Approved and enacted by
Order of the Federal Agency on
Technical Regulation and
Metrology No. 28-ст dated
March 21, 2012
INTERSTATE STANDARD
CONCRETES
RULES FOR CONTROL AND ASSESSMENT OF STRENGTH
Concretes. Rules for control and assessment of strength
(EN 206-1:2000, NEQ)
GOST 18105-2010
MKS 91.100.30
Effective as of
September 01, 2012
Foreword
Objectives, basic principles and basic procedure for interstate standardization works are stipulated in
GOST 1.0-92 “Interstate standardization system. Basic Provisions” and MSN 1.01-01-2009 “System of
interstate regulatory documents for construction. General provisions. Basic provisions”.
Information on the Standard
1. Developed by the Scientific Research, Design and Technology Institute for Concrete and Reinforced
Concrete (NIIZhB – branch of Federal Unitary Enterprise NITs Stroitelstvo).
2. Introduced by the Technical Committee for Standardization TK 465 “Construction”.
3. Accepted by the Interstate Scientific and Technical Commission for Standardization, Technical Rate
Setting and Certification in Construction (Appendix E to Protocol No. 37 as of October 07, 2010).
The following countries voted pro:
Short name of
the country by
IC (ISO 3166)
004-97
Azerbaijan
Armenia
Kazakhstan
Kirgizia
Moldova
Country
code by IC
(ISO 3166)
004-97
AZ
AM
KZ
KG
MD
Short name of the national agency of state
construction management
State Committee for Construction (Gosstroy)
Ministry of Urban Development
Agency for Construction, Housing and Utilities
State Committee for Construction (Gosstroy)
Ministry of Construction and Regional
Development
Russian
Federation
RU
Tajikistan
TJ
Uzbekistan
UZ
Ukraine
UA
Department of Regulation of Town Planning
Activities of the Ministry of Regional
Development
Agency for Construction and Architecture at the
Government
State Committee on Architecture and
Construction (Gosarkhitektstroy)
Ministry of Construction and Regional
Development
4 This Standard takes into account the basic regulatory provisions of the European standard
EN 206-1:2000 “Concrete – Part 1: Specification, performance, production and conformity” (EN 206-1:2000
“Concrete – Part 1: Specification, performance, production and conformity”) in terms of control and
assessment of strength of concrete.
Degree of compliance is nonequivalent (NEQ).
5. Interstate standard GOST 18105-2010 was enacted as a national standard of the Russian Federation
on September 01, 2012 by Order of the Federal Agency on Technical Regulation and Metrology No. 28-ст
dated March 21, 2012.
6. Replaced GOST 18105-86<*>.
-------------------------------<*> GOST R 53231-2008 is effective within the territory of the Russian Federation until September 01,
2012.
Information on enactment (termination) of this Standard and changes thereto is published in a
monthly index “National Standards”.
Information on changes to this Standard is published in index (catalog) “National Standards”, and the
text of changes is published in informative indices “National Standards”. In case of revision or cancellation of
this Standard, the relevant information will be published in an informative index “National Standards”.
1. Scope of application
This Standard applies to all types of concretes, for which the strength is rated, and establishes the rules
for control and assessment of strength of concrete mixture ready for use (hereinafter referred to as – CMR),
concrete of monolithic, cast-in-place and precast and reinforced construction in case of production control of
strength of concrete.
Rules of this Standard may be used for surveys of concrete and reinforced concrete constructions, as
well as in case of expert assessment of quality of concrete and reinforced concrete constructions.
Compliance with this Standard shall guarantee the design and characteristic strength of concrete
constructions adopted in the design.
2. Referenced Standards
This Standard refers to the following standards:
GOST 7473-2010. Concrete mixes. Specifications
GOST 10180-90. Concretes. Methods for strength determination using reference specimens
GOST 13015-2003. Concrete and reinforced concrete products for construction. General technical
requirements. Rules of acceptance, marking, transportation and storage.
