Search Results (2,242)

Rainfall infiltration can alter matric suction and significantly affect the active earth pressure acting on retaining structures with unsaturated backfills. This effect becomes more complex when hydraulic layering and finite-width failure mechanisms are involved. In this study, a coupled analytical–numerical framework is developed for a vertical retaining wall with a two-layer unsaturated backfill subjected to time-varying rainfall. A one-dimensional transient seepage formulation based on the Gardner-type hydraulic model is combined with a three-dimensional kinematic upper-bound mechanism generated by double-logarithmic-spiral curves. The transient pressure head and effective saturation are converted into a suction-induced resisting contribution and introduced into the work-rate balance. The effects of initial water-content distribution, bottom hydraulic boundary condition, normalized wall width, rainfall intensity, and layer thickness ratio are investigated. The results show that the calculated active earth pressure coefficient is controlled by the coupled influence of transient suction loss, hydraulic contrast between layers, and finite-width confinement. Clay-related profiles are more sensitive to the initial hydraulic state and finite-width effect than sand-dominated profiles. The bottom boundary condition may either increase or decrease the active pressure depending on the hydraulic contrast. For some rainfall intensities, an intermediate layer thickness ratio produces a larger calculated active pressure than the corresponding homogeneous limits. These findings should be interpreted within the assumptions of one-dimensional vertical seepage, hydraulically and mechanically continuous layer interfaces, a smooth wall-back contact, and the adopted admissible three-dimensional failure mechanism. Full article

Cementitious sand and gravel (CSG) is commonly used in construction engineering; however, its mix proportion design is complex, and traditional physical experiments face limitations such as long cycles, high costs, and susceptibility to external factors when obtaining high-quality sample data. In this study, a foundational dataset was first acquired through physical experiments: 100 sets of CSG specimens with different mix proportions (cement content 40, 50, 60, 70 kg/m³; water-to-binder ratio 1.0, 1.2, 1.4; sand ratio 0.1, 0.2, 0.3, 0.4; fly ash content 20, 30, 40, 50 kg/m³) were prepared. After 28 days of standard curing, compressive strength and splitting tensile strength tests were conducted using a WAW-1000 electro-hydraulic servo universal testing machine, yielding 100 sets of real mechanical property data. The coefficients of variation for all test groups were below 10%, confirming the reliability and repeatability of the experimental data. On this basis, a data augmentation method based on Conditional Tabular Generative Adversarial Networks (CTGAN) is proposed. Through adversarial training between the generator and the discriminator, the model learns the multi-dimensional distribution characteristics of the original CSG data and generates 100 synthetic samples, which are then merged with the original data to expand the dataset to 200 samples. The quality of the synthetic data is evaluated using Wasserstein distance and correlation matrix heatmaps. Furthermore, a hybrid XGBoost–LSTM prediction model is proposed—XGBoost is used for feature construction to capture nonlinear interactions among mix proportion variables, and the constructed features are then fed into an LSTM network for sequential learning and regression prediction. The results show that the CTGAN-generated data are highly consistent with the original data in terms of kernel density distributions and variable correlations, with Wasserstein distance significantly superior to four comparative methods: Bootstrap, SMOTE, GaussianCopula, and TVAE. After augmentation, the XGBoost–LSTM model achieves a coefficient of determination (R²) of 0.9897 for compressive strength prediction (vs. 0.9793 before augmentation) and 0.9801 for splitting tensile strength (vs. 0.9882 before augmentation, a slight decrease). The mean absolute percentage errors (MAPE) are 4.49% and 4.11%, and the root mean square errors (RMSE) are 0.201 and 0.049, respectively; both error metrics are reduced compared with those before augmentation. Compared with baseline models including XGBoost, LSTM, Random Forest (RF), and Support Vector Regression (SVR), the XGBoost–LSTM model exhibits the best performance across all evaluation metrics, and Wilcoxon signed-rank tests confirm that the performance differences are statistically significant (p < 0.05). The proposed method of CTGAN-based data augmentation combined with the XGBoost-LSTM hybrid model provides an effective solution to the problem of insufficient CSG sample data and offers a reference for data enhancement and performance prediction of other small-sample materials. Full article

