-destructive method for determining the strength of concrete;
Results of testing sections of structures using one of the indirect non-destructive methods for determining the strength of concrete and testing core samples taken from the same sections of the structure and tested in accordance with GOST 28570:
Results of testing standard concrete samples by one of the indirect non-destructive methods for determining the strength of concrete and mechanical tests in accordance with GOST 10180.
6.1.3 For indirect non-destructive methods for determining the strength of concrete, the calibration dependence is established for each type of rated strength specified in 4.1 for concretes of the same nominal composition.
It is allowed to build one calibration dependence for concretes of the same type with one type of coarse aggregate, with a single production technology, differing in the nominal composition and the value of the rated strength, subject to the requirements of 6.1.7
6.1.4 The permissible difference in the age of concrete of individual structures (sections, samples) when establishing the calibration dependence on the age of concrete of the controlled structure is taken according to 4.9.
6.1.5 For direct non-destructive methods according to 4.5, it is allowed to use the dependencies given in Appendices C and D for all types of normalized concrete strength.
6.1.6 The calibration dependence should have a root-mean-square (residual) deviation S T n m not exceeding 15% of the average concrete strength of the sections or samples used in plotting the dependence, and the correlation coefficient (index) of at least 0.7.
It is recommended to use a linear relationship of the form R * a * bK (where R is the strength of concrete. K is an indirect indicator). The procedure for establishing, evaluating the parameters and determining the conditions for using a linear calibration dependence is given in Appendix E.
6.1.7 When constructing the calibration dependence of the deviation of the unit values of the concrete strength R ^ from the average value of the concrete strength of the sections or samples R f. used to build the calibration dependence, must be within:
> from 0.5 to 1.5 of the average value of concrete strength Rf atYa f £ 20 MPa;
From 0.6 to 1.4 average value of concrete strength R, f at 20 MPa< Я ф £50 МПа;
From 0.7 to 1.3 average value of concrete strength R f at 50 MPa<Я Ф £80 МПа;
From 0.8 to 1.2 of the average value of concrete strength Rf atYa f> 80 MPa.
6.1.8 Correction of the established dependence for concretes at intermediate and design age should be carried out at least once a month, taking into account the additionally obtained test results. The number of samples or sites for additional tests during the adjustment should be at least three. The correction methodology is given in Appendix E.
6.1.9 It is allowed to use indirect non-destructive methods for determining the strength of concrete, using the calibration dependences established for concrete that differs from the tested one in composition, age, hardening conditions, moisture, with reference in accordance with the method of recovery.
6.1.10 Without reference to specific conditions according to Appendix G, the calibration dependences established for concrete that differs from the tested one may only be used to obtain approximate strength values. It is not allowed to use approximate strength values without reference to specific conditions for assessing the strength class of concrete.
6.2 Construction of a calibration dependence based on the results of concrete strength tests
in constructions
6.2.1 When constructing a calibration dependence according to the results of testing the strength of concrete in structures, the dependence is established according to the unit values of the indirect indicator and the strength of concrete of the same sections of structures.
For a unit value of the indirect indicator, the average value of the indirect indicator in the area is taken. For a unit value of concrete strength, the strength of the concrete of the area, determined by direct non-destructive method or by testing of selected samples, is taken.
6.2.2 The minimum number of single values for plotting a calibration dependence based on the results of testing the strength of concrete in structures is 12.
6.2.3 When constructing a calibration dependence based on the results of concrete strength tests in structures that are not subject to testing, or in their zones, measurements are first carried out by an indirect non-destructive method in accordance with the requirements of Section 7.
Then select the sites in the number provided for in 6.2.2, on which the maximum is obtained. minimum and intermediate values of the indirect indicator.
After testing by the indirect non-destructive method, the areas are tested by the direct non-destructive method or samples are taken for testing in accordance with GOST 26570.
