New fly ash regulations threaten sustainable concrete
By Jason Ideker
Oregon State University
Concrete is the most used building material in the world. The only resource consumed in greater quantity is water. For every person on the planet approximately 35 cubic feet of concrete is produced each year.
The manufacture of the main binding agent in concrete, portland cement, accounts for between 5 percent and 7 percent of the world’s carbon dioxide output. Researchers are investigating many ways to reduce the carbon dioxide footprint of concrete from new manufacturing techniques to alternative binders for concrete.
However, while those new technologies are being developed, we already have a vast toolbox at our disposal to reduce carbon dioxide emissions. One of the most common and most effective options is to replace a portion of the portland cement with fly ash (commonly between 25 percent and 50 percent by mass of cement), a by-product of the coal-burning power industry. However, the future of fly ash availability is in question due to new regulations posed by the Environmental Protection Agency.
Fly ash is a coal-combustion product that is used beneficially in many applications, including incorporation into concrete. Since portland cement is responsible for such significant world-wide carbon dioxide emissions, replacing it with a material that would otherwise be relegated to a landfill represents an important step toward improving the sustainability of concrete. It also reduces the burden on landfills.
In 2007, there was a 15-million-ton reduction of carbon dioxide production, according to the American Concrete Institute, thanks to the beneficial incorporation of fly ash in the mix.
Dr. Jason H. Ideker is an assistant pofessor in Innovative Materials at Oregon State University. He is active in committees for the American Concrete Institute and a director of the Green Building Materials Laboratory, a signature research facility of the Oregon Built Environment & Sustainable Technologies Center (Oregon BEST).
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