FAQ's about Pervious Concrete

Where can I get pervious concrete?

Many ready-mix producers can supply pervious concrete. Contact your local ready-mix concrete association for referrals or find a ready mix supplier in your area. Use The Concrete Network' s concrete association directory to find associations in your state.

Can the voids in the pavement become clogged, and thus ineffective?

It's unlikely that a pervious surface will become totally clogged. Reducing erosion and sediment runoff onto the pavement through good design can eliminate most problems. If any voids do become clogged, vacuuming or pressure washing of the pavement can restore most of the permeability.


The new Eagle Canyon exhibit at the Portland, Ore., zoo features a
rustic pervious concrete pathway winding through a terrain of faux boulders.

Can decorative treatments be applied to pervious concrete pavements?

Many landscape architects like the organic, rough-textured look of plain pervious concrete. But for installers who want to enhance the aesthetics, there are several options. Integral coloring agents can be added to the concrete before its placed. Or water-based concrete stains can be sprayed onto the surface after installation. (Dont use solvent-based coatings or sealers because they can clog the voids in the pavement.) Because pervious concrete is much stiffer than standard concrete, patterns can't easily be stamped into it. But it is possible to score decorative lines into the surface.

How strong is a typical pervious concrete pavement?

It's possible to achieve pervious concrete compressive strengths of 3000 to 4000 psi and flexural strengths of 500 to 600 psi, which are on par with conventional concrete. With the use of admixtures, today's pervious concrete mixes can be made with less water, which improves strength and durability. Also, better placement methods have resulted in tighter pavements that maintain point-to-point contact of all the aggregates while providing the necessary void content.

Can pervious concrete be used in climates exposed to freezing and thawing?

In most cases, the strength and durability of pervious concrete make it resistant to potential cracking from freezing and thawing. According to the National Ready Mixed Concrete Association, pervious concrete that is partially saturated should have sufficient voids to accommodate the expansion caused by freezing of water. Structural damage could occur, however, if the pavement becomes fully saturated or the ability of the concrete to drain water is compromised due to clogging of the void structure. NRMCA offers recommendations for preventing these problems in its publication Freeze-Thaw Resistance of Pervious Concrete.

Can pervious pavements be used over impervious, clayey soils?

Yes, but the pervious concrete should be installed over a permeable subgrade layer of rock several inches thick. This additional layer will allow the pavement to hold more water until its absorbed into the ground. Consult a geotechnical engineer for design and construction options specific to the soil in your area.

What about maintenance?

Generally the only maintenance needed is to occasionally sweep, pressure wash, or vacuum the pavement to remove any debris that might clog the voids and inhibit water penetration.

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