Search Results (1,860)

The construction industry is a major contributor to environmental degradation, primarily due to the substantial volumes of construction waste (CW) generated on-site. As sustainability becomes a global imperative aligned with the UN 2030 Agenda, identifying and mitigating the root causes of CW is essential. This study adopts a cross-disciplinary approach to explore the drivers of CW and support more effective, sustainable waste reduction strategies. A systematic literature review was conducted to extract 25 key CW source factors from academic publications. These were analyzed using Social Network Analysis (SNA) to reveal their structural relationships and relative influence. The results indicate that the lack of structured on-site waste management planning, accumulation of residual materials, and insufficient worker training are among the most influential CW drivers. Comparative analysis with industry data highlights theoretical–practical gaps and the need for improved alignment between research insights and site implementation. This paper recommends the adoption of tiered waste management protocols as part of contractual documentation, integrating Building Information Modeling (BIM)-based residual material traceability systems, and increasing attention to workforce training programs focused on material handling efficiency. Future research should extend SNA frameworks to sector-specific waste patterns (e.g., pavement or demolition projects) and explore the intersection between digital technologies and circular economy practices. The study contributes to enhancing waste governance, promoting resource efficiency, and advancing circularity in the built environment by offering data-driven prioritization of CW sources and actionable mitigation strategies. Full article

The use of solid products deriving from the pyrolysis of wastes as potential substitute of traditional binders in asphalt preparation is investigated with the final goal of reducing production costs, preserving non-renewable resources, and promoting an effective resource use as well as recovery and recycling procedures, thus implementing a regenerative circular economy approach. Char derived from the pyrolysis of agricultural and aquaculture wastes has been explored as a novel alternative additive for asphalt production. Different feedstocks were used for the preparation of biochar by pyrolysis. The produced char samples, after an in-depth chemical and structural characterization, have been implemented in the preparation of asphalt mixtures, with their potential use as a binder evaluated by performing conventional rheological tests. To evaluate the potential anti-aging effect of char as an additive, bituminous formulations containing 3 to 6 wt.% char were subjected to short-term simulated aging using the Rolling Thin-Film Oven Test (RTFOT) method. The resulting mechanical properties were then assessed. The results indicate that the all the tested char samples have limited modifying properties towards the gel-to-sol transition temperature. Among the samples, lemon peel-derived char (LP-char) showed superior antioxidant properties against bitumen oxidative aging. This study suggests that certain chemical characteristics can serve as predictive indicators of antioxidant activity in biochars produced from biomass pyrolysis. Full article

The built environment represents a significant portion of global resource consumption and waste generation, underscoring the pressing necessity for innovative circular economy approaches in architecture. This paper presents the findings of a systematic literature review on six critical areas: circular economy, circularity indicators, design for adaptability, design for disassembly, life cycle assessment, and material and component reuse. The analysis revealed the emergent aspects of circular economy practices in architecture, emphasizing the preeminence of life cycle assessment (LCA) and material reuse. However, the authors observe a relative scarcity of focus on design-for-adaptability and circularity indicators, highlighting a gap to be addressed. The findings underline the need for unified assessment tools, supportive regulations, and collaborative frameworks that can enable the full potential of circular architecture. By harnessing innovative reuse strategies from deconstruction projects, the circular economy offers a transformative pathway towards reducing emissions and fostering regenerative practices that can enhance material and component recovery and significantly contribute to decarbonization and the realization of sustainable development goals. Full article

Decarbonizing air transport is a major challenge in the global energy transition since electrification is not yet feasible. Sustainable aviation fuel (SAF) is a promising solution because it can reduce CO₂ emissions without major infrastructure changes. This study proposes a decentralized model for producing SAF in Spain through the gasification of residual lignocellulosic biomass followed by a refinement process using Fischer–Tropsch (FT) synthesis. The model uses underexploited agricultural residues such as cereal straw, vine pruning, and olive pruning, converting them into syngas in medium-scale facilities situated near biomass sources. The syngas is then transported to a central upgrading unit to produce SAF compliant with ASTM D7566 standards. The following two configurations were evaluated: one with a single gasification plant and upgrading unit and another with three gasification plants supplying one central FT facility. Energy yields, capital and operational expenditures (CAPEX and OPEX), logistic costs, and the levelized cost of fuel (LCOF) were assessed. Under a conservative scenario using one-third of the available certain types of biomass from three regions of Spain, annual SAF production could reach 517.6 million liters, with unit costs ranging from 1.63 to 1.24 EUR/L and up to 47,060 tonnes of CO₂ emissions avoided per year. The findings support the model’s technical and economic viability and its alignment with circular economy principles and climate policy goals. This approach offers a scalable and replicable pathway for decarbonizing the aviation sector using local renewable resources. Full article

