I am trying to anchor a tool rack to a concrete foundation wall. When I drill into the concrete using a hammer drill and masonry bit, the stones in the surrounding area come loose and I end up with a hole much larger than the drill and anchor size. As a result, the anchors have nothing to grab onto to hold them in place. Does anyone have any ideas that might help? Here is a picture of how the holes look after drilling: https://www.dropbox.com/s/96dd0zkyierbq13/Concrete.jpg?dl=0
tintop,
Apr 29, 4:48pm
Whoo! If the wall is that bad - I would have concerns anchoring anything to it. Someone forget to include a wee bit of cement in the mix ?
I guess that drilling as deep as you can, filling up the void with a slightly damp mortar mix rammed in with a suitable rammer ( say a length of broom handle) Keep as moist as you can for a week, come back and redrill the hole.
And dont put anything in/on/under the toolbox :)
Are you able to drill right through the wall? Get access to the other side ?
skipper42,
Apr 29, 4:58pm
Epoxy could be another option. I could bind the loose concrete particles together.
BUT, I suspect you have a problem with the concrete itself. sounds very unstable. Might be better to come up with a "Plan B"
tintop,
Apr 29, 5:17pm
Yes - Plan B Drill all the way through, bring up timber against both faces of the wall and bolt right through.
cat-nine,
Apr 29, 5:33pm
Thanks for the advice. :) I think I will go with drilling through and using timber as that sounds like it will be a lot more stable. Do I need to do anything to stop moisture/rain from penetrating through the bolt holes? I was wondering about epoxy. Since the cured epoxy is supposed to be stronger than the concrete itself, can it be drilled later on and support an anchor or would it just end up pulling away from the concrete?
tintop,
Apr 29, 6:07pm
From the look of the concrete in the picture, and what you have said about drilling it - I really would be reluctant to hang anything from it directly.
Something like this would do:
Prop up a length of timber on the outside. 100 x 50, treated to at least H3.2.
Drill the hole in the concrete all the way through.
Drill a 10mm hole in the timber.
Knock in a 10mm galvanised coach bolt, length = the thickness of the concrete + 125 mm.
Fill the void around the bolt with dry packed mortar ( premixed plasterers or block layers mortar is ok, but use only enough water to make it damp.) Leave slightly proud on the inside.
Use a shortish length ( make sure it is long enough to span the hole) of 100 x 50, with a hole of about 15 mm, place this over the free end of the bolt followed by a 10mm x 50mm square washer and fasten the nut up firmly.
Carefully remove temp timber from the inside after a couple of days. Scrape back the excess mortar.
Wait another few days - and there you go!
Repeat as needed. :)
cat-nine,
Apr 29, 6:30pm
Thank you tintop! Much appreciated. :)
johotech,
Apr 29, 8:44pm
Well you've got some good answers, but I'm wondering if it might be a bit over the top.
You say you want to attach a tool rack, do you mean something to hang a fork & shovel and a few other thing on, or something much heavier?
I can't see the holes you have drilled in your photo. But it is obviously river gravel concrete. Quite common in the old days.
What you will find when you drill it is that some stones will break off around the outside, but once you are around 20mm in, it will become more solid, BUT, you need to use a rotary hammer drill, not just an ordinary drill with a hammer setting. The way they drill is totally different, and that is possibly why you have pieces breaking off.
So depending on what exactly you are trying to attach, usually most of the force on an anchor is downward, rather than outward (trying to pull the anchor out).
I would bet that you can easily get a 10mm or 12mm anchor to hold successfully with around 75-100mm into the wall, using a rotary hammer drill.
Yes - that could be tried, if it does not work - at least you will still have plan B to fall back on.
exfish,
Apr 29, 10:30pm
If you are going to drill right through be just as easy to glue some threaded rod in with some chemset, will never pull out.
johotech,
Apr 29, 11:42pm
Yes chemical anchors work great. But you have to be able to drill a decent hole first!
tintop,
Apr 30, 12:26am
In sound concrete - yes, in the concrete that the op has got - perhaps not.
tintop,
Jan 20, 4:48pm
And the concrete has to be sound enough to anchor to.
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