A significant amount of open-pit-mine broken sandstone (OMBS) is produced during open-pit mining. The mechanical strength of the loose sandstone is critical for ensuring dump slope stability and sustainable mine construction. This study investigates the modification of OMBS using artemisia sphaerocephala krasch (ASK) gum to enhance its engineering properties. Unconfined compressive strength, shear strength and permeability tests were conducted to quantitatively analyze the modification effect. And the stability was evaluated using FLAC3D simulation methods. The modification mechanism was characterized through SEM, FT-IR, XRD. The results demonstrated that the addition of 2 % ASK gum significantly improved OMBS mechanical performance and reduced permeability. Meanwhile, the failure mode of OMBS changed with the ASK gum content increasing. The simulation result indicated the stability of modified dump slope was better under the drying-wetting cycle. From the perspective of microstructure and chemical characteristics, the addition of ASK gum created new hydrogen bonds through intermolecular interactions with the hydrophilic groups between OMBS particles and formed a dense and stable structure through three reinforcement modes: surface encapsulation, pore filling, and bonding connection. This study provides a new idea for resource saving and environmentally friendly mining area development.

Mulching films serve various functions, such as temperature regulation, moisture retention, and weed suppression. They can substantially increase crop yields and are widely adopted in agricultural practices. However, the use of traditional plastic mulch films is limited by their difficult recycling processes and poor biodegradability, leading to soil contamination and negatively affecting crop growth. Consequently, eco-friendly alternatives are gaining attention as replacements for conventional petroleum-based films in agricultural applications. Enhancing the performance of these eco-friendly films remains a crucial challenge. Traditional polyvinyl alcohol (PVA) films have inherent limitations, including low mechanical strength and poor water resistance. In this work, a PVA/sodium alginate (SA)/glycerol (GLY)/glutaraldehyde (GA) film was prepared that is biodegradable, demonstrates superior mechanical properties, and offers exceptional transparency through glutaraldehyde crosslinking. The impact of GA on films was examined using characterization techniques. The findings revealed that the composite film has a uniform, compact surface with no observable holes or aggregation. The mechanical performance and water vapor barrier properties (WVP) of the film were significantly enhanced after GA crosslinking. The tensile strength and elongation at the break of the PVA/SA/GLY/GA film reached 33.73 MPa and 362.89%, respectively. This work offers a straightforward approach to the development of sustainable agricultural materials.

The soil construction materials cured with biopolymers are gradually being recognized and widely used in engineering areas, such as roadbeds or foundation fills. The strength of biopolymer-solidified soils (BSS) is easily influenced by the change of internal residual moisture content (RMC), however, the quantitative relationship between them remains unclear. Xanthan gum, as a representative of biopolymer, was used in this study to enhance the mechanical properties of silty sand dredged from the Yellow River under different initial water contents and curing temperatures. The unconfined compressive strength (UCS), curing time, water stability and microscopic properties of BSS were investigated via a series of indoor experiments. Results show that the proposed method for quantitatively evaluating the BSS strength using different RMC values was found to be workable compared to that of the traditional cement-treated method under different curing ages. The curing time required for BSS to reach a certain target strength, i.e. 2900 kPa, is reduced to 9.3 h at a higher curing temperature of 90 degrees C. Moreover, BSS exhibits the self-healing properties of strength recovery after re-temperature drying, with a strength recovery ratio above 45%. The control raw soil samples completely disintegrate in water within 10 s, and even lower xanthan gum biopolymer dosages, such as 0.5%, improved stability in water by reducing permeability by sealing the internal voids of the soil. SEM results indicate that the initial water content and curing temperature mainly affect the distribution of effective xanthan gum linkages, and thus significantly improve the strength and water stability of BSS. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Microbially Induced Magnesium Carbonate Precipitation (MIMP) technology provides an innovative method for solidifying and stabilizing heavy metal-contaminated soils. However, the mechanical strength and microstructure of the soil following remediation require further investigation. This study evaluates the mechanical properties of zinc-contaminated soil solidified using MIMP technology under varying zinc ion concentrations, cementing solution concentrations, and curing times. Unconfined compressive strength tests, carbonate production tests, and microscopic analyses are employed to assess microstructural changes. The results indicate that MIMP enhances the unconfined compressive strength of red clay, with significantly higher strength observed in samples without zinc contamination than those with zinc contamination. The maximum unconfined compressive strength is achieved at a cementing solution concentration of 1.25 mol/L and a curing time of 15 days, conditions under which the production of magnesium carbonate also peaks. As the zinc ion concentration increases, the unconfined compressive strength of the samples gradually decrease, accompanied by a reduction in magnesium carbonate production. With longer curing times, the unconfined compressive strength increases while the amount of magnesium carbonate rises and stabilizes. Microscopic analysis reveals that MIMP treatment fills internal pores, reducing their number and enhancing the bonding strength between soil particles. The primary mineral composition consists predominantly of hydromagnesite and magnesium carbonate.