Rising global populations, infrastructural development, and rapid urbanization have heightened the reliance on a linear economy, resulting in severe environmental and human impacts. This crisis has triggered an urgent quest for sustainable and ecologically benign innovations, as outlined in the United Nations’ Sustainable Development Goals (SDGs). This review investigates the potential of sugarcane bagasse (SCB) as a promising feedstock for advancing circular bioeconomy initiatives in South Africa. It shows how this copious bioresource can be utilized to enhance the country’s biobased value chains by producing bio-commodities, such as biofuels and platform chemicals. The review also identifies the driving forces behind the circular bioeconomy model within the South African sugarcane industry. To achieve the circular bioeconomy, it outlines essential technological prerequisites, including critical pretreatment strategies and emerging bio-innovations necessary for the effective valorization of SCB. Furthermore, it showcases the R&D and commercial strides that have been achieved in South Africa. Finally, the study covers techno-economic studies that corroborate the economic viability of this domain. In conclusion, harnessing SCB not only presents a viable biorefinery pathway towards sustainable economic growth but also contributes to environmental preservation and social well-being, aligning with global sustainability imperatives. The successful integration of these innovative approaches could play a pivotal role in transforming the South African sugarcane industry into a continental leader in circular bioeconomy innovations. Full article

This study evaluated the feasibility of reusing abandoned copper mine tailings (Cu tailings) as a precursor in the production of fly-ash-based alkali-activated materials (FA-AAMs). Two formulations were developed by combining FA and Cu tailings with a mixture of sodium silicate and sodium hydroxide as alkaline activators at room temperature (20 °C). Formulation G1 consisted of 70% Cu tailings and 30% fly ash (FA), whereas G2 included the same composition with an additional 15% ordinary Portland cement (OPC). The materials were characterized using X-ray fluorescence (XRF), -X-ray diffraction (XRD), field emission scanning electron microscopy with energy-dispersive spectroscopy (FESEM-EDS), and particle size analysis. While FA exhibited a high amorphous content (64.4%), Cu tailings were largely crystalline and acted as inert fillers. After 120 days of curing, average compressive strength reached 24 MPa for G1 and 41 MPa for G2, with the latter showing improved performance due to synergistic effects of geopolymerization and OPC hydration. Porosity measurements revealed a denser microstructure in G2 (35%) compared to G1 (52%). Leaching tests confirmed the immobilization of hazardous elements, with arsenic concentrations decreasing over time and remaining below regulatory limits. Despite extended setting times (24 h for G1 and 18 h for G2) and the appearance of surface efflorescence, both systems demonstrated good chemical stability and long-term performance. The results support the use of Cu tailings in FA-AAMs as a sustainable strategy for waste valorization, enabling their application in non-structural and moderate-load-bearing construction components or waste encapsulation units. This approach contributes to circular economy goals while reducing the environmental footprint associated with traditional cementitious systems. Full article

The recycling and remanufacturing of end-of-life (EoL) electric vehicle (EV) batteries are urgent challenges for a circular economy. Disassembly is crucial for handling EoL EV batteries due to their inherent uncertainties and instability. The human–robot collaborative disassembly of EV batteries as a semi-automated approach has been investigated and implemented to increase flexibility and productivity. Unscrewing is one of the primary operations in EV battery disassembly. This paper presents a new method for the robotic unfastening and collecting of screws, increasing disassembly efficiency and freeing human operators from dangerous, tedious, and repetitive work. The design inspiration for this method originated from how human operators unfasten and grasp screws when disassembling objects with an electric tool, along with the fusion of multimodal perception, such as vision and touch. A robotic disassembly system for screws is introduced, which involves a collaborative robot, an electric spindle, a screw collection device, a 3D camera, a six-axis force/torque sensor, and other components. The process of robotic unfastening and collecting screws is proposed by using position and force control. Experiments were carried out to validate the proposed method. The results demonstrate that the screws in EV batteries can be automatically identified, located, unfastened, and removed, indicating potential for the proposed method in the disassembly of EoL EV batteries. Full article

Municipal sewage treatment plants generate significant amounts of polluting sludge, which demands innovative valorization approaches to support its sustainable recycling. This work aimed to evaluate the valorization potential of sludge from a municipal sewage treatment plant (STP) as an alternative raw material to traditional limestone in red wall tile formulations. For this purpose, four red wall tile formulations were performed with 0%, 5%, 10%, and 15% weight of STP sludge replacing traditional limestone. The tile formulations prepared by the dry process were characterized to determine their chemical and mineral compositions, thermal analysis, and sintering behavior. The red wall tile pieces were manufactured by pressing and firing at temperatures ranging from 1150 °C to 1180 °C. The effects of STP sludge incorporation and firing temperature on the densification behavior and technological properties were investigated. The results indicated that the STP sludge exhibited good chemical compatibility for use in red wall tile formulations. Water absorption values varied between 16.52% and 19.70%, indicating compliance with the red wall tile production (BIII group). These findings demonstrate the valorization potential of STP sludge in red wall tiles, which offers a relevant recycling option for the sanitation sector and the circular economy. Full article

