Concrete testing GOST 18105. Determination of the required strength and the actual strength class of concrete
GOST 18105-86 establishes the rules for determining the characteristics of concretes - structural heavy, lightweight and cellular (including structural and heat-insulating), dense silicate, as well as concretes used for the production of prefabricated and monolithic concrete and reinforced concrete structures. GOST 18105-86 applies to testing concrete for compression, axial tension, and bending tension. Entered into force on 01.01.87.
STRENGTH CONTROL RULES
GOST 18105-86
MINSTROY OF RUSSIA
Group W19
STATE STANDARD OF THE UNION OF SSR
Strength control rules GOST 18105 - 86
Concretes. Rules for the strength control
Date of introduction 01.01. 87
This standard applies to structural heavy, light and cellular (including structural and thermal insulation), as well as dense silicate concrete of prefabricated and monolithic concrete and reinforced concrete products, structures and structures (hereinafter referred to as structures) and establishes rules for controlling the strength of concrete in compression, axial tension and bending tension (hereinafter referred to as strength).
The rules for controlling the strength of concrete, established by the standard, can be applied to tensioning, as well as to other types of special concretes, provided that the coefficients of the required strength of these concretes correspond to those adopted in the standard.
When controlling the strength of concrete in accordance with this standard, the design and standard resistances of concrete adopted during the design of the structure are provided with a minimum consumption of cement.
Explanations for the terms used in this standard are given in Appendix 1.
Reissue with Change
This standard cannot be fully or partially reproduced, replicated and distributed without the permission of the Ministry of Construction of Russia.
1. BASIC PROVISIONS
1.1. At enterprises in the manufacture of concrete mix and the production of prefabricated structures, as well as at construction sites when concreting monolithic structures, statistical control and acceptance of concrete for strength, taking into account homogeneity, must be carried out in accordance with the requirements of this standard.
Acceptance of concrete by comparing its actual strength with the standardized one, without taking into account the characteristics of homogeneity of strength, is not allowed.
1.2. Subject to control:
- Tempering strength of concrete - for prestressed prefabricated structures and prestressed prefabricated structures, if the tempering strength is higher than the transfer strength;
- transfer strength of concrete - for prestressed structures;
- the strength of concrete in the intermediate age established by the design documentation - for monolithic structures (when removing the bearing formwork, etc.);
- strength of concrete at design age - for prefabricated and monolithic structures.
In cases where the normalized tempering or transfer strength of concrete is 90% or more of that established for a given class (grade), the strength control at the design age is not performed.
1.3. The control of concrete strength for each type of rated strength specified in clause 1.2 is carried out using the control data of previous batches in the following order:
- determine the strength of concrete in each of the batches made during the period established by the standard (analyzed);
- calculate the characteristics of the homogeneity of the strength of concrete for the analyzed period;
- the required concrete strength for the next controlled period is determined by the characteristics of the homogeneity of the concrete strength in the analyzed period;
- determine the strength of concrete in a given controlled batch, compare it with the required strength and make a decision on the acceptance of this batch.
1.4. The strength of concrete in a batch is determined in accordance with this standard based on the results of testing concrete samples in accordance with GOST 10180 (hereinafter referred to as control by samples) or by non-destructive methods in accordance with the current state standards for these methods.
When determining the strength of concrete of monolithic structures by non-destructive methods, either the ultrasonic method in accordance with GOST 17624 with through sounding, or the method of separation with spalling in accordance with GOST 22690 should be used. The use of other methods of non-destructive testing is allowed by agreement with the leading research organizations.
The tensile strength of concrete, and at the design age of prefabricated concrete and in compression, is determined only from samples.
1.5. As a characteristic of homogeneity used in the control to determine the required strength of concrete RT, calculate the average coefficient of variation of strength Vn for all batches of concrete for the analyzed period.
1.6. Simultaneously with the determination of the required strength, the average level of concrete strength R y is calculated for use in the selection of the concrete composition in accordance with GOST 27006 for the forthcoming controlled period.
At the same time, if the average level of concrete strength in the forthcoming controlled period decreases in comparison with the previous one (due to the production of concrete with a higher homogeneity), then the cement consumption should be reduced accordingly.
2. DETERMINATION OF CONCRETE STRENGTH IN A LOT
2.1. The batch should include concrete of prefabricated or monolithic structures, formed on one technological complex from a concrete mixture of the same nominal composition according to GOST 27006 using one technology for at least one shift and not more than one week.
When inspecting by samples, the composition of a batch of concrete for prefabricated structures may include concrete from one or several batches of structures formed in accordance with the current standards or specifications for these structures.
When determining the strength of concrete of prefabricated structures by non-destructive methods, the composition of the batch includes the concrete of one batch of structures.
2.1a. It is allowed to combine concretes of the same class (brand) in terms of strength of different nominal composition as part of a batch, if the following conditions are met:
- the maximum of the average values of the batch coefficient of variation of concrete strength for the analyzed period of the combined compositions does not exceed 12%;
- the difference between the maximum and minimum values of the batch coefficient of variation of concrete strength for the analyzed period for the combined compositions does not exceed 2%;
- the largest aggregate size and workability index of the combined compositions differ by no more than two times, and the cement consumption in these compositions differs by no more than 15% from the average value.
The regulated conditions of association are checked once a year based on the results of determining statistical characteristics homogeneity of concrete in terms of strength separately for each nominal composition for the last two controlled periods.
When combining different compositions into a batch, the value of the coefficient of variation of the strength of concrete in the first controlled period is determined as the arithmetic mean of the averaged values of the coefficients of variation for individual nominal compositions.
(Introduced additionally, Amendment No. 1).
2.2. When testing on samples to determine the strength of concrete from randomly selected mixes in accordance with GOST 10181.0, at least two samples of the concrete mixture are taken from each batch of concrete (with the exception of aerated concrete) and at least one sample;
- per shift - at the factory - manufacturer of prefabricated structures;
- in 1 day - at the enterprise - manufacturer of concrete mix for monolithic structures;
- in 1 day - for construction site for monolithic structures.
By agreement with the design organization carrying out field supervision, it is allowed not to take samples of the concrete mixture at the place of their placement in the monolithic structure, but to evaluate the strength of concrete according to the control data of the enterprise - the manufacturer of the concrete mixture.
2.3. Each sample of the concrete mixture is made in accordance with GOST 10180, one series of concrete samples to control: - Tempering strength; - transfer strength; - the strength of concrete at an intermediate age; - the strength of concrete at the design age. It is allowed to make a series of control samples for determining the strength of concrete of prefabricated structures at the design age, not from each sample, but from at least two samples taken from one batch per week with concrete strength class B30 (grade 400) and below, and four samples, selected from two batches per week with concrete strength class B35 (grade 450) and higher.
To control the strength of aerated concrete made of ready-made structures for each batch or from blocks made simultaneously with these structures, at least two series of samples are cut out or drilled out in accordance with GOST 10180.
2.4. Control samples of concrete of prefabricated structures must be hardened in the same conditions as the structures before determining the tempering or transfer strength. Subsequent hardening of samples intended to determine the strength of concrete at the design age should be carried out under normal conditions at a temperature of (20 ± 2) ° C and a relative humidity of at least 95%.
Control samples of concrete of monolithic structures at the enterprise - the manufacturer of the concrete mixture must harden under normal conditions, and at the construction site - under conditions identical to the conditions of hardening of structures.
2.5. When inspecting by non-destructive methods, to determine the tempering or transfer strength of concrete of prefabricated structures, 10% are taken from the batch, but not less than three structures.
To determine the strength of concrete of monolithic structures by non-destructive methods at an intermediate age, at least one structure from the volume of concrete laid during every day is controlled (or part of the structure in the case when it is concreted for more than 1 day).
2.6. On each prefabricated structure selected for determining the strength of concrete by non-destructive methods, at least two are assigned, and for a monolithic structure - at least four controlled areas.
The number and location of controlled areas must be indicated by the design organization in the working drawings of structures, depending on the geometric dimensions, purpose and technology of their manufacture and be not less than:
- for linear structures - one section per 4 m length;
- for flat structures, with the exception of monolithic structures of solid walls - one section per 4 m2 of area;
- for monolithic structures of solid walls - one area per 8 m2 of area.
In the absence of instructions in the working drawings, the controlled areas are established by the manufacturer in agreement with the design or research organization.
The number of measurements performed at each controlled area is taken according to the current standards for non-destructive testing methods.
2.7. The strength of concrete in a batch (R m), MPa, is calculated by the formula
(1)
where R i is the unit value of concrete strength, MPa;
n is the total number of unit values of concrete strength in the batch.
The unit value of concrete strength is taken as follows:
- when controlled by samples - the average strength of concrete in one series of samples, determined in accordance with GOST 10180;
- when testing by non-destructive methods - the average strength of the concrete of the structure or the average strength of the concrete of the controlled section of the structure, determined according to the current state standards for non-destructive testing methods. Guidelines for the selection of the type of single strength value for use non-destructive methods are given in Appendix 2.
3. DETERMINATION OF CONCRETE UNIFORMITY CHARACTERISTICS BY STRENGTH
3.1. The duration of the analyzed period to determine the characteristics of the homogeneity of concrete is set from one week to 2 months. The number of unit values of concrete strength during this period must be at least 30.
3.2. During the analyzed period, for each batch of concrete, calculate the average standard deviation S m and coefficient of variation V m strength. The specified characteristics are calculated for all types of rated strength according to clause 1.2. At the same time, it is allowed not to calculate the coefficient of variation of the strength of concrete at the design age for prefabricated structures, but to take it equal to 85% of the coefficient of variation of the tempering strength.
3.3. When testing samples, the standard deviation of concrete strength in a batch (Sm), MPa, when the number of unit values of concrete strength in a batch is more than six, is calculated by the formula
, (2)
If the number of unit values of concrete strength in a batch is from two to six, the value of Sm is calculated by the formula
(3)
where Wm is the range of unit values of concrete strength in a controlled batch, defined as the difference between the maximum and minimum unit values of strength, MPa;
a - coefficient depending on the number of single values (n) and taken from table. one.
Table 1
When testing by non-destructive methods in the case when the average strength of the concrete of the structure is taken as a unit value, the value of S t, MPa, is calculated taking into account the deviations of the calibration dependence by the formula
, (4)
where S T is the standard deviation of the calibration dependence, determined according to the current state standards for non-destructive methods, MPa;
n is the number of single values (controlled structures) in the batch;
p is the number of controlled areas in the structure. In the case when the strength of concrete in the controlled area is taken as a unit value, the value of Sm, MPa, is calculated by the formula
, (5)
where K n - correction factor, determined according to Appendix 2;
n is the number of unit values of concrete strength (controlled areas) in the batch.
3.4. The coefficient of variation of the strength of concrete in the batch (batch coefficient) (V m) in percent is calculated by the formula
(6)
3.5. The average value of the batch coefficient of variation of concrete strength for the analyzed period (p) in percent is calculated by the formula
,
(7)
where V m, i - coefficients of variation of concrete strength in each i-th of n batches of concrete controlled during the analyzed period, calculated by the formula (6);
n i - the number of unit values of concrete strength in each i-th of n batches of concrete, controlled during the analyzed period;
- the total number of unit values of concrete strength for the analyzed period (at least 30).
3.6. When controlling the strength of concrete at a construction site, the coefficient of variation of the strength of concrete is taken according to the document on the quality of the concrete mixture of the manufacturer.
3.7. It is allowed for the control of irregularly produced prefabricated structures and concrete mixtures to take the coefficient of variation equal to the coefficient of variation of concrete of a different composition, provided that it is manufactured using the same technology and on the same materials and differing in strength by no more than two classes (grades).
4. DETERMINATION OF THE REQUIRED CONCRETE STRENGTH
4.1. The required strength of concrete (tempering, transfer, in intermediate or design ages) when normalizing strength by classes (Pt), MPa, is calculated by the formula
R T = K T B norm, (8)
where B norms is the normalized value of concrete strength (tempering, transfer, at intermediate or design age) for concrete of a given class in terms of compressive strength, axial tension or bending tension, MPa;
K T is the coefficient of the required strength for all types of concrete, taken in accordance with table. 2 depending on the average coefficient of variation of concrete strength V n for all batches for the analyzed period, calculated by the formula (7).
When using non-destructive methods for controlling the strength of concrete in cases where the strength of concrete of the controlled section of the structure is taken as a unit value, right side formulas (8) should be multiplied by a factor equal to 0.95.