6.2.4 To determine the strength at a negative temperature of concrete, the areas selected for the construction or binding of the calibration dependence are first tested by the indirect non-aerial method, and then samples are taken for subsequent testing at a positive temperature or heated. external sources heat (infrared emitters, heat guns and others) to a depth of 50 mm to a temperature not lower than 0 * C and are tested by a direct non-destructive method. Temperature control of the heated concrete is carried out at the depth of installation of the anchor device in the prepared hole or along the surface of the chip in a non-contact way using a pyrometer in accordance with GOST 28243.
The rejection of the test results used to construct the calibration dependence at negative temperatures is allowed only if the deviations are associated with a violation of the test procedure. In this case, the rejected result should be replaced by the results of a repeated test in the same area of the structure.
6.3 Construction of calibration dependence on control samples
6.3.1 When constructing a calibration dependence for control samples, the dependence is established according to the unit values of the indirect indicator and the strength of concrete of standard sample cubes.
For a unit value of the indirect indicator, the average value of the indirect indicators for a series of samples or for one sample (if the calibration dependence is established for individual samples) is taken. For a unit value of concrete strength, the strength of concrete in a series according to GOST 10180 or one sample (calibration dependence for individual samples) is taken. Mechanical tests samples in accordance with GOST 10180 are carried out directly after tests by the indirect non-destructive method.
6.3.2 When constructing a calibration dependence based on the test results of cube samples, at least 15 series of cube samples in accordance with GOST 10180 or at least 30 separate cube samples are used. Samples are made in accordance with the requirements of GOST 10180 in different shifts, for at least 3 days from concrete of the same nominal composition, using the same technology, with the same hardening mode as the structure to be controlled.
The unit values of the concrete strength of the cube specimens used to construct the calibration dependence must correspond to the deviations expected in production, while being within the ranges established in 6.1.7.
6.3.3 The calibration dependence for the methods of elastic rebound, shock pulse, plastic deformation, separation and spalling of the rib is established on the basis of the test results of the manufactured cube specimens, first by the non-destructive method, and then by the destructive method according to GOST 10180.
When establishing the calibration dependence for the method of separation with spalling, make the main and control samples according to 6.3.4. An indirect characteristic is determined on the main samples. control samples are tested in accordance with GOST 10180. Main and control samples must be made of the same concrete and harden under the same conditions.
6.3.4 The dimensions of the samples should be selected in accordance with the largest aggregate size in the concrete mixture in accordance with GOST 10180. but not less than:
100 * 100 * 100 mm for rebound, shock impulse, plastic deformation methods. as well as for the method of separation with chipping (control samples);
200 * 200 * 200 mm for the method of chipping the rib of the structure:
300 * 300 * 300 mm. but with a rib size of at least six depths of installation of the anchor device for the shear-off method (basic samples).
6.3.5 To determine the indirect strength characteristics, tests are carried out in accordance with the requirements of Section 7 on the lateral (in the direction of concreting) faces of the cube specimens.
The total number of measurements on each specimen for the method of elastic rebound, shock pulse, plastic deformation upon impact must be not less than the established number of tests in the area according to Table 2. and the distance between the places of impacts should not be less than 30 mm (15 mm for the shock pulse method). For the method of plastic deformation by indentation, the number of tests on each face should be at least two, and the distance between test sites should be at least two diameters of indentations.
When establishing the calibration dependence for the rib cleaving method, one test is carried out on each side rib.
When establishing the calibration dependence for the shear-off method, one test is carried out on each side face of the main bore.
6.3.6 When tested by the method of elastic rebound, shock impulse, plastic deformation upon impact, the samples shall be clamped in a press with a force of at least (30 ± 5) kN and not more than 10% of the expected value of the breaking load.
6.3.7 Pull-off test pieces are mounted on the press as follows. so that the surfaces on which the pull-out was carried out do not adhere to the support plates of the press. The test results in accordance with GOST 10180 increase by 5%.
