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Re: Shrinkage cracks in masonry walls

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There is a concrete waterproofing product called "XYPEX" that I have used for
sealing cracks in concrete. It can be applied on old as well as new concrete and,
I think that it can be used on CMU.  The product enters all cracks and kind of
expands to seal them.  Reportedly, color of XYPEX will closely match the parent
material. The headquarter is in Canada (Ph. 604 273 5265).  The company has
representatives in many U.S. states and their representative in Oklahoma City can
be reached at 405 236 2049.  However, please check the phone numbers.

Rajendran

RJConley(--nospam--at)aol.com wrote:

> I have recently inspected a newly constructed single story CMU building and
> have noted shrinkage cracks in the walls below a significant number of
> windows.  Typically there is a crack below the window sill that runs
> vertically (4'-0") from the window sill to the foundation.  The cracks do not
> stair step but have split the face shell of the block at alternate courses.
> The walls are reinforced (#5 @ 32 vert. & #5 @ 40 horiz typ.) solid grouted 8"
> CMU.  After reviewing the design docs, contractor submittals and inspection
> reports I have good idea of why this happened.
>
> My problem is what to do, if anything, to mitigate this visually for the owner
> who lets say is not fully satisfied.  The blocks are a mix of split and smooth
> face colored CMU and the mortar is colored to match.  The mortar could be re-
> pointed but trying to fill the cracks in the face shell probably highlight the
> problem.
>
> This is a dessert environment and the cracks are tight (~1/32") but would
> moisture penetration through these pose a significant problem to the interior
> wall finishes?  There are no planters near the wall so it will not get wetted
> during irrigation of the grass.
>
> Any thoughts of this would be appreciated.
>
> Bob Conley, P.E.
>