4.2. The required strength of concrete when normalizing strength by grade is determined in accordance with Appendix 3.
table 2
|
V n% |
for all types of concrete (except for dense silicate, cellular) and structures, except for massive hydraulic engineering |
|||
|
Invalid Scope |
||||
|
values |
||||
|
21 and more |
||||
4.3. If necessary, control the strength of the concrete individual. batches the coefficient of the required strength can be taken from table. 2 or the table in Appendix 3, depending on the coefficient of variation of the strength of concrete in a given batch, calculated by the formula (6). Moreover, the number of unit values of concrete strength in this batch must be at least 30.
4.4. In the initial period before the accumulation of the number of test results required for conducting statistical control, the required concrete strength (R T) is determined by the formula
R T = 
(10)
where KB is the coefficient taken according to the table. 3 depending on the type of concrete.
Table 3
4.5. The duration of the controlled period during which the specified value of the required strength can be used should be taken from one week to 1 month.
5. RECEPTION OF CONCRETE BY STRENGTH
5.1. Lots of prefabricated concrete are accepted according to the release and transfer strength, and monolithic structures - according to the strength of concrete at the design age.
5.2. A batch of concrete is subject to acceptance if the actual strength of concrete in the batch (R m) is not lower than the required strength (R?), I.e.
R m? R? (eleven)
5.3. The control of ensuring the strength of concrete of prefabricated structures at the design age is carried out periodically within the timeframes specified in clause 2.3, by comparing the required strength at the design age with the average strength of concrete at this age of all batches monitored during the week.
The strength of concrete of prefabricated structures at the design age is recognized as meeting the requirements of this standard if the condition of formula (11) is met. At the same time, the test results refer to all batches of concrete made in a week.
In case of violation of this condition, the manufacturer is obliged to inform the consumer about this within three days after the end of all tests.
5.4. The possibility of using batches of structures whose concrete strength does not meet the requirements of paragraphs. 5.2 and 5.3, must be agreed with the design organization.
The same agreement is necessary for the further manufacture and use of structures, if the average batch coefficient of variation for the next controlled period falls into the area of unacceptable values.
5.3, 5.4. (Modified edition, Amendment No. 1).
5.5. The values of the actual and required concrete strength should be indicated in the document on the quality of the batch of prefabricated structures in accordance with GOST 13015.3 or concrete mixture in accordance with GOST 7473 and in the magazine concrete works for monolithic structures.
6. DETERMINATION OF THE AVERAGE LEVEL OF CONCRETE STRENGTH
6.1. The average for the controlled period the level of strength of the tempering, transfer for prefabricated structures, at intermediate and design age for monolithic structures) of concrete (R?), MPa, is determined by the formula
R y = R? K m.p, (12)
where Km.p is the coefficient taken according to the table. 4 depending on the average for the analyzed period of the coefficient of variation V n.
In this case, the Km.p value should be taken for heavy and light concrete no more than 1.10, and for dense silicate concrete - no more than 1.13.
6.2. It is allowed to exceed the actual average concrete strength of prefabricated structures at the design age ( 
) over the required ( 
), which is characterized by the coefficient (Kv) calculated by the formula
(13)
The values of Kv, calculated by the formula (13), are compared with the values given in the table of Appendix 4.
(Modified edition, Amendment No. 1).
6.3. In cases where the concrete selected by the manufacturer's laboratory based on the conditions for ensuring the design grade for water resistance, frost resistance or other requirements, must have an average strength higher than the average strength level at the design age calculated by formula (12), then as an average level take the strength determined during the selection of the composition.
6.4. The upper warning limit of the average strength of concrete in a controlled batch ( 
), MPa, the excess of which indicates an overestimation of the actual strength, is calculated by the formula
, (14)
where V m.p - coefficient of inter-batch variation of strength, taken equal to 0.5 V n.
6.5. If the strength of concrete is higher in three batches in a row 
or the actual average level of strength for the controlled period exceeds the average level of strength calculated by formula (12), or the value of the coefficient Kv, determined by formula (13), is higher than the values given in Appendix 4, then measures should be taken to reduce the strength of concrete and reduction of cement consumption.
ANNEX 1
Reference
BASIC TERMS, EXPLANATIONS AND SYMBOLS
|
Symbol |
Explanation |
|
|
1.Rated strength of concrete |
Specified in the normative and technical or project documentation strength value (at design and intermediate age, vacation, gear) |
|
|
2. Required concrete strength |
The minimum permissible value of the actual strength of concrete in a batch, established by the laboratories of enterprises and construction sites in accordance with the achieved uniformity |
|
|
3. Actual strength of concrete in a batch |
The average value of the strength of concrete in a batch, determined from the results of testing control samples or non-destructive methods directly in the structure |
|
|
4. Average level of concrete strength |
The average value of the strength of concrete, established by the laboratories of enterprises and construction sites for a certain controlled period in accordance with the achieved uniformity of concrete in terms of strength, for which its composition is selected and which is maintained in production |
|
|
5. Design age of concrete |
The time of concrete hardening established in the normative-technical or design documentation, during which the strength corresponding to its class or brand must be achieved |
|
|
According to GOST 10180 and GOST 10181.0 |
||
|
7. Sample series |
According to GOST 10180 |
|
|
8. Controlled area |
The section of the structure where measurements are taken during the control of concrete strength by non-destructive methods |
|
|
9. Analyzed period |
The time period over which the batch average strength coefficient of variation is calculated to assign the required strength over a subsequent controlled period |
|
|
10. Controlled period |
The period of time during which the required strength is taken constant in accordance with the coefficient of variation for the previous analyzed period |
|
|
11. Technological complex |
One of several technological lines plants for which the control of the strength of concrete of the same nominal composition, prepared according to the same technology and hardened under the same conditions, is carried out according to one batch coefficient of variation V n, calculated for the analyzed period |
APPENDIX 2
Mandatory
ADDITIONAL REQUIREMENTS FOR CONTROL OF CONCRETE STRENGTH BY NON-DESTRUCTIVE METHODS
1. For a unit value at non-destructive testing accept:
- when inspecting the structures of flat and hollow-core floor slabs and pavements, road slabs, interior panels load-bearing walls, wall blocks, as well as pressure and non-pressure pipes - the average strength of the concrete of the structure, calculated as the arithmetic mean of the concrete strength of the controlled sections of the structure;
- in all other cases, including monolithic and precast-monolithic structures, - the average concrete strength of the controlled section of the structure (or part of a monolithic, prefabricated monolithic construction).
2. The control of concrete strength by non-destructive methods (ultrasonic pulse or mechanical) in the case when the average strength of the concrete of the structure is taken as a unit value is carried out using a calibration dependence previously established in accordance with the requirements of the current state standards to these methods.
3. The control of concrete strength by non-destructive methods in the case when the average concrete strength of the controlled area is taken as a unit value is carried out using the correction factor Кп in the formula (5) of Sec. 3, which is determined before starting the transition to these methods with each change in the nominal composition of concrete, construction technology, type of materials used, with each new establishment of the calibration dependence, but at least once a year.
The coefficient Kp is calculated by the formula
Kp = 
,
where V n.m - the coefficient of variation of the strength of concrete of all series of samples tested by a non-destructive method to establish the calibration dependence;
V o - coefficient of variation of concrete strength of the same series of samples ,. tested by loading to establish the calibration dependence.
To establish the calibration dependence, the value of the coefficients of variation Vo and V n.m. is determined by a formula similar to formula (7) of section. 3.
APPENDIX 3
Mandatory
DETERMINATION OF THE REQUIRED STRENGTH OF CONCRETE WHEN RATING IT BY GRADES
1. The required strength of concrete (tempering, transfer, at intermediate or design age) when normalizing strength by grade (RT), MPa, is calculated by the formula
R Т = R norms 
,
(1)
where R norms is the normalized value of concrete strength (tempering, transferring, at intermediate or design age) for concrete of a given grade in terms of compressive strength, axial tension or bending tension, MPa;
К? Т is the coefficient of the required strength in percent for all types of concretes, taken in accordance with the table of this appendix, depending on the average batch coefficient of variation of the strength of concrete V n for the analyzed period, calculated according to the formula (7) section. 3.
|
V n% |
for all types of concrete (except for dense silicate cellular concrete) and structures, except for massive hydraulic engineering |
for dense silicate concrete |
for autoclaved aerated concrete |
for massive hydraulic structures |
|
Invalid Scope |
||||
|
values |
||||
|
21 and more |
||||
When using non-destructive methods for controlling the strength of concrete in cases where the strength of concrete of the controlled section of the structure is taken as a unit value, the right-hand side of formula (1) should be multiplied. by a coefficient equal to 0.95.
2. In the initial period before the accumulation of the number of test results required for conducting statistical control, m is determined by the formula
R t = 1.1? R norm. (2)
3. The duration of the controlled period is taken in accordance with clause 4.5 of this standard.
APPENDIX 4
Reference
VALUE OF Kv COEFFICIENT FOR CONCRETE of prefabricated structures
The values of the Kv coefficient for heavy concrete are given in the table.
|
Class or grade of concrete |
Duration of heat treatment, h |
cement by the efficiency of heat treatment in accordance with GOST |
Normalized tempering strength, as a percentage of the class or grade of concrete |
|||
|
B 15 or M200 and below |
1,15 |
|||||
|
l, 00 l, 05 |
l, 20 |
|||||
|
l, 00 l, 05 |
1,20 |
|||||
|
B20, B25 or M250 and M300 |
l, 25 |
|||||
|
B30, B35, B40 or M350, M400, M450 and M500 |
||||||
|
Note. When the Kw coefficient is more than 1.00, technological measures should be applied (lengthen the heat treatment cycle, apply additives that accelerate the hardening of concrete, or apply more efficient cements etc.), aimed at increasing the strength of concrete after heat treatment and reducing the consumption of cement. 2. For lightweight concretes of classes B7.5 (grades M100) and less, the value of Kv is taken equal to 1. For lightweight concretes of classes B10 (grades M150) and more, the value of Kv is taken according to the table for heavy concrete multiplied by a factor of 0.85 when using porous aggregates with a strength grade less than a concrete grade. In this case, the value of Kv in all cases should not be less than 1. |
||||||
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Scientific Research Institute of Concrete and Reinforced Concrete (NIIZhB) of the USSR State Construction Committee
DEVELOPERS
M.I.Brusser, Cand. tech. Sciences (topic leader); V. A. Dorf, Cand. tech. sciences; A. G. Malinovsky, V. V. Tishenko, I. N. Nagornyak
2. APPROVED AND PUT INTO EFFECT by the Decree of the State Committee of the USSR for Construction Affairs dated 13.08.86 No. 108
3. REPLACE GOST 18105.0 - 80, GOST 18105.1-80, GOST 18105.2 - 80 and GOST 13015 - 75 in terms of tensile strength control
4. REFERENCE REGULATORY AND TECHNICAL DOCUMENTS
5. REPUBLICATION (May 1992) with Amendment No. 1, approved in December 1987 (IUS 4 - 88)
STATE STANDARD OF THE UNION OF SSR
CONCRETE
STRENGTH CONTROL RULES
GOST 18105-86
MINSTROY OF RUSSIA
Group W19
STATE STANDARD OF THE UNION OF SSR
CONCRETE
Strength control rules GOST 18105 - 86
Concretes. Rules for the strength control
Date of introduction 01.01.87
This standard applies to structural heavy, light and cellular (including structural and thermal insulation), as well as dense silicate concrete of prefabricated and monolithic concrete and reinforced concrete products, structures and structures (hereinafter referred to as structures) and establishes rules for controlling the strength of concrete in compression, axial tension and bending tension (hereinafter referred to as strength).
The rules for controlling the strength of concrete, established by the standard, can be applied to tensioning, as well as to other types of special concretes, provided that the coefficients of the required strength of these concretes correspond to those adopted in the standard.
When controlling the strength of concrete in accordance with this standard, the design and standard resistances of concrete adopted during the design of the structure are provided with a minimum consumption of cement.
Explanations for the terms used in this standard are given in Appendix 1.
Reissue with Change
This standard cannot be fully or partially reproduced, replicated and distributed without the permission of the Ministry of Construction of Russia.
1. BASIC PROVISIONS
1.1. At enterprises in the manufacture of concrete mix and the production of prefabricated structures, as well as at construction sites when concreting monolithic structures, statistical control and acceptance of concrete for strength, taking into account homogeneity, must be carried out in accordance with the requirements of this standard.
