Search Results (17,449)

Wood–plastic composites (WPCs) offer a sustainable alternative to solid wood, yet their heterogeneous structure presents challenges in laser machining due to thermal sensitivity and inconsistent material behaviour. This study investigates the optimization of CO₂ laser-cutting parameters for WPCs, focusing on feed rate and assist-gas pressure. Using a 1500 W CO₂ laser, a full factorial experimental design was employed to cut 18 mm thick WPC panels at varying feed rates (1000–3000 mm/min) and gas pressures (1–3 bar). Statistical analyses including MANOVA and linear regression were conducted to evaluate their effects on key machining responses: cutting depth, heat-affected zone (HAZ) width, cut-edge quality, and surface finish. Results indicated that feed rate significantly influences both cutting depth and thermal damage, while gas pressure plays a major role in improving surface quality and reducing HAZ. Optimal combinations were identified for various performance goals, and validation trials at the selected parameters confirmed alignment with predicted outcomes. The optimized settings yielded high-quality cuts with reduced HAZ and enhanced surface characteristics. This study demonstrates the effectiveness of a statistical optimization approach in refining CO₂ laser-cutting conditions for WPCs, offering insights for improved process control and sustainable manufacturing applications. This study also introduces a multi-objective optimization approach that verifies the interaction effects of feed rate and assist-gas pressure, enabling precise and efficient CO₂ laser cutting of 18 mm thick WPCs. Full article

As a renewable and carbon-storing raw material, wood is playing an increasingly important role in the transformation of the construction sector towards a circular economy (CE). However, extant scientific studies have largely analyzed its technical, environmental, and social aspects in isolation from one another. The present article provides a problem-oriented and conceptual narrative overview, integrating these three dimensions from a design perspective. The objective of this study is not to provide a systematic review of the extant literature, but rather to structure existing knowledge by categorizing topics as follows: well-recognized, moderately developed, and niche. This approach enables the identification of gaps and links relevant to architectural practice. A qualitative thematic approach was adopted, underpinned by a comprehensive analysis of peer-reviewed articles sourced from the Scopus and Web of Science databases. This approach was further enriched by the incorporation of a select array of highly cited sources, serving to substantiate the study’s findings and provide a comprehensive overview of the pertinent literature. The review identified four research areas with high potential but low recognition: digital tracking of the life cycle of wooden elements, upcycling of low-quality wood, development of innovative wood-based materials, and socio-cultural acceptance of CE-based architecture. These subjects are currently marginal in the field of research, despite their significant implications for design strategies, adaptive resource use, and the development of interdisciplinary tools. The article posits the necessity of integrating materials science, digital technologies and architectural theory as a prerequisite for the scalable development of circular wood construction. The proposed classification provides a conceptual framework to support further research and guide innovation in the built environment. Full article

Reusing dredged sediments as cement-stabilized fill material offers a sustainable solution for high-fill construction projects, particularly in regions with limited land resources and strict environmental regulations. Nonetheless, the curing pressure from their weight heavily affects these materials’ mechanical properties. This research examines the impact of high curing pressure on the stress–strain behavior, unconfined compressive strength (UCS), and stiffness properties of cement-stabilized dredged sediments containing high moisture levels. Laboratory experiments were conducted under controlled conditions, varying initial water content, cement dosage, and curing pressure. Experimental results demonstrate that initial water content and cement dosage are pivotal in determining the material’s strength, regardless of curing pressure. Curing pressure enhanced peak stress and stiffness while increasing brittleness, resulting in a 41.7% increase in secant modulus for specimens cured under elevated pressure. A novel strength prediction model incorporating a curing pressure correction term was developed to quantify material behavior accurately. Microstructural analysis revealed that curing pressure improved material performance through physical densification and chemical activation, enhancing mechanical properties. This study lays scientific groundwork for the optimal design and application of cement-stabilized dredged sediments in large-scale construction projects, addressing the challenges of high water content and high-fill applications. Full article

This review provides a comprehensive overview of the advancements in magnesium-based cementitious materials (MBCMs), including magnesium oxychloride cementitious material (MOC), magnesium oxysulfate cementitious material (MOS), and magnesium phosphate cementitious material (MPC). The hydration processes and products, performance characteristics, and applications in soil stabilization are systematically discussed. Key findings reveal that MOC exhibits rapid strength development and excellent thermal stability, while MOS demonstrates improved water resistance and mechanical properties. MPC is highlighted for its effectiveness in the immobilization of heavy metals. The environmental impact of MBCMs is also evaluated, highlighting their potential for sustainable development in civil engineering applications. The primary issues and challenges for MBCMs in soil curing include the insufficient stability of hydration products and inadequate understanding of curing mechanisms, leading to variable material properties and difficulties in precisely controlling the curing effects in practical engineering. Additionally, the complex composition of MBCMs and the highly variable characteristics of natural soils result in significant differences in curing effectiveness under different conditions, restricting their application scope and posing risks to project costs and quality stability. Full article

