Essentially, pervious concrete is a structural concrete pavement with a large volume (approx. 20%) of interconnected voids. Like conventional concrete, it is made from a mixture of cement, coarse aggregates, and water. However, it contains little or no sand, which results in a porous open-cell structure that water passes through readily.

When pervious concrete is used for paving, it can take in stormwater at a rapid rate of over one thousand inches of water per square foot per hour, which far exceeds the flow rate needed to prevent runoff in even the most severe rain events.

The rainwater is temporarily stored in a coarse gravel layer underneath the pavement while it is allowed to naturally percolate into the underlying soil. Because the pavement and base layer act as a retention area, it helps to prevent much of the polluted runoff that normally occurs with impervious pavements.

The filtration process also helps to purify the water. As the water percolates through the open cells of the pavement, aerobic bacteria in the voids help to break down harmful pollutants and chemical.

At Bay Area Pervious Concrete, we have proprietary mix designs that we use to customize pervious concrete for the variable conditions that San Francisco Bay Area site conditions bring. We can design the optimal mix design for your site and conditions. Contact us for more information.