Result Of Core Test

[Ghulam Abbas Gazer]

Assalam Alaikum

 

              At  Our Project specification for concrete is 3000 psi (cub) We used normal ration 1:2:4 & checked the cube at site the result was ok.What should be the acceptable result of  core test for this to justify this specification the length of core is two time of its diameter we would like to have u reply with complete reference.

 

thanks

[Ayesha]

See the attached document:

ACI 214.4R-03: Guide for Obtaining Cores and Interpreting Compressive Strength Results

ACI_2144r_03.PDF

[zenith.international]

For new constrcution, It is recomended that on sites, instead of cubes, cylinders should be cast. The recommended cylinder size is 4x8 inches. The cylinders cast on site should be cured in the same fashion as the strcutural members. These cylinders should be tested in an accredited lab.

 

For exsisting construction, the scheme and location for coring should be decided, coring should be done by trained professionals and the Interpreting Compressive Strength Results should be completed by a professional engineer (PE).  The results should not be limted only to the strength test, it should also include the stiffness (modulus of elasticity)

[Saiful Islam Zaber]

How to select & eliminate an outliner among a set of core strength ??? ACI Code 214 has an example ..But it's not clear to me. Among  3200 psi ,3500 psi ,2000 psi,3400 psi ,3600 psi,3450 psi  is 2000 psi an outliner ?? How to find mathematically ??

[EngrUzair]

Assalam-o-alaikum!

 

You may need to go through following steps, to reach the conclusion in this regard:

 

1. Calculate standard deviation of concrete strength data, as per ACI 214.4.

 

   a. If you want to learn, how the standard deviation is calculated, you may refer to the following link:

 

https://www.easycalculation.com/statistics/learn-standard-deviation.php

 

b. You may also use 'standard deviation calculator' available at following link, to calculate standard deviation: 

 

https://www.easycalculation.com/statistics/standard-deviation.php

 

2. To determine whether the lowest value is an outlier or not, calculate the the quantity, Q, given below:

 

Q = (Average value of strength data - minimum value of strength data) / Standard deviation

 

3. From what I have understood from the study of ACI 214.4, ASTM E 178 and other sources I came across in this connection, you have to compare the value of Q calculated above, with the value given in Table 1 of ASTM E 178  at the 1.0% significance level for a set of six observations (since you have 6 strength test values).

 

IMO if your calculated Q value is more than than the relevant value given in Table 1 of ASTM E178,  your lowest value would be outlier. (I might be missing something here, as I have not dealt with this subject earlier.  And, therefore would request others to correct me, in case I have faltered somewhere).

 

4. ASTM E 178 may be downloaded from the following link:

 

http://library.sut.ac.th:8080/astm/cd14022005/PDF/E178.pdf

 

HTH

 

 

Regards.

[UmarMakhzumi]

Excellent reply Uzair.

[Saiful Islam Zaber]

1) ACI 214 mentioned E 178-80 for two sided test table 1 But in E 178-02  table 1 is for one sided test 

 

2) Can you give me alink to ASTM E 178-80 ?? That will be greatly appreciated.

 

3)one sided and two sided test are not clear to me ..But it seems here it's a two sided test

 

4)With all the due respect  I  think   your point 3 (2nd para) is Wrong .Say Q= 2 , Say  the value of table 1 for 1% w.r.t  number of observation is 1.80 or 1.90 or 1.95 ,Q >(~) table value So the possibility of having a core like this is about 1 in every 100 ,which is very unlikely ,So can be defined as an Outliner. 

 

[EngrUzair]

Assalam-o-alaikum!

 

1. Yes. You are right.

 

Description of point No. 2, in the table on page 2 of the following link, indicates that due to revision of ASTM E178 (changing the 'two sided' test to 'one sided', among other changes), ACI 214 committee also adopted the 'one sided' test in 2010.

 

http://www.concrete.org/committees/getagendaminutes.aspx?DocID=57664

 

2. It is an old standard. I don't have link for that. The one I knew, was for E 178-02, already given above.

 

3. See answer in para 1 above.

 

4. Since the matter relates to statistical analysis, try consulting some professor to clarify your doubts & the concept. You may wait for the response from other members, if you are not in a hurry.

 

 

Regards.

[Saiful Islam Zaber]

Thanks For Your Response 

 

 

 

Do you have ACI 214-10 ??

 

AND ASTM E 178-08 ?? 

 

Those two Documents Will solve all Problems..

[EngrUzair]

Assalam-o-alaikum!

 

No. You would probably have to contact ACI and ASTM for them. 

 

 

Regards.