Yeast and Gelatin Bind Sand Into Freeze-Dried Building Material for Mars

Civil engineers at the Hong Kong University of Science and Technology (HKUST) have developed a concrete-like material that binds sand with gelatin and genetically engineered yeast. The research, led by Jishen Qiu, targets construction on Mars, where producing cement or processing materials at high temperatures would be difficult. The results are published in the journal Chem Circularity.

A Biological Glue

The binder combines gelatin with yeast cells engineered to carry sticky surface proteins, modelled on the adhesive proteins of mussels. The gelatin holds the mixture together and feeds the cells, while the sand provides structural mass. The team tested eight yeast strains: one wild type and seven engineered variants. Fine sand served as a stand-in for Martian soil.

Curing by Freeze-Drying

The idea came from freeze-dried fruit, which hardens as it dries. On Mars, subzero temperatures and very low air pressure turn ice directly into vapour. The researchers reproduced this by freezing cast blocks and freeze-drying them for two days at about -55°C, at roughly one ten-thousandth of Earth’s air pressure. No furnace is needed. For 3D printing, the gelatin mix is extruded at body temperature into a chamber at about -30°C and around 1% of Earth’s pressure.

The material reaches a compressive strength of about 12 MPa, comparable to low-grade concrete, and a bending strength of around 6 MPa. Broken blocks can be recycled by dissolving the gelatin in warm water and recasting the paste. After four recycling cycles, the compressive strength was still about 11.8 MPa.

Still at Small Scale

The tests remain small. The largest printed piece is about the size of a wine cork, and all samples were made on Earth with inert sand rather than Martian regolith. Whether the yeast can survive Martian radiation is unknown, and tensile strength, airtightness and weather durability have not yet been measured. The best-performing version also relies on gelatin and nutrients brought from Earth.

Qiu says the material would be strong enough for a one- or two-storey building on Earth. For architects and engineers, the research shows how biological binders and low-energy curing could offer another route to masonry-like materials.

Source: Earth.com / Interesting Engineering
Image by Ning Liu