How do porous pavements work?
Porous pavements, such as pervious concrete and porous asphalt, have functionality and workability similar to that of regular concrete and asphalt. However, the porous mix lacks fine particles found in regular mixes. This creates a significant amount of void space which allows water to flow relatively unobstructed through the pavement. Once through the pavement, the water is flows into the infiltration bed beneath, which is filled with rock, producing a 40% void space for storage of the runoff until it is infiltrated into the soil.