Fly Ash: Green Building Material, Hazardous Waste?

My first legal case involved "fly ash."  I had no idea what fly ash was so I looked it up in the dictionary.  Fly ash is a "coal-combustion by-product" (CCB) that is often used in concrete as a replacement for portland cement.  When used in massive concrete structures, like dam construction, fly ash can result in a significant cost savings.  

Despite all of my work with fly ash, I had never read or heard anyone mention that fly ash could be the "new asbestos."  That was, until I read an ENR article titled "Fly Ash Looms as the 'New Asbestos":

"Concrete groups are on tenterhooks, waiting for the U.S. Environmental Protection Agency to publish a proposed rule that aims to designate fly ash and other coal-combustion by-products as hazardous waste. The concrete sector is concerned even about the ramifications of a 'hybrid' rule that would allow beneficial uses of CCBs to continue."

But what does fly ash have to do with green building?  According to the Portland Cement Association, fly ash can be used in green buildings to achieve an innovation point:
"[T]he USGBC has issued a credit interpretation that allows for an innovation credit if 40% less cement is used than in typical construction, or if 40% of the cement in concrete is replaced with slag cement, fly ash, or both."
A ruling that fly ash is a hazardous waste could reduce the amount of the material used in future construction.  Additionally, handling of existing structures that contain fly ash will become more complicated and costly.  

What do you think?  
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Comments (4) Read through and enter the discussion with the form at the end
Tony - May 3, 2010 10:40 AM

I believe anything with ties to the coal industry will come under close scrutiny during this administration. President Obama has publicly stated that he intends to bring the coal industry to its knees. This is only the beginning. Thanks for your concise and informative articles. Yours are one of a handful that I read regularly.

mgil - May 5, 2010 11:13 AM

Interesting post. The reason fly ash is considered green is because the production of portland cement is extremely energy intensive, therefore by substituting portland cement with fly ash you reduce the carbon footprint of the concrete. I have also been told that it makes the concrete harder.

My question is; once the concrete has cured, is there a health risk for the occupants of the building?

Its too bad the article you reference is not free.

GreenBuilder - September 23, 2010 2:41 AM

Wake up Green Builders!

I am amazed that the coal industry has managed to brainwash so many.

Here's the truth:

- Coal ash is definitely toxic (lead, mercury, arsenic, dioxin, and the list goes on and on...)

- Over 130 million tons of toxic coal wastes/year are generated nationally (according to the coal ash trade association - there's no independent data)

- According to the U.S. Energy Information Administration, coal is responsible for 81% of the CO2 emissions produced by electricity generation (over a third of total U.S. CO2 emissions). Concrete is responsible for less than 2% of US GHG emissions.

- Thus, subsidizing coal through fly ash sales encourages way more GHG emissions than displacing prtland cement ever will. Cement emissions are nothing compared to coal and burning coal -- the source of all fly ash.

- With NO TESTING, LABELING, OR OVERSIGHT, the coal industry sells over 50 million tons of coal wastes into consumer and building products (toothpaste, auto bodies, cosmetics, counter tops, grout, paint, stucco, drywall, ceiling tile, carpet backing) were the toxics are re-released in production or in our products and buildings.

- They even have the nerve to claim it's "beneficial" to spread toxic coal waste on agricultural fields, and dump it loose in waterways and on roads as de-icer.

- The toxics in coal waste are becoming even more concentrated as new air pollution controls are put in place so some concrete made with fly ash won't harden properly.

- "Recycling" (or better yet tox-cycling) toxics into our homes, products, and communities is a BAD idea.

- Allowing hazardous coal waste to be sold instead of managed as hazardous waste is a HUGE subsidy for dirty coal and it puts renewable energy at a great disadvantage.

Wake up Green Builders!

Garrett - January 21, 2011 11:08 AM

The website '' has hundreds of pages published by students at various universities. These papers are the result of research and experiments on the effects of fly ash on concrete as well as the effects that its use in building materials has on our environment. It is a wealth of knowledge, and should be consulted when forming an opinion in regards to use of fly ash in construction.

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