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Re: Capillary Breaks

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In a message dated 2/9/2005 6:18:52 PM Eastern Standard Time, RLHess(--nospam--at)HessEng.com writes:
The granular material between the vapor barrier and the concrete is there to allow water to escape from the bottom of the slab for curing.  If the concrete is placed on the plastic sheeting the top will cure faster than the bottom causing uneven shrinkage and the tendency for curling up of the edges of the slab and resulting cracking at the surface.
 
That is true.  However,  you will find that ACI 302/360 currently recommends that a granular material be used on top of a vapor retarder in only very limited cases.  NRMCA has the same recommendation because they just lifted the section out of ACI 302.
 
But my question is not about granular fills,  it is about capillary breaks.
 
Gail Kelley