This house is made from recycled diapers mixed into concrete

Used diapers could be a source of building materials, as they can be recycled to replace the sand normally used in concrete.

Diapers are an unlikely building material, but they work
Anjar Primasetra

Concrete made from recycled diapers instead of sand could be used to build houses, after a proof-of-principle experiment has shown that the resulting material is surprisingly sturdy.

Sand is crucial for many building materials, from concrete to plaster to glass, but demand is set to skyrocket over the coming decades and it is unclear how much sand might be left to extract, which could make it an increasingly expensive resource.

Now, Siswanti Zuraida at the University of Kitakyushu in Japan and her colleagues have developed a concrete material that uses cleaned and shredded diapers as a sand replacement.

Zuraida, who is originally from Indonesia, saw an opportunity to reuse diapers. “We have the fourth largest population in the world – every day babies are born and how many diapers do we produce?”

To make the first prototype, Zuraida reused diapers from her own young children. The team washed, sterilised and dried the diapers, before shredding and mixing them with different amounts of other materials, such as gravel or sand. This served as the aggregate that the team mixed with Portland cement and water to create concrete.

The researchers tested these different samples and found that, while the modified concrete had slightly less compressive strength than pure concrete, samples that were 8 per cent diapers could be used for structural features like supporting beams and columns, according to Indonesian building regulations. While not as strong, samples that were close to 40 per cent diapers could be used for non-load bearing features like walls and floors, according to the same regulations.

To test this, the team built the walls and floors of a 36-square-metre prototype house using the 40 per cent diaper concrete, with structural features made from regular, load-bearing concrete. This construction required around 1.7 square metres of diapers – equivalent to about 200 individual ones, says Zuraida. A young baby can use as many as five diapers per day, she says, meaning there is no shortage of raw material. The bottleneck on scaling this method up will be collecting the used diapers from households.

“It’s a great initiative, especially because there’s a shortage of sand,” says Juliana Calabria-Holley at the University of Bath, UK. Using the concrete to build a prototype house shows that the material can work in the real world, but it would be good to test its durability over longer time periods, she says.

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