I need to install some hooks on my wall, which I plan to use to perform elastic band exercises. Hence, I need to install these very well so that they will handle the stress properly.
Situation is I have found an strange wall on the rental apartment I'm living. I was convinced it was a concrete wall because it feels sturdy when I hit it. Then I drilled a hole on it with too much ease. It's almost as if it is made of sand, and at some point (after 2 inches) the wall feels hollow while drilling.
My conclusion is that the wall thickness is 2 inches. At this thickness, I don't think the wall will be able to support the 3 sleeve bolts (5/16 x 2 1/2 inches) required to install this system.
I wonder if I have any alternative here, maybe using different screws? Glue? Any other method?
NOTE: Old building, perhaps 60's to 70's construction. Brick on the outside.