I've really enjoyed the discussion on the cement plants. I just want to confirm that the cement plants being discussed are the ones that produce the actual cement raw material that is then later mixed with sand/etc to make concrete.
My interest lies in the small town cement dealers who would receive that product produced at the cement plants via the railroad and then mix the cement with sand/etc and then sell it to the local community like Petersen's Redi-mix would in Blue Rapids, KS. I will upload a picture of the plant circa 1950s-1960s in the photo section under the album named "Obermeyer photo album" in the photo section.
Petersen's had the Big Blue River and sand pits near by so they wouldn't need to bring sand in by rail, but they would require the cement.