Acceptance of concrete by comparing its actual strength with the standardized one, without taking into account the characteristics of homogeneity of strength, is not allowed.
1.2. Subject to control:
- Tempering strength of concrete - for prestressed prefabricated structures and prestressed prefabricated structures, if the tempering strength is higher than the transfer strength;
- transfer strength of concrete - for prestressed structures;
- the strength of concrete in the intermediate age established by the design documentation - for monolithic structures (when removing the bearing formwork, etc.);
- strength of concrete at design age - for prefabricated and monolithic structures.
In cases where the normalized tempering or transfer strength of concrete is 90% or more of that established for a given class (grade), the strength control at the design age is not performed.
1.3. The control of concrete strength for each type of rated strength specified in clause 1.2 is carried out using the control data of previous batches in the following order:
- determine the strength of concrete in each of the batches made during the period established by the standard (analyzed);
- calculate the characteristics of the homogeneity of the strength of concrete for the analyzed period;
- the required concrete strength for the next controlled period is determined by the characteristics of the homogeneity of the concrete strength in the analyzed period;
- determine the strength of concrete in a given controlled batch, compare it with the required strength and make a decision on the acceptance of this batch.
1.4. The strength of concrete in a batch is determined in accordance with this standard based on the results of testing concrete samples in accordance with GOST 10180 (hereinafter referred to as control by samples) or by non-destructive methods in accordance with the current state standards for these methods.
When determining the strength of concrete of monolithic structures by non-destructive methods, either the ultrasonic method in accordance with GOST 17624 with through sounding, or the method of separation with spalling in accordance with GOST 22690 should be used. The use of other methods of non-destructive testing is allowed by agreement with the leading research organizations.
The tensile strength of concrete, and at the design age of prefabricated concrete and in compression, is determined only from samples.
1.5. As a characteristic of homogeneity used in control to determine the required strength of concrete RT, calculate the average coefficient of variation of strength Vn for all batches of concrete for the analyzed period.
1.6. Simultaneously with the determination of the required strength, the average level of concrete strength is calculated Ry for use in the selection of concrete composition in accordance with GOST 27006 for the upcoming controlled period.
At the same time, if the average level of concrete strength in the forthcoming controlled period decreases in comparison with the previous one (due to the production of concrete with a higher homogeneity), then the cement consumption should be reduced accordingly.
2. DETERMINATION OF CONCRETE STRENGTH IN A LOT
2.1. The batch should include concrete of prefabricated or monolithic structures, formed on one technological complex from a concrete mixture of the same nominal composition according to GOST 27006 using one technology for at least one shift and not more than one week.
When inspecting by samples, the composition of a batch of concrete for prefabricated structures may include concrete from one or several batches of structures formed in accordance with the current standards or specifications for these structures.
When determining the strength of concrete of prefabricated structures by non-destructive methods, the composition of the batch includes the concrete of one batch of structures.
2.1a. It is allowed to combine concretes of the same class (brand) in terms of strength of different nominal composition as part of a batch, if the following conditions are met:
- the maximum of the average values of the batch coefficient of variation of concrete strength for the analyzed period of the combined compositions does not exceed 12%;
- the difference between the maximum and minimum values of the batch coefficient of variation of concrete strength for the analyzed period for the combined compositions does not exceed 2%;
- the largest aggregate size and workability index of the combined compositions differ by no more than two times, and the cement consumption in these compositions differs by no more than 15% from the average value.
The regulated conditions of association are checked once a year according to the results of determining the statistical characteristics of the homogeneity of concrete in terms of strength separately for each nominal composition for the last two controlled periods.
When combining different compositions into a batch, the value of the coefficient of variation of the strength of concrete in the first controlled period is determined as the arithmetic mean of the averaged values of the coefficients of variation for individual nominal compositions.
(Introduced additionally, Amendment No. 1).
2.2. When testing on samples to determine the strength of concrete from randomly selected mixes in accordance with GOST 10181.0, at least two samples of the concrete mixture are taken from each batch of concrete (with the exception of aerated concrete) and at least one sample;
- per shift - at the factory - manufacturer of prefabricated structures;
- in 1 day - at the enterprise - manufacturer of concrete mix for monolithic structures;
- in 1 day - at the construction site for monolithic structures.
By agreement with the design organization carrying out field supervision, it is allowed not to take samples of the concrete mixture at the place of their placement in the monolithic structure, but to evaluate the strength of concrete according to the control data of the enterprise - the manufacturer of the concrete mixture.
2.3. Each sample of the concrete mixture is made in accordance with GOST 10180, one series of concrete samples to control: - Tempering strength; - transfer strength; - the strength of concrete at an intermediate age; - the strength of concrete at the design age. It is allowed to make a series of control samples for determining the strength of concrete of prefabricated structures at the design age, not from each sample, but from at least two samples taken from one batch per week with concrete strength class B30 (grade 400) and below, and four samples, selected from two batches per week with concrete strength class B35 (grade 450) and higher.
To control the strength of aerated concrete, at least two series of samples are cut out or drilled out from the finished structures of each batch or from blocks made simultaneously with these structures in accordance with GOST 10180.
2.4. Control samples of concrete of prefabricated structures must be hardened in the same conditions as the structures before determining the tempering or transfer strength. Subsequent hardening of samples intended to determine the strength of concrete at the design age should be carried out under normal conditions at a temperature of (20 ± 2) ° C and a relative humidity of at least 95%.
Control samples of concrete of monolithic structures at the enterprise - the manufacturer of the concrete mixture must harden under normal conditions, and at the construction site - under conditions identical to the conditions of hardening of structures.
2.5. When inspecting by non-destructive methods, to determine the tempering or transfer strength of concrete of prefabricated structures, 10% are taken from the batch, but not less than three structures.
To determine the strength of concrete of monolithic structures by non-destructive methods at an intermediate age, at least one structure from the volume of concrete laid during every day is controlled (or part of the structure in the case when it is concreted for more than 1 day).
2.6. On each prefabricated structure selected for determining the strength of concrete by non-destructive methods, at least two are assigned, and for a monolithic structure - at least four controlled areas.
The number and location of controlled areas must be indicated by the design organization in the working drawings of structures, depending on the geometric dimensions, purpose and technology of their manufacture and be not less than:
- for linear structures - one section per 4 m length;
- for flat structures, with the exception of monolithic structures of solid walls, - one area per 4 m2 of area;
- for monolithic structures of solid walls - one area per 8 m2 of area.
In the absence of instructions in the working drawings, the controlled areas are established by the manufacturer in agreement with the design or research organization.
The number of measurements performed at each controlled area is taken according to the current standards for non-destructive testing methods.
2.7. Strength of concrete in a batch ( Rm), MPa, calculated by the formula
where Ri - unit value of concrete strength, MPa;
P - the total number of unit values of concrete strength in the batch.
The unit value of concrete strength is taken as follows:
- when controlled by samples - the average strength of concrete in one series of samples, determined in accordance with GOST 10180;
- when testing by non-destructive methods - the average strength of the concrete of the structure or the average strength of the concrete of the controlled section of the structure, determined according to the current state standards for non-destructive testing methods. Guidelines for choosing the type of unit strength value when using non-destructive methods are given in Appendix 2.
3. DETERMINATION OF CONCRETE UNIFORMITY CHARACTERISTICS BY STRENGTH
3.1. The duration of the analyzed period to determine the characteristics of the homogeneity of concrete is set from one week to 2 months. The number of unit values of concrete strength during this period must be at least 30.
3.2. During the analyzed period, for each batch of concrete, the standard deviation is calculated Sm and the coefficient of variation Vm strength. The specified characteristics are calculated for all types of rated strength according to clause 1.2. At the same time, it is allowed not to calculate the coefficient of variation of the strength of concrete at the design age for prefabricated structures, but to take it equal to 85% of the coefficient of variation of the tempering strength.
3.3. When testing samples, the standard deviation of the strength of concrete in the batch ( Sm), MPa, with the number of unit values of concrete strength in the batch P more than six are calculated by the formula
If the number of unit values of concrete strength in a batch is from two to six, the value Sm calculated by the formula
where Wm - the range of unit values of concrete strength in a controlled batch, defined as the difference between the maximum and minimum unit values of strength, MPa;
(- coefficient depending on the number of single values (P) and taken according to the table. one.
Table 1
When testing by non-destructive methods, in the case when the average strength of the concrete of the structure is taken as a unit value, the value St, MPa, calculated taking into account the deviations of the calibration dependence by the formula
where ST - standard deviation of the calibration dependence, determined according to the current state standards for non-destructive methods, MPa;
P - the number of single values (controlled structures) in the batch;
R - the number of controlled areas in the structure. In the case when the strength of concrete in the controlled area is taken as a unit value, the value Sm, MPa, calculated by the formula
where Kn- correction factor determined according to Appendix 2;
P - the number of unit values of concrete strength (controlled areas) in the batch.
3.4. Coefficient of variation of concrete strength in a batch (batch coefficient) ( Vm) as a percentage is calculated by the formula
3.5. The average value of the batch coefficient of variation of concrete strength for the analyzed period (p) in percent is calculated by the formula
where Vm, i - coefficients of variation of concrete strength in each i th of P batches of concrete controlled during the analyzed period, calculated by the formula (6);
ni - the number of unit values of concrete strength in each i th of P batches of concrete controlled during the analyzed period;
- the total number of unit values of concrete strength for the analyzed period (at least 30).
3.6. When controlling the strength of concrete at a construction site, the coefficient of variation of the strength of concrete is taken according to the document on the quality of the concrete mixture of the manufacturer.
3.7. It is allowed for the control of irregularly produced prefabricated structures and concrete mixtures to take the coefficient of variation equal to the coefficient of variation of concrete of a different composition, provided that it is manufactured using the same technology and on the same materials and differing in strength by no more than two classes (grades).
4. DETERMINATION OF THE REQUIRED CONCRETE STRENGTH
4.1. The required strength of concrete (tempering, transfer, at intermediate or design ages) when normalizing strength by classes ( Rt), MPa, calculated by the formula
RT = KT Bnorm, (8)
where Bnorm- standardized value of concrete strength (tempered, transfer, at intermediate or design age) for concrete of a given class in terms of compressive strength, axial tension or bending tension, MPa;
KT- the coefficient of the required strength for all types of concrete, taken in accordance with table. 2 depending on the average coefficient of variation of concrete strength Vn for all parties for the analyzed period, calculated by the formula (7).
When using non-destructive methods for controlling the strength of concrete in cases where the strength of concrete of the controlled section of the structure is taken as a unit value, the right side of formula (8) should be multiplied by a coefficient equal to 0.95.
4.2. The required strength of concrete when normalizing strength by grade is determined in accordance with Appendix 3.
table 2
|
for all types of concrete (except for dense silicate, cellular) and structures, except for massive hydraulic engineering |
|||||
|
Invalid Scope |
|||||
|
values |
|||||
|
21 and more |
|||||
4.3. If necessary, control the strength of the concrete individual. batches the coefficient of the required strength can be taken from table. 2 or the table in Appendix 3, depending on the coefficient of variation of the strength of concrete in a given batch, calculated by the formula (6). Moreover, the number of unit values of concrete strength in this batch must be at least 30.
4.4. In the initial period, before the accumulation of the number of test results required for conducting statistical control, the required concrete strength ( RT) is determined by the formula
where KB- coefficient taken according to table. 3 depending on the type of concrete.
table 3
4.5. The duration of the controlled period during which the specified value of the required strength can be used should be taken from one week to 1 month.
5. RECEPTION OF CONCRETE BY STRENGTH
5.1. Lots of prefabricated concrete are accepted according to the release and transfer strength, and monolithic structures - according to the strength of concrete at the design age.
5.2. A batch of concrete is subject to acceptance if the actual concrete strength in the batch ( Rm) will not be lower than the required strength ( RT), i.e.
Rm(RT(11)
5.3. The control of ensuring the strength of concrete of prefabricated structures at the design age is carried out periodically within the timeframes specified in clause 2.3, by comparing the required strength at the design age with the average strength of concrete at this age of all batches monitored during the week.
The strength of concrete of prefabricated structures at the design age is recognized as meeting the requirements of this standard if the condition of formula (11) is met. At the same time, the test results refer to all batches of concrete made in a week.
In case of violation of this condition, the manufacturer is obliged to inform the consumer about this within three days after the end of all tests.
5.4. The possibility of using batches of structures whose concrete strength does not meet the requirements of paragraphs. 5.2 and 5.3, must be agreed with the design organization.
