Flexible polyethylene forms were erected to outline the circular shape of the display pads in front of the building. Workers finish one of the pads, which has been compacted below the form top.
Flexible polyethylene forms were erected to outline the circular shape of the display pads in front of the building. Workers finish one of the pads, which has been compacted below the form top.

The new Concours Motors BMW dealership in Milwaukee, Wis. has a sleek European feel. Designed by Lynn Bichler Architects, Shorewood, Wis. and built by the Jansen Group, Inc., of Milwaukee, it is meant to be unlike other auto dealerships.

Set close to the street, it makes a bigger impact on potential customers driving by, with only a few display vehicles in front instead of a typical sea of cars. In addition, the dealer is trying to associate the luxury car with the latest in environmental technology. Its newly remodeled façade—white metal paneling with extensive glass storefront areas and curved roof sections—features a stainless steel screen that adds flair while helping to reduce heat gain.

Closeup shows finished pad and adjacent walk.
Closeup shows finished pad and adjacent walk.

In keeping with the building's cutting edge environmental theme, another state-of-the-art technology to impress the luxury car buyer concerns the concrete on which the cars rest. The display vehicles out front sit on 10 circular pads made with pervious concrete. The pads help manage stormwater runoff and eliminate the need for retaining ponds. Constructing the 20-foot diameter pads was made easier with reusable Poly Meta Forms.  

These reusable polyethylene forms are strong, yet lighter to handle than wood, easier to stake accurately, and available for use on straight or radius applications. Their ability to handle circular shapes made the job easier than using wood. “We figured the square footage and diameter, and the perimeter came out to a certain length, so we just cut it and put it together,” says Mike Kies, concrete finishing superintendent for the Jansen Group.

The pads themselves rest on 18 to 24 inches of gravel, creating a retaining pond beneath the surface that allows rainwater to seep slowly into the ground. The pads were poured one or two at a time because of the added hand labor required with the pervious mix and the need to closely monitor water content. When the material was delivered, it was considerably thicker than conventional ready mix and often had to be shoveled into place. Kies explains, “We were pouring it at a 1.5-inch slump and leaving it high in the forms.” Then it was covered with plastic sheeting for a short time to stabilize water content. Once the plastic was removed, a plate compactor was used to compact the material. A hand roller also was used to compact the mix, and final hand finishing helped to achieve the desired surface. The pavement was then sprayed with water and covered with plastic film to cure.

Removing the forms was easy. Kies says, “You just pull the pins and pull them off. It's faster and easier than pulling nails from wood forms, and they're lighter than 2x4s.”

As with most urban projects that require extensive paving, handling of stormwater runoff was a concern. Here, the Milwaukee Metropolitan Sewage District approved the use of pervious concrete over a deep gravel base to accumulate and manage rainwater.

This concrete was specified to minimize runoff into the city's storm sewer system, and it made more efficient use of the land than creating a retention pond.

Pervious concrete allows water to flow through virtually unimpeded and percolate into the soil instead of running off. A problem with standard pavement is it doesn't allow water to soak into the ground naturally, where it is cleaned and purified. Instead rainwater and melting snow flow over paved surfaces, collecting engine oil, transmission fluid, metals, bacteria, and garbage.

Most often used for low-traffic, low-speed areas, pervious concrete usually consists of pea gravel, portland cement, and water. Less water is used than with conventional concrete mixes, and it includes no fine aggregate but more cement than usual. This provides a stiffer mixture that is worked more like asphalt than concrete, Kies says.

The concrete is a product of Ecocreto of Texas, headquartered in Austin, and was supplied locally through Zabest Commercial Group, Inc, of Milwaukee. Ecocreto says pervious concrete is as strong as conventional concrete but much better for the environment. Also, because water penetrates quickly and completely through it, surfaces are dry and safe with no standing water.

For more information about using side forms for pervious concrete, contact Metal Forms Corp. 414-964-4550. www.metalforms.com.