Settlers on Mars might be able to turn the planet's red soil into bricks without having to use an oven or additional ingredients, a new study using simulated Martian soil found. Instead, the inter-planetary colonists would just need to apply pressure to compact the soil with the equivalent force of a blow from a hammer.
Proposals to use Martian soil to build habitats for manned missions on the planet are not new. But this is the first that shows astronauts would need minimal resources to do so. Previous plans included nuclear-powered brick kilns or using complex chemistry to turn organic compounds found on Mars into binding polymers.
A team of engineers at the University of California San Diego were initially trying to cut down on the amount of polymers required to shape Martian soil into bricks, but accidentally discovered that none was needed.
To make bricks out of simulated Martian soil without additives and without heating or baking the material, two steps were key. One was to enclose the soil in a flexible container, in this case a rubber tube. The other step was to compact the soil at a high enough pressure. Researches found that the amount of pressure needed for a small sample is roughly the equivalent of someone dropping 10-pound hammer from a height of one meter.
The process produces small round soil pallets that are about an inch tall which can then be cut into brick shapes. The engineers believe that the iron oxide, which gives Martian soil its signature reddish hue, acts as a binding agent. They investigated the simulated soil's structure with various scanning tools and found that the tiny iron particles coat the soil's bigger rocky basalt particles. The iron particles have clean, flat facets that easily bind to one another under pressure.
Researchers also found that even without rebar, the Martian bricks are stronger than steel-reinforced concrete.
The findings of the NASA-funded study were published in Scientific Reports on April 27, 2017.
Image credit: Jacobs School of Engineering/UC San Diego