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7 Reasons Porous Asphalt Is Popular For Parking Lots

by Tara Pena

Porous asphalt has become a popular pavement option for parking lots since the 1970s. One well-known porous asphalt parking lot is found at Massachusetts' Walden Pond State Reservation, and the lot was paved in 1977.

Here are seven reasons contractors keep using this type of pavement:

Functionality

The porosity of this special pavement allows water to seep through instead of sitting on the surface. The drained water permeates the stone bed beneath the asphalt and is eventually absorbed into the underlying soil.

Cost Efficiency

Porous asphalt is not as inexpensive as typical asphalt. However, its ability to manage storm water alleviates the need for more expensive drainage systems. Also, no additional land is needed for a retention pond or other drainage feature.

Longevity

Porous asphalt pavements typically last more than 20 years. The Massachusetts lot mentioned above is still referenced because of its lack of structural or drainage problems.  

Appearance

Porous asphalt does not look dramatically different from a typical asphalt surface. It does tend to be a bit coarser, but few people would realize the difference in surfacing. 

Flood Prevention

Porous asphalt solves the problem of standing water that could cause flooding or other types of water damage. In addition, the filtration system of the asphalt can improve water quality by removing contaminants as the water drains through the stone bed beneath the asphalt.

Temperature Control

Like stones in a sauna, asphalt tends to absorb surface heat. However, porous asphalt is more loosely packed than typical asphalt. The additional air space between the stones helps keep the temperature of the pavement lower on hot summer days. 

Few Special Considerations

For the most part, the use of porous asphalt does not have numerous restrictions or special considerations. However, there are a few things an asphalt paving contractor would need to keep in mind when selecting this special pavement.

  • Stone Bed Depth: The stone bed beneath the asphalt must be deep enough to prevent the storm water from settling on the asphalt for prolonged periods. If the stone bed, which is typically between 18 and 36 inches, is too shallow, the drainage feature may be compromised.
  • Asphalt Composition: The pavement's mix is slightly different from that of other asphalt pavements. Nevertheless, most asphalt mixers can prepare it easily, and no special equipment is required for its installation.  
  • Environmental Precautions: Due to the absorbent nature of the asphalt, it may not be installed in areas where hazardous materials are regularly stored or loaded.

Porous asphalt continues to be a great option for parking lots and other paved surfaces that require drainage. The pavement is less expensive than other drainage options and still presents the look of standard asphalt.

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