The same agreement is necessary for the further manufacture and use of structures, if the average batch coefficient of variation for the next controlled period falls into the area of unacceptable values.
5.3, 5.4.(Modified edition, Amendment No. 1).
5.5. The values of the actual and required concrete strength must be indicated in the document on the quality of the batch of prefabricated structures in accordance with GOST 13015.3 or concrete mixture in accordance with GOST 7473 and in the journal of concrete works for monolithic structures.
6. DETERMINATION OF THE AVERAGE LEVEL OF CONCRETE STRENGTH
6.1. Average for the controlled period the level of strength of the tempering, transfer for prefabricated structures, at intermediate and design age for monolithic structures) of concrete ( Ru), MPa, is determined by the formula
Ru = RT Km.p, (12)
where Km.p - coefficient taken according to table. 4 depending on the average coefficient of variation for the analyzed period Vn.
In this case, the value Km.p should be taken for heavy and light concrete no more than 1.10, and for dense silicate concrete - no more than 1.13.
6.2. It is allowed to exceed the actual average concrete strength of prefabricated structures at the design age (
) over the required (
), which is characterized by the coefficient ( Kv) calculated by the formula
The values Kv, calculated by the formula (13), are compared with the values given in the table of Appendix 4.
(Modified edition, Amendment No. 1).
6.3. In cases where the concrete selected by the manufacturer's laboratory based on the conditions for ensuring the design grade for water resistance, frost resistance or other requirements, must have an average strength higher than the average strength level at the design age calculated by formula (12), then as an average level take the strength determined during the selection of the composition.
6.4. The upper warning limit of the average strength of concrete in a controlled batch (
), MPa, the excess of which indicates an overestimation of the actual strength, is calculated by the formula
where V m.p - coefficient of inter-batch variation of strength, taken equal to 0.5 Vn.
6.5. If the strength of concrete is higher in three batches in a row
or the actual average level of strength for the controlled period exceeds the average level of strength calculated by formula (12), or the value of the coefficient Kv, determined by the formula (13), higher than the values given in Appendix 4, then measures should be taken to reduce the strength of concrete and reduce the consumption of cement.
ANNEX 1
Reference
BASIC TERMS, EXPLANATIONS AND SYMBOLS
|
Symbol |
Explanation |
|
|
1.Rated strength of concrete |
The strength value specified in the normative-technical or design documentation (at design and intermediate age, vacation, transfer) |
|
|
2. Required concrete strength |
The minimum permissible value of the actual strength of concrete in a batch, established by the laboratories of enterprises and construction sites in accordance with the achieved uniformity |
|
|
3. Actual strength of concrete in a batch |
The average value of the strength of concrete in a batch, determined from the results of testing control samples or non-destructive methods directly in the structure |
|
|
4. Average level of concrete strength |
The average value of the strength of concrete, established by the laboratories of enterprises and construction sites for a certain controlled period in accordance with the achieved uniformity of concrete in terms of strength, for which its composition is selected and which is maintained in production |
|
|
5. Design age of concrete |
The time of concrete hardening established in the normative-technical or design documentation, during which the strength corresponding to its class or brand must be achieved |
|
|
According to GOST 10180 and GOST 10181.0 |
||
|
7. Sample series |
According to GOST 10180 |
|
|
8. Controlled area |
The section of the structure where measurements are taken during the control of concrete strength by non-destructive methods |
|
|
9. Analyzed period |
The time period over which the batch average strength coefficient of variation is calculated to assign the required strength over a subsequent controlled period |
|
|
10. Controlled period |
The period of time during which the required strength is taken constant in accordance with the coefficient of variation for the previous analyzed period |
|
|
11. Technological complex |
One of several technological lines of the plant, for which the control of the strength of concrete of the same nominal composition, prepared using the same technology and hardened under the same conditions, is performed using one batch coefficient of variation Vn calculated for the analyzed period |
APPENDIX 2
Mandatory
ADDITIONAL REQUIREMENTS FOR CONTROL OF CONCRETE STRENGTH BY NON-DESTRUCTIVE METHODS
1. For a unit value for non-destructive testing, take:
- when inspecting the structures of flat and hollow-core floor slabs and coverings, road slabs, panels of internal load-bearing walls, wall blocks, as well as pressure and non-pressure pipes - the average strength of the concrete structure, calculated as the arithmetic mean of the concrete strength of the controlled sections of the structure;
- in all other cases, including monolithic and precast-monolithic structures, - the average concrete strength of the controlled section of the structure (or part of a monolithic, prefabricated-monolithic structure).
2. The control of concrete strength by non-destructive methods (ultrasonic pulsed or mechanical) in the case when the average strength of concrete of a structure is taken as a unit value is carried out using a calibration dependence previously established in accordance with the requirements of the current state standards for these methods.
3. The control of concrete strength by non-destructive methods in the case when the average concrete strength of the controlled area is taken as a unit value is carried out using a correction factor Kp in formula (5) section. 3, which is determined before starting the transition to these methods with each change in the nominal composition of concrete, construction technology, type of materials used, with each new establishment of the calibration dependence, but at least once a year.
Coefficient Kp calculated by the formula
where Vн.m - coefficient of variation of concrete strength of all series of samples tested by non-destructive method to establish the calibration dependence;
Vo - coefficient of variation of concrete strength of the same series of samples. tested by loading to establish the calibration dependence.
To establish the calibration dependence, the value of the coefficients of variation Vo and Vn.m determined by a formula similar to the formula (7) Sec. 3.
APPENDIX 3
Mandatory
DETERMINATION OF THE REQUIRED STRENGTH OF CONCRETE WHEN RATING IT BY GRADES
1. The required strength of concrete (tempering, transfer, at intermediate or design age) when normalizing strength by grade ( RT), MPa, calculated by the formula
RT = Rnorm
where Rnorm- the normalized value of concrete strength (tempering, transfer,. At intermediate or design age) for concrete of a given grade in terms of compressive strength, axial tension or bending tension, MPa;
K (T - coefficient of required strength in percent for all types of concrete, taken in accordance with the table of this annex, depending on the average batch coefficient of variation of concrete strength Vn for the analyzed period, calculated according to the formula (7) section. 3.
|
for all types of concrete (except for dense silicate cellular concrete) and structures, except for massive hydraulic engineering |
for dense silicate concrete |
for autoclaved aerated concrete |
for massive hydraulic structures |
|||
|
Invalid Scope |
||||||
|
values |
||||||
|
21 and more |
||||||
When using non-destructive methods for controlling the strength of concrete in cases where the strength of concrete of the controlled section of the structure is taken as a unit value, the right-hand side of formula (1) should be multiplied. by a coefficient equal to 0.95.
2. In the initial period before the accumulation of the number of test results required for conducting statistical control, m is determined by the formula
R m = 1.1 ( Rnorm. (2)
3. The duration of the controlled period is taken in accordance with clause 4.5 of this standard.
APPENDIX 4
Reference
VALUE OF COEFFICIENT Kv FOR CONCRETE CONCRETE STRUCTURES
Coefficient values TO c for heavy concrete are given in the table.
|
Class or grade of concrete |
Duration of heat treatment, h |
cement by the efficiency of heat treatment in accordance with GOST |
Normalized tempering strength, as a percentage of the class or grade of concrete |
|||
|
B 15 or M200 and below |
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|
B20, B25 or M250 and M300 |
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|
B30, B35, B40 or M350, M400, M450 and M500 |
||||||
|
Note... With a coefficient Kv more than 1.00, technological measures should be applied (lengthen the heat treatment cycle, use additives that accelerate concrete hardening or use more effective cements, etc.) aimed at increasing the strength of concrete after heat treatment and reducing cement consumption. 2. For lightweight concrete of classes B7.5 (grades M100) and less, the value Kv taken equal to 1. For lightweight concrete of classes B10 (grades M150) and more, the value Kv taken according to the table for heavy concrete multiplied by a factor of 0.85 when using porous aggregates with a strength grade less than the concrete grade. In this case, the value Kv in all cases should not be less than 1. |
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INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Scientific Research Institute of Concrete and Reinforced Concrete (NIIZhB) of the USSR State Construction Committee
DEVELOPERS
M.I.Brusser, Cand. tech. Sciences (topic leader); V. A. Dorf, Cand. tech. sciences; A. G. Malinovsky, V. V. Tishenko, I. N. Nagornyak
2. APPROVED AND PUT INTO EFFECT by the Decree of the State Committee of the USSR for Construction Affairs dated 13.08.86 No. 108
3. REPLACE GOST 18105.0 - 80, GOST 18105.1-80, GOST 18105.2 - 80 and GOST 13015 - 75 in terms of tensile strength control
4. REFERENCE REGULATORY AND TECHNICAL DOCUMENTS
5. REPUBLICATION (May 1992) with Amendment No. 1, approved in December 1987 (IUS 4 - 88)
interstate council for standardization, metrology and certification
(IGU)
INTERSTATE COUNCIL FOR STANDARDIZATION, METROLOGY AND CERTIFICATION
Foreword
The goals, basic principles and basic procedure for work on interstate standardization are established by GOST 1.0-92 “Interstate standardization system. Basic Provisions "and MSN 1.01-01-2009" System of Interstate Regulatory Documents in Construction. Basic provisions "
Information about the standard
1 DEVELOPED by the Research, Design and Technological Institute of Concrete and Reinforced Concrete (NIIZhB - a branch of the Federal State Unitary Enterprise "Research Center Construction")
2 INTRODUCED by the Technical Committee for Standardization TC 465 "Construction"
3 ACCEPTED by the Interstate Scientific and Technical Commission for Standardization, Technical Regulation and Certification in Construction (Appendix D to Protocol No. 37 of October 7, 2010)
| Short name of the country according to MK (ISO 3166) 004-97 | MK country code (ISO 3166) 004-97 | Abbreviated name of the national authority government controlled construction |
| Azerbaijan | Gosstroy |
|
| Ministry of Urban Development |
||
| Kazakhstan | Agency for Construction and Housing and Communal Services |
|
| Kyrgyzstan | Gosstroy |
|
| Ministry of Construction and Regional Development |
||
| the Russian Federation | Department of Urban Development Regulation of the Ministry of Regional Development |
|
| Tajikistan | Agency for Construction and Architecture under the Government |
|
| Uzbekistan | Gosarkhitektstroy |
|
| Ministry of Regional Development and Construction |
4 This standard takes into account the main provisions European standard EN 206-1: 2000 "Concrete - Part 1: General technical requirements, performance characteristics, production and conformity criteria "(EN 206-1: 2000" Concrete - Part 1: Specification, performance, production and conformity ") in terms of control and assessment of concrete strength.
Degree of Compliance - Non-Equivalent (NEQ)
5 By order of the Federal Agency for Technical Regulation and Metrology dated March 21, 2012 No. 28-st, the interstate standard GOST 18105-2010 was put into effect as a national standard Russian Federation from September 1, 2012
6 REPLACE GOST 18105-86 *
* In the Russian Federation, GOST R 53231-2008 is in force until September 1, 2012.
7 REDISSION. January 2013
Information O administered v action (termination actions) the present standard and changes To him published v pointer "National standards ".
Information about changes To the present standard published v pointer (catalog) "National standards ", a text changes - v information signposts "National standards ". V case revision or canceling the present standard the corresponding information will published v information pointer "National standards "
GOST 18105-2010
INTERSTATE STANDARD
CONCRETE
Rules for the control and assessment of strength
Concretes. Rules for control and assessment of strength
Date of introduction - 2012-09-01
1 area of use
This standard applies to all types of concretes for which the strength is standardized, and establishes the rules for monitoring and assessing the strength of a ready-to-use concrete mixture (hereinafter - BSG), concrete of monolithic, precast-monolithic and precast concrete and reinforced concrete structures during production control of concrete strength. ...
The rules of this standard can be used when conducting surveys of concrete and reinforced concrete structures, as well as in the expert assessment of the quality of concrete and reinforced concrete structures.
Compliance with the requirements of this standard ensures that the design and regulatory resistance concrete structures.
GOST 7473-2010 Concrete mixtures. Technical conditions
GOST 10180-90 Concrete. Methods for determining the strength of control samples
GOST 13015-2003 Reinforced concrete and concrete products for construction. General technical requirements. Rules for acceptance, labeling, transportation and storage
GOST 17624-87 Concrete. Ultrasonic method for determining strength
GOST 22690-88 Concrete. Determination of strength mechanical methods non-destructive testing
GOST 27006-86 Concrete. Squad selection rules
GOST 28570-90 Concrete. Methods for determining strength by samples taken from structures
Note - When using this standard, it is advisable to check the operation of the reference standards in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet or according to the annually published information index " National standards", Which is published as of January 1 of the current year, and according to the corresponding monthly published information signs published in 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 not affecting this reference.
