Search Results (2,255)

Wire electrochemical discharge machining (WECDM) integrates the effectiveness of electrical discharge machining (EDM) with the superior quality of electrochemical machining (ECM), leading to enhanced machining efficiency, excellent surface finish, and significant potential for advancement. However, previous research has mainly focused on the processing of non-metallic materials, with little research in the field of the microfabrication of thick metal materials. The wire electrochemical discharge machining process with large aspect ratios is more complex. Accordingly, a unidirectional traveling wire electrochemical discharge micromachining (UWECDMM) method using a glycol-based electrolyte was proposed. The method employs a glycol solution with low conductivity and a neutral salt, facilitating enhanced mass transfer efficiency through a unidirectional traveling wire, and enabling the realization of high-efficiency, high-precision, and recast-free processing. The phenomenon of discharge in UWECDMM was observed in real-time with a high-speed camera, while the voltage and current waveforms throughout the machining process were carefully analyzed. It was found that electrolysis and discharge alternate. Experiments were conducted to investigate the wire traveling pattern, the recast layer, and the wear of the wire electrode. It was found that due to the small energy of a single discharge, the wear of wire electrodes is minimal after multiple uses and can be reused. Under optimal parameters, a machined surface without a recast layer can be obtained. In the final stages, a standard structure was machined on plates of 10 mm thickness made of pure nickel and 304 stainless steel, using a tungsten wire measuring 30 μm in diameter. The feed rate achieved was 1 μm/s, the surface roughness (Ra) measured 0.06 μm, and the absence of a recast layer confirmed the method’s sustainability and quality traits, indicating significant potential in microfabrication. Full article

This study used widely available waste biomass, corn cob (CC), to remove Pb ions from aqueous solutions. A two-step conversion of this material was carried out to improve its adsorption characteristics. Firstly, CC was prepared by hydrothermal carbonization; afterward, the obtained hydrochar was doped by MgCl₂ and pyrolyzed. The synthesized hydro-pyrochar (HCC-Mg) was used for adsorption experiments in a batch system. The surface and structural properties of HCC-Mg were characterized by SEM-EDX and FTIR analysis before and after Pb adsorption. Kinetic and isotherm models were applied to the experimental results. It was confirmed that Pb adsorption on HCC-Mg occurred rapidly, with a maximum adsorption capacity of 87.08 mg/g. The pseudo-second-order model best described the adsorption process, while the best fit of the experimental data was observed with the Sips isotherm model. The results of this study showed that the capacity of the synthesized HCC-Mg material had increased more than 14 times compared with raw CC. In addition, the synthesized material had the potential to be reused for at least five cycles with minimal loss of adsorption capacity and efficiency. Moreover, the results confirmed that HCC-Mg can be used as an efficient, sustainable adsorbent of Pb from polluted water. Full article

Ecological restoration and brownfield reuse are important issues in the current field of urban sustainable development and environmental protection. This paper adopts bibliometric and network analysis methods, using more than 600 literature from Web of Science (WOS) and China National Knowledge Infrastructure (CNKI) databases as research objects, to analyze the research trends, main researchers, contributions of different disciplines, and research hotspots in ecological restoration and brownfield reuse. Based on the results of quantitative analysis, this paper reviews the main research theories, methods, and technologies of ecological restoration and brownfield reuse at home and abroad, as well as response strategies in different regions and future prospects under challenges. Among the top 10 disciplines in terms of disciplinary contribution, the discipline with the highest relevance in the research articles of CNKI is “Environmental Science and Technology”, accounting for approximately 47.24%. The discipline with the highest relevance in the research articles of WOS is “Building Science and Engineering”, accounting for approximately 61.21%. In terms of research theories and methods, emphasis is placed on the application of ecological engineering, landscape ecology, land economics, and sustainable development methods. At the same time, adaptive management methods are emphasized, aiming to achieve a balance between ecological protection and urban development. In terms of response strategies for different regions, the main strategies for ecological restoration and brownfield reuse are proposed from five main aspects: reducing soil erosion and controlling water pollution, restoring ecological communities and enhancing biodiversity, landscape reshaping and spatial transformation, tourism development, and leisure space design. Based on the current challenges in technology, law, funding, management, and society, research prospects for strengthening interdisciplinary integration, digital drive, interdisciplinary collaboration, and multi-party cooperation in the future are proposed. It can be seen that research in this field is no longer just a simple ecological issue, but a comprehensive social problem. Full article

