WWII battleship made from ice inspires strong new building material

A new kind of “super ice” that has its origins in a wild World War II plan to build ships from ice and wood pulp could give future engineers a novel toolkit for construction in polar or even alien environments.

Developed by researchers from the Hebrew University in Israel, the genetically engineered material is reportedly 10 times stronger than pure ice, reigniting interest in sustainable ice-based construction.

The idea’s foundations are right out of a James Bond movie. Take an iceberg, level off the top, and create the biggest aircraft carrier the world has ever seen.

With steel and aluminum in limited supply in World War II, Allied forces gave serious consideration to a proposal made by English inventor Geoffrey Pyke to build ships out of little more than frozen water.

Known as Project Habakkuk, the plan barely made it past the chin-scratching phase. Nobel Laureate for chemistry, Max Perutz, pointed out that natural icebergs were neither big enough nor stable enough to do the job safely, leaving Pyke to consider novel ways to turn water into a novel building material.

His solution was to mix in wood pulp for a durable form of ice. Easy to cast and machine, cheap to manufacture, the material – dubbed Pykrete – showed some promise. If not for the sudden availability of long-distance ocean transport (not to mention constant engineering challenges and the escalating cost of the plan), D-Day may have required far more woollen socks.

Pykrete has remained more of a curiosity among engineers than a potential super material, despite the desire for sustainable construction materials.

According to the Hebrew University researchers, the material’s strength is limited by the disordered distribution of wood’s cellulose fibers. Reducing their size and binding the fine mesh into a 3D scaffold would go a long way to making ice more concrete-like.

For the “glue”, the team genetically modified a natural ice-binding protein found in fish by adding a component that also sticks to carbohydrates. Mixed into a suspension of cellulose nanoparticles and then frozen, the customised chimera formed a flexible molecular skeleton that dramatically increases the tensile strength of the surrounding ice.

"We wanted to go beyond simply mixing fibers into ice and instead control how the different materials connect at the molecular level," says senior author and biochemist Ido Braslavsky.

"The result changes not only how strong the ice is, but also how it breaks. Instead of suddenly shattering, it can absorb much more energy and deform gradually."

Laboratory testing showed that cylinders made from resulting Biopykrete can absorb 70 times more energy than pure ice before cracking, making the material “a promising proof-of-concept and a candidate worth evaluating for Arctic and Antarctic applications.”

It’s easy to imagine transporting a small jar of Biopykrete-producing E. coli into the Arctic wilderness or across the interplanetary expanse to the Martian poles or a Jovian moon for a robust instashelter (just add water!). And if this experiment is anything to go by, Pyke’s concept – with a granular, genetically engineered twist – holds water.

Sustainable scaling may yet be an issue, however. It’s one thing to force an engineered culture of bacteria to cough up enough of the glue for a few sample cylinders. To deliver enough for even a small building, a functional brewery would need to be constructed – without emitting a bunch of carbon dioxide or risking your microbes.

Just as Pyke learned, a vast chasm lies between a cool idea and a practical building material.

Yet one day, another team of engineers could very well take the idea of a chimeric protein engineered by microbes and make an even better ice-based building material. One that could truly turn water into the biggest floating fortresses the world has ever seen.

This research was published in Colloids and Surfaces B: Biointerfaces.

Source: Phys.org