Enhanced Strength Properties of Dredged Marine Sediments Using Electrokinetic Stabilization Method

Nearshore’s facilities are often require frequent and regular maintenance dredging in maintaining appropriate water depths and enlarging the access channel and turning basin. A large amount of sediment was spawned from the dredging work. The dredged marine sediments (DMS) are not apt to be used in construction activities because of its poor geophysical properties. The purpose of this research is to study the improvement in moisture content and strength of DMS by using electrokinetic (EK) method. DMS are classified as a high plasticity silt (MH) with 240.74 % of its natural water content. Stainless steel plate was invoked as the electrode, while distilled water (DW), citric acid (CA) and calcium chloride (CaCl2) were applied as the stabilizing agents. The aforementioned stabilizers are electrically injected into the DMS which causing flow of the solutions through the pores in DMS under 50 V/m of applied direct current (DC). The results of treated DMS are presented in moisture content, undrained shear strength and SEM-EDX analysis. The EK treated DMS shows it increases in strength in the dry zone area after the 14 days treatment. The dry zone area was created near the anode and wet zone was made near the cathode. The application of calcium ions in the treatment had increased the strength and alters the pattern of the soil fabric. Largely, EK has significantly improved the quality of DMS even though the strength increase observed was not homogeneous throughout the specimen.

Effect of polyaniline-coated galvanized steel electrodes on electrokinetic sedimentation of dredged mud slurries

An experimental study on electrokinetic improvement of dredged marine sediments to accelerate their sedimentation for land reclamation purposes is presented. Electrokinetic stabilization is currently used to improve soils; however, its use on soils with marine sediments with low permeability is still questionable due to the deterioration of anodes caused by an electrolysis reaction. A number of traditional methods are employed in literature to reduce the corrosion degradation of metals, such as painting, galvanizing, and conversion coating. Conducting polymers, e.g., polyaniline, are of engineering interest due to their properties such as ease of preparation and their high environmental stability in protecting metals from corrosion. For this purpose, the anodes used in the electrokinetic testing cell herein were coated with polyaniline to investigate the effect on electrokinetic stabilization of the dredged mud. Two series of experiments were performed using a polyaniline-coated galvanized steel anode, and two series of experiments with noncoated galvanized steel anodes were also carried out as a control. Depending on the applied voltage, the settlement and electroosmotic permeability of the dredged mud varied during the process. Polyaniline coating increased the power consumption during the electrokinetic stabilization compared to the case where the same electric potential was applied using the uncoated electrodes. However, when 5 V electric potential was applied to the soil through the polyaniline coated anode, its settlement and electroosmotic permeability were equivalent to what was observed with the 30 V electric potential applied through the noncoated anode, with 3 times less energy consumption.