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RE: Methods of Injection of Cracks in Concrete: Which Is Preferred?

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While I can't speak for William, I can speak to my knowledge of "moving"
vs. "non-moving" cracks.

Some like to refer to them as active cracks versus non-active (or passive)
cracks.  What you describe as your understanding is basic on point.  The
idea of an active or moving crack is that the cause of the crack is still
"active" meaning that the crack will move...that is it will still open and
close.  Typical example of this would be a crack in a sidewalk or wall
that will open and close as the temperature changes.

A non-moving crack is a crack that is no longer active.  It may have been
caused by a one time event (such as a one time occurance of structural
overloading) but no longer moves because the original cause (or other
subsequent events) is no longer present.

As Nels aluded to, the best way to repair a crack is to make sure that the
situation causing the crack is no longer present.  This is another way to
make sure that the crack is a non-moving crack.  If the crack is still
moving/active, then the repair may not do too much.

HTH,

Scott
Ypsilanti, MI


On Sat, 9 Feb 2002, Bill Polhemus wrote:

> By "moving" vs. "non-moving" cracks I assume you mean cracks that are caused
> by movement of the structure as opposed to cracks caused by overloading of
> the structure or elements thereof. Am I reading you correctly?
>
> The structure I'm dealing with is not a water containment structure. The
> cracks I'm dealing with are almost certainly from environmental
> deterioration of the concrete over time (the structure in question was built
> in the mid-1960s).
>
>
>
> William L. Polhemus, Jr. P.E.
> Polhemus Engineering Company
> Katy, TX, USA
> Phone (281) 492-2251
> FAX (281) 492-8203
> email bill(--nospam--at)polhemus.cc
>
> -----Original Message-----
> From: Sherman, William [mailto:ShermanWC(--nospam--at)cdm.com]
> Sent: Saturday, February 09, 2002 5:49 PM
> To: 'seaint(--nospam--at)seaint.org'
> Subject: RE: Methods of Injection of Cracks in Concrete: Which Is Preferred?
>
> Are you talking about a liquid containing structure or just general weather
> exposure?
>
> For a liquid containing structure, I would not allow a surface sealant in
> lieu of crack injection. I use polyurethane injection for shrinkage/ moving
> cracks and epoxy injection for structural/ non-moving cracks.
>
> > -----Original Message-----
> > From: Bill Polhemus [mailto:bill(--nospam--at)polhemus.cc]
> > Sent: Saturday, February 09, 2002 1:50 PM
> > To: seaint(--nospam--at)seaint.org
> > Subject: Q: Methods of Injection of Cracks in Concrete: Which Is
> > Preferred?
> >
> >
> > As I believe I've mentioned before, I find myself more and more doing
> > consulting for concrete structure renovations. I have some
> > questions for
> > those who might have some experience with this (especially the plant
> > engineering people, where you're having to use innovative
> > methods using
> > technology beyond "spit and bailing wire" to maintain tank
> > foundations,
> > etc.)
> >
> > My client sent out an Invitation to Bid based on some
> > specifications I had
> > written. Since I'm more comfortable in the world of crack
> > injection using
> > epoxy or urethane, that's the way I went with my spec.
> > However, one bidder
> > replied with an alternate system including "chasing" or
> > "routing out" the
> > cracks, applying a Sonneborn 733 Primer in the routed crack, and then
> > Sonneborn NP2 Sealant. Now, I have used NP2 before, but only
> > as the final
> > component of a joint seal. It has essentially no structural properties
> > (though to be sure the urethane isn't exactly holding up the
> > world). My
> > feeling is that the crack injection is more sure, but the
> > bidder disagrees,
> > saying it is too expensive for the results you get
> > (unbeknownst to him,
> > though, his argument is somewhat overshadowed by the fact that the
> > next-lowest bidder, only 8% higher than the lowest bid, DID submit my
> > procedure to the letter).
> >
> > I'd love to hear input from those who have an opinion and any
> > other wisdom
> > you'd care to share on this topic.
> >
> >
> >
> > William L. Polhemus, Jr. P.E.
> > Polhemus Engineering Company
> > Katy, TX, USA
> > Phone (281) 492-2251
> > FAX (281) 492-8203
> > email bill(--nospam--at)polhemus.cc
> >
> >
> >
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