crack on top of the columns

[chekre]

Hi guys,

i have encountered the attached crack in some columns that have been poured 5 days ago. the crack is just at the top of the column which is the bottom of the slab since the column is stopped at the slab soffit.
Despite it is wide, I don't think it will affect the strength of the column. ( maybe due to some vibration problems during casting of the columns).

Any thoughts if i shall take any measures before casting the slab ?

 

[JAE]

Looks like the longitudinal bars were bent to fit to the ties or something and this may have caused the crack.

The column is presumably adequately tied but I would suggest filling such a large crack with epoxy just for safe measure.

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[hokie66]

Plastic shrinkage cracks which could have been closed by revibration, but weren't. Unless there are other issues with the tops of the columns such as horizontal plastic settlement cracks, I wouldn't worry about it.

 

[JAE]

hokie - can you see that it is truly plastic shrinkage by the crack characteristics? I didn't look that close. Do the crack edges roll in or something?



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[hokie66]

JAE,

Sorry I didn't read your post or look closely enough at the photograph before I rashly attributed it to plastic shrinkage. While the cracks do have the general ragged appearance of plastic shrinkage cracks, I agree that all that realignment of bars, probably with some heat as well as brute force, probably caused the cracks.