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Re: New Subject-Testing Dowels/Expansion Bolts

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In a message dated 1/31/98 7:08:41 PM, you wrote:

<<Any suggestions on what percentage of drill-and-bond dowels (or exp. bolts)
installed in the OLD concrete to be specified for testing, and what should the
test load be (in terms of the specified allowable capacity)??. It is possible
that the old concrete might fail (in cone failure) during the test. How can
this situation be handled in the specifications? Any suggestions would be
appreciated.

Suresh
Oakland, CA>>

I have seen testing percentages vary widely from none at all to 100%.
Providing deputy inspection is supposed to eliminate the need for testing
(except for URM) however certain  owners may require/desire additional
testing.  Test loads also vary, but twice the ICBO ES allowable load (50% of
ultimate) seems to be common.  The old concrete shouldn't fail at this load if
the allowable capacity is based on ultimates using the correct test methods.
ASTM and ICBO test methods account for base material strength by not
restraining the substrate during testing.  Therefore, you shouldn't pull a
cone until you reach the rated ultimate capacity.  Just make sure that if your
concrete strength on the job is 2000 psi, that your allowable loads are not
based on 4000 psi.

Howard Silverman, P.E.
Covert Operations, Inc.
Anchoring & Crack Injection Systems
www.covertoperations.com