Environmental Bricks

Why it’s Breakthrough: The use of fly ash in concrete to make bricks is not new, but the use of 100% fly ash to make bricks without firing in a kiln is new. In a National Science Foundation (NSF) sponsored project, Dr. Henry Liu found an innovative way to render such 100% flyash bricks “freeze-thaw resistant”, as judged by ASTM standard C62. This finding is a major breakthrough, as it provided a practical way to make bricks long-lasting even in cold climate. The NSF sponsored study also proved that the fly ash brick does not pollute water, air and soil, and releases less radon gas than concrete does. The brick also adsorbs mercury from the air, thereby rendering the ambient air cleaner for people to breathe.


The Story: Prior to this breakthrough, bricks made with 100% fly ash could pass only about 8 cycles of freeze-thaw, far short of the 50 cycles required to meet the brick industry’s standard. It is only through Dr. Liu’s research sponsored by NSF that this problem was solved, making fly ash brick suitable for use as building materials. Without coming up with this solution, the brick could not be used in cold climate (i.e., in regions that freeze in winter.)

In 2004 Dr. Liu received his first NSF Small Business Innovation Research (SBIR) Phase 1 grant aimed at solving the freeze-thaw problem of the fly ash brick. The mission was accomplished in 12 months, which enabled him to win a larger Phase II grant from NSF to develop the fly ash brick technology for commercial use. In 2008, through extensive R&D of this project, the fly ash brick technology became ready for commercial use. Ten nations, including the United States, have been licensed to use this technology. The U.S. licensee is CalStar Cement, a company located in California’s Silicon Valley. All the licensees are actively preparing to build the first fly ash brick factory in their respective countries within the next 24 months.

Being able to turn fly ash into building bricks is critical to our planet’s health. At present, in the United States alone, approximately 46 million tons of fly ash is land filled or stored in disposal ponds or mine pits, often causing groundwater pollution and creating eyesores. Only about 35% of the nation’s fly ash is recovered, most of which goes into concrete and roadbeds. This new Greenest Brick technology will significantly increase the fly ash recovery rate.

A major advantage of the Greenest Brick is that it eliminates the need for the high-temperature kilns required for clay brick production. No fossil fuel is burned to manufacture the 100% fly ash brick, nor is there any air pollution or carbon dioxide emitted thereby contributing to global warming. The compaction process used to make fly ash bricks is not only free of the usual carbons that go into firing clay bricks, but is also 10 times more energy-efficient than conventional bricks.

Many researchers in the past were concerned that fly ash products may emit mercury vapor into air, which in turn may be hazardous to health. Through a sophisticated test, the NSF project found that fly ash bricks not only emit zero mercury, they actually adsorb mercury from the ambient air, making the ambient air cleaner for people to breathe. This was pointed out in an article entitled, “Follow the Green Brick Road,” on the NSF Website, and recited as Case Study 17 in the EPA website on C2P2.