7 Testing
7.1 General requirements
7.1.1 The number and location of controlled sections in structures must comply with the requirements of GOST 18105 and be indicated in the design documentation for the structure or be installed taking into account:
Control tasks (determination of the actual class of concrete, stripping or tempering strength, identification of areas of reduced strength, etc.);
Type of construction (columns, beams, slabs, etc.);
Placement of grips and concreting order:
Reinforcement of structures.
The rules for assigning the number of test sites for monolithic and prefabricated structures when monitoring concrete strength are given in Appendix I. When determining the concrete strength of the structures under study, the number and location of sites should be taken according to the survey program.
7.1.2 The tests are carried out on a construction site with an area of 100 to 900 cm.
7.1.3 The total number of measurements at each site, the distance between the measurement sites at the site and from the edge of the structure, the thickness of the structures at the site of measurements should be not less than the values given in Table 2, depending on the test method.
Table 2 - Requirements for test sites
|
Method name |
Total number of measurements in the area |
Minimum distance between places of measurements on the site, mm |
The minimum distance from the edge of the structure to the place of measurement, mm |
Minimum structure thickness, mm |
|
Elastic Bounce | ||||
|
Impact impulse | ||||
|
Plastic defomation | ||||
|
Scooping the rib | ||||
|
2 disc diameters | ||||
|
Tear-off with shearing at the working depth of the anchor embedment L: * 40mm< 40мм |
7.1.4 The deviation of individual measurement results in each section from the arithmetic mean of the measurement results for this section should not exceed 10%. Measurement results that do not satisfy the specified condition are not taken into account when calculating the arithmetic mean of the indirect indicator for a given area. The total number of measurements in each section when calculating the arithmetic mean must meet the requirements of Table 2.
7.1.5 The strength of concrete in the controlled area of the structure is determined by the average value of the indirect indicator according to the calibration dependence established in accordance with the requirements of section 6. provided that the calculated value of the indirect indicator is within the established (or tied) relationship (between the smallest and largest values strength).
7.1.6 The roughness of the surface of the concrete section of structures when tested by the methods of rebound, shock pulse, plastic deformation should correspond to the surface roughness of the sections of the structure (or cubes) tested when establishing the calibration dependence. If necessary, it is allowed to clean the surfaces of the structure.
When using the method of plastic deformation during indentation, if the zero reading is removed after applying the initial load, there are no requirements for the roughness of the concrete surface of the structure.
7.2 Rebound Method
7.2.1 The tests are carried out in the following sequence:
It is recommended to take the same position of the device when testing the structure relative to the horizontal. as in the establishment of the calibration dependence. In a different position of the device, it is necessary to correct for the indicators in accordance with the instructions for use of the device:
7.3 Method of plastic deformation
7.3.1 The tests are carried out in the following sequence:
The device is positioned so that the force is applied perpendicular to the test surface in accordance with the instructions for use of the device;
When using a spherical indentator to facilitate measurements of the diameters of the prints, the test is allowed to be carried out through sheets of copying and white paper (in this case, to establish the calibration dependence, carry out the test using the same paper);
The values of the indirect characteristic are recorded in accordance with the instructions for use of the device;
Calculate the average value of the indirect characteristic at the site of the structure.
7.4 Shock pulse method
7.4.1 The tests are carried out in the following sequence:
The device is positioned as follows. so that the force is applied perpendicular to the test surface * in accordance with the instructions for use of the device:
It is recommended that the position of the device during the test of the structure relative to the horizontal be taken the same as during the test when establishing the calibration dependence. In a different position of the device, it is necessary to correct for the readings in accordance with the instructions for use of the device;
The value of the indirect characteristic is recorded in accordance with the instructions for use of the device;
Calculate the average value of the indirect characteristic at the site of the structure.
7.5 Pull-off method
7.5.1 In the pull-off test, the sections shall be located in the zone of lowest stresses caused by the service load or the compression force of the prestressed reinforcement.
