www.sefindia.org

STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

 Forum SubscriptionsSubscriptions DigestDigest Preferences   FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups  RegisterRegister FAQSecurity Tips FAQDonate
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log in to websiteLog in to websiteLog in to websiteLog in to forum 
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.

ACCEPTANCE CRITERIA OF CONCRETE
Goto page Previous  1, 2, 3 ... 9, 10, 11
 
Post new topicReply to topic Thank Post    www.sefindia.org Forum Index -> SEFI General Discussion
View previous topic :: View next topic  
Author Message
bijay sarkar
...
...


Joined: 14 Dec 2009
Posts: 314

PostPosted: Thu Apr 05, 2012 5:24 pm    Post subject: Reply with quote

Some clarifications on acceptance criteria of concrete as available in net.


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.
clarification-on-acceptance-criteria-as-per-is-456.pdf
 Description:
Acceptance Criteria

Download
 Filename:  clarification-on-acceptance-criteria-as-per-is-456.pdf
 Filesize:  307.01 KB
 Downloaded:  345 Time(s)

Back to top
View user's profile Send private message
sspawar
...
...


Joined: 05 Jun 2009
Posts: 1171

PostPosted: Thu Apr 05, 2012 11:21 pm    Post subject: Reply with quote

Regarding Batch and sampling , follow IS1199 below causes:
Hope this will make clear all doubts.

3. SAMPLING OF FRESH CONCRETE IN THE PIELD
3.1 This method specifies the procedure to be followed in the field for
obtaining representative samples of fresh concrete directly Coti the mixer
or from concrete at the time and place of depositipn.
3.2 Sample - The composite sample shall be truly representative of the
batch and shall be not less than CO2 ma in volume. It shall be composed
of a mixture of portions taken Corn d&rent points in the batch. When
continuous mixers~ are used, batch shall be regarded as the discharge
* from the mixture during one minute.
4.3 Procednfe
3.3.1 From Mixers -At least three approximately equal sample incre_
ments totalling 0.02 ms shall be taken Corn a batch during its discharge
and each sample increment shall be collected l$ passing a clean and
dry receptacle across the stream d concrete. This receptacle shall be constructed
of non-absorbent material, preferably of metal and shall be such
that the sample retained is not segregated. A fiat surface without retaining
sides will not fulfil this purpose. Where three sample increments are
taken they shall be taken at about the time when one-quarter, one-halfand
three-quarters of the concrete have been discharged from the mixer and if
more than three are taken they shall be at correspondingly shorter, but
equally spaced, intervals.
3.3.2 From Concrete at k %ne and Place of Deposition-The sample
shall be taken while a batch of concrete is being, or immediately after it
has been, discharged on the site. The sample shall be collected from not
less than five weli-distributed positions, avoiding the edge of the mass
where segregation may have occurred.
3.4 Mixing the Composite Sample - The composite sample obtained
by either of the methods described above, shall be mixed on a non-absorbent
base either with a shovel or by other-suitable implement in such a
manner as to ensure uniformity. The sample thus obtained shall be used
immediatciy for the purpose of carrying out the tats. Care ~hd be taken
to protect the sample from the weather.

Regards
bijay sarkar wrote:
Some clarifications on acceptance criteria of concrete as available in net.
Back to top
View user's profile Send private message
bijay sarkar
...
...


Joined: 14 Dec 2009
Posts: 314

PostPosted: Sat Apr 07, 2012 3:26 am    Post subject: Reply with quote

Dear Sefians,

Followings are still required :

A.    +-15% Criteria for cube strengths ::::
Clause 15.4  :  "The individual variation should not be more than +15 percent of the average. If more, the test results of the sample are invalid."

What does the above clause indicate to say the test results of the sample are invalid.  

Invalid for what ?  

1.  Does it express that concrete is not acceptable?

2.  If all the cube strengths are much on the higher side of Fck, what is the fate of this concrete?

3.  Does it express that the cube strengths of all the three cubes will not be considered for calculation only?

4.  If these three cubes are not considered in the calculation of SD etc, then whether the balance cubes will be rearranged serially to have a consecutive & non-overlapping test strengths?

B : For STR Criteria in Col 3 & Minm. Mean of Four Samples in Col 2 of Table 11 :::::
1.  If 1 or more sample/samples are not satisfying ITR Criteria, whether the failed sample still is to be considered for calculation of SD, Mean Strength etc? Question remains valid if all the samples of the Set is under risk ?


