Porous Asphalt Pavements

Porous Asphalt Pavements

POROUS ASPHALT can be used for roads, trails, parking lots and recreational facilities, like this porous asphalt basketball court.

Imagine a parking lot without puddles, a bike trail that requires less salt to keep ice-free in winter, roads that redirect stormwater and filter it back into local aquifers. Porous asphalt pavements can do all this and more.

Porous asphalt pavements with stone reservoirs are a multifunctional low-impact development (LID) technology that integrates ecological and environmental goals for a site with land development goals. They are constructed using the same equipment and techniques as conventional asphalt pavements, and provide a cost-effective means for improving the sustainability of facilities.

How It Works

Porous asphalt pavements have been used successfully since the 1970s and have performed well in all climate zones. A porous pavement system consists of a subsurface reservoir filled with larger stones, topped by one or two layers of porous asphalt. The porous asphalt mix is much like typical asphalt mixtures except that it lacks finer material, allowing water to flow through the pavement and into the subsurface reservoir where it soaks into the ground, reducing or eliminating stormwater runoff from the paved surface. This means porous asphalt pavements can reduce or eliminate the need for traditional bio-retention facilities and extensive piping and storm drains. They can also help increase available space for parking or save green space that may be lost to other stormwater management methods.

Designing a porous asphalt pavement begins with a site assessment to characterize the permeability of the surrounding soils. Porous pavements should be constructed over soils that can infiltrate at least 0.1 inch per hour of rainfall and where bedrock or groundwater are at least two feet below the surface. Once the site is determined to be appropriate, construction is similar to traditional pavements.

Suggested Maintenance

Once a porous asphalt pavement is completed, maintenance and upkeep differs from traditional pavements only slightly. The biggest difference is that porous asphalt pavements should not be sanded during winter. Studies at the University of New Hampshire Stormwater Center (UNHSC) have found that there is less refreezing with porous pavements, and a much lower amount of deicing chemicals is needed to melt snow and ice from porous pavements than impervious pavements.

Ideally, porous pavements should be cleaned with a vacuum or regenerative-air sweeper once or twice a year to help ensure the pavement drains as it was designed to. In some instances, power washing may be advisable to clear clogged portions of a porous pavement.

Over their life cycles, porous asphalt pavements tend to not experience the sort of cracking issues that can manifest with other pavement types. This can mean reduced life-cycle costs thanks to reduced need for crack filling or patching. UNHSC has found porous asphalt pavements to be one of the least expensive stormwater best management practices (BMP) to maintain.

Because of how water filters through a porous pavement and its reservoir, runoff from parking lots is reduced or eliminated. But the infiltration action also helps trap pollutants — particularly hydrocarbons, metals and suspended solids — and can improve water quality. Reduced demands for deicing chemicals also helps ensure better water quality.

The Environmental Protection Agency (EPA) classifies porous asphalt pavements as a “cool pavement” technology. The evaporative cooling effect means porous asphalt pavements can have lower surface temperatures than impervious pavements, and they can play a role in mitigating the urban heat island effect. For these reasons, porous asphalt pavements are an EPA-approved BMP for stormwater management.

This article originally appeared in the issue of .

About the Author

Kent Hansen, P.E., is director of engineering for the National Asphalt Pavement Association and a nationally recognized expert on porous asphalt pavements. For more information about porous asphalt pavements, visit www.porouspavement.net.

Featured

  • ClassVR Wins Tech & Learning Best of Show at ISTELive 25

    Avantis Education recently announced that its flagship product, ClassVR, won the Tech & Learning Best of Show Award at ISTELive 25 in San Antonio, Texas, according to a news release. The program is designed to celebrate products that are “transforming education in schools around the world and that show the greatest promise for the industry,” and this is the fourth consecutive year that Avantis has claimed the award.

  • Mesa West Capital Provides Loan to Refinance University of Georgia Residence Complex

    Mesa West Capital recently announced that it has provided a $133.9-million, short-term, first mortgage loan to developer LV Collective (“LV”) to refinance a student housing complex near the University of Georgia, according to a news release. Rambler Athens, a 750-bed residence hall adjacent to the campus, was completed in August 2024.

  • Spaces4Learning Launches 2025 New Product Awards

    Spaces4Learning is now accepting entries for the 2025 New Product Awards! The program’s goal is to honor the outstanding product development achievements of manufacturers and suppliers whose products and services are particularly noteworthy in helping to improve K–12 and Higher Education learning environments.

  • Gretna East High School

    Gretna East High School

    Established in 1999, the Education Design Showcase is a vehicle for showing off innovative — yet practical — solutions in planning, design, architecture, and construction. Gretna East High School has been recognized with an EDS 2025 Project of Distinction award in the category of New Construction.

Digital Edition