David White, the Richard L. Handy Endowed Associate Professor in geotechnical/materials engineering, has invented a sewer pipe made of recycled plastic soda bottles, plastic fibers and fly ash.
“America’s infrastructure currently has about 600,000 miles of sewer pipes, much of which is older than 30 years and in need of repair,” White says. “I feel that we must find a pipe made of more sustainable, sewage-resistant materials to accommodate our sanitary needs.” Sulfuric acid, commonly found in sewage, is slowly disintegrating the current concrete sewer pipes in municipalities throughout the U.S.
White’s patented solution combines recycled, post-consumer waste polyethylene terephthalate (typical soda bottle plastic), fly ash (coal remains after use in power plant), and plastic fiber reinforcement. This sewer pipe invention is lighter and stronger than conventional sewer pipe made of Portland cement concrete. White’s solution also has higher structural capacity, is more resistant to acid and is less dense.
The new pipe material is more environmentally friendly, too, which White is especially proud of. “By using recycled soda bottle plastic, significantly less crude oil is used than using petroleum-based virgin plastic.” To test his invention, White gathered 99 percent of the materials locally. Plastic soda bottles came from Iowa State campus bottle collections; fly ash came from burnt coal at the Ames Municipal Power Plant; and plastic fibers (1 percent) were ordered from a supply company.
The research work conducted by White has demonstrated that technology is feasible for making laboratory-scale pipe sections 12 inches in diameter. The next stage in the development process will be full-scale production trials, for which White seeks industry partners with interest in commercializing the technology.
White received a U.S. patent for this “Polymer mortar composite pipe material and manufacturing method” on October 25, 2011.