direct shear creep characteristics of sand treated with microbial-induced calcite precipitation

Microbial-induced calcite precipitation (micp) is a promising method to improve geotechnical engineering properties. in this context, little research has been conducted on the creep behavior of micp-treated sand. therefore, the present work performed direct shear creep tests to investigate the creep-related mechanical properties of silica sand and calcareous sand grouted three, six, and nine times in the micp treatment. compared to the untreated sand, the creep deformation of the micp-treated silica sand grouted three and six times was more significant, and the creep deformation of the micp-treated silica sand grouted nine times decreased by 88.0%, indicating that the treatment of the silica sand with the micp could reduce its creep deformation. the creep deformation of the micp-treated calcareous sand was larger than that of the untreated calcareous sand except for the sample grouted three times which had a creep deformation equivalent to that of the untreated calcareous sand, implying that the treatment of the calcareous sand with the micp could increase its creep deformation. the scanning electron microscopy (sem) images demonstrated that the calcium carbonate produced by microorganisms in the voids formed a connection between the sand particles as the critical factor affecting the creep behavior of the micp-treated silica sand. in the case of the calcareous sand, the cavities were filled up with calcium carbonate, which decreased the effect of the interlocking structure of the sand particles. © 2022, iran university of science and technology.