I would say minimum 70% of 28 day design strength but not less than 2,000 psi.
Martin
From: Ralph Tavares [mailto:ralph@rstavares.com]
Sent: Wednesday, November 30, 2011 9:59 AM
To: <seaint@seaint.org>
Subject: Re: Post Installed Anchors in Young Concrete
You should use the concrete strength at installation of the anchors not at 28 days. So estimate it or rely at the tests, you probably have data. Hilti has values for installations at 2000 psi concrete for this reason.
Thank you
Sent from mobile, please excuse errors and brevity.
Ralph Tavares
R&S Tavares Associates, Inc.
Cell: 209-765-5592
On Nov 30, 2011, at 7:54, "Tom.Hunt@fluor.com" <Tom.Hunt@fluor.com> wrote:
Paul,
I do not have one in front of me, but typically post installed anchors (i.e. Hilti, Redhead, Simpson, etc.) have an ICC Evaluation Report that should have the strength/curing requirements of the base concrete. My guess is that they likely say fully cured which typically means 28 days unless using high/early concrete. Go to the ICC website and down load the applicable ICC ER report.
Thomas Hunt, S.E.
Fluor
From: Paul Blomberg <paul.blomberg@gmail.com>
To: seaint <seaint@seaint.org>
Date: 11/30/2011 07:19 AM
Subject: Post Installed Anchors in Young Concrete
I have a contractor that is casting a small pump pad and five days later wants to drill and epoxy anchor bolts into the pad for the small pump and motor. Does anyone know of any guidance on how much strength or how old the concrete should be before drilling and epoxying?
I don't need the anchors to actually hold their load until later when the rest of the piping is hooked up and by then the concrete will reach it's design strength. I'm more worried about damage to the concrete pad or integrity of the installed anchor when it is installed in green concrete.
I appreciate your thoughts and comments!
Paul.
Phoenix, AZ
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