This study developed a novel geopolymer (RM-SGP) using industrial solid wastes red mud and slag activated by sodium silicate, aiming to remediate composite heavy metal contaminated soil. The effects of aluminosilicate component dosage, alkali equivalent, and heavy metal concentration on the unconfined compressive strength (UCS), toxicity leaching characteristics, resistivity, pH, and electrical conductivity (EC) of RM-SGP solidified composite heavy metal contaminated soil were systematically investigated. Additionally, the chemical composition and microstructural characteristics of solidified soil were analyzed using XRD, FTIR, SEM, and NMR tests to elucidate the solidification mechanisms. The results demonstrated that RM-SGP exhibited excellent solidification efficacy for composite heavy metal contaminated soil. Optimal performance occurred at 15 % aluminosilicate component dosage and 16 % alkali equivalent, achieving UCS >350 kPa and compliant heavy metal leaching (excluding Cd in high-concentration groups). Acid/alkaline leaching tests revealed distinct metal behaviors: Cu/Cd decreased progressively, while Pb initially declined then rebounded. Microstructural analysis indicated that RM-SGP generated abundant hydration products (e.g., C-A-S-H, N-A-S-H gels), which acted as cementitious substances wrapping soil particles and filling and connecting pores, thereby increasing the soil's compactness and improving the solidification effect. Furthermore, heavy metal ions were solidified through adsorption, encapsulation, precipitation, ion exchange, and covalent bond et al., transforming their active states into less bioavailable forms, proving novel insights into the remediation of composite heavy metal contaminated soils and the resource utilization of industrial solid wastes.

In this study, carbide slag, fly ash, cement, and sodium sulfate were used to stabilize silt from the Yellow River Alluvial Plain. An orthogonal test was conducted to evaluate the optimal mix design for soil stabilization. The mechanical properties, hydration products, and microstructure of the stabilized silt were examined. The effects of stabilizer concentration, compaction, and moisture content on the mechanical properties were investigated. Based on mechanical performance, the optimal stabilizer mix was found to consist of 30% cement, 13.6% carbide slag, 54.4% fly ash, and 2% sodium sulfate. The results indicated that the California Bearing Ratio (CBR), unconfined compressive strength, and splitting tensile strength of the stabilized silt increased with higher stabilizer dosage and compaction degree. In the early stages, the hydration products of the stabilized silt were primarily calcium hydroxide, ettringite, and C-S-H, which exhibited a loose structure. Over time, the microstructure densified, and more crystalline C-S-H was formed. This study provides valuable insights into the use of industrial by-products for soil stabilization, offering a sustainable and cost-effective solution to improve the strength and stability of silt in construction projects.

Gravel-bearing sandstone reservoirs represent a significant type of reservoir in oil and gas exploration. Due to the difference of the spatial random distribution the content and the shape of the gravel particles, these reservoirs exhibit complex mechanical properties and failure modes. In this study, a numerical model of gravel-bearing sandstone was developed by using the Finite Element Method (FEM) and were verified by the actual indoor experimental data. The effect of the gravel particle sizes, gravel content, and gravel types on the compressive peak strength and microcrack evolution processes are further analyzed. The results reveal that cracks initiate within the sandstone matrix surrounding the gravel and propagate through the gravel with continued loading. The primary factors governing the stability of gravel-bearing sandstone are the gravel radius and content. The variation in gravel penetration rate is synchronized with the changes in peak strength. By embedding gravel particles of different shapes into the model, it is observed that the peak compressive strength of round gravel is comparable to that of elliptical gravel, with both exhibiting higher peak strengths than angular gravel. Regression models demonstrate that the tensile strength difference between the gravel and the sandstone matrix is a critical parameter influencing gravel penetration. Confining pressure has a relatively minor effect on the elastic modulus, while its impact on peak compressive strength is significantly more pronounced.

