Tom - I always love seeing a layout with huge industrial structures on it! I lived in southeast Michigan the first 13 years of my life and developed a lifelong passion for steel mills and the lakeboats that served them. My dream was to model an industrial river scene like that of Buffalo, NY, which had both a steel mill but also lots of grain elevators lining the waterfront, like their "Elevator Alley":
https://en.wikipedia.org/wiki/Grain_elevator#/media/File:Elevator_Alley.jpg
...of course this was decades before I was mature enough to understand the impracticality of modeling a busy Lake port!
Had to settle for a steel mill only...
BTW - if you're still looking for ideas on
realistic-looking concrete-colored paint, I can show you what I used on a coaling tower:
Krylon Ultra-Flat Khaki in a rattle can. in normal lighting it looks a lot like aged concrete - and no acrylic "sheen" whatsoever.
View attachment 123020
(
The glare from the incandescent floodlamp makes it look more pale than it actually is...)