The ocean's extreme environments demand robust materials for next-generation exploration tools. Here, we report a multifunctional poly(vinyl alcohol) hydrogel (PVA-H) fabricated via universal solvent-induced crystallization for bioinspired robotic fish skins. Alkaline solvent induction triggers intrachain crystallization within concentrated PVA solutions, yielding hydrogels with exceptional mechanical strength (compressive strength up to 2.6 MPa, tensile strain >450%), environmental tolerance (resilience to 1 M acetic acid/NaOH, seawater, 3 M NaCl), and optical transparency (>80%). The material demonstrates efficient recyclability (>90% recovery over 10 cycles) and biocompatibility (hemolysis rate <1.5%). Ionic compounding enables stable underwater conductivity and antifreezing performance at -20 °C. Hydrophilicity-driven interfacial water layers inhibit >70% protein adsorption, which confers antifouling properties. Integration of ice templating and solvent crystallization facilitated scalable fabrication of biomimetic fish skins, validated through sustained underwater operation. This work establishes a versatile platform for durable, eco-adaptive marine robotics operating in chemically, thermally, and biologically hostile environments.

The leather industry generates substantial solid waste, with shaving and buffing dust comprising approximately 20% of total tannery residues. Improper disposal of this protein-rich chromium-containing waste leads to significant environmental pollution. The feasibility of incorporating leather shaving and buffing dust, combined with rice husk ash (RHA) and river sand, into non-fired bricks, aiming to convert waste into sustainable construction materials, was investigated. Bricks were fabricated by partially replacing clay (0-20 wt%) with a mixture of leather dust and RHA in varying proportions, with and without cement, and were cured for 7, 14, and 28days. Comprehensive characterization, including FT-IR, XRD, WD-XRF, TGA/DTG, XPS, and leaching tests, was conducted to evaluate physicochemical, mechanical, and environmental performance. The presence of chromium predominantly in the stable trivalent state (Cr3+) and its effective encapsulation within the brick matrix was confirmed by XPS analysis. The optimal composition, containing 10% leather dust and RHA with Gazipur Clay and 15% cement, achieved a compressive strength of 20.03MPa at 28days, meeting ASTM and BDS standards. Chromium leaching remained well below permissible limits, indicating effective immobilization. A time-dependent increase in chromium leaching was observed (0.1562ppm at 7days to 0.40195ppm at 28days), reflecting a diffusion-controlled release, yet remained well below permissible limits, demonstrating effective immobilization. Circular economic principles are supported by this approach by transforming hazardous waste into value-added construction materials. The findings suggest significant potential for industrial-scale application of leather waste-based bricks, contributing to sustainable, cost-effective, and eco-friendly building material production.

Recycled concrete aggregate (RCA) exhibits challenges like weak bonding, high porosity, and inferior strength compared to natural aggregates. This study evaluates the effect of epoxy resin polymer treatment on RCA on enhancing compressive and split tensile strengths in concrete, replacing natural aggregates with untreated RCA (UTRAC) and treated RCA (ERTAC) at 25%, 50%, 75%, and 100% levels. The tests were conducted at 3, 7, and 28 days. UTRAC showed reductions of up to 26.32% in compressive strength and 35.38% in tensile strength at 100% replacement; ERTAC outperformed control concrete (CC) with gains of up to 26.32% in compressive strength (at 25%) and 122.73% in tensile strength (at 100%), identifying 25% as the optimum replacement ratio. SEM and XRD analyses confirmed improved particle packing, reduced porosity, and stronger interfacial transition zones (ITZ) in ERTAC.

