The interface between geotextile and geomaterials plays a crucial role in the performance of various geotechnical structures. Soil-geotextile interfaces often suffer reduced performance under environmental stressors such as rainfall and cyclic loading, limiting the reliability of geotechnical structures. This study examines the influence of gravel content (Gc), compaction degree (Cd), and rainfall duration (Rd) on the mobilized shear strength at the silty clay-gravel mixture (SCGM)- geotextile interface through a comprehensive series of direct shear tests under both static and cyclic loadings. A novel approach using Polyurethane Foam Adhesive (PFA) injection is introduced to enhance the interface behavior. The results reveal that increasing Gc from 0 % to 70 % leads to a 35-70 % improvement in mobilized shear strength and friction angle, while cohesion decreases by 15 %-60 %, depending on Cd. A higher Cd further boosts shear strength by 6 %- 70 %, influenced by Gc and normal stress levels. Under cyclic loading, increasing displacement amplitude reduces shear stiffness (K), while having minimal impact on the damping ratio (D); K and D appear unaffected by the number of cycles in non-injected samples. Rainfall reduces mobilized shear strength by 8 %-25 %, depending on the normal stress, with a 47 % drop in friction angle and a 24 % increase in cohesion after 120 minutes of rainfall exposure. In contrast, PFA-injected samples exhibit a marked increase in mobilized shear strength under both dry and wet conditions, primarily attributed to enhanced cohesion. Notably, PFA treatment proves particularly effective in maintaining higher shear strength and stiffness in rainfall-affected interfaces, demonstrating its potential in improving geotextile-soil interaction under challenging environmental conditions.

Alkali-activated materials have gained increasing popularity in the field of soil barrier materials due to their high strength and low environmental impact. However, barrier materials made from alkali-activated materials still suffer from long setting times and poor barrier performance in acidic, alkaline, and saline environments, which hinders the sustainable development of green alkali-activated materials. Herein, coconut shell biochar, sodium silicate-based adhesives, and polyether polyol/polypropylene polymers were used for multi-stage material modification. The modified materials were evaluated for barrier performance, rapid formation, and resistance to acidic, alkaline, and saline environments, using metrics such as compressive strength, permeability, mass loss, and VOC diffusion efficiency. The results indicated that adhesive modification reduced the material's setting time from 72 to 12 h. Polymer modification improved resistance to corrosion by 15-20%. The biochar-containing multi-stage modified materials achieved VOC diffusion barrier efficiency of over 99% in both normal and corrosive conditions. These improvements are attributed to the adhesive accelerating calcium silicate hydration and forming strength-enhancing compounds, the polymer providing corrosion resistance, and biochar enhancing the volatile organic compounds (VOC) barrier properties. The combined modification yielded a highly effective multi-stage green barrier material suitable for rapid barrier formation and corrosion protection. These findings contribute to evaluating multi-level modified barrier materials' effectiveness and potential benefits in this field and provide new insights for the development of modified, green, and efficient alkali-activated barrier materials, promoting the green and sustainable development of soil pollution control technologies.

Significant quantities of bark are generated during wood processing, with the majority being utilized for energy production and soil enhancement. This study investigated the influence of bark particle size and resin type (urea-formaldehyde (UF) and melamine-urea-formaldehyde (MUF)) on the properties of particleboards made from spruce and pine bark. Board samples were fabricated using different bark particle sizes (2 to 5 mm and 5 to 8 mm) and varying adhesive contents (5% and 7%) for both UF and MUF adhesives. Reference particleboards were manufactured using industrial wood particles with the same UF and MUF adhesive contents. The spruce bark consistently outperformed pine bark across most investigated properties. Board samples fabricated from spruce bark particles exhibited higher internal bond (IB) strength and modulus of rupture (MOR), as well as enhanced resistance to water absorption (WA) and thickness swelling (TS), particularly when bonded with urea-formaldehyde (UF) adhesive. Specifically, boards composed of spruce bark, using a combination of bark particle sizes, UF adhesive, and 7% adhesive content, exhibited superior performance in IB strength, water resistance, and modulus of elasticity.