3 Terms, definitions and symbols
3.1 Terms and definitions
The following terms are used in this standard with the corresponding definitions:
1 rated strength of concrete: The strength of concrete at the design age or its proportion at the intermediate age, established in the standard or technical document, according to which the BSG or structure is made.
Note - Depending on the type of strength at the design age, the following concrete strength classes are established:
V- compressive strength class of concrete;
B t- axial tensile strength class of concrete;
B tb- class of concrete for tensile strength in bending.
3.1.2 required concrete strength: The minimum permissible average value of concrete strength in controlled batches of BSG or structures, corresponding to the rated strength of concrete with its actual homogeneity.
3.1.3 actual concrete strength class: The value of the class of concrete for the strength of monolithic structures, calculated based on the results of determining the actual strength of concrete and its homogeneity in the controlled batch.
3.1.4 actual concrete strength: Average value of concrete strength in batches of BSG or structures, calculated from the results of its determination in a controlled batch.
3.1.5 concrete sample: The volume of BSG of one nominal composition, from which one or several series of control samples are simultaneously made.
3.1.6 series of control samples: Several samples made from one sample of BSG or taken from one structure, hardened under the same conditions and tested at the same age to determine the actual strength of one type.
3.1.7 batch of concrete mix: The volume of BSG of one nominal composition, made or laid in a certain time.
3.1.8 batch of monolithic structures: Part of a monolithic structure, one or more monolithic structures made in a certain time.
3.1.9 batch of prefabricated structures: Structures of the same type, sequentially manufactured using the same technology for no more than one day from materials of the same type.
3.1.10 controlled section of the structure: The part of the structure on which the unit value of concrete strength is determined by non-destructive methods.
3.1.11 construction area: A part of a controlled structure, the strength of concrete of which differs from the average strength of this structure by more than 15%.
3.1.12 analyzed period: The period of time over which the average value of the coefficient of variation of the strength of concrete is calculated for batches of BSG or structures manufactured during this period.
3.1.13 current coefficient of variation of concrete strength: The coefficient of variation of the strength of concrete in a controlled batch of BSG or structures.
3.1.14 average coefficient of variation of concrete strength: The average value of the coefficient of variation of concrete strength for the analyzed period when controlled according to schemes A and B.
3.1.15 sliding coefficient of variation of concrete strength: The coefficient of variation of concrete strength, calculated as the average for the current batch and previous controlled batches of BSG or structures when controlled according to scheme B.
3.1.16 controlled period: The period of time during which the required concrete strength is assumed constant in accordance with the coefficient of variation for the previous analyzed period.
3.1.17 current control: Control of the concrete strength of a batch of BSG or structures, in which the values of the actual strength and homogeneity of concrete in terms of strength (current coefficient of variation) are calculated based on the control results of this batch.
3.1.18 destructive methods for determining the strength of concrete: Determination of the strength of concrete according to control samples made from a concrete mixture in accordance with GOST 10180 or selected from structures in accordance with GOST 28570.
3.1.19 direct non-destructive methods for determining the strength of concrete: Determination of concrete strength by “shearing off with shearing” and “shearing off the rib” in accordance with GOST 22690.
3.1.20 indirect non-destructive methods for determining the strength of concrete: Determination of concrete strength according to pre-established calibration relationships between concrete strength, determined by one of the destructive or direct non-destructive methods, and indirect strength characteristics, determined in accordance with GOST 22690 and GOST 17624.
3.1.21capture: The volume of concrete of a monolithic structure or part of it, laid during continuous concreting of one or several batches of BSG for a certain time.
3.1.22 unit strength value: The value of the actual strength of concrete of the standardized type, taken into account when calculating the characteristics of the homogeneity of concrete:
For BSG - the average value of the concrete strength of the concrete mixture sample;
For prefabricated structures - the average value of the concrete strength of a concrete mixture sample or the average value of the concrete strength of a section of the structure, or the average value of the concrete strength of one structure;
For monolithic structures - the average value of the strength of the concrete of a section of the structure or concrete of one structure.
3.2 Symbols
V norms - design class of concrete strength, MPa;
V f is the actual strength class of concrete, MPa;
R i,, - single, minimal and maximum value concrete strength in a batch, MPa;
R m- actual average concrete strength of a separate batch, MPa;
R T, is the required average strength of concrete BSG or a structure in a controlled batch or in a controlled period, MPa;
S m- standard deviation of concrete strength in the controlled batch, MPa;
S H. M is the standard deviation of concrete strength in the controlled batch according to the results of its determination by non-destructive methods, MPa;
S T is the calculated standard deviation of the used calibration dependence, MPa;
S T. H. M is the standard deviation of the constructed calibration dependence, MPa;
S T. P. M is the standard deviation of destructive or direct non-destructive methods used to construct the calibration dependence, MPa;
V m- current coefficient of variation of concrete strength in the batch,%;
Average coefficient of variation of concrete strength for the analyzed period,%;
V c- sliding coefficient of variation of concrete strength for the analyzed period,%;
W m- the range of concrete strength in the batch, MPa;
P- the number of unit values of concrete strength in the batch;
a - coefficient for calculation S m(at P£ 6);
r- correlation coefficient of the calibration dependence;
K T is the coefficient of the required strength;
t a - coefficient for calculation K T and V f;
t b - coefficient for calculation K T and V f.
4 Key points
4.1 Control and assessment of the strength of concrete at enterprises and organizations producing BSG, prefabricated, precast-monolithic and monolithic concrete and reinforced concrete structures, should be carried out by statistical methods, taking into account the characteristics of the homogeneity of concrete in terms of strength.
Acceptance of concrete by comparing its actual strength with the required one, without taking into account the characteristics of concrete strength homogeneity, is not allowed.
4.2 All types of rated strength are subject to control:
Strength at design age - for BSG, prefabricated, prefabricated monolithic and monolithic structures;
Release and transfer strength - for prefabricated structures;
Strength at an intermediate age - for BSG and monolithic structures (when removing the load-bearing formwork, loading structures until they reach their design strength, etc.).
In the event that the normalized tempering or transfer strength of concrete of prefabricated structures or the strength of concrete at an intermediate age for BSG or monolithic structures is 90% or more of the value of the design class, the strength control at the design age is not carried out.
4.3 The control of concrete strength for each type of rated strength specified in 4.2 is carried out according to one of the following schemes:
Scheme A - determination of the characteristics of the homogeneity of concrete in terms of strength, when at least 30 single results of determining the strength obtained by monitoring the strength of concrete of previous batches of BSG or prefabricated structures in the analyzed period are used;
Scheme B - determination of the characteristics of the homogeneity of concrete in terms of strength, when at least 15 single results of determining the strength of concrete in a controlled batch of BSG or prefabricated structures and previous controlled batches in the analyzed period are used;
Scheme B - determination of the characteristics of the homogeneity of concrete in terms of strength, when the results of non-destructive testing of concrete strength of one current controlled batch of structures are used, while the number of unit values of concrete strength must comply with the requirements of 5.8;
Scheme D - without determining the characteristics of the homogeneity of concrete in terms of strength, when during the manufacture of individual structures or in the initial period of production it is impossible to obtain the number of results for determining the strength of concrete provided for in schemes A and B, or when conducting non-destructive testing of concrete strength without construction calibration dependencies, but using universal dependencies by linking them to the concrete strength of a controlled batch of structures.
Note - In exceptional cases (if it is impossible to carry out continuous testing of the strength of concrete of monolithic structures using non-destructive methods), it is allowed to determine the strength of concrete by control samples made at the construction site and hardened in accordance with the requirements of 5.4, or by control samples taken from the structures. In this case, the actual strength class of concrete in a batch of structures at P³ 15 is calculated by the formula (11), at P < 15 - по формуле (13).
4.4 Concrete strength control is carried out:
For BSG - according to schemes A, B, D;
For prefabricated structures - according to schemes A, B, C, D;
For monolithic structures - according to schemes B, G.
4.5 As characteristics of concrete strength homogeneity used to determine the required concrete strength R T or actual class of concrete V f, the coefficients of variation of the concrete strength are calculated:
Average - for all batches of BSG and prefabricated structures for the analyzed period - when controlled according to scheme A;
Sliding V c- average for the controlled and the last previous batches - when controlled according to scheme B;
Current V m- for the current batch of BSG and structures - when controlled according to scheme B.
4.6 When monitoring and assessing the strength of BSG concrete at the manufacturer:
According to scheme A:
R m V m in each batch made during the analyzed period,
calculate the average coefficient of variation of concrete strength for the analyzed period,
R T for the next controlled period,
assess the strength of concrete for each batch made in the controlled period according to 8.2;
According to scheme B:
determine the actual strength of concrete R m in a controlled party,
the characteristics of the homogeneity of concrete in terms of strength are calculated: the current coefficient of variation of the strength of concrete V m V c,
determine the required concrete strength R T in a controlled lot,
According to the scheme D:
determine the actual strength of concrete R m in each batch made in the controlled period,
determine the required concrete strength according to 7.1 R T,
4.7 When monitoring and assessing the strength of concrete in prefabricated structures:
According to scheme A:
determine the actual strength of concrete R m in each batch of structures manufactured in the analyzed period,
V m in each batch and the average coefficient of variation of strength for the analyzed period,
determine the required concrete strength according to 7.1 R T for the next controlled period according to the characteristics of the homogeneity of concrete strength for the analyzed period,
assess the strength of concrete in accordance with 8.2 for each batch of structures manufactured in the controlled period;
According to scheme B:
determine the actual strength of concrete R m in a controlled party,
calculate the characteristics of the homogeneity of concrete in terms of strength - the current coefficient of variation of the strength of concrete V m and the sliding coefficient of variation of concrete strength V c in a controlled party,
determine the required concrete strength according to 7.1 R T in a controlled lot,
assess the strength of concrete in the current controlled batch according to 8.2;
According to scheme B:
determine the actual strength of concrete R m in a controlled party,
V m in a controlled party,
determine the required concrete strength according to 7.1 R T for the controlled lot,
assess the strength of concrete in a controlled batch according to 8.2;
According to the scheme D:
determine the actual strength of concrete R m in a controlled party,
determine the required concrete strength according to 7.1 R T,
assess the strength of concrete in a controlled batch according to 8.2.
4.8 When monitoring and assessing the strength of concrete in batches of monolithic structures:
According to scheme B:
determine by non-destructive methods the actual strength of concrete R m in a controlled party,
calculate the current coefficient of variation of concrete strength V m in a controlled batch, taking into account the error of the applied non-destructive methods when determining the strength according to 6.5,
determine according to 7.3 and 7.4 the actual strength class of concrete V f,
assess the actual concrete strength class in accordance with 8.3 in the controlled batch;
According to the scheme D:
determine by non-destructive or destructive methods (in exceptional cases - see 4.3) the actual strength of concrete R m in a controlled party,
determined by 7.5 the actual strength class of concrete V f in a controlled batch,
carry out according to 8.3 assessment of the strength of concrete in a controlled batch.
5 Determination of the strength of concrete
5.1 The composition of a batch of BSG should include BSG of one nominal composition in accordance with GOST 27006, prepared using the same technology.
The composition of a batch of prefabricated or monolithic structures includes structures made from a concrete mixture of the same nominal composition, molded using the same technology.
The duration of the manufacture of a batch of BSG or structures should be:
At least one shift - for BSG and prefabricated structures and one day - for monolithic structures;
No more than one month - for BSG and one week - for prefabricated and monolithic structures.
It is allowed, during control according to schemes A and B, to combine into one batch of BSG of different nominal composition and one class of concrete in terms of strength, if the following conditions are met:
The maximum of the average values of the coefficient of variation of the strength of the concretes of the combined compositions for the analyzed period does not exceed 13%;
The difference between the maximum and minimum values of the coefficient of variation of the strength of the concrete of the combined compositions for the analyzed period does not exceed 2%;
The largest aggregate size in the combined compositions differs by no more than two times, and the cement consumption in these compositions is no more than 10% of the average value.
The conditions for combining concrete compositions are checked once a year according to the results of determining the characteristics of the homogeneity of concrete in terms of strength separately for each nominal composition for the last two controlled periods.
When combined in one batch of BSG of different compositions, the value of the coefficient of variation of the strength of concrete in the first controlled period is determined as the arithmetic mean of the coefficients of variation for individual nominal compositions.