GOST 17624-87. Concretes. Ultrasonic Method of Strength Determination
GOST 22690-88. Concretes. Determination of Strength by Mechanical Methods of Nondestructive
Testing
GOST 27006-86. Concretes. Rules for Mix Proportioning
GOST 28570-90. Concretes. Methods of Strength Evaluation on Cores Drilled from Structures
Note. When applying this Standard, it is expedient to verify the validity of the referenced standards in
the public information system – on the official site of the Federal Agency on Technical Regulation and
Metrology on the Internet or in the annually published information index “National Standards”, which was
published as of January 01 of the current year, and in the relevant monthly information indices published
during the current year. In case a referenced standard is replaced (modified), the replaced (modified)
standard shall be used for the purposes of this Standard. In case a referenced standard is canceled without
any replacement, the provision containing a reference thereto shall be used to the extent not covering this
reference.
3. Terms, definitions and designations
3.1. Terms and definitions
The following terms with the corresponding definitions are used in this Standard:
3.1.1. Rated concrete strength: a strength of concrete in the design age or its part in the intermediate
age established in the regulatory or technical document according to which the construction or CMR shall be
made.
Note. Depending on the type of strength in the design age, the following classes of concrete shall be
established:
B – concrete class by compression strength;
Bt – concrete class by axial tension strength;
Btb – concrete class by bending tension strength.
3.1.2. Required strength of concrete: a minimum acceptable average value of concrete strength in the
controlled batches of CMR or constructions corresponding to the rated concrete strength in its actual
homogeneity.
3.1.3. Actual concrete classes: a value of the concrete class according to the strength of monolithic
constructions calculated based on the results of determination of the actual concrete strength and its
homogeneity in the controlled batch.
3.1.4. Actual strength of concrete: an average value of concrete strength in batches of constructions or
CMR calculated based on the results of its determination in the controlled batch.
3.1.5. Sample of concrete mixture: a volume of CMR of one nominal composition from which one or
several series of reference specimens shall be made at the same time.
3.1.6. Series of reference specimens: several samples made from one sample of CMR or selected from
one construction, solidifying under identical conditions and tested at the same age to determine the actual
strength of one type.
3.1.7. Batch of concrete mixture: a volume of CMR of one nominal composition produced or packed in
a definite time.
3.1.8. Batch of monolithic constructions: a part of monolithic construction, one or more monolithic
constructions produced in a definite time.
3.1.9. Batch of prefabricated constructions: constructions of one type, consistently produced according
to one technology from the same type of materials.
3.1.10. Controlled area of construction: a section of construction where the unit value of concrete
strength shall be determined by nondestructive methods.
3.1.11. Area of construction: a part of controlled construction the concrete strength of which differs
from the average strength of this construction by more than 15%.
3.1.12. Analyzed period: a period of time for which the average value of the coefficient of variation of
concrete strength for batches of CMR or constructions produced for this period shall be calculated.
3.1.13. Current coefficient of variation of concrete strength: a coefficient of variation of concrete
strength in the controlled batch of CMR or constructions.
3.1.14. Average coefficient of variation of concrete strength: an average value of the coefficient of
variation of concrete strength for the analyzed period under control according to Schemes A and C.
3.1.15. Sliding coefficient of variation of concrete strength: a coefficient of variation of the concrete
strength calculated as an average for the current batch and previous controlled batches of CMR or
constructions under control according to Scheme B.
3.1.16. Controlled period: a period of time during of which the required strength of concrete shall be
assumed as constant in accordance with the coefficient of variation for the previous analyzed period.
3.1.17. Current control: a control of concrete strength of the batch of CMR or constructions, where the
values of actual strength and homogeneity of concrete by strength (current coefficient of variation) shall be
calculated based on the results of control of this batch.
3.1.18. Destructive methods for determining the concrete strength: a determination of the concrete
strength on the basis of reference specimens made of concrete mixture as per GOST 10180 or selected from
constructions as per GOST 28570.
3.1.19. Direct nondestructive determination of concrete strength: a determination of the concrete
strength according to “separation with shearing” and “rib shearing” as per GOST 22690.
