biocement

Biocement, also known as microbial induced calcite precipitation (MICP), is a process that uses microorganisms to create a cementing agent, typically calcium carbonate. This biological approach offers an alternative to traditional cement production, which is a significant contributor to greenhouse gas emissions. The core principle involves harnessing the metabolic activity of specific bacteria. These bacteria are often found in soil or marine environments and are capable of precipitating minerals.

In a typical MICP process, a solution containing urea and a calcium source, such as calcium chloride, is introduced. When the bacteria are present, they break down the urea, producing ammonia and carbonate ions. The ammonia increases the pH of the solution, which in turn causes the calcium ions and carbonate ions to react and form calcium carbonate. This calcium carbonate then acts as a binder, filling pores and cementing soil particles or aggregate materials together.

The applications of biocement are diverse and still under active research and development. It can be used for soil stabilization, which strengthens the ground for construction purposes, and for crack repair in concrete and masonry. It also shows promise in coastal protection, creating artificial reefs, and in the remediation of contaminated soils. The environmental benefits are a major driving force, as biocement production is generally considered to be at a lower temperature and with fewer carbon emissions compared to Portland cement. However, challenges remain in scaling up the process, controlling microbial activity, and ensuring long-term durability.