- Interest in permeable concrete — primarily its ability to prevent devastating damage caused by stormwater runoff — has skyrocketed due to a recent video demonstration in which a parking lot paved with a product called Topmix Permeable absorbs more than 1,000 gallons of water in a minute.
- Products like Topmix Permeable are applied over a base layer of gravel and, depending on the permeability of the substrate, the water is allowed to either permeate the ground below or is diverted elsewhere, over a period of time, through a series of pipes.
- However, the empty spaces in the permeable concrete, which allow water to flow through, have limited the product's use in more rigorous applications, like heavily-traveled highways, and have raised questions about possible damage from freezing water.
According to Lafarge Tarmac, producer of the popular video and manufacturer of Topmix Permeable, stormwater routinely overwhelms older U.S. wastewater systems, causing untreated sewage to be dumped into local waterways and onto public beaches and creating a significant source of pollution for rivers, streams and reservoirs around the world.
Proponents of permeable concrete also call it a "green stormwater management strategy" because the concrete can both absorb and clean the water instead of overwhelming sewer systems, as well as irrigate surrounding areas.
As concerns of overwhelming amounts of stormwater negatively affecting construction projects grow, permeable concrete could offer builders a possible solution. The limitations of the concrete, however, have kept it from more widespread use.