It’s a bit like a large-scale magic trick. In the video above, a truck dumps gallon upon gallon of water onto the pavement, and it all seems to disappear the moment it hits the ground.
Behind the magic: Topmix Permeable, an absorbent concrete that's made by Tarmac and able to filter 880 gallons per minute through its pervious top layer. The water then goes to a drainage system where it re-enters the groundwater system.
The porous concrete could help to prevent flash floods by serving as a reservoir during heavy rain periods. It could also improve safety conditions simply by reducing puddles and overflow, plus it stays cooler than most asphalt in the sweltering months.
While the “thirsty” Topmix holds a lot of promise for many regions, it’s untenable in colder climates, where frozen water in winter months would expand and wreck the surface.