We try to keep our finger on the pulse of best management practices for today’s construction. To us, that happens when quality means/methods balance with an eye toward the environment. Pervious concrete can do both.
Pervious concrete is a wonderful concoction that holds up structurally and is porous enough that water can seep through it and flow back into the aquifer. It has polymers that glue the aggregate together, simultaneously allowing open cells to be formed in the concrete. The top inch filters out particulars such as oil and grease and the storm water flows through.
We had our first encounter with pervious concrete 5 years ago on one of our Florida projects. Since then, we have used it on several more sites. Here’s what we have learned from our experience:
● The product works better on sandy soil, which affords good drainage.
● Some pervious pavements fail because of insufficient drainage, especially in climates that experience heavy winter freezes that harden the ground.
● Shale aggregates in the concrete can break under freeze/thaw conditions, clogging the water flow.
● The selection of aggregate in the sub-base is important, and the curing process is crucial. A seven-day, wet-curing period is what we have learned works best.
Pervious concrete is a Best Management Practice recommended by the Environmental Protection Agency. While it is a little more expensive than traditional concrete, additional cost will be balanced by the reduction or elimination of traditional storm water management systems like retention ponds and sewer tie-ins.