A completed section of path shows the color and smoothness of the finish. Water percolates through the pavement into the ground, where it is returned to the water table naturally.
The new environmentally friendly pavement, called FilterPave™, combines a durable and decorative surface with porosity that minimizes runoff by quickly percolating stormwater into the ground or an underground storage system.
Recycled Glass Key Component Although various kinds of porous pavements have been around for more than 25 years, the FilterPave system is the first to use recycled glass as one of its components.
Presto Geosystems, Appleton, WI, and Kaul Corporation, Lakewood, CO, designed the patented FilterPave pavement for driveways, parking lots, walkways, golf-cart paths, landscaped areas, or anywhere else that needs to combine a smooth, hard surface with environmentally friendly stormwater control.
Presto Geosystems Director Bill Handlos, P.E., says that Presto chose recycled glass as a main component because glass meets the application’s physical requirements and is plentiful everywhere at low cost.
"A bottle manufacturer usually wants recycled glass in just one trademark color," he says, "so recycled glass of mixed color often ends up in landfills.
We know how to turn that unwanted glass into aggregate for FilterPave porous pavements."
Handlos says the recycled glass undergoes a special process to round its edges and reduce the particles into specifically sized and shaped "glass aggregate" that is harder than stone aggregate but no more brittle when bound. The recycled glass is supplied through certified glass suppliers.
Structure Combines Strength With Porosity The FilterPave system’s other key ingredients are an open-grade clear-stone base course, small various-colored granite and the tough but flexible elastomeric glue that binds the glass-and-granite surface layer together, yet leaves it porous.
Although the binder is strong, it is safe for use around plants and animals.
The elastomeric binder, granite chips and glass aggregate set up strong and hard, with a top surface that’s smooth, like finished concrete, and an inner structure that is about 38 percent porous.
The depths of the base course and the top layer are matched to each application’s water-handling needs and strength requirements. Handlos explains,
"Usually, a top layer and base deep enough to hold and pass the required amount of water will also provide more than enough pavement strength.
But if needed, one or both layers can be deepened to make the pavement even stronger."