Engineers to the rescue! Concrete Bolts gone wrong - help

[Aerides]

So....

Let's say something was bolted into place in concrete and now needs to be moved. And let's say it was bolted in with the type of anchor that expands below the surface and only goes in, not out. 1/2", 4" anchors, heavy duty, pic below

But the unit that's anchored needs to be moved, and the anchor needs to disappear, below the surface...which is nice tile, on top of the concrete, that you'd really rather not destroy in the process. And even if you do, the bolt has to get super flush with the underlying concrete so you can replace the tile paver.

What is the best way to proceed?

Ultimately, I'd like to remove the unit, knock the anchors into the concrete below the surface of the tile, flush or below with the concrete, and then replace the tiles. But I realize that might require very specific expertise/tools.

So as a second option if I can safely drive the anchor in to be just-below-flush with the tile without busting the tile, I can Traverfill the surface and be ok with that (outdoors).

Here's the kind of bolt:

As a visual, current situation is not unlike this, but instead of that red tile thing think a much nicer paver:

 

[Time2]

I don't think you can drive it any further into the concrete, I suspect it is already at the bottom of the hole that was drilled for it.
I don't know how hard the stud material is, but, I would try cutting it flush, then center punch it to get a dimple it the center, drill a small hole down 3/4 ", then use a larger bit and drill again and then a 3rd drill that removes the rest of the stud material. Fill as needed.


Cut it flush with a hand grinder.

 

[finnski1]

So....



But the unit that's anchored needs to be moved, and the anchor needs to disappear, below the surface...which is nice tile, on top of the concrete, that you'd really rather not destroy in the process. And even if you do, the bolt has to get super flush with the underlying concrete so you can replace the tile paver.

What is the best way to proceed?

Ultimately, I'd like to remove the unit, knock the anchors into the concrete below the surface of the tile, flush or below with the concrete, and then replace the tiles. But I realize that might require very specific expertise/tools.


Here's the kind of bolt:

As a visual, current situation is not unlike this, but instead of that red tile thing think a much nicer paver:

Well if you are going to replace the tile why not just remove the nuts, remove the tile and then cut the bolts flush to the concrete with a sawzall and metal cutting blade. Then just replace the tile? No special tools other than a sawzall(reciprocating) saw.

 

[street]

If it were me, I would try to drive one down but don't get cowboy with it. If you can drive it down some then up, and use a bolt cutter and cut off. This would prevent the existing tile from any damage.
The bolt then would drop down below the concrete surface and fill in with filler and smooth flush. I would try this processes first and see how one goes.

 

[Jerry1]

I would cut the bolt off at the surface and then drive the anchor down. Then I’d get some epoxy and fill the hole, matching the tile as best I could.

You may not be able to drive the anchor down because the hole that was drilled in the concrete may have been just enough to seat the anchor. So it’s probably already bottomed out. In that case, you may have to grind down the top of the bolt, just enough to give the epoxy enough to room to be thick enough to be a good seal. A cone shaped grinding wheel would work.

 

[Jerry1]

On second thought, I wonder what would happen if you got hold of that with a pipe wrench and twisted it. If twisting it breaks it loose, you may be able to wiggle them out. You may also get lucky and it could break off below the surface.

 

[Aerides]

The concrete is way below the depth of the bolt. It's a footer, at least 3 feet deep. The anchor is in about 3" of it, after the tile/surface. not sure how far the original holes were drilled but not going to count on there being more than an inch of pre-drilled space underneath.

Is there a commercial bolt cutter that can cut a half inch bolt? And what kind of a grinder would work? (I'm a novice beyond wood tools...)

For all the tools feel free to link or provide names!

 

[Mark1]

Sounds like you are planning on replacing the tile, which is on top of a concrete surface, and the bolts are not coming back in the future. I would probably try to cut/grind off the bolts prior to and/or after the tile has been removed and then re-tile over, assuming that is the plan. Some of the other wreck out options might actually do some damage to the underlying concrete surface.

The one thing that might bother me about leaving the bolt in place would be that as they corrode, the corrosion product needs even more space and might start to push up on the new tile. Therefore, after cutting them off I might even be inclined to drill some of the bolting out to create a cavity area for future corrosion product. ??

 

[latexman]

Is there a commercial bolt cutter that can cut a half inch bolt? And what kind of a grinder would work? (I'm a novice beyond wood tools...)

Is there only one plate? If so, for a bolt cutter rated up to 1/2" bolts, that'll probably cost about $300. If it were me, I'd disassemble it as far as I could, and then subcontract a mechanic/handyman (bolt cutter/grinder) or welder (acetylene torch outfit). It should be cheaper, unless there's several plates to do.

