April 3, 2024: A team of scientists at the Indian Institute of Science (IISc) in Bangalore have created a new material that could replace natural sand in construction. Natural sand, widely used in construction, is becoming a scarce resource, thus creating the need for alternative and sustainable building materials.
The team at IISc’s Centre for Sustainable Technologies (CST) is exploring ways to utilise carbon dioxide (CO2) captured from industrial waste gases. They will treat excavated soil and construction waste with the CO2 produced, which can become an alternative to natural sand.
These materials can then be used to partially replace natural sand. 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 press release as cited in media reports.
The research at IISc, led by Assistant Professor Souradeep Gupta, showed that using CO2-treated construction waste in mortar, followed by curing in a CO2-rich environment, can speed up the development of the material’s strength.
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, Dr Souradeep Gupta said.
This process is expected to bring a 20-22% increase in the material’s compressive strength. Further, injecting CO2 into clay soil, commonly found at construction sites, improves its interaction with cement and lime. This stabilises the clay while enhancing its overall engineering performance.
In another study, Dr Gupta’s team has explored incorporating captured CO2 into excavated soil to develop cement-lime-soil composites, replacing up to half of the fine aggregates in mortar. This process facilitates the formation of calcium carbonate crystals, resulting in improved strength and reduced pore space. Exposing these materials to CO2 further accelerates curing and increases early-age strength by 30%.
Researchers develop 3D-printable materials
Further, the researchers have developed 3D-printable materials using stabilised excavated soil combined with binders such as cement, slag and fly ash. These materials provide superior printability, which could reduce the dependence on cement and sand by up to 50% each.
Future research will focus on the impact of industrial flue gas on these materials’ properties, which could result in industrial applications and revising standards for cement-based construction materials.
Click to read about manufactured sand and its growing importance in the construction industry
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