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Infinitely Renewable: Imagining a World Without Waste
There's a dirty little open secret about recycling: Often as not, the more times you recycle a material, the lower the value of the final product-think twenty-pound bond, newsprint, and blown in insulation
It doesn't have to be that way, says Michigan Tech's Tom Van Dam, an associate professor of civil and environmental engineering. It especially doesn't have to be that way with the biggest products America produces: the highways, bridges, and other massive edifices that make up the nation's infrastructure.
Van Dam and his colleagues want to recycle industrial residuals-detritus, such as slag, that's the inevitable result of the production process-and use it to make the building blocks of infrastructure: first-rate asphalt, concrete, and aggregate. Industrial residuals have long been incorporated into these products, but some applications have been more successful than others.
That's because we don't know enough about industrial residuals, according to Van Dam. "Our current way of classifying residuals is inadequate," he says. "For example, every fly ash is different. It can be the best or the worst choice for an application."
If those industrial residuals could be thoroughly studied, then engineers could pick the perfect one to use in making, for example, concrete pavement, without fear that the road would disintegrate after one bad winter and a few overweight trucks. And they'd need to mine less raw materials, such as sand and gravel, conserving natural resources and protecting the environment.
Finding money to do that kind of broad-based research on industrial residuals hasn't been easy, Van Dam notes. However, a four-year, $2.0- million federal grant is making it possible.
Michigan Tech has been named a University Transportation Center in Transportation Materials, qualifying it for the funding. It is one of only thirty federally designated UTCs, and the only one specializing in materials.
"I look at it as a gift," Van Dam says. "It's a great opportunity to bring our current program, which is a leader in Michigan, to the national level."
While the program will focus on materials, including industrial residuals, it will also encompass sustainability, looking at the entire life-cycle of the transportation infrastructure.
"We're very enthusiastic about sustainability," Van Dam says. "People think it's tree-hugging, but really it's just good engineering. It's taking a long-term perspective on your materials choices. If you're not incorporating sustainability in engineering, you are missing a very important factor."
There has been some cynicism about sustainability in the transportation materials field. "The fear has been that roads would become linear landfills," Van Dam says, with pavement getting worse and worse as waste replaces quality ingredients in asphalt and concrete. "We're not talking about that. We're talking about making our existing systems better through the use of new materials that at one time might have been discarded."
The industry is already moving quickly in that direction. "There is huge potential," he says. "The large cement producers are embracing sustainability, as are concrete producers, as are asphalt producers. Those who don't will be out of business."
Sustainability goes beyond the choice of materials. It can also involve brand-new ways of looking at very old problems. "You could have sensors imbedded in the pavement that detect cracking from beneath, so you could repair a road with a one-inch overlay and save yourself the cost of replacing it a year later."
"You could use nanotechnology to make smart structures," he says. "What if you had little robots the size of sand grains—or smaller—that could sense and repair cracks in concrete or asphalt?"
Ultimately, however, sustainability is about doing the right thing. "We civil engineers need to recognize that our job affects the environment, and we need to ask ourselves how to build the best possible systems," Van Dam says. "If we don't achieve sustainability as a species, we won't survive."