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Flooring Failure in Slab on Ground

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List,
I have a friend and sometime client who has a client who has a problem.
They are dealing with a floor slab in a 30 year old building.  The
building was built in a low area.  It apparently has a history of
problems with floor finishes shedding off.

They recently tried a 3 part system: a penetrating sealer, then two
coats of epoxy, roughened between applications.  In most of the building
it seems to be working, but in one 20 x 30 foot area it has developed
blisters and wrinkles.  When they lance the blisters, water comes out.
Surprise.

But, they then decided to cut a sump in the area, and the fill wasn't
found to be wet.  Damp, maybe, but not wet.  The surprising thing (at
least to me) is that the epoxy bond didn't fail--it pulled up concrete
when it blistered.  So, my question:  how much actual pressure is there
in vapor pressure?  I'm not used to thinking about this in terms of
force, but it's splitting concrete.

Is this as unusual as it seems?

Thanks,

Mike Hemstad, P.E.
TKDA
St. Paul, Minnesota

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