5.2 When determining the strength of concrete according to control samples, at least two BSG samples are taken from each batch and at least one sample:
per shift - at the factory - manufacturer of prefabricated structures;
per day - at the enterprise - the manufacturer of BSG and the construction site in the manufacture of monolithic structures.
In exceptional cases (see 4.3), when determining the strength of concrete of monolithic structures using control samples, the number of concrete samples taken from each batch of the structure must be at least six.
5.3 From each sample of the concrete mix, a series of control samples is made to determine each type of rated strength specified in 4.2.
The number of samples in a batch is taken in accordance with GOST 10180.
It is allowed to make a series of control samples for determining the strength of concrete of prefabricated structures at the design age, not from each sample, but from at least two samples taken from one batch per week with a concrete strength class of B30 and below, and four samples taken from two batches. per week for concrete strength class B35 and higher.
When controlling the strength of aerated concrete from the finished structures of each batch or from blocks made simultaneously with the structures, concrete samples are cut out or drilled out in at least two sections.
5.4 Test specimens of concrete of prefabricated structures must be hardened in the same conditions as the structures before determining the tempering or transfer strength. Subsequent hardening of samples intended to determine the strength of concrete at the design age should take place under normal conditions at a temperature of (20 ± 3) ° С and a relative humidity of (95 ± 5)%.
Control samples from BSG, intended for the manufacture of monolithic structures, must harden at the enterprise - the manufacturer of the concrete mixture under normal conditions.
Control samples made at the construction site during the incoming control of the concrete strength of BSG batches must harden under normal conditions.
Control samples made at a construction site for monitoring and assessing the strength of concrete in batches of monolithic structures in accordance with 4.3 must harden in the conditions provided for by the project for the production of work or technological regulations for the production of monolithic concrete and reinforced concrete structures of this construction object.
5.5 Concrete strength control by indirect non-destructive methods is carried out with the obligatory use of calibration dependencies previously established in accordance with the requirements of GOST 22690 and GOST 17624.
5.6 When controlling the tempering and transfer strength of concrete of prefabricated structures by non-destructive methods, the number of controlled structures of each type is taken to be at least 10% or at least 12 structures from a batch. If a batch consists of 12 structures or less, a continuous inspection is carried out. In this case, the number of controlled sections must be at least one per 4 m of the length of linear structures and at least one per 4 m 2 of the area of flat structures.
5.7 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.
5.8 When testing the strength of concrete of monolithic structures at design age by non-destructive methods, continuous non-destructive testing of the strength of concrete of all structures of the controlled batch is carried out. In this case, the number of controlled areas must be at least:
Three for each grip - for flat structures (walls, floors, foundation slabs);
One for 4 m in length (or three per grip) - for each line horizontal structure(beam, crossbar);
Six 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.
The number of measurements carried out at each controlled area is taken in accordance with GOST 17624 or GOST 22690.
Note - When conducting surveys and expert assessment of the quality of linear vertical structures, the number of controlled areas should be at least four.
5.9 Actual strength of concrete in a batch R m
where R i- unit value of concrete strength, MPa;
P- the total number of unit values of concrete strength in the batch.
The unit value of concrete strength is taken as follows:
When testing by samples - the average strength of a series of samples made from one sample of BSG, to control one type of normalized strength specified in 4.2;
When inspected by non-destructive methods - the average strength of concrete in the controlled area or structure zone or the average strength of concrete separate design.
The rule for choosing a unit value of concrete strength when using non-destructive methods, depending on the type of structures, is given in Appendix A.
5.10 The strength of concrete is determined by the test results of samples in accordance with GOST 10180 and GOST 28570 or by non-destructive methods in accordance with GOST 17624 and GOST 22690.
The strength of concrete of prefabricated structures at the design age and the tensile strength of concrete are determined only by reference samples.
6 Determination of the characteristics of the homogeneity of concrete in terms of strength
6.1 The duration of the analyzed period for determining the characteristics of the homogeneity of concrete in terms of strength according to schemes A and B is set from one week to three months.
The number of unit values of concrete strength during this period, depending on the selected control scheme, is taken according to 4.3.
6.2 For each batch of BSG or structures, calculate the standard deviation S m and the current coefficient of variation of concrete strength V m... The specified characteristics are calculated for all types of rated strength specified in 4.2.
It is allowed not to calculate the coefficient of variation of concrete strength at the design age for prefabricated structures, but to take it equal to 85% of the coefficient of variation of the tempering strength.
6.3 Standard deviation of concrete strength in a batch S m, MPa, calculated by the formula
6.4 When the number of unit values of concrete strength in a batch is from two to six, the value of the standard deviation S m it is allowed to calculate by the formula
Coefficient a is taken according to table 1.
Table 1 - Coefficient a
6.5 When testing the strength of concrete by non-destructive methods, if the strength of a site, a zone or a separate structure is taken as a unit value, the standard deviation S m the strength of concrete in a batch is calculated by the formula
where S T is determined by the formula
where S T. P. M is taken equal to:
For the method of separation with spalling - 0.04 of the average concrete strength of the areas used in the construction of the calibration dependence for an anchor device with an embedment depth of 48 mm; 0.05 medium strength - at a depth of 35 mm; 0.06 medium strength - at a depth of 30 mm; 0.07 medium strength - at a depth of 20 mm;
For destructive methods - 0.02 of the average strength of the tested samples.
Meaning r is determined when constructing a calibration dependence according to the formula (6). Meaning r should be at least 0.7.
where R i f and R iH- values of concrete strength of sections (or series of samples), determined by destructive and non-destructive methods when establishing the calibration dependence.
6.6 Current coefficient of variation of concrete strength V m in a batch of BSG or structures is determined by the formula
6.7 When controlled according to scheme A, the average value of the coefficient of variation of concrete strength, and when controlled according to scheme B - the sliding coefficient of variation of concrete strength for the analyzed period V c calculated by the formula
where are the coefficients of variation of the concrete strength in each i th party;
n i- the number of unit values of concrete strength in each i th party;
The total number of unit values of concrete strength for the analyzed period.
When controlled according to scheme B, the current coefficient of variation of concrete strength V m in the controlled lot is calculated by the formula (7).
6.8 When controlling irregularly produced lots of BSG and prefabricated structures, it is allowed to take the coefficient of variation of the strength of concrete equal to the coefficient of variation of the strength of concrete made from BSG of a different composition, provided it is manufactured using the same technology, from the same materials and differing in strength by no more than two classes.
7 Determination of the required strength and the actual strength class of concrete
7.1 Required strength of each concrete type R T for BSG and prefabricated structures, MPa, is calculated by the formula
R T = K T × B norm. (9)
When controlled according to schemes A and B, the coefficient K T is taken according to Table 2, depending on the average coefficient of variation of the strength of concrete for the analyzed period or the current coefficient of variation of the strength of concrete of the controlled batch V m; when controlled according to scheme B coefficient K T calculated by the formula
where the coefficient t a is taken according to Table 3, depending on the total number of unit values of concrete strength in the controlled batches of BSG or structures, according to which the sliding coefficient of variation of strength is calculated V c.
When controlled according to the G scheme, the coefficient K T is taken according to table 4.
Table 2 - Coefficient of required strength K T when testing strength according to schemes A and B
| Average coefficient of variation of strength,% | Required strength coefficient K T for |
|||
| all types of concrete (except for dense silicate and cellular) and structures (except for massive hydraulic structures) | dense silicate concrete | aerated concrete | concrete of massive hydraulic structures |
|
| Invalid range | ||||
Table 3 - Coefficient t a
Table 4 - Coefficient of required strength K T when controlled according to the scheme G
7.2 When controlling according to scheme A, the duration of the controlled period during which the value of the required strength determined in the analyzed period can be used should be taken from one week to one month.
7.3 Actual strength class of concrete for monolithic structures V
Coefficient value K T is taken according to table 2.
7.4 The actual strength class of concrete for individual vertical monolithic structures V when controlled according to scheme B is calculated by the formula
where t b - coefficient taken according to table 5 depending on the number of unit values P.
Table 5 - Coefficient t b
7.5 Actual strength class of concrete for monolithic structures V under control according to scheme D is taken equal to 80% of the average strength of concrete of structures, but not more than the minimum particular value of the strength of concrete of a separate structure or a section of a structure included in the controlled batch:
V f = 0.8 R m. (13)
8 Acceptance of concrete by strength
8.1 Acceptance of lots of BSG and structures is carried out:
In terms of strength at intermediate and design age - for BSG and monolithic structures;
According to the release, transfer and design strength - for prefabricated concrete.
8.2 A batch of BSG and a batch of prefabricated structures are subject to acceptance for the strength of concrete, if the actual strength of concrete in the batch R m not less than the required strength R T, and the minimum unit strength value is not less than the value ( R T - 4) and no less than the standardized strength class of concrete.
R m ³ R T, (14)
B(B t, B tb) < ³ (R T - 4). (15)
8.3 A batch of monolithic structures is subject to acceptance for the strength of concrete, if the actual concrete strength class V f in each individual structure of this batch is not lower than the design class of concrete in terms of strength V norms:
B f ³ B norm. (sixteen)
8.4 The control of the concrete strength of prefabricated structures at the design age is carried out periodically according to 5.3 by comparing the required concrete strength at the design age with the average concrete strength at this age of all batches controlled for a week.
The strength of concrete of prefabricated structures at the design age is recognized as meeting the requirements if the conditions of 8.2 are met. The test results apply to all batches of concrete produced in a week.
In case of violation of these conditions, the manufacturer is obliged to inform the consumer about this within three days after the end of all tests.
8.5 The possibility of using (or the need to strengthen) batches of structures, the actual strength or the actual concrete strength class of which does not meet the requirements of 8.2 - 8.4, must be agreed with the design organization of the construction object.
8.6 The values of the required strength of concrete BSG and prefabricated structures must be indicated in the document on the quality of BSG batches in accordance with GOST 7473 and prefabricated structures - in accordance with GOST 13015.
8.7 The values of the actual strength class of concrete of each monolithic structure should be given in the document on the results of the current control or the document on the results of the survey.
Appendix A
(required)
Selection of a unit value for concrete strength under non-destructive testing
For a unit value of concrete strength during non-destructive testing, the following is taken:
When inspecting prefabricated structures (flat and hollow-core slabs and coverings, road slabs, panels of internal load-bearing walls, wall blocks, as well as pressure and non-pressure pipes) - the average strength of the concrete structure, calculated as the arithmetic mean of the concrete strength of the controlled sections of the structure;
When inspecting other types of structures, the average strength of the concrete of the structure or of the controlled area or zone of the structure, or of a part of a monolithic and prefabricated monolithic structure.
Keywords: concrete, rules for monitoring and assessing strength, uniformity of concrete in terms of strength, acceptance of concrete in terms of strength
GOST 18105-2010
INTERSTATE STANDARD
CONCRETE
Rules for the control and assessment of strength
Concretes. Rules for control and assessment of strength
Comparison text of GOST 18105-2010 s GOST R 53231-2008 see on link ;
Text of Comparison of GOST 18105-2018 with GOST 18105-2010 see. link.
- Note from the manufacturer of the database.
____________________________________________________________________
ISS 91.100.30
Introduction date 2012-09-01
Foreword
Foreword
The goals, basic principles and basic procedure for work on interstate standardization are established in GOST 1.0-2015"Interstate standardization system. Basic provisions" and MSN 1.01-01-2009 * "System of interstate regulatory documents in construction. Basic provisions"
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* Document not included. For more information, contact link
Information about the standard
1 DEVELOPED by the Research, Design and Technological Institute of Concrete and Reinforced Concrete (NIIZhB - a branch of the Federal State Unitary Enterprise "Research Center Construction")
2 INTRODUCED by the Technical Committee for Standardization TC 465 "Construction"
3 ACCEPTED by the Interstate Scientific and Technical Commission for Standardization, Technical Regulation and Certification in Construction (Appendix D to Protocol No. 37 of October 7, 2010)
Voted for the adoption of the standard:
Country short name by MK (ISO 3166) 004-97 | Abbreviated name of the national government building authority |
|
Azerbaijan | Gosstroy |
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Armenia | Ministry of Urban Development |
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Kazakhstan | Agency for Construction and Housing and Communal Services |
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Kyrgyzstan | Gosstroy |
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Moldova | Ministry of Construction and Regional Development |
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Russia | Department of Urban Development Regulation of the Ministry of Regional Development |
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Tajikistan | Agency for Construction and Architecture under the Government |
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Uzbekistan | Gosarkhitektstroy |
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Ukraine | Ministry of Regional Development and Construction |
4 By order of the Federal Agency for Technical Regulation and Metrology dated March 21, 2012 N 28-st the interstate standard GOST 18105-2010 was put into effect as a national standard of the Russian Federation on September 1, 2012.