PFAS-laden fluid-filled porous media may be subjected to various mechanical loads which induce solid deformation and fluid flow and hence PFAS transport. This work employs a poroelasticity theory for unsaturated porous media to address the coupled solid deformation, fluid flow and PFAS transport in the vadose zone subjected to a mechanical load. The governing equation of the aqueous PFAS concentration is derived based on the PFAS mass balance that also considers the water content variation in the pores due to the solid deformation. Vertical PFAS transport in a finite soil layer under mechanical compression is studied using a finite difference method and the solutions of the pore fluid pressures and volumetric strain. Numerical results of the aqueous concentrations of perfluorooctane sulfonic (PFOS) in loamy sand and clay loam indicate that mechanical compression has pronounced effects on the spatial distribution of PFOS. In a loamy sand with relatively higher permeability, mechanical compression at the top drained surface leads to movement of PFOS from the topsoil to the surface thereby reducing the PFOS concentration in the topsoil especially at higher water saturations. The PFOS concentration in the subsoil, however, is not significantly influenced. The effect of mechanical compression on the PFOS concentration distribution in a clay loam can also be observed but is not as significant as in the loamy sand. The mechanical loading effects may be further explored to develop new technologies for PFAS risk assessment and remediation strategies. Full article

Soil quality is a critical factor impacting agricultural productivity and ecosystem functions. Accurate assessment of soil quality is crucial for sustainable agricultural development. Xinjiang is the primary cotton-producing region in China. Its unique geographical condition, characterized by two basins surrounded by three mountains, results in distinct climatic conditions, soil-forming factors, and soil physical and chemical properties across different cotton-growing areas. The spatial differentiation patterns of soil quality and their primary factors in cotton-growing regions of different river basins are not yet fully understood. This study focused on four typical cotton-growing areas of Xinjiang, China. A total of 1588 plow-layer soil samples were collected, and 21 indicators covering soil physical, chemical, and environmental properties were measured. By constructing a minimum data set (MDS) and comparing the performance of linear (LS) and non-linear (NLS) scoring functions, the effects of geographical environmental factors on the spatial distribution patterns of soil quality in cotton fields of different basins were analyzed. The results showed the MDS, composed of data on soil bulk density and the contents of organic matter, available iron, available zinc, nickel, sand, and silt, could replace the total data set. The NLS-MDS was identified as the optimal assessment model. Its Nash–Sutcliffe efficiency coefficient (E_f = 0.84) and coefficient of determination (R² = 0.70) were both higher than those of the linear model (E_f = 0.79, R² = 0.66). The study also revealed significant spatial heterogeneity in soil quality across different cotton-growing areas. The average soil quality index (SQI) in the Aksu River Basin (SQI_NLS-MDS = 0.53) and Xiaohaizi Basin (SQI_NLS-MDS = 0.50) was significantly higher than that in the Kuitun River Basin (SQI_NLS-MDS = 0.44) and Manas River Basin (SQI_NLS-MDS = 0.41). Random forest analysis demonstrated that the relative importance of topographic (digital elevation model) and climatic factors (annual mean temperature, annual mean precipitation) on SQI was higher than that of the vegetation factor (normalized difference vegetation index). The strong interaction between topographic and climatic factors was the primary driver of the spatial distribution of soil quality. This study confirms significant spatial heterogeneity of soil quality in cotton fields across different river basins in Southern and Northern Xinjiang, and identifies the synergistic interaction between topographic and climatic factors as the dominant driver of this heterogeneity in arid regions. These findings provide a scientific basis for implementing site-specific agricultural management in arid regions. Full article

