LASN is a photographically oriented, professional journal featuring topics of concern and state-of-the-art projects designed or influenced by registered Landscape Architects.
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(Continued on page 18) 18 Landscape Architect and Specifier News Product case studies often examine the potential for problem-solving, considering attributes like speed of installation, labor savings and the like. When it comes to performance, however, most hardscapers have projections for the future of an installation but rarely follow up unless there is a significant problem, thus, the strength and reliability of a product months or even years later remains a mystery. The University of Minnesota Duluth (UMD) set out to dispel some of these mysteries by revisiting a permeable paver project six years after the pavers were installed side-by-side with traditional concrete pavers. In the fall of 2007, when UMD tested new permeable paver technology against traditional concrete pavers, the former was a recent invention, available only regionally and through architect specifications. The difference in comparison to concrete pavers is clearly visible: no signs of cracks, minimal wear and tear, damage or color change. The concrete pavers in the test area, however, had buckled and rose up on one side, and showed cracks and wear. UMD's need for a permeable solution came about when the school began construction on a new civil engineering building and wrestled with methods to manage stormwater runoff on impervious surfaces around the building, since the campus is adjacent to a designated trout stream that drains into Lake Superior. The university's Storm Water Pollution Prevention program required stormwater treatment in new construction, so the designer suggested AZEK permeable pavers for their water infiltration properties, due to the spacer lugs on the sides of the pavers, and as much as 95 percent recycled content in the paving units. The pavers are comprised mostly of scrap auto tires and some plastics, and make it easier to attain LEED points than traditional pavers. The big question was how the pavers would perform in subfreezing Minnesota temperatures, repetitious freeze-thaw cycles, the scraping of snow plows, the snow itself and salt used for deicing. Combined with heavy truck traffic in a loading dock area, the installation presented an all-out challenge between a new paver technology and a traditional installation. Management of rainwater runoff was also central to the case study. h a rd s c a p e s By William Chelak for AZEK Building Products Permeable Pavers Surpass Concrete In Long-Term Test Above The University of Minnesota Duluth (UMD) installed three test sections of permeable pavers on campus next to conventional concrete pavers to test the difference in durability and stormwater management ability in the fall of 2007. When inspections of the surfacing were positive following a harsh Minnesota winter, UMD decided to expand its permeable paver installations. The sustainable stones held up admirably upon subsequent examination more than six years after construction. 18-21.indd 18 2/27/14 9:00 AM