Guide
Pervious Q&A
Contractor Certification | |
Pervious Concrete Pavement...
Pervious Pavements for a More Livable
Environment
|
Pervious pavements are less able to absorb and
store heat than conventional pavements. The lower density of the material (15 -
25% void spaces) reduced heat storage capacity. The lighter colors of some
porous pavement systems reduce the heat absorbing capacity of the pavement. The
open void structure in the porous pavement allows cooler earth temperatures from
below to cool the pavement. These factors allow porous pavement systems to
approach natural ground cover in heat absorbing and storage capacity. |
 |
| Unlike traditional concrete or asphalt, pervious pavements
typically provide a void content of 15-25%, offering improved filtration and an
enormous amount of surface area to catch oils and chemical pollutants. Some
experts believe that the
bacteria living in these spaces break down pollutants preventing much of the
polluted runoff that normally occurs with traditional pavements. Parking lots,
in particular, hold a tremendous potential for this material because of the
amount of oil and other hydro-carbon liquids that seep from parked cars. |
| Pervious pavements can be made of
concrete, asphalt, open-celled stones, and gravel, that are mixed in a manner
that creates an open cell structure allowing water and air to pass through.
Certain types of porous pavement can pass 3-5 gallons of water per minute, which
is far greater than most conceivable rain events and highly effective in
controlling stormwater drainage. |
 |
Because pervious pavements allow rainwater to seep into the
ground through the pavement:
 | Vegetation is watered, reducing
the need for irrigation |
| Ground water is recharged |
| Water resources are preserved |
| Stormwater runoff is reduced |
| Stormwater runoff quality is
improved |
|
|
The strength and durability of pervious pavement appears to be
equal to traditional materials. There are several examples of parking lots built
more than twenty years ago with pervious pavement that are still structurally
sound and in use. Pervious pavement is also less susceptible to freeze-thaw
cracking, due to large void spaces. |
 |
|
Concerns about clogging of pervious pavements can be
"designed out", by reducing erosion and sediment
runoff through strategic design and water retaining ground cover. Studies
indicate that pressure washing a "clogged"
pervious concrete pavement can restore 80-90% of the permeability. |
|
A new mind set is needed when designing stormwater management
systems. Rather than designing a system to pass huge storm events (that may
occur only twice a century) rapidly from an area, water management planners
should consider the benefits of capturing and recharging water from the smaller,
more frequent rain intervals. Atlanta, for example, receives significantly more
than half its annual rainfall from precipitation events of less than an inch.
The ecosystem lives and dies on daily events. A stormwater system incorporating
pervious pavement will be much more effective in reducing total runoff and
increasing the amount of filtered groundwater. The material's
ability to retain stormwater while improving water quality and enhancing tree
and vegetation growth, makes this material a very exciting example of green and
sustainable building practice.
The American Concrete
Institute (ACI) has recently published document ACI 522R-06 on pervious
concrete.
|
For more information, contact:
John Love, P.E.
Director of Technical Services
GC&PA
100 Crescent Centre Parkway
Suite 110
Tucker, Georgia 30084
770-621-9324
Or visit the following website:
www.pervious.info
|