 

[Ready-4-ER-at-14]

The question that came to my mind was if something is that secure I would wonder if it was a structural support and if removing it would result in problems like sagging or collapse. And if so would you have appropriate supports in place before removing the column/support to make it safe to remove. ... And if it was something like just a table in a commercial setting that was anchored disregard this post. : )

 

[ERD50]

So...

Ultimately, I'd like to remove the unit, knock the anchors into the concrete below the surface of the tile, flush or below with the concrete, and then replace the tiles. But I realize that might require very specific expertise/tools. ...

The key is here that you will replace the tile. That makes this much easier, and I will follow Mark1's lead, but I feel stronger about this - do this 100% correctly - it won't be much more effort - do it right the first time. A second repair will be much more work.

Cut the bolts flush, then drill them out to get most/all of the metal out. Fill the hole with the mortar when you replace the tile to avoid the corrosion and possible expansion/cracking issues in the future (when something rusts, it expands and can crack the concrete - this is likely a contributing factor to the Florida condo building collapse).

Since you are going to replace the tile, I'd leave the old tile in place while I cut/grind/drill the bolts out. That old tile will provide some protection to the edges of the adjacent tiles while you do that work. Remove the old tile last.

-ERD50

 

[nash031]

So I've installed about 40 of those concrete anchors in our gym recently. Normally, I don't bottom them out in the hole that's drilled. In fact, the instructions for those anchors encourage leaving a small gap below the anchor, so you might drill a 4" deep hole for a 3.5" deep anchor, for example.

You could try to hammer them in a bit more, but ultimately you're going to have to do some cutting/grinding. Unless the anchors are improperly installed, I seriously doubt you're getting it out of the ground any other way.

As to what tools would work, I've cut one of those with a hand hack saw in less than five minutes, so any grinder/sawzall with a metal cutting blade would work.

 

[finnski1]

So....





As a visual, current situation is not unlike this, but instead of that red tile thing think a much nicer paver:

Do you have a picture of the actual situation?

 

[Jerry1]

If you don’t have the tools, I’d find a friend or hire a handy person to cut the bolt off. Basically, I grinder with a cutting blade will work, but so will other tools like a dremel or as was mentioned, even a hack saw.

 

[OldShooter]

A grinder with a cutoff wheel (even a Dremel used with patience) will cut the bolt no problem but getting close to flush without damaging the tile will be close to impossible. Power tools let us make mistakes very fast.

I would try @Jerry1's idea in post #6 and hope to get lucky.

Absent good luck, I would cut the bolt as square as I could and as near to the tile as I dared. Then I would try whacking it down as has been suggested.

Again absent good luck, I would center-punch the bolt and try to drill it out using progressively larger drill bits. Use good drill bits as this is probably Grade 5 or similarly hardened steel, then resign yourself to ruining the larger bits as the hole will inevitably be a little off center and the drill will be hitting some tile and concrete.

No fun.

 

[Tetto]

I don't think you can drive it any further into the concrete, I suspect it is already at the bottom of the hole that was drilled for it.
I don't know how hard the stud material is, but, I would try cutting it flush, then center punch it to get a dimple it the center, drill a small hole down 3/4 ", then use a larger bit and drill again and then a 3rd drill that removes the rest of the stud material. Fill as needed.


Cut it flush with a hand grinder.

This is exactly what i would do.

 

[Time2]

This is exactly what i would do.

You're a wise man, Tetto.



Angle grinder less than $20 at Harbor Freight.
https://www.harborfreight.com/power-tools/grinders-sanders/angle-grinders.html

 

[Aerides]

Do you have a picture of the actual situation?

I'll try to add later.

I have a bit more info: There should be a layer of paver sand between the bottom of the pavers, and the top of the concrete. That would make lifting/replacing the pavers the best approach, and then removing the need to perfecting shave the old bolt. Just grind it off a bit below the surface and never see them again, replace with new paver...

Basically, I had pergola assembled and installed by a crew that (in hindsight...) lacked the expertise to do so. It's not drilled in properly, they didn't center it... it's a bit of a nightmare and I could cry and scream but I just want to figure out how to fix it, and not make it worse doing so...

 

[finnski1]

I'll try to add later.

I have a bit more info: There should be a layer of paver sand between the bottom of the pavers, and the top of the concrete. That would make lifting/replacing the pavers the best approach, and then removing the need to perfecting shave the old bolt. Just grind it off a bit below the surface and never see them again, replace with new paver...

Basically, I had pergola assembled and installed by a crew that (in hindsight...) lacked the expertise to do so. It's not drilled in properly, they didn't center it... it's a bit of a nightmare and I could cry and scream but I just want to figure out how to fix it, and not make it worse doing so...

