Strengthening of foundation

[chella123]

I have a situation here where in contractor has poured the footings by draining the water in the pit. However, water table is 3'-0" above the bottom of the footing.

This was not brought to my notice. However, When i formed the core test at 21 days the compressive strength achieved was only 50% of the actual strength. Is there any method to strengthen the footing or should I ask them to demolice and re-do the footing?

Charles

 

[MiketheEngineer]

Recheck your loads - maybe the footing is OK at 50% - maybe not.

If you are at 3'-0'' below the water table - you have a whole lot of new concerns.

See thread in this forum about three below yours by "sfred11"

 

[civilperson]

Concrete placed under water is in the best of cure environments. The placement with tremie or "elephant trunk" chute is a standard proceedure. The results described are possibly due to free fall of plastic concrete onto a muddy subgrade or low quality mix with a shortage of cement. The cores are a good indicator of sub-standard product that needs replacement.