3.1.20. Indirect nondestructive methods for determining the strength of concrete: determination of
concrete strength by the predetermined calibration dependences between the strength of concrete,
determined by one of destructive or direct nondestructive methods, and indirect characteristics of strength
determined according to GOST 22690 and GOST 17624.
3.1.21. Pour: a volume of concrete of monolithic construction or a part thereof placed during
continuous concreting of one or more batches of CMR in a definite time.
3.1.22. Unit value of strength: a value of the actual strength for concrete of the rated type accounted
in case of calculation of characteristics of homogeneity of concrete:
- for CMR – an average value of the concrete strength of a sample of concrete mixture;
- for prefabricated constructions – an average value of the concrete strength of a sample of concrete
mixture or an average value of the concrete strength of a section of the construction, or an average value of
the concrete strength of one construction;
- for monolithic constructions – an average value of the concrete strength of a section of the
construction or concrete of one construction.
3.2. Designations
Bнорм – design strength class of concrete, MPa;
Bф – actual strength class of concrete, MPa;
Ri , Rimin , Rimax – unit, minimum and maximum values of concrete strength in the batch, MPa;
Rm – actual average strength of concrete of a separate batch, MPa;
RТ , RТ – required average strength of concrete of CMR or constructions in the controlled batch or in
the controlled period, MPa;
Sm – standard deviation of the concrete strength in the controlled batch, MPa;
SН.М – standard deviation of the concrete strength in the controlled batch based on the results of its
determination by nondestructive methods, MPa;
SТ – calculated standard deviation of the used calibration dependence, MPa;
S Т.Н.М – standard deviation of the developed calibration dependence, MPa;
SТ.Р.М – standard deviation of destructive or direct nondestructive methods used in development of
the calibration dependence, MPa;
Vm – current coefficient of variation of concrete strength in the batch, %;
Vm – average coefficient of variation of concrete strength for the analyzed period, %;
Vс – sliding coefficient of variation of concrete strength for the analyzed period, %;
Wm – range of concrete strength in the batch, MPa;
n – number of unit values of concrete strength in the batch;
 – coefficient for calculation Sm (n <= 6);
r – correlation factor of calibration dependence;
K Т – coefficient of required strength;
t – coefficient for calculation K Т and Bф ;
t – coefficient for calculation K Т and Bф ;
4. General Provisions
4.1. Control and assessment of concrete strength at enterprises and in organizations producing CMR,
prefabricated, cast-in-place and precast concrete and reinforced constructions shall be carried out by
statistical methods taking into account characteristics of homogeneity of concrete according to its strength.
Acceptance of concrete by comparing its actual strength with the required strength without taking into
account characteristics of homogeneity of concrete strength shall not be allowed.
4.2. All types of the rated concrete strength shall be subject to control:
- strength in the design age – for CMR, prefabricated, cast-in-place and precast and monolithic
constructions;
- handling and transfer strength – for prefabricated constructions;
- strength in the intermediate age – for CMR and monolithic constructions (in case of removal of loadcarrying formwork, loading of constructions until they reach the design strength, etc.).
Should the rated handling strength or transfer strength of prefabricated constructions or concrete
strength in the intermediate age for CMR or monolithic constructions be 90% or more of the value of the
design class, control of concrete strength in the design age shall not be carried out.
4.3. Control of concrete strength for each type of the rated concrete strength specified in 4.2 shall be
carried by one of the following Schemes:
- Scheme A – determination of characteristics of homogeneity of the concrete strength, when using at
least 30 single results of determination of strength obtained by control of strength of concrete of previous
batches of CMR or prefabricated structures in the analyzed period;
- Scheme B – determination of characteristics of homogeneity of the concrete strength, when using at
least 15 single results of determination of concrete strength in controlled batches of CMR or prefabricated
constructions and previous controlled batches in the analyzed period;
- Scheme C – determination of characteristics of homogeneity of the concrete strength, when using the
results of nondestructive control of concrete strength of one current controlled batch of constructions, and
the number of unit values of concrete strength shall conform to the requirements of 5.8;
- Scheme D – without determination of characteristics of homogeneity of concrete strength, if during
manufacture of separate constructions or in the initial period of production it is not possible to obtain the
number of the results of determination of concrete strength provided for by Schemes A and B , or in case of
nondestructive control of concrete strength without developing calibration dependences, but using universal
dependences by linking them to the concrete strength of the controlled batch of constructions.
