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Re: Slab on grade Crack repairs

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In a message dated 3/3/2003 3:38:14 PM Eastern Standard Time, enajjarine(--nospam--at) writes:


I have a case of a long crack in a Post tensioned Slab with water leakage
through it. they've used epoxy on it, it didn't work, any ideas for
permanent repair.

This doesn't appear addressed to me, but I will answer it anyway.

When you have a moving crack,  epoxy generally wouldn't work.  In most cases, you just get cracking adjacent to the original crack.  Typically, you rout and seal with a flexible urethane.  There are at least a half dozen Sika and Masterbuilder products that will work.  Water-catalyzed urethanes (hydrophic and hydrophilic expanding urethanes) are generally not used though - they are good in walls but are not really durable enough for slabs.

If it is a newly constructed slab, you will want to wait about two years so that most of the shrinkage has occurred.  If water leakage is a concern during this time,  the easiest thing to do is just apply an elastomeric membrane along the crack, extending 6 in. either side of the crack.

No repair is  permanent though - all crack sealants need to be periodically inspected and replaced.

Gail S. Kelley, P.E.