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Concrete Anchors Not Grabbing - Fix with Epoxy or ?

desertPOS

desertPOS

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Refurbished an old two post lift, got it installed, used 3/4" anchors to mount it to the slab. Rotary 9k lb lift spec'd out that size anchor with minimum 3-1/4" deep in the slab. Being that it's a 6" slab of high psi concrete, I got 5-1/2" anchors (probably should have got longer, but we already had a handful of that size so I just matched that). Once we got everything drilled, anchors in and tightened to hand tight to check angles on the uprights to see what shims were needed - noticed a handful of the anchors looked like they're sticking up out of the slab a lot higher than they should.

About half the anchors meet the 3-1/4" depth requirement, the other half do not. Pictured below is the second to worst anchor, which is only 2-1/2" deep in the slab. In retrospect, when drilling, the first few inches was all fine, powdery fine concrete dust as you'd expect - but as it got deeper it got much easier to drill and bit was kicking out a very course, granular mixture. Like there's a layer where it didn't cure right or some kind of soft spot.

So, first pic shows the anchor at the height that it gets up to torque, leaving only 2.5" in the slab - just pulled the nut off before I took the pic. Second pic shows depth of the hole if I tap the anchor back down:

IMG_9779.jpeg
IMG_9780.jpeg


It's just too soft for the locking collar to grab anything down there apparently. My best idea is to throw the mag drill on there and drill 1/4" hole through the steel where the blue sharpie circle is - right next to the 3/4 hole so that I can then drill the rest of the way down with same size concrete bit. Into the existing 3/4 hole. Then rig up the shop vac to slurp out as much debris as possible. With the anchor held up to it's highest point, should be enough room in there to inject epoxy down under the anchor, then press the concrete anchor down until the epoxy is squeezing out - let cure, then torque? Then profit?

Never used epoxy before, thought it'd be worth posting my idea here in case there are any good suggestions for any alternatives, or at least what type of epoxy to get. In before the retards chime it with needing to cut the whole slab apart and repour/reinstall:flipoff2:
 
We use epoxy with the sleeves when we can't use expansion. I rarely see over 6" in on walls or to hang off of. Cant imagine under 3 would matter on your load. I'd love to know why not though, we are always pulling on or bracing failing conrete though. If you want to get your head talked off about it call hilti lol
 
slide hammer and yeet that effer up to get the slidey bits to set?

beings we are ignoring all the safety red flags, you mind posting up your location so we can decide who gets your lift when it falls over due to failing concrete?
 
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desertPOS said:
With the anchor held up to it's highest point, should be enough room in there to inject epoxy down under the anchor, then press the concrete anchor down until the epoxy is squeezing out - let cure, then torque? Then profit?
Click to expand...
Sounds like a good plan to me. I'd be a little worried about the sleeve still not grabbing and the epoxy being the only thing holding anything in the hole though. But not worried enough to not do it. :laughing:

Also, vac sucks for getting dust out. Use a blow gun and shop air.
 
Re-reading it....

Since half the anchors don't meet the depth requirement you should probably just pull the lift off and use different anchors.

Maybe step up in size to whatever redhead or tapcon fits the hole you drilled.
 
I might have been doing it wrong, but we have 5 lifts and nothing has failed yet. I drill completely thru the concrete, then put my anchors in. Our concrete is 6" so I use 8" anchors.
 
I've got less concern about anchor and type and much more about the concrete conditions.

Epoxy is a solution but only if the concrete isn't total trash. I'd try that first, set them to 5". Clean clean clean the holes, air gun and brush. If you can tighten to spec I think it will be fine.
 
Maybe try something like this.
factorydirectsupplyonline.com

Simpson EZAC37434 3/8" x 4-3/4" Easy-Set Pin Drive Expansion Anchor

The EZAC easy-set anchor is a pin-drive expansion anchor for medium- and heavy-duty fastening applications into concrete. The EZAC anchor provides holding power in concrete base materials including both concrete masonry unit (CMU) and brick. The anchor includes an integrated nut and washer for...
factorydirectsupplyonline.com factorydirectsupplyonline.com
 
desertPOS said:
About half the anchors meet the 3-1/4" depth requirement, the other half do not. Pictured below is the second to worst anchor, which is only 2-1/2" deep in the slab. In retrospect, when drilling, the first few inches was all fine, powdery fine concrete dust as you'd expect - but as it got deeper it got much easier to drill and bit was kicking out a very course, granular mixture. Like there's a layer where it didn't cure right or some kind of soft spot.
Click to expand...
I'm sure more than a few people will call me a pussy, or tell me to fuck off to garage journal, but it sounds like your concrete is shit, or at least less than ideal.