This study investigates the effects of expanded polystyrene (EPS) beads and printing direction on the fresh and hardened properties of 3D printable lightweight concrete (epscrete) mixtures. In the experimental studies, control samples containing only sand, mixtures containing only EPS and sand-EPS mixtures with different ratios were prepared and various experiments such as workability, shape retention, unit weight, ultrasound transmission velocity, compressive strength, flexural strength and splitting tensile strength tests were performed on these specimens. In addition, the effects of printing and loading directions on the mechanical strength of epscrete mixtures were investigated. The results show that EPS beads improve the rheological properties of fresh concrete and increase workability, but cause a significant decrease in shape retention ability, especially at high EPS ratios. In terms of hardened concrete properties, it was determined that mechanical strength decreases as the EPS ratio increases, but sufficient load-bearing capacity can be provided with compressive strengths exceeding 30 MPa in all directions in mixtures containing 50% EPS. In addition, higher compressive strength is observed under loading perpendicular to the printing direction, while the strength is lower on the interlayer bonding surfaces. Microstructure analyses revealed that ettringite formations are intense in the transition zone between EPS and cement matrix and this increased porosity within the structure adversely affects the overall strength. These results show that lightweight concretes with EPS content, known for their advantages such as lightness and thermal insulation, have potential for 3D printable low-rise and lightweight building applications.

ABSTRACT Recycled aggregate concrete (RAC) offers sustainability advantages but often shows reduced strength and durability compared with normal aggregate concrete (NAC). This review evaluates the role of basalt fibers (BF) in improving the performance of both NAC and RAC, drawing on over 150 experimental studies. Results show that properly selected BF dosages can enhance compressive, splitting tensile and flexural strengths by up to about 25%, 35%, and 60%, respectively. Most effective mixtures use 0.1–0.5% BF by volume with fiber lengths of 6–18 mm. In RAC, BF performs best at moderate recycled aggregate replacement levels of 40–50%, where it can significantly recover strength losses and, in several cases, achieve compressive strengths above 55 MPa. At these levels, BF also refines pore structure and improves resistance to freeze – thaw damage and chloride penetration. However, excessive dosages (≥0.6%) frequently reduce workability and promote fiber clumping and higher porosity. Overall, the findings show that optimized BF content and geometry, together with appropriate RAC mix design and aggregate treatment, can yield more durable and sustainable concrete, while underscoring the need for further research on hybrid fiber systems and performance prediction models for BFRC.

Additive manufacturing (AM) of heat-resistant high-strength aluminum (Al) alloys for load-bearing components faces a fundamental dichotomy: traditional high-strength compositions suffer from hot cracking, while printable alloys lack sufficient high-temperature strength. This inherent conflict severely restricts the design space for novel alloys in demanding applications like aerospace. Addressing this challenge, a data-driven design strategy leveraging quantum machine learning (QML) and high-throughput computing identifies an ultrastrong Al85Cu5Li4Mg3Zn3 lightweight Al-based entropy alloy (LAEA) tailored for AM. The AM process transforms potentially brittle microsized intermetallic compounds into deformable hierarchical nanostructures of cellular eutectics, quasicrystals, and dense nanosized planar defects (stacking faults, nanotwin boundaries, and 9R phases). This intricate microstructure endows the as-printed alloy with exceptional properties: an ultrastrong compressive strength exceeding 1000MPa coupled with considerable plasticity (∼20%), outstanding high-temperature strength (>800MPa at 200°C), and a specific strength (350×103 N m/kg) rivaling titanium alloys. Furthermore, a controllable quasicrystal-to-crystal phase transformation activated by thermal exposure offers an additional mechanism for precisely tuning mechanical properties post-fabrication. This work presents a novel design paradigm for AM-compatible high-performance lightweight Al-based entropy alloys (LAEAs), effectively bridging advanced computational material design and advanced manufacturing.

