'Green' Bricks Proven To Be Greener Than Thought

Researchers have found that bricks made from fly ash--fine ash particles captured as waste by coal-fired power plants--may be even safer than predicted. Instead of leaching minute amounts of mercury as some researchers had predicted, the bricks apparently do the reverse, pulling minute amounts of the toxic metal out of ambient air.

Each year, roughly 25 million tons of fly ash from coal-fired power plants are recycled, generally as additives in building materials such as concrete, but 45 million tons go to waste. Fly ash bricks both find a use for some of that waste and counter the environmental impact from the manufacture of standard bricks.

"Manufacturing clay brick requires kilns fired to high temperatures," said Henry Liu, a longtime National Science Foundation (NSF) awardee and the president of Freight Pipeline Company (FPC), which developed the bricks. "That wastes energy, pollutes air and generates greenhouse gases that contribute to global warming. In contrast, fly ash bricks are manufactured at room temperature. They conserve energy, cost less to manufacture, and don't contribute to air pollution or global warming."

Once colored and shaped, the FPC bricks are similar to their clay counterparts, both in appearance and in meeting or exceeding construction-material standards.


SOURCE:
PhysOrg.com

Fly ash is a fine, glass-like powder recovered from gases created by coal-fired electric power generation. U.S. power plants produce millions of tons of fly ash annually, which is usually dumped in landfills. Fly ash is an inexpensive replacement for Portland cement used in concrete, while it actually improves strength, segregation, and ease of pumping of the concrete. Fly ash is also used as an ingredient in brick, block, paving, and structural fills. Link