7.5.2 The test is carried out in the following sequence:
At the place of gluing the disc, remove the surface layer of concrete with a depth of 0.5-1 mm and clean the surface of dust;
The disc is adhered to the concrete by pressing the disc and removing excess adhesive outside the disc;
Lribor are connected with a disk;
The load is gradually increased with a speed of (1 ± 0.3) kN / s;
The readings of the force meter of the device are recorded;
Measure the projection area of the separation surface on the plane of the disk with an error of iO.Scm 2;
Determine the value of the conditional stress in the concrete during separation as the deviation of the maximum separation force to the projection area of the separation surface.
7.5.3 The test results are not taken into account if, when concrete was torn off, reinforcement was exposed or the projected area of the tearing surface was less than 80% of the disc area.
7.6 Pull-off method with chipping
7.6.1 When tested by the shear-off method, the sections shall be located in the zone of lowest stresses caused by the operational load or the compression force of the prestressed reinforcement.
7.6.2 The tests are carried out in the following sequence:
If the anchor device was not installed before concreting, then a hole is made in the concrete, the size of which is selected in accordance with the operating instructions for the device, depending on the type of anchor device;
An anchor device is fixed into the hole to a depth specified in the instruction manual for the device, depending on the type of anchor device;
The device is connected with a sanker device;
The load is increased at a speed of 1.5-3.0 kN / s:
The reading of the force meter of the device P 0 and the value of the LP anchor slip (the difference between the actual tear-out depth and the embedment depth of the anchor device) are recorded with an accuracy of not less than 0.1 mm.
7.6.3 The measured value of the pull-out force P 4 is multiplied by the correction factor y. determined by the formula
where L is the working depth of the anchor device embedment, mm;
DP - the amount of slip of the anchor, mm.
7.6.4 If the largest and smallest dimensions of the torn out part of the concrete from the anchor device to the destruction boundaries along the surface of the structure differ by more than two times, and also if the tear-out depth differs from the embedment depth of the anchor device by more than 5% (DL> 0.05ft, y> 1.1), then the test results can be taken into account only for an approximate assessment of the strength of concrete.
Note - Approximate values of concrete strength are not allowed to be used to assess the strength class of concrete and build calibration dependencies.
7.6.5 The test results are not taken into account if the tear-out depth differs from the embedment depth of the anchor device by more than 10% (dL> 0.1 A) or the reinforcement was exposed at a distance from the anchor device less than the embedment depth.
7.7 Rib shear method
7.7.1 When testing the rib shear method, there should be no cracks, concrete gaps, sagging or cavities with a height (depth) of more than 5 mm in the test area. The sections should be located in the zone of the lowest stresses caused by the operational load or the compression force of the prestressed reinforcement.
7.7.2 The test is carried out in the following sequence:
The device is secured to the structure. apply a load with a speed of light (1 ± 0.3) kN / s;
The reading of the power meter of the device is recorded;
Measure the actual shearing depth;
Determine the average shear force.
7.7.3 The test results are not taken into account if the reinforcement was exposed by the concrete shearing or the actual shearing depth differed from the specified one by more than 2 mm.
8 Processing and presentation of results
8.1 The test results are presented in a table, which indicates:
Type of construction;
Concrete design class;
Concrete age;
Strength of concrete of each controlled area according to 7.1.5;
Average concrete strength of the structure;
Zones of a structure or its part, subject to the requirements of 7.1.1.
The form of the test results presentation table is given in Appendix K.
8.2 Processing and assessment of compliance with the established requirements of the actual concrete strength values obtained using the methods given in this standard is carried out according to GOST 18105.
P rim in h in n and c - The statistical assessment of the class of concrete based on the test results is carried out in accordance with GOST 18105 (schemes "A". "B" or "C") in cases where the strength of concrete is determined by the calibration dependence built in in accordance with section 6. When using previously established dependencies by linking them (according to Appendix G), statistical control is not allowed, and the assessment of the concrete class is carried out only according to the scheme "G" GOST 18105.
