Researchers develop bio-bricks from agricultural waste

This mixture is poured into moulds and rammed with a wooden block to make a compact brick. (DH Photo)

Researchers from Indian Institute of Technology here and KIIT School of Architecture, Bhubaneshwar, have developed bio-bricks, from agricultural waste products. Their development serves the dual purposes of waste management and the development of eco-friendly, sustainable building materials.

This research was undertaken by Priyabrata Rautray, IIT and Avik Roy, of KIIT School of Architecture, Bhubaneshwar. The results of this research work, have been presented at the International Conference on Engineering Design (ICED2019) at TU Delft, Netherlands. The team’s bio-brick received a Special Recognition Trophy for sustainable housing at Rural Innovators Start-Up Conclave 2019 organised recently by National Institute of Rural Development and Panchayati Raj (NIRDPR) here.

“22 per cent of India’s total annual CO2 emissions is by the construction sector. Clay bricks, for example, not only use up fertile topsoil, but their manufacturing process also emits significant amounts of carbon dioxide into the atmosphere,” Rautray, said. More than 500 million tons of agricultural waste are produced in the country every year. While some of this is reused as fodder, 84 to 141 million-tons are burnt, which results in severe air pollution.

The Process

The process of making bio-bricks starts with careful selection of the dry agro-waste like paddy straws, wheat straws, sugarcane bagasse and cotton plant. The team decided to use dry sugarcane bagasse for the first sample. The bagasse is first chopped to the desired size. A lime-based slurry is prepared, and the chopped agro-waste is added to the slurry and mixed thoroughly by hand or mechanical mixer, to create a homogenous mixture.

This mixture is poured into moulds and rammed with a wooden block to make a compact brick. These moulds are left to dry for a day or two, after which the sides of the moulds are removed, and the brick is allowed to dry for fifteen to twenty days. It takes approximately a month’s time for these bio-bricks to attain its working strength by air drying.

Low-Cost housing

As these bio-bricks are not as strong as burnt clay bricks and cannot be used directly to build load-bearing structures, they can be used in low-cost housing with a combination of wooden or metal structural framework. Besides, these bricks provide good insulation to heat and sound and help in maintaining the humidity of the buildings, making these houses suitable for a hot-humid climate like India.

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