During the last decades, the ever-growing evolution of the construction industry has led to a significant increase in demand for increasingly high-performing construction materials both in terms of mechanical characteristics and sustainability. Focusing on concrete, several researchers have designed different mixes to improve mechanical properties such as compressive strength, workability and durability, and in many of the proposed mixes, the use of industrial waste stands out both for their ability to improve the mechanical properties of concrete and for the importance of their reuse from a sustainability point of view. In this paper, the use of two waste materials, perlite and rhyolite, in concrete mix design was studied in detail, considering their influence on the compressive strength at 7 and 28 days of curing. The waste materials were introduced in the mix design as substitutes for cement in percentages of 15% and 30% in weight. In addition, perlite was micronized to two different particle sizes, 20 μm and 63 μm, respectively, according to what is already used in concrete within perlite in the mix design. The behavior of the structural concrete containing perlite and rhyolite was compared in terms of compressive strength, Young modulus and produced equivalent CO₂ with that of a standard C25/30 reference concrete, and with that of a mix design created using other waste materials, namely fly ash, metakaolin and silica fume, considering cement replacements that are always at 15% and 30% by weight. Moreover, ultrasonic testing and rebound hammer tests were run to evaluate a possible relationship between the physical-mechanical properties of the design mixes and their volumetric and surface characteristics. Full article

The adaptive reuse of urban structures is gaining significant attention due to its multiple benefits for sustainable urban development. Current research on repurposing initiatives provides valuable insights that can guide these practices from a research-based perspective. This paper aims to systematically review the existing literature on the adaptive reuse of buildings to develop a framework that outlines studies and findings on how repurposing practices contribute to specific sustainable development goals and their targets. The systematic literature review focuses on research published from 2018 to the end of 2024, serving as the foundation for this framework. The findings indicate that repurposing projects can make direct contributions to nine sustainable development goals. The strongest impacts were identified in relation to goals 4, 11, and 17. For goal 4, repurposing projects serve as valuable case studies, demonstrating how existing architecture can function as an asset that benefits urban sustainability. Concerning goal 11, the literature emphasises the importance of inclusivity in decision making throughout various stages of adaptive reuse and highlights the protection of unique architectural features as a strategy to enhance social capital and provide cultural and economic improvements. Adaptive reuse supports goal 17 by fostering public–private partnerships and encouraging transparent policy communication, which aids the development of new policies focused on sustainability. The results can assist urban planners, architects, and developers in making research-based decisions regarding underutilised buildings in urban contexts. Full article

Unfired bricks offer a sustainable alternative to traditional fired bricks by enabling the large-scale reuse of industrial, construction, and municipal wastes while significantly reducing energy consumption and greenhouse gas emissions. This review contributes to eliminating knowledge fragmentation by systematically organising stabiliser technologies, performance metrics, and sustainability indicators across a wide variety of unfired brick systems. It thus provides a coherent reference framework to support further development and industrial translation. Emphasis is placed on the role of stabilisers—including cement, lime, geopolymers, and microbial or bio-based stabilisers—in improving mechanical strength, moisture resistance, and durability. Performance data are analysed in relation to compressive strength, water absorption, drying shrinkage, thermal conductivity, and resistance to freeze–thaw and wet–dry cycles. The findings indicate that properly stabilised unfired bricks can achieve compressive strengths above 20 MPa and water absorption rates below 10%, with notable improvements in insulation and acoustic properties. Additionally, life-cycle comparisons reveal up to 90% reductions in CO₂ emissions and energy use relative to fired clay bricks. Despite technical and environmental advantages, broader adoption remains limited due to standardisation gaps and market unfamiliarity. The paper concludes by highlighting the importance of hybrid stabiliser systems, targeted certification frameworks, and waste valorisation policies to support the transition toward low-carbon, resource-efficient construction practices. Full article

