Drilling the holes for post-installed anchors
Drilling the holes for post-installed anchors
(OP)
I've got a project where I am going to put in some post-installed (Hilti) anchors in reinforced concrete. Usually I am worried about them hitting (and damaging/cutting) the re-bar putting them in......but in this case, they've got to go where they've got to go. (And I've checked the footing with these bars cut and it's ok.)
Based on previous experience (and reading through some older threads) it appears going through the re-bar is certainly possible. (Apparently you have to change drill bits.) But what is worrying me based on what I am reading is the time/schedule factor. So my question is: Does it take a great deal of time to get this done? If you need a anchor number and embedment depth: we are talking about a dozen anchors embedded about 24 inches. Thanks.
Based on previous experience (and reading through some older threads) it appears going through the re-bar is certainly possible. (Apparently you have to change drill bits.) But what is worrying me based on what I am reading is the time/schedule factor. So my question is: Does it take a great deal of time to get this done? If you need a anchor number and embedment depth: we are talking about a dozen anchors embedded about 24 inches. Thanks.






RE: Drilling the holes for post-installed anchors
Yes, and it is not practical to rush the process.
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RE: Drilling the holes for post-installed anchors
RE: Drilling the holes for post-installed anchors
Dik
RE: Drilling the holes for post-installed anchors
RE: Drilling the holes for post-installed anchors
Rebar cutter- these typically work best at around 5-600 rpm, with a ROTARY ONLY drill (NON-hammering). These bits often only last 2-3 rebar:
http://www.mytoolstore.com/Relton-RB14-7-8-Rotary-...
RE: Drilling the holes for post-installed anchors
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www.VacuumTubeEra.net
RE: Drilling the holes for post-installed anchors
RE: Drilling the holes for post-installed anchors
RE: Drilling the holes for post-installed anchors
Dik
RE: Drilling the holes for post-installed anchors
Core drills are limited in size, meaning they are usually not small enough to meet manufacturer's recommendations for hole diameter relative to threaded rod diameter, unless you have really large diameter anchors. This leaves you with the option of hammer drilling the concrete and drilling through the rebar with a steel bit. There are carbide bits that supposedly do both, but they are incredibly slow. I have also tried some that would not penetrate the rebar.
If you use coring bits, run a sandblasting wand down the hole to roughen or use a heavy wire brush attached to a drill to roughen.
RE: Drilling the holes for post-installed anchors
To give you an idea on production: We did a repair project in 1999 to a power plant foundation that had 220 core holes x 1-1/2" diameter x 72" deep - we used acid to 'etch' the core hole walls for epoxy bond, then copious amount of water to neutralize the acid solution (then check the pH of the concrete). Production was 220 holes in 21 days (including epoxy work) so about 10 holes per day. 2 core rigs were used, with extendable bits to reach the 6' depth.
I would expect 12 holes x 24" depth x small diameter (depending on access etc) to take 2 days with a 2 man crew, so about 32 (wo)manhours.
RE: Drilling the holes for post-installed anchors
RE: Drilling the holes for post-installed anchors
Hilti claims this adhesive product is better for core drilled holes: https://www.hilti.com/content/hilti/W1/US/en/servi...
There's more info in the "For Installers" button a ways down the page.