First thing I thought when I saw the sidewalk was that it looked like a cake aswell
I assume it was sculpted? It looks like you've just gone at it randomly in zbrush to give it some texture, which to be honest, I really don't think it needs.
At most you could perhaps model a nice high poly mesh, but for all the surface detail, I think you could knock out a simple height map in photoshop, and turn it into a normal map.