This week, several of our team attended a workshop led by Matthew Offenberg, a recognized expert in the field of pervious concrete. The discussion centered on the design and function of pervious concrete pavements, new developments in the technology and some of the challenges in implementing it. I found it interesting that the workshop was held here in Birmingham, an area known for its impermeable clay soils.
Our company has experience with pervious pavements in coastal areas with sandy, drainable soils. We will install our first pervious concrete parking lot in this area this month. Apparently, we aren’t the only ones expanding our use of this sustainable method. Factors that have contributed to the spread of the pervious industry to areas not originally thought to be candidates include:
Increased land values. The growing scarcity of suitable building sites have pushed developers and planners to squeeze more out of the site, and getting rid of the detention ponds creates more space.
Availability of materials. Readily accessible and relatively inexpensive crushed stone makes the addition of a “drainable layer” under paving easier in areas similar to Birmingham.
Industry growth. We now have more qualified suppliers and contractors, training programs and continuing education programs. This provides more resources and experience to draw.
As these and other sustainable technologies become tested by time and experience, their popularity will grow. In this instance, sustainable has become practical, and we consider that a success. Here are some pros and cons regarding the implementation and use of pervious concrete:
POSITIVE
- Allows drainage of storm water directly into sub-soils
- Omits the need for expensive retention/detention ponds, saving valuable land space for other uses
- Structurally self-supporting water storage units can be placed under pervious concrete for irrigation use
- Can be placed over tree root systems allowing for limited space traffic use
- Can be placed in run-off buffer zones expanding traffic use space
- Omits need for extensive storm drainage pipe systems as well as curb and gutter
- No reinforcement required
NEGATIVE
- Periodic cleaning required to maintain porosity, but minimal maintenance otherwise
- Relative weakness does not allow for heavy truck traffic
- Some raveling may occur over time, especially along edges—may require regular concrete ribbon along edges
- 6” minimum thickness for light duty traffic
- Requires substantial porous substrate for positive drainage
- Must be kept covered and barricaded for a minimum of seven days after initial installation
- Freeze/thaw spalling can develop in northern climates where there are extreme cold temperatures.
For us, the pros outweigh the cons when it comes to pervious concrete in the right applications—it maybe something to consider when you’re planning your next project. It’s a good option for the environment and an overall value-add.
