I am always sucker for a good YouTube video, especially if it is transit oriented. I am mesmerized by the below video demonstrating the effectiveness of pervious concrete. It is simply stunning how the concrete disperses all the water and seemingly not a single drop makes it to the side of the road.
I’ll let the National Ready Mixed Concrete Association explain how it works.
In pervious concrete, carefully controlled amounts of
water and cementitious materials are used to create a paste that forms a thick coating around aggregate particles. A pervious concrete mixture contains little or no sand, creating a substantial void content. Using sufficient paste to coat and bind the aggregate particles together creates a system of highly permeable, interconnected voids that drains quickly. Typically, between 15% and 25% voids are achieved in the hardened concrete, and flow rates for water through pervious concrete are typically around 480 in./hr (0.34 cm/s, which is 5 gal/ft min or 200 L/m, although they can be much higher. Both the low mortar content and high porosity also reduce strength compared to conventional concrete mixtures, but sufficient strength for many applications is readily achieved.
While pervious concrete can be used for a surprising number of applications, its primary use is in pavement. This site focuses on the pavement applications of the material, which also has been referred to as porous concrete, permeable concrete, no-fines concrete, gap-graded concrete, and enhanced-porosity concrete.There is more info on the linked website to explain the science of pervious concrete, how it is made, how it is poured, how it is maintained, and its many benefits.
The Daily Reporter wrote about a recent construction project in Shoreview, MN where the construction was paved with pervious concrete. The material is admittedly not cheap, but by using a system that prevents run off it also saves costs in various other infrastructure like storm drains.
The pavement isn’t cheap; its upfront cost is about 50 percent more than traditional concrete, Lee said. But he added that it’s cost-effective considering that “you are getting a storm water management system” instead of just a driving surface.
“When you net out what you don’t have to build — mainly ponds and piping and catch basins and manholes — when you consider the cost of those things, it is almost a break-even,” Maloney said. “We would not be doing the project if that weren’t the case.”
As more contractors become familiar with the product, and learn how to apply it with the proper tools and techniques, the price is likely to fall.
There are obvious questions about how the pavement will keep when the weather freezes, so the technology may be better suited for Florida than North Dakota. Regardless, I am excited about any product that can reduce the amount of infrastructure needed and save space while accomplishing the same functions as older systems.