Search Results (3,040)

To meet 2050 climate targets, the construction sector must reduce CO₂ emissions and transition toward circular material flows. Recycled aggregates (RA) derived from construction and demolition waste (CDW) and industrial byproducts such as oil shale ash (OSA) show potential for use in concrete, although their application remains limited by standardisation and performance limitations, particularly in structural uses. This study aims to develop and evaluate low-strength, resource-efficient concrete mixtures with full replacement of natural aggregates (NA) by CDW-derived aggregates, and partial or full replacement of cement CEM II by OSA–metakaolin (MK) binder, targeting non-structural 3D-printing applications. Mechanical performance, printability, cradle-to-gate life cycle assessment, eco-intensity index, and transport-distance sensitivity for RA were assessed to quantify the trade-offs between structural performance and global warming potential (GWP) reduction. Replacing NA with RA reduced compressive strength by ~11–13% in cement-based mixes, while the aggregate type had a negligible effect in cement-free mixtures. In contrast, full cement replacement by OSA-MK binder nearly halved compressive strength. Despite the strength reductions associated with the use of waste-derived materials, RA-based cement-free 3D-printed specimens achieved ~30 MPa in compression and ~5 MPa in flexure. Replacing CEM II with OSA-MK and NA with RA lowered GWP by up to 48%, with trade-offs in the air-emission, toxicity, water and resource categories driven by the OSA supply chain. The cement-free RA mix achieved the lowest GWP and best eco-intensity, whereas the CEM II mix with RA offered the most balanced multi-impact profile. The results show that regionally available OSA and RA can enable eco-efficient, structurally adequate 3D-printed concrete for construction applications. Full article

Glass wool waste constitutes a rapidly increasing fraction of construction and demolition residues, yet it remains one of the most challenging insulation materials to recycle. Its non-combustible nature, extremely low bulk density, and high fibre elasticity preclude energy recovery and severely limit conventional mechanical recycling routes, resulting in long-term landfilling and loss of mineral resources. Converting glass wool waste into a fine mineral powder represents a potentially viable pathway for its integration into low-carbon construction materials, provided that industrial scalability, particle-size control, and chemical compatibility with cementitious binders are ensured. This study investigates the industrial-scale milling of end-of-life glass wool waste in a ventilated horizontal ball mill. It compares two grinding routes: a corundum-free route (BK) and an abrasive-assisted route (ZK) employing α-Al₂O₃ corundum to intensify fibre fragmentation. Particle size distribution was quantified by laser diffraction using cumulative and differential analyses, as well as characteristic diameters. The results confirm that abrasive-assisted milling significantly enhances fragmentation efficiency and reduces the coarse fibre fraction. However, the study demonstrates that this gain in fineness is inherently coupled with the incorporation of α-Al₂O₃ into the milled powder, introducing a chemically foreign crystalline phase that cannot be removed by post-processing. From a cement-oriented perspective, this contamination represents a critical limitation, as α-Al₂O₃ may interfere with hydration reactions, aluminate–sulfate equilibria, and microstructural development in Portland and calcium sulfoaluminate binders. In contrast, the corundum-free milling route yields a slightly coarser, chemically unmodified powder, offering improved process robustness, lower operational complexity, and greater compatibility with circular economy objectives. The study establishes that, for the circular reuse of fibrous insulation waste in cementitious systems, particle fineness alone is insufficient as an optimization criterion. Instead, the combined consideration of fineness, chemical purity, and binder compatibility governs the realistic and sustainable reuse potential of recycled glass wool powders. Full article

The progressive depletion of natural aggregate resources and the increasing emphasis on sustainable construction practices have intensified interest in incorporating recycled concrete aggregate (RCA) into cement-based materials. This study provides a comprehensive evaluation of the influence of partially replacing natural fine aggregate with fine RCA on the physical, mechanical, and durability properties, as well as the microstructure, of cement mortars. Mortar mixtures containing 25%, 50%, 75%, and 100% RCA were tested and compared with a reference mix MC. The experimental program included measurements of bulk density, compressive and flexural strength, water absorption, and freeze–thaw resistance. Additionally, microstructural observations were performed to assess the effect of RCA on the internal structure of matured mortars. The results demonstrated that the intrinsic characteristics of RCA—particularly its higher water absorption and lower density—significantly affected the pore structure and mechanical behavior of the cement mortars. Mortars with RCA exhibited enhanced early-age compressive and flexural strength, especially at substitution levels of 50–100%, attributed to the activation of residual cement paste adhering to the recycled particles. However, increased porosity and water absorption in RCA-based mixes led to a higher sensitivity to freeze–thaw cycles compared with the reference mix. Overall, the findings indicate that incorporating fine RCA up to 50% enables the production of mortars with performance comparable to conventional mixtures under non-freezing conditions, while, under freeze–thaw exposure, comparable performance is achieved at replacement levels up to 25%, contributing to improved resource efficiency and reduced environmental impact. This study confirms the viability of fine RCA in cement mortars, emphasizing the importance of controlling pore structure development to maintain long-term durability. Additionally, it demonstrates that the use of recycled concrete aggregates provides a sustainable alternative to natural sand in mortar production. Full article

