Spatiotemporal evolution of biomineralization in heterogeneous pore structure

Abstract

A fundamental understanding of the CaCO3 precipitation process in the pore network of geomaterials is important to uncover the mechanism behind the evolution of the engineering properties of geomaterials during the microbially induced carbonate precipitation (MICP) treatment. However, the details about the CaCO3 precipitation process and its interaction with the flow field at the pore scale are not well understood. In the current work, the CaCO3 precipitation process and flow field in a heterogeneous chip composed of two pore bodies, four pore throats of different sizes, and two dead-end pores are presented. The test results show that solutions can percolate through all four pore throats and diffuse into the dead-end pores at the beginning of the tests. As a result, CaCO3 can be precipitated across the chip with some difference in the number, shape, and size of crystals. Fine pore throats are more likely to be clogged, leading to solution percolating through coarse channels, thereby increasing the amount of CaCO3 in coarse channels. Precipitation in coarse channels is also ceased after a certain duration despite the continued injection of the solution. Our work provides insight into the CaCO3 precipitation process in a representative pore element, which can help to understand the mechanism behind the evolution of engineering properties and establish simulation models to predict the engineering properties of geomaterials treated by the MICP method.