Testing in the lab and in real conditions
To see if the freeze-dried bacteria still worked, researchers tested them in the lab. They placed the bacteria in 3D-printed molds filled with different types of sand and soil. After spraying them multiple times with calcium chloride and urea, the bacteria produced biocement. The strongest biocement formed in play sand, while sandy soil also became solid but not as strong.
Next, the team filled PVC pipes with sandy soil and treated them with the freeze-dried bacteria. These columns became stronger as they were exposed to more calcium chloride and urea, showing that the bacteria could still produce biocement even after being frozen and stored.