¿ìè¶ÌÊÓƵs have created an exceptionally strong, lightweight material out of microwaved bamboo that could be used to construct the next generation of skyscrapers, cars and aeroplanes.
At the moment, steel, concrete and bricks are the most commonly used construction materials, but they are non-renewable and their production contributes substantially to global greenhouse gas emissions.
Bamboo, in contrast, is a fast-growing, renewable material that is already used in houses and scaffolding in many Asian countries. However, it is not strong enough in its natural form to construct tall buildings.
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To make bamboo stronger, Liangbing Hu at the University of Maryland in the US and his colleagues treated it with chemicals to partially remove a substance called lignin, then microwaved it to remove water. This caused the bamboo to shrink by about a third of its size and its cellulose fibres to pack together in dense layers.
The tightly-packed cellulose layers were able to form strong chemical bonds called hydrogen bonds that enhanced the strength of the bamboo while still maintaining its lightness, says Hu.
The tensile strength of the microwaved bamboo – or the amount of stretch it could withstand without breaking – was 6 times that of steel when compared by weight. It could also withstand slightly more compression than concrete and bricks and did not degrade when left outdoors.
These properties make the material suitable for constructing skyscrapers that would be lightweight but stay stable by being strongly bolted to the ground, says Hu. It could also potentially be used to make lighter electric cars that could make up the weight with bigger batteries for travelling further, or lighter aeroplanes that require less fuel to propel them, he says.
Hu’s team and other research groups have also used wood to make super-strong, renewable building materials, but bamboo has the advantage of growing faster, meaning it can be produced on a larger scale, he says.
Hu and his colleagues are now planning several engineering projects to test the potential of their microwaved bamboo in real-life building contexts.
ACS Nano