The present paper reviews original data obtained by the authors from recent separate publications with additional unpublished data, specifically concerning the specific graphite morphology in Si/SiMo alloyed ductile irons (2.5–5.5% Si, 0.01–2.3% Mo) with alloying grade, cooling rate, and inoculation as influencing factors. Different formulas used for nodularity evaluation, including different forms of graphite participating in different proportion and two graphite shape factors: Roundness (RSF, involving maximum Ferret) and Sphericity (SSF, involving real perimeter). Slightly irregular spheroidal graphite morphology (Form V, ISO 945) characterized by RSF = 0.59–0.75 was found to be typical for Si and SiMo ductile irons in all of the test conditions, such as Si level (4.2–5.25% Si), Si–Mo system (4.1–4.8% Si + 1.6–2.3% Mo), mould type (green sand, resin sand, metal mould, external metallic chill), un-inoculation and inoculation, and inoculating element type. Increasing Si content negatively affects the compactness degree of spheroidal graphite particles (transition from VI to V form) and nodularity. Metal mould versus sand mould solidification of 4.5% Si ductile iron increases nodule count, graphite shape factors (RSF = 0.68–0.7 versus 0.59–0.64) and nodularity (67% to 76%). An external metallic chill in a resin sand mould promoted directional solidification and showed a nodularity decrease for increasing Si, for all the nodularity formulas and for the cooling rate range. Inoculating elements influenced the shape factors in thin wall castings, where Ca–Ba was better than simple Ca and Ca–RE could promote graphite at higher real perimeter and with lower shape factors. The correlation of the aspect of structure, graphite parameters and nodularity led to the conclusion that the nodularity formula according to ISO/WD 945-4-2015 (100% total area of Form VI and 90% of Form V), with SSF instead of RSF, appears to be better in High-Si/SiMo DI (especially for more than 4% Si), because it takes into account the presence of slightly irregular spheroidal graphite (with high real perimeter) at a high rate. Full article

Lithium-ion batteries are widely used in digital, power and energy storage fields due to their high capacity and high cycle life advantages. This paper systematically screens the formulation system and designs a high-efficiency production line that can effectively improve production efficiency, reduce production costs, and lower energy consumption per unit product. The produced nano-silicon-enhanced graphite anode material has excellent performance. The selection of silicon raw materials, types of solvents, types of dispersants, and grinding processes is studied to investigate the influence of these four factors on the wet grinding process for preparing nano-silicon. Finally, metal silicon obtained by air flow pulverization is selected as the raw material, isopropanol is used as the solvent, FA01 (carboxylic acid type) is used as the dispersant, and a two-stage wet grinding process is adopted to prepare the nano-silicon dispersion solution. Zirconia beads of 0.5 mm and 0.2 mm size are used as the grinding media for the first and second stages, respectively, with filling rates of 80% and 90%, respectively. The final prepared nano-silicon dispersion is stable in dispersion and has a narrow particle size distribution. The nano-silicon dispersion solution and the multi-walled carbon nanotube dispersion solution are mechanically ground and mixed using a sand mill. At the same time, the multi-walled carbon nanotubes are coated with the nano-silicon. Then, artificial graphite is added for compounding. Finally, through spray drying, the Si@MWCNTs@graphite (SMG) nano-silicon-enhanced graphite negative electrode material is prepared. The SMG nano-silicon-enhanced graphite negative electrode material with a silicon content of 2% has a first Coulomb efficiency of up to 84.32%. Full article

The Dingtao M2 Tomb, the largest, highest-specification, and best-preserved “Huangchangticou” tomb currently discovered in China, is of great significance for cultural relic conservation. During its dismantling and protection, extensive white filamentous fungal contamination was observed on the surface of sand-buried wood components. To clarify the dominant fungal species and its impact on wood cultural relics, the dominant fungus was isolated and purified from contaminated wood samples, and identified as Serpula himantioides (designated as DTW) via molecular and morphological methods. Systematic studies were conducted on DTW’s wood degradation capacity, cellulase activities, regulatory effects of Fe³⁺ and Ca²⁺ on cellulase activities, whole-genome characteristics, and sensitivity to fungistatic agents. The results indicated that DTW exhibited strong wood degradation ability: after 60 days of inoculation, the maximum force, elongation at break, and tensile strength of wood chips decreased significantly, by 88.0%, 54.6%, and 88.6%, respectively, compared with the control group. The cultural relic microenvironment colonized by strain DTW is rich in Fe³⁺ and Ca²⁺. Both ions can significantly suppress the activity and specific activity of cellulase from strain DTW at elevated concentrations. Whole-genome sequencing revealed that DTW had a genome size of 68,519,434 bp with a Guanine–Cytosine (GC) content of 44.01% and 18,373 genes; Carbohydrate-Active Enzyme (CAZy) and Cell Wall-Degrading Enzyme (CWDE) database annotations confirmed its strong plant cell wall degradation ability. Additionally, DTW was sensitive to screened green fungistatic agents, which effectively inhibited its growth. This study clarifies the species and wood degradation mechanism of the dominant fungus on Dingtao M2 Tomb’s sand-buried wood, providing theoretical and technical support for the protection of the tomb’s wood cultural relics. Full article

