Permeable interlocking concrete pavements (PICPs) offer an environmentally friendly way of providing long-lasting beautiful walkways and driveways. They effectively filter and drain stormwater back into the soil, and the availability of many lighter colors can help reduce heat onsite.
What Is Permeable Interlocking Concrete Pavement?
PICP comprises a layer of solid concrete pavers separated by joints filled with small stones (see diagram to the right). Water enters the joints between the pavers and through an “open-graded” base-crushed stone layers with no small or fine particles. The void spaces among the crushed stone store water and infiltrate it back into the soil subgrade. The stones in the joints provide permeability, and the base filters stormwater to help reduce pollutants.
Why Use PICP?
Federal, state, and local sustainable site regulations aim to reduce environmental impacts of increased runoff from roofs and pavements. Past practices for controlling stormwater have included detention ponds for collecting runoff and slowly releasing it into a lake, stream, or storm sewer system. More recent approaches target infiltrating runoff at the site. PICP for patios, walkways, driveways, and housing development roads infiltrates stormwater, reducing or eliminating detention pond requirements. Storm sewer pipes and inlets also can be reduced or eliminated. PICP reduces runoff and pollutants, recharges groundwater, and helps reduce downstream erosion and flooding.
Cost-effective reduced site impact: Besides lowering drainage costs, PICP is a space saver. Pedestrian and vehicular pavements are combined with detention areas.
PICP is made with high-strength compressed concrete that resists abrasion, freeze/thaw damage, and degradation from deicing salts. In the coldest climates PICP does not heave and remains stable during freeze/thaw cycles.
PICP can be plowed like any other pavement. Build-up of ice is practically eliminated because the snow melts and drains into the permeable surface and doesn't refreeze into ice.
PICP can be mechanically installed, saving construction time and money. The units are immediately ready for traffic because there's no waiting for curing.
PICP comes in a range of shapes, colors, textures, and patterns to complement any home and enhance neighborhood appeal.
PICP can provide 20 to 25 years of service when carefully constructed and maintained.
Low Impact Development
Many municipalities are turning to low impact development (LID) concepts to reduce environmental impacts and conserve water and air resources. A cornerstone to LID is onsite infiltrating stormwater. PICP can be a key component for reducing runoff in residential LIDs and in high-density residential and commercial redevelopment.
A growing number of guidelines for sustainable homes and buildings are available. These guidelines include LEED, GreenGlobes, and the National Association of Home-builders National Green Building Standard.
ICPI offers resources on PICP design, specification, construction, and maintenance through the Permeable Interlocking Concrete Pavements manual. Project owners and designers are encouraged to use ICPI-certified contractors experienced with PICP construction.
For more information, contact the Portland Cement Association at 5420 Old Orchard Road, Skokie, Ill. 60077. Call 847-966-6200 or visit www.cement.org.