# Can't get anchor bolts to fully embed in concrete



## Mr_Stop (Aug 15, 2016)

I'm trying to install epoxied anchor bolts/rods into concrete and for the life of me can't get them to fully embed. I have tried it dry and with the epoxy, beating the living snot out of them and they just seem to stop short of where I want to be.

Most recently, I'm using 1/2" galvanized threaded rod. Per the epoxy mfg., instructions I:


Drilled a 9/16" hole in the concrete to the depth I wanted
Blew out the hole with compressed air
Brushed the hole out
Blew out the hole again

When I install the bolt, at some point, it just bottoms out short of my target. I even drilled another 1"+ beyond where I needed to be and it still doesn't go all the way.

Suggestions?


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## META (Apr 9, 2015)

Edit:

Nevermind, you answered my question.


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## griz (Nov 26, 2009)

i dunno....

drill it deeper & hit it harder...:whistling


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## Robie (Feb 25, 2005)

Mr_Stop said:


> I'm trying to install epoxied anchor bolts/rods into concrete and for the life of me can't get them to fully embed. I have tried it dry and with the epoxy, beating the living snot out of them and they just seem to stop short of where I want to be.
> 
> Most recently, I'm using 1/2" galvanized threaded rod. Per the epoxy mfg., instructions I:
> 
> ...


It's your name.

Sorry, couldn't resist.

Dunno.....


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## dayexco (Mar 4, 2006)

threads dry? maybe try a little KY......er...lube


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## Inner10 (Mar 12, 2009)

You probably have dust compacted on the bottom of the hole that didn't evacuate. I use a thin hose on the shop vac but sometimes you really have to agitate it. Scrub, blow, vac, scrub, blow, vac etc. The rod should just drop in dry, and squish in easy with epoxy.

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## Calidecks (Nov 19, 2011)

It's okay to drill or a few inches deeper. Also don't you need a deputy inspector to make sure the holes are clean etc. 


Mike.
_______________


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## META (Apr 9, 2015)

Ok, how deep do you need to go?

I run 1/2-5/8" titan anchors 5-6" deep no problem with 1/2" Milwaukee cordless.

Clear the hole periodically as you bore it, hit depth, clear again a couple times. 

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## Inner10 (Mar 12, 2009)

Calidecks said:


> It's okay to drill or a few inches deeper. Also don't you need a deputy inspector to make sure the holes are clean etc.
> 
> 
> Mike.
> _______________


Recommended method is 2-2-2, brush blow brush.

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## griz (Nov 26, 2009)

Calidecks said:


> It's okay to drill or a few inches deeper. Also don't you need a deputy inspector to make sure the holes are clean etc.
> 
> 
> Mike.
> _______________


In my previous life an inspector checked ALL holes prior to epoxy set.

Then at least 25% were pull tested.


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## Mr_Stop (Aug 15, 2016)

With my current holes, I am trying to go 10" and ended up drilling down to 11"+. I am probably an 1" or so higher than I want to be.


Holes are drilled with a Bosch SDS-plus bit.



It is possible some of the dust got compacted in the bottom. It might be worthwhile to try vacuuming out the holes prior to blowing. I may also try to add an extension to my blow gun that reaches closer to the bottom.


My other option might be to step up my drill bit size to 1/8"-1/4" bigger than the hole.


I'm not in seismic country, so inspections of anchor hole depth and pull testing hasn't been required of me yet.


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## Caleb1989 (May 26, 2018)

Usually do a 5/8 hole for 1/2” AT.

You’ve got to get that junk out of the bottom of those holes. Get a skinny piece of pipe to make the compressed air go all the way down, and wear PPE.

Don’t forget to drill mount your wire brush 


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## META (Apr 9, 2015)

So what tool, or part of the process is exactly failing? 

The 1/2" impact will sheer bolts that have bottomed out...curious if you have enough torque for that depth....or maybe they are sheering off prior to reaching depth?

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## Calidecks (Nov 19, 2011)

META said:


> So what tool, or part of the process is exactly failing?
> 
> The 1/2" impact will sheer bolts that have bottomed out...curious if you have enough torque for that depth....or maybe they are sheering off prior to reaching depth?
> 
> Sent from my SM-N950U using Tapatalk




I think he's using thread rod and he's unable to get them deep enough. I don't think you can drill too deep on most applications, especially footings. 

Edit: as long as you have at least 3" of concrete all around the bolt. 


Mike.
_______________


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## Calidecks (Nov 19, 2011)

I have a piece of clear tubing reduced from a vacuum hose. I find a vacuum works best. 


Mike.
_______________


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## tgeb (Feb 9, 2006)

Bosch makes bits that you can hook up to a vacuum in order to be silica compliant. It pulls the dust out of the bottom of the hole as you drill.

https://www.boschtools.com/us/en/more/news-and-extras/specials/speed-clean/

The only time I have had issues with anchors not setting right, air was getting behind them and the epoxy would seal around the anchor. The air would compress and try to push the anchor out. A few more hits with a hammer usually would correct the problem.


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## tgeb (Feb 9, 2006)

I just re-read your first post. 

A 9/16" hole might be too small for the 1/2" rod. Most likely you are pushing the epoxy to the bottom of the hole, then there is not enough room around the anchor for the epoxy to squirt out around the anchor.

I always use a 5/8" drill for 1/2" anchors.


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## griz (Nov 26, 2009)

tgeb said:


> I just re-read your first post.
> 
> A 9/16" hole might be too small for the 1/2" rod. Most likely you are pushing the epoxy to the bottom of the hole, then there is not enough room around the anchor for the epoxy to squirt out around the anchor.
> 
> I always use a 5/8" drill for 1/2" anchors.


Tom pretty much nailed it.

you have created a hydraulic lock by basically trying to put 10 pounds of chit in a 5 pound bag.

by your posts i'd wager the holes are not adequately cleaned out either.

combo of vacuum and compressed air generally do the trick.

when vacuuming the hole & blowing it out it is imperative that you get to the bottom of the hole.


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## Golden view (Feb 16, 2012)

It is completely imperative that you have an extension on your blower that reaches the bottom of the hole. We will fail a special inspection if we don't do that, and also fail if dust comes out when doing that. The hole must be completely clean.


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## Golden view (Feb 16, 2012)

The other thing I could see is your masonry bit being worn out. But don't drill a larger hole without changing brands of epoxy to something that recommends a larger hole.


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