House Proud

Clay bricks are quite literally the building blocks of Indian civilisation. The ancient cities of Mohenjo-daro, Harappa, and Dholavira were entirely made of them. While almost everything else from the Indus Valley age has been forgotten, the art of brick-making has remained, and today, India is the second-largest producer of clay bricks, feeding 10% of global demand.

The downside is that it’s one of the country’s most polluting industries. The kilns used to fire the bricks burn coal, consuming the most amount of the fuel after the power and steel industries. according to a report by Delhi-based energy efficiency consultants Greentech Knowledge Solutions. Efforts made to reduce consumption of coal with new kiln designs have cut coal use by up to 5 million tonnes a year. But that’s too little when you consider that the industry uses more than 25 million tonnes a year. Again, 4,000 tonnes of soil is excavated every year to produce 1 million bricks, affecting around 500 sq. km of farmland.

With the country imposing stricter emission and pollution control norms, brickmakers have been looking for cleaner options. One solution was brought to India in 1992 by industrialist Lalit Mohan Thapar. When in Munich on business, he came across a new kind of brick called Ytong or blue cement. It was lighter than the traditional clay brick, much stronger, needed very little mortar, was fire resistant, and provided insulation.

Thapar was so impressed, he bought the technology from Ytong Gmbh, a German company. The trade name for Ytong is AAC (autoclaved aerated concrete). However, Thapar found that the mix suggested by Ytong did not work well in Indian conditions, so he put his own chemical engineers on the job. (The Thapar Group, which he headed, included a paper factory which employed chemical engineers.) The engineers used the existing formula of sand, lime, cement, aluminium powder, and water to come up with a combination that suited the Indian climate better. They also found that sand could be replaced with fly-ash, a residue in thermal power plants, and long seen as a pollutant.

By using fly-ash in AAC bricks, Thapar was able to solve two problems at once: the reliance on coal came down (the kilns used to fire AAC bricks can use fuel such as rice husk, an ecofriendly alternative); and the polluting fly-ash was used constructively. The problem was that buyers were wary of these lightweight, grey bricks. For 10 years, Thapar’s AAC venture, Biltech, struggled to find buyers.

But now that green buildings are finally catching on, AAC bricks are suddenly in demand. With developers such as DLF and large EPC (engineering, procurement, and construction) contractors such as L&T and GMR becoming aware of their benefits, AAC bricks have gained acceptance. They have been used to build the Westin Pune; Lavasa township near Pune; Lokhandwala Complex, Oberoi Springs, InOrbit Mall, and Imperial Towers in Mumbai; and Indira Gandhi International Airport, and the Commonwealth Games Village in Delhi.

As more developers look to earn green credits, the demand for AAC bricks is expected to go up.