Dikhyaa Mohanty 
Researchers at the Indian Institute of Science (IISc) in this city have created a substance that could take the place of natural sand in construction, which could be a significant breakthrough. Alternatives must be found because natural sand is becoming harder to come by. In pursuit of that objective, scientists at the Centre for Sustainable Technologies (CST) at IISc have been investigating methods for sequestering carbon dioxide from industrial flue gas in dug-out soil and building debris, as reported by India Today. The researchers have asserted that this can then be utilized to partially substitute natural sand.
IISc stated in a statement that “this would not only impart properties that can enhance their use for construction but also reduce the environmental impact of construction materials.” The group, under the direction of CST assistant professor Souradeep Gupta, has demonstrated that the development of the material’s engineering qualities may be accelerated by substituting carbon dioxide-treated construction waste for natural sand in mortar and curing it in a controlled, CO2-rich environment.
In line with the country’s decarbonization goals, “CO2 utilisation and sequestration can be a scalable and feasible technology for manufacturing low-carbon prefabricated building products,” according to Souradeep. By using this procedure, the materials’ compressive strength should be increased by 20–22%. It has been investigated what happens when carbon dioxide gas is injected into clayey soil that is commonly dug from building sites. As a result, clay was more stabilized by cement and lime, and its bulk engineering performance was enhanced by decreased surface area, pore volume, and lime reactivity of clay in soil.
Souradeep’s group investigated the effects of storing carbon dioxide in soil that had been excavated in order to produce cement-lime-soil composites that could replace between 25% and 50% of the fine particles in mortar. Calcium carbonate crystals are formed as a result of the process, which decreases medium capillary pores and increases compressive strength. These blocks’ early-age strength increased by 30% and the curing period was sped up by exposing them to carbon dioxide. Additionally, 3D-printable materials stabilized with binders such as Portland cement, blast furnace slag, and fly ash were produced utilizing excavated soil. These exhibit excellent extrusion and buildability, which could result in a 30% and 50% reduction in the amount of cement and sand needed, 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.