8.3 The results of determining the strength of concrete by mechanical methods of non-destructive testing are drawn up in the conclusion (protocol), which contains the following data:
About tested structures, indicating the design class, the date of concreting and testing, or the age of the concrete at the time of testing;
On the methods used to control the strength of concrete;
On types of devices with serial numbers, information on instrument checks;
About the adopted calibration dependences (equation of dependence, parameters of dependence, compliance with the conditions for using the calibration dependence);
Used to construct a calibration dependence or its reference (date and results of tests by non-destructive indirect and direct or destructive methods, correction factors);
On the number of sites for determining the strength of concrete in structures with an indication of their location;
Test results;
Methodology, results of processing and evaluation of the data obtained.
Standard Shear Pull Test Arrangement
A.1 The standard shear peel test scheme provides for tests to be carried out in accordance with the requirements of A.2-A.6.
A.2 The standard test setup is applicable in the following cases:
Tests of heavy concrete with compressive strength from S to 100 MPa:
Testing lightweight concrete compressive strength from S to 40 MPa:
The maximum fraction of coarse concrete aggregate is not more than the working depth of the anchoring devices.
A.3 The supports of the loading device must adhere evenly to the concrete surface at a distance of at least 2h from the axis of the anchor device, where L is the working depth of the anchor device. The test setup is shown in Figure A.1.
1 - device with a loading device and a force-measuring device; 2 - support for the loading device: 3 - grip of the loading device: 4 - transition elements, rods, S - anchor device. 6 - concrete to be pulled out (taper): 7 - tested structure
Figure A.1 - Schematic of a shear peel test
A.4 Three types of anchor devices (see Figure A.2) are provided for in the standard shear-pull test setup. Anchoring device type I is installed in the structure during concreting. Anchoring devices of types II and ill are installed in holes previously prepared in the structure.
1 - working rod: 2 - working rod with frames with a different cone: 3 - segmented corrugated chips: 4 - support rod: 5 - working rod with a ripe expanding cone: b - leveling washer
Figure A.2 - Types of anchor devices for a standard test setup
A.5 Parameters of anchor devices and their allowable ranges of measured concrete strength at standard scheme tests are shown in Table A.1. For lightweight concrete, in the standard test scheme, only anchoring devices with an embedment depth of 48 mm are used.
Table A.1 - Parameters of anchor devices for the standard test scheme
|
Anchor device type |
Anchoring device diameter tf. mm |
Embedment depth of anchor devices, mm |
Permissible range for the anchor device for measuring the compressive strength of concrete. MPa |
||
|
speech h |
getting fat L " |
heavy | |||
A.b Structures of anchors of types II and III should provide preliminary (before the application of the load) compression of the hole walls at the working depth l and control of slippage after the test.
Standard rib shear test setup
B.1 The standard test scheme by the shear ribbing method provides for testing in compliance with the requirements of B.2-B.4.
B.2 The standard test scheme is applicable in the following cases:
Maximum fraction of coarse concrete aggregate no more than 40 mm:
Tests of heavy concrete with compressive strength from 10 to 70 MPa on granite and limestone crushed stone. B.3 For testing, use a device consisting of a power exciter with a power measurement unit.
crossbar and gripper with a bracket for local chipping of the rib of the structure. The test scheme is shown in Figure B.1.
1 - the device is a loading device and a measuring instrument. 2 - support frame: 3 - chipped concrete: 4 - tested
construction ^ - gripper with bracket
Figure B.1 - Schematic of the rib shear test
B.4 In case of local spalling of the rib, the following parameters should be provided:
Chipping depth a ■ (20 a 2) mm.
Chipping width 0 "(30 a 0.5) mm;
The angle between the direction of action of the load and the normal to the loaded surface of the structure p "(18 a 1) *.
