Biochar derived from wood waste could make concrete buildings 20 per cent stronger and 50 per cent more impermeable to water, according to new research out of the National University of Singapore.
The research found that adding a small amount of biochar made from sawdust improved both strength and permeability properties of concrete, thanks to biochar’s porous and fibrous structure and water absorption and retention properties, which enhance the curing and hardening process.
Associate professor Kua Harn Wei from NUS School of Design and Environment said the strategy dealt with both wood waste and building quality issues.
“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,” he said.
“At the same time, we are putting the large amount of wood waste generated in Singapore to good use.”
The country in 2016 produced 530,000 tonnes of wood waste, much of which went to landfill.
The researchers also found that the increased strength could enable early removal of formwork, which translated into construction time and cost savings.
Associate professor Kua said using biochar in concrete meant that the carbon emissions were locked in the material, which would otherwise be lost to the atmosphere through incineration or decay.
“Close to 50 kilograms of wood waste can be utilised for every tonne of concrete fabricated,” he said.
“We typically require 0.5 cubic metres 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 typical four-room [Housing and Development Board] unit with a floor area of 100 square metres.”
The research team is currently in discussion with a local company to explore commercialisation paths, and is also working on other high-performance concrete composites.