IISc. team explores new ways for sustainable construction
In order to address the issues of dwindling resources of natural sand and the increase in carbon dioxide emissions, especially from manufacturing cement or fired clay bricks, researchers at the Indian Institute of Science (IISc.) are exploring ways to store carbon dioxide from industrial flue gas in excavated soil and construction and demolition (C&D) waste.
According to the IISc., the construction sector today faces several challenges.
It said that natural sand is fast becoming a scarce resource and that it might run out of supply by 2050.
Carbon dioxide emissions, especially from manufacturing cement or fired clay bricks, are increasing every year.
The amount of C&D waste is on the rise – about 150 million tonnes are generated annually in India and the recycling rate is only about 1%.
To address such challenges, researchers at the IISc.’s Centre for Sustainable Technologies (CST) are exploring ways to store carbon dioxide from industrial flue gas in excavated soil and C&D waste.
“CO2 utilisation and sequestration can be a scalable and feasible technology for manufacturing lowcarbon prefabricated building products, while being aligned with the nation’s decarbonisation targets,” said Souradeep Gupta, Assistant Professor at CST.
Mr. Gupta’s team has shown that replacing natural sand with carbon dioxidetreated C&D waste in mortar and then curing it in a controlled, CO2rich environment can speed up the development of the material’s engineering properties, and enhance its compressive strength by 2022%.
His lab has also tested the effect of injecting carbon dioxide gas into clayey soil – typically excavated from construction sites. This resulted in better stabilisation of clay by cement and lime, and reduced the surface area, pore volume, and lime reactivity of clay in soil, thereby improving the bulk engineering performance of the material.
The team has also developed 3Dprintable materials made of excavated soil stabilised with a combination of binders like Portland cement, blast furnace slag (a granular calciumsilicate byproduct), and fly ash.