Search Results (409)

The sustainable application of ultra-high-performance concrete (UHPC) is often constrained by high material costs and environmental footprints. While the individual effects of various industrial wastes have been extensively studied, the synergistic mechanism of multi-source waste in UHPC remains poorly understood. To fill the research gap, an eco-UHPC was developed wherein river sand (RS) was partially replaced by spontaneous combustion gangue sand (SCGS), and Portland cement (PC) was partially replaced by spontaneous combustion gangue (SCG) powder and phosphorous slag (PS). A systematic investigation was conducted to assess the packing density, flowability, mechanical properties, chloride ion penetration resistance, and micromorphology. The results indicate that 40% SCGS substitution (by mass) optimizes particle packing density and aggregate gradation, while PS incorporation significantly improves flowability by up to 16.83%. Notably, persistent pozzolanic reactions and the consumption of Ca(OH)₂ facilitate the generation of dense C-S-H gel, which creates a uniform microstructure and enhances late-stage compressive strength. Furthermore, superior chloride penetration resistance is achieved when the PS content is maintained below 20%. These findings support the synergistic utilization of SCGS, SCG, and PS in UHPC production, while facilitating broader application of UHPC through reduced costs and lower carbon emissions. Full article

This study investigates the combined effect of incorporating recycled concrete aggregates (RCAs) and glass fibers (GFs) on the properties of geopolymer concrete. The precursor binder consisted of a blend of ground granulated blast furnace slag and fly ash. Furthermore, two types of GFs (i.e., short and long) were incorporated, either individually or in hybrid combinations, to enhance the performance of the concrete. Experimental results revealed that replacing natural aggregates (NAs) with RCAs in geopolymer concrete production had no tangible impact on workability but resulted in a slight reduction in the density, ultrasonic pulse velocity, and bulk resistivity. Similarly, the compressive strength and modulus of elasticity decreased by up to 18 and 57%, respectively. Meanwhile, the addition of GFs, particularly in hybrid configurations, effectively mitigated these reductions. Among the hybrid mixtures, a short-to-long fiber ratio (A:B) of 1:3 yielded the most significant improvements of the physical, mechanical, and durability properties, with increases of up to 16%, 91%, and 61%, respectively. Several correlation equations were established to describe the relationships between the physical, mechanical, and durability properties of GF-reinforced geopolymer concrete and were compared with existing codified models. The outcomes provide critical insights into the synergistic roles of RCA and GFs in tailoring high-performance, eco-efficient concrete systems. This research supports the advancement of sustainable concrete production and promotes the broader structural adoption of geopolymer technologies. Full article

Host alternation is a common behavioral strategy among many herbivorous insects. The mulberry longhorn beetle, Apriona germari is a destructive wood-boring pest. The adults exhibit rhythmic host alternation between feeding and oviposition hosts. However, the temporal rhythm and regulatory mechanisms underlying this behavior remain unclear. In the present study, by observing the dynamics of the numbers of A. germari on mulberry (Morus alba, feeding host) and willow (Salix babylonica, oviposition host) trees in a cage, we first found that both females and males began to aggregate on mulberry trees at dawn. Following 18:00 at dusk, the number of females on mulberry declined sharply, whereas the number of males decreased slightly, with a greater proportion of males staying on mulberry. To investigate the role of host volatiles in regulating the host alternation in A. germari, we then carried out two-choice olfactory assays to test whether the behavioral responses of A. germari to the host volatiles from mulberry and willow twigs differed between 04:00 and 08:00 (dawn, aggregated on mulberry) and 18:00 to 22:00 (dusk, dispersed from mulberry). Males were consistently attracted to the volatiles from healthy mulberry at both dawn and dusk, but not to those from willow. Females showed no attraction to the volatiles from either of two hosts at dawn; however, at dusk, they were significantly attracted to willow volatiles. Furthermore, volatiles from feeding-damaged mulberry trees were repellent to both sexes, particularly to males at dawn. These results indicate that the rhythmic host alternation in A. germari is partly mediated by host volatiles and an unidentified male-produced pheromone may be present in this species. Our findings can deepen the understanding of the host alternation in longhorn beetles, and offer a theoretical foundation for developing semiochemical-based, eco-friendly strategies for controlling this pest. Full article