The widespread distribution of saline soil in the severe cold regions of northwest China has caused dual damage to concrete structures, including freeze-thaw cycles and sulfate erosion, seriously threatening the adhesive performance of interface agents. To solve the problem, the evolution law of the interface adhesive performance of the interface agent in standard curing, natural exposure, freeze-thaw cycle and sulfate attack environment was studied by modified acrylate lotion. The results indicated that environmental factors have a significant impact on interface strength, with the destructive effect of freeze-thaw cycles being the most prominent. The modified acrylate lotion improved the interface performance through a triple action mechanism: (1) penetrated the matrix to form a pore bolt structure, enhancing the mechanical anchoring effect; (2) The complexation of carboxylic acid carbonyl groups with Ca2+ enhanced the chemical adhesive strength; (3) Its flexibility and filling effect reduced freezing pressure, refined pores, and effectively inhibited water migration and ion erosion. The study further revealed the key mechanisms of interface pore coarsening, and pore plug structure degradation in freezethaw environments, providing new solutions and theoretical support for concrete repair in cold regions.

The mechanical properties and envelope curve predictions of polyurethane-improved calcareous sand are significantly influenced by the magnitude and direction of principal stress. This study conducted a series of directional shearing tests with varying polyurethane contents (c = 2.5%, 5%, and 7.5%), stress Lode angles (theta sigma = -19.1 degrees, 0 degrees, 19.1 degrees, and 30 degrees), and major principal stress angles (alpha = 0 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees) to investigate the strength and non-coaxial characteristics of calcareous sand improved by polyurethane foam adhesive (PFA). Key findings revealed that failure strength varied significantly with the major principal stress axis direction, initially decreasing to a minimum at alpha = 45 degrees before increasing, with a 30% decrease and 25% increase observed at c = 5%. Non-coaxial characteristics between strain increment and stress directions became more pronounced, with angles varying up to 15 degrees. Increasing polyurethane content from 2.5% to 7.5% enhanced sample strength by 20% at theta sigma = -19.1 degrees and alpha = 60 degrees. A generalized linear strength theory in the pi-plane accurately described strength envelope variations, while a modified Lade criterion, incorporating polymer content, effectively predicted multiaxial strength characteristics with less than 10% deviation from experimental results. These contributions provide quantitative insights into failure strength and non-coaxial behavior, introduce a robust strength prediction framework, and enhance multiaxial strength prediction accuracy, advancing the understanding of polyurethane-improved calcareous sand for engineering applications.

The sharp morphological features of lunar dust particles generate significant elastic-plastic contact forces and deformations upon contact with material surfaces, which considerably affect the mechanical properties of lunar dust particles, including their contact, collision, adhesion, transport, and wear characteristics. Despite these severe effects, valid models considering the contact characteristics of typical sharp-featured lunar dust particles are currently lacking. This study proposes an elastic-plastic contact model for nonrotationally symmetric lunar dust particles showing typical sharp features. Detailed derivations of the expressions for various physical responses observed when lunar dust particles establish normal contacts with elastic and elastic-plastic half-spaces under adhesive conditions are also provided. These include derivations for elastic forces, elastic-plastic forces, contact areas, pull-off forces, residual displacements, and plastic deformation areas. Furthermore, the tangential pull-off force during the tangential loading of lunar dust particles is derived, and the tangential contact characteristics are explored. Comparisons of the results of the proposed model with those of previous experiments reveal that the proposed model shows errors of only 6.06 % and 1.03 % in the maximum indentation depth and residual displacement, respectively. These errors are substantially lower than those of conventional spherical models (60.30 % and 60.13 %, respectively), confirming the superior accuracy of the proposed model. Furthermore, the discrete element method is employed to analyze the effects of normal and tangential contacts, dynamic characteristics, and plastic deformations on the considered lunar dust particles. The results are then compared with those of existing contact models. They reveal that maximum elastic-plastic forces under normal contact conditions are positively correlated with the initial velocity but negatively correlated with the lateral angle. Furthermore, the tangential pull-off force is positively correlated with the normal force and surface energy. In addition, the contact duration of lunar dust particles is positively correlated with their initial velocities, while the residual displacement is negatively correlation. For instance, as the initial velocity increases from 10 to 50 m/s, the maximum elastic-plastic force increases from 37.64 to 321.72 mN. Comparisons of the proposed model with other contact models reveal that the maximum elastic-plastic force of the elastic-plastic triangular pyramid model is only 14.93 % that of the cylindrical model, 34.23 % that of the spherical model, and 76.27 % that of the conical model, indicating significant reductions in the maximum elastic-plastic force owing to the plastic deformations of particles with typical sharp features. Overall, the results of this study offer crucial insights into the mechanical characteristics of nonspherical lunar dust particles under various contact conditions, such as elastic-plastic and adhesive contacts, and can guide in situ resource utilization on the lunar surface and for craft landings.

