I recently discovered a problem with my new deck's foundation and was
hoping
you folks might have some advice on how to proceed.

Last year, I built a conventional 22' x 14' x 2'high single level deck. I
hired a local company to drill and fill with concrete the eight posts I
required for the foundation.

This year, I noticed that 5 of the 8 posts are disintegrating. The
concrete
is was clearly not mixed correctly and can be easily broken apart with a
screwdriver. The remaining three posts appear to be OK. The posts extend
four feet under ground level and about 2 inches above ground level.

I am attempting to get the original company that drilled and set the posts
to fix the problem, but what they are proposing doesn't sound like a
solution to me. They want to put a layer of hydraulic cement around the
tops
of the post to prevent further decay.

I was wondering if anyone had any ideas on what could be done to salvage
the
project?

I don't think setting wood posts in concrete meets code in my area. You're
supposed to sink a concrete pier below the frost line (4' here), and embed a
bolt in the concrete. Then bolt a bracket on top of the concrete to accept
the 4 or 6 by post. So no wood, PT or not, is ever below grade. Eventually
it will rot below grade, PT or not.