The construction sector is under growing pressure to transition from linear, resource-intensive models to regenerative, circular practices. While Circular Economy (CE), Building Information Modelling (BIM), and Agile Project Management (APM) are each recognized for their potential to improve sustainability, their combined application in construction remains underexplored, particularly among small- and medium-sized enterprises (SMEs). In this study, we propose a conceptual framework integrating CE as a strategic objective, APM as the procedural methodology, and BIM as the digital enabler to foster circular practices in construction. Unlike previous studies, this research empirically integrates CE, BIM, and APM into a single coherent framework tailored specifically for SMEs. The framework is informed by secondary analysis of the BLOOM project dataset (n = 153) and a targeted readiness survey (n = 98) conducted among SMEs in the Mediterranean and Central European regions. The findings reveal a significant gap between awareness and implementation: while over 75% of respondents are familiar with CE and 63% use BIM tools, only 19% demonstrate readiness to integrate all three approaches. The main barriers—training gaps, regulatory ambiguity, and digital immaturity—are explored in detail. This study contributes by introducing a five-pillar framework and by identifying and analysing specific barriers that SMEs face when integrating CE–APM–BIM practices. Nevertheless, strong conceptual alignment exists, with over 80% agreeing on the potential of CE–Agile–BIM synergy. This study offers actionable insights into overcoming adoption barriers and emphasizes the need for policy-driven pilot projects, peer learning, and tailored capacity building to foster regenerative construction practices. Full article

Amid concurrent pressures on water and material resources, recovering valuable ions like lithium and nutrients from brines and wastewater is a critical tenet of the circular economy. This review provides a critical assessment of electro-driven membranes (EDMs) as a key technology platform for achieving this goal with high energy efficiency. A comprehensive synthesis and analysis of the current state-of-the-art of core EDM technologies, including electrodialysis (ED) and membrane capacitive deionization (MCDI), is presented, focusing the analysis on the performance metrics of specific energy consumption and ion selectivity. The findings reveal that the optimal EDM technology is highly application-dependent, with MCDI excelling for dilute streams and ED for concentrated ones. While significant advances in monovalent selective membranes have enabled lithium recovery, achieving high selectivity between ions of the same valence (e.g., Li⁺/Na⁺) remains a fundamental challenge. Moreover, persistent issues of membrane fouling and scaling continue to inflate energy consumption and represent a major bottleneck for industrial-scale deployment. While EDMs are a vital technology for ion resource recovery, unlocking their full potential requires a dual-pronged approach: advancing materials science to design novel, highly selective membranes, while simultaneously developing intelligently integrated systems to surmount existing performance and economic barriers. Full article

Pollution from synthetic polymers, particularly low-density polyethylene (LDPE), poses a significant environmental challenge due to its chemical stability and resistance to degradation. This study investigates an eco-biotechnological approach involving bacterial strains isolated from insect guts—Bacillus cereus LDPE-DB2 (from Achroia grisella) and Pseudomonas aeruginosa LDPE-DB26 (from Coptotermes formosanus)—which demonstrate the ability to degrade LDPE, potentially through the action of lignin-modifying enzymes. These strains exhibited notable biofilm formation, enzymatic activity, and mechanical destabilization of LDPE. LDPE-DB2 exhibited higher LDPE degradation efficiency than LDPE-DB26, achieving a greater weight loss of 19.8% compared with 11.6% after 45 days. LDPE-DB2 also formed denser biofilms (maximum protein content: 68.3 ± 2.3 µg/cm²) compared with LDPE-DB26 (55.2 ± 3.1 µg/cm²), indicating stronger surface adhesion. Additionally, LDPE-DB2 reduced LDPE tensile strength (TS) by 58.3% (from 15.3 MPa to 6.4 ± 0.4 MPa), whereas LDPE-DB26 induced a 43.1% reduction (to 8.7 ± 0.23 MPa). Molecular weight analysis revealed that LDPE-DB2 caused a 14.8% decrease in weight-averaged molecular weight (Mw) and a 59.1% reduction in number-averaged molecular weight (Mn), compared with 5.8% and 32.7%, respectively, for LDPE-DB26. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and gel permeation chromatography (GPC) analyses revealed substantial polymer chain scission and crystallinity disruption. Gas chromatography–mass spectrometry (GC-MS) identified environmentally benign degradation products, including alkanes, alcohols, and carboxylic acids. This study demonstrates a sustainable route to polyethylene biotransformation using insect symbionts and provides insights for scalable, green plastic waste management strategies in line with circular economy goals. Full article

