Pervious concrete contains a network of holes or voids, to allow air or water to move through the concrete. This allows water to drain naturally through it, and can both remove the normal surface water drainage infrastructure, and allow replenishment of groundwater when conventional concrete does not.
It is formed by leaving out some or the entire fine aggregate (fines), the remaining large aggregate then is bound by a relatively small amount of Portland cement.
When set, typically between 15% and 25% of the concrete volumes are voids, allowing water to drain.
The majority of pervious concrete pavements function well with little or no maintenance. Maintenance of pervious concrete pavement consists primarily of prevention of clogging of the void structure.
In preparing the site prior to construction, drainage of surrounding landscaping should be designed to prevent flow of materials onto pavement surfaces. Soil, rock, leaves, and other debris may infiltrate the voids and hinder the flow of water, decreasing the utility of the pervious concrete pavement.