Segmented timber shells present a novel building system that utilizes modular, planar building components to create lightweight free-form structures in architecture. Recent advancements in the research field of segmented timber shells pursue, among others, two fundamentally opposing research objectives. 1. The modularity of their building components facilitates the reuse of such structures in response to a changing built environment. 2. Advanced developments aim at establishing segmented timber shells as permanent building structures for sustainable architecture. This paper addresses the first research objective through the successful relocation of the BUGA Wood Pavilion in the context of the proposed methodology of Co-Design for circular construction. The methods and results involve integrative design and engineering processes and advanced quality assessment methods, including structural, geodetic, and physical properties for modular timber constructions. The BUGA Wood Pavilion serves as a building demonstrator for the presented research on segmented shells as lightweight, reusable, and durable timber structures. Full article

Background: Food waste is a significant global issue with environmental, social, and economic consequences. In 2022, approximately 1.05 billion tons of food were wasted worldwide, with 220 million tons lost during the production and processing stages. Strategies to reduce food waste include full food utilization and the reuse of clean leftovers, which promote food security, efficient resource use, and the valorization of nutrients found in food. Objective: The aim of this study was to map existing scientific literature on nutritional intervention programs that incorporate full food utilization and the reuse of clean leftovers as tools for promoting sustainability and reducing food waste. The review seeks to consolidate existing knowledge, support public policy development, and encourage the adoption of sustainable food practices. Methods: A scoping review was conducted based on the Joanna Briggs Institute (JBI) manual and following the PRISMA-ScR checklist. The search was conducted in four scientific databases (PubMed, Embase, Cochrane Library, and Virtual Health Library) and included articles published between 2014 and 2025. Intervention studies promoting full utilization of plant-based foods and the reuse of clean leftovers were included. Results: After analyzing 2268 studies, 14 relevant studies were selected, with interventions including culinary workshops and educational programs on using parts of food typically discarded, such as peels and seeds. These programs were successful in reducing waste and promoting more sustainable and nutritious diets. Conclusions: Nutritional intervention programs that promote full food utilization and clean leftover reuse are effective in reducing waste and fostering sustainable diets. To maximize their impact, these practices should be integrated into public policies and scaled in institutional settings such as schools, hospitals, and community kitchens. Full article

The conventional linear economic model has intensified global resource depletion and environmental degradation, underscoring the pressing necessity for a transformation toward the Circular Economy (CE). Currently, research generally segregates materials, products and services within the CE, overlooking their hierarchy and interactions in circular performance. Employing a mixed methodology of induction and deduction, this study constructs a triple-level proposal for the CE from a design perspective. The proposal integrates material recycling, product reuse and service circulation into a multi-hierarchical progression, clarifying the priorities of the CE and sustainable design. It not only enriches the theoretical basis of the CE and sustainable design, but also offers a transformative perspective for optimizing circular performance. Case studies in the deductive stage provide measurable criteria to assess the performance of each level, while a design workshop featuring the CE canvas and heuristics is adopted to test the effectiveness of our proposal in guiding practice. The results demonstrate the theoretical and practical feasibility of the proposal. This study emphasizes the progression from materials to products and services, exploring the potential of the triple-level proposal in guiding design and improving circular performance. By proposing policy recommendations based on the proposal, this study provides stakeholders with an actionable roadmap for CE implementation. Full article

