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Fly ash fully replaces Portland cement in this architectural face brick product from CalStar. The result is an 85% reduction in embodied energy and CO2 emissions with no compromise in price or performance.


“Their experiments also found that the amount of mercury that leached out of pulverized fly ash concrete was actually less than the amount that leached from concrete made without fly ash,” he explains.

In general, fly ash products tend to fare well when tested. For example, test results of CertainTeed’s WeatherBoard’s fiber cement siding found that most metals were below detection limits. “For those that were not, the metals were well within regulatory limits and considered safe, passing every test the EPA has published for determining whether a substance or metal is hazardous,” explains Drew Brandt, LEED AP, director of product marketing for CertainTeed’s Siding Products Group in Valley Forge, Penn.

At present, the only EPA-acknowledged test for concrete and brick building products is the Toxicity Characteristic Leaching Procedure where the fly ash concrete is ground up into pea-sized fragments and then soaked in acid. However, the EPA itself has stated that the test was outdated and not the most appropriate way to determine leachability of coal combustion waste constituents, according to Widawsky.

As an alternative, the EPA is currently developing the Leaching Environmental Assessment Framework (LEAF) test, but some industry stakeholders question how fair LEAF will ultimately be as the current platform allows the tester to choose the level of intensity to which the product will be exposed.

“One could apply the most severe testing scenario, which has nothing to do with ‘real life,’ and test a product that way,” explains Julie Rapoport, vice president, product management, CalStar Products, Newark, Calif., whose company manufacturers architectural face brick and concrete and brick pavers with fly ash.

In other words, one could probably leach anything out of any material if it was subjected to severe enough conditions, says Rapoport, but in reality, a brick or concrete façade or walkway would never be exposed to anywhere near such conditions, even collectively throughout its lifetime.


While the controversy over fly ash safety seems relatively new, the use of fly ash in building construction is actually not. In fact, the Hoover Dam tunnel spillway repair, back in 1942, marks the first major use of coal fly ash. To date, fly ash has been used on a number of high-profile projects, and most recently, the Freedom Tower at the World Trade Center site.

And even though producing power with coal is unpopular from an environmental perspective, the U.S. Energy Information Administration still predicts that the U.S., China and India will account for 88% of the projected net increase in coal consumption between 2006 and 2030.

The upshot is an awful lot of fly ash to deal with—about 131 million tons per year in the U.S. alone.

With fly ash also accounting for 55% of coal combustion waste, the industry is looking toward increased recycling as a good solution.

As such, some market research groups, such as the Cleveland-based Freedonia Group, are predicting that concrete products with recycled content will have a large role to play in the projected increased demand for green building products.

In particular, the group’s recent report, “Green Building Materials” (, sees the demand for green building materials growing 13% annually to $71.1 billion in 2015, with concrete products made from recycled materials such as fly ash posting the largest projected value gains.

Similarly, data from the American Coal Ash Association shows general upward trending with the percentage of fly ash which is being recycled annually.


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