Predictive modeling of dielectric heating in porous foods is challenging due to their nature as multiphase materials. To explore the relationship between the topological structure of multiphase foods and the accuracy of dielectric mixture models, the degree of anisotropy of two cooked rice samples with 26 and 32 % porosity was determined, and their dielectric properties were estimated using the Lichtenecker (LK), Landau-LifshitzLooyenga (LLL), and Complex Refractive Index Mixture (CRIM) equations. These properties were used in a predictive finite-element model for reheating an apparent homogeneous rice sample on a flatbed microwave (MW) for 120 s. The results were compared with experimental data and a validated two-element model. Unlike LK and LLL equations, the CRIM equation predicted heat accumulation towards the edges of the container at the two values of porosity ratio evaluated, in accordance with the experimental results and the isotropic nature of the sample. The simulated temperature distributions suggest that the three evaluated equations could predict the MW heating behavior of rice to some extent, but that in order to obtain more accurate results, it could be useful to obtain an empirical topology-related parameter specific for this sample. These results can provide insight on the relationship between the topology of the porous structure in the sample and the adequacy of different dielectric mixture models.

Water-induced disintegration is a critical issue in soil stabilization. In this study, soda residue (SR) and fly ash (FA) were mixed to improve the properties of high liquid limit clay (HLC), forming soda residue-fly ash stabilized clay (SRFSC), with cement and/or lime for further stabilization. The mix proportions of the SRFSC were optimized by the orthogonal method, using the compaction, unconfined compressive strength, shear, and disintegration tests. Meanwhile, microscopic tests were performed to reveal the possible mechanical mechanisms. The results showed that the SR and FA content are the primary determinants influencing the mechanical properties of SRFSC. When the base proportion is 70 % SR + 20 % FA + 10 % HLC, the strength is highest (2.45 MPa). At this proportion, the specimen with no cementitious material exhibits the best water disintegration resistance (WDR), reaching 107 min. Adding cement and lime can significantly enhance the WDR of the SRFSC, from complete disintegration at 0.28 min to remaining intact after soaking for 28 days. During field application, the cementitious materials content can be adjusted according to the actual conditions. The superior mechanical properties and WDR of SRFSC are mainly due to the good gradation and dense microstructure. The soda residue can provide abundant Ca2+ to enhance both the mechanical properties and WDR of SRFSC.

Improving soil properties by adding stabilizing materials, such as cement, has garnered significant attention from researchers, particularly for enhancing soils often deemed poor geotechnical quality. This approach becomes even more advantageous when applied to increase the stability of mining tailings deposits and ensure environmental safety. This study investigates the effects of cement addition and dry density on the strength and durability of compacted bauxite tailings-cement blends. The porosity/cement index, widely used in soil-cement mixture research, was adopted to analyze the parameters that control the strength and durability of these blends. Results demonstrate that increasing cement content and dry density significantly improves unconfined compressive strength (qu) and reduces accumulated mass loss (ALM) during wet/dry cycles. The porosity/cement index effectively describes the variations in qu and ALM, as expressed by an empirical equation, which can be highly beneficial for the practical application of treated mining tailings as construction materials.

The shear strength of compacted bentonite is crucial for preventing tilting and damage of the waste canisters in deep geological repositories (DGRs). The shear strength evolution along the confined wetting path also needs to be investigated, given the long saturation time of the bentonite buffer. This study conducted direct shear tests on densely compacted Gaomiaozi bentonite after suction control under confined conditions to determine its peak shear strength and strength parameters. Furthermore, the shear strength evolution along the confined wetting path was modeled on the basis of the effective stress principle. The results show that, for a given dry density, the peak shear strength at a given vertical pressure and the strength parameters exhibit an overall decrease along the confined wetting path. Moreover, the peak shear strength of the specimen that underwent confined wetting was considerably lower than that of the as-compacted specimen with the same total suction, indicating that the suction value and microstructure codetermine the peak shear strength of compacted Gaomiaozi bentonite. For this reason, the peak shear strength in the as-compacted state and the dual-porosity water retention curves established along the confined wetting path were used to model the shear strength evolution along the confined wetting path. The substitution equation for the effective stress parameter chi was selected on the basis of the experimental evidence. Finally, the model parameters were calibrated from the shear strength evolution at a given vertical pressure, and they reasonably reproduced the shear strength evolution under other vertical pressures. These findings can be helpful for the design and safe operation of DGRs under extreme geological conditions.