Augmented Reality (AR) seamlessly blends the real-world environment with digitally generated content, creating an interactive hybrid experience where both realities coexist. This paper explores an augmented reality application developed for natural heritage education, specifically designed to enhance indoor learning. The focus is on a learning activity titled Exploring the Aquarium, implemented by the Education Centre for the Environment and Sustainability (E.S.E.C.) of Kastoria as part of an environmental education program. The activity enriches students’ knowledge and experiences during their aquarium visit, fosters active participation in the learning process, stimulates cognitive interest, and encourages actions that support the ecological restoration of aquatic ecosystems. This paper presents the application’s design criteria, thematic focus, learning objectives, and core functionalities. Additionally, the paper presents findings from quantitative research evaluating the learning experience. A questionnaire tailored for AR applications was employed to assess aspects such as challenge, educational value (knowledge gained), user collaboration, and intention to reuse the app. Data were collected from 148 K-12 students during the 2023–2024 school year. Descriptive statistical analysis revealed that all factors were evaluated highly. The results indicate that the AR-enhanced educational activity captured the students’ interest and facilitated a collaborative learning environment. The application was positively rated for its functionality, usability, informational content, and the satisfaction it provided, as well as its ability to encourage cooperation and future reuse. Full article

This study aims to address the challenge of backfill compaction in the confined spaces of municipal utility tunnel trenches and to develop an environmentally friendly, zero-cement-based backfill material. The research focuses on the excavation slag soil from a utility tunnel project in Handan. An alkali-activated industrial-solid-waste-excavated slag-soil-based controllable low-strength material (CLSM) was developed, using NaOH as the activator, a slag–fly ash composite system as the binder, and steel slag-excavated slag as the fine aggregate. The effects of the water-to-solid ratio (0.40–0.45) and the binder-to-sand ratio (0.20–0.40) on CLSM fluidity were studied to determine optimal values for these parameters. Additionally, the influence of excavated soil content (45–65%), slag content (30–70%), and NaOH content (1–5%) on fluidity (flowability and bleeding rate) and mechanical properties (3-day, 7-day, and 28-day unconfined compressive strength (UCS)) was investigated. The results showed that when the water-to-solid ratio is 0.445 and the binder-to-sand ratio is 0.30, the material meets both experimental and practical requirements. CLSM fluidity was mainly influenced by the excavated soil and slag contents, while NaOH content had minimal effect. The unconfined compressive strength at different curing ages was negatively correlated with the excavated soil content, while it was positively correlated with slag and NaOH content. Based on these findings, the preparation of “zero-cement” CLSM using industrial solid waste and excavation slag is feasible. For trench backfill projects, a mix of 50–60% excavated soil, 40–60% slag, and 3–5% NaOH is recommended for optimal engineering performance. CLSM is a new type of green backfill material that uses excavated soil and industrial solid waste to prepare alkali-activated materials. It can effectively increase the amount of excavated soil and alleviate energy consumption. This is conducive to the reuse of resources, environmental protection, and sustainable development. Full article

Concrete and mortar production consumes significant natural resources, leading to environmental concerns and sustainability challenges. Sustainable alternatives, such as industrial byproducts, have been explored to replace clinkers and aggregates. Basalt rock powder (BRP) is a promising option due to its physical and chemical properties, including its better particle size distribution and compatibility with cementitious composites, and studies have highlighted its pozzolanic activity and its potential to improve mechanical properties (compressive strength, flexural strength, and durability). Reusing rock dust as a raw material could transform it into a mineral byproduct, benefiting the new material and reducing waste volumes. This article presents a systematic literature review on the use of BRP in construction materials, conducted using the Scopus, ScienceDirect, PubMed, and Web of Science databases and following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) procedures. The search resulted in 787 articles (up to December 2024) and, after the screening process, 17 met the inclusion criteria. From the selected articles, information regarding the utilization of this waste product; its influence on mechanical properties, pozzolanic activity, and durability; and the sustainability associated with its use was compiled. The risk of bias was low as the search was comprehensive, all the papers were peer-reviewed, and all authors reviewed the papers independently. In conclusion, the studies demonstrate the potential of using BRP as a component of cementitious materials, indicating it as a possible innovative solution to the current challenges in the construction industry. Full article