The study focuses on the attempt to produce structural concrete, class C25/30 with exposure class XC3, using recycled aggregates derived from Excavation, Construction and Demolition Waste (ECDW) management. All the necessary properties of the recycled aggregates used were determined and four concrete mix compositions were made with recycled aggregate percentages ranging from 25% to 100%, while two more mix compositions were made with natural aggregates (NAs) to compare the results. A total of 78 cubic specimens, 13 from each mix, were obtained and their compressive strength, dynamic modulus of elasticity, rebound number, maximum deformation and maximum mass loss due to evaporation were determined at ages of 3, 7, 14, 28 and 90 days. The results show that 25–50% replacement with mixed recycled aggregates can satisfy the C25/30 strength class, whereas 100% replacement leads to significant strength and stiffness reductions. Overall, the study demonstrates that structural-grade recycled aggregate concrete is feasible up to moderate replacement levels, provided that the high water absorption and increased deformability associated with recycled aggregates are explicitly accounted for in mix design, curing and serviceability checks. Full article

Environmental concerns associated with the construction industry have drawn increasing attention worldwide. This study addresses the dual challenges of carbon emissions from cement production and construction waste disposal by developing and characterizing a fiber-modified geopolymer recycled aggregate porous concrete (GRAPC). An orthogonal experiment first optimized the GRAPC mix proportion (slag content = 40%, alkali modulus = 1.4, alkali content = 8%). Subsequently, the effects of coir, basalt, and steel fibers (0.25% and 0.5%) on its properties were investigated through laboratory experiments combined with scanning electron microscopy (SEM) analysis. The results show that steel fibers at 0.25% dosage enhanced compressive strength by approximately 25% due to their effective stress-bearing capacity. In contrast, 0.5% coir and basalt fibers reduced compressive strength by approximately 20.5% and 22.2%, respectively, due to low intrinsic strength and agglomeration. In addition, 0.25% coir and steel fibers increased effective porosity by 18.4% and 17.4%, respectively, owing to their uniform dispersion. All fibers promoted a more ductile-like failure mode, with coir fibers providing the best toughness improvement. This study elucidates how fiber type and dosage regulate the macro-properties and micro-mechanisms of GRAPC, providing a basis for designing sustainable eco-friendly concrete with great potential for non-primary load-bearing engineering fields. Full article

The increasing demand for civil infrastructure has contributed significantly to CO₂ emissions and global warming potential (GWP), largely due to concrete production, cement manufacturing, and natural aggregate extraction. Automotive shredder residue (AutoSR) offers a sustainable alternative; however, its effects on concrete performance remain poorly understood. This study evaluates AutoSR fines, termed eco-friendly aggregates (EFAs), used at 10% volumetric replacement for natural fine aggregate in eight concrete mixtures. Fresh and hardened properties were assessed for EFAs with varying particle characteristics. Microstructural features, including the interfacial transition zone (ITZ), and maturity indicators based on the temperature–time factor (TTF) and ultrasonic pulse velocity (UPV) were examined. All EFA mixtures showed reduced workability compared to the control mix, while hydration behavior and UPV responses remained comparable, allowing the development of maturity master curves. Mechanical performance was strongly influenced by EFAs’ characteristics, with an increased ITZ thickness identified as the primary driver of strength reduction. The study establishes a clear mechanistic link between EFA absorption, ITZ development, and strength loss, supporting a practical 10% replacement level for structural applications and providing guidance for future optimization. The potential economic benefits are also briefly discussed. Full article