Artificial reefs are an important tool for marine ecological restoration and fishery resource proliferation, and are widely used around the world. Among them, Japan, the United States, China, South Korea, Australia, and the Mediterranean coastal countries have particularly invested in scientific research and practice in this field, and the reefs’ material selection, structural performance, and ecological benefits have attracted much attention. The purpose of this paper is to summarize the preparation methods, characterization methods (such as microstructure analysis and mechanical tests) and mechanical properties (such as compressive strength and durability) of new concrete materials (steel slag-blast furnace slag concrete, oyster shell concrete, sulfoaluminate cement concrete, recycled brick concrete, silica fume concrete, and banana peel filler concrete) that artificial reefs and ceramic artificial reefs developed in recent years, and to explore the resource utilization potential of different waste materials. At the same time, the biostatistical methods (such as species abundance and community diversity) of wood, shipwreck, steel, rock, waste tire, and ordinary concrete artificial reefs and their effects on the marine environment were compared and analyzed. In addition, the potential impact of artificial reef deployment on local fishermen’s income was also assessed. It is found that the use of steel slag, blast furnace slag, sulfoaluminate cement, and silica fume instead of traditional Portland cement can better improve the mechanical properties of concrete artificial reefs (compressive strength can be increased by up to 20%) and reduce the surface pH to neutral, which is more conducive to the adhesion and growth of marine organisms. The compressive strength of oyster shell concrete and banana peel filler concrete artificial reef is not as good as that of traditional Portland cement concrete artificial reef, but it still avoids the waste of a large amount of solid waste resources, provides necessary nutritional support for aquatic organisms, and also improves its chemical erosion resistance. The deployment of artificial reefs of timber, wrecks, steel, rock, waste tires, and ordinary concrete has significantly increased the species richness and biomass in the adjacent waters and effectively promoted the development of fisheries. Cases show that artificial reefs can significantly increase fishermen’s income (such as an increase of about EUR 13 in the value of a unit effort in a certain area), but the long-term benefits depend on effective supervision and community co-management mechanisms. This paper provides a scientific basis for the research and development of artificial reef materials and the optimization of ecological benefits, and promotes the sustainable development of marine ecological restoration technology and fishery economy. Full article

The aquatic plant family Lemnaceae, commonly called duckweed or water lentil, has attracted increasing interest in the scientific literature over the past two decades. It holds extraordinary potential as a new crop due to its multiple applications: as an alternative protein source for feed and food production, as a starch producer for renewable biofuel, and for its capacity to provide valuable ecosystem services. Its high biomass productivity, ability to thrive under a wide range of environmental conditions, lack of requirement for arable land, and aptitude for nutrient recycling from wastewater align with the criteria for future sustainable crops. The Lemnaceae is a small plant family comprising a still uncertain number of species and hybrids with largely unexplored genetic diversity, owing to its taxonomic complexity. We focus on critical aspects that must be addressed to establish duckweed as a viable crop: the availability and accessibility of genomic resources to understand the genetic basis of key agronomic traits; the development of protocols for flower induction and crossing; and the establishment of effective methods for genetic transformation and plant regeneration, all aimed at enabling selection and breeding strategies. We highlight the importance of duckweed germplasm collections, including accessions from a wide geographic and ecological range, as essential resources for addressing duckweed diversity and supporting both fundamental research and agronomic applications. Full article