Note. In exceptional cases (with the impossibility of complete control of concrete strength of
monolithic structures using nondestructive methods), the concrete strength may be determined by reference
specimens made at the construction site and solidified in accordance with the requirements of 5.4, or
according to reference specimens selected from the constructions. However, the actual class of concrete
strength in the batch of constructions at n> = 15 shall be calculated by the formula (11) , where n <15 * –
formula (13) .
4.4. Control of concrete strength shall be carried out:
- for CMR – according to Schemes А, B, D;
- for prefabricated constructions – according to Schemes А, B, C, D;
- for monolithic constructions – according to Schemes C, D.
4.5. Coefficients of variation of concrete strength shall be calculated as characteristics of homogeneity
of concrete strength used to determine the required strength of concrete RТ or actual class of concrete
Bф :
- average Vm – for all batches of CMR and prefabricated constructions for the analyzed period – under
control according to Scheme A;
- sliding Vс – average for controlled and last previous batches – under control according to Scheme B;
- current Vm – for the current batch of CMR and constructions – under control according to Scheme C.
4.6. In case of control and assessment of the concrete strength of CMR at the manufacturer:
- according to Scheme A:
the actual strength of concrete Rm and the current coefficient of variation of concrete strength Vm in
each batch manufactured for the analyzed period shall be determined,
the average coefficient of variation of concrete strength for the analyzed period shall be calculated,
the required strength of concrete RТ for the next controlled period shall be determined according to
7.1,
assessment of the concrete strength of each batch manufactured in the controlled period shall be
carried out according to 8.2;
- according to Scheme B:
the actual strength of concrete Rm in the controlled batch shall be determined,
the homogeneity characteristics of concrete strength, namely, the current coefficient of variation of
concrete strength Vm and the sliding coefficient of variation of concrete strength Vс , shall be calculated,
the required strength of concrete RТ in the controlled batch shall be determined,
assessment of concrete strength in the controlled batch shall be carried out according to 8.2;
- according to Scheme D:
assessment of the concrete strength of each batch manufactured in the controlled period shall be
determined;
the required strength of concrete RТ determined according to 7.1,
assessment of the concrete strength in the controlled batch shall be carried out according to 8.2;
4.7. In case of control and assessment of the concrete strength of prefabricated constructions:
- according to Scheme A:
assessment of the actual strength of concrete of each batch manufactured in the controlled period
shall be determined;
the homogeneity characteristics of concrete strength, namely, the current coefficient of variation of
concrete strength
Vm in each batch and the sliding average coefficient of variation of concrete strength Vm
for the analyzed period, shall be calculated,
the required concrete strength RТ for the next controlled period by the characteristics of
homogeneity of concrete strength for the analyzed period shall be determined according to 7.1,
assessment of the concrete strength of each batch of constructions manufactured in the controlled
period shall be carried out according to 8.2;
- according to Scheme B:
the actual strength of concrete Rm in the controlled batch shall be determined,
the homogeneity characteristics of concrete strength, namely, the current coefficient of variation of
concrete strength Vm and the sliding coefficient of variation of concrete strength Vс in the controlled batch,
shall be calculated,
the required strength of concrete in the controlled batch shall be determined according to 7.1,
assessment of the concrete strength in the current controlled batch shall be carried out according to
8.2;
- according to Scheme C:
the actual strength of concrete Rm in the controlled batch shall be determined,
the current coefficient of variation of concrete strength Vm in the controlled batch shall be calculated,
the required strength of concrete for the controlled batch shall be determined according to 7.1,
assessment of concrete strength in the controlled batch shall be carried out according to 8.2;
- according to Scheme D:
the actual strength of concrete Rm in the controlled batch shall be determined,
the required strength of concrete RТ determined according to 7.1,
assessment of the concrete strength in the controlled batch shall be carried out according to 8.2;
4.8. In case of control and assessment of the concrete strength of batches of monolithic constructions:
- according to Scheme C:
the actual strength of concrete Rm in the controlled batch shall be determined by nondestructive
methods,
the current coefficient of variation of concrete strength Vm in the controlled batch, taking into account
the error of nondestructive methods used in determining the strength according to 6.5, shall be calculated,
the actual class of concrete Bф shall be determined according to 7.3 and 7.4,
assessment of the actual class of concrete strength in the controlled batch shall be carried out
according to 8.3;
- according to Scheme D:
the actual strength of concrete Rm in the controlled batch shall be determined by nondestructive or
destructive methods (in exceptional cases – see 4.3),
assessment of the actual class of concrete strength in the controlled batch shall be determined
according to 7.5;
assessment of the concrete strength in the controlled batch shall be carried out according to 8.3;
5. Determination of concrete strength
5.1. CMR of the same nominal composition according to GOST 27006 prepared by the same technology
shall be included in the batch of CMR.