That is why I suggested what to me was the easiest and will end up being the best looking result.
1) remove nuts
2) lift/pry up paver
3) cut bolt flush to concrete with reciprocating saw and a metal cutting blade. Very easy
4) install new paver.
No drilling, no pounding, no grinding, no filling, no twisting the old bolts etc.
This inexpensive saw would be fine.

https://www.homedepot.com/p/RYOBI-12-Amp-Corded-Reciprocating-Saw-RJ186V/204601267
and a blade like this.

https://www.homedepot.com/p/DIABLO-...ng-Reciprocating-Saw-Blade-DS0920BF/203464738
or a blade kit like this, just pick a metal blade

https://www.homedepot.com/p/Milwauk...g-Saw-Blade-Set-10-Piece-49-22-1110/303135934

 

[JoshTrent]

To me it's a little unclear how the pergola is attached to the concrete, and the size/weight of the pergola. It seems that the stud is penetrating both the Paver and the Concrete? If that is indeed the case, it's no wonder that you question the expertise of the installers.

To complete a removal of the structure in the correct manner, it is going to take some effort. I am of the mindset of doing things "right", so my advice is..

Remove the structure
Remove the offending pavers (with drilled holes)
Grind bolt studs flush with concrete - an angle grinder will work best**
Replace pavers include paver/polymeric sand to match original install

**there is no sense in wasting energy pounding on studs. As long as the are ground below the depth of your bedding sand, they won't pose any problem.

At this point, you would have a completely flat/bare paver patio.

For the new installation location, I would suggest an installment technique similar to what is in this video:

All of the fastening is done below the pavers, so you will need to remove pavers at the new locations. This will secure your structure to the concrete footings, without the pavers & sand involved in the joint. You can then either trim pavers to fit around the new posts (good recycle of those that were previously drilled) & use some trim around the base of the posts to cover the attachment OR put down decorative rock around each post.

Specialty Tools Required: Angle Grinder & Hammer Drill - Assuming you are in the US, you would be able to rent this from your local Home Depot or Lowes. (wear safety glasses!)

If the new location of the pergola puts the posts on soil, then you will likely need to pour new footers. Pouring footers may sound intimidating, but it's a straightforward task. IF you go this route, resist the urge to cast bolts in your footer pour. I think you will have better success drilling your hardware.

I would suggest a visit to a local backyard store or rock/stone company - they would be a good source for the hardware needed. They'd also be able to point you in the right direction for a reputable contractor (just in case).

Begin with the end in mind!

EDIT TO ADD:
- re-reading your OP leads me to believe that the legs of the pergola are metal, with a flange welded to the base. If that's the case, when placing the pergola in the new position, attach it directly to the footer with wedge anchors, no additional hardware needed. You can then finish the space around the base of the leg in a manner you see fit.

 

[Aerides]

Here's one of the posts (there are 4) showing how it's currently anchored.

In the meantime, I went over to a local custom pergola company. (why didn't you go to them originally Aeri? Because I wanted to save $8000....their customs start at 10k...)
I explained my situation and they propose to do this thing right. Lift and move it, but anchor it to the footers, not on top of existing pavers, then cut the pavers around it, around the base to fit (no exposed screws or plate. They will then remove the old screws and replace the tiles with the holes. It will sit about 2" lower but that is not a problem at all.

They propose basically the proper professional way to install this sort of thing. It will probably be a half day job for two installers... I've sent over pics and now I'm awaiting the quote but I think at this point it might be the best way forward and the best way out of a bad situation. I got in this mess by trying to save money after BTD'ing on the pool...

 

[JoshTrent]

Yes.. that is a poor installation.

I agree with the advice given from the company you reached out to. So long as one has a way to move the pergola around, I don't see any reason why any DIY'er couldn't do this work themselves.

 

[NgineER]

Here's one of the posts (there are 4) showing how it's currently anchored.

That was poor execution! If you could move it by yourself it wouldn't be hard to do it right... But it might be worth $1k to have someone else do it while you are enjoying a drink by the pool...

If DIYing it, I would remove the paver and then cut the bolts off with a simple angle grinder. The cutting would be a quick affair.

 

[ShokWaveRider]

I don't think you can drive it any further into the concrete, I suspect it is already at the bottom of the hole that was drilled for it.
I don't know how hard the stud material is, but, I would try cutting it flush, then center punch it to get a dimple it the center, drill a small hole down 3/4 ", then use a larger bit and drill again and then a 3rd drill that removes the rest of the stud material. Fill as needed.


Cut it flush with a hand grinder.

I second this approach.

If you are going to replace the tile anyway, an alternative option would be to remove the tile, then drill around the anchor with a good concrete drill, then remove the anchor and fill in the concrete.

Either I think old work.