Materials

Recycled wood waste makes concrete stronger and more watertight

Recycled wood waste makes conc...
On the left is the enhanced concrete, and on the right is a sample of biochar generated from wood waste that was used to make it 
On the left is the enhanced concrete, and on the right is a sample of biochar generated from wood waste that was used to make it 
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A NUS infographic illustrating how the new method could be used
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A NUS infographic illustrating how the new method could be used
On the left is the enhanced concrete, and on the right is a sample of biochar generated from wood waste that was used to make it 
2/2
On the left is the enhanced concrete, and on the right is a sample of biochar generated from wood waste that was used to make it 

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)."

A NUS infographic illustrating how the new method could be used
A NUS infographic illustrating how the new method could be used

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

5 comments
Paulinator
Is the biochar produced thru anaerobic combustion? If so...well...
piperTom
It's both more and less. The carbon in the wood waste was extracted from the air by trees. Thus, capturing that carbon transforms a carbon neutral transaction into a net negative. Don't cheer yet: if you make concrete better and more useful, then people will use more concrete. Cement manufacture is a huge producer of CO2. That effect is likely to blow away any gains made in manufacture.
Expanded Viewpoint
They could use some of the wood waste to heat an anaerobic chamber like what they do to make coke for steel furnaces, except not run it to full cycle if pure Carbon is not desired. They don't say how much of the bio material is driven off of the wood waste. By burning some of the wood waste, they would save on the cost of electricity or natural gas for the process of making the biochar. They could also put the wood waste into a compost stream for gardens and farms. Randy
DaveWesely
Biochar is produced by heating the cellulose in an oxygen free environment. It isn't burned.
Nik
The concrete would need to be 'slump tested' to ensure that it reaches the required compression strength/volume. I'd like to see figures for that before a high-rise building was constructed from it. Any way that waste material can be made useful, cant be bad. As for anthropogenic global warming claims, most people with their brain functioning know that they are mythical.