Constructions made of concrete mixture of the same nominal composition molded according to the
same technology shall be included in the batch of prefabricated or monolithic constructions.
Production time of the batch of CMR or constructions shall be:
- not less than one shift – for CMR and prefabricated constructions and one day – for monolithic
constructions;
- not more than one month – for CMR and one week – for prefabricated constructions and monolithic
constructions.
Consolidation into one batch of CMR of different nominal composition and one class of concrete
strength shall be allowed in case of control according to Schemes A and B, if the following conditions are
fulfilled:
- the maximum of average values of the coefficient of variation of strength of concrete of combined
compositions for the analyzed period shall not exceed 13%;
- the difference between the maximum and minimum values of the coefficient of variation of strength
of concrete of combined compositions for the analyzed period shall not exceed 2%;
- the maximum fineness of aggregate in the joined compositions shall differ not more than two times,
and the quantity of cement in these compounds – not more than by 10% of the average value.
Conditions of combination of concrete compositions shall be checked once per year based on the
results of determination of the homogeneity characteristics of concrete strength for each nominal
composition for the last two controlled period.
The value of the coefficient of variation of concrete strength in the first controlled period shall be
determined as the arithmetic mean value of coefficients of variation for individual nominal compositions in
case of consolidation of different compounds into one batch of CMR.
5.2. At least two samples from each batch of CMR shall be taken to determine the strength of concrete
according to reference specimens and at least one sample:
per shift – at the manufacturing plant of prefabricated constructions;
per day – at the manufacturing plant of CMR and at the construction site during manufacture of
monolithic constructions.
In exceptional cases (see. 4.3), the number of samples of concrete taken from each batch of
construction shall be not less than six when determining the strength of concrete of monolithic constructions
according to reference specimens.
5.3. Series of reference specimens to determine the strength of each species of the rated concrete
strength specified in 4.2 shall be produced from each sample of concrete mixture.
Number of samples in series shall be accepted as per GOST 10180.
It shall be allowed to produce a series of reference specimens to determine the strength of concrete of
prefabricated constructions in the design age not from each sample, but not less than from two samples
taken from the same batch per week with the class of concrete strength B30 and lower, and four samples
taken from the two batches per week with the class of concrete strength B35 and higher.
Samples of concrete shall be saw out or drilled out not less than at two areas in case of control of
strength of cellular concrete from constructions of each batch produced simultaneously with constructions.
5.4. Reference specimens of concrete of prefabricated constructions shall harden at the same
conditions with constructions until the handling strength or transfer strength is determined. Subsequent
curing of samples for determining of the concrete strength in the design age shall be carried out under
normal conditions of temperature (20 +/- 3) °C and relative humidity (95 +/- 5)%.
Reference specimens of CMR for production of monolithic constructions shall harden at the
manufacturer of concrete mixture under normal conditions.
Reference specimens produced at the construction site during input control of the concrete strength of
batches of CMR shall harden under normal conditions.
Reference specimens produced at the construction site to control and assess the strength of concrete
of batches of monolithic constructions according to 4.3 shall harden in the conditions provided for by the
work production plan or process regulations for production of monolithic concrete and reinforced
constructions of this construction object.
