The large-scale development of urban underground spaces has resulted in hundreds of millions of cubic meters of accumulated shield soil dreg waste, occupying huge amounts of land resources and potentially causing groundwater pollution and soil salinization. In this study, shield soil dreg waste is recycled and activated to substitute cement in ultra-high performance concrete, aiming to promote solid waste management and sustainable construction. The slump, mechanical performance, and autogenous shrinkage of the concrete are investigated through macro-scale tests, and the underlying mechanism is revealed via micro-scale experiments. The incorporation of calcined shield soil dreg reduces flowability and leads to a 10.2 % deterioration in compressive strength of the ultra-high performance concrete while mitigating autogenous shrinkage. The primary reason is due to the low CaO content of shield soil dreg, which limits the formation of calcium silicate hydrate, and its high SiO2/Al2O3 content slows hydration kinetics. The environmental and economic benefits of the concrete are determined via life cycle analysis. Recycling shield soil dreg waste into concrete results in about 35 % reduction in carbon emission and 22 % reduction in energy consumption. According to multi-criteria assessment, the overall performance of the concrete considering economic cost, environmental benefit, as well as physical and mechanical properties increases compared to the pristine concrete, achieving well-balanced economic feasibility, environmental sustainability, and engineering performance. The findings of this study provide an effective approach for recycling shield soil dreg and preparing low-carbon concrete, thus promoting solid waste management and sustainable construction.

Phenolic foam (PF) produces much PF waste during processing because of its friability and tendency to pulverize. Currently, commonly used disposal methods like incineration and landfill cause air and soil pollution. Moreover, protective polyurethane foam (PUF) requires both excellent acoustic insulation and mechanical strength in scenarios, such as factories and roads, to enhance environmental comfort and safety. In this study, PF waste was recycled via a mechanical method, and compounding the recycled PF powder as a functional filler with PUF significantly improved its mechanical and acoustic properties. The sample (PUFB-2.5) with 2.5 g PF powder added achieved a compressive strength of 372.19 kPa, 99.03% higher than the standard foam sample (PUFB-0). Additionally, the sample (PUFB-10) with 10.0 g PF powder added achieved an optimal average sound absorption coefficient (alpha) of 0.59, 63.89% higher than PUFB-0. In the 400-2400 Hz frequency range, sample PUFB-2.5 displayed superior sound absorption properties, with alpha reaching 0.78. This study not only achieves the recyclable and circular utilization of PF waste but also enhances the mechanical and acoustic properties of PUF and offers new paths for the convergence of material science and environmental engineering industries.

Eutrophication and ecosystem damage result from phosphate pollution. Competing ions make extracting trace phosphate under 2.0 mg/L from treated wastewater difficult. However, if the phosphate could be sustainably recovered or reused in agriculture, considerable savings in fertilizer could be made. On the other hand, agricultural waste, which is a menace, contains a significant amount of cellulose that finds interesting applications as a biodegradable material. This study synthesized a cellulose-based adsorbent with iron hydroxide nanoparticles from nano-fibrillated cellulose (CNF) from agricultural waste and carboxymethyl cellulose (CMC). It selectively removed phosphate from secondary treated wastewater. Fe(OH)3@CNF/CMC (FCC) removed 3 mg/g phosphate. The hydrogel-like material quickly absorbed 40 g/g of water and slowly released it for a week when dry. Soil burial test indicates microorganisms biodegraded 80 % of the hydrogel in 3 months. After these findings, we delivered plant nutrients using the phosphate-rich exhausted FCC adsorbent. Results showed that phosphate-rich FCC improved seed germination and plant growth. Phosphate-loaded FCC adsorbent promoted better plant growth than single super-phosphate and control samples. This study creates a circular economy-based slowrelease fertilizer from agricultural waste and secondary-treated wastewater. This approach uses the 3 R rule-recycle, recover, and reuse-to benefit society ecologically and economically.

