For centuries the red clay brick has been, quite literally, the building-block of India. Simple, cheap, and locally available, these bricks are ubiquitous across the country, and continue to be manufactured by the billions using techniques largely unchanged since the time of the British Raj.
However, as India’s population booms, the traditional kiln-fired brick is being produced on a scale never seen before, and the boom is having unexpected consequences. A number of environmental drawbacks have arisen, such as topsoil depletion from the harvesting of clay and greenhouse gas emissions due to the massive energy demands of the kilns. Once taken for granted as the nation’s primary building material, many manufacturers and policymakers are now wondering whether the red clay brick can continue to serve rising demand.
At the same time, a seemingly unrelated problem is plaguing Indian industry: the country’s 800 paper mills are burning cheap raw materials to generate energy, and together they can produce as much as 80,000 tons of waste ash every day. Much of this ash is unusable and sent to landfills, occupying valuable farmland at great expense to paper mill owners.
A team at MIT, including Tata Fellow Michael Laracy and Postdoctoral Associate Thomas Poinot, looked at these problems and spotted an opportunity to solve both at once: Using industrial ash to develop an alternative building materialto the red clay brick.
The result of their research is the eco-BLAC brick, a low-cost, environmentally-friendly masonry unit. Formulated using industrial ash, the brick employs “alkali-activation technology, a low-energy process,” according to Laracy. While traditional bricks must be kiln-fired at 1000°C, consuming huge amounts of fuel, the eco-BLAC brick can be cured at ambient temperatures, massively reducing energy requirements. “We don’t need any firing or source of energy to cure the bricks,” says Poinot. Simultaneously, ash waste is being recycled, alleviating the burden of landfilling.
One of Muzaffarnagar’s more than 200 “bull ring” kilns, where red clay bricks are fired.
Using ash from paper mills in Muzaffarnagar and a formula of locally-sourced chemicals and minerals, Laracy and Poinot have been able to produce hundreds of high quality samples, gaining the attention of industrialists in Uttar Pradesh, India’s most populous state, and even making an appearance on the local TV news.
“I am very hopeful for this project,” says Pankaj Aggarwal, chairman of the Paper Manufacturer’s Association of Uttar Pradesh. “These bricks are more even, cheaper in price, and the best thing is, we are using our waste that is being dumped right now.”
The MIT team, which also includes faculty members Charles Fine, Elsa Olivetti, John Ochsendorf, and Hamlin Jennings, has “the whole span of skills we need to be good at this project,” according to Poinot. For the last two years they have used the city of Muzaffarnagar, Uttar Pradesh, as a home base in India. Muzaffarnagar is home to more than 200 of the old-fashioned “bull ring” brick kilns, and to thousands of acres of land given over to ash landfills. It has proven to be a fertile testing ground for approaching this nationwide problem.
“The best thing about Muzaffarnagar is the friendliness of the people,” says Laracy. “Despite the language barrier, people want to help in any way they can.”
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