Researchers from National University of Singapore (NUS) Design and Environment have discovered that incorporating a small amount of dry biochar powder recycled from saw dust into concrete mixture can make concrete structures up to 20 per cent stronger and 50 per cent more impermeable to water. Biochar-a carbon-rich material that absorbs and retains water well is generated from biomass and frequently used in the agricultural industry as soil amendment to improve crop yield. Now the same material could also be used to make buildings stronger. The strategy makes use of the biochar’s porous and fibrous structure and its good water absorption and retention properties to enhance the concrete’s curing and hardening process, and subsequently improve the strength and permeability properties of concrete structures.
Associate Professor Kua Harn Wei, his PhD student, Mr Souradeep Gupta, and their team from the Department of Building at NUS School of Design and Environment further expanded the application of biochar by successfully using biochar recycled from saw dust to significantly improve the mechanical and permeability properties of concrete and mortar.
The novel method also promotes wood waste recycling. The use of biochar technology in concrete construction therefore offers an innovative approach to store large amounts of carbon in buildings while enhancing the building structures. Using this method, close to 50kg of wood waste can be utilised for each tonne of concrete fabricated. This translates to around six tonnes of wood waste recycled for every home unit with a 100sqm floor area.
In the experiments, the researchers found that improvement in early strength and impermeability of the concrete and mortar mixture can reach up to 20% and 50% respectively. This can facilitate early removal of formwork, which substantially saves construction time and cost. Furthermore, biochar itself locks in carbon in its structure, which would otherwise be released to the atmosphere by decay or by incineration of biomass. The use of the biochar technology in concrete construction is therefore a novel and innovative way to store carbon in buildings while promoting recycling of wood waste and strengthening building structures.
The NUS team is currently in discussion with a local firm to explore the commercialisation of this technology, and is also leveraging this technology to develop other high performance cement composites with a wide range of applications.
(source: NUS Press Release)