It would be in the back of my mind for the rest of my life wondering when that thing's gonna fall over, even though lots of hoists have been installed on questionable concrete and most didn't fall over. I'm not an expert on anything, so I tend to be conservative and overbuild so it looks right.

I had to say it.
 
It's common for some blow-out on the underside of the slab when drilling. You probably are in a spot where your 6" slab is closer to 5", and now you're excavating the underlying fill.

How much steel is in your slab? Maybe you want to consider cutting open the slab for the one column and doing a smaller section of what's in post #4.
 
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What if you weld a plate off the side of lift base. Then put another mount hole or two. It would give me a better feeling. Just 6” further out with two more bolts would be dramatically stronger.
 
I have installed a bunch of lifts and no way i would trust your situation. I would try again in a different spot or break it up and repour a section. Or maybe break the rules and drill all the way through and try a longer anchor.

Btw, when I install I drill, then use a shop vac with a thin tube to suck the dust out. then a blow gun to get the rest out. Then the 2 part concrete epoxy they sell at fastenal. A little in the hole then coat the anchor in it. Knock the anchor into depth and tighten the anchor with a cordless impact and then torque to spec.
 
Muckin_Slusher said:
I'm sure more than a few people will call me a pussy, or tell me to fuck off to garage journal, but it sounds like your concrete is shit, or at least less than ideal.

It would be in the back of my mind for the rest of my life wondering when that thing's gonna fall over, even though lots of hoists have been installed on questionable concrete and most didn't fall over. I'm not an expert on anything, so I tend to be conservative and overbuild so it looks right.

I had to say it.
Click to expand...
post 3
we are ignoring red flags
try to keep up :flipoff2:
 
Cut the concrete out, re pour. Have anchor bolts that will hold.
 
I wouldn’t trust my life under that based on what you are saying.

If they aren’t biting, the concrete is shit. Using epoxy is just going to bond the anchors to the same shit.

It’s a dumb way to die.
 
Here's specs on concrete from the building plans - should all be 6" with 1/2" rebar - just poured a few years ago

Screen Shot 2023-06-30 at 9.44.26 AM.png


arse_sidewards said:
Sounds like a good plan to me. I'd be a little worried about the sleeve still not grabbing and the epoxy being the only thing holding anything in the hole though. But not worried enough to not do it. :laughing:

Also, vac sucks for getting dust out. Use a blow gun and shop air.
Click to expand...

Isn't that what epoxy is for? At that point, the sleeve wouldn't be utilized at all, epoxy would be filling the void under and around the anchor and locking it in place. I think. Never used the stuff before, part of why I'm asking here


arse_sidewards said:
Re-reading it....

Since half the anchors don't meet the depth requirement you should probably just pull the lift off and use different anchors.

Maybe step up in size to whatever redhead or tapcon fits the hole you drilled.
Click to expand...
M92PV4U said:
Maybe try something like this.
factorydirectsupplyonline.com

Simpson EZAC37434 3/8" x 4-3/4" Easy-Set Pin Drive Expansion Anchor

The EZAC easy-set anchor is a pin-drive expansion anchor for medium- and heavy-duty fastening applications into concrete. The EZAC anchor provides holding power in concrete base materials including both concrete masonry unit (CMU) and brick. The anchor includes an integrated nut and washer for...
factorydirectsupplyonline.com factorydirectsupplyonline.com
Click to expand...

I did slidehammer one of the anchors out - had a guy slidehammering for about an hour to get it. Was hoping to avoid hours of slide hammering if possible. Also, once the anchor came out, it was without the locking collar, which was still down in the hole


Muckin_Slusher said:
I'm sure more than a few people will call me a pussy, or tell me to fuck off to garage journal, but it sounds like your concrete is shit, or at least less than ideal.

It would be in the back of my mind for the rest of my life wondering when that thing's gonna fall over, even though lots of hoists have been installed on questionable concrete and most didn't fall over. I'm not an expert on anything, so I tend to be conservative and overbuild so it looks right.

I had to say it.
Click to expand...


