Improvement of Coarse Sand Engineering Properties by Microbially Induced Calcite Precipitation

Abstract

This paper investigates the effectiveness of microbially induced calcite precipitation method in improving the strength and stiffness of coarse sands using treatments based on a four-phase percolation technique. An increase of biochemical treatment cycles was associated with increased deposition of calcium carbonate (CaCO₃) and consequently an increase in compressive strength. Furthermore, the bio-cemented coarse sand retained reasonable porosity and permeability, which should allow dissipation of pore water pressure if required. The results also establish a correlation between the strength gained and stiffness of the bio-cemented coarse sand with the increase in the amount of deposited CaCO₃, initial relative density and dry density. Scanning electron microscopy and electron dispersive spectroscopy analysis indicate that the inter-structure of the bio-cemented coarse sand tend to change in morphology based upon the number of biochemical treatments used.