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Re: BOLT- Epoxy Anchors

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In a message dated 10/21/97 12:18:56 PM, you wrote:
Richard Lewis wrote:
<<My question concerns the longevity and proposed application of epoxy
anchors.
 How long are they expected to last.  Specifically, my column is located
outside the building and wrapped in masonry.  It will be exposed to the
seasonal temperature variations of Dallas, TX.  Does normal seasonal
temperature variation affect the anchor bond?  Are there published
limitations to the use of epoxy anchors?
__>>

Most epoxies used for anchoring do not have a problem with longevity, however
each product is different.  Always check the ICBO ES listing for limits on the
products application.  If the temperatures on your project will become
elevated repeatedly over its life, as I suspect in Dallas, make sure you check
the Temperature Sensitivity curve in the ICBO Listing.  Some currently listed
products may lose over 40% of their capacity at 100 F.  Normally, you have to
get really hot (over 250) to do irrepairable damage to the anchor.  Otherwise,
it will return pretty much to full strength.

The Hilti HEA is not an epoxy, and there was some discussion on this list in
the past about the longevity of Ester based systems and the issue of
saponification.  Contact Hilti to get the answer on that one.

As Warren Stewert wrote:
 >Resins
>used, however, are not epoxies in the normal sense of the word, as
>epoxies tend to shrink.  Hilti uses polyester (HBP system) and
>vinylester (HEA system) resins, the later being preferred. 

The above is actually backwards.  Polyesters and vinylesters contain styrene
(sp?) to dilute the resin.  These volatiles evaporate out and cause shrinkage.
Epoxies do not contain any solvents to evaporate out (at least our products).
This is one of the reasons that oversizing of holes in the concrete may or may
not be a big issue, depending on which system you choose.

Howard Silverman, P.E.
Covert Operations, Inc.
Anchoring and Crack injection Systems
www.covertoperations.com