Grinding bolts below concrete surface

[Hagatronics]

I'm about to expoy a factory floor and there are quite a few old bolts/dynabolts cut flush with the floor. I want to grind them at least 5mm below the surface so I can fill with epoxy putty and finish flat before the surface is epoxy coated.

Do I use a masonry grinding disk or a steel grinding disk ?

 

[Retroman]

I think either would work, I would try the steel first and go from there.

 

[Muckin_Slusher]

I'm assuming you've already tried smashing them deeper (or are they epoxied in the holes?)

Acetylene torch might be a lot easier, but the concrete may spall a bit (which could be beneficial as you'd have a bigger/rougher hole to fill.

 

[ilovevocs]

I think I would try to drill as much as possible before grinding. Perhaps you could drill all of it out or enough that you could collapse what’s left with a punch.

Did you hit them with a punch and a hammer to try to embed them deep enough?


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[GaryM909]

Maybe try a cone stone with an angle grinder.

 

[Farrier]

I'd grind lower and use hydraulic cement to fill and smooth

 

[greenghost]

How about an air hammer? I trim concrete with one made for muffler work. Have driven anchor bolts up to 3/4" into the concrete. Five pound air hammer for any thing 1 1/2" too 3". Fifty pounder for anything over 3". Have Fun!

 

[619DioFan]

carbide burr in a die grinder would allow you to take them down below floor level without causing much damage to the concrete.

 

[kerrynzl]

Cut the bolt heads off , then drill a shallow pilot hole.

Then use a countersink drill bit to take it below the surface.

 

[racingtadpole]

Put a steel disc on and get on with the job. Lots of really great suggestions above for turning a straightforward job into an epic. If you really want to get **** about it get a Kango and chip the concrete away to remove the entire fastener.

 

[tncatadjuster]

I bid a decommission of a warehouse with 12,000 bolts to grind smooth. We ground smooth with cut off blade then struck with hammer to sink below surface, epoxy patch.
Turned out out to be a great job.

 

[BFBOB]

did you slip a decimal point there??
12 THOUSAND of any task would give me heart palpitations!!

 

[Hagatronics]

I'm starting the job in 2 days. Will report back on how. I'll be taking a small sledge hammer and a punch!

 

[tncatadjuster]

did you slip a decimal point there??
12 THOUSAND of any task would give me heart palpitations!!

It was a 650,000 square foot automated fulfillment center. Everything was bolted to the floor. I was not sure how to bid it, but it worked out great. Four guys two weeks.

 

[sberry]

I was going to ask about the bid. That is pretty good time.

 

[BFBOB]

Let's see - standard work week, that's 320 man-hours, or 19,200 minutes. Less than two minutes per bolt. That's flying!!

 

[joe49]

If pro installed the holes will be drilled deep enough to lose the hilti bolts with a hammer.

 

[tncatadjuster]

Let's see - standard work week, that's 320 man-hours, or 19,200 minutes. Less than two minutes per bolt. That's flying!!

$2

 

[Hagatronics]

About 30 dynabolts were easy to punch down.

About 30 were old fashioned lockson anchors (female threaded anchor) and wouldn't budge. 7" grinder with a steel grinding disk worked ok.

 

[Firstram]

If pro installed the holes will be drilled deep enough to lose the hilti bolts with a hammer.

Joe gets it!

That is the most difficult thing to teach the new kids. You can show them why it matters every morning and have to show them again after you turn back for 5 min.

 

[sberry]

Ain't only kids.