Microbial Mineralization and Carbonation Consolidation of Dredger Fill and Its Mechanical Properties

Abstract

Streptomyces-induced calcite precipitation (SICP) was used to bind loose dredger fill into soil columns. The composition, microstructure, strength, and permeability of the soil columns were studied. The X-ray diffraction (XRD) results show that the cementitious material of calcium carbonate was found in the soil columns. The morphology of the soil columns with and without streptomyces was the sheet and the block structure, respectively. The compressive strength of the soil columns was highest (2.29 MPa) when the content of streptomyces was 30%. The compressive strength of the soil columns with streptomyces was higher than other groups when the medium solution pH was 9, although the hydraulic conductivity of the soil columns containing streptomyces (15% of calcium oxide) was similar to those without. Under the optimal bacterial powder content of 30%, the average resulting content of calcium carbonate was 12.73% in the soil columns. Compared with microbially-induced carbonate precipitation (MICP), the SICP process did not release ammonia gas during biomineralization. Therefore, the SICP technique is environmentally friendly for the cementation process.