Stiffness and Dilatancy Improvements in Uncemented Sands Treated through MICP

Laboratory testing shows that microbially induced carbonate precipitation (MICP) through microbial denitrification can improve the mechanical properties of a sand without inducing significant interparticle cementation. Consolidated isotropically undrained triaxial compression testing of Ottawa 20–30 sand treated with denitrifying microorganisms shows that, even at low carbonate contents and with no observed cementation, soil treated through MICP exhibits significantly improved stiffness and dilatant behavior. These improvements are also evident when the treated soil is dried, reconstituted, and retested, indicating that the stiffness and dilatant properties of the soil can be improved by MICP in the absence of interparticle cementation, particularly at low strains. However, these improvements may be reduced or eliminated when the soil is reconstituted and tested multiple times. These results indicate that small amounts of MICP can induce significant improvement in treated soils, potentially leading to savings in time and money if this technology is applied in the field.