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Research finds concrete use for recycled glass


A 3D-printed concrete has been developed by researchers from RMIT University in Melbourne, using recycled glass to replace traditional aggregates.

As sand becomes a more precious commodity, more and more advancements in sustainable concrete processes have become apparent, with this latest attempt recognising the similar properties between recycled glass and sand.

In a paper for Construction and Building Materials, to be published in early 2022, the research team focused on the correlation between mechanical properties and microstructures within the concrete.

“This study investigated the flexural properties of 3D-printed concrete with 50 per cent sand replaced by different gradations of recycled glass through three-point bending tests,” the report abstract read.

The study used several concrete mixtures composed of varying degrees of glass and put each of them through three-point bending tests.

As the products bent under various weights, the team used X-ray micro-computed tomography and scanning electron microscopy to understand the effects that stress had on the structure of the 3D-printed concrete.

“Experiment results showed the reference mixture without glass exhibited brittle fracture, in contrast to those with glass showing strain softening in the post-peak region,” the abstract continued.

And while the occurrence of some cracks was linked with the addition of glass in some mixtures, the glass particles in others increased flexular strength by 25 to 33 per cent.

Interestingly, the strength of the concrete beams also depended on the direction the mixture was printed – either along the length of the beam or perpendicular to its direction.

Overall, it could be said by the RMIT team that the use of glass particles had its use in improving the usefulness of 3D-printed concrete.

“Based on µCT and SEM analysis, the strength improvement and crack development in this condition was primarily related to the glass particles located alongside the crack path,” the abstract concluded.

Purchase the full report here.

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