Concrete cube testing problems
Concrete cube testing problems
(OP)
I am working on a project in which concrete cube samples were taken. Tests were carried out at 3,7,28 days, the specified strength was 4000psi. Unfortunately the samples were not placed in a water for curing. After crushing samples at 28 days, the strength were much lower that 4000psi. Can the contractor be blamed for producinng concrete below the specified strength. Is there anyway of apply a factor to indicate what the strength would have been in an ideal condition.?





RE: Concrete cube testing problems
If there is any problem with the samples, then move on to some sort of field-testing. You could take cores of the material or use a Schmidt Hammer. In fact as far as I am concerned the samples are only to be used to determine if in situ testing is necessary.
In general if the material is to specification then the owner pays for the tests (and repairs if cores are taken) and if not to spec then the contractor pays for the tests and any necessary remedial action.
Rick Kitson MBA P.Eng
Construction Project Management
From conception to completion
www.kitsonengineering.com
RE: Concrete cube testing problems
Now, one thing to consider is - are the "non-cured" specimens similarly cured to the field? In other words, how good did the contractor cure the structure. If he didn't, then the cubes might be a reflection of the concrete in-place strength. But, of course, this will be fought.
The way I see is for you to request coring be done of the structure to confirm. Now, you will have fun with the translation of cylindrical cores to cube strengths! (See Neville's Book on Properties of Concrete. If you want, I have other data along these lines. But, in general, it is commonly accepted that the core results will not be equivalent to the laboratory specimens. It is usually applied that, given no steel is cored, that the average of three cores must be >85% and no single core less than 75% of the specified strength. Several references out there will give core strength vs time. Even after a year, the core strength will not typically be up to the specified strength.
Hope this helps - if you need some more information, advise us.
RE: Concrete cube testing problems
RE: Concrete cube testing problems
flexural test measures the ability of a beam or slab to resist failure in bending. It is measured by loading unreinforced 150x150 mm concrete beams with a span three times the depth (usually 450mm).
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