This paper presents an analysis of energy use and sector coupling in a local energy community using a model based on energy cost centres (ECCs), functional units for decentralised responsibility and optimisation of energy use within defined system boundaries. The ECC model enables structured identification and optimisation of energy and material flows in complex industrial and urban settings. It was applied to a case study involving an energy-intensive steel plant and its integration with the surrounding community. The study assessed the potential for renewable electricity production (7914 MWh annually), green hydrogen generation, battery storage, and the reuse of 11,440 MWh of excess heat. These measures could offset 9598 MWh of grid electricity through local production and savings, reduce natural gas use by 4,116,850 Nm³, and lower CO₂ emissions by 10,984 tonnes per year. The model supports strategic planning by linking sectoral actions to measurable sustainability indicators. It is adaptable to data availability and stakeholder engagement, allowing both high-level overviews and detailed analysis of selected ECCs. Limitations include heterogeneous data sources, uneven stakeholder participation, and the need for refinement of sub-models. Nonetheless, the approach offers a replicable framework for integrated energy planning and supports the transition to sustainable, decentralised energy systems. Full article

The use of agro-industrial waste, such as wood ash or biomass ash, has been adopted as an alternative to synthetic fertilizers for providing nutrients to plants. This study aimed to evaluate the levels of primary and secondary macronutrients in soil cultivated with chrysanthemum under different types of fertilization management: organic, organomineral, and mineral, with and without liming. The experiment was conducted in a greenhouse for 185 days, using a randomized blocks design in a 5 × 2 factorial scheme: five fertilization types (incubated and unincubated wood ash, organomineral fertilizer, mineral fertilizer, and control) and two levels of liming (without liming and 70% base saturation) with five replicates. The soil used was Oxisol. The phosphorus, potassium, calcium, magnesium, and sulfur contents in the soil after cultivation were analyzed. There was a 77% increase in potassium in treatments with ash compared to treatments without ash. The corrected soil presented 173.2 mg dm⁻³ of potassium, compared to 153.6 mg dm⁻³ in the uncorrected soil, an increase of 11.6%. The calcium levels increased by 60% with the application of ash (incubated or not) and organomineral fertilizer, compared to soils without ash. Liming increased calcium by 1.12 cmol_c dm⁻³. Fertilizers with ash associated with liming resulted in higher magnesium levels. The sulfur content varied according to the fertilizer, with non-incubated ash showing the highest value (69.11 mg dm⁻³) compared to the control (11.08 mg dm⁻³), a difference of 83.96%. Organomineral fertilizer is an alternative for increasing the availability of macronutrients in the soil, allowing a second cropping cycle without the need to manage soil fertility, contributing to sustainable agriculture, encouraging the reuse of waste, and reducing the use of mineral fertilizers. Full article

The architectural legacy of the French colonial period forms a key part of Vietnam’s urban identity, especially in Hue. Yet, this heritage is rapidly declining: from over 240 structures in 2000, fewer than 100 remain today. This study introduces a heritage-based evaluation framework to assess and preserve French colonial buildings using Le Loi Street, Hue’s historic “Western quarter” as a pilot site. Fourteen colonial-era buildings were systematically assessed through field surveys and expert consultation. A total of 40 specialists participated in the criteria development process, and eight selected experts conducted detailed building evaluations. The final framework includes three main categories and nine specific criteria, based on a 100-point scale, incorporating architectural integrity, historical and cultural significance, contextual fit, and adaptive reuse potential. The results show that all the surveyed buildings qualify as Group A or B, warranting strict conservation or minimal renovation. The study emphasizes the value of localized, expert-informed approaches to heritage planning. The research provides a practical foundation for integrating historic architecture into context-sensitive urban conservation strategies in Hue and comparable Southeast Asian contexts. Full article