Three approximate analytical solutions for the problem of the seismic response of two rigid cantilever walls retaining a transversely isotropic poroelastic soil layer over bedrock are presented under conditions of plane strain and time harmonic ground motion. These approximate solutions come as a result of various reasonable simplifications concerning various response quantities of the problem, which reduce the complexity of the governing equations of motion. The method of solution in all the cases is the same with that used for obtaining the exact solution of the problem, i.e., expansion of response quantities in the frequency domain in terms of sine and cosine Fourier series along the horizontal direction and solution of the resulting system of ordinary differential equations with respect to the vertical coordinate in conjunction with the boundary conditions. The first approximate solution is obtained on the assumption of neglecting all the terms of the equations of motion associated with the fluid acceleration. The second approximate solution is obtained on the assumption that the fluid displacements are equal to the corresponding solid displacements. The third approximate solution is obtained as the sum of the second approximate solution for the whole domain plus a correction inside a boundary layer at the free soil. All three approximate solutions are compared with respect to their accuracy against the exact solution and useful conclusions pertaining the approximate range of the various parameters, like porosity, permeability and anisotropy indices, for minimization of the approximation error are drawn.

High-plasticity soils such as alluvial clay deform easily under heavy loads due to their strong plastic behavior. The tendency of these soils to expand and contract can cause deformation and cracking in structures, posing challenges in construction. To address these challenges, it's essential to improve these soils to enhance their strength and reduce plasticity before construction. Therefore, this study aims to evaluate the applicability of marble dust as a sustainable alternative to Portland cement in ground improvement applications, specifically to improve the behavior of alluvial clay. The performance of marble dust, Portland cement, and alluvial clay mixtures was evaluated using unconfined compressive strength (UCS), shear wave velocity, and mass loss due to weathering. The study tested three Portland cement contents (7, 10, and 13 %), two dry density (1.6 and 1.8 g/ cm3), and two marble dust contents (0, 10 and 20 %) across three curing ages (7, 28, and 60 days). Micro- structural analysis was performed using SEM. Results indicated a slight decrease in 7-day strength (up to 8.3 %) with 10 % marble dust replacement due to minimal pozzolanic activity, while 28-day strength loss was less significant. On the other hand, the 60-day strength increased up to 20 % upon replacing 10 % of cement with marble dust. The marble dust addition also increased the shear modulus of the soil by up to 9 % when compared with cement only. The adjusted porosity index of 0.32 correlated unconfined compressive strength (qu), initial shear modulus (G0), and accumulated loss of mass (ALM) across varying densities and blend proportions. ALM increased linearly with wet-dry cycles, with higher compaction and binder content reducing mass loss per cycle. More marble dust, however, led to greater mass loss at both curing ages, attributed to reduced cement content.

The clogging of porous media with solid particle suspension flow is modeled using two empirical parameters of filtration coefficient (7) and formation damage coefficient (/3). These parameters are typically determined through coreflood tests. This study employs machine learning techniques to predict 7 and /3 using experimental data from open literature. The prediction of /3 is based on critical porosity fraction (gamma) data and a power law equation relating /3 and gamma. Collected data were randomly partitioned into training (80 %) and testing (20 %) subsets. Four regression algorithms were employed, treating 7 or gamma as the target variable, with injection velocity (um), particle concentration (Cin), and ratio of mean pore size (Dpore) to mean particle size (Dp) as features. The extreme gradient boosting (XGBoost) algorithm showed the best performance. The feature Cin had the highest influence on 7 and gamma, revealing a significant finding previously overlooked. Postmortem analyses revealed qualitative consistencies in 7 results, supporting the existence of critical velocities. Furthermore, 7 results showed a power law relation between 7 and all three features used. An equation was formulated to estimate 7 as a function of these three features. A direct prediction of /3 using these features was established by applying the XGBoost model to predict gamma and then employing an existing power law relationship between /3 and gamma. This study demonstrated that machine learning offers an alternative approach for predicting 7 and /3, which is particularly useful for initial evaluations of clogging potentials and identification of experimental conditions to focus on.

