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Concrete Sampling for Compressive Strength

Concrete Sampling for Compressive Strength

Concrete Sampling for Compressive Strength

(OP)
According to ACI and ASTM new/ revised standards on concrete sampling/ or testing, concrete sampling can be tested by using 4” * 8” cylinders instead of 6” * 12” to find the compressive strength of the concrete. According to my understanding, instead of 6” * 12” with 2 cylinders for 28 days break, we have to sample 3 cylinders with 4“ * 8”.

If this is correct as per the new standard version, I appreciate if someone can let me know the standard number/ or spec.

Thank you     

RE: Concrete Sampling for Compressive Strength

that will be the new standard according to ibc. as far as i am aware, ibc still references the 03a version of the astm where it states something like "4x8 inch where approved". the 06 version of that same standard removes the "where approved" verbage so that is either/or.

see http://www.eng-tips.com/viewthread.cfm?qid=192291&page=1

RE: Concrete Sampling for Compressive Strength

OK - so here's a follow-up question.  

The ACI 318-05 doesn't mention size of cylinders directly but references:

ASTM C172-04 (Method of Sampling)
ASTM C31-03a  (Making test specimens)
ASTM C39-03  (Testing for compressive strength)

With the current IBC 2006 referencing ACI 318-05, and this ACI 318 referencing these earlier standards (which don't allow 4" cylinders), then technically any new ASTM standard allowing 4" diameter cylinders are not approved by the city or other jurisdiction which approved the IBC 2006.  Right?

RE: Concrete Sampling for Compressive Strength

i believe my response would be "yes, you are correct". 4" cylinders are allowed but should be "approved" by the structural engineer. once C31-06 takes effect in the new code version/supplement, either size will be acceptable unless specifically called out in the project documents. so as of this very minute, the EOR should be the one to approve the use of 4x8 cylinders.

i suspect that the supplement to come out this year will adopt the newest version of C31 but there's no telling when that might actually come out (i suspect near spring time but that's purely a guess).

RE: Concrete Sampling for Compressive Strength

(OP)
Thank you for the remarks!!
According to the changes to expect in the 2008 edition of the ACI building code (ACI 318-08) in chapter 5, the Code has adopted to use of three 4” x 8” cylinders as equivalent to the use of two 6” x 12” cylinders for determining compressive strength.(CI Journal July,2007)

Did anybody knows that this new ACI 318-08 is available in the store?   

RE: Concrete Sampling for Compressive Strength

I think it is coming this year (I've heard February but you never know till it is out)

RE: Concrete Sampling for Compressive Strength

i wouldn't call aci "the building code"...i think calling it "building code requirements" is more appropriate (there is a subtle difference). and until IBC accepts the most recent version, then in my opinion, it's not correct to call it the current standard. until the IBC adoption occurs (should be coming soon) i'll just continue to ask the structural engineer if the 4x8 cylinders are acceptable. i have seen some structural engineers specifically prohibit 4x8 cylinders in their specifications.

RE: Concrete Sampling for Compressive Strength

(OP)
WannabeEIT:
Thank you so much for your information.

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