With polished concrete floor, if i am standing and looking near me, it doesn’t look so polished, but if a look further away, where the angle between my eyesight and the viewpoint is smaller, it looks very reflectice, as you can see in the reference photo.
I would say the opposite - reduce the roughness on the glossy node to close to zero, or even zero/sharp if speed is required. The original looks to have pretty sharp reflections.
My approach would be:
Textured diffuse and bright glossy (0.6-0.8’ish). Mix or additive shader, go mix with fresnel unless you’re sure. Looking at the picture, it appears the amount of reflection is varied, so maybe plug in some noise here as well (roughness appear fairly uniform).
Diffuse to also have bumpmap plugged into its normal input. I wouldn’t bother with glossiness on the concrete layer, although I suspect it would have a tiny amount of it. It’s like increasing the rendertimes for no good visual reason.
Same bump normal plugged into glossy, but (very important) mix it with a fair amount of umodified normal so you can control it’s bumpiness. This coat layer will smooth out the underlying bumps, but may still inherit a tiny fraction of it.
Maybe your reflections are not far from you target. I think your scene is dark. Try to set more light in the foreground. Increase lightly the IOR for the glossiness (1.3 or 1.4)
If you want to imitate the reflections of your reference, put a picture on the wall. In your reference the pictures are clear and the wall is dark. Do something similar and compare it.
I’m not sure about the bumping. That kind of floor uses to be too flat. If you want try to set a bump texture in your diffuse node and not in your glossy node. See the effect.
Epoxy coating is used to seal the concrete floor, which is good for working areas or otherwise dirty environments. There are other benefits too so it could be used as a cosmetic finish, but I wouldn’t say “usually” http://en.wikipedia.org/wiki/Polished_concrete
