Alternative to sand prepared for eco-friendly construction

Scientists at the Indian Institute of Science (IISc), Bengaluru, have developed a material that can replace sand in construction. This development came as a response to the increasing shortage of sand, a vital ingredient in construction materials. A team at IISc's Center for Sustainable Technologies (CST) is exploring ways to utilize carbon dioxide (CO2) derived from industrial waste gases. They have treated excavated soil and construction waste with this CO2, turning it into a strong alternative to sand. This material can be used to partially replace sand, an IISc press release said. This will reduce the environmental impact of construction materials. Assistant Professor Dr. Research led by Saurdeep Gupta showed that using CO2-treated construction waste in mortar and curing it in a CO2-enriched atmosphere significantly increased the strength of the material.

These studies are being conducted through Dr. Jin's lab. Saurdeep Gupta said CO2 utilization and sequestration can be a scalable and viable technology for producing low-carbon precast building products while remaining in line with decarbonization goals. This innovative process increases the compressive strength of the material by 20 to 22%. Additionally, injecting CO2 into the soil, commonly found at construction sites, improves its interaction with cement and lime. It not only stabilizes the soil but also improves its overall engineering performance. Dr. Gupta's team has researched incorporating captured CO2 into excavated soil to create cement-lime-clay composites that replace half the fine aggregates typically used in mortar.

This technology promotes the formation of calcium carbonate crystals, thereby increasing the strength of the construction and reducing pore space. Exposing these materials to CO2 accelerates curing and increases initial strength by 30%. Researchers have also developed 3D-printable materials using excavated soil stabilized with binders such as cement, slag and fly ash. These materials reduce the need for cement and sand by up to 50%. Future research will focus on the effect of industrial flue gas on the properties of these materials, which may pave the way for future industrial use of these materials and may also lead to revised standards for cement-based construction materials.