IFC walls poured with river rock concrete.

[J.P.]

I am working on a project with ifc walls consisting fox blocks poured full of crappy concrete with river rock in it.http://www.foxblocks.com/products/fox-blocks/

Seems like a simple task to cut the foam away and shoot on a box with a ram set........
The cutting of the foam is simple and quick, its the attaching the box that is not working out.

The concrete blows out when the fastener goes in hits a rock and bends.
I tied 3/4 nails with washers. 1/2 nails with out. Red shot and green shot on various power settings.

2 boxes is secured properly, 15 are ruined. I need to fasten 26 boxes.

I tried the usual tapcon and masonry bit but the river rock in the concrete is too hard for the bits and destroys them. I went thought 5 drill bits and got very few holes drilled.
Maybe I need one of those medium sized hammer drills?

I did use some of the masons 2 part epoxy to attach one box to the wall. It seemed secure, I didn't try to pry it off with a crowbar or anything but I did tug on it with a pair of needle nose and try to wiggle it, felt solid.

Has anybody used epoxy to fasten boxes? Is it an acceptable method.

 

[mgookin]

The only thing I can find about aggregate in the concrete appears on this document:
http://www.foxblocks.com/media/8380/Fox-Blocks-Technical-Perfomance-Code-and-Testing-Data.pdf
Last entry in top section. But that's just "reccommended".

Personally I think their drawings are junk. Most things just say "per code" which is not allowed in construction drawings in Florida. That's like saying "I want to build a new 50 story hospital; Electric per code". Around here you have to provide specifics. I'm surprised ETL let them get away with that. I can see letting them get away with a statement "local engineering required - see local engineering" but then nobody would buy their product knowing they have to hire a local structural engineer on every project.

Not sure what to tell you on this.

 

[don_resqcapt19]

...
Has anybody used epoxy to fasten boxes? Is it an acceptable method.

I don't see why it would not be an acceptable method of securing and supporting the box. The code does not specify the method to be used. It sounds like the foam could support the box while the epoxy cures. Not sure about holding it back tight against the concrete.

 

[iwire]

I have secured parking lot poles with epoxy, I am sure a box can be held fast.

As far as code I agree with Don above me.

Here are some products that could work.

http://www.stickyquestions.co.za/stick-metal-to-cement-concrete-brick

 

[Cow]

We secured a large j-box, maybe 18x18, to a tile wall we were afraid of damaging with that 2 part epoxy that comes in a caulk tube. I wouldn't have a problem using it for device boxes in your situation, I bet you'd bend the box up trying to pry it off the wall after it cured.

 

[J.P.]

Thanks. That Gripfill looks like the ticket.

 

[kwired]

I'd bet general purpose construction adhesive would do pretty well in most cases, any epoxy type adhesive is likely even better.