Vegetation eco-concrete (VEC) is a novel material for slope stabilization, effectively integrating ecological restoration with engineering protection. Its primary supporting skeleton consists of aggregates with specific particle sizes, bonded by cementitious materials, and is characterized by numerous interconnected pores, along with certain mechanical properties. However, VEC still faces challenges in practical application, such as inaccuracies in the optimal mix design and poor vegetative compatibility between the structural material and plants. To determine the optimal mix for porous VEC, this study utilizes Portland cement to design the VEC mix proportions based on orthogonal tests. The study further conducts VEC paving and plant experiments based on the optimal mix obtained. The results indicate the following: (1) The optimal mix consists of a water–cement ratio of 0.27, a cement particle diameter of 10 mm, a cement particle content of 70–75 wt%, a mortar binder content of 0.1 wt%, and a polypropylene fiber content of 0.16 wt%. (2) VEC with nutrient-enriched particles exhibited excellent vegetative compatibility, providing root penetration channels and creating a conducive environment. (3) Plant species with strong adaptability and well-developed root systems that integrate with VEC can enhance both the engineering protection and ecological benefits of VEC. Full article

Drifting fish aggregating devices (DFADs) are central to tropical tuna purse-seine fisheries, yet their hydrodynamic performance under realistic seas has not been adequately addressed, particularly for emerging eco-friendly designs. A three-dimensional framework based on computational fluid dynamics is developed to assess the motion response and mooring loads of full-scale DFADs comprising raft buoys, biodegradable cotton rope, and iron sinkers, using four buoy layouts (Models A to D). Unsteady Reynolds-averaged Navier–Stokes (URANS) simulations are performed with a realizable k–ε closure, volume of fluid (VOF) free-surface capturing, the Euler overlay method, dynamic overset meshes, and catenary mooring coupling. Regular waves representative of operational conditions (T = 1.40 to 2.40 s, H = 0.10 to 0.40 m) are imposed via a VOF wave-forcing technique, and mesh/time-step sensitivity analyses demonstrate the accurate reproduction of the first-order wave elevation (error < 0.8%). Surge drift per cycle and heave response amplitude operators, with the relative mooring force, are evaluated as functions of the relative wavelength (λ/L_a) and wave steepness (H/λ). The results reveal that the buoy layout exerts first-order control on DFAD dynamics, whereas short, steep waves dominate motion and line loads. The intermediate end-point sinker mass achieves a favorable balance between motion suppression and mooring load control, whereas distributing a fixed total sinker mass along the rope reduces heave response and mooring force by improving the tension redistribution and overall stability. Across all sea states, Models A and D reduced motion envelopes and mooring forces, indicating their suitability as robust, low-impact configurations. The proposed framework and design recommendations provide quantitative guidance for optimizing eco-DFAD geometry and deployment strategies, supporting safer and more sustainable DFAD-based tuna fisheries. Full article

This study investigates an eco-friendly rapid-setting concrete developed for emergency repair and accelerated post-disaster reconstruction. The proposed material concept combines a low-emission multicomponent cement, CEM V/A (S-V) 42.5 N-LH/HSR/NA, with a hybrid aggregate skeleton composed of crushed granite and waste soda–lime glass, as well as a waste-derived silicate additive system based on aqueous sodium silicate, glass dust and glass powder. One reference mixture (R) and five modified mixtures (M1–M5) were designed to assess the effects of partial replacement of natural aggregate by glass aggregate and of the dosage of the silicate-based additive system on concrete performance. The experimental programme included setting time, compressive strength, splitting tensile strength, water absorption, freeze–thaw resistance and microstructural observations. Among the modified concretes, the mixture containing 5 vol.% glass aggregate (M1) showed the most favourable mechanical performance after 28 days, reaching a compressive strength of 95.1 ± 2.4 MPa and a splitting tensile strength of 4.82 ± 0.29 MPa, compared with 45.5 ± 0.8 MPa and 2.18 ± 0.11 MPa, respectively, for the reference concrete. Higher glass contents reduced strength relative to M1, but the modified mixtures still maintained satisfactory performance. The silicate-based system significantly affected setting behaviour; in mixture M5, the initial and final setting times were reduced from 380 ± 5 min and 497 ± 5 min to 213 ± 5 min and 307 ± 5 min, respectively. The results show that the combined use of CEM V cement, waste glass and silicate-based waste-derived additives can produce concretes with rapid-setting, high strength and satisfactory durability-related properties. The developed material may therefore be considered a promising solution for selected rapid-repair and reconstruction applications, particularly in lightly reinforced or unreinforced concrete elements requiring fast restoration of functionality. Full article