Mastering the mechanical properties of frozen soil under complex stress states in cold regions and establishing accurate constitutive models to predict the nonlinear stress-strain relationship of the soil under multi-factor coupling are key to ensuring the stability and safety of engineering projects. In this study, true triaxial tests were conducted on roadbed peat soil in seasonally frozen regions under different temperatures, confining pressures, and b-values. Based on analysis of the deviatoric stress-major principal strain curve, the variation patterns of the intermediate principal stress, volumetric strain and minor principal strain deformation characteristics, and anisotropy of deformation, as well as verification of the failure point strength criterion, an intelligent constitutive model that describes the soil's stress-strain behavior was established using the Transformer network, integrated with prior information, and the robustness and generalization ability of the model were evaluated. The results indicate that the deviatoric stress is positively correlated with the confining pressure and the b-value, and it is negatively correlated with the freezing temperature. The variation in the intermediate principal stress exhibits a significant nonlinear growth characteristic. The soil exhibits expansion deformation in the direction of the minor principal stress, and the volumetric strain exhibits shear shrinkage. The anisotropy of the specimen induced by stress is negatively correlated with temperature and positively correlated with the bvalue. Three strength criteria were used to validate the failure point of the sample, and it was found that the spatially mobilized plane strength criterion is the most suitable for describing the failure behavior of frozen peat soil. A path-dependent physics-informed Transformer model that considers the physical constraints and stress paths was established. This model can effectively predict the stress-strain characteristics of soil under different working conditions. The prediction correlation of the model under the Markov chain Monte Carlo strategy was used as an evaluation metric for the original model's robustness, and the analysis results demonstrate that the improved model has good robustness. The validation dataset was input to the trained model, and it was found that the model still exhibits a good prediction accuracy, demonstrating its strong generalization ability. The research results provide a deeper understanding of the mechanical properties of frozen peat soil under true triaxial stress states, and the established intelligent constitutive model provides theoretical support for preventing engineering disasters and for early disaster warning.

This study investigates the effects of incorporating date palm wood powder (DPWP) on the thermal, physical, and mechanical properties of lightweight fired earth bricks made from clay and dune sand. DPWP was added in varying proportions (0 %, 5 %, 8 %, 10 %, 12 %, and 15 % by weight of the soil matrix) to evaluate its influence on brick performance, particularly in terms of thermal insulation. Experimental results revealed that adding DPWP significantly reduced the thermal conductivity of the bricks, achieving a maximum reduction of 56.41 %. However, the inclusion of DPWP negatively impacted the physical and mechanical properties of the samples. Among the tested bricks, those with 8 % and 10 % DPWP achieved a desirable balance, maintaining satisfactory mechanical strength within acceptable standards while achieving thermal conductivity values of 0.333 and 0.279 W/m & sdot;K, representing reductions of 37.29 % and 47.46 %, respectively. To further validate these findings, prototypes of the DPWP-enhanced fired bricks and commercial bricks were constructed and tested under real environmental conditions during both summer and winter seasons, over a continuous 12-h daily period. The DPWP-enhanced prototypes demonstrated superior thermal performance, with temperature differences reaching up to 3 degrees C compared to the commercial bricks. These findings highlight the potential of DPWP as a sustainable additive for improving the thermal insulation properties of fired earth bricks, thereby promoting eco-friendly and energy-efficient building materials for sustainable construction practices.

Freeze-thaw cycles pose a serious threat to the protection and preservation of earthen sites. To investigate the effects of freeze-thaw cycles on the shear strength and permeability of site soil, this study took artificially prepared site soil as the research object. Through triaxial shear tests and permeability tests, the strength and permeability characteristics of site soil under different sticky rice slurry content, sticky rice slurry density and freeze-thaw cycles were analyzed. In addition, the mineral composition, chemical structure, and microstructural characteristics of the samples were investigated by combining X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) tests. The results showed that the addition of sticky rice slurry could increase the shear strength and decrease the permeability coefficient of the soil, while the opposite effect was exhibited after freeze-thaw cycle. The optimum ratio of loess to sticky rice slurry was 95:5, and the optimum density of sticky rice slurry was 1.04 g/cm3. The addition of sticky rice slurry and the increase in the number of freeze-thaw cycles did not significantly change the mineral composition of the soil. The SEM results showed that the morphology and arrangement of soil particles became complex after freeze-thaw cycle, the inter-particle connections became loose, and the pore morphology became irregular. The surface porosity of the soil increased, and the proportion of large and medium pores increased. The directionality of the pores was enhanced, and the complexity of the pores increased. The pore arrangement became relatively stable after 15 freeze-thaw cycles. These findings can provide a reference for the restoration of ancient sites in loess areas.

