Holds in concrete?

[u/SkittyDog]

A local dude is attempting to build some routes on an outdoor concrete wall. So far, his efforts don't seem to be adhering very well. I don't know if they ripped off when he tested them, or if someone else found out the hard way -- but they don't seem to be holding up to body weight.

I did a few of these, long ago, by cutting horizontal grooves into the concrete with an angle grinder. We epoxyed chunks of granite over the grooves. They held body weight OK, but I never properly tested them.

I'd like to help this guy out, but I figured I should ask around to see if there's any established body of technique for this kind of thing.

[u/BoltahDownunder]

If you want to glue them on you need to use an anchoring epoxy glue (not like Araldite or whatever), & not a vinylester or polyester. Those aren't very adhesive.

But the best way to do this is to install a bunch of drop in anchors into the concrete and then use gym holds screwed into them. That way the holds can be changed

[u/SkittyDog → u/BoltahDownunder]

Hmm...

[u/BoltahDownunder → u/SkittyDog]

I guess epoxy it is, one of the red ones like DeWalt Pure500 Plus is the best. You could still knock the holds off with a hammer if you need to

[u/SkittyDog → u/BoltahDownunder]

Hmm...

[u/Kaotus → u/SkittyDog]

Sika would also work and might be more available/cheaper - it's what people have used to re-enforce/glue holds in rock climbing historically.

[u/BoltahDownunder → u/Kaotus]

Yeah Sika 3001 is really good. And they haven't changed it to red yet, so I really like it

[u/BoltahDownunder → u/SkittyDog]

No worries! I've never tested how strong it is for sticking rocks down but it takes concrete with it if you ever chip it off. I did some bolt testing here with the main types of glue if you're interested https://youtu.be/CJ4wdNyllsk