5.5. Control of concrete strength by indirect nondestructive methods shall be carried out with the
mandatory use of predetermined calibration dependences in accordance with the requirements of
GOST 22690 and GOST 17624.
5.6. Number of controlled constructions of each type shall be taken not less than 10% and not less than
12% of constructions from the batch in case of control of the handling strength or transfer strength of
prefabricated constructions by nondestructive methods. Complete control shall be carried out if the batch
consists of 12 constructions or less. Thus, the number of controlled areas shall be not less than one for 4 m
length of linear constructions and not less than one for 4 m2 of flat constructions.
5.7. At least one construction of each type (column, wall, ceiling, bolt, etc.) from the controlled batch
shall be under control in case of control of concrete strength of monolithic constructions in the intermediate
age by nondestructive methods.
5.8. Nondestructive testing of the concrete strength of all construction of the controlled batch shall be
carried out by nondestructive methods in case of control of the concrete strength of monolithic constructions
in the design age. At the same time, the number of controlled areas shall be not less than:
- three for each pour – for flat constructions (walls, floors, foundation slabs);
- one for 4 m length (or three for pour) – for each linear horizontal construction (beam, bolt);
- six for each construction – for linear vertical construction (column, pier).
Total number of measurement areas for calculating of the characteristics of homogeneity of concrete
strength of the batch of constructions shall be at least 20.
Number of measurements for each controlled area shall be accepted according to GOST 17624 or
GOST 22690.
Note. Number of controlled areas shall be at least four in case of surveys and expert assessment of
quality of linear vertical constructions.
5.9. Actual concrete strength in the batch Rm , MPa, shall be calculated by the formula
n
Rm 
R
i 1
n
i
, (1)
where Ri – a unit value of concrete strength, MPa;
n – a general number of unit values of concrete strength in the batch;
Unit value of concrete strength shall be accepted as:
- in case of control according to samples – the average strength of series of samples produced from
one sample of CMR to control one type of the rated concrete strength specified in 4.2;
- in case of control by nondestructive methods – the average strength of concrete of the controlled
section or area of construction or the average strength of concrete of an individual construction.
The rule for selection of a unit value of the concrete strength when using nondestructive methods
depending on the type of construction shall be given in Appendix A.
5.10. The strength of concrete shall be determined based on the results of sample tests as per
GOST 10180 and GOST 28570 or by nondestructive methods as per GOST 17624 and GOST 22690.
The strength of concrete of prefabricated structures in the design age and the tension strength of
concrete shall be determined only by reference specimens.
6. Determination of the characteristics of concrete homogeneity
by its strength
6.1. Duration of the analyzed period for determining the characteristics of homogeneity of concrete
strength according to Schemes A and B shall be set from one week to three months.
Number of unit values of concrete strength for this period depending on the selected scheme of
control shall be taken according to 4.3.
6.2. The standard deviation Sm and the current coefficient of variation of concrete strength Vm shall
be calculated for each batch of CMR or constructions. These characteristics shall be calculated for all types of
the rated concrete strength specified in 4.2.
The coefficient of variation of concrete strength in the design age shall not be computed and shall be
taken as 85% of the coefficient of variation of the handling strength for prefabricated constructions.
6.3. – standard deviation of the concrete strength in the batch Sm , MPa, shall be calculated by the
formula
n
 (R  R
Sm 
i
i 1
m
)2
. (2)
n 1
6.4. If the number of unit values of concrete strength in the batch is from two to six, the standard
deviation value Sm may be calculated by the formula
Sm 
Coefficient
Wm

. (3)
 shall be accepted according to Table 1.
