Spectral induced polarization study on enzyme induced carbonate precipitations: influences of size and content on stiffness of a fine sand

Heterogeneity in either chemically or microbiologically induced carbonate-based ground improvement methods is a major obstacle in engineering application. Spectral induced polarization (SIP), an innovative and nondestructive method, which has demonstrated promise in monitoring microbial activity, was used in this study to monitor enzyme induced carbonate precipitation (EICP). The complex conductivities, together with the shear wave velocities (V-s), of an EICP modified sand were monitored using a self-developed spectral induced polarization-bender element column. The mean precipitate size was calculated by relaxation time (tau) and the Schwarz equation. The precipitate contents were calculated by cumulative gamma distribution function on the global polarization magnitude (m(n)) withR(2) = 0.989. The stiffness of the enhanced geomaterial, in terms ofV(s), correlates tom(n)with a cumulative lognormal distribution function withR(2) = 0.967. Contact cementation was postulated as the dominant association pattern. The possible mechanism for this may be the formation of eddies and the nucleation of CaCO(3)crystals during precipitation. The results suggest that SIP can be used as an effective nondestructive monitoring tool to assess the stiffness of geomaterials.

Automated summary

The study used spectral induced polarization to monitor enzyme-induced carbonate precipitation, showing that SIP is an effective nondestructive monitoring tool for assessing the stiffness of geomaterials.