Predisintegrated carbonaceous mudstone (PCM) that exhibits low strength and continuous disintegration is prone to wetting deformation after repeated seasonal rainfall. A reasonable assessment of wetting deformation is required to facilitate the settlement control of the PCM embankment when exposed to repeated rainfall. Herein, to reveal the wetting deformation mechanism of the PCM subjected to drying-wetting cycles, the effects of drying-wetting cycles on the wetting deformation characteristics of the PCM are investigated using the double-line method. Microscopic pore characteristics of the PCM under different drying-wetting cycles were analyzed through scanning electron microscope (SEM) micrographs. Comparative analysis of the wetting deformation data between the tests and the constitutive model considering the damage of drying-wetting cycles was carried out. The results showed that the deviator stress-strain relationship curves of the PCM exhibit the strain hardening without obvious peak and no strain softening phenomena. The critical wetting strain of the PCM was positively correlated with the number of drying-wetting cycles, while the critical deviator stress decreased with an increase in the number of drying-wetting cycles. As the number of cycles increased, the gelling material between the particles dissolved, the volume of pores inside the PCM increased, and the number of pores inside the PCM decreased. The porosity of PCM had a significant quadratic function with the number of drying-wetting cycles. A wetting deformation damage model was developed to calculate the wetting deformation of the PCM by considering the effects of drying-wetting cycles, which can be useful for evaluating rainfall-induced settlements of relevant engineering structures made from PCM.

The mechanical properties of faecal sludge (FS) influence its moisture retention characteristics to a greater extent than other properties. A comprehensive fundamental characterisation of the mechanical properties is scarcely discussed in the literature. This research focused on bulk and true densities, porosity, particle size distribution and zeta-potential, extracellular polymeric substances, rheology and dilatancy, microstructure analysis, and compactibility in the context of using the FS as a substitute for soil in land reclamation and bioremediation processes. FSs from different on-site sanitation systems were collected from around Durban, South Africa. The porosity of the FSs varied between 42% and 63%, with the zeta-potential being negative, below 10 mV. Over 95% of the particles were <1000 m. With its presence in the inner part of the solid particles, tightly bound extra-cellular polymeric substances (TB-EPSs) influenced the stability of the sludge by tightly attaching to the cell walls, with the highest being in the septic tank with the greywater sample. More proteins than carbohydrates also confirmed characterised the anaerobic nature of the sludge. The results of the textural properties using a penetrometer showed that the initial slope of the positive part of the penetration curve was related to the stiffness of the sludge sample and similar to that of sewage sludge. The dynamic oscillatory measurements exhibited a firm gel-like behaviour with a linear viscoelastic behaviour of the sludges due to the change in EPSs because of anaerobicity. The high-TS samples exhibited the role of moisture as a lubricating agent on the motion of solid particles, leading to dilatancy with reduced moisture, where the yield stress was no longer associated with the viscous forces but with the frictional contacts of solid-solid particle interactions. The filtration-compression cell test showed good compactibility, but the presence of unbound moisture even at a high pressure of 300 kPa meant that not all unbound moisture was easily removable. The moisture retention behaviour of FS was influenced by its mechanical properties, and any interventional changes to these properties can result in the release of the bound moisture of FS.

The global reserve of sand has significantly decreased, and sand washing is predominantly favored due to its simplicity and low operational costs, but this method poses significant environmental risks like landslides, making its reuse essential for sustainability. In view of this challenge, based on the composite preparation method, an innovative approach was proposed to prepare an artificial soil substrate from sand-washing slurry. The physical and vegetative feasibility performance, including strength, density, water absorption, retention, electrical conductivity (EC), and pH; and microstructural characteristics, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR) of the artificial soil substrate with different proportions of cement and foaming agent were measured. Increasing the cement content to 30% of un-crushed artificial soil substrate specimens improved strength, whereas 40% reduced it due to the diminished pore-filling effect. Water absorption rates ranged from 29.22% to 36.68%, increasing with more foaming agent and decreasing with more cement, while the water retention time was 12-14 days, and incorporating foaming agent significantly increased water absorption. Leachate pH ranged from 11.99 to 12.18, and reduced to 7.82-8.28 with 5% phosphoric acid. The EC of the artificial soil substrate decreased by 88.64% to 93.59% after 10 wet-dry cycles, aligning with the standard. Artificial-soil-substrate-predominant products include calcite, quartz, and dolomite, with a pronounced silica content and soil substrate porosity ranging from 27.96% to 51.80%. From the microstructural test, calcium silicate hydrate gel, produced by cement hydration, effectively bound the sand-washing slurry, thereby improving strength.