Calibration dependence for the shear-off method with a standard test setup
When carrying out tests by the pull-off method with wellbore according to the standard scheme in accordance with Appendix A, the cubic strength of concrete is not compressive R. MPa. it is allowed to calculate according to the grvduirovanny dependence according to the formula
H * P) | P> ^. (IN 1)
where m is a coefficient that takes into account the maximum size of a coarse aggregate in the tear-out zone and is taken equal to 1 when the aggregate size is less than 50 mm:
t 2 is the proportionality coefficient for the transition from the pull-out force in kilonewtons to the concrete strength in megapascals:
P is the pull-out force of the anchor device. kN.
When testing heavy concrete with a strength of 5 MPa or more and light concrete with a strength of 5 to 40 MPa, the values of the proportionality coefficient m 2 are taken according to Table B.1.
Table 8.1
|
Anchor device type |
The range of measured compressive strength of concrete. MPa |
Anchor device diameter d. nor |
Embedment depth of anchor device, mm |
The value of the coefficient w ^ for concrete |
|
|
heavy | |||||
Coefficients m 3 when testing heavy concrete with medium strength above 70 MPa should be taken according to GOST 31914.
Calibration dependence for the rib shearing method with a standard test scheme
When performing the test by spalling ribs according to the standard scheme according to Appendix B, the cube compressive strength of concrete on granite and limestone crushed stone R. MLa. it is allowed to calculate by the calibration dependence according to the formula
R - 0.058m (30P + P J). (D. 1)
where m is a coefficient that takes into account the maximum size of a large aggregate and is taken equal to:
1.0 - with aggregate size less than 20 mm:
1.05 - with aggregate size from 20 to 30 mm:
1.1 - filler size from 30 to 40 mm:
P - shearing force. kN.
Appendix D (mandatory)
Requirements for instruments for mechanical testing
Table E.1
|
The name of the characteristics of the devices |
Characteristics of instruments for the method |
|||||||||||||||||||||||||||||||||||||
|
elastic |
percussion momentum |
plastic deformations |
otryaa with skapyaa * and it |
|||||||||||||||||||||||||||||||||||
|
The hardness of the striker, striker or indenter NYaSe. not less | ||||||||||||||||||||||||||||||||||||||
|
Roughness of the contact part of the striker or indenter. microns. no more | ||||||||||||||||||||||||||||||||||||||
|
The diameter of the striker or indenter. mm. not less | ||||||||||||||||||||||||||||||||||||||
|
The thickness of the edges of the disc indenter. mm. not less | ||||||||||||||||||||||||||||||||||||||
|
Conical indenter angle | ||||||||||||||||||||||||||||||||||||||
|
Imprint diameter,% of indenter diameter | ||||||||||||||||||||||||||||||||||||||
|
The perpendicularity tolerance when applying a load is not a height of 100 mm. mm | ||||||||||||||||||||||||||||||||||||||
|
Energy to impact. J. not less | ||||||||||||||||||||||||||||||||||||||
|
The rate of increase in the load. kN / s | ||||||||||||||||||||||||||||||||||||||
|
Load measurement error, Ch. No more |
5 here RjN - see the explication to the formula (£ .3). After rejection, the calibration dependence is established again according to the formulas (£ .1) - (E.S) according to the remaining test results. The rejection of the remaining test results is repeated considering the fulfillment of condition (E.6) using a new (corrected) calibration dependence. Particular values of concrete strength must meet the requirements of 6.1.7. £ .3 Parameters of calibration dependence For the adopted calibration dependence, determine: The minimum and maximum values of the indirect characteristic H gave. The standard deviation ^ n m of the constructed calibration dependence according to the formula (E.7); The correlation coefficient of the calibration dependence r according to the formula
where the average value of concrete strength according to the calibration dependence is calculated according to the form