The construction sector faces the dual challenge of reducing energy consumption and mitigating the environmental burden of construction and demolition waste (CDW). Geopolymers offer a low-carbon alternative to Portland cement, yet their performance depends strongly on precursor composition. This study presents an extensive investigation of precursor chemistry, mechanical performance and phase composition, focusing on the partial substitution of ground granulated blast furnace slag (GGBFS) with mechanically activated CDW powder (15% and 30% by weight) alongside fly ash (FA). The oxide composition, amorphous content and particle size distribution were analyzed, using XRF, XRD and laser diffraction to evaluate the reactivity. Mortar samples were subsequently synthesized and tested for compressive and flexural strength, ultrasonic pulse velocity, density and porosity. The results demonstrate that while mechanically activated CDW incorporation decreases early strength compared with GGBFS-rich systems, compressive strengths above 45 MPa were attained at 28 days, with continuous improvement to &gt;69 MPa for aged composites. The relationship between precursor chemistry, precursor sizes and mechanical performance highlights the feasibility of CDW valorization in geopolymer binders, contributing to energy efficiency, circular economy strategies and sustainable construction materials.

To address winter construction challenges such as slow early-stage strength development, inhibited hydration processes, and pore structure defects in concrete under low-temperature conditions, this study employs nano-TiO2 as a modifying agent. It is incorporated into concrete through cement replacement methods; the study systematically investigates the influence of different admixture dosages (1%, 2%, 3%, by cement mass) on the mechanical properties, hydration process, and micro-pore structure of concrete. The test employed an electro-hydraulic servo universal testing machine to measure compressive and splitting tensile strengths. Differential thermal analysis (DTA) characterized the formation of hydration products (Ca(OH)2). Micro-CT technology and pore network modeling were utilized to quantify micro-pore parameters. Results indicate that (1) nano-TiO2 regulates the setting time of pure paste, with increased dosage shortening both initial and final setting times. At a 3% dosage, initial setting time plummeted from 5.5 min in the control group to 3.3 min; (2) nano-TiO2 significantly enhances early-age (1–3 days) strength of low-temperature concrete, with optimal effect at 1% dosage. Compressive strength and splitting tensile strength at 1 day increased significantly by 20% and 26%, respectively, compared to the control group. Strength differences among groups gradually narrowed at 28 days; (3) DTA indicates that nano-TiO2 accelerates early cement hydration; (4) micro-CT results show that the 1% dosage group exhibits significantly reduced porosity at day 1 compared to the control group, with notable decreases in Grade 0 and Grade 1 interconnected porosity resulting in the most optimal pore structure density. In summary, the optimal dosage of nano-TiO2 in low-temperature environments is 1% by mass of cement. Through the synergistic “nucleation-filling effect,” it promotes early-stage hydration and optimizes pore structure, providing technical support for winter concrete construction.

In response to growing interest in green additives derived from natural raw materials or post-production waste of natural origin, epoxy compositions containing the additive in the form of waste wood flour and microcellulose were prepared. The research involved the chemical modification of the additive through a two-stage silanization process using 3-aminopropyltriethoxysilane. Followed by filler’s characterization using Fourier Transformed Infrared Spectroscopy (FT-IR) to analyze the modification in chemical structure, Wide Angle X-Ray Diffraction (WAXD) to detect differences in crystal structure, and Scanning Electron Microscopy (SEM) to observe morphological changes. Next, waste oak flour (WF) and microcrystalline cellulose (MCC) were used in unmodified and silanized form (sil-WF and sil-MCC, respectively) to prepare epoxy composites, followed by testing their influence on the mechanical (hardness, tensile strength, flexural strength, compressive strength, and impact strength), thermal, and morphological characteristics of epoxy composites based on Epidian 6. Comparing the effect of modification on the properties of the analyzed additives, it was found that silanization had a larger impact on increasing the interaction of the waste wood flour with the epoxy matrix than silanization of MCC due to a lesser tendency of the sil-WF than the sil-MCC to agglomerate. An enhanced interaction of sil-WF with the polymer resulted in improved mechanical properties. Composite EP/sil-WF (cured epoxy composite based on low-molecular-weight epoxy resin Epidian 6 filled with 5 wt.% of silanized wood flour) was characterized by improved flexural (61.97 MPa) and compressive properties (69.1 MPa) compared to both EP/WF (cured epoxy composite based on low-molecular-weight epoxy resin Epidian 6 filled with 5 wt.% of unmodified wood flour) (42.39 MPa and 61.0 MPa) and the unfilled reference composition (54.55 MPa and 67.4 MPa, respectively). Moreover, compositions containing a cellulosic additive were characterized by better impact properties than the reference composition.

