Concrete that absorbs a whopping 600 litres of water per square meter per minute! You have to see it to believe it. Luckily Tarmac, the company that has invented this permeable concrete system called Topmix Permeable, has made a video.
Through the voids in the concrete, the water can flow to drainage systems where it can enter the groundwater. It even works in freezing temperatures:
A permeable design encompasses not just a structural design but also a hydraulic one. This design would be based on many factors such as the design storm event ground permeability and total area to be drained from. This would then normally determine the required thickness of the attenuation layer. (This is basically a storage layer made up of an aggregate with 30-40% voids). It is in this layer that the water would sit, not within the structure of the permeable surface layer so if the water was to freeze it would not have any detrimental effect on this.
Roads made of this material would be much safer than regular asphalt—no puddles or flash flooding. In the video, you can see 4000 litres of water disappear in 60 seconds!