The lack of global standardization in the testing methods for Stabilized Rammed Earth (SRE) hinders progress in advancing knowledge of this sustainable construction technique. This review compiles research from the last four years on SRE, focusing on manufacturing parameters, curing conditions, chemical stabilizer kinds, stabilizer dosage, testing methods, and mechanical and durability properties. Based on this analysis, a methodology is proposed to define and standardize SRE manufacturing parameters, curing, and testing conditions. The proposed methodology suggests that soil particle size distribution should be optimized to enhance mechanical strength and durability while reducing stabilizer dosage. The selection and dosage of stabilizers should be determined based on soil characteristics and environmental considerations. The standard proctor test is recommended for assessing manufacturing conditions, while curing should be performed by wrapping samples in plastic at laboratory temperature. Unconfined Compressive Strength is identified as the most relevant mechanical test and should be conducted at 7, 28, and 90 days. For durability assessment, erosion testing and exposure to liquid water are recommended at 28 days. This methodology represents one of the first steps toward the standardization of SRE testing methods, which must be accepted and adopted by researchers and practitioners. By implementing this methodology, comparable results across studies could be achieved, facilitating further research and collaboration among researchers. Such efforts would contribute to enhancing the available knowledge to improve the material's performance and further promote SRE as a sustainable construction technique.

The paper investigates the effect of curing conditions on the properties of laterite soil-based geopolymer cement. In the experimental testing, calcined laterite soil was used as a solid precursor in the preparation of geopolymer cement. Standard size prismatic geopolymer specimens were prepared and subjected to four curing methods, including open air curing and courses of combined open-air curing and oven curing. The prisms were tested at 3, 7, and 28 days to determine the effect of curing methods on the flexural and compressive strengths. The crushed prisms were further pulverised and analysed to investigate the microstructure, elemental composition, mineralogical phases, chemical bonding, and thermal behaviour. The findings showed that the highest strength at 28 days was obtained with the air curing method. However, the curing methods involving an oven curing course resulted in the highest early strength at 3(early strength) and 7 days.

The infiltration and degradation of domestic contaminants have a substantial influence on the mechanical properties of soil. Sucrose is one of the oligosaccharide contaminants with high content and is prone to degradation in domestic-source contaminants. In this study, a series of tests were conducted to investigate the changes in the mechanical properties of clayey soil during the sucrose degradation process. First, in different concentrations of sucrose-contaminated soil, the organic matter content during the sucrose degradation process was measured to analyze its degradation characteristics. During the degradation process, the unconfined compressive strength and compression coefficient of the soil were measured to analyze the changes in its mechanical properties. Finally, the changes in the permeability coefficient and microstructure of the soil were analyzed in depth. The findings indicated that the degradation of sucrose and the associated alterations in the mechanical properties of contaminated soil were concentration-dependent. The effect mechanism involved the formation of organic-clay flocs during the early stages of degradation and the alkaline oxides' dissolution in the later stages. These findings contribute to a deeper understanding of the impact of domestic-source pollution on soil and provide references for the reinforcement of contaminated soil.

In response to the problems of poor mechanical ductility and high hydrophilicity of natural polysaccharide films, we propose to introduce rubber material (carboxystyrene styrene-butadiene latex, XSBR) into natural polysaccharides (sodium alginate, SA) to enhance the mechanical properties of SA and reduce its hydrophilicity. In addition, dispersing ZnO in SA through the mediating effect of XSBR can further reduce its hydrophilicity and endow the composite film with antibacterial activity. The tensile strength and strain of the composite film reached 16.1 MPa and 267.3 %, respectively (strain increased by 74 times compared to SA films). The biomimetic design of the ZnO uniformly distributed on the film's surface mimics the tiny synapses on the surface of a lotus leaf, further improving the film's hydrophobic and waterproof properties, with its water contact angle increasing from 68.7 degrees to 97.6 degrees. Besides, the composite film exhibits good light transmission, barrier, antimicrobial, and antioxidant activity. The composite film was effective in extending strawberry freshness up to 9 days. More importantly, indoor-outdoor soil degradation studies proved that the composite film is degradable. This work provides a possible solution for developing durable, hydrophobic, and biodegradable biomass films to replace petroleum-based plastic films.