Fly Ash Forever
The use of fly ash as an ingredient in concrete steadily increased for many years, mostly due to the benefits fly ash imparts to the qualities of hardened concrete—higher strength, reduced permeability, lower heat of hydration, and lowered susceptibility to alkali-aggregate reactions. With the desire to make concrete more sustainable, fly ash found a new niche: since it reduces the quantity of portland cement in a mix It also reduces the carbon footprint associated with that mix, making concrete more sustainable.
But in 2009, with the failure of a major fly ash disposal facility, the EPA was threatening to declare fly ash a hazardous waste, which would have thrown into question its use in concrete. The uncertainty created by this potential designation reduced the use of fly ash in concrete. But the concrete industry fought this designation with a unified approach and on December 19, the EPA released its final ruling, declaring fly ash non-hazardous and encouraging “beneficial use,” such as in concrete.
This is an important victory for our industry–and for the environment. There was never a logical reason for making fly ash a hazardous waste and with EPA’s agreement, fly ash use in concrete should come back to and surpass 2008 levels, reducing greenhouse gases and the quantity of fly ash being placed in landfills. Tom Adams, with the American Coal Ash Association, says, “Millions of tons of coal ash will continue to be generated in the U.S. every year. With disposal regulations finally settled, we can refocus energy on productively using those large volumes of materials rather than throwing them away.”
By Bill Palmer