New Fly Ash Regulations Threaten Sustainable Concrete

(Sustainable Concrete 8-2-2010) 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.
 
Fly ash is not a "filler" material. In fact, in concrete fly ash becomes part of the matrix. It reacts with compounds in portland cement during the hydration process to form new products that are beneficial. Fly ash enhances many concrete properties: fresh workability, improved strength, reduced permeability and therefore increased durability and improved long-term performance. Fly ash also improves concrete’s resistance to premature deterioration mechanisms such as alkali-silica reaction, sulfate attack and corrosion to name a few.
 
In December of 2008 a dike containing a 40-acre coal ash storage pond at the Kingston Fossil Fuel Plant in Kingston, Tennessee failed. This resulted in a release of about 5.4 million cubic yards of coal ash into the Emory River, smaller tributaries and ponds. The spill covered more than 300 acres of land, damaging homes and causing significant damage to the ecosystem in the area. It’s considered the worst spill of its kind in the U.S. and estimates for clean-up costs range from $525 million to $825 million.
 
The failure of the dike at the Kingston plant has triggered the Environmental Protection Agency to more closely monitor and regulate the storage and use of alternative concrete binders such as fly ash.
 
On June 21, the EPA published two potential rulings that would fall under the Resource Conservation and Recovery Act. Two options have been presented and are currently out for public comment for a 90-day period. In the first option these materials would be classified as “special wastes” and the ability to regulate these materials (e.g. management and disposal) would fall under federally enforced requirements. The second option would involve the EPA setting performance standards for the management of these materials and enforcement would come through citizen-based law suits. Under both options materials such as fly ash could continue to be recycled into components of other materials such as concrete. More information can be found via the EPA.
 
But part of the concern of the proposed legislation is that classifying a material as a "special waste" comes with a certain public stigma associated with its continued use. Furthermore, under the second option, enforcement of standards that are driven by lawsuits could eventually lead to the removal of materials such as fly ash for beneficial use, resulting in even more of it ending up in landfills. Ultimately the burden of increased regulation on storage of these types of materials will land in citizen’s electric power bills.
 
Fly ash has a long history of success in many applications. We should be working to increase beneficial uses of fly ash and other materials that contribute to more sustainable concrete and keep more of them out of landfills. This effort is not at odds — or at least it should not be — with the increased movement toward alternative forms of energy that will not be reliant on non-renewable resources such as coal.
 
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).