here the values of R (H. I f. I f. N - see the explication to the formulas (EE). (Eb). E.4 Correction of the calibration dependence Correction of the established calibration dependence, taking into account the additionally obtained test results, should be carried out at least once a month. When adjusting the calibration dependence, at least three new results obtained at the minimum, maximum and intermediate values of the indirect indicator are added to the existing test results. As data accumulates for plotting the calibration dependence, the results of previous tests. starting from the very first, they are rejected so that total number results did not exceed 20. After adding new results and rejecting old ones, the minimum and maximum values of the indirect characteristic, the calibration dependence and its parameters are set again according to formulas (E.1) - (E.9). E.S Conditions for the application of the calibration curve The use of a calibration dependence for determining the strength of concrete in accordance with this standard is allowed only for values of an indirect characteristic falling in the range from H tl to n tad. If the correlation coefficient r< 0.7 или значение 5 тнм "Я ф >0.15. then control and assessment of strength according to the obtained dependence are not allowed. Calibration dependence binding method G.1 The value of concrete strength, determined using the calibration dependence established for concrete that differs from the tested one, is multiplied by the coincidence coefficient Kc. The value is calculated according to the form where is the strength of concrete in t-th section, determined by the method of shearing off or by testing of cores according to GOST 26570; I msa, is the strength of concrete in<-м участке, опредепяемвя пюбым косвенным методом по используемой градуировочной зависимости: л - число участков испытаний. G.2 When calculating the coincidence coefficient, the following conditions must be met: The number of test sites taken into account when calculating the coincidence coefficient, n i 3; Each particular value R k, / R (0ca ^ should be at least 0.7 and not more than 1.3: Each particular value of R ^. , should differ from the average by no more than 15%: Yade values not satisfying conditions (G.2). (ZH). should not be taken into account in the calculation the coefficient of coincidence K s. Assignment of the number of test sites for prefabricated and monolithic structures I.1 In accordance with GOST 18105, when controlling the strength of concrete of prefabricated structures (tempering or relocating), the number of controlled structures of each type shall be taken at least YuCh and at least ^ structures from the batch. If a batch consists of 12 structures or less, a continuous inspection is carried out. In this case, the number of sections must be at least: 1 not 4 m lengths of linear structures: 1 by 4 m 2 of the area of flat structures. I.2 In accordance with GOST 18105, when controlling the strength of concrete of monolithic structures at an intermediate age by non-destructive methods, at least one structure of each type (column, wall, ceiling, crossbar, etc.) from the controlled batch is controlled. I.3 In accordance with GOST 18105, when controlling the strength of concrete of monolithic structures at the design age, continuous nerve-breaking control of the strength of concrete of all structures of the controlled batch is carried out. In this case, the number of test sites must be at least: 3 for each gripper for flat structures (wall, floor, foundation slab); 1 x 4 m length (or 3 per grip) for each linear horizontal structure (beam, crossbars); 6 for each structure - for linear vertical structures (column, pylon). The total number of measurement sites for calculating the characteristics of the uniformity of the strength of concrete in a batch of structures must be at least 20. I.4 The number of single measurements of the strength of concrete by mechanical methods of non-destructive testing at each site (the number of measurements at the site) is taken according to Table 2. Form of the table of presentation of test results
UDC 691.32.620.17:006.354 MKS 91.100.10 NEQ Key words: structural heavy and light concrete, monolithic and prefabricated concrete and iron * concrete products, structures and structures, mechanical methods for determining compressive strength, rebound, shock impulse, plastic deformation, separation, rib shearing, shearing off with shearing Editor T.T. Martynova Technical editor 8.N. Prusakova Proofreader M 8. Vuchaya Computer layout I.А. Napaykina Donated to the set 12/29/201S. Signed and stamped on 06.02.2016. Format 60 "64 ^. Arial headset. Uel. print l. 2.7B. Uch.-iad. l. 2.36. Tira "60 eke. Zach. 263. Published and printed by FGUP STANDARTINFORM, $ 12399 Moscow. Granatny lane .. 4. | |||||||||||||||||||||||||||||||||||||
