In this study, iron and aluminum electrodes were put in marine clay which was taken from the south coast in Korea to increase the undrained shear strength by inducing the densification and cementation between clay particles and precipitates which were developed by electric decomposition in an electrode. To raise the cementation rate and reduce treatment time, high electric current (2.5A) was applied in each electrode at a semi-pilot scale soil box with marine clay. After the tests, the undrained shear strength was measured at designated points using a static cone penetration test device and sampling was conducted simultaneously in order to measure water content, pH and electric conductivity which would be the key for configuring the cementation effects indirectly. In the results of electric decomposition in iron electrode, the measured shear strength was increased considerably compared to the initial shear strength because of the cementation effect between iron ions and soil particles. In the case of an electric decomposition test in aluminum electrodes, the distribution of measured shear strength and degree of improvement were more homogeneous than that of iron electrodes.
In general, the electrokinetic (EK) phenomenon is developed when direct current (DC) electric fields are applied in fully saturated clay. The following phenomenon would occur under the influence of the DC electric fields. (1) Pore fluid flows from anodes to cathodes (Called electro-osmosis), (2) Positively charged dissolved ions flow from anodes to cathodes (Called electro-migration), and (3) Negatively charged soil particles move from anodes to cathodes (Called electrophoresis). The geotechnical characteristics of fine-grained soils could be improved by using suggested EK phenomenon through the dewatering and consolidation process.
Present research from reports shows that the iron oxide and carbonate precipitates would induce the effect of densification in soil when DC electric fields were applied in marine clay.