Uniquely, Grasscrete’s patented formers are made of recycled paper pulp. Rather than removing them after the concrete is cured, the 100 percent biodegradable pulp formers slowly begin dissolving after the pour starts. Despite being every bit as durable as a fully poured slab, the Grasscrete system results in 37.5 percent surface and effective void, meaning almost two-thirds of the entire pond surface is open space. This allows the vegetation to truly blanket the concrete surface. In the case of the NREL project, an integral color was added to the mix, making the structure largely disappear altogether. In September 2008, Hurricane Ike destroyed the Town of Jean Lafitte, Louisiana's auditorium while flooding thousands of homes and busi- nesses in Jefferson Parrish. Despite the devastation, the town was de- termined to preserve the auditorium’s landmark location by rebuilding in place. Raising the site out of the floodplain required importing more than nine feet of soil while a pile-supported building was designed for the new 18,000 SF auditorium. Elevating the site so much caused some drainage complications along the parking lot where a steep embank- ment transitions down to a ball field at the original grade. “The slope needed to be stabilized beyond the parking lot because of the steep grade and concerns about erosion,” says Robby Oswald, owner of Bomanite of New Orleans, the contractor hired to resolve the issue. Descending about 7 feet in just 12 feet of distance, rain runoff in Louisiana’s damp climate would likely erode the slope quickly. Once it did, the hill along the heavily trafficked route between Lafitte’s schools and the library would either be an eyesore, dangerous, or both. “Grasscrete was the ideal solution because it allows vegetation to grow within the voids. In this case, it was covered with sod,” continues Os- wald, who along with other Licensees across the country has exclusive rights to this innovative concrete system. “The product is backed by a great company that provides technical support whenever we need it,” says Oswald. “The ability to troubleshoot a project with other Licensed Contractors around the country is always there for us.”
leverage the material’s permeability and durability differently. NREL’s mission is to research and develop clean energy and energy efficiency technologies and related sciences. “As a research laboratory, NREL has been a testing ground for a wide range of pervious concrete systems,” says John Buteyn, Vice President and Technical Manager, at Colorado Hardscapes. “Improving a deten- tion pond on this campus could have long-lasting implications for the way onsite water runoff is managed for generations to come.” Generally integrated into campus settings, detention ponds detain wa- ter onsite to prevent heavy rains from overburdening municipal storm- water systems. Ponds are often planted with wetlands type vegetation to enhance their appearance. As water runs through the pond, a layer of sediment builds up and makes the pond less effective. Once enough sediment accumulates the pond must be scraped; a heavy-equipment process that generally destroys all existing vegetation leaving the need to completely replant the pond afterward. “Grasscrete allows the vegetation to be planted into the concrete so the root systems form below the surface,” continues Buteyn. “When heavy equipment removes the sediment build-up, they can scrape it down to the surface and the plant’s root structures remain intact. This allows it to quickly regenerate without the need for new plantings.”
SEAN O'KEEFE is an architecture and construction writer who crafts stories and content based on 20 years of experience and a keen interest in the people who make projects happen. He can be reached at sean@sokpr.com.
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july 2020
csengineermag.com
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