Offshore wind can diversify the Brazilian electricity matrix, but foundation design on the Ceará continental shelf must account for carbonate sands whose stiffness, crushability and stress-dependent response differ from those of quartz sands. This study contribution is the use of carbonate-sand parameters calibrated from consolidated-drained triaxial tests on Ceará-shelf sediments and the direct comparison of two sands with contrasting carbonate contents. The measured responses calibrated the Hardening Soil model in PLAXIS 2D, and the resulting parameters drove PLAXIS 3D simulations of monopiles with different diameters, embedment lengths and tower heights under monotonic lateral loading. The more calcareous sand showed higher frictional strength but lower stiffness—as a result, it mobilised larger mudline displacements, making the Serviceability Limit State more restrictive than the Ultimate Limit State. Pile diameter controlled lateral capacity, whereas reduced L/D lowered system stiffness and serviceability performance. Within the monotonic, homogeneous-profile scope adopted here, M3 (D = 9 m, L = 36 m, L/D = 4) gave the most favourable response for the medium-rated turbine class. The results provide screening-level comparative evidence, not a design-ready proof of feasibility. Full article

Alkali-activated fly ash geopolymers are promising low-carbon binders, but their performance depends strongly on mix proportion design. This study investigated the effects of water-to-binder ratio, sand content, and NaOH concentration on fly ash-based geopolymer using an L25(5⁶) orthogonal design. Flexural and compressive strengths were evaluated through range analysis and Analysis of Variance (ANOVA), while Random Forest was used as an exploratory tool for factor-response interpretation. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were conducted to relate mechanical behavior to microstructural evolution. The optimal combination within the tested levels was a water-to-binder ratio of 0.30, sand content of 40%, and NaOH concentration of 12 mol/L. The maximum flexural and compressive strengths reached 3.65 MPa and 17.98 MPa, respectively. NaOH concentration dominated flexural strength, whereas water-to-binder ratio primarily controlled compressive strength. Model benchmarking and cross-validation showed that the machine-learning results had limited generalization capability under the small-sample condition and should be interpreted as candidate screening rather than independent predictive validation. Microstructural analyses indicated that strength development was associated with matrix densification, aluminosilicate network reorganization, and amorphous geopolymeric gel formation. Full article

High ash andsss urea formaldehyde (UF) resin contents in particleboard sanding powder (SP) have restricted the effective resource utilization of SP and make it a hazardous biomass material for particleboard enterprises. To achieve high-value resource utilization of SP while addressing its hazardous disposal issues, different HCl concentration-oriented deashing pretreatments of SP coupled with fast pyrolysis was proposed for producing value-added pyrolytic sugar levoglucosan (LG) and high-quality pyrolytic char. The results show that H⁺ ions released from HCl solution could effectively remove structural ash, likely by disrupting the chemical linkages between the structural ash and lignocellulosic matrix. An amount of 2 mol/L HCl could achieve an over 95% removal rate of alkali and alkaline earth metals (AAEMs) in the ash while maintaining a low loss of polysaccharides. This considerably facilitated the glycosidic cleavage of cellulose into levoglucosan (LG), with the LG yield increasing from 2.18% of raw SP to 13.69% of 2 mol/L HCl deashed SP. Interestingly, it was found that HCl washing of SP facilitated the co-production of value-added platform chemical acetic acid via acid-catalyzed hydrolysis of acetyl groups in UF resin attached to the xylose unit, with the yield increasing from about 7% of raw SP to over 11% of HCl deashed one. Specifically, 2 mol/L HCl deashing pretreatment of SP significantly improved the quality of pyrolytic char with the ash content decreasing from 7.24% to 2.39% and fixed carbon content lifting from 54.08% to 76.04%, thus drastically improving the higher heating value (HHV) from 24.66% of raw SP-derived char to 30.05% of deashed SP-derived char. Moreover, the pyrolytic char CO₂ gasification reactivity increased from 0.027 min⁻¹ of raw SP-derived char to 0.034 min⁻¹ of that derived from 2 mol/L HCl deashed SP, approaching that of the widely used industrial charcoal fuel. Pyrolysis kinetic analysis indicates that deashing pretreatment of SP makes the formation of value-added platform chemicals and high-quality carbonaceous fuel proceed more easily at a lower activation energy (214.39 kJ·mol⁻¹) than that of raw SP (245.81 kJ·mol⁻¹). This study offers a novel approach for the synergistic production of value-added chemicals and high-quality carbonaceous fuel from biomass waste materials with high contents of ash and UF resin, providing a feasible strategy for the clean and high-value resource utilization of wood-based industrial residues. Full article

