They are left over *hoppers* for creating concrete, asphalt, and a littany of other coarse sands and gravel mixtures for roads, foundaions, slab floors, ect..
Partial structures from the original plant left over because of the inabilty to move them elsewhere
![Image result for concrete plant processing](https://th.bing.com/th/id/OIP.Y19hDFO_AY7VOP9yLmMu0AHaEh?w=262&h=180&c=7&o=5&dpr=1.25&pid=1.7)
They are now manufacture from metal, as to relocate if necessary