Turning soil into stone with bacteria injections

Engineers could create flood embankments, coastal defences and other infrastructure by pumping bacteria into the ground, a researcher has suggested.

The bacteria-infused soil could offer a tough, low-carbon cement alternative, said Rebecca Lunn MBE from the University of Strathclyde. The professor will research the process, known as microbially induced calcite precipitation (MICP), during a five-year post for the Royal Academy of Engineering and construction contractor BAM Nuttall.

MICP involves engineers injecting naturally-occurring bacteria and urea solutions into soil. The bacteria precipitates calcite, a hard mineral which binds together particles, turning loose soil into rock.

The technique is “a durable, non-destructive alternative to traditional carbon-intensive construction methods,” said Lunn. Scientists have performed some small-scale trials and industrial applications around the world, but Lunn said none have happened in the UK.

“As well as testing and building confidence in the technology itself, I’ll be using my time in this research chair to tackle the challenges related to scaling it up for industrial use,” she said. “For example, how do you grow and transport sufficient bacteria? How do you implement the technology on site without requiring civil engineers to become microbiologists?”

The research will examine ways of creating homogenous hard material at sites which will be subsequently excavated and tested. Ludd hopes to find how many biomineral soil treatments are needed to achieve certain strengths, to design the best pumping strategies and to explore commercial applications.

The researcher hopes MICP could be a viable, environmentally-friendly alternative to cement, which is normally imported to sites. Ludd said the process could be useful for infrastructure such as flood embankments and coastal defences. She previously tested it sealing rock fractures during the construction of geological disposal facilities for nuclear waste.  

“Construction has a mixed record in research and development, something that our business has worked hard to change over recent years,” said BAM Nuttall director Alasdair Henderson. “We know that successfully implementing innovations like MICP leads directly to improved productivity, lower carbon demand and greater economic growth, with a beneficial effect across society.”