Recycling paper sludge waste (PSW) into inexpensive sheets for applications in household interiors, construction, and footwear is a sustainable approach to resource utilisation and pollution reduction. A flexible recycled sheet (FRS) in board form was developed using cellulosic-based PSW from the paper industry and a styrene-butadiene rubber (SBR) binder. Various SBR concentrations were tested to determine the optimal amount for superior mechanical properties. The produced FRS was characterised using Fourier transform infrared spectroscopy, thermogravimetric analysis, high-resolution scanning electron microscopy, and energy-dispersive X-ray spectroscopy. FRS made with 1000 g of PSW:300 ml of SBR exhibited enhanced mechanical properties, including tensile strength (62.32 +/- 0.51 MPa), elongation at break (51.99 +/- 0.94%), tearing strength (17.76 +/- 0.45 N/mm), and flexibility (6.98 +/- 0.24%). A biodegradation study, conducted per ASTM D 5988-03, assessed environmental impact by measuring carbon-to-CO2 conversion in soil over 90 days. All FRS samples showed similar degradation within the first 30 days, with FRS 5 degrading significantly faster thereafter due to its higher cellulose and hemicellulose content. This highlights the potential of PSW-based FRS as an environmentally friendly and mechanically robust material for diverse applications.

The massive accumulation of waste PET plastic (WP) and coal gangue (CG) would induce a series of environmental problems such as causing soil and water pollution. For reducing the environmental pollution induced by these two wastes, this study attempts to utilize the combination of WP and CG into cement-based materials. Cement mortars incorporated with fine waste plastic (FWP) replacing part of sand and concrete blended with CG and coarse waste plastic (CWP) as part of coarse aggregate were prepared and their work-ability, mechanical strengths, dynamic elastic modulus (DEM), chloride ion permeability, hydration and microstructures were systematically investigated. In addition, metakaolin (MK) as a kind of active admixture was added into mortar or concrete and its effect of MK on the property of cement mortar or concrete was evaluated. The results show that the strengths of cement mortars containing various level of FWP decrease with increase of FWP and CG level. The mechanical strengths of concrete containing MK and 25-100 % CG and CWP are appropriate at different ages. Although the strengths of concrete blended with MK and wastes aggregate are lower than that of concrete without wastes, it is obviously higher than that of concrete only containing wastes but not MK. Its slump of fresh concrete significantly declines with CWP and CG contents growth. The coulomb electric flux and chloride migration coefficient of concrete at 28d generally increase with CG and CWP level, which indicates a declined tendency of resistance to chloride ion penetration. Its DEM for concrete measured with ultrasonic testing method slightly decrease with rise of CG and CWP content (25-100 %) and can give a basic prediction of strengths and chloride ion permeability. Hydration and microstructures tests including TG/DTA, MIP and SEM/EDS demonstrate that the pozzolanic reaction of MK can result in more gels generated and strengthen the ITZ between WP or CG and cement paste thus evidently improving its mechanical and durability of concrete when compared to the reference specimen without MK. Although the properties of concrete blended with CG and CWP as part of coarse aggregate are inferior to pure natural gravel contained concrete, its strengths and resistance to chloride ion permeability can achieve requirements of engineering structures.