In coastal saline soil regions, foundation instability frequently arises due to salt heave, dissolution-induced weakening and corrosion-driven degradation. To enhance the engineering performance of fine-grained saline soil, this study evaluates the effectiveness of Enzyme-Induced Carbonate Precipitation (EICP) treatment under varying salinity levels and curing solution concentrations. Mechanical properties, hydraulic behavior and water stability were examined through unconfined compressive strength (UCS), disintegration and permeability tests, complemented by microstructural analyses using XRD and SEM. The results indicate that EICP notably improves mechanical strength, water stability and reduced permeability. The UCS of treated specimens increased by 37–152% relative to untreated soil, and disintegration time was prolonged by 214–563%. The permeability coefficient was reduced by 45.8–95.7%, demonstrating effective suppression of seepage channels. The optimal stabilization performance was achieved at 0.02% salinity and curing concentrations of 1.0–1.3×. Excessive salinity distorted vaterite crystal morphology and weakened cementation. XRD and SEM analyses revealed that vaterite dominated the calcium carbonate polymorphs, while ionic complexity influenced crystal structure, ACC conversion and pore-filling performance. These findings confirm the feasibility of applying EICP for improving fine-grained coastal saline soils and provide practical engineering guidance for coastal subgrades, reclamation foundations and port infrastructures.

Gambier is one of the largest sources of condensed tannins in Indonesia which has the potential as a raw material for rigid foam. Environment friendly rigid foam can be made from a mixture of gambier tannin, albumin, pTSA and hexamine. The purpose of this study was to investigate how albumin preparation and gambier tannin extraction methods affect the quality of rigid foam. Albumin preparation was carried out by a fermentation process using Rhizopus sp. yeast and then drying using the pan drying and foam drying methods. Extraction was carried out by heating using a magnetic stirrer and microwave-assisted methods. Based on the results of the study, the best rigid foam is the rigid foam with a combination of pan drying and microwave assisted. This rigid foam has a high density, high compressive strength, low swelling degree, resulting in a denser and harder rigid foam and based on SEM test showed closed and open pores in the rigid foam with a pore size of around 60.47 µm. Keywords: Secondary metabolites, hydrolyzed tannins, Maillard reaction, tannins extract.

Compressive strength prediction of carbonated recycled aggregate concrete using regression based machine learning models.

Mortise-and-tenon precast concrete (MTPC) beam–column joints utilize a mortise–tenon structure with longitudinal prestressing to secure their connections. This approach offers advantages such as dry construction, easy assembly, a short construction period, and the possibility of disassembly. To meet the “strong joint” requirement, this study enhances the core areas of the joints through ultra-high–performance concrete (UHPC) reinforcement and rebar enhancement. First, the structure and assembly method for MTPC joints are introduced. Subsequently, five distinct specimens are fabricated for testing: two UHPC-reinforced models, one rebar-enhanced model, one standard MTPC joint model, and one cast-in-place joint model. All specimens are then subjected to monotonic axial compression tests. The results show that the optimized MTPC joints exhibit significantly improved axial compressive strength, reaching 90% to 100% of the capacity of the cast-in-place joint. With regard to the optimization methods, whereas increasing rebar ratios enhances axial strength, it does not fully achieve the “strong joint” criterion. By contrast, UHPC reinforcement significantly boosts axial compressive capacity, achieving the desired “strong joint” standard. After axial load is used to compact the assembly gaps in MTPC joints, the overall integrity is made strong, axial stiffness remains stable, and the load transfer path becomes clear. With UHPC reinforcement, force transmission through the MTPC joint components becomes more reliable, with the tenon bearing more axial load; however, the tenon should not be used as the main vertical force transmission section. Finally, it is found that the axial compressive load capacity calculation method recommended by the Chinese code can accurately and safely predict the axial compressive load capacities of MTPC joints.