The paper reports new hydrogels based on quaternary ammonium salts of chitosan designed as biocidal products. The chitosan derivative was crosslinked with salicylaldehyde via reversible imine bonds and supramolecular selfassemble to give dynamic hydrogels which respond to environmental stimuli. The crosslinking mechanism was demonstrated by 1H NMR and FTIR spectroscopy, and X-ray diffraction and polarized light microscopy. The hydrogel nature, self-healing and thixotropy were proved by rheological investigation and visual observation, and their morphology was assessed by scanning electron microscopy. The relevant properties for application as biocidal products, such as swelling, dissolution, bioadhesiveness, antimicrobial activity and ex-vivo hemocompatibility and in vivo local toxicity and biocompatibility on experimental mice were measured and analyzed in relationship with the imination degree and the influence of each component. It was found that the hydrogels are superabsorbent, have good adhesivity to skin and various surfaces and antimicrobial activity against relevant gram-positive and gram-negative bacteria, while being hemocompatible and biocompatible. Besides, the hydrogels are easily biodegraded in soil. All these properties recommend the studied hydrogels as ecofriendly biocidal agents for living tissues and surfaces, but also open the perspectives of their use as platform for in vivo applications in tissue engineering, wound healing, or drug delivery systems.

The market of epoxy resin-based adhesives is constantly growing in the automotive, electronics, and healthcare industries thanks to their unique features such as high bonding strength, durability, and corrosion resistance. In this work, alternative sustainable vitrimer adhesives, containing from 20 to 50 wt% of lignin microparticles, were prepared from epoxidized linseed oil (ELO) and a boronic ester dithiol crosslinker (DBEDT), in the absence of solvents and catalysts. The addition of unmodified commercial Kraft lignin to the composites directly influences their thermal and mechanical properties and determines their bonding capacity between several adherent substrates, also affecting the rewelding potential. The lignin-vitrimer composites and the corresponding neat vitrimer matrix exhibited values of lap shear strengths in the range of 9 to 17 MPa, when tested as adhesives with aluminum, stainless steel, and wood specimens, and good to excellent rewelding capability. The amount of lignin microparticles influences the balance between cohesive and adhesive forces during the separation of the adhered aluminum surfaces and the eventual joint failure. In the case of the composites with 20 wt% of lignin, lap shear strength remains constant even after four cycles of rebonding via compression molding, indicating that the best rewelding performance is associated with previous cohesive failure when the adhesive remains on both aluminum sheets' surfaces. In addition, the adhesion was preserved for 83 % of the initial value after 24 h immersed in water. Importantly, biodegradability in both soil and seawater was enhanced by the presence of the lignin filler. In summary, the simple preparation strategy of bio-based vitrimer composites coming from two natural sources could pave the way to green alternatives for industrial applications, such as epoxy-based adhesives.

Robust ionic conductive sensors with biocompatibility play a great role in flexible electronics and human-machine interfacing. However, the simultaneous attainment of ionic conductive sensors with high ionic conductivity, outstanding mechanical properties, ambient stability, and skin adhesiveness remains a major challenge. Herein, inspired by root-soil interlocked micro/nanostructure, a fiber-reinforced hybrid hydrogel for strain sensor is developed by infiltrating a polyacrylamide (PAM)-grafted sodium alginate (SA) hydrogel precursor into thermoplastic polyurethane (TPU) fibrous membranes and introducing glycerol (GL) and CaCl2. Alongside remarkable mechanical properties (stress up to 5.93 MPa and strain up to 658.32%), the obtained TPU hybrid hydrogel also possesses high ionic conductivity (1.93 S m(-1)). As a strain sensor, the hybrid hydrogel exhibits excellent sensitivity (gauge factor = 1.95), a large response range (0-658.32%), remarkable cycling stability, and good adhesiveness, suitable for monitoring various human activities, especially pulse monitoring and speech recognition. Moreover, the inclusion of CaCl2 and glycerol provides the hybrid hydrogel with exceptional water-retention and antifreezing properties, enabling practical usage in severe environments. This work provides effective ideas for the design of ionic conductive sensors with high strength, high sensitivity, adhesiveness, and ambient stability, which have potential applications in multifunctional and wearable electronics.