Pore-scale investigation of MICP in simplified pore structures through microfluidic tests

Abstract

The microstructure of microbially induced carbonate precipitation (MICP) stabilized soils is typically used to explain the macro-scale properties of the soils. However, the microstructure is usually inferred from scanning electron microscopy results after breakage, as directly observing the processes inside the pores is challenging. Microfluidics technique provides the solution for visually observing the in situ precipitation process at pore scales. This work endeavors to visually observe and quantitatively analyze the pore scale precipitation process of MICP in characteristic pore structures with the help of the microfluidics technique. Pore structure is one of the most important factors affecting the flow field in pore networks, which might further affect the transport of reactive components and the distribution of precipitates in pores. Therefore, two groups of simplified pore networks were designed to investigate the influence of pore structure. The current work gives an implication of how pore structure and flow rate influence the MICP process and precipitation efficiency at the pore scale. The results also highlight the importance of the diffusion of reactants, and the dissolution and scouring of crystals on the distribution of precipitates at pore scale.