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20 October 2026
Swiss researcher combines bacteria with robotic printing to make cement-free concrete
20 October 2026
The bacteria bonds sand and aggregate together into a solid material by forming calcium carbonate, all without heat.
A Swiss researcher has developed a printable concrete-like material that is bound together by bacteria rather than cement.
Karen Antorveza Paez developed the process while completing her doctorate at the Department of Architecture at ETH Zurich and has used it to make a number of architectural elements. More research is needed to make the material load-bearing.
The bacteria, Sporosarcina pasteurii, bonds sand and other grains together into a solid material by forming calcium carbonate, the mineral that makes up limestone. No heating is required, which raises the possibility of avoiding the emissions produced in making cement at some point in the future.
The process known as biocementation has previously been used to stabilise soils and in self-healing concrete.
When bacteria are combined with sand or other solid grains, they join the particles together into a solid structure made of interlocking, microscopic calcite crystals.
“We’re using bacteria to produce a sort of mineral glue”, said Antorveza Paez.
Fully digital manufacturing
She developed two different manufacturing methods. One, for architectural purposes, is robotic spraying.
In this technique, a robotic arm applies bacteria, the mineralisation substances for limestone formation and sand to a surface repeatedly and one after the other, building it up in height layer by layer.
This process is inspired by stromatolites, layered sedimentary rock formations that occur in nature when microorganisms deposit minerals over long periods of time.
At the 2025 Biennale Architettura in Venice, the process was left running uninterrupted for six months, letting visitors see the results for themselves.
“We have proven that the entire process of biocementation can be automated,” Antorveza Paez said.
Like baking a cake
For the other method, the team developed a “bio-ink” made of a gel based on water and naturally-occurring alginate and xanthan, as well as sand and live bacteria. The gel is printed to the desired form and then immersed in a bath containing urea and calcium chloride.
This is where the bacteria start their work by breaking down the urea with an enzyme called urease. The reaction releases carbonate ions and, as a by-product, ammonium. The carbonate and calcium chloride in the solution bond together to form calcium carbonate, also known as limestone, the same mineral that makes up seashells.
Microscopic crystals form between the grains of sand and interlock with each other.
The entire process takes two to five days, depending on the desired strength of the architectural component.
It involves providing a fresh mineralisation bath every day. The object is then left to dry, deactivating the bacteria and leaving a solid structure.
“It’s a bit like baking a cake. You’ve got the dough, which is still very malleable and delicate. Only the oven can turn it into something solid,” Antorveza Paez said, noting that the bacteria play the role of the oven.
This process has been used to create a facade element, among other things. It can be used to to build shade structures or partition walls.
“I’m fascinated by the fact that nature has found ways of manufacturing very sophisticated materials and that we can make these applicable to the problems we face today,” she said, adding: “The big question is no longer whether biocement works, but rather how well its properties can be managed.”
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