According to EU Science Hub, more frequent extreme weather events will cause more and more damage to infrastructure. The losses by 2030 will amount to 20 billion euros per year, according to the latest estimates. These threats are drawing scientists’ attention to the need for new answers to the problem of soil stabilization. Scientists at the Soil Mechanics Laboratory (LMS) of EPFL have developed a number of solutions, one of them using enzyme metabolism. In an article published today in Scientific Reports, a team of scientists demonstrates how chemical reactions can be improved by using a battery system to supply electrical current.
A new type of biocement, produced locally and at ambient temperature, has recently been proposed as a promising method to stabilize different types of soils. This method uses bacterial metabolism to produce calcite crystals that firmly bind the soil particles together. This biogeochemical process is energy efficient and cost-effective, so it can be quickly deployed in the coming years. But since the soil needs to be impregnated for the method to work, it is less suitable for clay soils with low water permeability. For this reason, the LMS team has developed and successfully tested a viable alternative, which includes the use of electric current with recessed electrodes.
“Our results show that this geoelectrochemical system really influences the key stages of the calcification process, especially the formation and growth of crystals that bind the soil together and improve its “behavior”,” explains Demetrios Terzis, LMS scientist and one of the authors of the article.
Biocement is formed by the introduction of chemicals into the soil. These include dissolved carbonate and calcium ions, which carry opposite charges. Sunken anodes and cathodes are used to create an electric field, almost like a giant battery. Current forces the ions to move through a medium with low permeability, where they meet, mix and eventually interact with the soil particles. The result is the growth of carbonate minerals that act as links or “bridges” to improve the mechanical characteristics and resistance of the soil.
In the past, soils were viewed solely as a mixture of solid earth, air and water. According to the co-authors of the study, their work emphasizes how interdisciplinary approaches – namely, the use of concepts of biology and electrochemistry and the use of advances and mechanisms from other scientific fields – can open up significant benefits and solve pressing problems.