Abstract

With rising interest in the use of bio-technologies in geotechnical engineering, an increasing number of researchers have been exploring their use for different applications. In this talk the use of an innovative biological technology, namely microbial carbonate precipitation (MCP) will be discussed. The precipitation of calcium carbonate (CaCO3) in sand results in its cementation which could be utilized in numerous applications such as slope stability, facilitating excavation and tunnelling, soil improvement against soil liquefaction, and foundation settlement reduction. Factors such as concentrations of chemical reactants required for the process to happen (calcium and carbon sources), their input rate and how to introduce them to the targeted areas were studied. It was found that below a chemical input rate of 0.042 mole/litre/hr, the process efficiency would be over 90%. However, SEM images showed that the calcite precipitation pattern is affected by the injected concentration. The use of the bio-cementation process in soil improvement, modification of soil hydraulic properties, and carbon dioxide mineral sequestration was also studied. Unconfined compressive strength (UCS) and permeability experiments were conducted for samples during cementation, and strength and permeability were correlated with the amount of precipitation. It was found that the results also varied with the use of different chemical concentrations. An overview of the process as well as the results produced in the topic over the past three years will be presented. Furthermore, the main question of whether this bio-chemical process could actually provide sustainable environmental-friendly solutions for different geotechnical domains will be discussed.