R.C Base & column with low unacceptable concrete strength
R.C Base & column with low unacceptable concrete strength
(OP)
Being design engineer for a 3 storey R.C building, I requested concrete cores to be tested for base and column upon suspecting column quality from ground to first floor level. Results were surprising, getting only 50% of specified strength. 2 floors have been built supported by this colum & base.
What procedure can I use for remedial work?
What procedure can I use for remedial work?






RE: R.C Base & column with low unacceptable concrete strength
RE: R.C Base & column with low unacceptable concrete strength
28 day strenth for the project are fine but concrete for structural elements in question might not have been sampled. I suspect concrete not ment for structural elements was just used by General construction staff without consulting their supervisors.
Horizontal cracks developed on the column, concrete is weak, you can cheap it easily using 20mm reinforcement bar. Contractor's staff are not well skilled in building works.
Requesting cores to be tested was just a formality to to justify need for remedial work.
RE: R.C Base & column with low unacceptable concrete strength
RE: R.C Base & column with low unacceptable concrete strength
Should we remove column first lift only (affected part) or remove column full lenth casted ( up to second floor level.
RE: R.C Base & column with low unacceptable concrete strength
If possible, can you post a photo.
hokie
I have been using 25MPa concrete for footing beams and 10MPa concrete for blinding layers.
RE: R.C Base & column with low unacceptable concrete strength
I see no reason to remove concrete other than the low strength portion.
As to the procedure, the hard part is supporting the structure above without overstressing it. In order to remove the footing and column, your ground supports and props will need to be a substantial distance away from the column, yet the beams supporting the structure will need to be close to the column to avoid loading it in an unintended manner. I would preload the supporting beams with jacks to take the full dead load before chipping away the defective concrete.
asixth,
Yes, that is common practice, and I was suggesting the 10 MPa found its way into the footing and column in question.
RE: R.C Base & column with low unacceptable concrete strength
RE: R.C Base & column with low unacceptable concrete strength