Permeable pavers or permeable interlocking concrete pavement (PICP) reduce pressure on already overused sewage systems and reduce pollution in the environment by providing a better way to handle rainwater. Instead of allowing water to merely run off the surface into local drains, often carrying pollutants with it, permeable pavers allow this water to seep between the pavers down to various layers of specifically constructed gravel and soil.
Depending on the kind of system you use, this water then goes back into the groundwater table or is captured and then slowly released back into the drainage system — thus reducing overflow during heavy rainfalls or snow melts.
Permeable pavers are not exactly permeable. In fact, rainwater or runoff does not filter through the pavers to the specially prepared gravel and soil beneath. Instead, when you lay out a system of permeable pavers, they have gaps between them that allow water to pass through to the various layers underneath.
Permeable pavers are made from fired clay brick or concrete. Crushed aggregate is then used to fill the joints between the pavers. This aggregate is composed of crushed quartz, granite or marble and can come in as many as 60 different colors depending upon the design used.
Permeable pavers differ from traditional pavers in several important ways:
- They are thicker than traditional pavers. Permeable pavers are 3 1/8 inches thick (80 mm).
- Traditional, non-permeable pavers are only about 2 3/8 inches thick (roughly 60 mm).
- The secret is the joints. They can vary from between 1/8 of an inch to one half of an inch. These are the spaces that allow the water to filter through.
- The more rainwater you have, the wider the joint.
- Permeable pavers do not use any sand between the joints because it can actually stop the filtration process.
Permeable interlocking concrete pavers, are popular choices for driveways or patios. They are designed to resemble a concrete grid, but their joints are a little wider than traditional pavers. Also, the spaces between them are filled with aggregate designed to allow water filtration. Permeable pavers are only one part of a system that is composed of various layers, including the pavers themselves and several layers of gravel and crushed stones.