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Replacing sand with glass waste in concrete 3D printing

Researchers from NTU Singapore developed a method to use recycled glass in concrete 3D printing, for a more environmentally sustainable way of building and construction.

According to data by the National Environment Agency, only 13 per cent of the 74,000 tonnes of glass waste generated in Singapore was recycled in 2021. At the same time, due to growing populations, urbanisation and infrastructure development, the world is facing a shortage of sand, with climate scientists calling it one of the greatest sustainability challenges of the 21st century.

Glass is made of silica, a major component of sand – since glass is made from sand – but also a dwindling resource. Sand is also used in concrete.

The NTU researchers developed a special concrete mix with added recycled glass particles in different sizes. According to lab tests, the concrete has excellent mechanical strength and buildability. Using this mix, they 3D printed a concrete bench. The researchers noted that the concrete didn’t deform or collapse before it cured, and it was fluid enough to flow easily through the printer nozzle.

The researchers plan to work with partners to optimize the technology to 3D print large scale structures.

Photo: NTU Singapore