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There are three main electrochemical factors affecting the electroosmotic flow in clay soil: the voltage loss at the clay/electrode interface, the type of current carriers in the soil, and the ion composition change in the clay due to voltage application. Appropriate evaluation of these factors is important to cost effectively implement electroosmosis for in situ soil consolidation projects. In this study, three different experimental systems were developed and used to investigate electrochemical reactions occurring in reconstituted and natural marine clay during electroosmotic consolidation. The results of polarization tests show that the voltage loss at the clay/electrode interface is different depending on the combination of the clay material and electrode material. The results of electroosmotic element test also show that electroosmotic dehydration does not increase if large current–voltage value is applied and that an optimal current–voltage value for causing electroosmosis depends on the cohesive soil composition. If the clay contains a lot of oxidizable ions, such as sodium, these ions affect electrophoresis and chemical reactions that occur in the soil. Therefore, the optimal configuration to apply electric current also differs depending on the clay. The results of laboratory-scale electroosmotic dehydration tests, arranged in a realistic in situ layout, are performed to study the relationship between soil dehydration, consolidation, and surface crack generation. [ABSTRACT FROM AUTHOR]

Corrosion of steel bars is one cause of deterioration in reinforced concrete structures. The state of corrosion of rebar in concrete structures can be measured using the AC impedance method. The typical three-electrode AC impedance method requires electrical continuity between the rebar and the measurement device, which may be inconvenient because the structure requires to be partly damaged by processes such as drilling. The present study proposes a method to obtain the same impedance spectra as the three-electrode method by modifying the electrode configuration of the four-electrode method. The procedures for such a measurement are as follows: first, place the counter electrode and the measurement reference electrode at the measurement point; place another counter electrode at a sufficient distance from the measurement point; place another reference electrode at a sufficient distance from both the measurement point and the applied counter electrode; and connect WE_I to the applied counter electrode, WE_V to the reference electrode, CE to the applied counter electrode, and RE to the applied counter electrode, and measure the impedance. In this paper, the physical experiments and the numerical experiments demonstrate the validity of the above method. Under the conditions of this physical experiment (concrete W/C = 54.2%, cover 50 mm), the distance between the measurement point and the application counter electrode was required to be about 1.3 m. The distance between the measurement point and the reference matching electrode was also required to be about 1.3 m. [ABSTRACT FROM AUTHOR]