Biomass is one of the most important sources of renewable energy, generating large amounts of ash. This increases the amount of waste, landfill, and air pollution. This work focuses on the sustainable disposal of this ash by producing an innovative binder. The mechanical and microstructural properties of alkali-activated biomass fly ash (BFA) and diatomite (DT) mixtures are currently insufficiently studied. New scientific knowledge of these properties is needed. This study presents the possibility of using BFA and diatomite as aluminosilicate precursors for the production of an alkaline-activated binder. It was found that the reactivity of BFA is relatively low. Based on XRD analysis, the mineral composition of BFA is dominated by quartz and calcite, both of which are non-reactive minerals. Therefore, mixtures with DT were created as precursors. According to Rietveld analysis data, an amorphous part was found in both precursor materials, BFA and DT. Comparing the chemical composition of BFA and DT using XRF and Rietveld analysis data, it was found that the amorphous part of BFA consists of CaO, while the amorphous part of DT consists of SiO₂. Thus, the combination of these precursors should complement each other during the geopolymerisation process. After 28 days of curing, the strength of the binders was dependent on the amount of DT, and the highest strength values, such as 16.4 MPa and 15.3 MPa, were obtained when DT contents were 10% and 30%, respectively. After geopolymerisation, XRD analysis showed that calcium silicate hydrate, hydrotalcite, and calcium aluminium silicate hydrate (zeolite A type) were formed. SEM analysis confirmed the XRD results and showed that DT additives (10% and 30% by weight) improved the microstructure of alkali-activated BFA, which is closely related to compressive strength values. The proposed binder will be useful in the preparation of concrete, which could be used for artificial aggregates or small architectural elements. Full article

The global pursuit of a sustainable and decarbonized energy landscape requires the development of novel materials capable of supporting lightweight construction, advanced energy conversion, storage, and thermal management technologies. Among these, metal foams have emerged as a versatile class of porous materials, offering a unique combination of low density, high surface area, three-dimensional (3D) interconnected porosity, and favorable thermal and electrical conductivities. These attributes make them highly suitable for a broad range of applications critical to the ongoing energy transition, assuming an increasingly central role in enabling clean, efficient, and resilient energy infrastructures. From this key perspective, the present review highlights the relevance of the adoption of metal foams in several fields crucial for the energy transition. By presenting methodologies and outcomes of research results, mainly from the last five years, the paper underscores the potential of low-weight, high-surface, and high-performance porous materials in contemporary and future industry, supporting sustainable development and, more generally, energy transition and circular economy. The approach also aims to minimize negative impacts and promote sustainability, for example, by recycling and transforming waste materials. Full article

Contemporary construction faces the need to reduce its negative impact on the environment, prompting designers, investors, and contractors to seek more sustainable materials and technologies. One area of dynamic development is the use of natural fibers as an alternative to conventional, often synthetic, building components. Plant- and animal-based fibers, such as hemp, flax, jute, straw, bamboo, and sheep’s wool, are characterized by low energy consumption in production, renewability, and biodegradability. Their use is in line with the concept of a circular economy and reduces the carbon footprint of buildings. Natural fibers offer a number of beneficial physical and functional properties, including good thermal and acoustic insulation parameters, as well as hygroscopicity, which allows for the regulation of indoor humidity, improving air quality and comfort of use. In recent years, there has also been a renaissance of traditional building techniques, such as straw construction, often combined with modern engineering standards. Their potential is particularly recognized in green and energy-efficient construction. The article provides an overview of the types of natural fibers available for use in construction and analyzes their technical, environmental, and economic properties. It also draws attention to current regulations, standards, and certifications (e.g., LEED, BREEAM) that promote the popularization of these solutions. In light of the analyzed data, the role of natural fibers as a viable alternative supporting the transformation of the construction sector towards sustainable development is considered. Full article

Additive manufacturing (AM) is an Industry 4.0 technology that assists or replaces the conventional manufacturing (CM) of complex geometries in various sectors, including transport, steel, aerospace, military, and architecture. The aim is to improve processes, reduce energy consumption, atmospheric emissions, and solid waste, and streamline stages while complying with the new environmental regulations. The main objective of this work was to carry out a cradle-to-gate Life Cycle Assessment (LCA), considering the raw material extraction, pre-processing, manufacturing, and post-processing stages, comparing two manufacturing methods for the same ER-90 metal flange part, conventional forging and wire and arc additive manufacturing (WAAM), all following the requirements and operations proposed by the ISO 14040/44 standard. WAAM is a Directed Energy Deposition (DED) technology that uses welding techniques to produce 3D objects with more complex geometries. Compared to the forging industry, which requires a lot of heat and kinetic energy in its metal part production stages, WAAM is a more sustainable and modern alternative because it does not require high temperatures and energy to produce the same parts. The environmental indicators compared in the process stages were energy consumption, greenhouse gas (GHG) emissions, and solid waste. The total energy consumption in AM was 18,846.61 MJ, the GHG emissions were 864.49 kgCO₂-eq, and the solid waste generated was 142.34 kg, which were 63.8 %, 90.5%, and 31.6% lower than the environmental indicators calculated for CM, respectively. Full article