The low bearing capacity and high crushability of coral sand pose major challenges to island and reef foundation engineering. Herein, a newly developed non-isocyanate polyurethane was used to reinforce coral sand and the unconfined compressive behavior of polyurethane-reinforced coral sand was investigated based on an orthogonal experimental design. The effects of particle gradation, the mass ratio of polyurethane to sand and moisture content on strength, deformation, and energy evolution were analyzed. The results show that the highest uniaxial strength of 5.48 MPa was obtained for naturally graded coral sand with a polyurethane mass ratio of 30% under dry conditions. The moisture content was identified as the dominant factor affecting the strength, and elastic modulus of the reinforced samples. Increasing moisture content significantly reduced the crack initiation stress, dilation strength, peak strength and elastic modulus, while increasing Poisson’s ratio. In contrast, a higher polyurethane mass ratio improved the strength, stiffness and energy dissipation capacity, whereas particle gradation primarily influenced the crack initiation stress level. Under unconfined compression, the reinforced samples mainly exhibited ductile shear failure involving edge breakage, particle sliding, delamination and rupture of the cured polyurethane film. Microscopic observation indicated that the cured polyurethane worked as a surface film, an interparticle bridge and a pore-filling phase within the coral sand matrix. The enhancement in mechanical behavior was mainly associated with polymer bridging, pore filling, local interfacial adhesion and mechanical interlocking. Full article

An appropriate amount of active stone powder can effectively improve the performance of concrete and reduce the amount of cement. However, the doped clay in stone powder will have an adverse effect on the performance of concrete, and its contents need to be tested and strictly controlled. In this study, we have developed a new test method for evaluating the quality grade of sand powder using hyperspectral imaging. The collected hyperspectral data of stone powder are preprocessed by smoothing filtering and multiple scattering calibration (SG-MSC) to reduce the interference of background information. Competitive adaptive reweighted sampling (CARS) and the successive projections algorithm (SPA) have been used to extract the eigenvalues and display the characteristic band, respectively, and then to construct the eigenvector dataset of the spectral curve. Subsequently, a classification model combining CARS and the Support Vector Machine (SVM) algorithm is trained and applied to the quality grade identification of stone powder. Finally, a comparison has been made between the classification results of the Support Vector Machine (SVM) and K-Nearest Neighbor (KNN) models, which combined CARS and SPA, to construct a better evaluation model. Compared with the results of manual measurement, the proposed method demonstrates a high precision in the quality assessment of stone powder content in the actual production process. Full article

