Disruptions of MICP Bonds between Spherical Cone Grains

Abstract Microbially induced calcium carbonate precipitation (MICP) technology has garnered considerable interest in the area of sand stabilization. However, few studies have examined the influence of grain morphology on intergrain MICP bonds. In this study, we carry out grain-scale compression tests aimed at revealing the failure mechanisms of MICP-treated spherical-cone specimens. The results indicated that the specimens exhibit three failure modes, i.e., the tensile failure accompanied by grain breakage, the shear failure along the calcium carbonate–grain interfaces, and the single-grain detachment failure. With an increase in the grain apex angle in the specimens, the average peak force increases progressively, whereas the average peak secant stiffness slightly decreases at a higher apex angle. We provided empirical equations for capturing the strength and stiffness regarding the calcium carbonate. Based on the scanning electron microscopy results, we found that the differences in specimen strength and failure modes could be caused by the heterogeneous precipitation of calcium carbonate between grains. The valuable findings in this study could benefit the numerical model and constitutive model of biotreated specimens.