IISc Researchers Develop Material With Potential To Replace Sand In Construction

Bengaluru: In what could be a major breakthrough, researchers at Indian Institute of Science (IISc) here have developed a material that could replace natural sand in construction.

With natural sand getting scarce, finding alternatives is crucial.

Working towards that goal, researchers at IISc’s Centre for Sustainable Technologies (CST) have been looking at ways to store carbon dioxide from industrial flue gas in excavated soil and construction waste, India Today reported.

That can then be used to partially replace natural sand, the researchers have claimed.

“This would not only reduce the environmental impact of construction materials but also impart properties that can enhance their use for construction,” IISc said in a statement.

The team, led by CST assistant professor Souradeep Gupta, has shown that replacing natural sand with carbon dioxide-treated construction waste in mortar and then curing it in a controlled, CO2-rich environment can speed up the development of the material’s engineering properties.

“CO2 utilisation and sequestration can be a scalable and feasible technology for manufacturing low-carbon prefabricated building products while being aligned with the nation’s decarbonisation targets,” explained Souradeep.

The process being followed aims to enhance the materials’ compressive strength by 20-22%.

The effect of injecting carbon dioxide gas into clayey soil, typically excavated from construction sites, has been tested.

It resulted in better stabilisation of clay by cement and lime, and reduced surface area, pore volume and lime reactivity of clay in soil, consequently improving the material’s bulk engineering performance.

Souradeep’s team explored effects of sequestering carbon dioxide in excavated soil to create cement-lime-soil materials, replacing up to 25% and 50% of fine aggregates in mortar.

The process results in formation of calcium carbonate crystals, reducing medium capillary pores and enhancing compressive strength. Exposing these blocks to carbon dioxide led to early-age strength by 30% and accelerated curing time.

3D-printable materials using excavated soil stabilised with binders like Portland cement, blast furnace slag and fly ash were also developed. These demonstrate superior extrusion and buildability, potentially reducing cement and sand requirements by 30% and 50%, respectively.

Further research will assess impact of industrial flue gas on these materials’ properties, before it is planned for industrial application and standards revision in cement-based construction materials.