New technique could help turn Mars or moon rocks into concrete
Researchers have developed a form of concrete that humans could produce on Mars or the moon – and that might have important benefits here on earth.
NASA would like to send humans to Mars by 2030. Elon Musk, CEO of SpaceX, says his private launch company could do it as early as 2024. But if humans actually do reach Mars, or even establish settlements on the moon, they would need thousands of tons of concrete to survive. Since it’s impossible to ship tons of cement from Earth to Mars, the best bet is for humans to start making it when they arrive.
Promising concrete with animal protein
The problem is that making earth-style concrete requires tremendous amounts of heat and energy, because you have to cook limestone to create the binding agent that holds concrete together. To solve that problem, NASA-researchers reached out to Michael Lepech, an associate professor of civil and environmental engineering at Stanford School of Engineering. Lepech focuses on increasing environmental sustainability in construction, including ways to reduce the energy used in making concrete.
Concrete bound together with a protein
Indeed, the production of concrete accounts for 5% of all human-generated carbon emissions. It’s the binding agent – the boiled limestone – that accounts for much of that. In search for a less energy-intensive alternative, the researchers turned to biology. Living organisms use proteins to make things as tough as shells, bones and teeth, so the researchers began working on a concrete bound together with a protein from bovine blood. The protein is a fairly cheap by-product of slaughterhouses, and it is known to become very gluey when mixed with soil.
Replicate the conditions on Mars & moon
To replicate the conditions on Mars and the moon, Lepech has combined the protein with simulated extraterrestrial soils that are similar to what’s on Mars and the moon. And because Mars has much lower gravity than earth – bad for cement mixing – the researchers did their mixing with a vacuum technology that is used to make the composite materials in products such as boat hulls.
Heavy rain degrades new concrete
Lepech says that bio-concrete isn’t yet ready for buildings and roads on earth – but that it could be. In a paper, he and his colleagues found that heavy rain will degrade the new concrete over a period of years. However, the researchers say there are many opportunities to improve the durability and efficiency, in part by tweaking the proteins as well as by becoming more efficient in production. One of the big advantages of bio-based concrete is that, unlike in regular concrete, the binding proteins can be recycled time after time. Over years, that can save a lot of energy.
