PERVIOUS CONCRETE
INSIDE THE FLOODPLAIN | OUTSIDE THE FLOODPLAIN

What Is It?

Cost: $2.00-$6.50 per sq ft. Typically 15% more expensive than conventional concrete and four times more expensive than porous asphalt.
Applications: All applications as alternative to conventional concrete, including parking lots, low speed/volume streets, pathways, and other pedestrian applications.
Service Life: 15-30 years

Pervious concrete is concrete mixed with less sand and fine particles than conventional asphalt. The concrete is then laid above a crushed stone aggregate base to allow for water infiltration. Water is able to permeate the concrete due to void spaces of 18-20%, which also reduces the weight of pervious concrete by 20-30% compared to conventional concrete. Rigid pavements like concrete typically do not require aggregate bases for structural stability, though deep aggregate bases are recommended for cold climates like the northeast. Suppliers are easy to find, as pervious concrete is mixed and applied using the same equipment and methods as impervious concrete. The lack of fine particles gives pervious concrete a coarser look than conventional concrete.

As with other pervious pavements, proper maintenance (primarily vacuum sweeping) is necessary to maintain high rates of infiltration. Infiltration rates are also highly dependent on the subgrade soil. Sandy soils have highest infiltration capacity and increased load bearing capacity, but lower treatment capacity. Potholes and cracks can be fixed with patching mixes unless >10% of the surface needs replacement. The maximum slope of pervious concrete exceeds porous asphalt and allows for a slope of up to 12% while maintaining infiltration.

Benefits

  • Enhances groundwater infiltration while reducing stormwater runoff volume, rate, and pollutants.
  • Contributes to lower urban air temperatures when moist due to higher reflectivity and evaporative cooling.
  • Reduces occurrence of black ice/freezing puddles in cold climates; requires fewer applied deicers.

Drawbacks

  • Allows pollutants to infiltrate groundwater. Should not be installed in areas where hazardous material spills are possible.
  • Plowed snow piles and improper deicing treatment can clog void spaces and reduce infiltration rate (sand should not be used). Snow plow blades can damage surface.
  • Coarse appearance can be aesthetically displeasing (relative to conventional concrete).

Regulatory Impacts and Requirements

A summary of potential regulatory touchpoints follows below:
Pervious-Concrete

Financing Options, Incentives, And Rebates

Additional Resources

PROJECT EXAMPLES

SAMPLE OF SUPPLIERS

SOURCES

Photo credit: User PerviousConcrete on Wikimedia Commons