Concrete results are evaluated according to the TS 500 / February 2000 and TS EN 2061 Standards.
1  Evaluation according to TS 500 / February 2000 Standard
Evaluation of concrete compressive strength results are based on the values of 28 days. The samples which are taken three at a time, are organized as; G_{1}, G_{2}, G_{3 }………. Gn according to their collection rank. The parties which come one after the other
P_{1 } ( G_{1}, G_{2}, G_{3} ) , P_{2} ( G_{2}, G_{3}, G_{4} ) , P_{3} ( G_{3}, G_{4},G_{5} ) ,……..P _{n2 }
are evaluated according to the conditions below.
a) Average compressive strength for each party
fcm ≥ fck +1,0 MPa ( N/mm^{2} )
fcm = Average strength
fck = Characteristic strength ( project strength )
b) Minimum group average compressive strength in each party
fcmin ≥ fck – 3,0 MPa ( N/mm^{2} )
The concretes of the parties which applies both of the conditions that are stated above are accepted.
Numerical Example Project strength fck : C20 / 25 

P 
G 
28 Days N/mm2 
Group
N/mm2

Party Average N/mm2

Minimum group average of the Party N/mm2 
Evaluation 
RESULT 
P1 
G1 
242525 
24.6 
25.6 
24.6 
fcm = 25.6 < 25+1 
Rejected 
G2 
252724 
25.3 

G3 
282726 
27.0 

P2 
G2 
252724 
25.3 
26.8 
25.3 
fcm = 26.8 > 25+1 
Accepted 
G3 
282726 
27.0 

G4 
292828 
28.3 

P3 
G3 
282726 
27.0 
28.1 
27.0 
fcm = 28.1 > 25+1 
Accepted 
G4 
292828 
28.3 

G5 
302829 
29.0 
2  Evaluation according to TS EN 2061 Standard.
Samples whose conformity of concrete compressive strength are applied to the 28 days test, are evaluated according to the conditions below.
Chart 14  Conformity Criterias for Compressive Strength TS EN 2061 / April 2002 

PRODUCT 
Number produced in the Group after the pressure strength test "n" 
1. Criteria 
2. Criteria 
"n" number test result average ( fcm) 
Any single test result ( fci) 

Start 
3 
≥ fck + 4 
≥ fck  4 
Constant 
15 
≥ fck + 1.48 . σ 
≥ fck  4 
Chart 15 – Confirmation Criterias of the Members Belonging to the Group TS EN 2061 / April 2002 
Test Result Number for Single concrete compound  "n" 
3. Criteria 
"n" number test result average for a member of the group  fcm 

2 
≥ fck  1.0 
3 
≥ fck + 1.0 
4 
≥ fck + 2.0 
5 
≥ fck + 2.5 
6 
≥ fck + 3.0 
In the Chart 14 1st Criteria, “n” number of overlapping or not overlapping consecutive test result group – fcm
2nd Criteria, single test result – fci
Conformity is approved by providing those both criterias above.
If the conformity, will be evaluated for the concrete group;
All converted test results which belong to the 1st criteria group will be taken into consideration and applied to the refered concrete.
And 2nd criteria is applied to the original test results.
In order for a concrete to be approved that it belongs to a group, all of the average of test results which aren’t converted belonging to that concrete ( fcm) must be evaluated according to the 3rd criteria which is given in chart 15. Any concrete which doesn’t apply this criteria, is not accepted in the group and independently evaluated for it’s conformity.
In the 1st criteria the coefficient 1,48 in characteristic strength concept, expresses the value of % 5 which is the possibility of getting lesser values than itself . If this coefficient is above TS 500/2000, it will mean that the objective concrete will stay in the safer side, and this will effect the performance of the concrete beneficially.
In the beginning, the standard deviation of at least 35 test results in 3 months time period must be calculated before the production period. This value is taken as the estimated standard deviation for the whole production. The standard deviation along with the production whose conformity control will be checked, is determined in the beginning will be stated as valid on condition that (S15) standard deviation applies to the “ 0,63.σ ≤ S15 ≤ 1,37. σ “ . If S15 is outside these limitation of values, the latest 35 test results of the consecutive production will be used in order to calculate a new standard deviation value.
Numerical Example Project strength : C 20/25 

Group  15x15x15 cm Cube Strength N/mm2

Average Strength 
Minimum Single Value 
Evaluation 
Result 
1  26  28  29 
27.6 
26 
27.6 < 25.0+4.0 
Rejected 
2  24  25  26 
25.0 
24 
25.0 < 25.0+4.0 
Rejected 
3  28  30  30 
29.3 
28 
29.3 > 25.0+4.0 
Accepted 
4  29  28  27 
28.0 
27 
28.0 < 25.0+ 4.0 
Rejected 
5  30  29  31 
30.0 
29 
30.0 > 25.0+4.0 
Accepted 
All Production 
Average Strength fcm =28 Standard Deviation (σ) = 1.5

28.0 
24 
fcm≥fck+1.48x σ 
Accepted 
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