Localized compressive strength profiling of sand MICP-treated by surface percolation method in 1D column

Biocementation in soils using microbially induced calcium carbonate precipitation (MICP) has recently emerged as a sustainable and environmentally friendly solution for improving the geotechnical characteristics of soils. The improvement level of MICP-treated sands varies depending upon the transportation and cementation mechanisms related to the methods of MICP implementation. Despite the conventional methods of strength measurement being used widely for MICP-treated soils, the influence of biocementation in soils resulting in a localized strength pattern has not been investigated yet. In this study, the localized strength profiling in unsaturated sand treated by MICP is carried out using a number of sand column tests under different treatment conditions. The MICP treatment was conducted using sand columns 10 cm in height and 5 cm in diameter through a surface percolation method. Unconfined compressive strengths (UCSs) along the depth of MICP-treated sand columns were measured in the form of local compressive strength through a needle penetration testing performed throughout the equally divided sections along the depth of the sand columns. The local water content and the local CaCO3 content in each section were also quantified to investigate the dependence of local compressive strength on these factors. Moreover, the microscale examination of the specimens from MICP-treated sand columns was also performed. The investigation of local compressive strength measurement in MICP-treated sand columns in this study leads to deeper understanding of the factors affecting the local compressive strength. This work is expected to be a useful contribution to optimizing the practical application of MICP technology for green infrastructure development.