Fly ash is a by-product of coal combustion. It can be reused in concrete production as a supplementary cementitious material.
“It is kind of ironic that it is a coal combustion by-product, but it reduces the carbon footprint of concrete overall,” said Eric Misenheimer, technical service manager at Chandler Concrete Company, Inc., based in Burlington.
According to Misenheimer, when coal ash is added to the concrete-making process, it reduces the amount of Portland cement that is needed. Misenheimer said that by eliminating some of the Portland cement, less energy is used in the process and the production is “much more environmentally-friendly.”
Chandler has nearly 40 plants and they have been using coal ash for nearly 40 years.
“It is much easier to obtain, and much cheaper to obtain and use, and it produces a better concrete,” said Misenheimer.
Chandler supplied some of the concrete manufactured with coal ash that was used to build the Proximity Hotel in Greensboro. Hotel owner Dennis Quaintance had the overarching goal of sustainability. Coal ash fit perfectly into the building plans, said Quaintance.
“If you have got a by-product that you don’t know what to do with, figure out how to use it productively,” he said.
Proximity Hotel used 224,000 pounds of coal ash in the concrete of the building’s structure and façade, according to Quaintance.
“It is completely incorporated into and encapsulated by the concrete, so it is one hundred percent safe.”
Proximity Hotel became the first hotel in the United States to receive platinum LEED certification from the U.S. Green Building Council.