This study investigated the development of biocomposites for use as packaging and film in everyday applications. The utilization of rice flour (RF) as a cheap natural filler in the production of polybutylene succinate (PBS) biocomposites has been shown to reduce environmental issues caused by non-biodegradable plastic waste. The effect of rice flour content on the morphology and properties of PBS and RF biocomposites was comprehensively evaluated. Different amounts of rice flour were considered (0, 10, 20, 30, 40, and 50 phr), and a silane coupling agent and epoxidized natural rubber (ENR-50: 1 phr) were used as interfacial agents to improve compatibility between the matrix (PBS) and filler (RF). The PBS/RF biocomposites were prepared using a two-roll mill and shaped into test specimens and films using a compression molding machine. Batches of the composites containing different amounts of RF were prepared in accordance with the standards, and their morphology and properties, including mechanical properties, density, water absorption, and soil burial degradation, were evaluated. The results revealed that the incorporation of silane-treated RF filler and ENR-50 compatibilizer led to notable improvements in mechanical properties, particularly in tensile modulus, flexural strength, flexural modulus, and hardness. A significant improvement in mechanical performance was observed as the RF content increased, with the highest value recorded at the 50 phr loading. The enhancements observed in the composite properties are due to the inherent rigidity of the RF filler and its improved compatibility with the PBS matrix, which together contribute to a stronger and more efficient material. Additionally, the percentage of water absorption in the PBS/RF biocomposites increased with higher RF content. The results from the soil burial test demonstrated that increasing the RF content positively influenced the biodegradability of the PBS/RF biocomposite materials. Full article

Chitosan is a natural biopolymer with intrinsic antimicrobial properties and strong metal ion chelating properties, making it an ideal matrix for the development of bioactive composites. In this study, silver and copper nanoparticles were synthesized using laser ablation in liquid (LAL) by the ablation of metallic targets into commercial chitosan (Cs) and chitosan produced from Hermetia illucens pupal exuviae (CsE) solutions, avoiding the use of chemical precursors or stabilizing agents. The nanocomposites obtained were characterized by UV–vis spectroscopy, TEM microscopy and FTIR spectroscopy in order to evaluate the size of the nanoparticles and the interactions between the polymer and metal nanoparticles. Antibacterial tests demonstrated the efficacy of Ag-based composites with a minimum inhibitory concentration (MIC) of 0.006 g/L, and Cu-based composites with a MIC of 0.003 g/L against both Escherichia coli and Micrococcus flavus. While the silver composites show antibacterial activity in both colloidal and film forms, the copper composites present antibacterial activity only in colloidal form. Swelling tests indicated that all films maintained a high water absorption capacity, with a swelling index over 200%, unaffected by nanoparticle integration. The results highlight the potential of LAL-synthesized metal–chitosan composites, particularly those based on insect chitosan, as sustainable and effective antimicrobial materials for biomedical and environmental applications. Full article

With the continuous depletion of natural river sand resources and the escalating ecological degradation caused by excessive sand mining, manufactured sand has emerged as a sustainable and environmentally favorable alternative aggregate, playing an increasingly important role in the advancement of green construction materials. Nevertheless, the shrinkage behavior of manufactured sand concrete (MSC) exhibits significant deviations from that of conventional natural sand concrete due to differences in the material characteristics. Existing shrinkage prediction models—such as ACI 209, CEB-FIP 2010, B3, and GL 2000—fail to adequately incorporate the specific properties and substitution effects of manufactured sand, thereby limiting their predictive accuracy and applicability. To bridge this gap, the present study conducted a systematic evaluation of the four aforementioned classical shrinkage prediction models based on experimental data from MSC specimens incorporating varying replacement rates of manufactured sand. The findings revealed that models such as B3 and CEB-FIP 2010 neglected the influence of critical characteristics of manufactured sand—namely, particle morphology, gradation, and stone powder content—on the cementitious matrix and interfacial transition zone, which led to substantial prediction discrepancies. Accordingly, a nonlinear regression-based correction function was developed, introducing the manufactured sand content as a key influencing variable to recalibrate and enhance the ACI 209 and GL 2000 models for a more accurate application to MSC. The modified models exhibited markedly improved fitting performance and predictive robustness across the full range of manufactured sand replacement ratios (0–100%), thereby offering a more reliable framework for modeling the shrinkage development of MSC. Full article

