Some of the earliest houses in Northern Europe were made out of slabs of peat, as it was a cheap and abundant building material. Now, Estonian scientists are revisiting the idea of peat houses, only this time they’re looking at 3D-printing the things.

Peat is plentiful in Estonia, as it’s found in the wetlands that cover approximately 22 percent of the landscape. Another thing that Estonia has a lot of is oil shale ash – the country produces an estimated 7 million tonnes (7.7 million tons) of the waste substance annually, only 5 percent of which gets repurposed.

To that end, researchers from the University of Tartu and the Estonian University of Life Sciences have created a 3D-printable concrete-like material made mainly from milled peat, with oil shale ash serving as a binder. Silica nanoparticles are also added to the mix.

In past efforts to create peat-based building materials, the chemical qualities of peat have prevented binders from hardening. Thanks to oil shale ash’s very high pH value, however, that isn’t a problem this time around.

The resulting material hardens within one day of being printed, although it still retains an elastic quality for some time after – this means that blocks of it can be stacked snugly together, without any gaps between them that would allow wind to pass through. It’s also said to be strong, light, durable and incombustible (despite the fact that peat is commonly burned as fuel), plus it exhibits a low rate of heat transfer, and is good at blocking sound.

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