But thanks to a team of researchers in National University of Singapore (NUS) who developed a method that recycles these tons of carbon-rich waste into an admixture for cement and concrete.
Biochar as a Carbon Sink
A form of charcoal, biochar is produced from agricultural waste or biomass via pyrolysis and stored in the soil both as a supplement and as a carbon sink. Biochar is highly water absorbent and as such, used as a soil enhancer.
Biochar is also considered as environment friendly due to its capability to reduce atmospheric carbon. Agricultural wastes degrade in a decade emitting carbon dioxide into the atmosphere, while biochar is a stable material that locks in carbon for thousands of years. According to a separate study, if the global production of biochar is increased, more than 10 percent of the greenhouse gas emissions worldwide can be offset.
Eco-friendly Cement Admixture
Researchers from NUS found out that when biochar generated from wood wastes is incorporated to cement and concrete as an admixture, it improves the cement’s strength by 20 percent. With biochar, the cement is also 50 percent more watertight. Only a few amount of the biochar powder is required to effect such enhancements.
This improvement in water impermeability means that a construction project can be finished earlier, saving time and cost. Not only will the biochar enhance the cement and concrete’s performance, but it will also act as a carbon sink. Recycling the biochar from wood waste also means saving space, material, and cost.
As Associate Professor Kua said, “This is a simple and affordable strategy to enhance our building structures, particularly in Singapore, where water leakage from rain and water pipes are common problems. At the same time, we are putting the large amount of wood waste generated in Singapore into good use. Close to 50 kilograms of wood waste can be utilised for every tonne of concrete fabricated. We typically require 0.5 cubic metre of concrete for every square metre of floor area built in Singapore. This translates to around six tonnes of wood waste being recycled to build a residential apartment with a floor area of 100 square metres.”