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Fly Ash Reuse Takes Off
Fly ash reuse has taken flight at Wisconsin’s Waukesha County Airport. By using this byproduct from burned coal in its new runway, the Airport was able to lower the cost of its runway replacement by $50,000—all while protecting the environment.
Once thought of as a waste from coal-fired power plants, fly ash, a coal combustion byproduct (CCP), has proven to have many of the same properties of the materials it can replace. It can be used as a replacement for or supplement to Portland cement for concrete. It can also be used in embankments, in roadways and bridges, and for soil stabilization. CCPs, in general, add significant environmental, economic, and performance benefits to construction projects. For example, using one ton of fly ash as a replacement for cement:
- Reduces the equivalent of two months of an automobile’s carbon dioxide emissions.
- Saves enough energy to provide electricity to an average American home for 19 days.
Mixing fly ash with recycled asphalt pavements contributes to stronger and longer lasting surfaces than those made with recycled asphalt alone. Strength and durability is key for Waukesha County’s runway that takes on more than 270 airplanes everyday. Fly ash also improves workability, reduces permeability to moisture, and adds greater resistance to deterioration from overuse or bad weather.By using fly ash and a construction method where pre-existing asphalt and base material are recycled to make the new runway, the cost of runway replacement was lowered by $50,000, a 25 percent saving.
Lafarge
North America 
,
a construction supplier, provided the fly ash. Lafarge educates
its industry peers about the positive aspects of fly ash through
workshops held around Wisconsin. Engineers, contractors, and
even administrators learn about the engineering, managerial,
economic, and environmental benefits of fly ash. By educating
their colleagues, Lafarge was able to reuse and recycle more
than 75,000 tons of fly ash in 2006.
Jim Rosenmerkel, an engineering consultant to Lafarge, is optimistic about the expanding use of fly ash. “The technology is certainly still in its infancy, but every year we are gaining knowledge and experience.” As we move forward I think one obstacle to overcome may be a greater demand for fly ash than there will be supply,” said Rosenmerkel.
The beneficial use of fly ash and other CCPs exemplifies the type of reuse of industrial products encouraged by the Resource Conservation Challenge within the national priority area of Industrial Materials Recycling.
For More Information:
- Resource Conservation Challenge national priority area: Industrial Materials Recycling.
- Coal Combustion Product Partnership (C2P2) - C2P2 is a cooperative effort that promotes the beneficial use of coal combustion products (CCPs), as well as the environmental benefits that result from their use.
- Industrial Materials Recycling: Managing Resources for Tomorrow | PDF Version (2 pp, 1.4MB, about PDF)
- Using Coal Ash in Highway Construction: A Guide to Benefits and Impacts (50 pp, 2.3MB, about PDF)
- Lafarge
North America.