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Re: Masonry: Epoxy-injection for shear repair?

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Michael:

It's probably a mixed bag, that is, there are lots of micro-cracks,
or cracks that opened and then closed again, plus yielded shear steel.
Epoxy depends entirely on preparation, and since cracks can't be
prepared, and may have been open for a decade oxidizing before the
repair attempt, you can't predict reliable performance. Epoxy anchors,
on the other hand, are set in fresh, cleaned, carbide-cut matrix, with
a mixture of epoxy gel and prismatic ceramic beads to assist in "bite".

Now THAT's a structural connection!

Best bet, look at crack-epoxy as a cosmetic repair and leave it at that.

At 04:46 PM 8/25/97 -0700, you wrote:
>I'm evaluating a 10-story masonry apartment building built in the early
>70's where the walls sustained cracking from both the Loma Prieta
>earthquake and differential settlement.  About 5 years ago, it was
>"repaired" using epoxy injection.  I'm trying to track down which
>product was used without much success.  Apparently the criterion was to
>fix all cracks you could stick a credit card into and call the rest
>"cosmetic".
>My question:  Are these epoxy injection methods effective for restoring
>shear capacity of masonry walls?
>I've talked to some manufacturers who say it is great, stronger than the
>surrounding masonry, etc. but who were not forthcoming with test data.
>A colleague of mine suggests that for every crack, there are many more
>micro-cracks just waiting to open up nearby.  And where there is a
>visible crack, the steel may have yielded, reducing the capacity of the
>wall if steel was used to resist shear.
>Does anyone have any opinions/data on this method of repair?
>
>Michael Livingston, SE
>michael.livingston(--nospam--at)intres.com
>
>
>
>
Regards,
Robert Marmaduke PE
POB 28995, Bellingham, WA 98228
360.738.0854 VOX/FAX
avi(--nospam--at)az.com    http://www.az.com/~avi