India’s brick industry, spread out over 100,000 kilns and producing up to 2 billion bricks a year, is a big source of pollution. To fire to hot temperatures, the kilns use huge amounts of coal and diesel, and the residue is horrendous: thick particulate matter, poor working conditions, and lots of climate-changing emissions.
MIT students have created an alternative. The Eco BLAC brick requires no firing at all and makes use of waste boiler ash that otherwise clogs up landfills.
“Clay bricks are fired to 1,000 degrees Celsius,” says Michael Laracy, a graduate student who’s worked on the project. “They consume a tremendous amount of energy from coal and there’s also the issue that these bricks are made completely of topsoil, so they’re depleting the amount of farmable land [the Indians] have.”
The Eco BLAC brick is 70% boiler ash from paper mills mixed with sodium hydroxide, lime, and a small amount of clay. It cures at ambient temperature, relying on “alkali-activation technology” to give it strength. It was developed in by MIT’s Tata Center for Technology and Design and is part of a bigger project to develop low-cost, low-emission housing for India’s inner city slums.
Laracy, a structural engineer, says the brick is currently being tested in partnership with a paper mill in Muzaffarnagar, a city north east New Delhi. The product is cheaper than a conventional brick, but it still needs to prove its long-term durability. All being well, the team hopes to co-locate a brick plant within the paper mill, so the waste can be converted immediately.
If the Eco BLAC bricks prove successful, that would be good for India’s air quality as well as its food security. Using large amount of clay topsoil deprives farmers of arable land to grow crops.