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Knitting a sustainable future for concrete construction

Knitting a sustainable future for concrete construction

Researchers are unravelling the potential of knitted wool as a sustainable alternative to conventional metal, timber and fibreglass formwork used in building concrete columns.

This innovative construction technique could be a game-changer, especially in an industry responsible for a staggering 11 per cent of global carbon emissions.

Unlike regular formwork, which is often discarded after a single use, wool formwork boasts impressive eco-credentials. Not only can it be reused up to three times, it’s also biodegradable.

Head of the Abedian School of Architecture at Bond University, Professor Paul Loh, teamed up with fellow architect David Leggett of LLDS architects and textile design expert Dr Jenny Underwood of RMIT University to bring this concept to life.

Using Australian wool, which weighs less than one per cent of traditional formwork, an advanced knitting machine produced seamless, sock-like forms. These wool forms were then suspended by an industrial robotic arm while concrete was poured in, creating test columns as high as 1.8 metres and 17.5 centimetres wide.

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Professor Loh said fabric formwork had been used since the 19th century but was limited by the unpredictable shapes produced during casting. “Typically, woven fabric is used which is also restrictive in its shape and requires tailoring skills,” he said.

“The use of 3D-knitted fabric has never been explored to its full capacity in this application, and the research sets out to explore the feasibility of casting using bio-material such as wool and testing the repeatability of the cast using a single mould.”

Professor Loh highlighted that for these columns to be viable for use in the construction industry, they need to be scaled up to twice their current height and width while maintaining a uniform shape.

“While the fabric naturally produces a different and almost novel aesthetic in the cast, the research aims to find the correlation between the knit architecture and the resulting cast geometry,” he said. “Our research has so far only produced a feasibility study, and our next step is to delve deeper into the computational code behind the 3D-knit fabric to align it with the shape and structural performance.”

The wool forms are washed in cold water between uses. Another notable advantage is the potential to use recycled wool from garments that might otherwise have gone to landfill.

Professor Loh said that the construction industry contributes an estimated one-third of the world’s waste, with the majority ending up in landfills. “More so than ever, we need to re-examine our construction practices against the three principles of circular design: eliminate construction waste, circulate products for long-term use and regenerate natural systems by using biodegradable material,” he said.

This research builds upon Professor Loh’s investigations into variable-shaped formwork, a field he has been exploring since 2016. His earlier discoveries helped inspire the establishment of Curvecrete, a company that uses robotic forming technology to mould low-carbon concrete into curved shapes.

The University of Melbourne provided the funding for this latest phase of research.

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