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Re: Concrete Crack Repair

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Michael,
 
        Concrete is assumed to be cracked, therefore, as long as there is bearing across the crack you should have all the strength you need.  If you're considering the Whitney stress block for your analysis and have a low steel ratio (I think you will have a low steel ratio for mid height of a retaining wall) the actual required bearing area of the concrete will also be small.
 
        I think your greatest concern will be protecting the reinforcing from corrosion at the point of the crack.  You may want to apply a patch over the crack on the back side of the wall as an added protection against this.
 
Regards,
 
H. Daryl Richardson
----- Original Message -----
Sent: Friday, May 11, 2012 9:45 AM
Subject: RE: Concrete Crack Repair

Thanks Harold for the help. The crack is approximately 3/16" wide at the surface and runs horizontally. How do I take the crack into account for purposes of justifying what ever strength remains?
 
Michel
-----Original Message-----
From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com]
Sent: Thursday, May 10, 2012 3:32 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Concrete Crack Repair

Michel,
 
I would suggest epoxy injection.  There are established procedures for epoxy injection.  The crack should be drilled and ported and sealed at the surface.   The injection starts at the bottom and is injected until epoxy comes out of the next port higher.  The injection port is sealed and the gun is connected to the next port higher.  The process is repeated until you get to the top of the wall. 
 
I generally prefer the Sika line of concrete repair products, because they train the workers installing the product and they have good field support. 
 
That said; what is the crack like?  If it is straight vertical, the crack would not impair the structural capacity.  If it is diagonal, it COULD impair the strength of the wall.  If it is horizontal it WOULD impair the strength of the wall, but not by too much given the size and due to the fact it is a retaining wall.  Crack injection runs about $7 to $14 per lineal foot. 

Regards, Harold Sprague
 
> From: mblangy(--nospam--at)satco-inc.com
> To: seaint(--nospam--at)seaint.org
> Subject: Concrete Crack Repair
> Date: Thu, 10 May 2012 09:43:24 -0700
>
> List,
>
> I'm looking for suggestions on methods of repairing a through crack in the
> stem portion of a 6-foot long slot segment of a cantilevered concrete
> retaining wall. The 1/8-3/16" wide crack extends the full length at about
> mid-height and was caused by an impact near the top from a ginormous
> bulldozer on the toe side.
>
> Thanks,
>
> ----------------------
> Michel Blangy, P.E.
>
>
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