The advancement of catalytic materials is critical to improving the performance, reducing the cost and enhancing the sustainability of Proton Exchange Membrane (PEM) fuel cells and electrolyzers. Although Platinum Group Metal (PGM)-based electrocatalysts exhibit high electrochemical activity, their limited availability and the environmentally intensive extraction pose significant challenges. This study aims to demonstrate the direct reuse of recycled impure platinum (Pt) precursors for the synthesis of effective Pt/C electrocatalysts as a viable step toward circular hydrogen economy implementation. A low-cost and eco-friendly chlorine-based hydrometallurgical method was successfully employed to recycle over 99% of Pt from End-of-Life (EoL) Membrane Electrode Assemblies (MEAs), with an industrial perspective. Recycled metal precursor was used without purification to synthesize Pt/C electrocatalyst via a scalable and sustainable method. The catalyst was structurally and chemically characterized, and their electrochemical performance towards the Oxygen Reduction Reaction (ORR) was conducted under conditions simulating real operating environments. The recycled-metal-derived catalyst demonstrated comparable activity toward ORR (170 A/gPt) relative to a commercial catalyst, indicating its potential as viable alternative to conventional PGM-based catalysts. By integrating energy-efficient recycling with advanced material design, this work supports the development of cost-effective and green solutions for clean energy technologies aligned with a circular hydrogen economy model. Full article

In recent years, the application of sustainable cementitious materials has become of great importance to improve buildings efficiency and to achieve carbon neutrality. Main goal of this work to study and develop BIOAERMAC, an innovative construction material with low density, composed of synthetic anhydrous calcium sulfate obtained as by-product in the industrial production of hydrofluoric acid and an aerating agent composed of microorganisms and peroxides, with the addition of rubber from end-of-life tires (ELTs). A density from 600 to 950 kg/m³ with a compressive strength up to 6.0 MPa and a thermal conductivity from 0.15 to 0.3 W/mK are the key performance metrics of BIOAERMAC composites. Experimental results showed an improvement in technical and energy performance, combined with a reduction in natural resource consumption and the wide quantity of by-product reintroduced into the production process. Full article

In this study, a bio-nanocomposite integrating calcium caseinate, modified starch, and bentonite nanoclay was formulated and synthesized into film form via solution casting. Glycerol was incorporated for plasticization, and polyvinyl alcohol (PVA) was used to enhance the structural and chemical attributes of the material. The addition of PVA and bentonite notably improved the mechanical strength of the casein-based matrix, showing up to a 30% increase in tensile strength compared to similar biopolymer formulations. Water vapor permeability was significantly reduced when compared to previously reported casein–starch formulations, evidencing the barrier-positive effects of bentonite nanostructures. The microbial analysis confirmed that the quantity of bacterial colonies remained within permissible levels for non-antimicrobial biodegradable films; however, further antibacterial evaluations are advised. Biodegradability testing showed a consistent degradation trend, with full disintegration extrapolated to occur around 13 weeks under natural soil conditions. This study offers exploratory insight into the development of functional and biodegradable films using biopolymer blends and nanoclay suspensions, highlighting their potential in sustainable food packaging applications. Full article

The lack of cultural spaces and the inadequate preservation of architectural heritage hinder the development of ecotourism in Ollantaytambo. This research aims to propose an architectural design for green infrastructure that supports the growth of ecotourism at the Ollantaytambo archeological site, located in the Urubamba Province, Peru. The study consists of three main phases: a literature review; a site analysis focusing on climate, flora, and fauna; and the development of a comprehensive architectural proposal. The process is supported by digital tools, including Google Earth Pro 2024, OpenStreetMap 2024, SketchUp 2024, Lumion 2024, Photoshop 2024, and 3D Sun-Path 2024. The resulting design includes the implementation of a sustainable cultural center, conceived to ensure seasonal thermal comfort through the use of green roofs and walls, efficient irrigation systems, and native vegetation. The proposal incorporates elements of Cusco’s vernacular architecture by combining traditional earth-based construction techniques, such as rammed earth, adobe, and quincha, with contemporary materials, such as bamboo and timber, in order to improve the energy and environmental performance of the built environment. Furthermore, the project integrates a rainwater-harvesting system and a photovoltaic lighting system. It includes 30 solar-powered luminaires with an estimated monthly output of 72 kWh, and 135 photovoltaic panels capable of generating approximately 2673 kWh per month. In conclusion, the proposed design blends naturally with the local environment and culture. It adheres to principles of sustainability and energy efficiency and aligns with Sustainable Development Goals (SDGs) 3, 6, 7, 11, and 15 by promoting heritage conservation, environmental regeneration, and responsible ecotourism. Full article