Have you ever felt like the terminology of a subject strands you in an unknown land? Take asphalt -- if you’re just learning about it, terminology can be a barrier. Those in the industry don’t think twice about terms like “hot-mix” or “sealcoating,” but for the layman, these can be confusing.
Pervious and Permeable and Porous, Oh My!
Some terms that often get mixed up are pervious, permeable, and porous. These sound similar, like they all mean the same thing. In fact, if you look up “pervious,” “permeable” is part of the definition! Both mean a substance that allows liquids or gases to pass through (as opposed to being a solid barrier). These terms are also used synonymously in asphalt. Pervious or permeable pavements have connected spaces that allow water to percolate through the surface.
“Porous” has a similar, but slightly different, meaning. Holes or spaces in the surface allow water in, but these are not necessarily connected. While fluids could get in, they have nowhere to go from there and can't easily percolate down to the water table. This distinction, however, is not generally recognized in the industry.
But What Does it Really Mean?
So now you can define the terms, but what do they really mean? If you’re seeing these, you might be looking at stormwater management for your property. Impervious pavement forces water to run off into drainage systems and waterways too quickly. That can cause flooding, and the water can carry a lot of debris and pollutants into those systems. Using an impervious surface could mean you have to take other measures to manage stormwater runoff from your property, such as installing a detention basin. Using a permeable pavement can help reduce your environmental impact and meet regulations for stormwater management.
How Do I Apply This?
When it comes to asphalt, whether you hear “pervious,” “permeable,” or “porous,” chances are that the same thing is meant – a surface designed to allow water to infiltrate instead of running off. However, you might need to clarify with your contractor to be certain they’re using the terms interchangeably. If not, check the stormwater management efficacy of the different types they’re using. Also, check pricing, as prices may vary on the different types of asphalt they offer and your specific job specifications.
Also, download our free brochure that further explains what permeable pavement is.