Wow that's one great looking square'ish bag thingy, or whatever they're called hehe, but i mean perfect modeling.. and the nice looking studiosetup you placed it in.
The concrete wall has a very simple setup. I created the reflectance map from scratch then i used it for the bump (after a few tweaks in PS). This material uses two BSDF layers controled by a weightmap (again the reflectance tweaked) where i used a lambertian roughness for the 1st layer and arround 15 (i can't remember the exact value) for the 2nd one.
http://www.3dallusions.com
"Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."
Albert Einstein