Table 1
Coefficient 
Number of unit values n
Coefficient alpha
2
1.13
3
1.69
4
2.06
5
2.33
6
2.5
6.5. In case of control of the concrete strength by nondestructive methods, if the strength of a section,
area or individual construction is taken as a unit value, the standard deviation of Sm concrete strength in the
batch shall be calculated by the formula
ST 
1

S m   S H.M 
, (4)

n  1  0.7r  0.3

where
SТ shall be determined by the formula
2
2
, (5)
SТ  SТ.Н.М
 SТ.Р.М
where SТ.Р.М shall be equal to:
- for the method of separation with shear fracture – 0.04 of the average strength of concrete of
sections used in development of the calibration dependence at the anchor device with a depth of setting of
48 mm; 0.05 of the average strength – at a depth of 35 mm; 0.06 of the average strength – at a depth of
30 mm; 0.07 of the average strength – at a depth of 20 mm;
- for destructive methods – 0.02 of the average strength of the samples tested.
Value r shall be determined when developing the calibration dependence by the formula (6). Value r
shall be not less than 0.7.
n
r
 (R
iH
i 1
n
 (R
i 1
iH
 RiH )  ( Riф  Riф )
 RiH ) 
2
n
 (R
i 1
iф
, (6)
 Riф )
2
where Riф and RiH – values of the concrete strength of areas (or series of specimens) determined by
destructive and nondestructive methods in case of determination of the calibration dependence.
6.6. Current coefficient of variation of concrete strength Vm in the batch of CMR or constructions shall
be determined by the formula
Vm 
Sm
100 . (7)
Rm
6.7. In case of control according to Scheme A, the average value of coefficient of variation of concrete
strength Vm , under control according to Scheme B – the sliding coefficient of variation of concrete strength
for the analyzed period Vс shall be calculated by the formula
n
Vm (Vс ) 
V
mi ( ci )
i 1
 ni
, (8)
n
n
i 1
i
where Vmi ( ci ) – coefficients of variation of concrete strength in each i-batch;
ni – number of unit values of concrete strength in each i-batch;
n
n
i 1
Vm
i
– general number of unit values of concrete strength for the analyzed period;
In case of control according to Scheme C, the current coefficient of variation of the concrete strength
in the controlled batch shall be calculated by the formula (7).
6.8. Coefficient of variation of the concrete strength shall be taken as the coefficient of variation of
strength of concrete produced from CMR of different composition, if they are produced by the same
technology from the same materials and their strength differs by not more than two classes, in case of
control of irregularly produced batches of CMR and prefabricated constructions.
7. Determination of the required strength and actual class of concrete by strength
7.1. Required strength of concrete of each type RТ for CMR and prefabricated constructions, MPa,
shall be calculated by the formula
RТ  K Т Bнорм . (9)
In case of control according to Schemes A and B, the coefficient K Т shall be taken according to Table 2
depending on the average coefficient of variation of concrete strength for the analyzed period Vm or current
coefficient of variation of concrete strength of the controlled batch
Scheme B, the coefficient K Т shall be calculated by the formula
KТ 
1
1  t
Vс
100
, (10)
Vm ; in case of control according to
where the coefficient
t shall be taken according to Table 3 depending on the total number of unit
values of concrete strength in controlled batches of CMR or constructions according to which the sliding
coefficient of variation of strength is calculated.
Table 2
Coefficient of the required strength K Т in case of control of strength according to Schemes A and C
Average
coefficient
of variation
of strength
, %
6 and less
7
8
9
10
11
12
13
14
15
16
17
18
19
More than 20
Coefficient of the required strength Kr for
all types of concrete
(except for dense lime
Concrete of
and cellular) and
Dense lime
Cellular
massive
constructions (except
concrete
concrete
hydraulic
for massive hydraulic
structures
structures)
1.07
1.06
1.08
1.09
1.08
1.07
1.09
1.10
1.09
1.08
1.10
1.11
1.11
1.09
1.12
1.13
1.14
1.12
1.13
1.14
1.18
1.14
1.14
1.16
1.23
1.18
1.17
1.18
1.28
1.22
1.22
1.20
1.33
1.27
1.26
1.22
1.38
1.33
1.32
1.23
1.43
1.39
1.37
1.25
1.46
1.43
1.28
1.50
1.32
1.57
1.36
Infeasible region
1.39
Table 3
Coefficient t
Number of unit values of concrete
strength n
15
20
25
30
> 30 to 60 incl.
