Permeable paving stones (also known as drainstones) are when the material of the paving stone has a certain water permeability. The paving stones (or paving slabs) are made of so-called porous concrete, a concrete with an open-pored structure that causes water and air permeability. Surface water can seep directly through the stone. In order to achieve sufficient and, above all, permanent infiltration capacity, the joints are also designed to be water-permeable.
Permeable paving with filter effect: Systems with water-permeable paving stones are now on the market, which also act as filters for fine dust, heavy metals and mineral oils. They are generally approved by the building authorities as part of a permeable surface pavement, even in highly frequented areas of road traffic (more than 300 cars per day). The systems also include special joint and bedding materials. In order to ensure the filter function over a longer period of time, special cleaning is necessary after about 10 years, during which the joint material is also replaced. The pavement is rinsed through and the pollutants introduced into the material are sucked out.
Source: bauwion
