The land surface in forests can absorb up to 80 to 90 percent of the rainwater, but in the land of cities covered with asphalt and concrete that is not water-executing, this percentage drops dramatically to only 10 percent, a problem that appears more clearly as the number of people migrating from Villages to Cities and the more paving in return. The way humans fix this imbalance was to build a coherent infrastructure system capable of draining the storm's rainwater, but it got worse after most drainage systems became outdated and unable to keep up with the increase of rainfall associated with climate change. When rainfall exceeds the capacity of the drainage system and infrastructure, dangerous floods are formed immediately, attacking everything.

The idea of paving with water capable materials is not new, urban architects and designers have begun to use these materials in paving pedestrian areas for up to a decade, and engineers have used porous concrete and put them under the basic paving layer as a drainage aid, but what is new in this material, created by a British company called Topmix Perable, is that it is the first executed material placed in places with high pressure and heavy body parts unlike in usual pedestrian areas.
The material used was tested in a parking lot, where the concrete absorbed 880 gallons, or about 4,000 liters of water, within a minute, as the water disappeared as soon as it reached the ground.
Traditional concrete is not water-accessable, and sand is an essential component of it, and it does not absorb more than 300 milliliters of water per hour, enough to deal with a large storm every 100 years, but this thirsty concrete depends on a type called "concrete without a pout", i.e. it is replaced by the small sand that exists, small pieces of relatively large crushed granite.
When rain falls on Topmix concrete, it is enforced by porous concrete, which has a base of gravel layer with large inter-distance spacing, and it filters pollutants in this process as well as mixed motor oil with water, to rain down and join the groundwater stock, or to be directed to other purposes such as crop irrigation or toilet cleaning water, depending on the ability down the soil to accommodate, you will not need to build tanks, while you have this smooth mechanism for drainage.
The company says that the new concrete will not only be useful in the discharge of floods, but it will be important in the hot weather as well, during periods of heavy rain with high heat, the water stored below evaporates generating a cooling effect reducing the temperature of the surface.
Areas that suffer from harsh cold will not be suitable for this concrete, as it is likely that concrete will be destroyed, because of the inter-distances between the particles that allow the freezing of water, which makes the surface above them break. The company warns against paving places with high vehicle density, saying that it is more suitable for parking places, short lanes or entrances more than highways.
Don't expect porous concrete to become the new material for paving your house street instead of asphalt so quickly, topmix is not yet available except in the UK, and it has limited options so far as mentioned above, in addition to being unable to provide flood protection to coastal cities against sea level rise, because the lower soil in these places is already saturated with water, so the rain will find nowhere to go. Experts said it will only be useful in protecting against floods and rivers. The question now is: will the Arab world, particularly the stricken and threatened countries, benefit from this concrete in the future or not?

Eng. Ghassan Fawaz Tabra
Ministry of Infrastructure Development