This study evaluated the strength and durability characteristics of pond ash (PA) treated with geopolymer (3%, 6%, 9%, 12%, and 15%, by dry weight of PA) and compared them with Portland cement and hydrated lime stabilizations at same additive contents. Unconfined compressive strength of specimens was evaluated at curing durations of 1, 3, 7, 28, and 90 days. The durability of 28-day cured stabilised specimens against wet-dry cycles, freeze-thaw cycles, water slaking cycles, water immersion, capillary action, and dispersion was assessed. Geopolymer-stabilized PA achieved higher strength and durability than cement and lime-stabilised PA. It is due to the formation of a dense microstructure with significant reaction products. PA stabilised with 3% geopolymer and 15% cement satisfies the strength properties of the cementitious subbase in flexible pavements. Whereas, 6% geopolymer content fulfils the requirements of the cementitious base in flexible pavements and the cementitious subbase in rigid pavements as per IRC: 37-2018 and IRC: 59-2015, respectively.

Marine soft soils, characterized by high water content and low strength, present significant challenges to foundation stability. These soils often lead to settlement and uneven deformation, posing risks to infrastructure safety. This study tackles these challenges and promotes industrial waste utilization by developing a novel curing material for marine soft soils. The material consists of ground granulated blast furnace slag (GGBS), phosphogypsum (PG), and calcium carbide slag (CCS), and is compared to ordinary Portland cement (OPC). A D-optimal design was employed to establish regression equations for unconfined compressive strength (UCS) at 7 and 28 days. The interactions between factors were analyzed to optimize the mix ratio. The effects of different curing ages on the unconfined compressive strength, modulus of elasticity, moisture content, and pH of GPCOR solidified soft soil and cement solidified soil were investigated. The microstructure of the solidified soils was analyzed using SEM, XRD, FTIR, and BET techniques. The results indicated that the optimal GPC ratio was GGBS: PG: CCS = 64.81: 20.00: 15.19. After 28 days, GPCOR solidified soil exhibited superior UCS (4.48 MPa), 1.47 times greater than that of OPC solidified soil, and a deformation modulus 2.04 times higher. Furthermore, GPCOR exhibited a denser microstructure with smaller average pore sizes, improved durability, and better water retention than OPC. These findings underscore the potential of GPC as a sustainable alternative to conventional cement for reinforcing marine soft soils, promoting both soil stabilization and industrial waste resource utilization.

AimsEnvironmental stresses can influence root mechanical strength, the impact of submersion of the water level fluctuation zone on the root mechanical strength of Cynodon dactylon was evaluated in this study.MethodsVariations in the physicochemical properties (root weight density and root activity), mechanical strengths (tensile and pullout strength) and failure types of C. dactylon roots were investigated using a submersion experiment with 8 durations (0, 15, 30, 60, 90, 120, 150, 180 d), with a treatment without submersion serving as the control (CK). Additionally, corresponding variation in the microstructure of the roots was observed.ResultsThe root weight density, root activity, root tensile strength and pullout strength of C. dactylon rapidly decreased, followed by a gradual decrease with increasing duration, and the reductions during the first 15 d of submersion accounted for 65.15%, 75.86%, 61.14% and 68.26% of the maximum reduction during the submersion process, respectively. Negative power function relationships were found between root mechanical strength and root diameter. Submersion increased the proportion of fracture failures during the pullout process. Moreover, the influence of submersion on root mechanical strength and failure type was regulated by a reduction in root activity.ConclusionsSubmersion deteriorates the mechanical properties of C. dactylon roots and alters their failure type.

Dispersive clay is widely distributed in the Songnen Plain of northeast China, causing serious embankment damage to hydraulic engineering, and the research on the relevant failure mechanism is still incomplete. In this study, based on the real stress path of dispersive clay failure, a mechanical experimental method under plane strain conditions was adopted to investigate the strength properties of dispersive clay. The results showed that under plane strain conditions, the stress-strain curve of dispersive clay exhibited the strain hardening type, distincted from the conventional strain softening type under triaxial vertical conditions, and the strength difference was approximately twice at a consolidation stress of 50 kPa. The stress-strain relationship of the principal stress also showed the strain hardening type, and the relationship between the stress-strain was approximately linear. Under low consolidation stress, the coefficient of the intermediate principal stress reached 0.44, indicated a significant influence of the intermediate principal stress on the strength of the clay. Under low consolidation stress, the failure mode of dispersive clay was characterized by swelling with no obvious spatial shear band, while under high consolidation stress, the failure mode exhibited a shear band located diagonally. Additionally, the strength properties of dispersive clay were weakened by the leaching of chemical ions in the clay, showed different compaction and strength under different consolidation stresses.