To evaluate the fire safety performance of the joint region in prefabricated buildings, specifically when the grout in the slurry layer is under an unconstrained state. Total 54 pull-out specimens were designed to investigate the effects of elevated temperatures (20 °C, 200 °C, 300 °C, 400 °C, 500 °C, and 600 °C) and steel bar positions (center, mid-side, and corner) on the bond behavior between the grout and steel rebars. The failure modes, bond strength, ultimate displacement, and load–slip curves of the specimens were recorded. The peak load of the specimens with the temperature increasing first rose and then declined, exhibiting a trend consistent with the variation in compressive strength of the grout with temperature. At 600 °C, the ultimate loads of the center, mid-side, and corner specimens decreased by 53.46%, 52.53%, and 51.28%, respectively, compared with those at ambient temperature. At ambient temperature, the bond strength of the mid-side specimen was 11.24% lower than that of the central specimen, but 19.98% higher than that of the corner specimen. At 500 °C, the bond strength of the mid-side and corner specimens decreased by 15.76% and 39.26%, respectively, compared with that of the center specimen. The failure mode changed from steel-rebar fracture to pull-out failure due to the high temperature exposure and the steel rebar position. Finally, based on the post-heating strength test results of grout specimens, a bond strength calculation formula and a bond–slip constitutive model, considering both steel rebar position and temperature, were developed, achieving a correlation coefficient (R2) close to 1.0.

A series of sulfobetaine-modified poly(butylene succinate) copolymers (P(BSn-co-cBSm)-S-SBp) were synthesized by varying the feed ratio of unsaturated cis-butene-1,4-diol (cBS). Six bulk disc films were fabricated, exhibiting a minimum compressive strength exceeding 30 MPa when the sulfobetaine content was between 1% and 2.5%. Notably, the zwitterionic side chains enhanced hydrophilicity and surface wettability, improving lubricity (low friction). Albumin adsorption tests revealed a 43% suppression compared to the unmodified film. The films remained stable, with cumulative weight loss ranging from less than 1% to 10% over a 45 day period under ambient hydrolytic conditions. These results highlight the potential of sulfobetaine-functionalized PBS for future utility in load-bearing or supportive materials.

Abstract Incorporating steel slag, a residue derived from the metallurgical industry, into cementitious systems offers a sustainable route for resource recovery and carbon footprint reduction. Milling has been reported to address the low cementitious reactivity of steel slag, which remains a significant barrier to its widespread adoption. However, the influence of storage duration after milling on steel slag performance has not been systematically evaluated. To investigate the effects of post-milling duration as an independent factor, two types of steel slag, derived from a basic oxygen furnace and an electric arc furnace processes, were milled using planetary ball milling and stored under controlled environmental conditions for 1 h, 1 day, 4 days, 7 days, 3 months, and 1 year. The results showed that prolonged storage caused significant particle agglomeration, detected by particle size analysis, and a slight reduction in reactivity after 1 year, as determined by the Rapid, Reliable Relevant ( R 3 ) reactivity test for supplementary cementitious materials. Replacing 30% of cement with steel slags stored for different times (1 h vs. 1 year) changed the properties of the blends. Compared with freshly milled slag, slag stored for 1 year caused a slight delay in cement hydration, as evidenced by calorimetry results. Consequently, blends containing 1-year-stored slag exhibited prolonged setting times and reduced apparent viscosity compared with the 1-h slag–cement blends. The compressive strength of blended cements was also negatively affected by long-term storage, and the amount of hydration products, such as portlandite, was slightly reduced in 28-day composites containing 1-year-stored slag. Graphical Abstract

