Mining and using underground resources demand high water usage, producing significant waste with environmental risks. Methods like electrokinetics prove effective in accelerating dewatering and stabilizing structures. This research provides the results of experimental investigation on dewatering silty tailings obtained from Sungun Tailings Dam (East Azerbaijan, Iran) using the electrokinetic water recovery method. Previous studies primarily examined the electrokinetic process in steady-state flow and saturated soil, with limited exploration of unsaturated soil parameters. In this research, the electrokinetic process in steady-state flow was initially investigated, and the saturated electro-osmotic permeability was determined. Subsequently, experiments were conducted in non-steady-state flow and unsaturated conditions, measuring the influential parameters with soil moisture sensors and tensiometers. Results show that decreasing sample moisture through electro-osmotic flow increases negative pore water pressure. Tailings' electrical conductivity is more influenced by moisture content, with a steeper reduction slope concerning volumetric moisture reduction over time. pH assessments show soil acidity on the anode side and alkalinity on the cathode side. Higher applied voltage gradients result in increased maximum power consumption. Importantly, the results caution against assuming that higher applied voltage improves the electro-osmotic process, as it may lead to issues such as deep sample cracking, void space creation, interrupted electrical flow, and energy loss.

This study investigates the influence of four soil improvement methods-microbially induced carbonate precipitation (MICP), electrokinetics (EK), chemical additives, and a combination of EK and chemical additives-on the dispersivity, mechanical properties, and microstructure of dispersive soil. A series of tests was designed to evaluate the effectiveness of these methods on dispersive soil. Both the original and treated soil samples were tested to assess changes in soil properties, including dispersivity, plasticity, pH, unconfined compressive strength (UCS), shear strength, and microstructure. Dispersivity was assessed using pinhole tests, crumb tests, double hydrometer tests, and exchangeable sodium percentage tests. The experimental results indicate that the combined EK and chemical additives method significantly reduces the dispersivity and plasticity of the dispersive soil compared with the other methods, leading to improved UCS. The EK and chemical additive methods individually demonstrate effective modification under a voltage of 48V and an additive content of 4%, respectively, enhancing the shear strength of the dispersive soil. MICP does not significantly improve the dispersivity of dispersive soil, but it does enhance the shear strength of the treated soil, with a particularly notable increase in the internal friction angle. Overall, the combined method shows more remarkable improvements in the dispersive soil than any single method. In summary, the combination of EK and chemical additives has significant potential for improving the dispersivity and mechanical properties of dispersive soil.

Sand aging, defined by time-dependent increases in stiffness and strength over periods ranging from days to months, poses significant challenges in geotechnical engineering and soil science. Despite its relevant implications, the mechanisms driving sand aging remain understood. This review systematically examines sand aging, emphasizing the classification of chemical and mechanical processes involved. Key advancements in chemical aging understanding, particularly the influence of surface chemistry and electrokinetic forces, are discussed. Additionally, the review underscores the critical role of micromechanical modeling, especially discrete element methods, in elucidating particle interactions and aging phenomena. The review also identifies essential directions for future research, notably incorporating particle shape and surface texture into aging models. Hence, this comprehensive resource aims to enhance the understanding of sand aging.

This study proposes a closed-form solution for axisymmetric electro-osmotic consolidation of unsaturated soil under semi-permeable boundary conditions. The governing equations are formulated to allow for vertical and radial flows of liquid and air phases. The techniques of eigenfunction expansion and Laplace transformation are employed to develop the exact solution for excess pore-air (EPAP) and pore-water pressures (EPWP). The proposed solution is first validated by comparing it to an existing solution, followed by verification through finite element simulations. Both methods of validation confirm the accuracy of the analytical solution. Then, based on the obtained solution, the effects of vertical flow, semi-permeable boundary conditions, electrical voltage, electro-osmosis conductivity and spacing ratio re/rw on the consolidation profile have been further investigated. Parametric studies show that the EPWP at the steady state depends on the electro-osmosis conductivity and applied electricity gradient. In addition, the dissipation rates of EPWP and EPAP in the axisymmetric electro-osmotic consolidation would be underestimated if the vertical flows are neglected. The semi-permeable boundary conditions have great influences on the dissipation rate and the steady-state solution. The proposed solution could serve as a theoretical basis for axisymmetric electro-osmotic consolidation of unsaturated soil.

Soil electrokinetic (SEK) is a remarkable technology that has applications in a variety of fields, such as polluted soil remediation, soil restoration, geophysics, dewatering, seed germination, pollution prevention, sedimentation, and consolidation. The current review is a continuation of our recently published series on process design modifications and material additives. There are three reviews have been recently published. The 1st and 2nd reviews were focused on SEK classification according to electrode position/types of contaminants movement (horizontal, vertical, and mixed horizontal and vertical) during (1993-2020) [1] and (2021-2022) [2], respectively. The 3rd review summarized the materials additives for enhancing the SEK intensification process during 2017-2020 [3]. Modifications were made to the shape of the electrodes to make research and operation more convenient and efficient. Based on exhaustive searches in six scientific search engines, we focused on the various roles of utilizing the perforated electrodes, pipes (a tubular section, or hollow cylinder, made of hard plastic), and nozzles (a tubular section, or hollow cylinder, made of flexible plastic) (PEPN) during SEK. The PEPN could perform SEK properly, remove nitrate, collect drainage water, reduce pH advection, enhance materials injection, distribute water throughout treated soil, incorporate a vacuum system, and monitor wells. Although the perforated electrodes may be considered an economic advantage due to the reduction of electrode surface area and, consequently, total costs, no comparative studies have been conducted to determine the effects of different electrode surface areas on the SEK efficiency, operation time, and energy consumption, which should be considered in future research.