That was my concern - at least in this particular spot of the concrete. Hopefully I'm not making it sound worse than it is - I actually think I'm overthinking it. I'd think it's highly unlikely that the whole lift would topple over and dump a vehicle on the ground, unless doing things really wrong. More likely that it might lead to cracking the slab if the anchors aren't deep enough - something along those lines. Would be cool to do it as close to 'correct' as possible, then never have to think about it again:homer:


Here's a more detailed look at things. First two pics are of the 'good' baseplate. Checkmark on top of the anchor means it's at least 3-1/4" in the slab. X means it's not, and written next to each anchor is how much is actually in the slab. So two anchors up to spec, three that are out of spec - but only by 1/4". I'd say that's probably good enough and not really worried about that side at all

IMG_9554.jpeg

IMG_9555.jpeg



Next two pics are the problem side. Three anchors are up to spec on this side, including the one in the extension that I added (second pic below). Three out of spec - one is only shy by 1/4" so probably fine. The other two are the ones I was hoping to use epoxy or something (although the one that currently has no anchor in it probably doesn't matter after adding the extension plate:

IMG_9552.jpeg

IMG_9553.jpeg


When I added the extension plate, I drilled just shy of 6" deep and put a 7" anchor in, but the collar didn't grab like the others. Torqued it, cut off the excess, it's 3 1/2" in the slab which is good enough, but should have been more. I could add another extension plate to the other side, but if the anchor doesn't grab again it's not helping all that much
 
I'll add that we have another lift in the next bay over, and concrete was fine over there with no problems during the install

Here's the best pic I can get down the hole that is missing an anchor. That was the only hole that ran into rebar. Instead of hitting it dead on, just hit the side of it, and I believe the softer material down there allowed the bit to push off to the side of the rebar instead of drilling through it. That was the worst one, hence the extension plate I welded in

IMG_9610.jpeg
 
desertPOS said:
IMG_9552.jpeg

IMG_9553.jpeg
Click to expand...

My lift is 2nd-hand and obsolete, so I reviewed a number of different lift mfr's instructions.

The big red flag I see is the cracking you have by the 'problem' column (also one by the good column.) That's a no-no from what I read - with some citing minimum distance from a crack or slab edge.

I also supposedly have a 6" slab, which I was warned could be +/-1" just because of grading irregularities. I went with 7" anchors and put them through the slab. Some of them pulled up quite a bit because the concrete blew out partly from drilling.
 
Aw jeez, don't use me as a reference. I'm just a highly regarded artist trying to find his way in the world.

Edit: since my floor was about 3" thick I had to cut and pour a new section for the lift. Figured since I had to do that I might as well make it big. Minimal additional cost over doing a 6" pour or whatever.

I'm using wej-it Epoxy anchors, in the 3/4" flavor. Overkill, but I like overkill.
 
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u2slow said:
The big red flag I see is the cracking you have by the 'problem' column (also one by the good column.) That's a no-no from what I read - with some citing minimum distance from a crack or slab edge.
Click to expand...
this

my hoist is one of them flat driveover ones and it's on about 2" of concrete that's really broken up

a two-post like that? don't fuck around with shitty concrete man, bust that trash out and redo it with proper rebar and such
 
desertPOS said:
Isn't that what epoxy is for? At that point, the sleeve wouldn't be utilized at all, epoxy would be filling the void under and around the anchor and locking it in place. I think. Never used the stuff before, part of why I'm asking here
Click to expand...

An epoxy anchor is designed to glue itself into a hole in solid material. The main concern would be how large of an area the void/"soft" area actually is?

I'd be inclined to recommend cutting the area out and replacing it similar to what GLTHFJ60 did. If you're really intent on using the slab as-is, I'd at least be drilling some smaller holes around the area to try to determine how large of an area is compromised.
 
How are you setting the anchors? I find if you start with a ratchet or wrench, the little sliding collars lock in sooner and easier, where as impacting the studs pull up a lot farther
 
The only anchors under tension are the outer three of each post. If those are suspect then fix/epoxy them all. Even if the concrete is questionable deeper down the epoxy anchor should do well where as the mechanical one won't.

Check the torque as the lift is used to see if they are holding properly.

2-post-lift-failure-jpg.jpg

see, no one was hurt
 
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rattle_snake said:
The only anchors under tension are the outer three of each post. If those are suspect then fix/epoxy them all. Even if the concrete is questionable deeper down the epoxy anchor should do well where as the mechanical one won't.

Check the torque as the lift is used to see if they are holding properly.

2-post-lift-failure-jpg.jpg

see, no one was hurt
Click to expand...

Except for the guy under the front left corner you can't see, lol.

I hope they wore their brown pants that day.
 
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