During World War II, the United States military built an entire fleet of cargo ships out of reinforced concrete because traditional steel was in extremely short supply.

A closer look

During World War II, the United States military built an entire fleet of cargo ships out of reinforced concrete because traditional steel was in extremely short supply. Twenty-four floating paradoxes were constructed to transport sugar and vital commodities across the ocean. You might assume that building a ship out of sidewalk material is a terrible idea destined for the ocean floor, but these behemoths floated just fine thanks to basic physics. The sailors who operated them lovingly referred to them as floating tombstones, exactly the kind of dark humor you develop when your government hands you a giant rock and tells you to sail across a submarine-infested sea. While they were incredibly strong, they were also insanely heavy and burned through fuel at a rate that would make a modern billionaire blush. Most were eventually sunk on purpose to create breakwaters, finally returning the concrete to its natural resting place at the bottom of the ocean where it clearly belonged the entire time