> 60
Coefficient talpha
1.76
1.73
1.71
1.70
1.68
1.64
Coefficient K Т shall be taken according to Table 4 in case of control according to Scheme D.
Table 4
Coefficient of the required strength K Т under control according to Scheme D
Type of concrete
All types of concrete (except for dense lime and cellular)
Dense lime
Cellular
Coefficient KT
1.28
1.33
1.43
7.2. Duration of the controlled period, during which the value of required strength determined in the
analyzed period may be used, shall be from one week to one month in case of control according to Scheme A.
7.3. Actual class of concrete according to strength of monolithic constructions Bф under control
according to Scheme C shall be calculated by the formula
Bф 
Rm
. (11)
KТ
Coefficient value K Т shall be accepted according to Table 2.
7.4. Actual class of concrete according to strength of separate vertical monolithic constructions Bф
under control according to Scheme C shall be calculated by the formula
Bф  Rm  t 
SТ
, (12)
n
where t – a coefficient accepted according to Table 5 depending on the number of unit values n.
Table 5
Coefficient t
n
tbeta
4
3.18
5
2.78
6
2.57
7
2.45
8
2.36
9
2.31
10
2.26
7.5. Actual class of concrete strength of monolithic constructions Bф , in case of control according to
Scheme D, shall be equal to 80% of the average concrete strength of constructions, but not more than the
minimum value of concrete strength of a separate construction or a section of the construction included in
the controlled batch:
Bф  0,8 Rm . (13)
8. Acceptance of concrete according to its strength
8.1. Acceptance of batches of CMR and constructions shall be provided:
- as per strength in the intermediate age and design age – for CMR and monolithic constructions;
- as per handling, transfer and design strength – for concrete of prefabricated constructions.
8.2. Batch of CMR and batch of prefabricated constructions shall be subject to acceptance by the
strength of concrete, if the actual concrete strength in the batch Rm is not less than the required strength
RТ , and the minimum unit value of strength Rimin – not less than the value ( RТ  4) and not less than the
rated class of concrete strength.
Rm  RТ ; (14)
B( Bt , Btb )  Rimin  ( RТ  4) . (15)
8.3. Batch of monolithic constructions shall be subject to acceptance by the strength of concrete, if the
actual class of concrete strength Bф in each construction of this batch is not lower than the design class of
concrete strength Bнорм :
Bф  Bнорм . (16)
8.4. Control of concrete strength of prefabricated constructions in the design age shall be carried out
periodically according to 5.3 by comparing the required concrete strength in the design age with the average
concrete strength in this age of all controlled batches for this week.
Strength of concrete of prefabricated constructions in the design age shall comply with the
requirements, if the conditions according to 8.2 are fulfilled. Results of check shall apply to all batches of
concrete manufactured for a week.
The manufacturer shall inform the consumer of violations of the conditions within three days upon
completion of all tests.
8.5. Ability to use (or necessity to strengthen) batches of constructions, actual strength or actual class
of concrete strength, which does not meet the requirements of 8.2 – 8.4, shall be agreed upon with the
design organization of the construction object.
8.6. Values of the required strength of concrete of CMR and prefabricated constructions shall be
specified in the document of quality of batches of CMR according to GOST 7473 and prefabricated
constructions – according to GOST 13015.
8.7. Values of the actual class of concrete strength of each monolithic construction shall be given in the
document on the results of current control or the document on the results of the survey.
Appendix A
(mandatory)
SELECTION OF UNIT VALUE OF CONCRETE STRENGTH
UNDER NONDESTRUCTIVE CONTROL
Unit value of the concrete strength under nondestructive control shall be accepted as:
- in case of control of prefabricated constructions (flat and hollow core slabs and covers, road slabs,
panels of interior bearing walls, building blocks, as well as pressure and non-pressure pipes) – average
concrete strength of the construction calculated as the mean strength of controlled areas of the
construction;
- in case of control of other types of constructions – average concrete strength of the construction or a
controlled area or section of the construction, or a section of the monolithic and cast-in-place and precast
construction.