How do I remove a damaged screw from masonry?

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Old 03-07-19, 01:11 PM
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How do I remove a damaged screw from masonry?

I recently removed the screening on my lanai to accommodate an extension with pavers. Some of the screw tops broke off about an eighth-inch above the floor, with sharp edges. I've tried grabbing them with pliers, but I couldn't get them to budge. What's the best way to remove these screws from the concrete?

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Old 03-07-19, 02:07 PM
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Removing will be tough. One option would be to cut into the concrete with a diamond blade down and through the broken screw. Then remove the top piece and repair the concrete.
The part of the screw sticking up could be ground down to flush it that is ok. the flush surface might still rust.

To actually remove it I would use a concrete drill bit and drill 3 or 4 holes right next to it as close as possible. Then some chipping and twisting it might let go.

What does the resulting surface need to look like?

Bud
 
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Old 03-07-19, 02:26 PM
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Have you tried with vise grips?
 
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Old 03-07-19, 03:16 PM
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Thanks, marksr and Bud9051.

I haven't tried vice grips yet--not sure if there's enough exposed to get a grip, but I will try that.

Do you think I could drill through the screw with a bit that's smaller than the screw diameter and then remove enough of the screw to seal the top part of the hole with caulk or cement?

Art
 

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Old 03-07-19, 03:23 PM
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Drilling will be tough, hard to get a bit to stay on the remnant of that screw. I'd take a grinder and cut off what I could and then patch the concrete.
 
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Old 03-07-19, 04:00 PM
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What do you have for tools. A dremel is a handy tool to have around, use mine frequently for many little jobs. I have a diamond blade about 3/4" diameter that would handle both the concrete and the screw. The also make diamond blades for circular saws, grinders, and my roto zip.

It would be best to get the screw cut as far below the surface as possible to reduce the rust bleeding through, if it is a steel screw.

Bud
 
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Old 03-07-19, 04:40 PM
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Do you need to re-use those holes with new screws ?
If not..... just use a cold chisel to shear them off.
 
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Old 03-07-19, 04:49 PM
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I'd use an angle grinder and grind the protruding bolt down flush. If you need to re-mount something I'd drill a new hole.
 
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Old 03-07-19, 04:55 PM
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Two options- go big, or go small

1) Go Big-
Scrounge up a circular saw and a grinding wheel, grind off the entire the screw head flat to the concrete.

2) Go Small-
Scrounge up a dremel and a mini grinding wheel, cut the screw head off flush with the concrete.
 

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Old 03-08-19, 06:02 AM
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I do not like Tapcon for this reason. I've had them break when being installed and break while being removed. I much prefer expansion type anchors. When drilling the hole for them I go all the way through the slab if possible or double the length of the bolt. Then in the future if the anchor bolt is no longer needed you simply hammer it down into or through the slab leaving only a tiny hole at the surface to patch.
 
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Old 03-09-19, 11:16 AM
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Thanks, all, for the ideas. I don't have a Dremel tool. I think what I'll try next is to drill an eighth-inch hole in the concrete right next to the screw and see if I can dislodge it with a hammer and pull it out. I'll keep drilling holes around it until I loosen it and I can pull it up. I don't mind then filling the concrete hole that would be left.

Art
 
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Old 03-09-19, 10:18 PM
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After you drill a smaller hole in the center of the bolt, get an "Easy Out" in a diameter that fits the small hole you drilled. Shoot some penetrating oil around the broken bolt and wait a while. Tap the top of the broken bolt slightly with a hammer.

Then, insert the Easy Out, attach a Crescent wrench and turn slowly to pop the broken bolt out.
 
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