These hollies and a fern took root and grew in a spongy material originally designed by an aerospace engineer for use in military aircraft fuel tanks. (Texas Cooperative Extension photo by Mike Jackson)
(Dallas)—North Texas researchers plan to determine whether a spongy material designed to contain jet fuel can be used as bedding for rooftop gardens.
Three scientists are working on a research grant proposal to evaluate the material, which was invented by an aerospace engineer for the defense industry, said Wayne Mackay, a horticulture researcher with the Texas A&M University System Research and Extension Center in Dallas. Mackay has teamed up with two other Dallas-based researchers, Raul Cabrera, a horticulture researcher, and John Sloan, an environmental soil scientist.
"I think we can come up with a research project that we can get real money for," Sloan said.
If they land a grant, their research would focus on a material that looks and feels like foam rubber. It was invented by Joe Byles, who designed the foam for fuel tanks in the wings of military aircraft.
"We were looking at a material to stop fuel from sloshing around in the wings," Byles said.
Though it resembles foam from a seat cushion, the material's characteristics are significantly different. Unlike common foam, its pores are all dodecahedrons whose 12 faces trap both water and air, Byles said.
"The water is in there, but it's not held tightly," he said.
Byles, who is also a Texas Master Gardener, thought the material also would be a good medium in which plants might grow. He was right. Grass, shrubs and trees take root and grow in the material, which Byles now sells commercially under the name Grow Foam.
Mackay said he learned about the material a few years ago. But at meeting in Arizona last May, he and Byles talked about its potential for green roofs. Scientists in both the United States and in Europe are looking to green roofs to replace plants and trees lost to urban development. These rooftop gardens help the environment by consuming carbon monoxide and cooling metropolitan areas during the summer. They also help insulate buildings.
Byles' foam could be a good alternative to conventional roof gardens, Mackay said. It wouldn't require structurally reinforced roofs to handle soil's weight, and it could be easier to install.
Researchers will first determine how well plants fare in the foam and whether the material can sustain a garden over a long period of time, he said. They also would look for ways to change the foam's properties, if necessary, for long-term use.
While Byles admitted he didn't "understand all of the physics," several scientists said they were impressed by what they heard from him during a recent presentation.
Kevin Ong, a plant pathologist, said he wants to use some foam in an exhibit in his education community garden at the Dallas center.
Jim Heitholt, a soybean researcher, suggested the material might have other applications.
"I don't think we should restrict this to rooftops," Heitholt said. "You should think parking lots too." 