Wood waste could become the building material of the future, creating stronger, more watertight homes with a lighter footprint on our environment. Researchers from the National University of Singapore have come up with an innovative way to turn biochar from sawdust into cement, as an alternative use for the large volume of wood waste being produced. Wood waste from furniture factories makes up a large part of the waste generated in Singapore. 2016 alone saw more than 530,000 tonnes of wood waste produced, much of which was in the form of sawdust.
Now, instead of being incinerated or going to landfill, wood waste can be recycled to make biochar, a porous, carbon-rich material that absorbs and retains water. When a small amount of dry biochar powder is added into concrete or mortar, it enhances the curing and hardening of the mixture.
In their experiments, the researchers found that the strength and impermeability of the concrete and mortar mixture can reach up to 20 and 50 per cent respectively. This can facilitate early removal of formwork, which substantially saves construction time and cost. What’s more, biochar ‘locks in’ carbon in its structure, which would otherwise be released to the atmosphere by decay or by incineration of biomass. Associate professor Kua Harn Wei said that 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”, he added. “This translates to around six tonnes of wood waste being recycled to build a residential apartment with a floor area of 100 square metres.”