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Re: Slab Curl

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> From: Jim Kestner <jkestner(--nospam--at)>

> Slab curl is normally caused by a differential of moisture content
> between the top and bottom surface of the slab. Similar to a wet paper

> Solutions to minimize curling in future slabs are:
> 3 " of stone shavings over the vapor barrier

An interesting alternate:

Concrete International vol 22, #1 Jan 2000
Reducing Shrinkage Cracking and Curling in Slabs-on-Grade

Interesting article describing a method to raise the slab at 7 days to
permit ventilated curing of the underside. Two test slabs (13'x26'x6"
lifted 5" and 48'x26'x7" lifted 3") were raised by inflating
pre-installed airbags (tubes).

Alternately, using the same airbag type tubes, these can be installed in
the slab, inflated before placing and deflated for ventilation within
hours of the pour. The effect is like a hollow core plank. The authors
suggest this technique for elevated slabs as well.

Paul Ransom, P. Eng.
Burlington, Ontario, Canada
<mailto:ad026(--nospam--at)> <>