5 This standard takes into account the main provisions of the European standard EN 206-1: 2000 * "Concrete - Part 1. General technical requirements, performance, production and conformity criteria" (EN 206-1: 2000 "Concrete - Part 1: Specification, performance, production and conformity ", NEQ) in terms of control and assessment of concrete strength
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* Access to international and foreign documents can be obtained by clicking on link... - Note from the manufacturer of the database.
6 REPLACE GOST 18105-86
7 REDISSION. August 2018
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 (www.gost.ru)
1 area of use
This standard applies to all types of concretes for which the strength is standardized, and establishes the rules for monitoring and assessing the strength of a ready-to-use concrete mixture (hereinafter - BSG), concrete of monolithic, precast-monolithic and precast concrete and reinforced concrete structures during production control of concrete strength. ...
The rules of this standard can be used when conducting surveys of concrete and reinforced concrete structures, as well as in the expert assessment of the quality of concrete and reinforced concrete structures.
Fulfillment of the requirements of this standard guarantees the provision of the design and standard resistances of concrete structures adopted in the design.
2 Normative references
In this standard, references are made to the following standards:
GOST 7473-2010 Concrete mixes. Technical conditions
GOST 10180-90 Concrete. Methods for determining the strength of control samples
GOST 13015-2003 Reinforced concrete and concrete products for construction. General technical requirements. Rules for acceptance, labeling, transportation and storage
GOST 17624-87 Concrete. Ultrasonic method for determining strength
GOST 22690-88 Concrete. Determination of strength by mechanical methods of non-destructive testing
GOST 27006-86 Concrete. Squad selection rules
GOST 28570-90 Concrete. Methods for determining strength by samples taken from structures
Note - When using this standard, it is advisable to check the validity of reference standards in the public information system - on 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 for the issues of the monthly information index "National Standards" for this 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 not affecting this reference.
3 Terms, definitions and symbols
3.1 Terms and definitions
The following terms are used in this standard with the corresponding definitions:
3.1.1 normalized concrete strength: The strength of concrete at the design age or its share at the intermediate age, established in the normative or technical document, according to which the BSG or the structure is made.
Note - Depending on the type of strength at the design age, the following concrete strength classes are established:
- compressive strength class of concrete;
- axial tensile strength class of concrete;
- class of concrete for tensile strength in bending.
3.1.2 required concrete strength: The minimum permissible average value of concrete strength in controlled batches of BSG or structures, corresponding to the rated strength of concrete with its actual homogeneity.
3.1.3 actual concrete strength class: The value of the class of concrete for the strength of monolithic structures, calculated based on the results of determining the actual strength of concrete and its homogeneity in the controlled batch.
3.1.4 actual concrete strength: Average value of concrete strength in batches of BSG or structures, calculated from the results of its determination in a controlled batch.
3.1.5 concrete sample: The volume of BSG of one nominal composition, from which one or several series of control samples are simultaneously made.
3.1.6 series of control samples: Several samples made from one sample of BSG or taken from one structure, hardened under the same conditions and tested at the same age to determine the actual strength of one type.
3.1.7 batch of concrete mix: The volume of BSG of one nominal composition, made or laid in a certain time.
3.1.8 batch of monolithic structures: Part of a monolithic structure, one or more monolithic structures made in a certain time.
3.1.9 batch of prefabricated structures: Structures of the same type, sequentially manufactured using the same technology for no more than one day from materials of the same type.
3.1.10 controlled section of the structure: The part of the structure on which the unit value of concrete strength is determined by non-destructive methods.
3.1.11 construction area: A part of a controlled structure, the strength of concrete of which differs from the average strength of this structure by more than 15%.
3.1.12 analyzed period: The period of time over which the average value of the coefficient of variation of the strength of concrete is calculated for batches of BSG or structures manufactured during this period.
3.1.13 current coefficient of variation of concrete strength: The coefficient of variation of the strength of concrete in a controlled batch of BSG or structures.
3.1.14 average coefficient of variation of concrete strength: The average value of the coefficient of variation of concrete strength for the analyzed period when controlled according to schemes A and B.
3.1.15 sliding coefficient of variation of concrete strength: The coefficient of variation of concrete strength, calculated as the average for the current batch and previous controlled batches of BSG or structures when controlled according to scheme B.
3.1.16 controlled period: The period of time during which the required concrete strength is assumed constant in accordance with the coefficient of variation for the previous analyzed period.
3.1.17 current control: Control of the concrete strength of a batch of BSG or structures, in which the values of the actual strength and homogeneity of concrete in terms of strength (current coefficient of variation) are calculated based on the control results of this batch.
3.1.18 destructive methods for determining the strength of concrete: Determination of the strength of concrete according to control samples made from a concrete mixture according to GOST 10180 or selected from designs by GOST 28570.
3.1.19 direct non-destructive methods for determining the strength of concrete: Determination of the strength of concrete by "shearing off with shearing" and "shearing off the rib" by GOST 22690.
3.1.20 indirect non-destructive methods for determining the strength of concrete: Determination of the strength of concrete according to pre-established calibration dependencies between the strength of concrete, determined by one of the destructive or direct non-destructive methods, and indirect strength characteristics, determined by GOST 22690 and GOST 17624.
3.1.21 capture: The volume of concrete of a monolithic structure or part of it, laid during continuous concreting of one or several batches of BSG for a certain time.
3.1.22 unit strength value: The value of the actual strength of concrete of the standardized type, taken into account when calculating the characteristics of the homogeneity of concrete:
- for BSG - the average value of the concrete strength of the concrete mixture sample;
- for prefabricated structures - the average value of the concrete strength of a concrete mixture sample or the average value of the concrete strength of a section of the structure, or the average value of the concrete strength of one structure;
- for monolithic structures - the average value of the strength of the concrete of a section of the structure or concrete of one structure.
3.2 Symbols
Design class of concrete strength, MPa;
- actual class of concrete strength, MPa;
,, - single, minimum and maximum values of concrete strength in a batch, MPa;
- actual average concrete strength of a separate batch, MPa;
, is the required average strength of concrete BSG or a structure in a controlled batch or in a controlled period, MPa;
- standard deviation of concrete strength in the controlled batch, MPa;
- standard deviation of concrete strength in a controlled batch according to the results of its determination by non-destructive methods, MPa;
- calculated standard deviation of the used calibration dependence, MPa;
- standard deviation of the built calibration dependence, MPa;
- standard deviation of destructive or direct non-destructive methods used in the construction of the calibration dependence, MPa;
- current coefficient of variation of concrete strength in the batch,%;
- average coefficient of variation of concrete strength for the analyzed period,%;
- sliding coefficient of variation of concrete strength for the analyzed period,%;
- the range of concrete strength in the batch, MPa;
- the number of unit values of concrete strength in the batch;
- coefficient for calculation (at 6);
- correlation coefficient of the calibration dependence;
- coefficient of required strength;
- coefficient for calculating and;
- coefficient for calculating and.
4 Key points
4.1 Control and assessment of the strength of concrete at enterprises and organizations producing BSG, prefabricated, precast-monolithic and monolithic concrete and reinforced concrete structures, should be carried out by statistical methods, taking into account the characteristics of the homogeneity of concrete in terms of strength.
Acceptance of concrete by comparing its actual strength with the required one, without taking into account the characteristics of concrete strength homogeneity, is not allowed.
4.2 All types of rated strength are subject to control:
- strength at design age - for BSG, prefabricated, prefabricated monolithic and monolithic structures;
- Tempering and transfer strength - for prefabricated structures;
- strength at an intermediate age - for BSG and monolithic structures (when removing the load-bearing formwork, loading structures until they reach their design strength, etc.).
In the event that the normalized tempering or transfer strength of concrete of prefabricated structures or the strength of concrete at an intermediate age for BSG or monolithic structures is 90% or more of the value of the design class, the strength control at the design age is not carried out.
4.3 The control of concrete strength for each type of rated strength specified in 4.2 is carried out according to one of the following schemes:
- scheme A - determination of the characteristics of the homogeneity of concrete in terms of strength, when at least 30 single results of determining the strength obtained during the control of the strength of concrete of previous batches of BSG or prefabricated structures in the analyzed period are used;
- scheme B - determination of the characteristics of the homogeneity of concrete in terms of strength, when at least 15 single results of determining the strength of concrete in a controlled batch of BSG or prefabricated structures and previous controlled batches in the analyzed period are used;
- scheme B - determination of the characteristics of the homogeneity of concrete in terms of strength, when the results of non-destructive testing of concrete strength of one current controlled batch of structures are used, while the number of unit values of concrete strength must comply with the requirements of 5.8;
- scheme D - without determining the characteristics of the homogeneity of concrete in terms of strength, when in the manufacture of individual structures or in the initial period of production it is impossible to obtain the number of results for determining the strength of concrete provided for in schemes A and B, or when carrying out non-destructive testing of concrete strength without building calibration dependencies, but with using universal dependencies by linking them to the concrete strength of a controlled batch of structures.
Note - In exceptional cases (if it is impossible to carry out continuous testing of the strength of concrete of monolithic structures using non-destructive methods), it is allowed to determine the strength of concrete by control samples made at the construction site and hardened in accordance with the requirements of 5.4, or by control samples taken from the structures. In this case, the actual strength class of concrete in a batch of structures at 15 is calculated by the formula (11), at<15 - по формуле (13).
4.4 Concrete strength control is carried out:
- for BSG - according to schemes A, B, D;
- for prefabricated structures - according to schemes A, B, C, D;
- for monolithic structures - according to schemes B, G.
4.5 As characteristics of the homogeneity of concrete in terms of strength, used to determine the required strength of concrete or the actual class of concrete, the coefficients of variation of the strength of concrete are calculated:
- average - for all batches of BSG and prefabricated structures for the analyzed period - when controlled according to scheme A;
- moving - average for the controlled and the last previous batches - when controlled according to scheme B;
- current - for the current batch of BSG and structures - during control according to scheme B.
4.6 When monitoring and assessing the strength of BSG concrete at the manufacturer:
- according to scheme A:
determine the actual concrete strength and the current coefficient of variation of concrete strength in each batch made during the analyzed period,
calculate the average coefficient of variation of concrete strength for the analyzed period,
determine according to 7.1 the required concrete strength for the next controlled period,
assess the strength of concrete for each batch made in the controlled period according to 8.2;
- according to scheme B:
the characteristics of the homogeneity of concrete in terms of strength are calculated: the current coefficient of variation of the strength of concrete and the sliding coefficient of variation of the strength of concrete,
determine the required strength of concrete in a controlled batch,
- according to the scheme D:
determine the actual strength of concrete in each batch made in the controlled period,
4.7 When monitoring and assessing the strength of concrete in prefabricated structures:
- according to scheme A:
determine the actual strength of concrete in each batch of structures manufactured in the analyzed period,
calculate the characteristics of the homogeneity of concrete in terms of strength - the current coefficient of variation of the strength of concrete in each batch and the average coefficient of variation of strength for the analyzed period,
determine according to 7.1 the required concrete strength for the next controlled period according to the characteristics of the uniformity of concrete strength for the analyzed period,
assess the strength of concrete in accordance with 8.2 for each batch of structures manufactured in the controlled period;
- according to scheme B:
determine the actual strength of concrete in a controlled batch,
calculate the characteristics of the homogeneity of concrete in terms of strength - the current coefficient of variation of the strength of concrete and the sliding coefficient of variation of the strength of concrete in the controlled batch,
determine in accordance with 7.1 the required strength of concrete in a controlled batch,
assess the strength of concrete in the current controlled batch according to 8.2;
- according to scheme B:
determine the actual strength of concrete in a controlled batch,
calculate the current coefficient of variation of concrete strength in the controlled batch,
determine according to 7.1 the required concrete strength for the controlled batch,
assess the strength of concrete in a controlled batch according to 8.2;
- according to the scheme D:
determine the actual strength of concrete in a controlled batch,
determine the required concrete strength according to 7.1,
assess the strength of concrete in a controlled batch according to 8.2.
