Bacterial Concrete

This research presents the results of a study in which natural microbial biological processes were used to engi- neer a cemented soil within loose sand. Microbially induced calcite precipitation (MICP) was achieved by Jason T DeJong and his team at UC Davis, CA using the microorganism Bacillus pasteurii, an aerobic bacterium per- vasive in natural soil deposits. The microbes were introduced to the sand in a liquid growth medium amended with urea and a dissolved calcium source. Subsequent cementation treatments were passed through the sand

to increase the cementation level of the sand. In short, the bacteria turnes sand into sandstone. The starting point of the research was to find cure to a problem that is called liquefaction, which occurs during earthqua- kes causing ground to loose its bearing force and behave like a liquid. This phenomenon causes houses to sink. Jasons application was to restablish the firmnes in the soil through cementating the soil using the bacteria.

Another application to Jasons research was the Swedish arcitecture student who also found interest in this parti- cular microorganism. His application of the Bacillus Pasteurii, is to stop the desertification. The aim is to use it like a giant 3D printer where the sand is the dust and the bacteria the adhesive. The initial reactions finish within 24 hours; it would take about a week to saturate the sand enough to make the structure habitable. The bacteria are non-patogenic and die in the process of solidifying the sand.

The stable dune-like formations which not only stabilize the sand dunes but also provide shelter for people.

Calcite cementSand dunes

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