Wastewater treatment is one of the major challenges in the reuse of water as a natural resource. Cleaning of water depends on analyzing and treating the water for the pollutants that have a significant impact on the quality of the water. Detecting and analyzing the surges of these pollutants well before the recycling process is needed to make intelligent decisions for water cleaning. The dynamic changes in pollutants need constant monitoring and effective planning with appropriate treatment strategies. We propose an edge-computing-based smart framework that captures data from sensors, including ultraviolet, electrochemical, and microfluidic, along with other significant sensor streams. The edge devices send the data from the cluster of sensors to a centralized server that segments anomalies, analyzes the data and suggests the treatment plan that is required, which includes aeration, dosing adjustments, and other treatment plans. A logic layer is designed at the server level to process the real-time data from the sensor clusters and identify the discharge of nutrients, metals, and emerging contaminants in the water that affect the quality. The platform can make decisions on water treatments using its monitoring, prediction, diagnosis, and mitigation measures in a feedback loop. A rule-based Large Language Model (LLM) agent is attached to the server to evaluate data and trigger required actions. A streamlined data pipeline is used to harmonize sensor intervals, flag calibration drift, and store curated features in a local time-series database to run ad hoc analyses even during critical conditions. A user dashboard has also been designed as part of the system to show the recommendations and actions taken. The proposed system acts as an AI-enabled system that makes smart decisions on water treatment, providing an effective cleaning process to improve sustainability. Full article

Intensive agriculture, ecosystem degradation, and declining soil quality highlight the urgent need for sustainable land use strategies. The cultivation of short-rotation woody crops (SRC), combined with fertilization using sewage sludge digestate (SSD), offers a promising approach to recycle nutrient-rich waste and promote soil organic carbon (SOC) accumulation. This study evaluated SOC concentrations, stocks and their spatial distribution in the 0–20 cm soil layer under SRC cultivation, with and without SSD fertilization, across contrasting soil types in Eastern Lithuania. The investigated soils included mineral (Luvisols (LV), Retisols (RT), Planosols (PL), Arenosols (AR)), organo-mineral (Gleysols (GL)), and organic soils (Histosols (HS)), representing textures from sand to peat and classified according to the World Reference Base for Soil Resources (WRB). Part I assessed baseline SOC variability in unproductive areas planted with hybrid poplars (Populus spp.) and hybrid aspen (Populus tremula × P. tremuloides) up to 20 years old. Part II examined SOC changes in three SRC fields of different ages (3–10 years), including unfertilized and SSD-fertilized stands. SOC concentrations increased consistently from mineral (1.14–1.80%) to organo-mineral (2.13–3.20%) and organic soils (6.37–17.53%). Heavier-textured soils accumulated more SOC than lighter soils, showing a strong positive correlation between SOC and soil texture (r = 0.82, p ≤ 0.01). SRC cultivation increased SOC across all soil types, while SSD fertilization further enhanced accumulation, with fertilized fields showing SOC increases of 0.50–1.07 percentage points and carbon stocks by 18.8–41.7 t ha⁻¹, compared with smaller increases in unfertilized fields. Spatial visualization of SOC further highlighted long-term accumulation patterns across soil types, confirming the trends observed under SRC cultivation and SSD fertilization. Full article

Urban leaf litter represents an underutilized biomass resource with potential applications in sustainable building materials. This study investigates the suitability of dried, comminuted leaves collected from municipal green areas as a loose-fill thermal insulation material. The material was characterized in terms of thermal conductivity, settlement behavior, fire reaction, resistance to mold growth, water vapor diffusion, hygroscopic sorption, and short-term water absorption. Tests were conducted following relevant DIN and ISO standards, with both untreated and flame-retardant-treated samples examined. Results indicate that the thermal conductivity of leaf-based insulation (λ = 0.041–0.046 W/m·K) is comparable to other bio-based loose-fill materials such as cellulose and wood fiber. Optimal performance was achieved for particles sized 2–16 mm, showing settlement below 1%. All variants, including untreated material, fulfilled the fire resistance requirements of class E, while selected treatments further improved fire resistance. The material exhibited moderate vapor permeability (μ ≈ 4–5), low water absorption, and moisture buffering behavior similar to that of other bio-based insulation materials. Resistance to mold growth was satisfactory under standardized conditions. Overall, the results demonstrate that leaf litter can serve as an effective and environmentally favorable loose-fill insulation material, offering an innovative recycling pathway for urban green waste. Full article