This study investigates the application of artificial intelligence for predicting the compressive strength of a high-performance, eco-efficient engineered cementitious composite (ECC), designated mix S8-1, A. The composite incorporates supplementary cementitious materials and alternative aggregates derived from recycled glass waste. The binder system combines waste glass powder and silica fume, while the aggregate fraction includes recycled cobalt glass. An extensive experimental program involving 14 mixtures tested at 7, 28, 56, 90, and 120 days was performed to establish the reference mechanical and rheological properties. Mix S8-1, A achieved strength class C60/75 and workability corresponding to consistency class S4. To substantiate long-term performance, microstructural and chemical analyses were conducted on specimens preserved since 2011, using scanning electron microscopy (SEM) and X-ray fluorescence (XRF). The results confirmed a stable, densified microstructure, evidencing the long-term durability of the patented ECC formulation. For predictive modeling, a shallow feedforward artificial neural network with three hidden layers was developed and trained on 70 dataset entries representing mixture proportions and curing ages. Model performance was evaluated using cross-validation, achieving a coefficient of determination (R²) of 0.968, a mean absolute error of 1.96 MPa, and a root mean square error of 2.52 MPa. The results demonstrate that AI-based approaches can accurately predict the compressive strength of high-performance, environmentally sustainable ECCs incorporating recycled glass constituents, supporting both performance optimization and resource-efficient material design. Full article

The construction industry requires sustainable building materials to reduce its environmental impact. While using these materials in newly constructed structures primarily focuses on environmental benefits, their application in the protection of architectural heritage presents an additional requirement. These materials must be physically and chemically compatible with historical substrates to ensure the longevity of the structure. Therefore, developing eco-friendly and compatible restoration materials is a significant concern. This study aims to produce artificial aggregates to develop lightweight concrete for structural interventions and reduce natural resource consumption (i.e., minimizing the destructive extraction of natural river sand and crushed stone aggregates). Magnesium-based binders were used to mimic the carbonation process of historical lime mortars. The binders were mixed with water, shaped into coarse pellets, and cured in a ${CO}_2$ incubator for 3 and 14 days before being used in concrete production. The results show that using artificial aggregates decreased the concrete density by approximately 16.5%. Since reducing the dead load improves the seismic safety of historical masonry structures, this reduction is critical. Although the compressive strength decreased compared to natural aggregate concrete, the 14-day cured series achieved a strength of 34.7 MPa. This demonstrates that the material can be used in restoration interventions where stiffness compatibility is essential (e.g., vault infills, ring beams, or floor screeds). At the same time, since magnesium-based artificial lightweight pellets have ${CO}_2$ sequestration capacity, they can be used as a carbon-negative solution for both historical structures and broader civil infrastructure. Full article

The demand for concrete has led to increased use of raw materials and significant waste generation. Recycled aggregate concrete (RAC) offers a viable approach to sustainable concrete; however, the use of weakly bonded mortar on aggregate leads to low strength and crack formation. Fiber reinforcement, specifically hybrid fiber reinforcement combining steel, glass, basalt, and polypropylene fibers, can increase the tensile and flexural properties of RAC. This study developed machine learning models to enable the prediction of hybrid fiber-reinforced RAC’s compressive, splitting tensile, and flexural strength performance; these new models overcome the limitations of previous research, which relied on only one fiber type and regular methods of optimization. Two models (a deep neural network (DNN) and an XGBoost model) were trained and optimized using bald eagle search (BES), particle swarm optimization (PSO), and the Bayesian optimization (BO) algorithm to improve performance. Among the three optimization analyses, PSO-XGBoost achieved the highest accuracy for compressive strength and splitting tensile strength, while BES-XGBoost achieved the highest accuracy for flexural strength. The most significant influences on the compressive strength were curing age and silica fume, while the main drivers of splitting tensile strength and flexural strength were fiber volume and fiber characteristics. The use of SHAP-based methodology with a user-friendly interface further improved the design of RAC mixtures, reducing waste from raw materials, enhancing the structural performance of RAC, and enabling data-driven decision-making in the manufacturing of eco-friendly concrete products. Full article