2.  If single sample which has failed in ITR criteria, what will be fate of other samples of the Set?

3. If a set is OK in ITR criteria but fails in Col 2 criteria, will it still be continued in the calculations?

4.  Whether there is any circumstances when the strength results will be rearranged and calculation is to be started afresh?????????


with regards,

bijay sarkar
Back to top
View user's profile Send private message
sspawar
...
...


Joined: 05 Jun 2009
Posts: 1171

PostPosted: Sat Apr 07, 2012 5:50 am    Post subject: Reply with quote

Dear BIJAY SARKAR
Please find answers below questions written.
bijay sarkar wrote:
Dear Sefians,

Followings are still required :

A.    +-15% Criteria for cube strengths ::::
Clause 15.4  :  "The individual variation should not be more than +15 percent of the average. If more, the test results of the sample are invalid."

What does the above clause indicate to say the test results of the sample are invalid.  

Invalid for what ?  

1.  Does it express that concrete is not acceptable?
Ans: For sample preparation only, that sample/samples will be invalid. Process of sample selection is not carried out properly. Data Sampling should not be fit to the method of Normal distribution curve.

2.  If all the cube strengths are much on the higher side of Fck, what is the fate of this concrete?
Ans: above answer.

3.  Does it express that the cube strengths of all the three cubes will not be considered for calculation only?
Ans:Yes

4.  If these three cubes are not considered in the calculation of SD etc, then whether the balance cubes will be rearranged serially to have a consecutive & non-overlapping test strengths?
Ans: During  acceptance criterion  or SD establishment process these specimens will be ignored as null and void.

B : For STR Criteria in Col 3 & Minm. Mean of Four Samples in Col 2 of Table 11 :::::
1.  If 1 or more sample/samples are not satisfying ITR Criteria, whether the failed sample still is to be considered for calculation of SD, Mean Strength etc? Question remains valid if all the samples of the Set is under risk ?

Ans: In process of SD/TMS/Design Mix establishment clause 15 will be applicable while clause 16 is only for Acceptance criterion processes.

2.  If single sample which has failed in ITR criteria, what will be fate of other samples of the Set?
Ans: An amount of concrete which is represented by that 4 sets of samples, shall be deemed to not acceptable.

3. If a set is OK in ITR criteria but fails in Col 2 criteria, will it still be continued in the calculations?
Ans: Same as above

4.  Whether there is any circumstances when the strength results will be rearranged and calculation is to be started afresh?????????
Ans: Rearranging  is impossible and invalid.

with regards,

bijay sarkar
Back to top
View user's profile Send private message
Ghanashyam
SEFI Member
SEFI Member


Joined: 18 Mar 2011
Posts: 2

PostPosted: Wed Feb 06, 2019 4:29 am    Post subject: Reply with quote

Respected All,

What is the interpretation of " 4 non overlapping consecutive"  in the acceptance criteria for compressive strength test.

For example, if we have a concrete volume of 101 m3 and we have obtained 6 samples (3 specimens for a sample) in order sample-1, 2, 3, 4, 5 , & 6. Then is it correct to take the mean of 4 non overlapping as :

average of samples: 1,2,3,4
average of samples: 2,3,4,5
average of samples: 3,4,5,6
  
and what is non overlapping means in the above?
Back to top
View user's profile Send private message
es_jayakumar
General Sponsor
General Sponsor


Joined: 24 Nov 2011
Posts: 1205
Location: Cochin

PostPosted: Wed Feb 06, 2019 3:55 pm    Post subject: Reply with quote

I hope yes. Please see the attached Spread Sheet :

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.
Mix Design( Acceptance Criteria).xls
 Description:

Download
 Filename:  Mix Design( Acceptance Criteria).xls
 Filesize:  33 KB
 Downloaded:  55 Time(s)

Back to top
View user's profile Send private message
Display posts from previous:   
Post new topicReply to topic Thank Post    www.sefindia.org Forum Index -> SEFI General Discussion All times are GMT
Goto page Previous  1, 2, 3 ... 9, 10, 11
Page 11 of 11

 

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


© 2003, 2008 SEFINDIA, Indian Domain Registration
Publishing or acceptance of an advertisement is neither a guarantee nor endorsement of the advertiser's product or service. advertisement policy