Copper is a strategic raw material and an important component in electric motors, widely used across industries because of its excellent conductivity and recyclability. It plays an important role in the transformation from fossil fuel-based systems to green, electrified systems. However, substantial material losses continue throughout the lifecycle of electric motors, even with copper’s intrinsic capacity for circularity. Also, copper’s increasing demand, which is driven by the emergence of electric vehicles, industrial electrification, and renewable energy infrastructure, poses questions regarding its sustainable supply. The recovery of secondary copper sources from end-of-life (EoL) products is becoming more and more important in this context. However, it is still difficult to achieve circularity of copper, especially from industrial electric motors. This study investigates the challenges of closing the loop for copper during the lifecycle of motors in industrial applications. Based on an examination of EoL strategies, material flow insights, and practical investigation, the research pinpoints significant inefficiencies in the current processes. The widespread use of scraping as an approach of end-of-life management is one significant issue. Most of the electric motors are not built to separate their components, which makes both mechanical and manual disassembly difficult. The quality of recovered copper is thus compromised by the dominance of mixed metal shredding methods in the recycling step. This study highlights the need for systemic changes in addition to technical solutions to address copper circularity issues. It requires a focus on circularity in designing, giving disassembly and metal recovery a priority. This study focuses on circularity and its technological challenges in a value chain of copper. It not only identifies different processes such as supply chain disconnections and design constraints, but it also suggests workable solutions to close the copper flow loop in the electric motor sector. Copper quality and recovery is ultimately a problem involving design, technology, and cooperation, in addition to resources. This study supports the transition to a more sustainable and circular electric motor industry by offering a basis for directing such changes in industry practices and prospective EU regulations. Full article

This study contributes to the advancement of circular economy practices in polymer manufacturing by applying machine learning algorithms (MLA) to predict the tensile strength of recycled low-density polyethylene (LDPE) building films. As the construction and packaging industries increasingly seek eco-efficient and low-carbon materials, recycled LDPE offers a valuable route toward sustainable resource management. However, ensuring consistent mechanical performance remains a challenge when reusing polymer waste streams. To address this, tensile tests were conducted on LDPE films produced from recycled granules, measuring tensile strength, strain, mass per unit area, thickness, and surface roughness. Three established machine learning algorithms—feed-forward Neural Network (NN), Gradient Boosting Machine (GBM), and Extreme Gradient Boosting (XGBoost)—were implemented, trained, and optimized using the experimental dataset using R statistical software (version 4.4.3). The models achieved high predictive accuracy, with XGBoost providing the most robust performance and the highest level of explainability. Feature importance analysis revealed that mass per unit area and surface roughness have a significant influence on film durability and performance. These insights enable more efficient production planning, reduced raw material usage, and improved quality control, key pillars of sustainable technological innovation. The integration of data-driven methods into polymer recycling workflows demonstrates the potential of artificial intelligence to accelerate circular economy objectives by enhancing process optimization, material performance, and resource efficiency in the plastics sector. Full article

The increasing demand for sustainable polymer composites has driven the development of hybrid laminates that combine natural, recycled, and synthetic reinforcements while maintaining adequate mechanical performance. However, the combined influence of stacking sequence and mineral filler addition on the mechanical behavior of such sustainable hybrid systems remains insufficiently understood. In this study, sustainable hybrid laminated composites based on epoxy reinforced with glass fiber (G), bamboo fiber (B), and flex banner (F) were fabricated with varying stacking sequences and calcium carbonate (CaCO₃) filler contents (0 and 1 wt.%). A total of nine laminate configurations were produced and evaluated through flexural and impact testing. The results demonstrate that mechanical performance is strongly governed by laminate architecture and filler addition. The bamboo-dominant G/B/B/B/G laminate containing 1 wt.% CaCO₃ exhibited the highest flexural strength (191 MPa) and impact resistance (0.766 J/mm²), indicating a synergistic effect between reinforcement arrangement and CaCO₃-induced matrix strengthening. In contrast, the lowest performance was observed for the G/F/B/F/G configuration without filler. Overall, all hybrid composites outperformed neat epoxy, highlighting the potential of bamboo–flex banner hybrid laminates with CaCO₃ filler for sustainable composite applications requiring balanced mechanical properties. This work aligns with SDG 12 by promoting resource-efficient circular-economy practices through the utilization of flex banner material and natural fibers as reinforcements in epoxy-based hybrid composites. Full article

This study evaluates the environmental outcomes of integrating anaerobic digestion (AD) with pyrolysis (Py) and hydrothermal carbonization (HTC) to treat cattle slurry and grass silage in an Irish agricultural context. A consequential life cycle assessment (CLCA) was carried out for six scenarios based on 1 t of feedstock (0.4:0.6 cattle slurry/grass silage on a VS basis): two standalone AD systems (producing bioelectricity and biomethane) and four integrated AD–Py/HTC systems with different product utilisation pathways. Across all impact categories, the integrated systems performed better than standalone AD. This improvement is mainly due to the surplus bioenergy (electricity, biomethane, hydrocarbon fuel, hydrochar) that replaces marginal fossil energy (hard coal, natural gas and heavy fuel oil), together with the displacement of mineral NPK fertilisers by digestate-derived biochar and HTC process water. Among the configurations, the AD–HTC bioelectricity scenario (S4) achieved the best overall performance, driven by higher hydrochar yields, a favourable heating value, and a lower pretreatment energy demand compared with Py-based options. Across the integrated scenarios, climate change, freshwater eutrophication, and fossil depletion impacts were reduced by up to 84%, 86%, and 99%, respectively, relative to the fossil-based reference system, while avoiding digestate and fertiliser application reduced terrestrial acidification by up to 74%. Overall, the results show that the cascading utilisation of digestate via AD–Py/HTC can simultaneously enhance bioenergy production and nutrient recycling, providing a robust pathway for low-emission management of agricultural residues. These findings are directly relevant to Ireland’s renewable energy and circular economy targets and are transferable to other livestock-intensive regions seeking to valorise slurry and grass-based residues as low-carbon energy and biofertiliser resources. Full article