In the cotton fields in Xinjiang, residual film is present in the soil for a long period of time, leading to a decrease in the tensile strength of the residual film and increasing the difficulty of recycling. Existing technologies for residual film recovery focus on mechanical properties and ignore the dragging and tearing of residual film by cotton stubble. The effect of cotton straw-root stubble on residual film recovery can only be better determined by appropriate machine operating parameters, which are essential to improving residual film recovery. Through analyses of the pickup device, key parameters were identified, and a model was built by combining the FEM and SPH algorithms to simulate the interaction of nail teeth, residual film, soil and root stubble. The simulation revealed the force change law of residual film in root stubble-containing soil and the influence of root stubble. By simulating the changes in the characteristics of the residual film during the process, the optimum operating parameters for the nail teeth were determined: a forward speed of 1849.57 mm/s, a rotational speed of 5.5 r/s and a soil penetration angle of 30 degrees. Under these optimized conditions, the maximum shear strain, pickup height (maximum deformation) and average peak stress of the residual film were 1293, 363.81 mm and 3.42 MPa, respectively. Subsequently, field trials were conducted to verify the change in the impact of the nail teeth at the optimized speed on the recovery of residual film in plots containing root stubble. The results demonstrated that when the root stubble height was 5-8 cm, the residual film averaged a recovery rate of 89.59%, with a dragging rate of only 4.10% at crossings. In contrast, 8-14 cm stubble plots showed an 82.86% average recovery and an 11.91% dragging rate. In plots with a root stubble height of 5-8 cm, compared with plots with a root stubble height of 8-14 cm, the recovery rate increased by 6.73%, and the dragging rate of residual film on root stubble decreased by 7.81%. The percentage of entangled residual film out of the total unrecovered film was 30.10% lower in the 5-8 cm stubble plots than in the 8-14 cm stubble plots. It was confirmed that the effect of cotton root stubble on residual film recovery could be reduced under appropriate machine operating parameters. This provides strong support and a theoretical and practical basis for future research on the correlation between root stubble and residual film and how to improve the residual film recovery rate.

Underground structures are subject to deterioration conditions in which water leakage occurs through cracks due to the long-term influence of soil and groundwater. Therefore, composite waterproofing sheets can play an important role in securing the leakage stability of structures by combining them with concrete structures. In this study, a total of eight composite waterproofing sheets were used according to the thickness of the compound and the properties of the material attached to the concrete, and the deformation characteristics at the bonding surface were identified through repeated tensile tests. Types A, B, and C, with a compound thickness of 1.35 to 1.85 mm and a single layer, had strong bonding performance, with a deformation rate of 0.5 to 2 x 10-4 and a DE/RE ratio of 0.3 to 1.3; tensile deformation progressed while maintaining integrity with the concrete at the bonding surface. Types D and E were viscoelastic and non-hardening compounds with a compound thickness of 1.35 to 3.5 mm, where the strain rate due to tensile deformation was the lowest, at 0.1 x 10-4 or less, and the DE/RE ratio was -5 to 3; therefore, when internal stress occurs, the high-viscosity compound absorbs it, and the material is judged to have low deformation characteristics. Types F, G, and H, which were 2 to 2.9 mm thick and had two layers using a core material, were found to have characteristics corresponding to tensile deformation, as the strain rate increased continuously from 0.2 to 0.5 x 10-4, and the DE/RE ratio increased up to 8 mm of tensile deformation.

The use of abrasive waterjets (AWJs) for rock drilling offers advantages in urbanized areas, locations that are vulnerable to damage, and piling operations. However, the overall operational cost of AWJ systems remains high compared to that of conventional drilling methods, which constrains the long-term industrial application of AWJs. For instance, the abrasive costs account for over 60% of the total process cost, but the recycling of abrasives remaining after drilling could significantly reduce machining costs. In this study, the post-impact characteristics of abrasives were explored, aiming to enhance their recyclability. The physical properties and particle distribution of used abrasives vary depending on the jet energy, ultimately affecting their recyclability and recycling rate. The particle properties of used abrasives (particle size distribution, particle shape, and mean particle size) were compared under different waterjet energy variables (standoff distance (SOD) and water pressure) and test conditions (dry and underwater). Furthermore, the collision stages of the abrasive particles within a waterjet system were classified and analyzed. The results revealed that abrasive fragmentation predominantly occurred due to internal collisions within the mixing chamber. In addition, an attempt was made to optimize the waterjet parameters for an economical and efficient operation. The findings of this study could contribute to enhancing the cost-effectiveness of AWJ systems for rock drilling applications. (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/).

