Steve wrote:
I have heard that a local cement finisher won't take a job if there is going
to be vapor barrior under the slab. I don't know his reasoning..

I'm not sure of the mechanics/chemistry in cement finishing but I have done
a few jobs in the past and never experienced anything like this..

BTW. the humidity this time of year is around 100% but I'm pouring under a
shed roof.

I mixed my own cement in a 3.5 cu/ft mixer and it was 1 cement, 2 sand and 3
rock (5/8"). I'll admit my mixes were fairly wet (not sloppy wet) since I
was working by myself and didn't want it to set to fast.

Too much water in your mix. Cement doesn't dry, it sets. Idealy the
water you put in is just enough to combine into the dry cement and all be
consumed into the final product with no evaporation. the vapor barrier
and the 100% humidity are things that help keep the water from escaping
from the mix before it can be bound up into the hardened cement.

So, there's nothing you can do short of tearing it all out and startting
over, *but* all may not be lost. Your mix may be taking a long time to
cure and may well cure stronger over the course of a week or month. Wait
and see and next time don't add so much water.



John
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