The growing demand for construction materials has intensified concerns regarding natural sand depletion and the accumulation of industrial waste. Among these wastes, oil-contaminated sand (OCS) generated from petroleum-related activities presents environmental challenges while also offering potential for beneficial reuse. Previous studies have reported that low OCS contents can enhance workability and improve mechanical properties, highlighting its potential as a sustainable construction material. This study investigates the feasibility of incorporating OCS as a partial replacement for natural sand in 3D concrete printing (3DCP). Three mixes containing 0%, 0.5%, and 1% OCS were evaluated in terms of flowability, setting behaviour, printability, rheological response, hydration behaviour, mechanical performance, anisotropic response, and microstructural characteristics. The results showed that OCS incorporation had only a limited influence on flowability, while both the initial and final setting times exhibited noticeable delays. The maximum printable layers reached from 19 for the control mixture to 22 and 26 layers for the 0.5% and 1% OCS mixes, respectively, accompanied by reduced settlement and structural deformation. Rheological analysis revealed higher static yield stress and structuration rates for the OCS-modified mixes, contributing to enhanced buildability and geometric stability. Hydration calorimetry showed comparable heat-flow behaviour between the control and OCS-modified mixes, suggesting only a limited influence of OCS on cement hydration kinetics. The incorporation of OCS improved the compressive strength of the printed mixes and reduced compressive anisotropy, while SEM observations revealed a denser and more homogeneous microstructure, particularly for the 0.5% OCS mix. Thus, the findings indicate that low-level incorporation of oil-contaminated sand is a viable strategy for improving the printability and performance of 3D-printed concrete, promoting the sustainable reuse of contaminated industrial waste. Full article

Constructed wetlands operated in plateau habitats may experience constrained biological treatment because low temperature, low atmospheric pressure, and low-carbon wastewater can jointly limit microbial metabolism. This 80-day pilot screening study evaluated three nonreplicated modular constructed wetland configurations (MCW1-MCW3) containing different sequences of zeolite, ceramsite, and quartz sand and planted with Veronica anagallis-aquatica. Each configuration consisted of one independent treatment train; therefore, the comparisons were interpreted as configuration-specific and exploratory rather than as statistically generalizable treatment effects. Pollutant-removal performance and microbial community succession were evaluated through repeated water-quality monitoring and 16S rRNA gene sequencing. MCW1 showed the highest observed mean NH₄⁺-N removal efficiency (88.6%), whereas MCW3 showed the highest observed mean TP and COD removal efficiencies (79.56% and 47.40%, respectively) and an NH₄⁺-N removal efficiency of 85.51%. TN removal by MCW3 remained limited at 20.49%, consistent with carbon limitation of denitrification. Under the naturally low-temperature plateau laboratory conditions, the observed COD reduction indicated partial mineralization or retention of organic pollution loads, potentially supported by substrate biofilms and cold-adapted microbial assemblages. Apparent module-contribution analysis suggested that zeolite contributed substantially to NH₄⁺-N reduction, whereas ceramsite contributed to TP and COD removal under the tested sequences. Because plant biomass and tissue nutrient contents were not measured, nitrogen and phosphorus removal could not be attributed quantitatively to hydrophyte uptake. Overall, substrate sequence influenced pollutant-removal patterns and microbial community assembly, providing preliminary evidence for habitat-adapted optimization of modular constructed wetlands for plateau domestic wastewater. Full article

Construction and demolition waste valorization as recycled aggregates remains largely underdeveloped in North African urban contexts. This study presents the first normatively referenced characterization of recycled aggregates from ten sites in Fez, Morocco, combined with experimental C25/30 concrete formulation using the Dreux-Gorisse method. Physical, mechanical, and chemical analyses reveal high water absorption (9.98 ± 0.94%), low particle density (2197 kg/m³), sub-standard sand equivalent (39.4%), and elevated methylene blue (3.06 g/kg), all governed by attached cementitious mortar content. Principal component analysis identifies three groups: Cluster A (E2, E6, E8), directly valorizable for structural use; Cluster B (E3, E4, E7, E10), requiring fine-fraction removal (<80 µm) prior to concrete incorporation; and an intermediate group (E1, E5, E9), suitable for non-structural applications. Concrete mixes from a composite blend of all ten samples were experimentally validated on cylindrical specimens. At 25% substitution, the 28-day compressive strength reaches 22–28 MPa, achieving marginal C25/30 compliance when superplasticizer and pre-wetting correction (9.98 L/100 kg recycled aggregate) are applied; substitution at 50% and above does not meet structural requirements (18–24 MPa). Durability assessments confirm increasing carbonation depth (7–11 mm at 25%) and moderate-to-high chloride permeability, underscoring the need for source-selective sampling and pre-treatment in urban construction and demolition waste valorization programs, particularly in North African and Maghreb contexts where construction materials and building practices are broadly similar and demolition waste is typically processed without prior sorting. Full article