Replacing virgin raw materials with recycled waste in construction products is a key strategy for advancing sustainable development. This study explores the partial substitution of commercial gypsum with powdered waste brick (WB) in gypsum mortars, assessing its impact on mechanical performance, water absorption, and environmental footprint. Mortars were prepared with 0%, 5%, 10%, 20%, and 30% WB by weight. Results indicate that a 20% replacement level enhances flexural strength by 56% and compressive strength by 33% at 28 days, compared to the reference mix. SEM and XRD analyses revealed no formation of new crystalline phases, suggesting that the performance improvement is primarily due to physical interactions and microstructural effects. However, at 30% WB, a significant reduction in adhesion strength was observed, falling below the typical threshold for gypsum-based coatings, which may constrain practical application at higher replacement levels. Environmental assessment showed that both CO₂ emissions and energy consumption decreased by up to 20% with a 30% substitution. A 20% WB content is therefore proposed as the optimal compromise between mechanical performance and environmental benefit. This approach supports circular economy principles by promoting the reuse of ceramic construction waste in the development of new sustainable materials. Full article

Life cycle assessment (LCA) is a standardized tool (ISO 14040) used to evaluate the environmental impacts of products and processes across their entire life cycle, from raw material extraction to end-of-life disposal or recycling. It has become particularly important in the context of engineering materials, where sustainability considerations are critical. Despite challenges such as data quality limitations, variations in system boundary definitions, and methodological inconsistencies, LCA remains an essential tool for assessing and improving product sustainability. This work presents a foundational overview of LCA principles and describes a systematic, step-by-step procedure for its effective application. Additionally, this article revisits the fundamental concepts of carbon footprint (CF) analysis as a complementary tool for quantifying greenhouse gas emissions associated with products and activities. CF analysis underscores the necessity of adopting low-carbon materials and manufacturing processes to minimize embodied energy and reduce environmental emissions. Low-carbon materials are characterized by attributes such as being lightweight, recyclable, renewable, bio-based, locally sourced, and safe for public health. Their development balances the reduction of raw material and resource consumption during production, with increasing product performance, recyclability, and service life, reflecting a cradle-to-cradle, circular economy approach. The integration of LCA and CF methodologies provides an integral framework for assessing environmental performance and supports decision-making processes aligned with global sustainability targets. Full article

The transition to a circular economy (CE) is crucial to sustainable development, necessitating tailored assessment tools to measure circularity at various levels. Recent studies assessing the CE at the municipal level by using statistical data have highlighted the challenge of comparing indicators of differently populated and resourced areas. With existing methodologies, there remains a need for comprehensive approaches that integrate both qualitative and quantitative data to ensure fair and meaningful comparisons. In 2024, Latvia developed and conducted the first CE index at the municipal level. It was based on a self-assessment from municipal governments and citizens, with results calculated into a single index value and four category indices. By applying a mixed methods statistical analysis, this research aimed to compare CE performance, measured by the CE index, and selected socioeconomic and environmental variables between 7 cities and 36 counties or rural municipalities of Latvia. The research concluded that the CE performance is significantly shaped by socioeconomic and spatial factors, with population density and unemployment emerging as consistent predictors. Urban municipalities generally performed better, emphasizing the need for tailored, context-specific CE strategies. Full article

Tensile strength and elastic modulus are key mechanical properties for continuous basalt fibers, which are inherently sustainable materials derived from naturally occurring volcanic rock. This study employs five ensemble learning models, including Extra Tree Regression, Random Forest, Extreme Gradient Boosting, Categorical Gradient Boosting, and Light Gradient Boosting Machine, to predict the tensile strength and elastic modulus of basalt fibers based on chemical composition. Model performance was evaluated using the coefficient of determination (R²), Mean Squared Error (MSE), Root Mean Squared Error (RMSE), and Mean Absolute Error (MAE). Following hyperparameter optimization, the Extreme Gradient Boosting model demonstrated superior performance for tensile strength prediction (R² = 0.9152, MSE = 0.2867, RMSE = 0.5354, and MAE = 0.6091), while CatBoost excelled in elastic modulus prediction (R² = 0.9803, MSE = 0.1209, RMSE = 0.3478, and MAE = 0.2692). SHapley Additive exPlanations (SHAP) analysis identified CaO and SiO₂ as the most significant features, with dependency analysis further revealing optimal ranges of critical variables that enhance mechanical performance. This approach enables rapid data-driven basalt selection, reduces energy-intensive trials, lowers costs, and aligns with sustainability by minimizing resource use and emissions. Integrating machine learning with material science advances eco-friendly fiber production, supporting the circular economy in construction and composites. Full article