A team of researchers from the National University of Singapore (NUS) has developed a novel new method to recycle wood waste by incorporating it into cement and mortar mixtures, making the resulting materials both stronger and more watertight.

In just one year, furniture factories in Singapore can produce over half a million tonnes of wood waste. This waste primarily takes the form of sawdust, and a positive way to recycle this waste is to turn it into biochar, a charcoal-like substance.

Biochar has a variety of environmental benefits. While most biomass breaks down within 10 or 20 years, releasing its carbon into the atmosphere, biochar is an incredibly stable material and able to hold its carbon for thousands of years.

A 2010 study found that increasing the global production of biochar could offset over 10 percent of the world's human-caused greenhouse gas emissions. Due to its strong water absorption and retention capacity, biochar also is known to be a wonderful soil enricher.

In exploring other commercial applications for biochar, the team at NUS discovered that adding a small amount of it to cement or mortar mixtures made the resulting materials up to 20 percent stronger and 50 percent more watertight.

"Close to 50 kilograms (110 lb) of wood waste can be utilized for every tonne of concrete fabricated," explains Kua Harn Wei, a researcher on the project. "We typically require 0.5 cubic meter of concrete for every square meter of floor area (17.6 cu ft per 10.7 sq ft) built in Singapore. This translates to around six tonnes of wood waste being recycled to build a typical four-room HDB unit with a floor area of 100 square meters (1,076 sq ft)."

As well as improving the strength of concrete structures, and recycling wood waste that would otherwise be incinerated or put in a landfill, the method is a unique way of storing carbon in buildings. Incorporating biochar into concrete construction allows the carbon to be locked into a structure instead of being released into our atmosphere either through incineration or decay.

Source: National University of Singapore

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