|Will be confiscated|
Concrete is an unused item in The Escapists, as evidence by it's item ID still in the game's files, but can not be found anywhere in-game. Concrete appears to be similar to Dirt, as it has the same texture, and possibly the same use. Originally, it might have been obtained by digging up the floor instead of just the grass.
It is only possible to obtain this item by hacking it into the game.