Electro-biogrouting stabilisation of soft soil

Abstract

This paper describes a new method called electro-biogrouting for the improvement of soft soil with low hydraulic conductivity. In this method, bacteria, urea and calcium ion are injected by an applied electric field. Initially, the calcium ions are moved across the specimen by electromigration from the anode to the cathode. Then, the urea, which is non-ionic and solvable, is transported by electro-osmotic flow from the anode to the cathode. Finally, the bacteria with negative surface charge are induced as particles by electrophoresis mobility from the anode to the cathode. Polarity reversal is applied to ensure homogeneous distribution of agents. As the bacteria expose the urea, the urease enzyme is released, and carbonate ions are produced, which results in CaCO3 precipitation in the porous media of the soil. This increases the shear strength of the soil up to 1080%. The CaCO3 was detected using the acid washing technique.