AZEK Permeable Pavers endure six years of harsh conditions at University of Minnesota, surpassing performance of traditional concrete pavers
By Carey Walley
Product case studies often examine the potential problem-solving nature of products such as speed of installation, labor savings and the like. But when it comes to performance, it is often expressed by contractors or building managers in terms of expectations for the future, thereby remaining a mystery as to how the product fared months or even years later. In the case of AZEK Permeable Pavers being selected by the University Of Minnesota Duluth (UMD), a paver project was recently revisited six years after the pavers were tested side-by-side with traditional concrete pavers.
The difference of these recycled-content alternatives compared to concrete pavers is clearly visible: no signs of cracks, minimal wear and tear, damage or color change. The concrete pavers, however, had buckled and raised up on one side, showing cracks and wear.
In the fall of 2007, when UMD tested the new paver technology against traditional concrete pavers, the product was a recent invention, available only regionally and through architect spec. In fall of 2011, VAST Enterprises entered a strategic alliance with AZEK Building Products, known for its low-maintenance line of premium, exterior building products. In December 2012, AZEK bought out the company and AZEK Pavers are now available nationally through lumber dealers that carry AZEK products, greatly expanding the market for the pavers.
UMD’s need for a permeable solution came about when they were constructing a new civil engineering building and wrestled with how to manage stormwater runoff on impervious surfaces around the building, being that the campus is located on a designated trout stream that drains into Lake Superior. The university’s Stormwater Pollution Prevention Program (SWPPP) required stormwater treatment so the designer suggested AZEK Permeable Pavers for their water infiltration properties (thanks to spacer lugs on the sides of the pavers) and they’re up to 95 percent recycled content. The pavers are mostly comprised of scrap auto tires, along with some plastics and make it easier to attain LEED points than traditional pavers.
In fact, AZEK Pavers’ manufacturing to date has diverted more than 10 million pounds of scrap rubber and plastics from U.S. landfills utilizing recycled material from more than 535,000 scrap tires and 16 million plastic food containers and DVD cases, the company reports. Additionally, AZEK reports the manufacturing process also uses 95 percent less energy and produces 96 percent less in CO2 emissions than conventional pavers.
For UMD, the big question was how they would perform in sub-freezing Minnesota temperatures, repeated freeze-thaw cycles, the scraping of snowplows, the snow itself and salt used for de-icing. Top it off with heavy truck traffic in a loading dock area and it presented an all-out challenge of a new paver technology versus traditional. Also central to the issue was how AZEK Pavers would manage the rainwater runoff.
According to Mindy Granley, UMD’s sustainability coordinator, the soil has a high clay content and is not conducive to absorbing water. “Rainwater from the campus can get down from the top of the hill to Lake Superior in just 10 to 15 minutes,” she said. Granley pointed out that impervious surfaces can impact water quality and that by controlling the volume and speed of the water flow, pollution and erosion are reduced.
The AZEK Paver vs. concrete paver test was set up in two high traffic areas. The first was a 600-square-foot loading and storage area expansion of UMD’s plumbing shop where truck deliveries are made. Erik Larson, engineer at UMD, said this was an appropriate test area since it had poor drainage and was frequently muddy after heavy rains and had vehicle, forklift and truck traffic. Set into their unique 16 X 16-inch interlocking grids, AZEK Permeable Pavers were installed next to traditional concrete pavers on the same engineered base.
The second area comprised a 75-square-foot triangular area outside the Sports and Health Center, where the unloading of sports teams and student foot traffic took a toll on the area. Despite attempts by the Building & Grounds division of Facilities Management to landscape the area, students kept cutting through the area. It provided a good proving ground to see how the new permeable pavers handled foot traffic in winter conditions.
After a tough Minnesota winter in Spring 2008, UMD deemed the test to be favorable for the new recycled-content permeable pavers. Unlike concrete in the same areas, AZEK Pavers were unaffected, showing no cracks or color fading. The Facilities division went on to complete 990 square feet of pavers in the Civil Engineering building’s loading dock area. UMD also kept the test installation.
Six years later, UMD is still encouraged by the new pavers’ performance in all three locations. Whereas the concrete pavers took more of a beating from traffic and snow and ice control, AZEK Permeable Pavers look more like the day they were installed, UMD reports.
According to Granley, they have proven to be an effective solution to UMD’s soil conditions, as well as standing up to extreme winter conditions – both natural and man-made. Engineer Larson agreed, adding, “We do intend to use the pavers on future projects.”
For more information on AZEK Pavers, visit AZEK Building Products’ website at www.azek.com.
Carey Walley is VP of marketing for CPG Building Products.