Cinders?

[Sumpter250]

Actually, as I remember, we had cinders in our driveway......probably from the same furnace, and they were a light gray/tan color. Heavy equipment would most likely have concrete slabs to sit on, if they needed that kind of stability ( especially the more precise things like wheel lathes, and driver quartering machines, that had to maintain very fine tolerances). Cinders aren't quite as hard as concrete......close, but not quite, general flooring yes, heavy machine bases?....probably not.