Reuse of greywater for irrigation has surged due to increasing urban freshwater scarcity. Greywater sources differ in ease and cost of reuse, with limited studies on the effects of irrigation with different sources on soil properties and subsequent rainwater remediation. Thus, this study compared the effect of four major household greywater sources (shower (SH), dishwasher (DW) and liquid and powdered laundry detergent (LLD and PLD)) on soil properties and rainwater remediation potential of two contrasting (albic Planosol (bleached) and Lixisol (rhodic)) topsoils under Mediterranean climate conditions. Summer irrigation with the greywater and tap water sources was simulated (370 mm) followed by winter rainfall simulation (370 mm). Soil chemical, physical and microbial properties were determined after each simulation. Irrigation with SH and LLD greywaters was least harmful to soil chemistry; however, LLD decreased soil infiltration rate by 48-53%, and SH resulted in hydrophobic crusting. Irrigation with PLD and DW greywater was most damaging, resulting in alkalisation, sodification and salinisation accompanied by soil structural degradation, decreasing infiltration by 85-100%. All treatments reduced soil bacterial diversity and species richness. Rain simulation was only able to reduce sodicity and salinity associated with PLD and DW application on the rhodic soil, as the clay fraction was more stable, permitting some infiltration. Therefore, PLD and DW greywaters should not be used directly for irrigation, especially on bleached soils, as this can halt rainwater percolation. Furthermore, use of less chemically harmful SH or LLD liquid greywaters could result in undesirable soil physical problems in the long term.

Protein-based foams are potential sustainable alternatives to petroleum-based polymer foams in e.g. single-use products. In this work, the biodegradation, bioassimilation, and recycling properties of glycerol-plasticized wheat gluten foams (using a foaming agent and gallic acid, citric acid, or genipin) were determined. The degradation was investigated at different pH levels in soil and high humidity. The fastest degradation occurred in an aqueous alkaline condition with complete degradation within 5 weeks. The foams exhibited excellent bioassimilation, comparable to or better than industrial fertilizers, particularly in promoting coriander plant growth. The additives provided specific effects: gallic acid offered antifungal properties, citric acid provided the fastest degradation at high pH, and genipin contributed with cross-linking. All three additives also contributed to antioxidant properties. Dense beta-sheet protein structures degraded more slowly than disordered/alpha-helix structures. WG foams showed only a small global warming potential and lower fossil carbon emissions than synthetic foams on a mass basis, as illustrated with a nitrile-butadiene rubber (NBR) foam. Unlike NBR, the protein foams could be recycled into films, offering an alternative to immediate composting.

Jarosite is an inorganic byproduct waste produced during the purification and refining of zinc in the industry. Recycling such waste as a filler in biocomposites could be a sustainable solution to manage it. To create jute-jarosite-soy biocomposites, varying weight percentages of jarosite are combined with soy resin and applied to woven jute cloth. The impact of jarosite on the mechanical characteristics, hardness, fire retardant, thermal stability, hydrophobicity, and degrading nature of jute-soy composites was investigated, and it was discovered that its presence by a part of 3 weight percentage enhanced tensile strength by 37.2% and flexural strength by 34.7%, respectively. The hardness and thermal stability of jute-jarosite-soy composites are enhanced by 17.5% and 35.8%, respectively, over jute-soy composites. After 60 days, soil burial analyses of these composites revealed more than 70% weight loss. Due to its moderate strength and entirely biodegradable nature, manufactured jute-jarosite-soy composite can be used to replace non-degradable thermoplastic usage in several sectors.

Biopolymer-bound soil composites (BSC) area novel class of cement-free building materials using biopolymer binders, many of which are sourced from the waste streams of major industries. This study investigates the recyclability of one particular BSC that uses kraft lignin as the biopolymer. Re-manufacturing of BSC was accomplished by mechanical disruption of the virgin material, followed by re-introduction of solvent, remixing, and remolding. The compressive strength of recycled lignin-based BSC was higher than that of BSC made with virgin ingredients. To understand the microstructure of lignin-based BSC, a series of X-ray micro-CT images of the test articles were obtained. Images produced by the micro-CT method reveal differences in the microstructure of the re-manufactured specimens indicating an enhancement of the association between lignin and aggregate particles. This study demonstrates the feasibility of recycling BSC and provides insight into the importance of biopolymer-aggregate association in determining the mechanical properties of BSC.