This study proposes a novel, unified framework integrating scientometric analysis, machine learning (ML), explainable artificial intelligence (XAI), and cradle-to-gate life cycle assessment (LCA) to evaluate and predict the performance of slag-fly ash-based geopolymer concrete (SFGPC). A scientometric review of 441 publications (2009–2025) guided the systematic assembly of a dataset comprising 363 SFGPC mixes. Five ML models were trained to predict compressive strength (fc), with Gradient Boosting (GB) achieving the highest accuracy, yielding R2 = 0.954, RMSE = 3.15 MPa, MAE = 1.81 MPa during training, and R2 = 0.95, RMSE = 3.128 MPa, MAE = 2.41 MPa during testing. Multi-layered XAI analysis identified age, slag content, and alkaline-to-binder ratio as the most influential parameters and revealed governing nonlinear interactions. Sustainability assessment showed that the fly ash-dominant mix exhibited the lowest global warming potential (156 kg CO2-eq/m3), the most favourable sustainability index, and the smallest residual emissions after a 25% carbon offset. A user-oriented graphical user interface (GUI) was developed for real-time strength prediction. The novelty of this work lies in introducing an explainable, data-driven, and sustainability-integrated decision-support system for designing transparent and low-carbon geopolymer concretes.

This study develops soft-computing models to predict the compressive strength of Fly Ash Composite Foam Concrete (FFC), a lightweight, sustainable cementitious material. A database of 302 experimental records was compiled from previous studies, including wet density, cement content, fly ash content, sand content, water–binder ratio, foam content, and curing age. Five predictive models were evaluated, with the Artificial Neural Network (ANN) achieving the best performance, yielding an accuracy of 98% and the lowest prediction error. Sensitivity analysis identified wet density, cement content, and foam content as the most influential variables. The results demonstrate that soft computing approaches can significantly reduce experimental effort, lower costs, and support the sustainable design of FFC mix ratios for diverse applications.

Economic investment and mechanical characteristics represent primary limitations to the widespread adoption of cemented tailings backfill. This study introduces an approach of using quarry waste to generate rock powder, which is subsequently mixed with tailings to produce cemented tailings-rock powder backfill (CTRPB). This method achieves cost efficiency while facilitating synergistic waste management. Through uniaxial compression testing, the influences of rock powder type and content on the mechanical behavior, failure modes, and energy transformation of CTRPB were examined. A piecewise damage constitutive model was developed to explore damage progression mechanisms. Findings demonstrate that the incorporation of rock powder markedly improves the deformation resistance of CTRPB. Both uniaxial compressive strength (UCS) and elastic modulus exhibit an initial increase followed by a decline as content rises, with optimal levels and enhancement effects differing across various rock powders. The failure process of CTRPB encompassed four distinct phases, where rock powder amplified post-peak energy release and fragmentation behaviors. Energy assessment indicated that rock powder significantly boosted energy storage and dissipation capacities, elevating total energy density, elastic energy density, and dissipated energy density by 252.17%, 213.87%, and 478.99%, respectively. The formulated piecewise damage constitutive model correlated well with experimental data in the pre-peak regime. Damage evolution may be categorized into four stages, and damage values can act as indicators for assessing failure conditions in the resource utilization of mining waste and rock powder-tailings backfill technology. This research offers a theoretical foundation for the resource-oriented use of mine waste and rock powder-tailings backfill technology.

Around 20% of the fruits and vegetables produced globally are lost between harvest and retail owing to infrastructure and logistics challenges. There are no technologies available to utilize this waste comprehensively, which amounts to billions in economic losses annually. While methods are available for extraction of bio-active compounds, the technologies to harness fibers and sugars which are the major components of the waste are not reported. This work reports a new technique for valorization of waste onion, as it consists of carbohydrates and fibers and represents the typical composition of food and vegetable waste. The controlled oxidation of onion waste under ambient conditions led to decomposition of 90% of the sugars which resulted in crosslinking of the fibers to create a strong and rigid densified matrix of the fibers. The densified matrix had a compression strength of 101.7 MPa and remained stable upto 100 °C. Such densified materials can be used for packaging applications or as one of the components of vegan leather. The onion waste and densified material were characterized using FTIR, XRD, SEM imaging, elemental analysis, and compression testing to identify the structure-property relationship.