With the depletion of natural sand and gravel resources and increasing emphasis on environmental protection, natural aggregates suitable for concrete production are becoming increasingly scarce. Steel slag, a by-product of steelmaking, is produced in substantial quantities yet remains underutilized due to its low recycling rate. Owing to the high strength and excellent compatibility of steel slag particles with cementitious materials, they demonstrate significant potential as a replacement for natural river sand in fine aggregate applications. However, the volumetric instability of steel slag has long been a major impediment to its widespread adoption in cement-based composites. This study examines the stability performance of cement mortar containing steel slag aggregate, with the objective of clarifying the mechanisms responsible for dimensional instability resulting from steel slag incorporation. When the replacement level exceeds 40%, the dimensional stability of the mortar deteriorates markedly. The initial contents of free CaO (f-CaO) and free MgO (f-MgO) in the steel slag were determined to be 1.58% and 1.14%, respectively. Following 50 h of hydrothermal treatment, 69.6% of f-CaO and 44.3% of f-MgO had hydrated, causing internal volumetric expansion and subsequent particle fracturing. Under elevated temperature conditions, over-burned lime demonstrated 220% volumetric expansion and completed its reaction within 40 min, consequently impairing early-age stability. In contrast, periclase (dead-burned MgO) exhibited 34% expansion and attained a reaction degree of merely 13.3%, suggesting a more substantial impact on long-term stability. For each mixture, linear expansion measurements were performed on n = 5 independent specimens, and results are reported as mean ± standard deviation. Full article

The maritime transport sector’s reliance on fossil-based fuels remains a major contributor to global greenhouse gas emissions, underscoring the urgent need for sustainable alternatives such as marine biofuels. Thermochemical pyrolysis of biomass and plastic waste represents a promising route for producing renewable and recycled marine fuel feedstocks. This review provides an integrated analysis of the full production and upgrading chain, encompassing pyrolysis of lignocellulosic biomass and polymer-derived resources, catalytic upgrading, and qualitative evaluation of product distribution and yield trends. Particular emphasis is placed on montmorillonite-based catalysts as naturally abundant, low-cost, and environmentally benign alternatives to conventional zeolites. The review systematically examines the influence of key montmorillonite modification strategies, including acid activation, pillaring, and ion-exchanged, on acidity, textural properties, and catalytic performance in catalytic cracking and hydrodeoxygenation processes. The analysis shows that catalyst modification strongly governs the yield, selectivity, and reproducibility of biofuels. By adopting this integrated perspective, the review extends beyond existing works focused on isolated upgrading steps or zeolitic catalysts. Key research gaps are identified, particularly regarding long-term catalyst stability, deep deoxygenation of real bio-oils, and compliance with marine fuel standards. Full article

The increasing environmental impact of the textile industry has led to the development of sustainable production methods. One of the effective approaches is the use of recycled fibers, which helps to save resources, reduce carbon emissions, and support the circular economy. This study investigates the feasibility of producing durable upholstery fabrics incorporating recycled polypropylene (r-PP) and virgin polypropylene (v-PP). Filament yarns with varying r-PP/v-PP blend ratios, produced by the melt spinning process, were used as weft yarns, while commercially available virgin polyester filament yarns were employed in the warp direction for all fabric samples. Performance tests in accordance with the standards were applied to the fabrics and the results were also evaluated statistically. The results show that acceptable performance is achieved in some mechanical properties if similar blend ratios and production parameters are used. In the study, an optimization model was developed to maximize the weft breaking strength using the equations obtained from the regression analyses. With the help of the mathematical model created, the values of other physical and performance properties of the fabric depending on the maximum breaking strength value could be estimated without the need for trial production. The model was solved using Lingo 18.0 optimization software. The solution of the model revealed that the optimum weft yarn blend ratio is 10/90 r-PP/v-PP, and the maximum weft breaking strength value is 562.45 N. Full article