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Er. Surya SEFI Member
Joined: 04 Jan 2019 Posts: 3
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Posted: Mon Apr 29, 2019 7:10 am Post subject: Mean of the Group of 4 Non-Overlapping Consecutive Test Results In N/mm^2 |
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Mean of the Group of 4 Non-Overlapping Consecutive
Test Results In N/mm^2
Dear SEFI Forum Members.
Request your kind advice on how to group the average results obtained from mean of 3 cube specimens
say.
CUBE 1 | |
CUBE 2 | AVG SAMPLE 1 |
CUBE 3 | | | |
CUBE 4 | | CUBE 5 | AVG SAMPLE 2 | CUBE 6 | | | |
CUBE 7 | | CUBE 8 | AVG SAMPLE 3 | CUBE 9 | | | |
CUBE 10 | | CUBE 11 | AVG SAMPLE 4 | CUBE 12 | | | | CUBE 13 | | CUBE 14 | AVG SAMPLE 5 | CUBE 15 | | | | CUBE 16 | | CUBE 17 | AVG SAMPLE 6 | CUBE 18 | | | | CUBE 19 | | CUBE 20 | AVG SAMPLE 7 | CUBE 21 | | | | CUBE 22 | | CUBE 23 | AVG SAMPLE 8 | CUBE 24 | |
Now the grouping of AVG SAMPLE will be...HOW?
1st non overlapping AVG SAMPLE (1+2+3+4)
2nd non overlapping AVG SAMPLE (2+3+4+5)
OR
2nd non overlapping AVG SAMPLE (5+6+7+8)
Thanks in advance.
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badamsundararao ...
Joined: 24 Dec 2009 Posts: 218 Location: KAKINADA ANDHRA PRADESH
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Posted: Tue Apr 30, 2019 2:38 am Post subject: AVERAGE |
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To my opinion average is required for set of three only and no need to go for further average.Elders have to confirm this.
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es_jayakumar General Sponsor
Joined: 24 Nov 2011 Posts: 1408 Location: Cochin
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Posted: Tue Apr 30, 2019 2:54 pm Post subject: |
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IS Code 456 : 2000 stipulates :
16 ACCEPTANCE CRITERIA
16.1 Compressive Strength
The concrete shall be deemed to comply with the strength requirements when both the following condition are met:
a) The mean strength determined from any group of four consecutive test results compiles with the appropriate limits in col. 2 of Table 11.
b) Any individual test result complies with the appropriate limits in co1 3 of Table 11.
Going by "any group of four consecutive test results " in the above, the groups (1,2,3,4), (2,3,4,5), (3,4,5,6),....etc. shall hold good.
However, the heading of Col.2 of Table 11 stipulates "Mean of the Group of
4 Non-Overlapping Consecutive Test Results". Here, "Non-overlapping" creates confusion.
Ashok K. Jain, in his book "Reinforced Concrete - Limit State Design", in Example No.2.7.(c), has adopted moving mean of 4 results, ie., (1,2,3,4), (2,3,4,5), (3,4,5,6),....etc.
E S Jayakumar
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es_jayakumar General Sponsor
Joined: 24 Nov 2011 Posts: 1408 Location: Cochin
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Posted: Tue May 14, 2019 1:31 am Post subject: |
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No further comments / clarifications were seen posted here, on this topic. A spread sheet prepared for checking the acceptance criteria as per the Codal provisions (moving mean concept) is attached.
E S Jayakumar
Warning: Make sure you scan the downloaded attachment with updated antivirus tools before opening them. They may contain viruses. Use online scanners here and here to upload downloaded attachment to check for safety.
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Mix Design (Acceptance Criteria) .xls |
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TPS61 SEFI Regulars
Joined: 07 Feb 2011 Posts: 22
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Posted: Wed May 15, 2019 10:29 am Post subject: acceptance criteria for cube strengths |
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The codal clause is quite clear. As stated by Jayakumar, the consecutive groups to be examined are (1,2,3,4), (2,3,4,5),(3,4,5,6) etc.