4.8 When monitoring and assessing the strength of concrete in batches of monolithic structures:
- according to scheme B:
determine by non-destructive methods the actual strength of concrete in a controlled batch,
calculate the current coefficient of variation of concrete strength in a controlled batch, taking into account the error of the applied non-destructive methods when determining the strength according to 6.5,
determine according to 7.3 and 7.4 the actual strength class of concrete,
assess the actual concrete strength class in accordance with 8.3 in the controlled batch;
- according to the scheme D:
determine by non-destructive or destructive methods (in exceptional cases - see 4.3) the actual strength of concrete in a controlled batch,
determine according to 7.5 the actual strength class of concrete in the controlled batch,
carry out according to 8.3 assessment of the strength of concrete in a controlled batch.
5 Determination of the strength of concrete
5.1 The composition of a batch of BSG should include a BSG of one nominal composition according to GOST 27006 prepared using one technology.
The composition of a batch of prefabricated or monolithic structures includes structures made from a concrete mixture of the same nominal composition, molded using the same technology.
The duration of the manufacture of a batch of BSG or structures should be:
- at least one shift - for BSG and prefabricated structures and one day - for monolithic structures;
- no more than one month - for BSG and one week - for prefabricated and monolithic structures.
It is allowed, during control according to schemes A and B, to combine into one batch of BSG of different nominal composition and one class of concrete in terms of strength, if the following conditions are met:
- the maximum of the average values of the coefficient of variation of the strength of concretes of the combined compositions for the analyzed period does not exceed 13%;
- the difference between the maximum and minimum values of the coefficient of variation of the strength of the concrete of the combined compositions for the analyzed period does not exceed 2%;
- the largest aggregate size in the combined compositions differs by no more than two times, and the cement consumption in these compositions is no more than 10% of the average value.
The conditions for combining concrete compositions are checked once a year according to the results of determining the characteristics of the homogeneity of concrete in terms of strength separately for each nominal composition for the last two controlled periods.
When combined in one batch of BSG of different compositions, the value of the coefficient of variation of the strength of concrete in the first controlled period is determined as the arithmetic mean of the coefficients of variation for individual nominal compositions.
5.2 When determining the strength of concrete according to control samples, at least two BSG samples are taken from each batch and at least one sample:
per shift - at the factory - manufacturer of prefabricated structures;
per day - at the enterprise - the manufacturer of BSG and the construction site in the manufacture of monolithic structures.
In exceptional cases (see 4.3), when determining the strength of concrete of monolithic structures using control samples, the number of concrete samples taken from each batch of the structure must be at least six.
5.3 From each sample of the concrete mix, a series of control samples is made to determine each type of rated strength specified in 4.2.
The number of samples in a batch is taken by GOST 10180.
It is allowed to make a series of control samples for determining the strength of concrete of prefabricated structures at the design age, not from each sample, but from at least two samples taken from one batch per week with a concrete strength class of B30 and below, and four samples taken from two batches. per week for concrete strength class B35 and higher.
When controlling the strength of aerated concrete from the finished structures of each batch or from blocks made simultaneously with the structures, concrete samples are cut out or drilled out in at least two sections.
5.4 Test specimens of concrete of prefabricated structures must be hardened in the same conditions as the structures before determining the tempering or transfer strength. Subsequent hardening of samples intended to determine the strength of concrete at the design age should take place under normal conditions at a temperature of (20 ± 3) ° С and a relative humidity of (95 ± 5)%.
Control samples from BSG, intended for the manufacture of monolithic structures, must harden at the enterprise - the manufacturer of the concrete mixture under normal conditions.
Control samples made at the construction site during the incoming control of the concrete strength of BSG batches must harden under normal conditions.
Control samples made at a construction site for monitoring and assessing the strength of concrete in batches of monolithic structures in accordance with 4.3 must harden in the conditions provided for by the project for the production of work or technological regulations for the production of monolithic concrete and reinforced concrete structures of this construction object.
5.5 Control of concrete strength by indirect non-destructive methods is carried out with the obligatory use of calibration dependencies previously established in accordance with the requirements GOST 22690 and GOST 17624.
5.6 When controlling the tempering and transfer strength of concrete of prefabricated structures by non-destructive methods, the number of controlled structures of each type is taken to be at least 10% or at least 12 structures from a batch. If a batch consists of 12 structures or less, a continuous inspection is carried out. In this case, the number of controlled sections must be at least one per 4 m of the length of linear structures and at least one per 4 m of the area of flat structures.
5.7 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.
5.8 When testing the strength of concrete of monolithic structures at design age by non-destructive methods, continuous non-destructive testing of the strength of concrete of all structures of the controlled batch is carried out. In this case, the number of controlled areas must be at least:
- three for each grip - for flat structures (walls, floors, foundation slabs);
- one per 4 m in length (or three per grip) - for each linear horizontal structure (beam, crossbar);
- six 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.
The number of measurements carried out at each controlled area is taken by GOST 17624 or GOST 22690.
Note - When conducting surveys and expert assessment of the quality of linear vertical structures, the number of controlled areas should be at least four.
5.9 The actual strength of concrete in a batch, MPa, is calculated by the formula
where is the unit value of concrete strength, MPa;
The total number of unit values of concrete strength in the batch.
The unit value of concrete strength is taken as follows:
- when testing by samples - the average strength of a series of samples made from one sample of BSG, to control one type of standardized strength specified in 4.2;
- when inspected by non-destructive methods - the average strength of concrete of the controlled area or zone of the structure or the average strength of concrete of a separate structure.
The rule for choosing a unit value of concrete strength when using non-destructive methods, depending on the type of structures, is given in Appendix A.
5.10 The strength of concrete is determined by the results of testing samples according to GOST 10180 and GOST 28570 or non-destructive methods for GOST 17624 and GOST 22690.
The strength of concrete of prefabricated structures at the design age and the tensile strength of concrete are determined only by reference samples.
6 Determination of the characteristics of the homogeneity of concrete in terms of strength
6.1 The duration of the analyzed period for determining the characteristics of the homogeneity of concrete in terms of strength according to schemes A and B is set from one week to three months.
The number of unit values of concrete strength during this period, depending on the selected control scheme, is taken according to 4.3.
6.2 For each batch of BSG or structures, the standard deviation and the current coefficient of variation of concrete strength are calculated. The specified characteristics are calculated for all types of rated strength specified in 4.2.
It is allowed not to calculate the coefficient of variation of concrete strength at the design age for prefabricated structures, but to take it equal to 85% of the coefficient of variation of the tempering strength.
6.3 The standard deviation of the strength of concrete in a batch, MPa, is calculated by the formula
6.4 With the number of unit values of concrete strength in a batch from two to six, the value of the standard deviation is allowed to be calculated by the formula
The coefficient is taken according to table 1.
Table 1 - Coefficient
Number of single values | |||||
Coefficient |
6.5 When testing the strength of concrete by non-destructive methods, if the strength of a site, zone or a separate structure is taken as a unit value, the standard deviation of the strength of concrete in a batch is calculated by the formula
where is determined by the formula
where is taken equal:
- for the method of separation with spalling - 0.04 of the average concrete strength of the areas used in the construction of the calibration dependence for an anchor device with an embedment depth of 48 mm; 0.05 medium strength - at a depth of 35 mm; 0.06 medium strength - at a depth of 30 mm; 0.07 medium strength - at a depth of 20 mm;
- for destructive methods - 0.02 of the average strength of the tested samples.
The value is determined when constructing the calibration dependence according to the formula (6). The value must be at least 0.7.
where and are the values of the concrete strength of the sections (or series of samples), determined by destructive and non-destructive methods when establishing the calibration dependence.
6.6 The current coefficient of variation of concrete strength in a batch of BSG or structures is determined by the formula
6.7 When controlled according to scheme A, the average value of the coefficient of variation of concrete strength, and when controlled according to scheme B, the sliding coefficient of variation of concrete strength for the analyzed period is calculated by the formula
where are the coefficients of variation of concrete strength in each batch;
- the number of unit values of concrete strength in each batch;
- the total number of unit values of concrete strength for the analyzed period.
When controlled according to scheme B, the current coefficient of variation of concrete strength in the controlled batch is calculated by the formula (7).
6.8 When controlling irregularly produced lots of BSG and prefabricated structures, it is allowed to take the coefficient of variation of the strength of concrete equal to the coefficient of variation of the strength of concrete made from BSG of a different composition, provided it is manufactured using the same technology, from the same materials and differing in strength by no more than two classes.
7 Determination of the required strength and the actual strength class of concrete
7.1 The required strength of each type of concrete for BSG and prefabricated structures, MPa, is calculated by the formula
When controlling according to schemes A and B, the coefficient is taken according to Table 2, depending on the average coefficient of variation of the concrete strength for the analyzed period or the current coefficient of variation of the concrete strength of the controlled batch; when controlled according to scheme B, the coefficient is calculated by the formula
where the coefficient is taken according to table 3, depending on the total number of unit values of concrete strength in the controlled batches of BSG or structures, according to which the sliding coefficient of variation of strength is calculated.
When controlled according to the scheme D, the coefficient is taken according to table 4.
Number of unit values of concrete strength | Coefficient |
> 30 to 60 incl. | |
Table 4 - Coefficient of required strength when testing according to scheme D
Concrete type | Coefficient |
All types of concrete (except for dense silicate and cellular concrete) | |
Dense silicate | |
Cellular |
7.2 When controlling according to scheme A, the duration of the controlled period during which the value of the required strength determined in the analyzed period can be used should be taken from one week to one month.
7.3 The actual class of concrete for the strength of monolithic structures when controlled according to scheme B is calculated by the formula
The value of the coefficient is taken according to table 2.
7.4 The actual class of concrete for the strength of individual vertical monolithic structures when controlled according to scheme B is calculated by the formula
where is the coefficient taken according to table 5 depending on the number of unit values.
Table 5 - Coefficient
7.5 The actual class of concrete for the strength of monolithic structures when controlled according to scheme D is taken equal to 80% of the average strength of concrete of structures, but not more than the minimum particular value of concrete strength of a separate structure or a section of a structure included in the controlled batch:
8 Acceptance of concrete by strength
8.1 Acceptance of lots of BSG and structures is carried out:
- in terms of strength at intermediate and design age - for BSG and monolithic structures;
- for release, transfer and design strength - for prefabricated concrete.
8.2 A batch of BSG and a batch of prefabricated structures are subject to acceptance for concrete strength if the actual concrete strength in the batch is not lower than the required strength, and the minimum unit strength value is not less than and not less than the standardized concrete strength class.
8.3 A batch of monolithic structures is subject to acceptance for the strength of concrete, if the actual concrete strength class in each individual structure of this batch is not lower than the design concrete strength class:
8.4 The control of the concrete strength of prefabricated structures at the design age is carried out periodically according to 5.3 by comparing the required concrete strength at the design age with the average concrete strength at this age of all batches controlled for a week.
The strength of concrete of prefabricated structures at the design age is recognized as meeting the requirements if the conditions of 8.2 are met. The test results apply to all batches of concrete produced in a week.
In case of violation of these conditions, the manufacturer is obliged to inform the consumer about this within three days after the end of all tests.
8.5 The possibility of using (or the need to strengthen) batches of structures, the actual strength or the actual concrete strength class of which does not meet the requirements of 8.2-8.4, must be agreed with the design organization of the construction object.
8.6 The values of the required strength of concrete BSG and prefabricated structures should be indicated in the document on the quality of BSG batches according to GOST 7473 and prefabricated structures - by GOST 13015.
8.7 The values of the actual strength class of concrete of each monolithic structure should be given in the document on the results of the current control or the document on the results of the survey.
Appendix A (mandatory). Selection of a unit value for concrete strength under non-destructive testing
Appendix A
(required)
For a unit value of concrete strength during non-destructive testing, the following is taken:
- when inspecting prefabricated structures (flat and hollow-core floor slabs and coverings, road slabs, panels of internal load-bearing walls, wall blocks, as well as pressure and non-pressure pipes) - the average strength of the concrete structure, calculated as the arithmetic mean of the concrete strength of the controlled sections of the structure;
- when inspecting other types of structures - the average strength of the concrete of the structure or of the controlled area or zone of the structure, or of a part of a monolithic and prefabricated monolithic structure.
UDC 691.32: 620.17: 006.354 | ISS 91.100.30 | |
Key words: concrete, rules for monitoring and assessing strength, uniformity of concrete in terms of strength, acceptance of concrete in terms of strength |
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Electronic text of the document
prepared by JSC "Kodeks" and verified by:
official publication
M .: Standartinform, 2018