Enhancing plant protein structure, functionality, and digestion-associated bioactivity is pivotal to advancing sustainable food applications. In this study, a controlled thermal treatment was applied to Xanthoceras sorbifolium seed meal protein (XSMP) to characterize alterations in structural features, functional performance, and digestion-related bioactivity. Structural analyses showed that moderate heating induced partial unfolding and disaggregation, leading to reduced particle size and improved colloidal stability, with optimal performance observed at 65 °C. Accordingly, foaming capacity and emulsifying activity index reached their highest values under moderate heat pretreatment (71.43% and 27.21 m²/g, respectively). Simulated in vitro gastrointestinal digestion revealed that moderate heat pretreatment enhanced protease accessibility and was associated with increased formation of low-molecular-weight fragments. As a result, digestion products from optimally treated XSMP exhibited significantly enhanced antioxidant activities during the intestinal phase, including higher reducing power, Fe²⁺-chelating capacity (up to 51.21%), and lipid peroxidation inhibition (82.83%). In contrast, insufficient unfolding at lower temperatures or excessive aggregation at higher temperatures reduced the susceptibility to digestive proteases and the associated functional performance. These findings demonstrate that controlled heat treatment provides a simple and eco-friendly strategy to enhance the functional potential of XSMP, supporting its application as a functional protein ingredient. Full article

This study investigates the feasibility of incorporating recycled concrete aggregate (RCA) as a full replacement for fine aggregate in high-performance concrete (HPC). Five mixtures containing 0%, 25%, 50%, 75%, and 100% RCA were experimentally evaluated. Hardened density, compressive strength, splitting tensile strength, flexural strength, water absorption, microstructure (SEM), and carbon footprint were analyzed. Results showed a near-linear density reduction of 5.8% at 100% RCA due to lower specific gravity and higher porosity of RCA. Mechanical performance decreased with RCA content: compressive strength reduced from 78 MPa to 53 MPa (−32%), splitting tensile strength from 6.2 to 4.2 MPa, and flexural strength from 7.6 to 5.0 MPa. Water absorption increased by 42%, indicating increased permeability. SEM analysis revealed a weakened and porous interfacial transition zone (ITZ) surrounding RCA particles, explaining strength reduction. Carbon footprint analysis showed a slight increase in emissions with RCA due to cement dominance and RCA processing energy. Results confirm that RCA enhances material circularity but introduces a performance–durability trade-off, requiring optimized mix design and SCM integration for structural applications. Full article

Green-synthesized metal nanoparticles are increasingly investigated for their antioxidative, antimicrobial, and stress-protective properties as eco-friendly and cost-effective alternatives to conventional chemical synthesis. Although agri-food wastes represent biomolecule-rich and sustainable resources, they remain less explored as biological matrices for green metal nanoparticle synthesis compared with plant and microbial extracts. The aim of this study was to optimize the synthesis and evaluate the bioactivity of silver nanoparticles derived from bergamot pomace, a polyphenol-rich agri-food waste. Synthesis parameters, including extract concentration, pH, extract-to-metal ratio, temperature, and reaction time, were optimized, and the nanoparticles were characterized by UV–Vis spectroscopy, dynamic light scattering, zeta potential analysis, and electron microscopy (TEM, STEM). ATR-FTIR and proteomic analyses were employed to investigate the molecular mechanisms involved in nanoparticle reduction, capping, and stabilization. The bergamot pomace-based silver nanoparticles exhibited a surface plasmon resonance peak at 430 nm, spherical morphology, good colloidal stability, and average diameters of 15–20 nm, without irreversible aggregation. A putative synthesis mechanism was proposed, involving Ag⁺ bioreduction mediated by polyphenols, ascorbic acid, and oxidoreductase-associated proteins, followed by stabilization through protein corona formation. Seed nanopriming assays on tomato and lettuce, together with in vitro antimicrobial tests against Pseudomonas syringae pv. tomato and Xanthomonas campestris pv. vesicatoria, demonstrated phytostimulatory and antimicrobial effects at very low nanoparticle concentrations. Overall, this study highlights bergamot pomace as a valuable resource for green silver nanoparticle synthesis, supporting its applicability in sustainable agriculture. Full article