The average of each of these groups must meet the stated criteria.
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es_jayakumar General Sponsor
Joined: 24 Nov 2011 Posts: 1408 Location: Cochin
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Posted: Fri May 17, 2019 2:21 am Post subject: |
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Sir,
What does the term "non-overlapping" in "Mean of the Group of 4 Non-Overlapping Consecutive Test Results" [Col.2 of Table 11] indicate ? This creates confusion.
E S Jayakumar
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TPS61 SEFI Regulars
Joined: 07 Feb 2011 Posts: 22
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Posted: Fri May 17, 2019 3:29 am Post subject: acceptance criteria for cube strengths |
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I agree, the language is confusing.
I go by Logic which is : "average of any 4 consecutive strength results should...."
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Er. Surya SEFI Member
Joined: 04 Jan 2019 Posts: 3
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Posted: Fri May 24, 2019 12:25 pm Post subject: |
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Dear Members of SEFI
Request your kind views on Explanation of acceptance criteria on page- ( Page - 34,35,36,37,38 ) of SP-24
on page 37 of SP -24 towards the end (a) it states.
if every sample is to the right of C,
accept each of the sample. (see Fig. E-3)
Where when referred C = Fck Characteristic Strength which for M25 would be 25 N/mm^2 after 28 days curing.
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es_jayakumar General Sponsor
Joined: 24 Nov 2011 Posts: 1408 Location: Cochin
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Posted: Tue Jul 30, 2019 2:59 am Post subject: Re: acceptance criteria for cube strengths |
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TPS61 wrote: | The codal clause is quite clear. As stated by Jayakumar, the consecutive groups to be examined are (1,2,3,4), (2,3,4,5),(3,4,5,6) etc.
The average of each of these groups must meet the stated criteria. |
But, Dr.N.Subramanian, in his book on Reinforced Concrete Design (PP-132) says "test result of one group should not be taken in another group too". This stresses on "non-overlapping" requirement.
E S Jayakumar
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es_jayakumar General Sponsor
Joined: 24 Nov 2011 Posts: 1408 Location: Cochin
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Posted: Thu Oct 31, 2019 3:08 am Post subject: |
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es_jayakumar wrote: | IS Code 456 : 2000 stipulates :
16 ACCEPTANCE CRITERIA
16.1 Compressive Strength
The concrete shall be deemed to comply with the strength requirements when both the following condition are met:
a) The mean strength determined from any group of four consecutive test results compiles with the appropriate limits in col. 2 of Table 11.
b) Any individual test result complies with the appropriate limits in co1 3 of Table 11.
Going by "any group of four consecutive test results " in the above, the groups (1,2,3,4), (2,3,4,5), (3,4,5,6),....etc. shall hold good.
However, the heading of Col.2 of Table 11 stipulates "Mean of the Group of
4 Non-Overlapping Consecutive Test Results". Here, "Non-overlapping" creates confusion.
Ashok K. Jain, in his book "Reinforced Concrete - Limit State Design", in Example No.2.7.(c), has adopted moving mean of 4 results, ie., (1,2,3,4), (2,3,4,5), (3,4,5,6),....etc.
E S Jayakumar |
Yesterday, I clarified as per "Correction slip No.1 to IS 456 : 2000" that "non-overlapping" has been added in Cl.16.1 (a) too.
Now it is clear that we have to take the sequence (1,2,3,4), (5,6,7,8 ), (9,10,11,12),....etc. BS EN 206: 2013 permits the use of either, but cautions that in case of adopting overlapping test results, the risk of rejection is more. A work sheet prepared accordingly is enclosed. The previous one posted by me may be discarded.
E S Jayakumar
Warning: Make sure you scan the downloaded attachment with updated antivirus tools before opening them. They may contain viruses. Use online scanners here and here to upload downloaded attachment to check for safety.
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